Category Archives: Commercial aviation

Paul Allen’s Stratolaunch Aircraft Makes its First Flight, but With an Uncertain Business Plan

Background

The firm Orbital ATK (formerly Orbital Sciences Corporation) was the first to develop a commercial, air-launched rocket capable of placing payloads into Earth orbit.  Initial tests of their modest-size Pegasus launch vehicle were made in 1990 from the NASA B-52 that previously had been used as the “mothership” for the X-15 experimental manned space plane and many other experimental vehicles.

Since 1994, Orbital ATK has been using a specially modified civilian Lockheed L-1011 TriStar, a former airliner renamed Stargazer, as a mothership to carry a Pegasus launch vehicle to high altitude, where the rocket is released to fly a variety of missions, including carrying satellites into orbit.  With a Pegasus XL  as its payload (launch vehicle + satellite), Stargazer is lifting up to 23,130 kg (50,990 pounds) to a launch point at an altitude of about 12.2 km (40,000 feet).

Orbital ATK’s Pegasus XL rocket released from Stargazer.  
Source: NASA / http://mediaarchive.ksc.nasa.gov

You can watch a 2015 video celebrating 25 years of Orbital ATK’s Pegasus air-launched rocket at the following link: https://www.youtube.com/watch?v=0L47cpXTzQU

Paul Allen’s firm Stratolaunch Systems Corporation (https://www.stratolaunch.com) was founded in 2011 to take this air-launch concept to a new level with their giant, twin-fuselage, six-engine Stratolaunch carrier aircraft.  The aircraft has a wingspan of 385 feet (117 m), which is the greatest of any aircraft ever built, a length of 238 feet (72.5 m), and a height of 50 feet (15.2 m) to the top of the vertical tails. The empty weight of the aircraft is about 500,000 pounds (226,796 kg).  It is designed for a maximum takeoff weight of 1,300,000 pounds (589,670 kg), leaving about 550,000 pounds (249,486 kg) for its payload and the balance for fuel and crew.  It will be able to carry multiple launch vehicles on a single mission to a launch point at an altitude of about 35,000 feet (10,700 m).  A mission profile for the Stratolaunch aircraft is shown in the following diagram.

Typical air-launch mission profile. Source: Stratolaunch Systems

Stratolaunch rollout – 2017

Built by Scaled Composites, the Stratolaunch aircraft was unveiled on 31 May 2017 when it was rolled out at the Mojave Air and Space Port in Mojave, CA.  Following is a series of photos from Stratolaunch Systems showing the rollout.

Stratolaunch ground tests – 2017 to 2019

Ground testing of the aircraft systems started after rollout. By mid-September 2017, the first phase of engine testing was completed, with all six Pratt & Whitney PW4000 turbofan engines operating for the first time.  The first low-speed ground tests conducted in December 2017 reached a modest speed of 25 knot (46 kph).  By January 2019, the high-speed taxi tests had reached a speed of about 119 knots (220 kph) with the nose wheel was off the runway, almost ready for lift off. Following is a series of photos from Stratolaunch Systems showing the taxi tests.

Stratolaunch first flight

The Stratolaunch aircraft, named Roc, made an unannounced first flight from the Mojave Air & Space Port on 13 April 2019.  The aircraft stayed aloft for 2.5 hours, reached a peak altitude of 17,000 feet (5,180 m) and a top speed of 189 mph (304 kph). Following is a series of photos from Stratolaunch Systems showing the Stratolaunch aircraft during its first flight.

Stratolaunch posted an impressive short video of the first flight, which you can view here:

Stratolaunch family of launch vehicles: ambitious plans, but subject to change

In August 2018, Stratolaunch announced its ambitious launch vehicle development plans, which included the family of launch vehicles shown in the following graphic:

  • Up to three Pegasus XL launch vehicles from Northrop Grumman Innovation Systems (formerly Orbital ATK) can be carried on a single Stratolaunch flight. Each Pegasus XL is capable of placing up to 370 kg (816 lb) into a low Earth orbit (LEO, 400 km / 249 mile circular orbit).
  • Medium Launch Vehicle (MLV) capable of placing up to 3,400 kg (7,496 lb) into LEO and intended for short satellite integration timelines, affordable launch and flexible launch profiles.  MLV was under development and first flight was planned for 2022.
  • Medium Launch Vehicle – Heavy, which uses three MLV cores in its first stage. That vehicle would be able to place 6,000 kg (13,228 lb) into LEO.  MLV-Heavy was in the early development stage.
  • A fully reusable space plane named Black Ice, initially intended for orbital cargo delivery and return, with a possible follow-on variant for transporting astronauts to and from orbit.  The space plane was a design study.

Stratolaunch was developing a 200,000 pound thrust, high-performance, liquid fuel hydrogen-oxygen rocket engine, known as the “PGA engine”, for use in their family of launch vehicles.  Additive manufacturing was being widely used to enable rapid prototyping, development and manufacturing.   Successful tests of a 100% additive manufactured major subsystem called the hydrogen preburner were conducted in November 2018.

Stratolaunch Systems planned family of launch vehicles announced in August 2018.
Source: Stratolaunch Systems

After Paul Allen’s death on 15 October 2018, the focus of Stratolaunch Corp was greatly revised. On 18 January 2019, the company announced that it was ending work on its own family of launch vehicles and the PGA rocket engine. The firm announced, “We are streamlining operations, focusing on the aircraft and our ability to support a demonstration launch of the Northrop Grumman Pegasus XL air-launch vehicle.”    

You’ll find an article describing Stratolaunch Systems’ frequently changing launch vehicle plans in an article on the SpaceNews website here:

https://spacenews.com/stratolaunch-abandons-launch-vehicle-program/

What is the future for Stratolaunch?

With only the Pegasus XL as a launch vehicle, and Northrop Grumman having their own Stargazer carrier aircraft for the Pegasus XL, the business case for the Stratolaunch aircraft has been greatly weakened.  Air launch certainly offers a great deal of flexibility for launching small satellites. However, it appears that the newest generation of small orbital launch vehicles, like Electron (Rocket Lab, New Zealand) and Prime (Orbix, UK) will be able to offer similar launch services at lower cost.  Electron is operational now, and Prime is expected to enter service in 2021.  

In a cost competitive launch services market, Stratolaunch does not seem to have an advantage with only the Pegasus XL in its launch vehicle inventory.  Hopefully, they have something else up their sleeve that will take advantage of the remarkable capabilities of the Stratolaunch carrier aircraft.

Stratolaunch’s main competition:  The Northrop Grumman Stargazer at the Mojave Air and Space Port in January 2019, available for its next Pegasus XL launch mission.  Source: Author’s photo

Airbus Delivers its 10,000th Aircraft

Airbus was founded on 18 December 1970 and delivered its first aircraft, an A300B2, to Air France on 10 May 1974. This was the world’s first twin-engine, wide body (two aisles) commercial airliner, beating Boeing’s 767, which was not introduced into commercial service until September 1982. The A300 was followed in the early 1980s by a shorter derivative, the A310, and then, later that decade, by the single-aisle A320. The A320 competed directly with the single-aisle Boeing 737 and developed into a very successful family of single-aisle commercial airliners: A318, A319, A320 and A321.

On 14 October 2016, Airbus announced the delivery of its 10,000th aircraft, which was an A350-900 destined for service with Singapore Airlines.

EVE-1236Source: Airbus

In their announcement, Airbus noted:

“The 10,000th Airbus delivery comes as the manufacturer achieves its highest level of production ever and is on track to deliver at least 650 aircraft this year from its extensive product line. These range from 100 to over 600 seats and efficiently meet every airline requirement, from high frequency short haul operations to the world’s longest intercontinental flights.”

You can read the complete Airbus press release at the following link:

http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/-9b32c4364a/

As noted previously, Airbus beat Boeing to the market for twinjet, wide-body commercial airliners, which are the dominant airliner type on international and high-density routes today. Airbus also was an early adopter of fly-by-wire flight controls and a “glass cockpit”, which they first introduced in the A320 family.

In October 2007, the ultra-large A380 entered service, taking the honors from the venerable Boeing 747 as the largest commercial airliner.   Rather than compete head-to-head with the A380, Boeing opted for stretching its 777 and developing a smaller, more advanced and more efficient, all-composite new airliner, the 787, which was introduced in airline service 2011.

Airbus countered with the A350 XWB in 2013. This is the first Airbus with fuselage and wing structures made primarily of carbon fiber composite material, similar to the Boeing 787.

The current Airbus product line comprises a total of 16 models in four aircraft families: A320 (single aisle), A330 (two aisle wide body), A350 XWB (two aisle wide body) and A380 (twin deck, two aisle wide body). The following table summarizes Airbus commercial jet orders, deliveries and operational status as of 30 November 2016.

Airbus orders* Includes all models in this family. Source: https://en.wikipedia.org/wiki/Airbus

Boeing is the primary competitor to Airbus. Boeing’s first commercial jet airliner, the 707, began commercial service Pan American World Airways on 26 October 1958. The current Boeing product line comprises five airplane families: 737 (single-aisle), 747 (twin deck, two aisle wide body), 767 (wide body, freighter only), 777 (two aisle wide body) and 787 (two aisle wide body).

The following table summarizes Boeing’s commercial jet orders, deliveries and operational status as of 30 June 2016. In that table, note that the Boeing 717 started life in 1965 as the Douglas DC-9, which in 1980 became the McDonnell-Douglas MD-80 (series) / MD-90 (series) before Boeing acquired McDonnell-Douglas in 1997. Then the latest version, the MD-95, became the Boeing 717.

Boeing commercial order status 30Jun2016

Source: https://en.wikipedia.org/wiki/Boeing_Commercial_Airplanes

Boeing’s official sales projections for 2016 are for 740 – 745 aircraft. Industry reports suggest a lower sales total is more likely because of weak worldwide sales of wide body aircraft.

Not including the earliest Boeing models (707, 720, 727) or the Douglas DC-9 derived 717, here’s how the modern competition stacks up between Airbus and Boeing.

Single-aisle twinjet:

  • 12,805 Airbus A320 family (A318, A319, A320 and A321)
  • 14,527 Boeing 737 and 757

Two-aisle twinjet:

  • 3,260 Airbus A300, A310, A330 and A350
  • 3,912 Boeing 767, 777 and 787

Twin aisle four jet heavy:

  • 696 Airbus A340 and A380
  • 1,543 Boeing 747

These simple metrics show how close the competition is between Airbus and Boeing. It will be interesting to see how these large airframe manufacturers fare in the next decade as they face more international competition, primarily at the lower end of their product range: the single-aisle twinjets. Former regional jet manufacturers Bombardier (Canada) and Embraer (Brazil) are now offering larger aircraft that can compete effectively in some markets. For example, the new Bombardier C Series is optimized for the 100 – 150 market segment. The Embraer E170/175/190/195 families offer capacities from 70 to 124 seats, and range up to 3,943 km (2,450 miles).  Other new manufacturers soon will be entering this market segment, including Russia’s Sukhoi Superjet 100 with about 108 seats, the Chinese Comac C919 with up to 168 seats, and Japan’s Mitsubishi Regional Jet with 70 – 80 seats.

At the upper end of the market, demand for four jet heavy aircraft is dwindling. Boeing is reducing the production rate of its 747-8, and some airlines are planning to not renew their leases on A380s currently in operation.

It will be interesting to watch how Airbus and Boeing respond to this increasing competition and to increasing pressure for controlling aircraft engine emissions after the Paris Agreement became effective in November 2016.

Status of Ukraine’s Giant Transport Aircraft: Antonov An-124 and An-225

Historically, the Antonov Design Bureau was responsible for the design and development of large military and civil transport aircraft for the former Soviet Union. With headquarters and production facilities in and around Kiev, this Ukrainian aircraft manufacturing and servicing firm is now known as Antonov State Company. The largest of the jet powered transport aircraft built by Antonov are the four-engine An-124 and the even larger six-engine An-225.

An-124 Ruslan (NATO name: Condor)

The An-124 made its first flight in December 1982 and entered operational service in 1986. This aircraft is a counterpart to the Lockheed C-5A, which is the largest U.S. military transport aircraft. A comparison of the basic parameters of these two aircraft is presented in the following table.

An-124 vs C-5A_AviatorjoedotnetSource: aviatorjoe.net

As you can see in this comparison, the An-124 is somewhat larger than the C-5A, which has a longer range, but at a slower maximum speed.

The An-124 currently is operated by the Russian air force and also by two commercial cargo carriers: Ukraine’s Antonov Airlines and Russia’s Volga-Dnepr Airlines. The civil An-124-100 is a commercial derivative of the military An-124. The civil version was certified in 1992, and meets all current civil standards for noise limits and avionic systems.

In their commercial cargo role, these aircraft specialize in carrying outsized and/or very heavy cargo that cannot be carried by other aircraft. These heavy-lift aircraft serve civil and military customers worldwide, including NATO and the U.S. military. I’ve seen an An-124s twice on the tarmac at North Island Naval Station in San Diego. In both cases, it arrived in the afternoon and was gone before sunrise the next day. Loading and/or unloading occurred after dark.

An-124_RA-82028_09-May-2010An-124-100. Source: Wikimedia Commons

As shown in the following photo, the An-124 can retract its nose landing gear and “kneel” to facilitate cargo loading through the raised forward door.

An-124_ramp downAn-124-100. Source: Mike Young / Wikimedia Commons

The following diagram shows the geometry and large size of the cargo hold on the An-124. The built-in cargo handling equipment includes an overhead crane system capable of lifting and moving loads up to 30 metric tons (about 66,100 pounds) within the cargo hold. As shown in the diagram below, the cargo hold is about 36.5 meters (119.7 feet) long, 6.4 meters (21 feet) wide, and the clearance from the floor to the ceiling of the cargo hold is 4.4 meters (14.4 feet). The installed crane hoists may reduce overhead clearance to 3.51 meters (11.5 feet).

An-124-diagram_tcm87-4236An-124-100 cargo hold dimensions. Source: aircharterservice.com

An-124_takeoffAn-124-100. Source: aircharterservice.com

Production of the An-124 was suspended following the Russian annexation of Crimea in 2014 and the ongoing tensions between Russia and Ukraine. In spite of repeated attempts by Ukraine to restart the An-124 production line, it appears that Antonov may not have the resources to restart An-124 production. For more information on this matter, see the 22 June 2016 article on the Defense Industry Daily website at the following link:

http://www.defenseindustrydaily.com/more-an124s-on-the-way-antonov-signs-agreement-with-key-customers-02913/?utm_source=Sailthru&utm_medium=email&utm_campaign=Military%20EBB%206-22-16&utm_term=Editorial%20-%20Military%20-%20Early%20Bird%20Brief

An-225 Mriya

The An-225 was adapted from the An-124 and significantly enlarged to serve as the carrier aircraft for the Soviet space shuttle, the Buran. The relative sizes of the An-124 and An-225 are shown in the following diagram, with a more detailed comparison in the following table.

An-124 & 225 planform comparisonAn-124 & -225 comparison. Source: Airvectors.com

An-124 & 225 comparisonAn-124 & -225 comparison. Source: aviatorjoe.net

The only An-225 ever produced made its first flight in December 1988. It is shown carrying the Buran space shuttle in the following photo.

AN-225 & BuranAn-225 carrying Buran space shuttle. Source: fcba.tumblr.com

After the collapse of the Soviet Union in 1991 and the cancellation of the Buran space program, the An-225 was mothballed for eight years until Antonov Airlines reactivated the aircraft for use as a commercial heavy-lift transport. In this role, it can carry ultra-heavy / oversize cargo weighing up to 250 metric tons (551,000 pounds).

An-225 gear downAn-225 Mriya. Source: AntonovAn-225 gear up

Surprisingly, it appears that the giant An-225 is about to enter series production. Antonov and Aerospace Industry Corporation of China (AICC) signed a deal on 30 August 2016 that will result in An-225 production in China. The first new An-225 could be produced in China as early as in 2019.

When it enters service, this new version of the An-225 will modernize and greatly expand China’s military and civil airlift capabilities. While it isn’t clear how this airlift capability will be employed, it certainly will improve China ability to deliver heavy machinery, bulk material, and many personnel anywhere in the world, including any location in and around the South China Sea that has an adequate runway.

For more information on this Ukraine – China deal, see the 31 August 2016 article by Gareth Jennings entitled, “China and Ukraine agree to restart An-225 production,” on the IHS Jane’s 360 website at the following link:

http://www.janes.com/article/63341/china-and-ukraine-agree-to-restart-an-225-production

You’ll find more general information on the An-124 and An-225 on the Airvectors website at the following link:

http://www.airvectors.net/avantgt.html

 

 

 

 

Modern Airships – Part 1

This post was updated on 18 April 2019.

Background

For more than two 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 serving remote and/or unimproved sites
  • Persistent optionally-manned surveillance platforms
  • Maritime surveillance / search and rescue
  • Disaster relief, particularly in areas not easily accessible by other means
  • Unmanned aerial vehicle (UAV) / unmanned air system (UAS) carrier
  • Commercial flying cruise liner

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 has lower environmental impact than other transportation alternatives for those regions.  This issue is described well in a 21 February 2016 article by Jeanne Marie Laskas, “Helium Dreams – A new generation of airships is born,” which is posted on The New Yorker website, along with the following very optimistic airship concept drawing, at the following link:

https://www.newyorker.com/magazine/2016/02/29/a-new-generation-of-airships-is-born

In spite of the significant interest, actual military, commercial and other customers have been slow coming to the marketplace with firm orders, the airship manufacturers have been slow in developing and delivering advanced airships that meet their customer’s needs, and funding was prematurely curtailed for several ambitious projects.  This uncertain business climate seems likely tochange by the early 2020s, when several different heavy-lift airships are expected to be certified by airworthiness authorities and ready for mass production and sale to interested customers.

Some of the advanced airship concepts being developed, especially for future heavy cargo carriers, will result in extremely large air vehicles on a scale we haven’t seen since the heyday of the giant zeppelins in the 1930s.  Consider the following hybrid airships shown to scale with contemporary fixed-wing cargo aircraft.

Size comparison for hybrid airships required for various lift applications.  Source: DoD 2012

In this post, we’ll take a look at the following advanced airship designs and concepts:

  • Science Applications International Corporation (SAIC) Skybus 80K
  • Aeros Aeroscraft Dragon Dream & ML866 / Aeroscraft Gen 2
  • Northrop Grumman / Hybrid Air Vehicles HAV-3 & HAV-304 (LEMV)
  • Hybrid Air Vehicles (HAV) Airlander 10 & 50
  • Lockheed Martin P-791, SkyTug & LMH-1
  • SAIC and ArcZeon International Unmanned Air Systems Carrier
  • Dassault Systemes Commercial Flying Cruise Liner
  • Zeppelin NT 07

The following table presents a summary of some key physical characteristics of these advanced airships.

The largest among this group of airships is the Airlander 50. As a point of reference, the gas envelope on the giant zeppelin Hindenburg was twice as large, at 200,000 cubic meters (7,062,000 cubic feet), but using hydrogen as the lift gas instead of helium as in the modern airships.

Among the airships in the above list, the following have actually flown:  Skybus 80K, Dragon Dream, HAV-304, Airlander 10 prototype, P-791 and the Zeppelin NT 07. As of April 2019, the others in the list were under development or remain as concepts only.  The Zeppelin NT 07 is the only advanced airship in this list that currently is flying regularly in commercial service.  By the early 2020s, we likely will see several additional advanced airships on this list ready for sale to potential customers, the leading candidates being the ML866 / Aeroscraft Gen 2, Airlander 10 and LMH-1.

Now, let’s take a look at the individual advanced airships in this group.

SAIC Skybus 80K

The Skybus 80K was a proof-of-concept, non-rigid airship designed to carry a significant payload and fly autonomously on long duration missions.  The goal of this program was to demonstrate greater persistence over target with a greater payload than was possible using an unmanned drone aircraft.  Lindstrand USA was responsible for the Skybus 80K vehicle primary envelope and flight structure, which is similar in design and operation to a non-rigid Goodyear blimp (the version before the Zeppelin NT model LZ N007-101).  All of the lift is provided by helium and the propeller is used only for propulsion.

SAIC Skybus 80KSkybus 80K. Source: Lindstrand USA

In the Skybus 80K, the gas envelope is divided into a sealed main helium gas volume and separate gas volumes called “ballonets” that contain ambient air at atmospheric pressure.  A simple airship like the Skybus 80K typically would be trimmed for neutral buoyancy.

To takeoff, fans would be used to vent some air from the ballonets, slightly reducing their internal pressure and mass, and allowing the helium gas volume to expand, with the net result of increasing buoyant lift.

As the airship gains altitude, external air pressure decreases, allowing the helium gas volume to expand within the gas envelope, into space previously occupied by the ballonets, which vent a portion of their air content overboard.  The airship reaches its maximum altitude, known as its “pressure height,” when the helium gas volume has expanded to fill the gas envelope and the ballonets are empty.  At this point, the airship’s mass is at a minimum, but the helium lifting gas can expand no further.

To descend, a fan is used to inflate the ballonets with outside air, adding mass and slightly compressing the helium into a smaller volume. This action decreases buoyant lift. As the airship continues to descend into the denser atmosphere, the helium gas volume continues to compress and the ballonets become proportionately larger.  Ballonet inflation is controlled to manage buoyancy as the airship approaches the ground for a landing.

In flight, inflating only the fore or aft ballonet, and allowing the opposite ballonet to deflate, will make the bow or stern of the airship heavier and change the pitch of the airship. These operating principles are shown in the following diagrams of a blimp with two ballonets shown in blue.

Blimp with ballonets (blue).  Source:  zeppelinfan.de

Flying out of Loring Air Force Base in Caribou, Maine, the Skybus 80K met its program objectives for carrying 500 pounds (227 kg) to 10,000 feet (3,048 m) for 24 hours without refueling.  While these may seem to be modest objectives, Skybus 80K was granted the first U.S. certificate for an unmanned experimental airship.  This was an important milestone in the development of optionally manned airships.

You can see a short 2010 video of the Skybus 80K rollout and flight at the following link:

http://lindstrandusaus.com/index.php/videos/mediaitem/49-saic

An SAIC concept for an full-scale optionally manned airship is shown in the following figure.

SAIC optionally manned airship conceptOptionally manned surveillance airship. Source: SAIC

Aeros Aeroscraft Dragon Dream and ML866 / Aeroscraft Gen 2

Igor Pasternak founded Worldwide Aeros Corp. (Aeros) in Montebello, with the goal of becoming a major manufacturer of lighter-than-air (LTA) craft in the U.S.  Today, Aeros LTA products are used globally for military and commercial applications. They include the non-rigid Aeros 40D Sky Dragon airship and advanced tethered aerostatic systems.  The firm’s website is at the following link:

http://aeroscraft.com/aeroscraft/4575666071

In 2011, Aeros was awarded a $60 million contract from Defense Advanced Research Projects Agency (DARPA) for Project Pelican. Under this contract, Aeros developed their half-scale, proof-of-design vehicle named Dragon Dream, which embodied the following design features that also are incorporated on later Aeroscraft airships:

  • Control-of-static-heaviness (COSH) system for variable buoyancy control;
  • Rigid structure, with hard points for mounting the cockpit, propulsion system, aerodynamic control surfaces, and the cargo compartment;
  • Ceiling suspension cargo deployment system for managing cargo with minimal requirements for ground support infrastructure. This system supports cargo containers and pallets from rails in the ceiling of the cargo compartment and adjusts cargo positioning to accommodate changes in center of gravity, such as when other cargo is loaded or unloaded;
  • Air bearing landing system (ABLS) for operation on unimproved surfaces, including ice and water. Airflow in the system can be reversed to provide a suction to grip the ground and hold the airship in place;
  • Vectored thrust engines;
  • Low-speed control (LSC) system for managing the engines and maintaining position and orientation during vertical takeoff and landing (VTOL) and hover in low wind conditions

The aeroshell defines the boundary of the helium envelope.  Within the aeroshell the COSH system manages airship buoyancy using the Helium Pressure Envelopes (HPE, the blue tanks in the following diagram) and Air Expansion Chambers (AEC, the grey bladders).

Aeros Dragon Dream cutaway

Aeroscraft cutaway showing HPE and AEC. Source: Aeros

The COSH variable buoyancy operating principle works as follows:

  • To reduce buoyancy: The COSH system compresses helium from the aeroshell volume into the HPEs, which contain the compressed helium and control the helium pressure within the aeroshell.   The compression of helium into the HPEs creates a negative pressure within the aeroshell, permitting the AECs to expand and fill with environmental air. The greater mass of the air within the aeroshell and the reduced helium lift make the Aeroscraft heavier when desired.
  • To increase buoyancy:The COSH system releases pressurized helium from the HPEs into the aeroshell.  This creates a positive pressure within the aeroshell, causing the AECs to compress and discharge air back to the environment.  With reduced environmental ballast and greater helium lift, overall buoyancy of the Aeroscraft is increased when desired.

Also view a YouTube video describing the operation of the Aeroscraft and its variable buoyancy system here:

https://www.youtube.com/watch?v=8b-qBoFku_o

Dragon Dream was first “float tested” on 3 January 2013 inside a former blimp hanger at the Marine Corps Air Station in Tustin, CA. The airship was rolled out of its hangar on 4 July 2013 and taxi tests were conducted.  All work under Project Pelican was completed within budget in August 2013. The Pentagon declared that the tests of the Dragon Dream were a success, with the craft meeting its demonstration objectives.

On 5 September, Aeros announced that the Federal Aviation Administration (FAA) had granted an R&D Airworthiness Certificate for Dragon Dream, permitting flight testing in designated controlled airspace. Dragon Dream and it made its first flight on 11 September 2013.

Dragon Dream in flight.  Source: AerosDragon Dream in flight.  Source: Aeros

The Dragon Dream airship was damaged in October 2013 when a partial roof collapse occurred while the airship was inside the blimp hanger.  The airship was not repaired.

Aeros claims that the technologies demonstrated by the Dragon Dream will “enable the Aeroscraft to fly up to 6,000 nautical miles, while achieving true vertical takeoff and landing at maximum payload, to hover over unprepared surfaces, and to offload over-sized cargo directly at the point of need.”  Operational Aeroscraft airships will be designed with an internal cargo bay and a cargo suspension deployment system that permits terrestrial or marine (shipboard) delivery of cargo from a hovering Aeroscraft, without the need for local infrastructure.

Aeroscraft cargo delivery systemDischarging cargo from a hovering Aeroscraft airship. Source: Aeros

In September 2015, Aeroscraft CEO Igor Pasternak announced, “We are excited to reveal production is underway on the 555 ft (169 m) long ML866, and (we are) committed to achieving FAA operational certification for the first deployable Aeroscraft in approximately five years.”

Concept drawing, ML866 / Aeroscraft Gen 2 delivering cargo in the Arctic.  Source: Aeros

On 8 August 2018, Aeroscraft announced that “they have completed the preliminary design phase for their Aeroscraft Gen 2 Cargo Airship”……”Aeroscraft Gen 2 will have enhanced buoyancy control, flight surfaces and modular cargo systems.  The aircraft will feature zero emission operations, representing the only truly green technology capable of moving cargo over long distances.  Aeros is now proceeding with the build and test phase on all major systems and subsystems for Aeroscraft Gen 2.”  The Aeroscraft Gen 2 is being designed with great range (3,100 nautical miles; 5,741 km), a cruise speed of 100 – 120 knots, and an altitude ceiling of 12,000 feet (3,658 m).

The basic Aeroscraft design can be scaled up to handle much heavier cargo.  The approximate scaling of an Aeroscraft airship as a function of cargo weight is shown in the following graphic.

Aeroscraft airship scaling to handle larger cargo loads.  Source:  Aeroscraft

Northrop Grumman / Hybrid Air Vehicles HAV-304 (LEMV)

Hybrid Air Vehicles (HAV) was formed in the UK in 2007 after acquiring the rights to airship technologies developed by its predecessor, SkyCat Group Ltd., and earlier predecessors dating back to 1971. The HAV website is here:

https://www.hybridairvehicles.com/about-us

In 2008, the firm built and flew the small, unmanned HAV-3 hybrid airship demonstrator.  The 50 foot (15 meter) long HAV-3 flew from 2008 to 2010 and served to validate the design of the much larger HAV-304 that was proposed by the team of Northrop Grumman and HAV for the U.S. Army’s Long Endurance Multi-Intelligence Vehicle (LEMV) program.

HAV-3 demonstrator in flight.  Source:  HAV via Aviation Week & Space Technology, 5 July 2010

In 2010, the Northrop Grumman / HAV team was awarded the LEMV contract to deploy a large, optionally manned airship capable of flying surveillance missions of up to three weeks duration at 20,000 feet (6,100 m) in uncontested airspace in conflict zones; initially in Afghanistan. An illustration showing the HAV-304 configured for the LEMV mission is shown in the following diagram.

LEMV airship mission concept, serving as a surveillance and communications hub.  Source: US Army / Northrop Grumman

As a hybrid airship, the HAV-304 generated only part of its lift from helium, nominally 60 – 80%.  The balance of the lift is generated by vectored-thrust propellers and by aerodynamic lift from the shaped gas envelope, which acts as a lifting body when the airship has forward speed.  The helium gas envelope is slightly pressurized to maintain its aerodynamic shape. For the LEMV mission, the airship would transit at a maximum speed of 80 knots, and loiter in its designated operating area at 30 knots.

Hybrid airship sources of lift.  Source: DoD 2012

This hybrid airship is negatively buoyant and cannot hover or make a vertical takeoff or landing. The HAV-304 takes off and lands on inflatable skids and requires a takeoff run of less than 1,000 feet (305 m). Airship trim is controlled much like in a conventional blimp, using multiple ballonets located fore and aft in each of the hulls.

The HAV-304 first flew on 7 August 2012 from Joint Base McGuire-Dix-Lakehurst in New Jersey, about 16 months behind its original schedule.  Operations were terminated when the $517 million LEMV contract was cancelled in February 2013: “Due to technical and performance challenges, and the limitations imposed by constrained resources, the Army has determined to discontinue the LEMV development effort.”

Hybrid Air Vehicles bought the airship back from the Army in October 2013 for $301,000 and agreed to give the Army access to data from future civilian flights. After removing LEMV mission-related hardware, HAV returned the HAV-304 airship to the UK to continue developing this airship as the Airlander 10 prototype.

Northrop Grumman LEMV 2012HAV-304 in flight. Source: Northrop Grumman

Hybrid Air Vehicles (HAV) Airlander 10 & 50

The Airlander 10 airship is the commercial reincarnation of the HAV-304 LEMV airship. Airlander 10 currently is the world’s largest aircraft, measuring 302 feet (92 m) long and 143 feet (43.5 m) wide. HAV describes the airship’s construction as follows:

“There is no internal structure in the Airlander – it maintains its shape due to the pressure stabilization of the helium inside the hull, and the smart and strong Vectran material it is made of. Carbon composites are used throughout the aircraft for strength and weight savings.”

A rigid structure running under the gas envelope supports the optionally-manned cockpit, flight control and mission systems, cargo and fuel.  Weight from this rigid module is distributed across every frame of the airship via cables running across and into the hull as well as internal diaphragms.

Maximum payload capacity is 22,050 pounds (10,000 kg), which must be suspended externally from a centerline payload beam.  Maximum speed is 80 kts (148 kph), maximum altitude is 16,000 feet (4,880 m), and manned mission duration is up to 5 days.  Unmanned missions can be significantly longer.

Airlander 10 made its first two flights on 25 August 2016 from Cardington Airfield in Bedfordshire, UK. While the first flight went well, the second ended with an inauspicious soft crash landing with some damage to the airship, but no injuries to the crew.

Airlander 10 first flightAirlander 10 first flight. Source: CNNMoney.Closeup view of Airlander 10 in 2016 showing the side-mounted vectorable-thrust propellers and one of the landing skids.  Source:  Philbobagshot / WikipediaAirlander 10 second landingAirlander 10 soft crash landing after second flight. Source: Sky News

On 13 January 2019, the British Broadcasting Corporation (BBC) reported that HAV had retired the £32 million ($42 m USD) Airlander 10 prototype following successful final testing and achievement of key certification milestones with European civil aviation authorities.

  • Design Organization Approval from the European Aviation Safety Agency (EASA) was received in October 2018
  • Production Organization Approval from the Civil Aviation Authority (CAA) also has been received

HAV reported that, “the prototype served its purpose as the world’s first full-sized hybrid aircraft, providing us with the data we needed to move forward from prototype to production standard…… The full commercial model is expected to take to the skies with its first paying passengers in the early 2020s.”

You’ll find a Royal Aeronautical Society report on the first half of the Airlander 10 testing program, “Expanding the Envelope,” at the following link:

https://www.aerosociety.com/news/expanding-the-envelope/

This report indicates that the all-weather capability of the Airlander 10, including anti-icing, would be tested in the second half of the test program.  The report also suggests that the commercial Airlander 10 may have an enhanced thrust vectoring system that enables a (limited) VTOL capability.

A larger version known as Airlander 50 also is being designed with internal cargo bays capable of carrying up to 132,300 pound (60,000 kg) payloads.  A concept drawing for Airlander 50 is shown below.

Airlander 50 concept drawingAirlander 50. Source: hybridairvehicles.com

More information on Airlander airships is available on the Hybrid Air Vehicles website at the following link:

https://www.hybridairvehicles.com/about-us

Lockheed Martin P-791

The Lockheed Martin P-791 was one of the competitors in the U.S. Army’s LEMV program, which was won by the Northrop Grumman / HAV team with the HAV-304 hybrid airship.

Like the HAV-304, the P-791 tri-lobe hybrid airship flies under the combined influence of thebuoyant lift from helium, vectored thrust from propellers during takeoff and landing, and aerodynamic lift from the shaped gas envelope when the airship is in forward flight.  The gas envelope is slightlypressurized to maintain its aerodynamic shape. The P-791 is not designed for vertical takeoff and landing or hover, since it depends on some aerodynamic lift being generated by the hull.

Rear quarter view of the P-791 in its hanger.  Source:  Al Sieb / Los Angeles Times / TNS

The first flight of the P-791 took place on 31 January 2006 at a Lockheed’s facility in Palmdale, CA.  You can see a short video on the P-791 at the following link:

https://www.youtube.com/watch?v=TrW7EGwYEzg

Lockheed Martin P-791P-791. Source: Lockheed MartinLockheed Martin P-791_2P-791. Source: Lockheed Martin

When the P-791 is on the ground, it is heavier-than-air.   To move the airship on the ground, its air cushion landing system (ACLS) operates in lift mode.  The four air cushion pads on the bottom of the airship allow it to float on cushions of air and use the propulsion system to move the airship over almost any type of surface (pavement, unimproved natural surface like dirt, sand, snow or ice or water).  The ACLS fans can be reversed and operated in suction mode, which enables the airship to “grip” a solid surface and remain stationary during ground cargo handling without the need for ground-based mooring / docking hardware.

You can see a short video on the operation of the ACLS here:

https://www.youtube.com/watch?v=Qi_sJ-k3kRI

Lockheed Martin SkyTug and LMH-1

In March 2011, Lockheed Martin announced that it planned to develop a larger commercial version of the P-971, to be called SkyTug, which would be scaled up to carry at least 20 tons of cargo for the Canadian firm Aviation Capital Enterprises of Calgary.  The first commercial airship was expected to be delivered in 2012, and future versions were expected to have larger cargo carrying capacity.  According to Aviation Capital, “the fully vertical-takeoff-and-landing (VTOL) capable SkyTug will provide ‘greater payload and range at a fraction of the cost of a helicopter’. The larger ships that will follow apparently won’t be fully VTOL – they’ll require something of a run-up on the ground to generate dynamic lift and get airborne, rather as an airplane does.” Evidently, the VTOL version was to have powerful turboshaft engines to provide the needed lift, while the larger versions would have been more conventional hybrid airships.

Lockheed Martin SkyTug hybrid airship concept drawing. Source: Lockheed Martin

By 2015, reference to SkyTug seems to have disappeared and Lockheed Martin was promoting the LMH-1 as their next large commercial hybrid airship based on the P-791 design.  As it currently is described by Lockheed Martin, the LMH-1 is designed to carry a crew of 2, up to 19 passengers or 21 tonnes (21,000 kg / 46,300 lb) of cargo at a maximum speed of 60 kts (111 kph) over a range of 2,593 km (1,400 nautical miles).  The 18 m x 3.2 m x 3 m (59 ft x 10.5 ft x 9.8 ft) cargo compartment is a little bigger than the cargo box of the widely used Lockheed Martin C-130 Hercules fixed-wing cargo aircraft.  The LMH-1 design can be scaled up to carry much heavier cargo.

Lockheed Martin LMH1LMH-1. Source: Lockheed MartinLockheed martin LMH-1_2LMH-1 general arrangement. Source: Lockheed Martin

In November 2015, the U.S. Federal Aviation Administration (FAA) approved Lockheed’s certification plan for the LMH-1.  Lockheed Martin also is working with Transport Canada on plans to a get the airship certified for use in Canada.

Lockheed Martin has engaged the sales firm Hybrid Enterprises to market the LMH-1.  In September 2017, Lockheed Martin claimed it had Letters of Intent for 24 LMH-1 airships. First flight of the production airship is expected in 2019.

You can view a short video on the LMH-1 hybrid airship here:

https://www.lockheedmartin.com/en-us/products/hybrid-airship.html

An LMH-1 hybrid airship flying in the Arctic – concept drawing. Source:  Lockheed Martin

SAIC and ArcZeon International Unmanned Air Systems (UAS) Carrier

Small, unmanned air vehicles (UAV), now commonly called unmanned air systems (UAS), can carry advanced sensors and weapons, but generally have short range.  In spite of their range limitations, UASs can provide valuable and cost-effective capabilities for military planners and war fighters. At a recent conference is Washington D.C., DARPA Deputy Director Steve Walker asked the following question:  “With the ranges we are looking at in the Pacific Theater, how do we get our small UAS to the fight?”  Actually, he already knew the answer.

In March 2016, DARPA awarded the first contracts in support of its Gremlins program, which DARPA describes as:

“Gremlins (program)…… seeks to develop innovative technologies and systems enabling aircraft to launch volleys of low-cost, reusable unmanned air systems (UASs) and safely and reliably retrieve them in mid-air. Such systems, or “gremlins,” would be deployed with a mixture of mission payloads capable of generating a variety of effects in a distributed and coordinated manner, providing U.S. forces with improved operational flexibility at a lower cost than is possible with conventional, monolithic platforms.”

While the primary launch / recovery vehicle for this phase of the Gremlins program is a C-130 Hercules turboprop transport aircraft, the UAS launch and recovery techniques developed by the Gremlins program may be adaptable to other types of air vehicles, such as airships.  Read more on the DARPA Gremlins program at the following link:

https://www.darpa.mil/program/gremlins

SAIC and ArcZeon International, LLC proposed a UAS carrier airship for this type of mission.  A concept drawing for such an airship is shown below. No contract was awarded for development of this airship concept.

Airship launching UAS swarmAirship deploying UAS. Source: SAIC / ArcZeon

Dassault Systems Commercial Flying Cruise Liner

The French firm Dassault Systemesposted an evocative advertisement in the a July 2016 issue of Aviation Week & Space Technologymagazine, with the following tag line:

“If we go on a cruise, does it have to be at sea level?”

Dassault flying cruise liner 1e Source: Dassault Systemes / Raybrennancreative.com

The image of a lighter-than-air cruise ship flying over snow-capped mountains looks like an airship builders dream from the mid-1930s, but with a distinctly modern airship design.  The print ad concluded with the question:

“How long before the sky becomes the destination?”

While Dassault Systemes is not in the business of building airships, they have developed an integrated system called the 3DExperience platform to assist clients in developing “compelling consumer experiences.”  I hope one of their clients likes the idea of a flying cruise liner.  Let’s take a closer look at the airship.

Dassault flying cruise liner 2 cropSource: Dassault Systemes / Raybrennancreative.com

Very nice!!

Zeppelin NT

The closest you can come to an airship cruise today is a short commercial flight aboard a 12 – 14 passenger Zeppelin NT 07 airship, which is very similar in design to the new Goodyear airships.  Friedrichshafen, Germany, home of the original Zeppelin factory, is the home base for Zeppelin NT.

The Zeppelin NT is longer than a Boeing 747-400 airliner.  The airship’s primary structure weighs only about 1,000 kg (2,200 lbs) and the empty weight of a Zeppelin NT is about 6,622 kg (5,181 lb). In comparison, the empty weight of a Boeing 747-400 is 184,567 kg (406,900 lb).

Zeppelin NT & Boeing 747-400 size comparison. Source: Zeppelin NT

In normal operation, the Zeppelin NT operates with a slight negative buoyancy (i.e., the gas cells do not create enough buoyancy to make the Zeppelin NT lighter-than-air). At takeoff and landing, negative buoyancy is overcome with the application of engine power to three propellers (two flank, one stern) that have been vectored to generate the needed lift and some forward momentum. As forward speed increases, some aerodynamic lift is generated by the aeroshell and the propellers are rotated to deliver only propulsive thrust.

You’ll find detailed descriptions of the Zeppelin NT here:

https://www.airships.net/zeppelin-nt/

and here:

http://www.blimpinfo.com/wp-content/uploads/2012/01/Technical-data-of-the-Zeppelin-NT-07.pdf

In 2011 Goodyear replaced its aging fleet of GZ-20A non-rigid airships (blimps) with Zeppelin NT model LZ N007-101 semi-rigid airships. However, the name “Goodyear blimp” is still being used.  You’ll find a very good illustrated history of the Goodyear blimp at the following link

http://www.goodyearblimp.com/relive-history/#page/2

Goodyear’s new “blimp” – the semi-rigid Zeppelin LZ N007-101. Source: Goodyear

My wife and I took a flight on the Zeppelin NT in early June 2017, on a clear blue sky day, one day after a modest wind and rain storm had passed through the Friedrickshafen area and temporarily grounded zeppelin flight operations.  Clearly, weather is much more of an issue for flying zeppelins than it is for winged heavier-than-air craft.  Nonetheless, in suitable weather conditions, flight in a zeppelin is a remarkable experience.  Our short tourist flight in the Zeppelin NT was hardly an adequate basis for a zeppelin commercial business model.  However, based on this flight, it’s much easier for me to visualize the utility of a large commercial airship for delivering cargo, passengers and emergency services to remote areas that are harder to reach with other modes of transportation.

One of the Zeppelin NT airships at the airfield in Friedrichshafen. Source:  Author’s photoPreparing to land and change passengers.  Source: Author’s photoTakeoff with flank thrusters in the vertical position for lift. Source:  Author’s photoView of the German countryside from Zeppelin-NT.  Source:  Author’s photoView of Lindau on Lake Constance (the Bodensee) from Zeppelin-NT.  Source:  Author’s photoView of German countryside from Zeppelin-NT. Source: zeppelin-nt.de

You can book your flight on a Zeppelin NT at the following link:

http://zeppelin-nt.de/en/homepage.html

 

How Long Does it Take to Certify a Commercial Airliner?

After designing, developing, and manufacturing a new commercial airliner, I’m sure the airframe manufacturer has a big celebration on the occasion of the first flight. The ensuing flight test and ground static test programs are intended to validate the design, operating envelope, and maintenance practices and satisfy these and other requirements of the national certifying body, which in the U.S. is the Federal Aviation Administration (FAA). Meanwhile, airlines that have ordered the new aircraft are planning for its timely delivery and introduction into scheduled revenue service.

The time between first flight and first delivery of a new commercial airliner is not a set period of time. As you can see in the following chart, which was prepared by Brian Bostick (http://aviationweek.com/thingswithwings), there is great variability in the time it takes to get an airliner certified and delivered.

Time to certify an airliner

In this chart, the Douglas DC-9 has the record for the shortest certification period (205 days) with certification in November 1965. The technologically advanced supersonic Concorde had one of the longest certification periods (almost 2,500 days), with authorization in February 1976 to conduct a 16-month demonstration period with flights between Europe and the U.S. before starting regular commercial service.

The record for the longest certification period goes to the Chinese Comac ARJ21 twin-jet airliner, which is the first indigenous airliner produced in China. The first ARJ21 was delivered to a Chinese airline in November 2015. The ARJ is based on the DC-9 and reuses tooling provided by McDonnell Douglas for the licensed production of the MD-80 (a DC-9 variant) in China. I suspect that the very long certification period is a measure of the difficulty in establishing the complete aeronautical infrastructure needed to deliver an indigenous commercial airliner with an indigenous jet engine.

In the chart, compare the certification times for the following similar commercial airliners:

  • Four-engine, single aisle, long-range airliners: Boeing 707 (shortest), Douglas DC-8, Convair CV-880, Vickers VC-10, De Havilland Comet (longest)
  • Three-engine, single aisle, medium range airliners: Boeing 727 (shorter), Hawker Siddeley Trident (longer)
  • Two-engine, single aisle airliners: Douglas DC-9 (shortest), Boeing 737, Boeing 757, Airbus A320, British Aircraft Corporation BAC 1-11, Dassault Mercure, Caravelle (longest)
  • Two-engine, single aisle, short range regional jets: Embraer ERJ 145 (shortest), Bombardier CRJ-100, BAe 146, Fokker F-28, ERJ 170, Bombardier CS Series, Mitsubishi MRJ, Sukhoi Superjet, VFW-614, Comac ARJ21 (longest)
  • Four-engine, wide-body, long-range airliners: Boeing 747, Airbus A340, Airbus A380 (longest)
  • Three-engine, wide-body, long-range airliners: Douglas DC-10 (shorter), Lockheed L-1011 (longer)
  • Two-engine, wide-body airliners: Boeing 767 (shortest), Boeing 777, Airbus 350, Airbus A300, Boeing 787 (longest)

Time is money, so there is tremendous economic value in minimizing the time between first flight and first delivery. The first 16 aircraft at the top of the chart all enjoyed relatively short certification periods. This group, which includes many aircraft that appeared in the 1960s – 70, averaged about 400 days between first flight and first delivery.

More modern aircraft (blue bars in the chart representing aircraft appearing in 2000 or later) have been averaging about 800 days between first flight and first delivery (excluding ARJ21).