On 9 May 2023, Lockheed Martin announced that its hybrid airship business, including intellectual property and related assets, had been transitioned to a newly formed, commercial company called AT2 Aerospace. The Lockheed Martin press release reported, “AT2 Aerospace, based in Santa Clarita, California, is extending our work to bring hybrid airships to fruition. The AT2 team is developing airship solutions to support commercial and humanitarian applications around the world. Dr. Robert Boyd, retired Lockheed Martin Hybrid Airship program manager, is president and chief operating officer of AT2 Aerospace.”
2. Background on Lockheed Martin’s hybrid airship program
Since the 1980s, Lockheed Martin has been developing several different design approaches for semi-buoyant, hybrid airships with lifting body hulls. That work became focused in Lockheed Martin’s Advanced Development Programs (the Skunk Works) in Palmdale, CA, and produced an extensive series of patents related to large, hybrid airship design.
The only Lockheed Martin hybrid airship to fly was the P-791, which was a 120 foot (36.6 meter) long, tri-lobe, semi-buoyant hybrid airship that flew under a Defense Advanced Research Projects Agency (DARPA) sponsored Project WALRUS Phase 1 contract, and also served as a sub-scale technology demonstrator for future Lockheed Martin heavy-lift hybrid airships. The first flight of the P-791 took place on 31 January 2006 at Lockheed Martin’s facility in Palmdale. Airship magazine reported that the P-791 flew six times. Lockheed Martin claimed that all flight test objectives were successfully met and there were no subsequent flight tests.
Lockheed Martin P-791. Source: Lockheed Martin (2006)
In March 2011, Lockheed Martin announced that it planned to develop a larger commercial version of the P-791, to be called SkyTug, which would be a scaled up hybrid airship designed to carry at least 20 tons of cargo. A trademark application for the term “SkyTug” was filed on 25 August 2011.
By 2013, reference to SkyTug had disappeared and Lockheed Martin was promoting the LMH-1 as their next large commercial hybrid airship based on the P-791 design.
General arrangement of the LMH-1 hybrid airship. Source: Lockheed Martin
Rendering, LMH-1 bow quarter view.Source: Lockheed Martin via BBC (November 2019)
On March 12, 2012 the U.S. Federal Aviation Administration (FAA) announced that Lockheed Martin Aeronautics submitted an application for type certification for the model LMZ1M (LMH-1), which is “a manned cargo lifting hybrid airship incorporating a number of advanced features.” The FAA assigned docket number FAA-2013-0550 to that application.
To address the gap in airship regulations head-on, Lockheed Martin submitted to the FAA their recommended criteria document, “Hybrid Certification Criteria (HCC) for Transport Category Hybrid Airships,” which is a 206 page document developed specifically for the LMZ1M (LMH-1). The HCC is also known as Lockheed Martin Aeronautics Company Document Number 1008D0122, Rev. C, dated 31 January 2013. You can download the HCC document and related public docketed items from the FAA website here:
In November 2015, the FAA’s Seattle Aircraft Certification Office approved Lockheed’s project-specific certification plan for the LMZ1M (LMH-1). In a 17 November 2015 press release, Lockheed Martin announced:
“Given that Hybrid Airships did not fit within existing FAA regulations, the team worked to create a new set of criteria allowing non rigid hybrid airships to safely operate in a commercial capacity. Transport Canada was also involved in the development of this criteria to ensure it included safety concerns unique to Canada.”
“Lockheed Martin and the FAA have been working together for more than a decade to define the criteria to certify Hybrid Airships for the Transport Category. This criteria was approved by the FAA in April 2013. Following that approval, the team has been developing the project specific certification plan over the past two years, which details how it will accomplish everything outlined in the Hybrid Certification Criteria.”
“Earlier this year Lockheed Martin along with Hybrid Enterprises LLC kicked off sales for the 20 ton variety of the Hybrid Airship. They are on track to deliver operational airships as early as 2018.”
No new documentation was subsequently added to the public webpage for docket FAA-2013-0550, so there was no public visibility of the type certification effort.
In September 2017, Lockheed Martin reported it had Letters of Intent (LOIs) for 24 LMH-1 hybrid airships, with their largest customer being Straightline Aviation (https://www.straightlineaviation.com), which had signed an LOI for 12 LMH-1s. At that time, the first “float out” of the LMZ1M (LMH-1) had slipped to 2019. As of May 2023, the airship has not yet been “floated out”.
On 9 May 2023, Lockheed Martin reported, “For some time, we have been in search of a transition partner to continue development of this important commercial work.” That “transition partner” is the newly formed, commercial company AT2 Aerospace.
3. The AT2 Aerospace Z1 Hybrid Airship
As portrayed on the AT2 Aerospace website, their Z1 hybrid airship appears to be the current incarnation of the former Lockheed Martin LMH-1. AT2 Aerospace summarizes the main attributes of their Z1 hybrid airship as follows:
“AT2 Aerospace’s revolutionary hybrid airship is the future of aviation technology. Capable of operating in the most remote and inaccessible locations, this innovative aircraft offers a cost-effective solution for heavy cargo transpiration while minimizing environmental and social impact.”
“The Z1’s unique Air Cushion Landing System (ACLS) allows the Z1 to land and takeoff from almost any location on the planet.
The Z1 utilizes buoyant lift technology delivering exceptional fuel efficiency, minimizing carbon emissions, and ultimately reducing transportation costs.
The Z1 will connect emerging economies to global trade networks.
The Z1 moves cargo faster than sea and land transportation at a fraction of the cost of existing cargo aircraft, filling a major gap in the global transportation market from a speed vs. cost perspective.”
AT2 Aerospace also identified the following attributes:
Simple controls minimize human error
Large volume cargo bays, larger payloads
Safer in icing effects
Quiet: Ideal for noise sensitive locations
AT2 Aerospace expects that their Z1 hybrid airship will “open the entire world to commerce, humanitarian aid and exploration with affordable and reliable operations.”
General arrangement of the Z1 hybrid airship. Source: AT2 Aerospace
The near-term challenge for AT2 Aerospace will be to get clarity from the FAA on the actions remaining, and the approximate time scale, to conclude the first-ever type certification process for a hybrid airship in the U.S. With a type certificate in hand, the Z1 can be put to the test by a few early-adopters in what hopefully will become an emerging worldwide commercial airship market.
That’s the title of my favorite Moody Blues album. It’s also the current status of commercial civilian access to space.
The leading contenders are Richard Branson, with his firm Virgin Galactic Holdings, Inc., and Jeff Bezos, with his firm Blue Origin. 2021 is the year both firms plan to make their first commercial civilian sub-orbital flights with paying customers.
On 25 June 2021, the Federal Aviation Administration (FAA) granted approval of Virgin Galactic’s full commercial space-launch license. The FAA also is reviewing Blue Origin’s commercial space-launch license application, and final approval is expected soon. For commercial spaceflight, the FAA’s primary regulatory role is to ensure that the spaceflight activity is not a hazard to the general public or other aviation activities. The FAA does not regulate the design and operating characteristics of the spacecraft, as it does for commercial aircraft. Passengers flying on commercial spacecraft must acknowledge the risk by signing a waiver….and people are lining up and will be paying hefty sums to become civilian astronauts.
Virgin Galactic
Virgin Galactic successfully completed its third manned test flight of the Spaceship II on 22 May 2021, with VSS Unity flying for the first time from New Mexico’s Spaceport America, which is located in the high desert near the small town of Truth-or-Consequences. I visited Spaceport America in 2015 when it was a complete but very quiet place, with only a Spaceship II mockup. That has all changed in 2021 as Virgin Galactic completed its testing program and is now preparing for its first commercial flights.
Spaceship II flight profile. Source: Virgin GalacticVirgin Galactic’s Spaceship II being carried aloft by the White Knight Two mothership. Source: Virgin GalacticSpaceship II, VSS Unity, being dropped from the White Knight Two to start its third manned test flight on 22 May 2021. Source: Virgin Galactic
Virgin Galactic will be flying its two Spaceship II vehicles, VSS Unity and VSS Enterprise, from its base at Spaceport America. Virgin announced that the next sub-orbital flight is scheduled to occur on 11 July 2021 and Richard Branson is expected to be among the six people on board, all Virgin employees.
Virgin Galactic’s long-range plan is to operate 400 flights per year, per spaceport. To achieve this goal, Virgin recently completed the first of its next generation Spaceship III vehicles, VSS Imagine, and has started manufacturing the next Spaceship III, VSS Inspire.
Introducing Spaceship III, VSS Imagine. Source, both photos: Virgin Galactic
You can read the latest news on Virgin Galactic’s commercial space program at the following link: http://www.virgingalactic.com/
Blue Origin’s New Shepard spacecraft is named for US astronaut Alan Shepard, who made the first US sub-orbital flight on 5 May 1961 on the Mercury-Redstone 3 mission and became the second man in space (after Russian astronaut Yuri Gagarin). To date, Blue Origin has made 15 consecutive unmanned launches with successful crew capsule landings, plus a successful pad escape test in 2012.
Contingent on receiving FAA license approval, Blue Origin announced that it has scheduled its first manned flight on 20 July 2021 from its west Texas launch facility near the town of Van Horn. This is the 52nd anniversary of the Apollo 11 moon landing. The four passengers for the first New Shepard manned sub-orbital flight will be Jeff Bezos, his brother Mark, Wally Funk (who is the last surviving member of NASA’s 13 female astronaut candidates for Project Mercury in the 1960s), and a fourth (as yet unnamed) passenger who won an auction by bidding $28 million for the last passenger seat. That amount will be donated to Blue Origin’s foundation, Club for the Future, to inspire future generations to pursue careers in STEM and help invent the future of life in space.
New Shepard flight profile. Source: Blue OriginA New Shepard launch. Source: Blue OriginA New Shepard launch vehicle makes an autonomous landing. Source: Blue OriginThe crew capsule is recovered separately. Source: Blue Origin
Blue Origin advertises, “This Seat Will Change How You See the World.” I have no doubt that it will. Find out more by visiting the Blue Origin website at the following link: http://www.blueorigin.com
Update 3 Sep 2021: The threshold has been crossed
Congratulations to Virgin Galactic and Blue Origin for their first successful suborbital passenger flights.
On 11 July 2021, the Virgin Galactic flight named Unity 22 took off from Spaceport America with pilots Dave Mackay and Mike Masucci and four passengers: Richard Branson, Beth Moses (Virgin Galactic’s chief astronaut instructor), Sirisha Bandla (VP of government affairs), and Colin Bennett (lead operations engineer). The flight reached a peak altitude of 282,000 feet (53.5 miles / 86.1 kilometers) and flew back for a landing on the runway at Spaceport America.
Virgin Galactic says that it already has more than 600 reservations at a “ticket” price of $250,000 apiece. Expensive? Yes, but such a trip was impossible to do even a year ago. Regular passenger flights are expected to start in 2022. What will the price for this type of trip into space be in a decade? Probably still pretty expensive, but this is just a first step in democratizing space.
L-R: David (Mac) Mackay, Colin Bennett, Beth Moses, Richard Branson, Sirisha Bandla & Mike (Sooch) Masucci. Source: Virgin Galactic
On 20 July 2021, the FAA Office of Commercial Space Transportation issued an order revising their criteria for its FAA Commercial Space Astronaut Wings Program. SpaceNews reported: “According to the order, the FAA will award wings to commercial launch crew members who meet the requirements in federal regulations for crew qualifications and training, and fly on an FAA-licensed or permitted launch to an altitude of at least 50 miles (80 kilometers). The order also requires those crew members to have demonstrated ‘activities during flight that were essential to public safety, or contributed to human space flight safety.’ The last provision is new in the order.”
Commercial Space Astronaut Wings previously were awarded to Dave Mackay, Mike Masucci and Beth Moses for their roles as crew during flight testing of Spaceship II. The first commercial astronaut wings were awarded in 2004 to Virgin Galactic pilots for Spaceship I, Mike Melvill and Brian Binnie.
The FAA approved Blue Origin’s flight on 12 July, one week before the 20 July 2021 launch date. The autonomous New Shepard vehicle does not have a pilot or crew. The 20 July flight carried four passengers: company founder Jeff Bezos, his brother Mark, former astronaut candidate Wally Funk and Oliver Daemen. The flight reached a maximum altitude of 351,000 ft (66.5 miles / 107 kilometers), above the Kármán Line at 62 miles / 100 kilometers above mean sea level. None will likely meet the updated FAA criteria for commercial astronaut wings.
L-R: Oliver Daemen, Jeff Bezos, Mark Bezos & Wally Funk. Source: Blue OriginThe Blue Origin suborbital flight passengers in front of the New Shepard rocket that launched them into space and returned separately for a soft landing. Source: GeekWire / Alan Boyle
I’m looking forward to a day when suborbital flights are commonplace and orbital tourism is becoming a reality. This day is not far away.
Update 29 Sep 2021: Virgin Galactic cleared to resume flights
Virgin Galactic reported: “The FAA today advised Virgin Galactic that the corrective actions proposed by the Company have been accepted and conclude the FAA inquiry, which began August 11, 2021. They include:
Updated calculations to expand the protected airspace for future flights. Designating a larger area will ensure that Virgin Galactic has ample protected airspace for a variety of possible flight trajectories during spaceflight missions.
Additional steps into the Company’s flight procedures to ensure real-time mission notifications to FAA Air Traffic Control.”
Best wishes to Virgin Galactic and Blue Origin as they continue to develop their paths for private access to space.
Orbital Marine Power (https://orbitalmarine.com) is developing a large, moored tidal turbine, the O2, which they claim is the most powerful tidal turbine in the world. The O2 soon will be deployed at sea off the Orkney Islands, northeast of Scotland.
Rendering of the O2 tidal turbine. Source: Orbital Marine PowerSide view of the O2 tidal turbine. Source: Orbital Marine Power
Key features of the O2 tidal turbine are:
74 meter (243 ft) tubular steel hull with fore and aft mooring connections.
Hydraulically-actuated steel legs extending from the hull support the generator nacelles and rotors that are deployed underwater after the hull has been moored using a four-point mooring system.
Two 20 meter (65.6 ft) diameter, 2-bladed rotors give the O2 more than 600 m2 (6,458 ft2) of swept area to capture flowing tidal energy.
Blade pitch control enables bi-directional operation of the turbines with the hull in a fixed moored position (the hull doesn’t swing with the tide).
Each rotor drives a 1 MWe generator housed in the nacelle.
Power is delivered to shore by a submarine cable.
Here are three short videos that will give you a quick introduction to this remarkable machine:
“Orbital O2 2MW Tidal Turbine – World’s Most Powerful Tidal Turbine” (1:43 minutes), 2018 animation showing how the O2 design and how it will operate: https://www.youtube.com/watch?v=9hN3dBpPu8Q
O2 tidal turbine being moved in the shipyard in March 2021, prior to launch. The rotors are not yet attached to the nacelles.Source: Orbital Marine Power video screenshotO2 with the rotors attached in the water, under tow. Source: Orbital Marine Power
If the O2 demonstration proves to be successful, Orbital Marine Power plans to develop and deploy larger tidal turbines in the future.
So, what does the O2 tidal turbine have in common with an airship? The Aeromodeller II airship design developed by Belgian engineer Lieven Standaert implements an airborne mooring as a means to generate power using two wind turbines while remaining aloft.
Ground anchor enables propellers to function as wind turbines for power generation while tethered. Source: Inhabit.com
Rendering of Aeromodeller II shown tethered. Source: www.aeromodeller2.be
Both the O2 tidal turbine and the Aeromodeller II airship are buoyant vehicles in their respective media (water and air, respectively) and both are designed to extract power from that medium while moored (or tethered). Important differences are that the O2 tidal turbine is permanently moored and supplies power to users on land. The Aeromodeller II drops its anchor periodically to recharge its own power system while tethered and then raises its anchor to continue its journey. You’ll find more information on the Aeromodeller II airship in my separate article here: https://lynceans.org/wp-content/uploads/2019/08/Aeromodeller-2-converted1.pdf
After Paul Allen’s death on 15 October 2018, the Stratolaunch Systems company he founded lost the broad air launch business vision it had under his leadership. A year later, on October 2019, the private equity firm Cerberus Capital Management became the new owner of the firm renamed Stratolaunch, LLC. Another year later, in November 2021, Stratolaunch LLC announced its new air launch business vision with an initial focus on missions involving a prototype reusable hypersonic rocket plane called the Talon-A. Stratolaunch has engaged the aerospace firm Calspan (https://www.calspan.com/stratolaunch-testing/) to build and test models of the Talon-A. As described on the Stratolaunch LLC website (https://www.stratolaunch.com), Talon-A is only the first of a family of air-launched vehicles that will be developed to establish “a complete air-launch vehicle ecosystem.” It looks like Paul Allen’s broad air launch business vision still may be alive and well under new leadership.
In an important milestone for Stratolaunch LLC, their giant carrier aircraft, Roc, returned to the air for the second time from the Mojave Air and Space Port in southern California on 29 April 2021, more than two years after its first flight on 13 April 2019.
Stratolaunch’s Roc carrier plane during its second test flight on 29 April 2021. Source: StratolaunchStratolaunch’s Roc carrier plane during its second test flight on 29 April 2021. Source: StratolaunchThe Roc on its landing approach at Mojave Air and Space Port at the end of its second flight. Source: AP Photo/Matt Hartman
During its second flight on 29 April 2021, the Roc reached a maximum altitude of 14,000 feet (4,267 m) and a top speed of 199 mph (320 kph). The 28-wheel undercarriage remained extended for the whole flight.
At some point in the future, the Roc carrier aircraft test flight program will transition to captive carry flights with a Talon-A vehicle, followed by drop tests and finally actual flight tests of the hypersonic vehicle.
Stratolaunch explains that its Mach 6-class Talon-A vehicle is designed to make hypersonic testing more routine. They describe the Talon-A as follows:
“The Talon-A features a length of 28 feet (8.5 m), a wingspan of 11.3 feet (3.4 m), and a launch weight of approximately 6,000 pounds (2,722 Kg). It will conduct long duration flight at high Mach, and glide back for an autonomous, horizontal landing on a conventional runway. It will also be capable of autonomous takeoff, under its own power, via a conventional runway.”
Rendering of the Mach-6 Talon-A hypersonic vehicle in flight. Source: Stratolaunch
Beyond Talon-A, Stratolaunch is developing a larger hypersonic vehicle named Talon-Z. A longer-term objective is to develop the Black Ice fully reusable space plane that will be able to fly payloads and crew to orbit and return them to Earth for a landing at a conventional airport. The initial design will be optimized for unmanned cargo launch and return missions. A follow-on manned version will be optimized for transporting crews and cargo to and from orbit.
Stratolaunch’s planned family of aerospace vehicles is shown in the following graphic.
The Stratolaunch carrier vehicle, Roc, is shown with three hypersonic vehicles ready for launch. Below (L to R) are the Talon-Z and Talon-A hypersonic vehicles and the Black Ice orbital space plane. Source: Stratolaunch
If you’re interested, you can subscribe to the Stratolaunch newsletter on their website.
The World Air League is the organizer for a monumental airship race around the globe that will be held between September 2023 and May 2024. The World Air League describes their mission as follows:
“The mission and vision of the World Air League are to promote the advancement of lighter-than-air aviation for a sustainable future. The World Air League is creating the World Sky Race as an epic challenge to inspire inventors to invent and adventurers to compete. For strategic impact and purpose, the World Air League in embedding the World Sky Race® to be included in the global educational system to provide the world’s next-generation with a path to explore with their destination an alternate greener, cleaner future.”
The upcoming World Sky Race® will launch in September 2023 when the competing airships cross the Prime Meridian heading east over Greenwich, London, and will end eight months later in Paris in May 2024, after the competitors have circumnavigated the globe. During the eight-month race, the airships will be flying over 130+ UNESCO World Heritage Sites and cities. Hopefully this flying caravan will inspire people worldwide to the green transportation opportunities represented by modern airships. The following map shows the proposed route.
Source: World Air League
The following travel poster images provide inspiring views of some of the destinations that will be visited during the upcoming World Sky Race®.
Source: World Air League
The World Air League previously attempted to organize the inaugural World Sky Race® in 2010. That race didn’t occur. Hopefully the planned 2023 – 2024 race will become a reality and will be a rousing success.
Update, 26 October 2024:
The World Sky Race didn’t occur as scheduled and new dates for the event haven’t been announced. However, viable airship candidates for around-the-world flight are being developed and, in 2024, two airship manufacturers announced their plans for around-the-world flights later in this decade. Maybe there will be a World Sky Race in the future.
On 17 January 2021, Virgin Orbit conducted an airborne launch from their modified Boeing 747-400 “mothership,” Cosmic Girl, and their LauncherOne rocket boosted a payload of 10 small CubeSats into low Earth orbit. This marks the first commercial orbital mission for Virgin Orbit.
Cosmic Girl carrying a LauncherOne rocket takes off from Mojave Air and Space Port.Source: Virgin Orbit (above), AP Photo/Matt Hartman (below)Cosmic Girl performs the pre-launch pitch-up maneuver at an altitude of about 35,000 ft (10,688 m) during a test flight test on 12 April 2020. Source, three photos above: Virgin OrbitLaunch 17 January 2021. Source: Virgin Orbit
LauncherOne is a 70 foot long (21.34 meter), liquid fueled, two stage booster rocket that can deliver a 300 to 500 kg (661 to 1,102 lb) satellite payload to orbit. Due to the flexibility of using an airborne launch platform, the satellite can be placed into an orbit at any inclination between 0° (equatorial) to 120° (30° retrograde).
NASA sponsored the 10 CubeSats launched on 17 January under their Educational Launch of Nanosatellites (ELaNa) program. NASA also funded the launch under its Venture Class Launch Services (VCLS) program.
This was Virgin Orbit’s second attempt to launch satellites into orbit with LauncherOne. The first flight on 25 May 2020 failed due to a break in a propellant line for the first stage engine.
After Paul Allen’s death on 15 October 2018, the focus of Stratolaunch changed dramatically and Roc has remained grounded at the Mojave Air and Space Port since its first flight.
Roc on its first flight. Source: REUTERS/Gene Blevins/File Photo
It appears that, on 11 October 2019, Stratolaunch Systems was sold by its original holding company, Vulcan Inc., to an undisclosed new owner. Since then, Stratolaunch has put increased emphasis on using the Roc as an airborne launch platform for testing hypersonic vehicles. On 10 November 2020, Alan Boyle, writing for GeekWire , reported, “Today, Stratolaunch announced that it’s partnering with an aerospace research and development company called Calspan to build and test models of its Talon-A hypersonic vehicle, a reusable prototype rocket plane.”
Since 1990, Northrop Grumman Innovation Systems (formerly Orbital ATK and before that Orbital Sciences Corporation) has offered airborne launch services with their converted Stargazer L-1011 mothership and Pegasus booster rocket. From a launch altitude of about 40,000 ft (12,192 m), a three-stage Pegasus XL can carry satellites weighing up to 1,000 pounds (453.59 kg) into low-Earth orbit.
The L-1011 Stargazer carrying a Pegasus XL rocket. Source: Northrop Grumman
Festo is a German multinational industrial control and automation company based in Esslingen am Neckar, near Stuttgart. The Festo website is here: https://www.festo.com/group/en/cms/10054.htm
Festo reports that they invest about 8% of their revenues in research and development. Festo’s draws inspiration for some of its control and automation technology products from the natural world. To help facilitate this, Festo established the Bionic Learning Network, which is a research network linking Festo to universities, institutes, development companies and private inventors. A key goal of this network is to learn from nature and develop “new insights for technology and industrial applications”…. “in various fields, from safe automation and intelligent mechatronic solutions up to new drive and handling technologies, energy efficiency and lightweight construction.”
One of the challenges taken on by the Bionic Learning Network was to decipher how birds fly and then develop robotic devices that can implement that knowledge and fly like a bird. Their first product was the 2011 SmartBird and their newest product is the 2020 BionicSwift. In this article we’ll take a look at these two bionic birds and the significant advancements that Festo has made in just nine years.
2. SmartBird
On 24 March 2011, Festo issued a press release introducing their SmartBird flying bionic robot, which was one of their 2011 Bionic Learning Network projects. Festo reported:
“The research team from the family enterprise Festo has now, in 2011, succeeded in unraveling the mystery of bird flight. The key to its understanding is a unique movement that distinguishes SmartBird from all previous mechanical flapping wing constructions and allows the ultra-lightweight, powerful flight model to take off, fly and land autonomously.”
“SmartBird flies, glides and sails through the air just like its natural model – the Herring Gull – with no additional drive mechanism. Its wings not only beat up and down, but also twist at specific angles. This is made possible by an active articulated torsional drive unit, which in combination with a complex control system makes for unprecedented efficiency in flight operation. Festo has thus succeeded for the first time in attaining an energy-efficient technical adaptation of this model from nature.”
SmartBird measures 1.07 meters (42 in) long with a wingspan of 2.0 meters (79 in) and a weigh of 450 grams (16 ounces, 1 pound). This is about a 1.6X scale-up in the length and span of an actual Herring Gull, but at about one-third the weight. It is capable of autonomous takeoff, flight, and landing using just its wings, and it controls itself the same way birds do, by twisting its body, wings, and tail. SmartBird’s propulsion system has a power requirement of 23 watts.
On 1 July 2020, Festo introduced the BionicSwift as their latest ultra light flying bionic robot that mimics how actual birds fly.
The BionicSwift, inspired by a Common Swift, measures 44.5 cm (17.5 in) long with a wingspan of 68 cm (26.7 in) and a weight of just 42 grams (1.5 ounces). It’s approximately a 2X scale-up of a Common Swift, but still a remarkably compact, yet complex flying machine with aerodynamic plumage that closely replicates the flight feathers on an actual Swift. The 2011 SmartBird was more than twice the physical size and ten times heavier.
The BionicSwift is agile, nimble and can even fly loops and tight turns. Festo reports: “Due to this close-to-nature replica of the wings, the BionicSwifts have a better flight profile than previous wing-beating drives.” Compare the complex, feathered wing structure in the following Festo photos of the BionicSwift with the previous photos showing the simpler, solid wing structure of the 2011 SmartBird.
Source: All three BionicSwift photos from Festo
A BionicSwift can fly singly or in coordinated flight with a group of other BionicSwifts. Festo describes how this works: “Radio-based indoor GPS with ultra wideband technology (UWB) enables the coordinated and safe flying of the BionicSwifts. For this purpose, several radio modules are installed in one room. These anchors then locate each other and define the controlled airspace. Each robotic bird is also equipped with a radio marker. This sends signals to the anchors, which can then locate the exact position of the bird and send the collected data to a central master computer, which acts as a navigation system.” Flying time is about seven minutes per battery charge.
4. For more information about other Festo bionic creations:
I encourage you to visit the Festo BionIc Learning Network webpage at the following link and browse the resources available for the many intriguing projects. https://www.festo.com/group/en/cms/10156.htm
On this webpage you’ll find a series of links listed under the heading “More Projects,” which will introduce you to the wide range of Bionic Learning Network projects since 2006.
You also can watch the following YouTube short videos of Festo’s many bionic creations:
BionicFinWave (2018):replicates the swimming movements of sea creatures with undulating fins to create a unique fin drive system for an autonomous underwater vehicle: https://www.youtube.com/watch?v=fRNq55EbnZc
AirRay (2010): replicates the natural underwater movements of a Manta Ray in a larger-than-life, neutrally buoyant, ray-shaped airship with a flapping wing drive: https://www.youtube.com/watch?v=c3-wIICjAhE
AquaRay (2010): replicates the natural underwater movements of a Manta Ray in a full-size autonomous underwater vehicle with a flapping wing drive: https://www.youtube.com/watch?v=F4-6oNagIvk
AirPenguin (2009): replicates the natural underwater movements of a penguin in a larger-than-life, neutrally buoyant, penguin-shaped airship: https://www.youtube.com/watch?v=jPGgl5VH5go
AquaPenguin (2009): replicates the natural underwater movements of a penguin in a small penguin-sized autonomous underwater vehicle: https://www.youtube.com/watch?v=u8tfES8gImc
AirJelly (2008): replicates the natural underwater movements of a jelly fish in a larger-than-life, neutrally buoyant, jelly fish-shaped airship: https://www.youtube.com/watch?v=divLsTtA5vk
AquaJelly (2008): replicates the natural underwater movements of a jelly fish in a small, autonomous, peristaltic drive autonomous underwater vehicle that can operate in coordination with several other AquaJellies: https://www.youtube.com/watch?v=N-O8-N71Qcw
Peter Lobner, updated 6 November 2024 (post-Rev. 6)
1. Introduction
Modern Airships is a three-part document that contains an overview of modern airship and aerostat technology in Part 1 and links in Parts 1, 2 and 3 to more than 285 individual articles on historic and advanced airship designs. This is Part 1. Here are the links to the other two parts:
To help you navigate the large volume of material in these three documents, please refer to following indexes. The first index simply lists the article titles in alphabetic order within each Part.
Parts 1 & 2 address similar types of airships and unpowered aerostats. The following airship type index enables you to see all of the airships and aerostats addressed in Parts 1 & 2, grouped by type, with direct links to the relevant articles.
The airships described in Part 3 are relatively exotic concepts in comparison to the more utilitarian and heavy-lift airships that dominate Parts 1 and 2. As shown in the following index, the airships in Part 3 are organized by function rather than airship type, which sometimes is difficult to determine with the information available.
Modern Airships – Part 1 begins with an overview of modern airship and aerostat technology, continues with a graphic table that identifies the airships addressed in this part, and concludes by providing links to more than 100 individual articles on these airships. A downloadable pdf copy of Part 1 is available here:
If you have any comments or wish to identify errors in this document, please send me an e-mail to: [email protected].
I hope you’ll find the Modern Airships series to be informative, useful, and different from any other single document on this subject.
Best regards,
Peter Lobner
6 November 2024
Record of revisions to Part 1
Original Modern Airships post, 26 August 2016: addressed 14 airships in a single post.
Expanded the Modern Airships post and split it into three parts, 18 August 2019: Part 1 included 22 linked articles.
Part 1, Revision 1, 21 December 2020: Added 15 new articles, split the existing Aeros article into two articles and updated all of the original articles. Part 1 now had 38 articles.
Part 1, Revision 2, 3 April 2021: Updated the main text and 10 existing articles, and expanded and reorganized the graphic tables. Part 1 still had 38 articles
Part 1, Revision 3, 26 August 2021: Added 34 new articles, split the existing Helistat article into five articles and the Aereon article into two articles, and expanded and reorganized the graphic tables. Also updated 23 existing articles. Part 1 now had 77 articles.
Part 1, Revision 4, 12 February 2022: Added 12 new articles, split the existing Airlander article into two updated articles (prototype, production), moved Halo to Part 3, expanded the graphic tables and updated 17 additional existing articles. A detailed summary of changes incorporated in Part 1 Rev 4 is listed here. Part 1 now had 89 articles.
Part 1, Revision 5, 10 March 2022: Added 2 new articles, split rigid & semi-rigid airships in the graphic tables, and updated 58 existing articles. With this revision, all Part 1 linked articles have been updated in February or March 2022. A detailed summary of changes incorporated in Part 1 Rev 5 is listed here. Part 1 now has 91 articles.
Part 1, Revision 6, 17 March 2024: This revision includes a major reorganization of Parts 1 & 2 to better aggregate airships and unpowered aerostats by type, with a corresponding reorganization of the graphic tables. Over the past two years, 15 new articles were added to Part 1 and 28 articles were updated. In the final changes for Rev. 6, several articles were moved between Parts 1 & 2. A detailed summary of changes incorporated in Part 1 Rev 6 is listed here. Part 1 now has 107 articles.
Part 1, changes since Rev. 6 (17 March 2024)
New articles:
None yet
Updated articles:
LTA Research and Exploration – 8 July 2024
AT2 Aerospace – 17 September 2024
Lockheed Martin – P-791 – 30 September 2024
Lockheed Martin – Sky Tug and LMH-1 – 30 September 2024
Hybrid Air Vehicles (HAV) / Northrop Grumman – HAV-3 and HAV-304 (LEMV) – 2 October 2024
Hybrid Air Vehicles (HAV) – Airlander 10 prototype – 2 October 2024
Walden Aerospace / LTAS / LTASI – Lenticular, toroidal, variable buoyancy airships – 18 October 2024, 5 November 2024
SAIC – Skybus 1500 – 6 November 2024
Airship Industries Ltd. – 6 November 2024
2. Well-established benefits and opportunities, but a risk-averse market
For several decades, there has been significant interest in the use of modern lighter-than-air craft and hybrid airships in a variety of military, commercial and other roles, including:
Heavy cargo carriers operating point-to-point between manufacturer and end-user, eliminating inter-modal load transfers enroute
Heavy cargo carriers serving remote and/or unimproved sites not adequately served by other modes of transportation
Disaster relief, particularly in areas not easily accessible by other means
Persistent optionally-manned surveillance platforms for military intelligence, surveillance & reconnaissance (ISR), maritime surveillance, border patrol, search and rescue
Passenger airships
Commercial flying cruise liner / flying hotel
Airship yacht
Personal airship
Drone carrier
High altitude regional communications node
One of the very significant factors driving interest in modern airships is that they offer the potential to link isolated regions with the rest of the world while doing so in a way that should have lower environmental impacts than other transportation alternatives for those regions. This target market for airships exists in more than two-thirds of the world’s land area where more than half the world’s population live without direct access to paved roads and reliable ground transportation.
In spite of the significant interest and the development of many promising airship designs, an actual worldwide airship cargo and passenger transportation industry has been very slow in developing. To give you an example of how slow:
As of November 2023, other than a modest number of commercially certified blimps used largely as advertising platforms, the Zeppelin NT 07 is the only advanced airship that has been certified and is flying regularly in commercial passenger service.
At the March 2019 Aviation Innovations Conference – Cargo Airships in Toronto, Canada, Solar Ship CEO Jay Godsall proposed an industry-wide challenge to actually demonstrate by July 2021 airships that can move a 3 metric ton (6,614 lb) standard 20 foot intermodal container configured as a mobile medical lab 300 km (186 mi) to a remote location. Godsall noted that this capability would be of great value if it did exist, for example, in support of relief efforts in Africa and other regions of the world.
So in spite of the airship industry having developed many designs capable of transporting 10’s to 100’s of tons of cargo thousands of miles, today there is not a single airship than can transport a 3 metric ton (6,614 lb) payload 300 km (186 mi).
Why has the airship industry been so slow to develop? The bottom line has been a persistent lack of funding. With many manufacturers having invested in developing advanced designs in varying levels of detail, the first to secure adequate funding will be able to take the next steps to build and certify a manufacturing facility, build and flight test a full-scale prototype airship, complete the airship type certification process, and start offering a certified airship for sale.
There are some significant roadblocks in the way:
No full-scale prototypes are flying: Many airship firms currently have little more than slide presentations to show to potential investors and customers. There are few sub-scale airship demonstrators, but no full-scale prototypes. The airship firms are depending on potential investors and customers making a “leap of faith” that the “paper” airship actually can be delivered. However, this situation will change significantly in the next few years as several airship manufacturers (i.e., LTA Research and Exploration, Flying Whales and Hybrid Air Vehicles) finally complete their full-scale, large airship prototypes and commence flight testing.
Immature manufacturing capability: While the airship industry has been good at developing many advanced designs, some claiming to exist as “construction-ready” plans, few airship firms are in the process of building an airship factory. The industrial scale-up factor for an airship firm to go from the design and engineering facilities existing today to the facilities needed for series production of full-scale airships is huge. LTA Research and Exploration is one of the few firms with access to modernized large airship hangars (the former Goodyear Airdock in Akron OH and the former Navy airship hangars at Moffett Field, CA) for use as manufacturing facilities. In 2016, Russian airship manufacturer Augur RosAeroSystems proposed building a new factory to manufacture up to 10 ATLANT airships per year. The funding requirement for that factory was estimated at $157 million. The exact amount isn’t important. No matter how you look at it, it’s a big number. Large investments are needed for any airship firm to become a viable manufacturer.
Significant financial risk: The amount of funding needed by airship firms to make the next steps toward becoming a viable manufacturer exceeds the amount available from venture capitalists who are willing to accept significant risk. Private equity sources typically are risk averse. Public sources, or public-private partnerships, have been slow to develop an interest in the airship industry. The French airship firm Flying Whales appears to be the first to have gained access to significant funding from public institutions.
Significant regulatory risk: Current US, Canadian and European airship regulations were developed for non-rigid blimps and they fail to address how to certify most of the advanced airships currently under development. This means that the first airship manufacturers seeking type certificates for advanced airships will face uphill battles as they have to deal with aviation regulatory authorities struggling to fill in the big gaps in their regulatory framework and set precedents for later applicants. It is incumbent on the aviation regulatory authorities to get updated regulations in place in a timely manner and make the regulatory process predictable for existing and future applicants.
No airship operational infrastructure: There is nothing existing today that is intended to support the operation of new commercial airships tomorrow. The early airship operators will need to develop operating bases, hangar facilities, maintenance facilities, airship routes, and commercial arrangements for cargo and passengers. While many airship manufacturers boast that their designs can operate from unimproved sites without most or all of the traditional ground infrastructure required by zeppelins and blimps, the fact of the matter is that not all advanced airships will be operating from dirt fields and parked outside when not flying. There is real infrastructure to be built, and this will require a significant investment by the airship operators.
Steep learning curve for potential customers: Only the operators of the Zeppelin NT have experience in operating a modern airship today. The process for integrating airship operations and maintenance into a customer’s business work flow has more than a few unknowns. With the lack of modern airship operational experience, there are no testimonials or help lines to support a new customer. They’ll have to work out the details with only limited support. Ten years from now, the situation should be vastly improved, but for the first operators, it will be a challenge.
Few qualified pilots and crew: The airship manufacturers will need to work with the aviation regulatory authorities and develop programs for training and licensing new pilots and crew. The British airship manufacturer Varialift has stated that one of the roles of their ARH-PT prototype will be to train future pilots.
This uncertain business climate for airships seems likely to change in the mid-to-late 2020s, when several different heavy-lift and passenger airships are expected to be certified by airworthiness authorities and ready for series production and sale to interested customers. If customers step up and place significant orders, we may be able to realize the promise of airship travel and its potential to change our world in many positive ways.
3. Status of current aviation regulations for airships
As noted previously, current aviation regulations have not kept pace with the development of modern airship technology. In this section, we’ll take a look at the current regulations.
US Federal Aviation Administration (FAA)
In the US, the FAA’s current requirements for airships are defined in the document FAA-P-8110-2, Change 2, “Airship Design Criteria (ADC),” dated 6 February 1995, which is available here:
The ADC applies to non-rigid, near-equilibrium, conventional airships with seating for nine passengers or less, excluding the pilot, and it serves as the basis for issuing the type certificate required before a particular airship type can enter commercial service in the US. The limited scope of this current regulation is highlighted by the following definitions contained in the ADC:
Airship: an engine-driven, lighter-than-air aircraft, than can be steered.
Non-rigid: an airship whose structural integrity and shape is maintained by the pressure of the gas contained within the envelope.
Near-equilibrium: an airship that is capable of achieving zero static heaviness during normal flight operations.
Supplementary guidance for non-rigid, near-equilibrium, conventional airships is provided in FAA Advisory Circular (AC) No. 21.17-1A, “Type Certification – Airships,” dated 25 September 1992, which is available here:
The FAA’s ADC and the associated AC were written for blimps, not for the range of modern airships under development today. For example, aerostatic lift is only one component of lift in modern hybrid airships, which also depend on powered lift from engines and aerodynamic lift during forward flight. Hybrid airships are not “lighter-than-air” and cannot achieve zero static heaviness during normal operations, yet they are an important class of airships being developed in several countries. In addition, almost all modern airships, except blimps, have rigid or semi-rigid structures that enable them to carry heavy loads and mount powerful engines on locations other than the gondola of a non-rigid airship.
On March 12, 2012 the FAA announced that Lockheed Martin Aeronautics submitted an application for type certification for their model LMZ1M (LMH-1), which is “a manned cargo lifting hybrid airship incorporating a number of advanced features.” The FAA assigned that application to their docket number FAA-2013-0550.
To address the gap in airship regulations head-on, Lockheed Martin submitted to the FAA their recommended criteria document, “Hybrid Certification Criteria (HCC) for Transport Category Hybrid Airships,” which is a 206 page document developed specifically for the LMZ1M (LMH-1). The HCC is also known as Lockheed Martin Aeronautics Company Document Number 1008D0122, Rev. C, dated 31 January 2013. You can download the HCC document and related public docketed items on the FAA website here:
In November 2015, Lockheed Martin announced that the FAA’s Seattle Aircraft Certification Office had approved the project-specific certification plan for the LMZ1M (LMH-1). At the time Lockheed Martin transitioned their hybrid airship business to AT2 Aerospace in May 2023, their hybrid airship had not yet been type certified.
Germany & Netherlands
Recognizing the absence of an adequate regulatory framework for modern airships, civil aviation authorities of Germany and Netherlands developed supplementary guidance to the European Joint Aviation Requirements (JAR-25) and the FAA’s ADC for a category of airships called “Transport Airships,” which they define as follows:
“The transport category is defined for multi-engine propeller driven airships that have a capacity of 20 or more passengers (excluding crew), or a maximum take-off mass of 15,000 kg or more, or a design lifting gas volume of 20,000 m3 or more, whichever is greater.”
On 11 February 2021, the European Union Aviation Safety Agency (EASA) proposed a new regulatory framework for the certification of large airships. The proposed document went through a public review and comment period before the final document was issued on 21 January 2022 as Doc. No. SC GAS, “Special Condition ‘SC GAS’ Gas Airships,” which is available here: https://www.easa.europa.eu/downloads/134946/en
EASA explained their rationale for this special condition document:
“EASA has received applications for the type certification of large Airships but has not yet published Certification Specifications (CS) for these products…… In the absence of agreed and published certification specifications for Airships by EASA…….a complete set of dedicated technical specifications in the form of a Special Condition for Gas Airships has been developed. This Special Condition addresses the unique characteristics of Airships and defines airworthiness specifications that may be used to demonstrate compliance with the essential requirements in Annex II of regulation (EU) 2018/1139 of the European Parliament and Council. That is required before the issuance of the EASA type certificate, as well as for the approval of later changes to type certificate.”
“The Special Condition is a high-level set of objective driven and performance-based requirements. It was developed in close cooperation with the industry working group. The Special Condition addresses two designs, one being a 260,000 m3 rigid equilibrium Airship for cargo operations, the other one a 45,000 m3 non-rigid hybrid Airship for up to 100 passengers. However, the authors believe the SC can be applied to all manned Airships with non-pressurized crew or passenger compartments. It will be subject to EASA Certification Team agreement whether this Special Condition can be deemed sufficient as a Certification Basis, for example unmanned designs are not sufficiently addressed by this proposal. Due to the low number of projects no categories have been established. The different safety levels applicable to specific Airship designs will be addressed through the Means of Compliance (MOC).”
The EASA is ahead of the FAA in terms of having published usable interim regulations for advanced airships. However, both EASA and FAA regulators are lagging the development of advanced civilian airship designs that may be submitted for type certification in the next decade. The lack of mature regulations for advanced airship designs will increase the regulatory risk for the designers / manufacturers of those airships.
4. Lifting gas
In the US, Europe and Canada, the following aviation regulations only allow the use of non-flammable lifting gas:
FAA ADC: “The lifting gas must be non-flammable.” (4.48)
TAR: “The lifting gas must be non-flammable, non-toxic and non-irritant.” (TAR 893)
Canadian Air Regulations: “Hydrogen is not an acceptable lifting gas for use in airships.” (541.7)
The EASA proposed Special Condition issued on 21 January 2022 creates an opportunity to use flammable lifting gases, subject to the following conditions:
SC GAS.2355 Lifting gas system
Lifting gas systems required for the safe operation of the Airship must:
withstand all loading conditions expected in operation including emergency conditions
monitor and control lifting performance and degradation
If the lifting gas is toxic, irritant or flammable, adequate measures must be taken in design and operation to ensure the safety of the occupants and people on the ground in all envisaged ground and flight conditions including emergency conditions.
SC GAS.2340 Electrostatic Discharge
There must be appropriate electrostatic discharge means in the design of each Airship whose lift-producing medium contains a flammable gas to ensure that the effects of electrostatic discharge will not create a hazard.
SC GAS.2325 Fire Protection
The design must minimize the risk of fire initiation caused by:
Anticipated heat or energy dissipation or system failures or overheat that are expected to generate heat sufficient to ignite a fire;
Ignition of flammable fluids, gases or vapors; and
Fire propagating or initiating system characteristics (e.g. oxygen systems); and
A survivable emergency landing.
Without hydrogen, the remaining practical choices for lifting gas are helium and hot air. A given volume of hot air can lift only about one-third as much as the same volume of helium, making helium the near-universal choice, with hot air being relegated to a few, small thermal airships and larger thermal-gas (Rozière) airships.
The current high price of helium is a factor in the renewed interest in hydrogen as a lifting gas. It’s also a key selling point for thermal airships. Most helium is produced as a byproduct from natural gas production, hence, helium is not “rare.” However, only a very small fraction of helium available in natural gas currently is recovered, on the order of 1.25%. The remainder is released to the atmosphere. The helium recovery rate could be higher, but is not warranted by the current market for helium. Helium is difficult to store. The cost of transportation to end-users is a big fraction of the market price of helium.
Hydrogen provides 10% more lift than helium. It can be manufactured easily at low cost and can be stored. If needed, hydrogen can be produced with simple equipment in the field. This could be an important capability for recovering an airship damaged and grounded in a remote region. One airship concept described in Modern Airships – Part 3, the Aeromodeller II, is designed for using hydrogen as the lifting gas and as a clean fuel (zero greenhouse gases produced) for its propulsion engines. A unique feature of this airship concept is an on-board system to generate more hydrogen when needed from the electrolysis of water ballast.
A technique for preventing hydrogen flammability is described in Russian patent RU2441685C2, “Gas compound used to prevent inflammation and explosion of hydrogen-air mixtures,” which was filed in 2010 and granted in 2012. This technique appears to be applicable to an airship using hydrogen as its lifting gas. You can read the patent at the following link: https://patents.google.com/patent/RU2441685C2/en
The Canadian airship firm Buoyant Aircraft Systems International (BASI) is a proponent of using hydrogen lifting gas. Anticipating a future opportunity to use hydrogen, they have designed their lifting gas cells to be able to operate with either helium or hydrogen.
Additional regulatory changes will be required to permit the general use of hydrogen in aviation. With the growing interest in the use of hydrogen fuel in aviation, it seems only a matter of time before it is approved for use as a lifting gas in commercial airships.
Even with the needed regulatory changes, the insurance industry will have to deal with the matter of insuring a hydrogen-filled airship.
5. Types of modern airships and aerostats
The term “aerostat” broadly includes all lighter than air vehicles that gain lift through the use of a buoyant gas. Aerostats include unpowered balloons (tethered or free-flying) and powered airships. The following types of airships are described in the Modern Airships series of documents:
Conventional airships are lighter-than-air (LTA) vehicles that operate at or near neutral buoyancy. The lifting gas (helium) generates approximately 100% of the lift at low speed, thereby permitting vertical takeoff and landing (VTOL) operations and hovering with little or no lift contribution from the propulsion / maneuvering system. Various types of propulsors may be used for cruise flight propulsion and for low-speed maneuvering and station keeping.
Airships of this type include rigid zeppelins, semi-rigid airships and non-rigid blimps.
Rigid airships: These airships have a lightweight, rigid airframe with an outer skin that defines their exterior shape. The airframe supports the gondola, engines and payload. Most have atmospheric pressure lifting gas cells located within the rigid airframe. A special case is a metal-clad rigid airship, with a metal hull that is self-supporting at atmospheric pressure, but typically operates with a slightly positive internal pressure.
Semi-rigid airships: These airships have a rigid structural framework (i.e., a keel or an internal framework) that supports loads and is connected via a load distribution system to a flexible, pressure-stabilized envelope that defines the exterior shape and typically contains air ballonets.
Non-rigid airships (blimps): These airships have a pressure-stabilized, flexible envelope that defines the exterior shape of the airship and typically contains air ballonets. There is no keel or internal structure. Most loads are attached to the gondola and are transferred via a load distribution system to the envelope.
The LTA Research and Exploration Pathfinder 1 and the Flying Whales LCA60T are examples of conventional rigid airships.
The Zeppelin NT and the SkyLifter are examples of conventional semi-rigid airships.
The Aeros 40D Sky Dragon and the American Blimp Corporation MZ-3A (A-170G) are examples of conventional non-rigid airships (blimps).
After being loaded and ballasted before flight, conventional airships have various means to exercise in-flight control over their aerostatic buoyancy, internal pressure and trim. Buoyancy control is exercised with ballast and lifting gas. Internal pressure is controlled with air ballonets and lifting gas vents. Trim is adjusted with the air ballonets or moveable ballast.
Conventional airships with thrust vectoring propulsors have the ability to operate with some degree of net aerostatic heaviness or lightness that can be compensated for with the dynamic thrust (lift or downforce) from the adjustable propulsors.
Controlling buoyancy with ballast
Many conventional airships require adjustable ballast (i.e., typically water or sand) that can be added or removed as needed to establish a desired net buoyancy before flight. Load exchanges (i.e., taking on or discharging cargo or passengers) can change the overall mass of an airship and may require a corresponding ballast adjustment during or after the load exchange.
In-flight use of fuel and other consumables can change the overall mass of an airship. The primary combustion products of diesel fuel are water and carbon dioxide. To reduce the loss of mass from fuel consumption, some airships use a rather complex system to recover water from the engine exhaust. A modern diesel engine water recovery system being developed for the Aerovehicles AV-10 blimp is expected to recover 60% to 70% of the weight of the fuel burned, significantly reducing the change in airship mass during a long mission.
Some Navy blimps and other long-range airships have had a hoist system that could be used in flight to retrieve water from the ocean or any other body of water to increase the amount of on-board ballast.
If an airship becomes heavy, ballast can be dumped in flight to increase aerostatic buoyancy.
Controlling buoyancy with lifting gas
The lifting gas inside an airship may be at atmospheric pressure (most rigid airships) or at a pressure slightly greater than atmospheric (semi-rigid and non-rigid airships). Normally, there is no significant loss (leakage) of lifting gas to the environment. A given mass of lifting gas will create a constant lift force, regardless of pressure or altitude, when the lifting gas is at equal pressure and temperature with the surrounding air. Therefore, a change in altitude will not change the aerostatic lift.
However, temperature differentials between the lifting gas and the ambient air will affect the aerostatic lift produced by the lifting gas. To exploit this behavior, some airships can control buoyancy using lifting gas heaters / coolers to manage gas temperature.
The lifting gas heaters are important for operation in the Arctic, where a cold-soak in nighttime temperatures may result in the lifting gas temperature lagging behind daytime ambient air temperature. This temperature differential would result in a loss of lift until lifting gas and ambient air temperatures were equal.
Conversely, operating an airship in hot regions can result in the lifting gas temperature rising above ambient air temperature (the lifting gas becomes “superheated”), thereby increasing buoyancy. To restore buoyancy in this case, some airships have coolers (i.e., helium-to-air heat exchangers) in the lifting gas cells to remove heat from the lifting gas.
As described by Boyle’s Law, pressure (P) and gas volume (V) are inversely proportional at a constant temperature according to the following relationship: PV = K, where K is a constant. As an airship ascends, atmospheric pressure decreases. This means that a fixed mass of lifting gas will expand within the lifting gas cells during ascent, and will contract within the lifting gas cells during descent. As described previously, this lifting gas expansion and contraction does not affect the magnitude of the aerostatic lift as long as the lifting gas is at equal pressure and temperature with the surrounding air.
If an airship is light and the desired buoyancy cannot be restored with lifting gas coolers, it is possible to vent some lifting gas to the atmosphere to decrease aerostatic lift. Usually there are two types of vents: a manually-operated vent controlled by the pilot and an automatically-operated safety vent designed to protect the envelope from overpressure.
Role of the ballonets
The airship hull / envelope is divided into one or more sealed lifting gas volumes and separate gas volumes called “ballonets” that contain air at ambient, or near-ambient pressure. The ballonets serve as the expansion space that is available for the lifting gas cells as the airship ascends.
The ratio of the total envelope volume to the total ballonet volume is a measure of the expansion space for the lifting gas and is a key factor in determining the airship’s “pressure altitude.” This is the altitude at which the lifting gas cells are fully expanded, and the ballonets are empty. For example, with an envelope volume of 8,255 m3 (290,450 ft3) and a ballonet volume of 2,000 m3 (71,000 ft3), or about 24% of the envelope volume, a Zeppelin NT semi-rigid airship has a reported maximum altitude of 3,000 m (9,842 ft), with the envelope positive pressure of 5 mbar. With a smaller ballonet volume, the Zeppelin NT would have a lower maximum altitude at the specified internal pressure.
In semi-rigid and non-rigid airships with pressure-stabilized hulls, the ballonets are part of the airship’s pressure control system, which automatically maintains the envelope pressure in a desired range. Pressure control is accomplished by changing the volume of the ballonets. An air induction system draws atmospheric air and delivers it at a slight positive pressure (relative to envelope pressure) to increase ballonet volume. An air vent system will discharge air from the ballonets to the ambient atmosphere. While there is a change in mass during these ballonet operations, it is relatively small and does not significantly affect the aerostatic buoyancy of the airship.
Fore and aft ballonets can be operated individually to adjust the trim (pitch angle) of the airship. Inflating only the fore or aft ballonet, and allowing the opposite ballonet to deflate, will make the bow or stern of the airship slightly heavier and change the pitch angle of the airship without significantly affecting the overall aerostatic buoyancy. These ballonet operating principles are shown in the following diagrams of a blimp with two ballonets, which are shown in blue.
Blimp with two ballonets (blue). Top diagram shows airship with both ballonets full for level cruise flight at low altitude. The middle diagram shows the forward ballonet full and the aft ballonet empty, creating a slightly nose-heavy condition for descending flight. The bottom diagram shows the forward ballonet empty and the aft ballonet full, creating a slightly tail-heavy condition for ascending flight.Source: zeppelinfan.de
5.2 Variable buoyancy airships
Variable buoyancy airships can change their net lift, or “static heaviness,” to become lighter-than-air, neutrally buoyant or heavier-than-air as the circumstances require. Basic characteristics of variable buoyancy airships include the following:
Variable buoyancy airships are capable of VTOL operations and hovering, usually with a full load.
The buoyancy control system may enable in-flight load exchanges from a hovering airship without the need for external ballast.
On the ground, variable buoyancy airships can make themselves heavier-than-air to facilitate load exchanges without the need for external infrastructure or ballast.
It is not necessary for a “light” airship to vent the lifting gas to the atmosphere.
Variable buoyancy, fixed volume airships
Variable buoyancy commonly is implemented by adjusting the density of the lifting gas or a ballast gas, and thereby changing the static heaviness of a fixed volume airship. This also is referred to as density-controlled buoyancy (DCB). For example, a variable buoyancy / fixed volume airship can become heavier by compressing the helium lifting gas or ambient air ballast:
Compressing some of the helium lifting gas into smaller volume tanks aboard the airship reduces the total mass of helium available to generate aerostatic lift.
Compressing ambient air into pressurized tanks aboard the airship adds mass (ballast) to the airship and thus decreases the net lift.
The airship becomes lighter by venting the pressurized gas tanks:
Compressed helium lifting gas is vented back into the helium lifting gas cells, increasing the mass of helium available to generate aerostatic lift.
Compressed air is vented to the atmosphere, reducing the mass of the airship and thus increasing net lift.
The Aeros Aeroscraft Dragon Dream and the Varilift ARH-50 are examples of variable buoyancy / fixed volume airships.
Instead of using a low-density gas to generate aerostatic lift, a vacuum airship uses very low-density air (a partial vacuum) to generate lift, which can be controlled by managing the vacuum conditions inside lightweight, fixed volume structures capable of retaining the vacuum. The key challenge is making the variable vacuum containment and associated systems light enough to generate net lift. Once that has been achieved, then the challenge will be to package that variable buoyancy / variable vacuum system into a functional airship. These challenges have been accepted by Anumá Aerospace and by engineer Ilia Toli.
Variable buoyancy, variable volume airships
Variable buoyancy also can be implemented by adjusting the total volume of the helium envelope without changing the mass of helium in the envelope.
As the size of the helium envelope increases, the airship displaces more air and the buoyant force of the atmosphere acting on the airship increases. Static heaviness decreases.
As the size of the helium envelope decreases, the airship displaces less air and the buoyant force of the atmosphere acting on the airship decreases. Static heaviness increases.
The concept for a variable buoyancy / variable volume airship seems to have originated in the mid-1970s with inventor Arthur Clyde Davenport and the firm Dynapods, Inc. The tri-lobe Voliris airships and the EADS Tropospheric Airship are modern examples of variable buoyancy / variable volume airships.
This buoyancy control concept was developed and applied in the 1700s in hybrid balloons designed by Jean-François Pilâtre de Rozière. Such “Rozière” balloons have separate chambers for a non-heated lift gas (hydrogen or helium) and a heated lift gas (air). This concept has been carried over into airships. With helium alone the airship is semi-buoyant (heavier-than-air). Buoyancy is managed by controlling the heating and cooling of the air in a separate “thermal volume.” Examples of hybrid thermal (Rozière) airships are the British Thermo-Skyship (circa 1970s to early 1980s), Russian Thermoplane ALA-40 (circa 1980s to early 1990s), and the heavy-lift Aerosmena (AIDBA) “aeroplatform” currently being developed in Russia. All are lenticular (lens-shaped) airships.
Variable buoyancy propulsion airships / aircraft
Back in the 1860s, Dr. Solomon Andrews invented the directionally maneuverable, hydrogen-filled airship named Aereon that used variable buoyancy (VB) and airflow around the airship’s gas envelope to provide propulsion without an engine.
VB propulsion airships / aircraft fly a repeating sinusoidal flight profile in which they gain altitude as positively buoyant hybrid airships, then decrease their buoyancy at some maximum altitude and continue to fly under the influence of gravity as a semi-buoyant glider. After gradually losing altitude during a long glide, the pilot increases buoyancy and starts the climb back to higher altitude in the next cycle.
The UK’s Phoenix and Michael Walden’s HY-SOAR BAT concept are two examples of variable buoyancy propulsion airships / aircraft.
5.3 Semi-buoyant, hybrid air vehicles
Semi-buoyant, hybrid airships
Hybrid airships are heavier-than-air (HTA) vehicles. The term “semi-buoyant” means that the lifting gas provides only a fraction of the needed lift (typically 60 – 80%) and the balance of the lift needed for flight is generated by other means, such as vectored thrust engines and aerodynamic lift from the fuselage and wings during forward flight.
Sources of lift for a semi-rigid, hybrid airship. Source: DoD 2012
Basic characteristics of hybrid airships include the following:
This type of airship requires some airspeed to generate aerodynamic lift. Therefore, it typically makes a short takeoff and landing (STOL).
Some hybrid airships may be capable of limited VTOL operations (i.e., when lightly loaded, or when equipped with powerful vectored thrust engines).
Like conventional airships, the gas envelope in hybrid airship is divided into one or more lifting gas volumes and separate ballonet volumes containing ambient air.
Hybrid airships are heavier-than-air and are easier to control on the ground than conventional airships.
There are three types of hybrid airships: non-rigid, semi-rigid and rigid.
Non-rigid hybrid airships: This type of hybrid airship has a pressure-stabilized, flexible, multi-layer fabric gas envelope that would collapse if the internal pressure were lost. Catenary curtains inside the gas envelope support a gondola and distribute loads into the upper surfaces of the envelope. Ballonets control the pressure inside the gas envelope and can be used to control pitch angle, as on conventional blimps. The wide hybrid airships may have separate ballonets on each side of the inflated envelope that can be used to adjust the roll angle.
Semi-rigid hybrid airships: This type of hybrid airship has a substantial load-carrying, rigid structure, which may be a large keel or a more complex rigid framework inside the gas envelope, that is connected via a load distribution system to the flexible, pressurized envelope that defines the exterior shape and contains air ballonets.
Rigid hybrid airships: This type of hybrid airship has a substantial rigid structure that defines the shape of the exterior aeroshell. The “hard” skin of the airship may be better suited for operation in Arctic conditions, where snow loads and high winds might challenge the integrity of a pressure-stabilized gas envelope on a non-rigid or semi-rigid airship.
The AT2 Aerospace Z1 and the HAV Airlander 10 are examples of large hybrid airships that are under development in 2023. Their propulsion engines are attached directly to reinforced areas of the fabric gas envelope and are supported by localized load distribution systems (i.e., distributed cable stays). Their gas envelopes have no rigid internal structures, and in that respect they resemble blimps.
The Lockheed Martin Aerocraft is an example of a semi-rigid hybrid airship with a substantial, load-carrying, internal rigid structure that enabled the designers to support large propulsion engines in locations that may not otherwise be practical. The AeroTruck being developed by Russian firm Airship-GP is an example of a rigid hybrid airship. The rigid structure is designed for operating in extreme Arctic conditions and parking outdoors where snow loads and icing may be routine problems. Airship-GP also is developing a more complex variable buoyancy model of the AeroTruck.
Semi-buoyant, airplane / airship hybrids
Semi-buoyant airplane / airship hybrids are heavier-than-air, rigid, winged aircraft that carry a large helium volume to significantly reduce the weight of the aircraft and improve its load-carrying capability. Aerostatic lift provides a smaller fraction of total lift for a semi-buoyant aircraft, like a Dynalifter, than it does for a semi-buoyant, hybrid airship.
A semi-buoyant airplane / airship hybrids behaves much like a conventional aircraft in the air and on the ground, and is less affected by wind gusts and changing wind direction on the ground than a hybrid airship.
The semi-buoyant airplane / airship hybrids has some flexibility for loading and discharging cargo without having to be immediately concerned about exchanging ballast, except in windy conditions.
The Aereon Corporation’s Dynairship and the Ohio Airships Dynalifter are examples of semi-buoyant airplane / airship hybrids.
Semi-buoyant, helicopter / airship hybrids
There have been many different designs of helicopter / airship hybrids, including helistats, Dynastats and rotostats. Typically, the airship part of the hybrid craft carries the weight of the craft itself and helicopter rotors deployed in some manner around the airship work in concert to propel the craft and lift and deliver heavy payloads without the need for an exchange of ballast.
The Piasecki PA-97-34J and the Boeing / Skyhook International SkyHook JLH-40 are examples of helistats.
5.4 Stratospheric airships / High Altitude Platform Stations (HAPS)
Stratospheric airships are designed to operate at very high-altitudes, well above the jet stream and in a region of relatively low prevailing winds typically found at altitudes of 60,000 to 75,000 feet (11.4 to 14.2 miles / 18.3 to 22.9 km). This is a harsh environment where airship materials are exposed to the damaging effects of ultraviolet radiation and corrosive ozone. These airships are designed as unmanned vehicles.
Applications for stratospheric airships include military intelligence, surveillance and reconnaissance (ISR) missions, civil environmental monitoring / resource management missions, military / civil telecommunications / data relay functions, and research missions such as high-altitude astronomy. All of these can be long term missions that can last weeks, months or even years.
Typically, the stratospheric airship will operate as a “pseudo-satellite” from an assigned geo-stationary position. Station keeping 24/7 is a unique challenge. Using a hybrid electric power system, these airships can be solar-powered during the day and then operate from an energy storage source (i.e., a battery or regenerative fuel cell) at night. Some propulsion systems, such as propellers that work well at lower altitudes, may have difficulty providing the needed propulsion for station keeping or transit in the very low atmospheric pressure at operating altitude.
The DARPA / Lockheed Martin ISIS airship and the Sceye Inc. high-altitude platform are two examples of stratospheric airships.
5.5 Personal gas airships
Personal airships include a range of small LTA craft, from ultra-light, single seat recreational airships (ULM Class 5) to larger airships with a passenger capacity comparable to a personal automobile. Personal airships typically are conventional non-rigid or semi-rigid airships. They may be powered by various means, including petrol engine, electric motor, or even human-powered.
The French firm Airstar has built and flown several ultra-light airships, such as the all-electric Electroplume 250. Bryan Allen’s White Dwarf is an example of a pedal-powered personal airship.
5.6 Thermal (hot air) airships
Thermal airships use hot air as the lifting gas in place of helium or hydrogen. A given volume of hot air can lift only about one-third as much as the same volume of helium. Therefore, the gas envelope on a thermal airship is proportionally larger than it would be on a comparable airship using helium as the lifting gas.
The non-rigid GEFA-Flug four-seat AS-105GD/4 and six-seat AS-105GD/6, and the semi-rigid, two-seat Skyacht Personal Blimp are examples of current thermal airships that use propane burners to produce the hot air for lift. Pitch can be controlled with fore and aft burners. There are no ballonets.
Advanced concepts for solar-powered thermal airships are described in Modern Airships – Part 3.
5.7 Hybrid rocket / balloon (Rockoon) airships
The term “Rockoon” has been used to refer to a ground-launched, high-altitude balloon that carries a small sounding rocket aloft to be launched in the stratosphere, perhaps 15 to 20 miles (24 to 32 km) above the ground. Starting the rocket’s powered flight at high-altitude enables it to reach a much higher altitude than from a conventional ground launch.
Airship designers Michael Walden (LTAS / Walden Aerospace) and John Powell (JP Aerospace) have applied the rocket / balloon hybrid concept more broadly to produce several diverse design concepts for airships capable of operating in the stratosphere, in near-space, and all the way to Earth orbit.
For more than a decade, JP Aerospace has been developing electric / chemical MHD (magnetohydrodynamic) hybrid plasma engines for use in their planned Trans-atmospheric and Orbital Ascender airships.
5.8 Electro-kinetically (EK) propelled airships
EK propulsion uses electrostatic and/or electromagnetic fields to generate thrust, typically a rather low thrust with currently available hardware. In principle, EK propulsion could be used in place of conventional propulsion means, such as propellers and turbine engines, particularly on airships that operate in the stratosphere.
EK propulsion has been demonstrated experimentally with small, neutrally-buoyant airships, such as Michael Walden’s (LTAS / Walden Aerospace) XEM-1 rigid, hybrid EK drive demonstrator that first flew in 1974, and the graceful, non-rigid b-IONIC Airfish that was developed and flown in 2005 by the German firm Festo.
5.9 LTA drones
LTA drones are uncrewed airships that may be flown by remote control or by onboard control systems with varying degrees of autonomy. Such drones are being developed worldwide. Many LTA drones are small, conventional, elliptical or cylindrical hull airships. However, other designs, including twin-hull, spherical, lenticular and inflated delta wing have been developed and flown. Many are all-electric, and some have a photovoltaic solar array to help increase their range and operational flexibility.
Two examples of modern, autonomous, all-electric LTA drones are the Cloudline cargo drone developed in South Africa and being operationally tested since mid-2023, and Kelluu’s persistent aerial monitoring drone developed and being tested in Finland, along with an information management infrastructure for rapidly delivering processed data to clients.
5.10 Unpowered aerostats
Unpowered aerostats include tethered and free-flying balloons used in a wide variety of applications. These vehicles are not “airships.”
Tethered aerostats (kite balloons)
Many firms offer tethered aerostats for missions such as persistent surveillance and environmental monitoring, with instruments carried on the aerostat to an operating altitudes ranging from of several hundreds to several thousands of meters. The tether may be a simple steel or composite material cable (i.e., Kevlar), or it may be a powered tether that delivers electrical power to aerostat and payload systems and establishes a secure fiber optic data link between the aerostat and its ground station.
Examples are the T-C350 from the French firm A-NSE and the medium volume tethered aerostat from the Israeli firm Atlas LTA Advanced Technology.
Tethered manned aerostats
Tethered manned aerostats commonly are used in two application, as tourist sightseeing balloons and as parachute training balloons. Both applications require flying at relatively low altitude (305 m / 1,000 ft) with up to 30 tourist passengers or 8 – 10 parachute trainees. Spherical balloons are common for tourist flights. The latest Lindstrand manned aerostat has a more aerodynamic shape, like many unmanned tethered aerostats, and is able to operate in stronger wind conditions than a spherical manned aerostat.
Tethered LTA wind turbines
Tethered buoyant wind turbines operate at altitudes of hundreds to thousands of feet above the ground, where stronger prevailing winds offer more energy for harvesting than at ground level. These tethered aerostats (kite balloons) carry one or more compact, wind-driven electric power generating systems that deliver power via the tether to a substation on the ground, and then onward to a regional electrical grid.
Two examples that have been tried, but not (yet) commercialized, are the Altaeros Energies BAT and the Magenn Air Rotor System (MARS).
New, but untried airborne wind turbine systems are being developed in 2023 by Aeerstatica Energy Airships and by AirbineTM Renewable Energy Systems (ARES).
Tethered heavy lifter balloons
Another tethered aerostat application is as a heavy load lifter. In this application, the aerostat may be tethered at a fixed site to function as an heavy lift crane, replacing a conventional construction crane. The tethered aerostat may be designed for a mobile application, lifting a payload and being towed to a delivery site by a vehicle on the ground, a helicopter or by some other means.
Examples are the German CargoLifter AG CL75-AC Air Crane, which flew in 2002, and AirBarge designed by the successor firm, CL Cargolifter GmbH and Co KGaA.
Some aerostats are designed to operate on a tether and, on command, detach and continue the mission as a free-flying airship. This hybrid vehicle can operate on station for a long period of time as an tethered aerostat until something of interest is detected. Then the vehicle detaches and flies away to provide a closeup investigation at the point of interest.
Examples are the Sanswire / WSGI Argus One Hybrid aerostat / UAV and the Detachable Airship from a Tether (DATT) being developed by UAV Corp.
Free-flying, high-altitude balloons
Free-flying balloons can provide relatively low-cost access to the stratosphere. Zero-pressure balloons can lift large payloads (up to thousands of kilograms) to altitudes up to about 45,000 meters (147,638 ft / 28.0 miles) on missions lasting up to a week. Superpressure balloons can remain aloft much longer than zero-pressure balloons and can be deployed on missions of several months, but with smaller payloads. Several firms offer stratospheric assess with free-flying balloons, including Airstar Aerospace, Aerostar/TCOM, Zero 2 Infinity and JP Aerospace.
Free-flying, manned, high-altitude balloons
There are many firms developing pressurized passenger capsules to carry “space tourists” to altitudes up to about 40 km (25 miles) under very large stratospheric balloons. These flights will include a couple of hours to view the Earth from maximum altitude. After initial descent under the balloon, most of the capsules return to Earth under a parachute or parafoil with a landing on the ground or in the sea. The balloon typically is not recovered. Full-scale system test flights are expected to begin in 2024, with initial passenger flights by 2025.
6. How does an airship pick up and deliver a heavy load?
The term “load exchange” refers to the pickup and delivery of cargo by an airship, with or without an exchange of external ballast to compensate for the mass of cargo being moved on or off the airship. This isn’t a simple problem to solve.
The problem of buoyancy control
In Jeanne Marie Laskas’ article, Igor Pasternak, CEO of airship manufacturer Worldwide Aeros Corp. (Aeros), commented on the common problem facing all airships when a heavy load is delivered:
“The biggest challenge in using lighter-than-air technology to lift hundreds of tons of cargo is not with the lifting itself—the larger the envelope of gas, the more you can lift—but with what occurs after you let the stuff go. ‘When I drop the cargo, what happens to the airship?’ Pasternak said. ‘It’s flying to the moon.’ An airship must take on ballast to compensate for the lost weight of the unloaded cargo, or a ground crew must hold it down with ropes.”
Among the many current designers and manufacturers of large airships, the matter of maintaining the airship’s net buoyancy within certain limits while loading and unloading cargo and passengers is handled in several different ways depending on the type of airship involved. Some load exchange solutions require ground infrastructure at fixed bases and/or temporary field sites for external ballast handling, while others require no external ballasting infrastructure and instead use systems aboard the airship to adjust buoyancy to match current needs or provide vectored thrust (or suction) to temporarily counteract the excess buoyancy. The solution chosen for managing airship buoyancy during a load exchange strongly influences how an airship can be operationally employed and where it can pickup and deliver its payload.
Additional problems for airborne load exchanges
Several current designers and manufacturers of large airships report that their airships will have the ability to conduct airborne load exchanges of cargo from a hovering airship. Jeremy Fitton, the Director of SkyLifter, Ltd., described the key issues affecting a precision load exchange executed by a hovering airship as follows:
“The buoyancy management element of (an airborne) load-exchange is not the main control problem for airships. Keeping the aircraft in a geo-stationary position – in relation to the payload on the ground – is the main problem, of which buoyancy is a component.”
The matters of precisely maintaining the airship’s geo-stationary position throughout an airborne load exchange and controlling the heading of the airship and the suspended load are handled in different ways depending on the type of airship involved. The time required to accomplish the airborne load exchange can be many minutes or much longer, depending on the weight of the cargo being picked up or delivered and the time it takes for the airship to adjust its buoyancy for its new loaded or unloaded condition. Most of the airships offering an airborne load exchange capability are asymmetrical (i.e., conventional “cigar shaped” or hybrid aerobody-shaped) and must point their nose into the wind during an airborne load exchange. Their asymmetrical shape makes these airships vulnerable to wind shifts during the load exchange. The changing cross-sectional area exposed to the wind complicates the matter of maintaining a precise geo-position with an array of vectoring thrusters.
During such a delivery in variable winds, even with precise geo-positioning over the destination, the variable wind direction may require the hovering airship to change its heading slightly to point into the wind. This can create a significant hazard on the ground, especially when long items, such as a wind turbine blade or long pipe segment are being delivered. For example, the longest wind turbine blade currently in production is the GE Haliade-X intended for off-shore wind turbine installations. This one-piece blade is 107 meter (351 ft) long. A two degree change in airship heading could sweep the long end of the blade more than three meters (10 feet), which could be hazardous to people and structures on the ground.
Regulatory requirements pertaining to load exchanges
The German / Netherlands “Transport Airship Requirements” (TAR), includes the following requirement for load exchanges in TAR 80, “Loading / Unloading”:
(c) During any cargo exchange…the airship must be capable of achieving a safe free flight condition within a time period short enough to recover from a potentially hazardous condition.”
Similar requirements exist in the EASA proposed Special Conditions published in February 2021, in SC GAS.2125, “Loading / Unloading.”
These requirements will be a particular challenge for airships designed to execute an airborne load exchange from a hovering airship.
The CargoLifter approach to an airborne load exchange
One early approach for delivering a load from a hovering airship was developed for the CargoLifter CL160. As described on the Aviation Technology website (https://www.aerospace-technology.com/projects/cargolifter/), the CL160 would have performed an in-flight delivery of cargo as follows:
“The airship hovers at about 100 m above the ground and a special loading frame, which is fixed during flight to the keel of the airship, is then rigged with four cable winches to the ground, a procedure which is to assure that the airship’s lifting gear stays exactly above the desired position. Ballast water is then pumped into tanks on the frame and the payload can be unloaded. The anchor lines are released and the frame is pulled back into the payload bay of the airship.”
In a 2002 test using the heavy-lift CargoLifter CL75 aerostat as an airship surrogate, a 55 metric ton German mine-clearing tank was loaded, lifted and discharged from the loading frame as water ballast was unloaded and later reloaded in approximately the same time it took to secure the tank in the carriage (several minutes). In this test, the 55 metric tons cargo was exchanged with about 55 cubic meters (1,766 cubic feet, 14,530 US gallons) of water ballast.
The SkyLifter approach to an airborne load exchange
One airship design, the SkyLifter, addresses the airborne load exchange issues with a symmetrical, disc-shaped hull that presents the same effective cross-sectional area to a wind coming from any direction. With the aid of cycloidal propellers, his airship is designed to move equally well in any direction (omni-directional), simplifying airship controls in changing wind conditions, and likely giving the SkyLifter an advantage over other designs in maintaining a precise geolocation above a site while conducting an airborne load exchange without the need for the system of ground tethers used by the CL160
Some of the advanced airship concepts being developed, especially for future heavy-lift cargo carriers, will result in extremely large air vehicles on a scale not seen since the heyday of the giant zeppelins in the 1930s. Consider the following semi-rigid hybrid airships shown to scale with contemporary US Air Force fixed-wing cargo aircraft.
Size comparison for hybrid airships sized for various lift applications. Source: DoD 2012
8. Graphic tables
The airships and aerostats reviewed in Modern Airships – Part 1 are summarized in the following set of graphic tables that are organized into the airship type categories listed below:
Within each category, each page of the table is titled with the name of the airship type category and is numbered (P1.x), where P1 = Modern Airships – Part 1 and x = the sequential number of the page in that category. For example, “Conventional, rigid airships (P1.2)” is the page title for the second page in the “Conventional, rigid airships” category in Part 1. There also are conventional, rigid airships addressed in Modern Airships – Part 2. Within a category, the airships are listed in the graphic tables in approximate chronological order.
Links to the individual Part 1 articles on these airships are provided in Section 10. Some individual articles cover more than one particular airship. Have fun exploring!
9. Assessment of near-term LTA market prospects
Among the new airships described in Part 1, the following advanced airship seems to be the best candidate for achieving type certification in the next five years:
LTA Research and Exploration (USA): Pathfinder 1 rigid airship, which is expected to make its first flight in 2024. The program appears to be well funded.
The following airship manufacturers in Part 1 have advanced designs and they seem to be ready to manufacture a first commercial prototype if they can arrange adequate funding:
AT2 Aerospace (USA): Their Z1 hybrid airship formerly was known as the Lockheed Martin LMH-1. In May 2023, Lockheed Martin exited the hybrid airship business without completing type certification and transitioned that business, including intellectual property and related assets, to the newly formed, commercial company AT2 Aerospace. In June, Straightline Aviation (a former LMH-1 customer) signed a Letter of Intent with AT2 Aerospace, signaling commercial support for the Z1 hybrid airship.
Aeros (USA): It seems that Aeros has been ready for more than a decade to begin type certification and manufacture a prototype of their Aeroscraft ML866 / Aeroscraft Gen 2 variable buoyancy / fixed volume airship. The firm has reported successful subsystem tests.
Recent changes in European aviation regulations reduce some of the regulatory uncertainty for advanced airship type certification in the EU. The US FAA has not yet published comparable guidance for advanced airships, resulting in continuing regulatory uncertainty in the USA.
The promising airships in Part 1, as listed above, will be competing in the worldwide airship market with candidates identified in Modern Airships – Part 2, which potentially could enter the market in the same time frame. Among the airships described in Part 2, the following advanced airship seems to be the best candidate for achieving type certification in the next five years:
Flying Whales (France): The LCA60T rigid cargo airship was significantly redesigned in 2021, which resulted in a considerable schedule delay. In March 2023, Flying Whales reported that they expected to complete construction and flight testing of the first production prototype in the 2024 – 2025 timeframe, followed by EASA certification and start of industrial production in 2026. The project appears to be well funded from diverse international sources in France, Canada, China and Morocco. Full-scale production facilities are planned in France, China and Canada and commercial airship operating infrastructure is being planned.
Hybrid Air Vehicles (UK): The Airlander 10 commercial passenger / cargo hybrid airship is being developed by HAV based on their experience with the Airlander 10 prototype, which flew from 2016 to 2017. In 2022, Valencia, Spain-based Air Nostrum, which operates regional flights, ordered 10 Airlander 10 aircraft, with delivery scheduled for 2026. Also in 2022, Highlands and Islands Airport (HIAL) sponsored a study for introducing the Airlander 10 in Scotland. In April 2023, the regional UK government of South Yorkshire concluded a financial agreement that is expected to lead to the Airlander 10 being manufactured in Doncaster, in the north of England. Things are moving in the right direction. However, FutureFlight reported that “the plan cannot proceed unless HAV secures a strategic investor. It needs at least £100 million to begin construction.”
The following airship manufacturers in Part 2 have advanced designs and they seem to be ready to manufacture a first prototype if they can arrange funding:
Aerovehicles (USA / Argentina): They claim their AV-10 non-rigid, multi-mission blimp can carry a 10 metric ton payload and be type certified within existing regulations for blimps. This should provide a lower-risk route to market for an airship with an operational capability that does not exist today.
Atlas LTA Advanced Technology (Israel): After acquiring the Russian firm Augur RosAeroSystems in 2018, Atlas is continuing to develop the ATLANT variable buoyancy, fixed volume heavy lift airship. They also are developing a new family of non-rigid Atlas-6 and -11 blimps and unmanned variants. However, the development plans and schedules have not yet been made public.
BASI (Canada): The firm has a well-developed design in the MB-30T and a fixed-base operating infrastructure design that seems to be well suited for their primary market in the Arctic.
Euro Airship (France): The firm reports having production-ready plans for their rigid airship designs. In June 2023, Euro Airship announced plans to build and fly a large rigid airship known as Solar Airship One around the world in 2026.
Millennium Airship (USA & Canada): The firm has well developed designs for their SF20T and SF50T SkyFreighters, has identified its industrial team for manufacturing, and has a business arrangement with SkyFreighter Canada, Ltd., which would become a future operator of SkyFreighter airships in Canada. In addition, their development plan defines the work needed to build and certify a prototype and a larger production airship.
The 2020s will be an exciting time for the airship industry. We’ll finally get to see if the availability of several different heavy-lift airships with commercial type certificates will be enough to open a new era in airship transportation. Aviation regulatory agencies need to help reduce investment risk by reducing regulatory uncertainty and putting in place an adequate regulatory framework for the wide variety of advanced airships being developed. Customers with business cases for airship applications need to step up, place firm orders, and then begin the pioneering task of employing their airships and building a worldwide airship transportation network with associated ground infrastructure. This will require consistent investment over the next decade or more before a basic worldwide airship transportation network is in place to support the significant use of commercial airships in cargo and passenger transportation and other applications. Perhaps then we’ll start seeing the benefits of airships as a lower environmental impact mode of transportation and a realistic alternative to fixed-wing aircraft, seaborne cargo vessels and heavy, long-haul trucks.
10. Links to the individual articles
The following links will take you to the individual Modern Airships – Part 1 articles. The organization of the following list matches the graphic table.
Note that several of these articles address more than one airship design from the same manufacturer / designer and they may be in different categories (i.e., Airship Industries, Ohio Airships, Walden Aerospace). These designs are listed separately in the above graphic tables and in the following index. The links listed below will take you to the correct article.
“Modern Airships” is a three-part document that contains an overview of modern airship technology in Part 1 and links in Parts 1, 2 and 3 to more than 285 individual articles on historic and advanced airship designs. This is Part 3. Here are the links to the other two parts:
To help you navigate the large volume of material in these three documents, please refer to following indexes. The first index simply lists the article titles in alphabetic order within each Part.
Parts 1 & 2 address similar types of airships and unpowered aerostats. The following airship type index enables you to see all of the airships and aerostats addressed in Parts 1 & 2, grouped by type, with direct links to the relevant articles.
The airships described in Part 3 are relatively exotic concepts in comparison to the more utilitarian and heavy-lift airships that dominate Parts 1 and 2. As shown in the following index, the airships in Part 3 are organized by function rather than airship type, which sometimes is difficult to determine with the information available.
Modern Airships – Part 3 begins with a graphic table identifying the airship concepts addressed in this part, and concludes by providing links to more than 50 individual articles on these airship concepts. A downloadable pdf copy of Part 3 is available here:
If you have any comments or wish to identify errors in these documents, please send me an e-mail to: [email protected].
I hope you’ll find the Modern Airships series to be informative, useful, and different from any other single document on this subject.
Best regards,
Peter Lobner
6 November 2024
Record of revisions to Part 3
Original Modern Airships post, 26 August 2016: addressed 14 airships in a single post.
Expanded the Modern Airships post and split it into three parts, 18 August 2019: Part 3 included 32 linked articles.
Part 3, Revision 1, 21 December 2020: Added 1 new article on Walden Aerospace. Part 3 now had 33 articles
Part 3, Revision 2, 8 February 2022: Added 14 new articles, moved over and updated the Halo article from Part 1 and updated 12 of the original articles. A detailed summary of changes incorporated in Part 3, Rev. 2 is listed here. Part 3 now had 48 articles.
Part 3, Revision 3, 18 March 2022: Added 1 new article, reorganized the graphic table and updated 22 of the original articles. With this revision, all Part 3 linked articles have been updated in February or March 2022. A detailed summary of changes incorporated in Part 3, Rev. 3 is listed here. Part 3 now has 49 articles.
Part 3, Revision 4, 18 March 2024: Added 3 new articles and updated 1 of the original articles. Updated graphics tables. Added indexes for Parts 1, 2 & 3. A detailed summary of changes incorporated in Part 3, Rev. 4 is listed here. Part 3 now has 52 articles.
Part 3, changes since Rev. 4 (18 March 2024)
New articles:
Lazzarini Design Studio – Colossea
Leoni Design Workshop – Air Cube
Updated articles:
None yet
2. Graphic tables
The airship design concepts reviewed in Modern Airships – Part 3 are summarized in the following set of graphic tables. I’ve grouped these airship concepts based on their applications rather than on their design / type (as in Parts 1 and 2) because those details sometimes are difficult to determine when few graphics and limited descriptions are available.
Cargo & multi-purpose airships
Mass transportation airships
Flying hotel airships
Touring airships
Flying yacht airships
Autonomous special purpose airships
Personal airships
Thermal (hot air) airships
Biomimetic airships
Rocket / airship (Rockoon) hybrids
Combat airships
Within each category, each page of the table is titled with the name of the category and is numbered (P3.x), where P3 = Modern Airships – Part 3 and x = the sequential number of the page in that category. For example, “Flying hotel airships (P3.2)” is the page title for the second page in the “Flying hotel airships” category in Part 3. Within each category, the airships are listed in an approximate chronological order.
Except for a few sub-scale models, none of the airship concepts in Part 3 have flown. A few of these airships look good as concepts, but may be impossible to build. Nonetheless, all of these relatively exotic concepts point toward an airship future that will benefit from the great creativity expressed by these designers.
Links to the individual Part 3 articles on these airships are provided in Section 3.
3. Links to the individual articles
The following links will take you to the individual articles.
Note that a few of these articles address more than one airship design concept from the same designer and these airship concepts may be in different categories (i.e., Avalon Airships, Bauhaus Luftfahrt, Walden Aerospace). Each design concept is listed separately in the above graphic tables and in the following index. The links listed below will take you to the correct article.
Peter Lobner, updated 6 November 2024 (post-Rev. 6)
1. Introduction
Modern Airships is a three-part document that contains an overview of modern airship technology in Part 1 and links in Parts 1, 2 and 3 to more than 285 individual articles on historic and advanced airship and aerostat designs. This is Part 2. Here are the links to the other two parts:
To help you navigate the large volume of material in these three documents, please refer to following indexes. The first index simply lists the article titles in alphabetic order within each Part.
Parts 1 & 2 address similar types of airships and unpowered aerostats. The following airship type index enables you to see all of the airships and aerostats addressed in Parts 1 & 2, grouped by type, with direct links to the relevant articles.
The airships described in Part 3 are relatively exotic concepts in comparison to the more utilitarian and heavy-lift airships that dominate Parts 1 and 2. As shown in the following index, the airships in Part 3 are organized by function rather than airship type, which sometimes is difficult to determine with the information available.
Modern Airships – Part 2 begins with a set of graphic tables that identify the airships addressed in this part, and concludes by providing links to more than 120 individual articles on those airships. A downloadable pdf copy of Part 2 (Rev. 6) is available here:
Each of the linked articles can be individually downloaded.
If you have any comments or wish to identify errors in these documents, please send me an e-mail to: [email protected].
I hope you’ll find the Modern Airships series to be informative, useful, and different from any other single document on this subject.
Best regards,
Peter Lobner
6 November 2024
Record of revisions to Part 2
Original Modern Airships post, 26 August 2016: addressed 14 airships in a single post.
Expanded the Modern Airships post and split it into three parts, 18 August 2019: Part 2 included 25 articles
Part 2, Revision 1, 21 December 2020: Added 2 new articles on Walden Aerospace. Part 2 now had 27 articles
Part 2, Revision 2, 3 April 2021: Added 35 new articles, split the original variable buoyancy propulsion article into three articles, and updated all of the original articles. Also updated and reformatted the summary graphic table. Part 2 now had 64 articles.
Part 2, Revision 3, 9 September 2021: Updated 7 articles. Added category for “thermal (hot air) airships” and added pages for them in the summary graphic table. Part 2 still had 64 articles.
Part 2, Revision 4, 11 February 2022: Added 26 new articles, expanded the graphic tables and updated 12 existing articles. A detailed summary of changes incorporated in Part 2, Rev 4 is listed here. Part 2 now had 90 articles.
Part 2, Revision 5, 10 March 2022: Added 1 new article, split rigid & semi-rigid airships in the graphic tables, and updated 52 existing articles. With this revision, all Part 2 linked articles have been updated in February or March 2022. A detailed summary of changes incorporated in Part 2, Rev 5 is listed here. Part 2 now has 91 articles.
Part 2, Revision 6, 17 March 2024: This revision includes a major reorganization of Parts 1 & 2 to better aggregate airships and unpowered aerostats by type, with a corresponding reorganization of the graphic tables. Over the past two years, 28 new articles were added to Part 2 and 27 articles were updated. In the final changes for Rev. 6, several articles were moved between Parts 1 & 2. A detailed summary of changes incorporated in Part 2, Rev 6 is listed here. Part 2 now has 117 articles.
Part 2, changes since Rev. 6 (17 March 2024)
New articles:
Altaeros Energies Inc. – Buoyant Air Turbine (BAT) – 31 October 2024
Beijing SAWES Energy Technology Co. – Buoyant Air Turbine (BAT) – 31 October 2024
Magenn Power Inc. – Magenn Air Rotor System (MARS) – 31 October 2024
China’s Aerospace Research Institute – Jimu No. 1, Type III, high-altitude tethered aerostat – 13 September 2024
LTA Aerostructures (LTAA) – rigid airships – 6 November 2024
2. Graphic tables
The airships reviewed in Modern Airships – Part 2 are summarized in the following set of graphic tables that are organized into the categories listed below:
Within each category, each page of the table is titled with the name of the airship type category and is numbered (P2.x), where P2 = Modern Airships – Part 2 and x = the sequential number of the page in that category. For example, “Conventional, rigid airships (P2.2)” is the page title for the second page in the “Conventional, rigid airships” category in Part 2. There also are conventional, rigid airships addressed in Modern Airships – Part 1. Within a category, the airships are listed in the graphic tables in approximate chronological order.
Links to the individual Part 2 articles on these airships are provided in Section 10. Some individual articles cover more than one particular airship. Have fun exploring!
3. Assessment of near-term LTA market prospects
Among the airships described in Part 2, the following advanced airship seems to be the best candidate for achieving type certification in the next five years:
Flying Whales (France): The LCA60T rigid cargo airship was significantly redesigned in 2021, which resulted in a considerable schedule delay. In March 2023, Flying Whales reported that they expected to complete construction and flight testing of the first production prototype in the 2024 – 2025 timeframe, followed by EASA certification and start of industrial production in 2026. The project appears to be well funded from diverse international sources in France, Canada, China and Morocco. Full-scale production facilities are planned in France, China and Canada and commercial airship operating infrastructure is being planned.
Hybrid Air Vehicles (UK): The Airlander 10 commercial passenger / cargo hybrid airship is being developed by HAV based on their experience with the Airlander 10 prototype, which flew from 2016 to 2017. In 2022, Valencia, Spain-based Air Nostrum, which operates regional flights, ordered 10 Airlander 10 aircraft, with delivery scheduled for 2026. Also in 2022, Highlands and Islands Airport (HIAL) sponsored a study for introducing the Airlander 10 in Scotland. In April 2023, the regional UK government of South Yorkshire concluded a financial agreement that is expected to lead to the Airlander 10 being manufactured in Doncaster, in the north of England. Things are moving in the right direction. In March 2023, HAV reported that manufacturing of the first production airship will start in 2023, followed by first flight in 2025 and service entry in 2027.
The following airship manufacturers in Part 2 have advanced designs and they seem to be ready to manufacture a first prototype if they can arrange funding:
Aerovehicles (USA / Argentina): They claim their AV-10 non-rigid, multi-mission blimp can carry a 10 metric ton payload and be type certified within existing regulations for blimps. This should provide a lower-risk route to market for an airship with an operational capability that does not exist today.
Atlas LTA Advanced Technology (Israel): After acquiring the Russian firm Augur RosAeroSystems in 2018, Atlas is continuing to develop the ATLANT variable buoyancy, fixed volume heavy lift airship. They also are developing a new family of non-rigid Atlas-6 and -11 blimps and unmanned variants. However, the development plans and schedules have not yet been made public.
BASI (Canada): The firm has a well-developed design in the MB-30T and a fixed-base operating infrastructure design that seems to be well suited for their primary market in the Arctic.
Euro Airship (France): The firm reports having production-ready plans for their rigid airship designs. In June 2023, Euro Airship announced plans to build and fly a large rigid airship known as Solar Airship One around the world in 2026.
Millennium Airship (USA & Canada): The firm has well developed designs for their SF20T and SF50T SkyFreighters, has identified its industrial team for manufacturing, and has a business arrangement with SkyFreighter Canada, Ltd., which would become a future operator of SkyFreighter airships in Canada. In addition, their development plan defines the work needed to build and certify a prototype and a larger production airship.
The promising airships in Part 2, listed above, will be competing in the worldwide airship market with candidates identified in Modern Airships – Part 1, which potentially could enter the market in the same time frame. Among the new airships described in Part 1, the following advanced airship seems to be the best candidates for achieving type certification in the next five years:
LTA Research and Exploration (USA): Pathfinder 1 rigid airship, which is expected to make its first flight in early 2024. The program appears to be well funded.
The following airship manufacturers in Part 1 have advanced designs and they seem to be ready to manufacture a first commercial prototype if they can arrange adequate funding:
AT2 Aerospace (USA): Their Z1 hybrid airship formerly was known as the Lockheed Martin LMH-1. In May 2023, Lockheed Martin exited the hybrid airship business without completing type certification and transitioned that business, including intellectual property and related assets, to the newly formed, commercial company AT2 Aerospace. In June, Straightline Aviation (a former LMH-1 customer) signed a Letter of Intent with AT2 Aerospace, signaling commercial support for the Z1 hybrid airship.
Aeros (USA): It seems that Aeros has been ready for more than a decade to begin type certification and manufacture a prototype of their Aeroscraft ML866 / Aeroscraft Gen 2 variable buoyancy / fixed volume airship. The firm has reported successful subsystem tests.
For decades, there have been many ambitious projects that intended to operate an airship as a pseudo-satellite, carrying a heavy payload while maintaining a geo-stationary position in the stratosphere on a long-duration mission (days, weeks, to a year or more). None were successful. This led NASA in 2014 to plan the 20-20-20 airship challenge: 20 km altitude, 20 hour flight, 20 kg payload. The challenge never occurred, but it highlighted the difficulty of developing an airship as a persistent pseudo-satellite. The most promising new stratospheric airship manufacturers identified in Part 2 are:
Sceye Inc. (USA): This small firm has built a headquarters and manufacturing facility in New Mexico. Since 2017, it has been developing a mid-size, multi-mission stratospheric airship aimed at demonstrating the ability to deliver communications services to users living in remote regions. A sub-scale vehicle first flew in 2017. Short-duration flights of a prototype stratospheric airship have been conducted since 2021.
Thales Alenia Space (France): The firm is developing the multi-mission Stratobus. Their latest round of funding from France’s defense procurement agency called for a full-scale, autonomous Stratobus demonstrator airship to fly by the end of 2023, five years later than another demonstrator that was ordered in the original 2016 Stratobus contract, but not built. Thales Alenia Space missed the end of 2023 target and an updated schedule has not yet been announced.
China remains an outlier after the 2015 flight of the Yuanmeng stratospheric airship developed by Beijing Aerospace Technology Co. & BeiHang. The current status of the Chinese stratospheric airship development program is not described in public documents.
Among the many smaller airships identified in Part 2, the following manufacturers could have their airships flying by the mid 2020s if adequate funding becomes available.
Dirisolar (France): The firm has a well-developed design for their five passenger DS 1500, which is intended initially for local air tourism, but can be configured for other missions. When funding becomes available, it seems that they’re ready to go.
A-NSE (France): The firm offers a range of aerostat and small airships, several with a novel tri-lobe, variable volume hull design. Such aerostats are operational now, and a manned tri-lobe airship could be flying later in the 2020s.
There has been a proliferation of small LTA drone blimps and other small LTA drone vehicles. Some were developed initially for military surveillance applications, but all are configurable and could be deployed in a range of applications. Some enterprising LTA drone developers also are developing value-adding applications and are offering information services, rather than simply selling a drone to be operated by a customer.
The 2020s will be an exciting time for the airship industry. We’ll finally get to see if the availability of several different heavy-lift airships with commercial type certificates will be enough to open a new era in airship transportation. Aviation regulatory agencies need to help reduce investment risk by reducing regulatory uncertainty and putting in place an adequate regulatory framework for the wide variety of advanced airships being developed. Customers with business cases for airship applications need to step up, place firm orders, and then begin the pioneering task of employing their airships and building a worldwide airship transportation network with associated ground infrastructure. This will require consistent investment over the next decade or more before a basic worldwide airship transportation network is in place to support the significant use of commercial airships in cargo and passenger transportation and other applications. Perhaps then we’ll start seeing the benefits of airships as a lower environmental impact mode of transportation and a realistic alternative to fixed-wing aircraft, seaborne cargo vessels and heavy, long-haul trucks.
4. Links to the individual articles
The following links will take you to the individual articles that address all of the airships identified in the preceding graphic table.
Note that a few of these articles address more than one airship design from the same manufacturer / designer and they may be in different categories (i.e., Augur RosAeroSystems, Atlas LTA Advanced Technology). These designs are listed separately in the above graphic tables and the following index. The links listed below will take you to the same article.
