Category Archives: Transportation

Modern Airships – Part 1

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 79 individual articles on historic and advanced airship designs.  This is Part 1.  Here are the links to the other two parts:

You’ll find a consolidated Table of Contents for all three parts at the following link.  This should help you navigate the large volume of material in the three documents.

Modern Airships – Part 1 begins with an overview of modern airship technology, continues with a summary table identifying the airships addressed in this part, and concludes by providing links to 22 individual articles on these airships. A downloadable 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:  PL31416@cox.net.

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

August 2019

2.  Well-established benefits and opportunities, but a risk-averse market

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 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 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.

This matter 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 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 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 August 2019, 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 Airshipsin 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 to 100 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, detailed designs, the first to secure adequate funding will be able to take the next steps to build a manufacturing facility and a full-scale prototype airship, complete the airship certification process, and start offering a certified airship for sale.

There are a some significant roadblocks in the way:

  • No full-scale prototypes are flying:  The 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.
  • Immature manufacturing capability:  While the airship industry has been good at developing many advanced designs, some existing 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.  Several years ago, 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, hanger 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 early 2020s, when several different heavy-lift 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.

In the US, the Federal Aviation Administration’s (FAA) 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:

https://www.faa.gov/aircraft/air_cert/design_approvals/airships/airships_regs/media/aceAirshipDesignCriteria.pdf

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:

https://www.faa.gov/documentlibrary/media/advisory_circular/ac_21-17-1a.pdf

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 that cannot possibly be handled by a non-rigid airship.

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-engined 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 m3or more, whichever is greater.”

These supplementary requirements are contained in the document “Transport Airship Requirements” (TAR), dated March 2000, which you will find at the following link:

https://www.faa.gov/aircraft/air_cert/design_approvals/airships/airships_regs/media/aceAirshipTARIssue1.pdf

So, this is the status of US and European airship regulations today.  

In the US, Lockheed-Martin currently is in the process of working with the FAA to get a type certificate for their semi-buoyant, hybrid airship, the LMH-1.  Clearly, they are dealing with great regulatory uncertainty.  Hopefully, the LMH-1 type certification effort will be successful and serve as a precedent for later applicants. 

4. Lifting gas

In the US, Canada and Europe, 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)

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.

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. Helium is not “rare.” 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 submitted in 2010 and posted 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.  BASI claims that lifting gas cells designed originally for helium lifting gas cannot later be used with hydrogen lifting gas.

Regulatory changes will be required to permit the general use of hydrogen lifting gas in commercial airships.  Time will tell if that change ever occurs.

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

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 powered airships are described in this section:  

  • Conventional airships
  • Semi-buoyant airships and aircraft
  • Variable buoyancy airships
  • Helistats (airship – helicopter hybrid)  
  • Thermal (hot air) airships

5.1  Conventional airships

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 non-rigid blimps, rigid zeppelins, and semi-rigid airships.

  • Non-rigid airships (blimps): These airships have a flexible envelope that defines the shape of the airship, contains the lifting gas cells and ballonets for buoyancy management, and supports the load of a gondola, engines and payload.
  • Rigid airships (zeppelins):These airships have a lightweight, rigid airframe that defines their exterior shape.  The rigid airframe supports the gondola, engines and payload.  Lifting gas cells and ballonets are located within the rigid airframe.
  • Semi-rigid airships:  These airships have a rigid internal spine or structural framework that supports loads. A flexible envelope is installed over the structural framework and contains the lifting gas cells and ballonets.

The Euro Airship DGPAtt and the Flying Whales LCA60T are examples of rigid conventional airships.

The Zeppelin NT and the SkyLifter are examples of semi-rigid conventional airships.

After being loaded and ballasted before flight, conventional airships have various means to control the in-flight buoyancy of the airship. Control can be exercised over ballast, lifting gas and the ballonets as described below.

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 / discharging cargo or passengers) can change the overall mass of an airship and may require a corresponding ballast adjustment. If an airship is heavy and the desired buoyancy can’t be restored with the ballonets or other means, ballast can be removed on the ground or may need to be dumped in flight to increase buoyancy.

Controlling  buoyancy with lifting gas:  

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 inside an airship’s gas cells is at atmospheric pressure.  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.  

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 the ballonets or lifting gas coolers, it is possible to vent some lifting gas to the atmosphere to decrease aerostatic lift. 

Controlling  buoyancy with ballonets:

The airship hull / envelope is divided into sealed lifting gas volumes and separate gas volumes called “ballonets” that contain ambient air. The ballonets are used to compensate for modest changes in buoyancy by inflating them with small fans or venting them to the atmosphere to change the gross weight of the airship.  Fore and aft ballonets can be operated individually to adjust the trim (pitch angle) of the airship. 

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 air in 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 and the helium lifting gas can expand no further.

On the ground, the ballonets may be inflated with air to make the airship negatively buoyant (heavier-than-air) to simplify ground handling. To takeoff, the ballonets would be vented to the atmosphere, reducing the mass of air carried by the airship.

To descend, a low-pressure fan is used to inflate the ballonets with outside air, adding mass. As the airship continues to descend into the denser atmosphere, the helium gas volume continues to contract and the ballonets become proportionately larger, carrying a larger mass of air.  Ballonet inflation / venting 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, which are shown in blue.

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

5.2  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 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 two types of hybrid airships:  semi-rigid and rigid.  

  • Semi-rigid hybrid airships:  These airships have a structural keel or spine to carry loads, and a large, lifting-body shaped inflated fuselage containing the lifting gas cells and ballonets.  Operation of the ballonets to adjust net buoyancy and pitch angle is similar to their use on conventional airships.  These wide hybrid airships may have separate ballonets on each side of the inflated envelope that can be used to adjust the roll angle.  While these airships are heavier-than-air, they generally require adjustable ballast to handle a load exchange involving a heavy load.
  • Rigid hybrid airships:  These airships have a more substantial 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 an inflated fuselage of a semi-rigid airship. Otherwise, the rigid hybrid airship behavior is similar to a semi-rigid airship. 

The Lockheed-Martin LMH-1 is an example of a semi-rigid hybrid airship.  The AeroTruck being developed by Russian firm Airship GP is an example of a rigid hybrid airship.

5.3  Semi-buoyant aircraft

Semi-buoyant aircraft 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 aircraft 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 aircraft 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 aircraft.

5.4  Variable buoyancy airships

Variable buoyancy airships are rigid airships that can change their net lift, or “static heaviness,” to become LTA or HTA 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 net lift of a fixed volume airship.  For example, a variable buoyancy / fixed volume airship can become heavier by compressing the helium lifting gas or ambient air:

  • 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 tanks:

  • Compressed helium lifting gas is vented back into the helium lift 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 Dreamand the Varilift ARH-50 are examples of variable buoyancy / fixed volume airships.

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.
  • Likewise, 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 EADS Tropospheric Airship is an example of a variable buoyancy / variable volume airship.

5.5 Helistats (airship / helicopter hybrid)

There have been many different designs of airship / helicopter hybrid aircraft (a helistat) in which the airship part of the hybrid aircraft carries the weight of the aircraft itself and helicopter rotors deployed around the base of the airship work in concert to propel the aircraft and to lift and deliver heavy payloads without the need for an exchange of ballast.

The Piasecki PA-97 and the Boeing  / Skyhook International SkyHook JLH-40 are examples of helistats.

5.5 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.

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 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.”

This requirement 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 a 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. This 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 conducting a precision airborne load exchange.

You’ll find more information on airship load exchange issues in a December 2017 paper by Charles Luffman, entitled, “A Dissertation on Buoyancy and Load Exchange for Heavy Airships (Rev. B)”, which is available at the following link:  

https://www.luffships.com/wp-content/uploads/2018/02/buoyancy_and_load_exchange.pdf

7. The scale of large cargo airships

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 fixed-wing cargo aircraft.

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

8. Specific airships in Part 1

The airships reviewed in Part 1 are summarized in the following set of tables, which include many heavy-lift cargo airships. In addition, there are several examples of semi-buoyant aircraft, helistats and thermal (hot air) airships.  Links to the 22 individual articles on these airships are provided at the end of this document.

The CargoLifter CL160, helistats, Megalifter, Aereon Dynairship and Project Walrus are included because they are of historical interest as early, though unsuccessful, attempts to develop large cargo airships. Concepts and technologies developed on these airship projects have promoted the development of other modern airships.

Among the airships in the above tables, the following have flown:  

  • Zeppelin NT 07 
  • Skybus 80K
  • Aeros Aeroscraft Dragon Dream
  • Piasecki PA-97
  • Dynalifter DL-100
  • Aereon 26
  • ATG / SkyCat Group SkyKitten
  • Hybrid Air Vehicles HAV-3 & HAV-304
  • Hybrid Air Vehicles Airlander 10
  • Lockheed Martin P-791
  • Volaris 901 & 902
  • GEFA-Flug AS-105GD/4 & AS-105GD/6 
  • Skyacht Personal Blimp

As of August 2019, the Zeppelin NT 07 is the only advanced airship that has been certified and is flying regularly in commercial passenger service.  The simpler GEFA-Flug and Skyacht thermal (hot air) airships also are flying regularly. The others that have flown have been retired.  The remaining airships in the Part 1 tables are under development or remain as concepts only. 

Among the airships in the above tables, several cargo airships are likely to receive their airworthiness certification in the next several years. The leading candidates identified in Part 1 are:

  • Lockheed Martin: LMH-1 hybrid airship
  • Hybrid Air Vehicles (HAV): Airlander 10 hybrid airship
  • Aeros Aeroscraft: ML866 / Aeroscraft Gen 2 variable buoyancy airship
  • Volaris: V932 NATAC semi-buoyant airship

These airships will be competing in the worldwide airship market with the leading candidates identified in Part 2, which may enter the market in the same time frame:

  • Flying Whales: LCA60T rigid airship
  • Varialift:  ARH-PT variable buoyancy airship prototype and the larger ARH 50
  • Euro Airship:  Corsair & DGPAtt variable buoyancy airships
  • Solar Ship: 24-meter Caracal light cargo semi-buoyant airship and the Wolverine medium cargo semi-buoyant aircraft
  • Egan Airships:  The PLIMP drone and Model J plane / blimp hybrids

All of these candidates depend on a source of funding to bring their designs to market. 

The early 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 airworthiness certificates will be enough to open a new era in airship transportation. Aviation regulatory agencies need to help reduce risk by eliminating 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.

9. Links to the individual articles

The following links will take you to the 22 individual Modern Airships – Part 1 articles.  Note that the following articles address more than one airship that appeared in the preceding graphic tables:  Aereon, Aeros, Helistats, Hybrid Air Vehicles, Ohio Airships and Voliris.

Conventional airships:

Variable buoyancy, fixed volume airships:

Helistats (airship / helicopter hybrid):

Hybrid, semi-buoyant aircraft:

Hybrid, semi-buoyant airships:

Thermal (hot air) airships:

Modern Airships – Part 3

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 79 individual articles on historic and advanced airship designs. This is Part 3.  Here are the links to the other two parts:

You’ll find a consolidated Table of Contents for all three parts at the following link.  This should help you navigate the large volume of material in the three documents.

Modern Airships – Part 3 begins with a summary table identifying the airship concepts addressed in this part, and concludes by providing links to 32 individual articles on these airship concepts. A downloadable copy of Part 3 is available here:

If you have any comments or wish to identify errors in this document, please send me an e-mail to:  PL31416@cox.net.

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

August 2019

2. Specific airship concepts in Part 3

The airships described in Part 3 are relatively exotic concepts in comparison to the heavy-lift cargo airships that dominate Parts 1 and 2.  Many of the airship concepts in Part 3 are designed for operation with very low or no carbon emissions.  I’ve grouped these airship concepts based on their applications rather than on their design / type because sometimes those details are difficult to determine when few graphics and limited descriptions are available.  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.

The airship design concepts reviewed in Part 3 are summarized in the following set of tables.  Except for a few sub-scale models, none of these airship concepts have flown.  Links to individual articles on these airships are provided at the end of this document.

3. Links to the individual articles

The following links will take you to 32 individual articles.  Note that the Avalon Airships article addresses all three of their airship design concepts, which are listed separately in the above tables and in the following index.

Cargo & multi-purpose airships

Mass transportation airships:

Flying hotel airships:

Touring airships:

Flying yacht airships:

Remotely-piloted special purpose airship:

Personal airships:

Thermal (hot air) airships:

Other novel designs:

Modern Airships – Part 2

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 79 individual articles on historic and advanced airship designs. This is Part 2.  Here are the links to the other two parts:

You’ll find a consolidated Table of Contents for all three parts at the following link.  This should help you navigate the large volume of material in the three documents.

Modern Airships – Part 2 begins with a summary table identifying the airship concepts addressed in this part, and concludes by providing links to 25 individual articles on these airship concepts. A downloadable copy of Part 2 is available here:

The links to the individual articles are at the end of this document.

If you have any comments or wish to identify errors in this document, please send me an e-mail to:  PL31416@cox.net.

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

August 2019

2. Specific airships in Part 2

The airships reviewed in Part 2 are summarized in the following set of tables.  There are many heavy-lift cargo airships in these tables. In addition, there are several solar-powered airships and sub-scale airships that demonstrated novel means of airship propulsion.  Links to the individual articles on these airships are provided at the end of this document.

Among the airships in the above tables, the following full-scale airships have flown:

  • Project Sol’R Nephelios solar-powered airship
  • Solar Ship 20-meter Caracal prototype
  • Solomon Andrews’ Aereon I and II variable buoyancy propulsion airships (in the 1860s)

In addition, the following sub-scale demonstrators have flown:

  • Festo b-IONIC Airfish (demonstration of ionic propulsion)
  • Phoenix and AHAB (demonstrations of variable buoyancy propulsion)

Among the airships in the above tables, several airships are likely to receive their airworthiness certification in the next several years. The leading candidates identified in Part 2 are:

  • Flying Whales: The LCA60T prototype maiden flight is expected to take place in 2021, and the firm appears to have the funding needed to enter full-scale production.
  • Varialift:  The ARH-PT prototype’s first “float test” is expected in 2019.  The first ARH 50 roll out is expected in 2021, with a 24-month certification process before commercial deliveries begin.
  • Euro Airship: Production-ready drawings exist for the Corsair and the larger DGPAtt.  When funding becomes available, they’re ready to go.
  • Solar Ship: The 24-meter Caracal semi-buoyant, inflated wing airship and the larger Wolverine semi-buoyant aircraft are expected to receive Canadian certification, possibly by 2020 – 2021.
  • Egan Airships:  The PLIMP drone and Model J plane / blimp hybrids that have started their FAA certification processes.

These airships will be competing in the worldwide airship market with the leading candidates identified in Part 1, which may enter the market in the same time frame:

  • Lockheed Martin: LMH-1 hybrid airship
  • Hybrid Air Vehicles (HAV): Airlander 10 hybrid airship
  • Aeros Aeroscraft ML866 / Aeroscraft Gen 2: variable buoyancy airship
  • Volaris V932 NATAC: semi-buoyant, inflated wing airship

The early 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 airworthiness certificates will be enough to open a new era in airship transportation. Aviation regulatory agencies need to help reduce risk by eliminating 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.

3. Links to the individual articles

The following links will take you to the 25 individual articles.  Note that the Atlas / Augur RosAeroSystems, Solar Ship, Egan Airships, and variable buoyancy propulsion articles addressed all of the related airship designs, some of which were listed separately in the preceding tables.

Conventional airships:

Variable buoyancy, fixed volume airships:

Variable buoyancy, variable volume airships:

Hybrid, semi-buoyant airships:

Hybrid, solar-powered airships

Plane / blimp hybrids:

Solid-state propulsion airship:

Variable buoyancy propulsion airships:

The Huge Scale of the Latest Generation of Wind Turbines is Challenging Available Manufacturing and Transportation Infrastructure

In an effort to improve the generating and economic performance of wind turbines, manufacturers have been designing and building increasingly larger machines.  Practical limits on transporting these very long and heavy components between the factories and the installation sites may limit the scale of the wind turbines selected for some applications and may require novel solutions that affect component design, factory siting and choice of transportation mode.  In this post, we’ll take a look at these issues.

1. The latest generation of wind turbines

1.1 GE Cypress platform

On 13 March 2019, General Electric (GE) Renewable Energy announced that its largest onshore wind turbine prototype, named Cypress, started commercial operation in the Netherlands.  Unlike other large wind turbines, the prototype Cypress composite turbine blades come in two pieces and are assembled on site. Cypress was announced in September 2017 and construction of the prototype began in 2018.

The 5.3 MW Cypress prototype wind turbine. Source:  GE

The Cypress 5.3-158 prototype has a nominal generating capacity of 5.3 MW.  A smaller Cypress 4.8-158 (with a 4.8 MW rating) is currently under production at GE’s Salzbergen, Germany factory, and it is expected to be commissioned by the end of the 2019.  Both have a rotor diameter of 158 meters (518.3 ft).

Anatomy of a GE Cypress wind turbine. Source:  GE

GE reports that the Cypress platform is “powered by a revolutionary two-piece blade design that makes it possible to use larger rotors and site the turbines in a wider variety of locations. The Annual Electricity Production (AEP) improvements from the longer rotors help to drive down Levelized Cost of Electricity (LCOE), and the proprietary blade design allows these larger turbines to be installed in locations that were previously inaccessible.” Site accessibility can be limited by the practicality of ground transportation of single-piece blades that can be nearly 91.4 meters (300 feet) long.

1.2 GE LM 88.4 P, the longest one-piece rotor blade in the world

LM Wind Power, a GE Renewable Energy business, has delivered the longest one-piece wind turbine blades built to date, the LM 88.4 P, which measure 88.4 meters (290 ft) long.  Three of these giant blades are installed onshore in Denmark on an Adwen’s AD 8-180 wind turbine, which has an 8 MW nominal generating capacity and a 180 meter (590.5 ft) rotor diameter.  You can get a sense of the size of an LM 88.4 P in the following photo showing a rotor blade leaving the factory.

88.4 meter (290 ft) LM 88.4 P wind turbine rotor blade 
leaving the factory.  Source: LM Wind Power

1.3 GE Haliade-X platform

GE is developing an even larger wind turbine platform, the Haliade X, which will become the world’s largest wind turbine when it is completed.  This 12 MW platform, which is being developed primarily for offshore wind farms, features 107 meter (351 ft) long one-piece blades and a 220 meter (722 ft) rotor diameter. The first prototype unit will be installed onshore near Rotterdam, Netherlands, where it will stand 259 meters (850 ft) tall, from the base of the tower to the top of the blade sweep.

Anatomy of a GE 12 MW Haliade-X wind turbine. Source: GE

Construction of the prototype Haliade-X wind turbine began in 2019.  The first blade is shown in the photo below. After securing a “type certificate” for the Haliade-X platform, GE plans to start selling this wind turbine commercially as early as 2021. The near-term market focus appears to be new wind turbines sited in the North Sea.

The first 107 meter (351 ft) Haliade-X blade at the factory in Cherbourg, France.  Source GE Renewable Energy

1.4 Siemens Gamesa SG 10.0-193 DD platform

In January 2019, Siemens Gamesa launched its next generation (Generation V) of very large offshore wind turbines, the SG 10.0-193 DD, which has a nominal generator rating of 10 MW, blade length of 94 meters (308 ft) and a rotor diameter of 193 meters (633 ft).  The nacelle housing the wind turbine hub and generator weighs up to 400 tons.

You’ll find the Siemens product brochure for this Generation V wind turbine here: https://www.siemensgamesa.com/en-int/-/media/siemensgamesa/downloads/en/products-and-services/offshore/brochures/siemens-gamesa-offshore-wind-turbine-sg-10-0-193-dd-en-double.pdf

The 10 MW Siemens SG 10.0-193 DD. Source: Siemens Gamesa

1.5 Vestas EnVestusTM platform

The EnVestusTM platform, which was introduced in 2019, is Vestas’ next generation in its evolution of wind turbines. The V162-5.6 MW has a rotor diameter of 162 meters (531 ft), which is the largest rotor size offered in the current EnVestusTM product portfolio.  Various tower sizes are offered, with hub heights up to 166 meters (545 ft).  With this tallest tower, the blade sweep of a V162-5.6 MW wind turbine reaches a height of 247 meters (810 ft).

V162-5.6 MW nacelle.  Source:  Vestas

The trend in Vestas wind turbine maximum rotor size is evident in the following diagram.  In comparison, the largest GE wind turbine, the Haliade-X will have a rotor diameter of 220 meter (722 ft), and the largest Siemens Generation V wind turbine will have a rotor diameter of 193 meters (633 ft).  

Source: Vestas

You can read and download the EnVestusTMproduct line brochure here: https://nozebra.ipapercms.dk/Vestas/Communication/Productbrochure/enventus/enventus-product-brochure/?page=1

2. Transporting very large wind turbine components

The manufacturer’s efforts to improve wind turbine generating and economic performance has resulted in increasingly larger machine components, which are challenging the limits of today’s transportation infrastructure as the components are moved from the manufacturer’s factories to the installation sites.  Here, we’ll look at the various ways these large components are transported.

2.1 Transportation of wind turbine components by land

Popular Mechanics reported that, “Moving long turbine blades is such a logistical nightmare that the companies involved sometimes resort to building new roads for the sole purpose of moving blades.” Transporting wind turbine tower and nacelle components can be equally challenging.  You’ll find an interesting assessment by CGS Labs of the challenges of wind farm ground transportation planning at the following link: https://www.cgs-labs.com/Software/Autopath/Articles/Windturbinetransport.aspx

As noted previously, the GE one-piece LM 88.4 P, which is 88.4 meters (290 ft) long, is the longest wind turbine rotor blade currently in service.  You can watch a short video of a single LM 88.4 P blade being transported 218 km (135 miles) to the construction site at the following link.  Total transport weight was 60 tons (120,000 lb, 54,431 kg). https://www.lmwindpower.com/en/products-and-services/blade-types/longest-blade-in-the-world

88.4 meter (290 ft) LM 88.4 P wind turbine blade during transport. 
Source: Screenshot from LM Wind Power video

Specialized trucks are employed to negotiate existing roads. Examples of difficult transportation situations are shown in the following photos.

Siemens 75 m (243 ft) rotor blade was transported 320 km (199 miles) by road.  Source: utilities-me.com, 14 Aug 2012
Making a sharp turn with a specialized truck for transporting a
 Vestas V117 57.5 meter (189 ft) wind turbine blade.  
Source: CNN.com, 5 October 2017

Watch a short 2017 video of this maneuver here:  https://www.youtube.com/watch?v=rxvuMv2MED0

Specially-designed trucks move 52.4 meter (172 foot) long wind turbine blades on narrow roads on Baoding Mountain in China.  Source:  Business Insider, 2 Mar 2017

Watch a short 2015 video of this amazing truck convoy here:  https://www.youtube.com/watch?v=1cnHui4pFBU

2.2. Transportation of wind turbine components by sea

The single-piece blades for the GE Haliade X wind turbine are so long that they couldn’t be transported by land from GE’s existing factories.  Therefore, a new LM Wind Power blade factory for the offshore wind market was built in Cherbourg, France, on the banks of the English Channel in Normandy.  This factory can load blades directly onto ships for delivery to offshore wind turbine sites.

GE wind turbine blades shipped by sea.  
Source:  LM Wind Power

In December 2016, Siemens Gamesa reported, “When our new factories in Hull, England and Cuxhaven, Germany become fully operational, and both Ro-Ro (“roll-on, roll-off”) vessels are in service as interconnection of our manufacturing and installation network, we expect savings of 15-20 percent in logistics costs compared to current transport procedures. This is another important contributor reducing the cost of electricity from offshore wind.”

The Hull, UK rotor blade factory, located at the Alexandra Docks on the harbor, was completed in 2016.  The Esbjerg, Denmark factory also is located on the harbor with direct access to shipping.

In 2018, Siemens Gamesa opened its modern factory in Cuxhaven, Germany for manufacturing offshore wind turbine nacelles.  These three Siemens wind turbine factories have direct Ro-Ro access to shipping.In November 2016, Siemens commissioned its first specialized Ro-Ro transport vessel, the Rotra Vente.  This ship is designed to transport multiple heavy nacelles, or up to nine tower sections, or three to four sets of rotor blades, depending on what else is being transported.  A second specialized Ro-Ro transport vessel, the Rotra Mare, was commissioned in the spring of 2017 to transport tower sections and up to 12 rotor blades.  These specialized transport vessels link the Siemens factories and transport the finished wind turbine components to the respective installation harbor.

The Rotra Vente provides Ro-Ro access for large Siemens wind turbine components.  Source: Siemens

2.3. Transportation of wind turbine components by airship

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 heavy-lift roles.  One such role is the transportation of large wind turbine components.  Airships offer the potential to transport the components quickly between factory and installation site without the constraints of current ground and sea transportation networks.

Three examples of airship concepts for transporting wind turbine components are described below. 

Hybrid airships

In 2017, Lockheed-Martin proposed its LMH-1 hybrid airship to deliver large wind turbine components weighing up to 23.5 tons (47,000 lb; 21,000 kg).  The LMH-1 will be capable of flying 1,400 nautical miles (2,593 km) at a speed of about 70 knots (80 mph, 129 kph).  Lockheed-Martin is expected to fly the commercial prototype of its LMH-1 hybrid airship in 2019. You can read Lockheed-Martin’s proposal for airship transport of wind turbine components here: https://www.lockheedmartin.com/content/dam/lockheed-martin/eo/documents/webt/transporting-wind-turbine-blades.pdf

This type of airship conducts short takeoff and landing (STOL) operations when transporting heavy loads, but can operate from relatively unprepared sites.  When off-loading heavy cargo, this airship must take on ballast at the landing site. 

After LMH-1, Lockheed Martin has plans to build a medium-size (90 ton cargo) hybrid airship that would be more competitive with trucking and rail transport.  

Anatomy of the LMH-1 hybrid airship.  Source:  Lockheed Martin

Variable buoyancy airships

In January 2013, Worldwide Aeros Corp. (Aeros), located in Montebello, CA, conducted the first “float test” of their Dragon Dream variable buoyancy airship.  More recently, Aeros has reported that they are working on the first commercial prototype of a larger variable buoyancy airship to be known as the ML866 / Aeroscraft Gen 2, which will be 169 meters (555 ft) long.  This airship is being designed with great range (3,100 nautical miles; 5,741 km) and a cruise speed of 100 – 120 knots.  The ML866 will have a cargo capacity of 66 tons (132,000 lb; 59,874 kg).  The first ML866 prototype is not expected to fly before the early 2020s.

This type of airship is designed to conduct vertical takeoff and landing (VTOL) operations with a full cargo load, and can hover above a site and take on or deliver cargo without landing and without transferring ballast to/from the ground site.

Concept drawing of an Aeroscraft variable buoyancy airship delivering wind turbine blades to a site.  Source: Worldwide Aeros Corp.

Semi-rigid airships

The KNARR initiative is a project created by two Danish design architects, Rune Kirt and Mads Thomsen to design a freight solution using modern airships to reduce the cost and energy consumption of today’s wind turbine freight business and make the logistics for wind turbine freight simpler and more efficient.  Their main point is that transportation and installation costs can be up to 60% of the total cost of a new wind turbine, and these activities have a large carbon footprint.  Their solution is a modern airship that is designed specifically for transporting very large and heavy wind turbine components directly from the manufacturer’s factory to the installation  site. For their work, they were awarded both the Danish Design Center’s Special Prize and the International Core77 Design “Speculative Concept.”.  You can read more about the firm, KIRT x THOMSEN aps, and the KNARR initiative here: https://www.kirt-thomsen.com/case10_airship-knarr

and here: https://projectknarr.wordpress.com/what-is-knarr/

The KNARR semi-rigid airship would be 360 meters (1,181 ft) long and would carry the wind turbine components in a large internal cargo bay. This type of airship is designed to conduct VTOL operations with a full cargo load.  When off-loading heavy cargo, this airship must take on ballast at the landing site.

The KNARR airship is a concept only.  No prototype is being built at this time.  You can view a short video defining the wind turbine transport application of KNARR airship here: https://vimeo.com/21023051

Concept drawing of a KNARR airships it lifts off after making a delivery.
Source: https://www.kirt-thomsen.com/
Concept drawing of a KNARR airship flying over a wind farm.
Source: https://www.kirt-thomsen.com/

3. Conclusions

The scale of the latest generation of wind turbines, particularly the GE LM 88.4 P, which measure 88.4 meters (290 ft) long, is approaching the limits of existing ground transportation infrastructure to handle delivery of such blades from the factory to the installation site.  GE’s introduction of two-piece blades on their new Cypress platform will significantly improve the logistics for delivering these large blades to installation sites.

Siemens’ practice of siting its wind turbine component factories with ready access to Ro-Ro shipping at an adjacent port facility greatly reduces the complexity of delivering large components to a port near an installation site.  GE has adopted the same approach with their latest factory for manufacturing the Haliad-X rotor blades in Cherbourg, France, on the English Channel.

Airships could revolutionize the transportation of large, heavy items such as wind turbine components.  However, the earliest likely candidate, the Lockheed Martin LMH-1 will not be available until the early 2020s and will  be limited to a maximum load of 23.5 tons (47,000 lb; 21,000 kg).  It seems unlikely that larger heavy-lift airships will be introduced before about 2025. 

So, in the meantime, we’ll see the largest wind turbines being installed in offshore sites.  For onshore sites, we’ll see more creative ground transportation schemes, and, probably, a broader introduction of multi-part rotor blades.

4. Recommended additional reading on wind turbines:

Energy Literacy

I was impressed in 2007 by the following chart in Scientific American, which shows where our energy in the U.S. comes from and how the energy is used in electricity generation and in four consumer sectors. One conclusion is that more than half of our energy is wasted, which is clearly shown in the bottom right corner of the chart. However, this result shouldn’t be surprising.

2007 USA energy utilizationSource: Scientific American / Jen Christiansen, using LLNL & DOE 2007 data

The waste energy primarily arises from the efficiencies of the various energy conversion cycles being used. For example, the following 2003 chart shows the relative generating efficiencies of a wide range of electric power sources. You can see in the chart that there is a big plateau at 40% efficiency for many types of thermal cycle power plants. That means that 60% of the energy they used is lost as waste heat. The latest combined cycle plants have demonstrated net efficiencies as high as 62.22% (Bouchain, France, 2016, see details in my updated 17 March 2015 post, “Efficiency in Electricity Generation”).

Comparative generation  efficiencies-Eurelectric 2003Source: Eurelectric and VGB PowerTech, July 2003

Another source of waste is line loss in electricity transmission and distribution from generators to the end-users. The U.S. Energy Information Administration (EIA) estimates that electricity transmission and distribution losses average about 6% of the electricity that is transmitted and distributed.

There is an expanded, interactive, zoomable map of U.S. energy data that goes far beyond the 2007 Scientific American chart shown above. You can access this interactive map at the following link:

http://energyliteracy.com

The interactivity in the map is impressive, and the way it’s implemented encourages exploration of the data in the map. You can drill down on individual features and you can explore particular paths in much greater detail than you could in a physical chart containing the same information. Below are two example screenshots. The first screenshot is a top-level view. As in the Scientific American chart, energy sources are on the left and final disposition as energy services or waste energy is on the right. Note that waste energy is on the top right of the interactive map.

Energy literacy map 1

The second screenshot is a more detailed view of natural gas production and utilization.

Energy literacy map 2

As reported by Lulu Chang on the digitaltrends.com website, this interactive map was created by Saul Griffith at the firm Otherlab (https://otherlab.com). You can read her post at the following link:

http://www.digitaltrends.com/home/otherlab-energy-chart/

I hope you enjoy exploring the interactive energy literacy map.

The Cargo Bicycle – An Idea Whose Time Has Come, or Has it Been Here All Along?

There has been increasing interest in the U.S. in cargo bicycles for making pickups and deliveries, particularly in inner cities with high traffic volumes and limited parking. Human or electric-powered cargo bicycles offer obvious environmental advantages over traditional, much larger gas or diesel powered delivery vehicles.

In February 2017 IKEA will be introducing a multifunctional, affordable, “city bike” called the Sladda. In addition to IKEA’s own interpretation of conventional bicycle features, the Sladda can be equipped with a variety of cargo carriers:

  • Front basket that’s rated at 10 kg (22 pounds)
  • Rear rack that’s rated at 25 kg (55 pounds)
  • Clip-on pannier (bicycle bag), which requires rear rack and converts into a backpack
  • Trailer that’s rated to haul 49 kg (108 pounds).

The rated load of the bicycle itself is 160 kg (352 pounds), including the weight of rider.

IKEA Sladda-2

Sladda configured as a cargo bicycle.  Source: IKEA

You’ll find details on the Sladda on the IKEA website at the following link:

http://www.ikea.com/us/en/

Xtracycle offer the Cargo Node and Edgerunner cargo bicycles. The folding Cargo Node, shown below, has a 159 kg (350 pound) carrying capacity, including the weight of the rider. The Edgerunner is a non-folding bicycle with a 182 kg (400 pound) carrying capacity. Both can be configured with a variety of racks. You’ll find more information at the following link:

http://www.xtracycle.com

 Xtacycle cargo bikeCargo Node.  Source: Xtracycle

Cargo bicycles may be trending in the U.S., but they have been used for many decades in Europe, particularly in Scandinavian countries, and they probably have been used just as long in Asia.

On a recent trip to China and Cambodia I found that 2- and 3-wheel cargo bicycles were very common and some were capable of carrying impressive loads. It seemed the concept of “rated load” never was an issue. Also common in China and Cambodia were 3-wheel cargo scooters and a range of small cargo vehicles that were part motorcycle and part truck. These small cargo vehicles seemed well suited for use in very high volume, relatively slow moving city traffic. Following are photos of several of the cargo bicycles, scooters and motorcycles I saw on the trip.

The cargo bicycles offered by IKEA and Xtracycle are nice, but they really don’t break new ground in the use of bicycles as cargo carriers. What is new is that individuals and businesses in the U.S. are expressing increasing interest in cargo bicycles, and other forms of small urban delivery vehicles. Next time you’re stuck in city traffic, you may be passed by a cargo bicycle in the bike lane.

Basic cargo bicycleBasic cargo bicycle in Xi’an, China

Streetsweepers cargo bikeStreet sweeper’s cargo bicycle in Xi’an, China

Cargo bike with cardboardCargo bicycle in Xi’an, China

Heavy load cargo bikeHeavy cargo bicycle in Xi’an, China

Cambodian vendor cargo bikeCargo bicycle in Cambodia

Cargo scooter beijingLoading an electric cargo scooter in Beijing, China

Cargo scooter LhasaCargo scooter in traffic in Lhasa, Tibet

cargo scooter big loadElectric cargo scooter/truck with a large volume load in Beijing, China

Cargo motorcycle tractor trailerCargo motorcycle tractor/trailer in Cambodia

Quadrennial Energy Review

On 9 January 2014 the Administration launched a “Quadrennial Energy Review” (QER) to examine “how to modernize the Nation’s energy infrastructure to promote economic competitiveness, energy security, and environmental responsibility…” You can read the Presidential Memorandum establishing the QER at the following link:

https://www.whitehouse.gov/the-press-office/2014/01/09/presidential-memorandum-establishing-quadrennial-energy-review

You can get a good overview of the goals of the QER in a brief factsheet at the following link:

https://www.whitehouse.gov/the-press-office/2015/04/21/fact-sheet-administration-announces-new-agenda-modernize-energy-infrastr

On April 21, 2015, the QER Task Force released the “first installment” of the QER report entitled “Energy Transmission, Storage, and Distribution Infrastructure.” The Task Force announcement stated:

“The first installment (QER 1.1) examines how to modernize our Nation’s energy infrastructure to promote economic competitiveness, energy security, and environmental responsibility, and is focused on energy transmission, storage, and distribution (TS&D), the networks of pipelines, wires, storage, waterways, railroads, and other facilities that form the backbone of our energy system.”

The complete QER 1.1 report or individual chapters are available at the following link:

https://energy.gov/epsa/quadrennial-energy-review-first-installment

QER 1.1 contents are listed below:

QER 1.1 contentOn January 6, 2017, the QER Task Force released the “second installment” of the QER report entitled “Transforming the Nation’s Electricity System.” The Task Force announcement stated:

“The second installment (QER 1.2) finds the electricity system is a critical and essential national asset, and it is a strategic imperative to protect and enhance the value of the electricity system through modernization and transformation. QER 1.2 analyzes trends and issues confronting the Nation’s electricity sector out to 2040, examining the entire electricity system from generation to end use, and within the context of three overarching national goals: (1) enhance economic competitiveness; (2) promote environmental responsibility; and (3) provide for the Nation’s security.

The report provides 76 recommendations that seek to enable the modernization and transformation of the electricity system. Undertaken in conjunction with state and local governments, policymakers, industry, and other stakeholders, the recommendations provide the building blocks for longer-term, planned changes and activities.”

The complete QER 1.2 report or individual chapters are available at the following link:

https://energy.gov/epsa/quadrennial-energy-review-second-installment

QER 1.2 contents are listed below:

QER 1.2 contentI hope you take time to explore the QERs. I think the Task Force has collected a great deal of actionable information in the two reports. Converting this information into concrete actions will be a matter for the next Administration.

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.

Improving Heavy Tractor-Trailer Aerodynamics

My recent road trip to the Black Hills included long transit days each way on Interstate 90 through southern Minnesota and South Dakota. One thing I noticed was that many of the heavy tractor-trailers on this high speed route had streamlined tractors and / or trailers with a variety of aerodynamic devices that appeared useful for reducing drag and fuel consumption. In addition, there were quite a few trucks hauling double trailers.

The trucking industry’s ongoing efforts to improve heavy freight vehicle performance and economics was aided in 2004 by the creation of the SmartWay Transport Partnership, which is administered by the Environmental Protection Agency (EPA). SmartWay® is a voluntarily program for achieving improved fuel efficiency and reducing the environmental impacts from freight transport. The goal is, “to move more freight, more mile, with lower emissions and less energy.”

EPA SmartWay

SmartWay® is promoting the following strategies to help the heavy trucking industry meet this goal:

  • Idle reduction
  • Speed control
  • Driver training
  • Aerodynamics
  • Tire technologies
  • Lubricants
  • Hybrid power trains
  • Improved freight logistics
  • Vehicle weight reduction
  • Intermodal freight capability
  • Alternative fuels
  • Long combination vehicles (LVCs, such as double trailers)

The SmartWay® website is at the following link:

https://www.epa.gov/smartway

You’ll find an interesting Fall 2014 presentation on the SmartWay Transport Partnership at the following link:

http://www.mmta.com/document_upload/SmartWay%20and%20Truck%20Drivers.pdf

Key points from this presentation include the following:

  • Freight transportation is a cornerstone of the U.S. economy. As of 2012, U.S. businesses spent $1 trillion to move $12 trillion worth of goods (8.5% of GDP).
  • Freight accounts for 9% of all U.S. greenhouse gas (GHG) emissions, and trucking is the dominant mode. (Note: There were about 2 million tractor-trailers in active service in the U.S. in 2011).
  • A truck or trailer fitted out with all the essential efficiency features can be sold as a SmartWay® “designated” model. A “designated” tractor-trailer combo can be as much as 20% more fuel-efficient than the comparable standard model.

In May 2012, the Canadian Center for Surface Transportation Technology (CSTT) issued technical report CSTT-HVC-TR-205, which is entitled, “Review of Aerodynamic Drag Reduction Devices for Heavy Trucks and Buses.” In Table 2 of this report, CSTT provides the following illustrative example of the relative power consumption of aerodynamic drag and rolling / accessory drag as a function of vehicle speed.

CSTT truck power consumption tableRelative contributions to total vehicle drag. Source: CSTT

In this example, rolling / accessory drag dominates at lower speeds typical of urban driving. At 50 mph (80 kph) aerodynamic drag and rolling / accessory drag are approximately equal. At higher speeds, aerodynamic drag dominates power consumption. The speed limit on I-90 in South Dakota typically is 80 mph (129 kph). At this speed the aero drag contribution is even higher than shown in the above table

Key points from this CSTT report include the following:

  • For tractor-trailers, pressure drag is the dominant component of vehicle drag, due primarily to the large surface area facing the main flow direction and the large, low-pressure wake resulting from the bluntness of the back end of the vehicle.
  • Aero-tractor models can reduce pressure drag by about 30% over the boxy classic style tractor.
  • Friction drag occurring along the sides and top of tractor-trailers makes only a small contribution to total drag (10% or less), so these areas are not strong candidates for drag-reduction technologies.
  • The gap between the tractor and the trailer has a significant effect on total drag, particularly if the gap is large. Eliminating the gap entirely could reduce total drag by about 7%.
  • Side skirts or underbody boxes prevent airflow from entering the under-trailer region. These types of aero devices could reduce drag by 10 – 15%.
  • Wind-tunnel and road tests have demonstrated that a “boat tail” with a length of 24 – 32 inches is optimal for reducing drag due to the turbulent low-pressure region behind the trailer
  • Adding a second trailer to form an LCV, and thus doubling the freight capacity, results in a very modest increase in drag coefficient (as low as about 10%) when compared to a single trailer vehicle.
  • In cold Canadian climates, the aerodynamic drag in winter can be nearly 20% greater than at standard conditions, due to the ambient air density. For highway tractor-trailers, this results in about a 10% increase in fuel consumption from drag when compared to the reference temperature, further emphasizing the importance of aerodynamic drag reduction strategies for the Canadian climate.

You can read an executive summary of this CSTT report at the following link:

https://www.tc.gc.ca/eng/programs/environment-etv-menu-eng-2939.html

You can download the complete 100-page report here:

https://www.tc.gc.ca/media/documents/programs/AERODYNAMICS_REPORT-MAY_2012.pdf

The 2012 CSTT report includes a note that Mercedes had introduced a concept trailer that is reported to provide an 18% reduction in drag for a full European tractor-trailer combination.

Mercedes-aero-trailer-4 Source: Mercedes

You can view a short 2012 YouTube video on a similar Mercedes aero tractor-trailer at the following link:

https://www.youtube.com/watch?v=I1Sq2Q8YEYw

The U.S. firm STEMCO offers two aero kits for improving conventional tractor-trailer aerodynamics:

  • TrailerTail®, which is installed at the back of the trailer, reduces the magnitude of the turbulent low-pressure area that forms behind the trailer at high speeds.
  • EcoSkirt®, which is installed under the trailer, reduces aerodynamic drag under the trailer where air hits the trailer’s rear axles. The side fairings streamline and guide the air around the sides and to the back of the trailer.

Both of these aerodynamic devices are shown in the following figure.     This was a tractor-trailer configuration that I saw frequently on I-90.

Stemco 1794Source: STEMCO

STEMCO allocates the primary sources of tractor-trailer aerodynamic drag as shown in the following figure.

Stemco contributions to semi aero dragSource: STEMCO

STEMCO claims the following benefits from their aero kits:

“TrailerTail® fuel savings complement other aerodynamic technologies. A TrailerTail® reduces aerodynamic drag by over 12% equating to over 5% fuel efficiency improvement at 65 mph (105 kph) and over 12% fuel efficiency improvement when combined with STEMCO’s side skirts and other minor trailer modifications.”

STEMCO TrailerTail® meets the SmartWay® advanced trailer end fairings criteria for a minimum of 5% fuel savings and the STEMCO EcoSkirt® meets the advanced trailer skirts qualifications with greater than 5% fuel savings. The payback period for these aero devices is expected to be about one year.

You’ll find more details on STEMCO’s tractor-trailer drag reduction products, including a short “Aerodynamics 101” video, at the following link:

http://www.stemco.com/aero-u/

More details on TrailerTail®, including its automatic deployment and operational use, are shown in a short video at the following link:

https://www.youtube.com/watch?v=qPrM3-CCth8

Another firm, Aerotech Caps, offers a range of aero kits for improving truck aerodynamics, including aerodynamic wheel covers, aerodynamic trailer skirts, tail fairings and vortex generators. You can see their product line at the following link:

http://www.aerotechcaps.com/index.html

Aero wheel covers

Source: Aerotech Caps

Aerotech Caps claims that its aerodynamic wheel covers deliver about 2.4% increased miles per gallon when installed on rear tractor and all trailer wheels. Payback period for this aero kit is expected to be about one year.

The future of heavy freight vehicles is likely to include increasingly aerodynamic tractor-trailers. One particularly elegant concept vehicle is shown below.

Future TruckjpgConcept aero-optimized heavy freight vehicle. Source: http://forums.fourtitude.com

In spite of all of these opportunities for improving heavy tractor-trailer aerodynamics, there always will be cases when few of these are actually practical. As evidence, I offer the following photo taken at 80 mph on I-90 in South Dakota during my recent road trip. How do you optimize that giant drag coefficient?

DSC_5401Source: Author photo

 

Modern Airships

This August 2016 post, which included links to 14 articles on specific historic and modern  airships, was replaced in August 2019.

“Modern Airships” now a three-part post that contains an overview of modern airship technology in Part 1 and links in Parts 1, 2 and 3 to 79 individual articles on historic and advanced airship designs. Here are the links to all three parts:

You’ll find a consolidated Table of Contents for all three parts at the following link.  This should help you navigate the large volume of material in the three posts.

I hope you’ll find the new Modern Airships series of posts to be informative, useful, and different from any other single source of information on this subject.

Best regards,

Peter Lobner

August 2019