Tag Archives: DARPA

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, Boris 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 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:

5G Wireless Defined

In my 20 April 2016 post, “5G is Coming, Slowly,” I discussed the evolution of mobile communications technology and the prospects for the deployment of the next generation: 5G. The complexity of 5G service relative to current generation 4G (LTE) service is daunting because of rapidly increasing technical demands that greatly exceed LTE core capabilities. Examples of technical drivers for 5G include the population explosion in the Internet of Things (IoT), the near-term deployment of operational self-driving cars, and the rise of virtual and augmented reality mobile applications.

Progress toward 5G is steadily being made. Here’s a status update.

1. International Telecommunications Union (ITU) technical performance requirements

The ITU is responsible for international standardization of mobile communications technologies. On 23 February 2017, the ITU released a draft report containing their current consensus definition of the minimum technical performance requirements for 5G wireless (IMT-2020) radio service.

The ITU authors note:

“….the capabilities of IMT-2020 are identified, which aim to make IMT-2020 more flexible, reliable and secure than previous IMT when providing diverse services in the intended three usage scenarios, including enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine type communications (mMTC).”

This ITU’s draft technical performance requirements report is a preliminary document that is a product of the second stage of the ITU’s standardization process for 5G wireless deployment, which is illustrated below:

ITU-IMT2020 roadmap crop

Source: ITU

The draft technical performance requirements report provides technical definitions and performance specifications in each of the following categories:

  • Peak data rate
  • Peak spectral efficiency (bits per hertz of spectrum)
  • User experience data rate
  • 5th percentile user spectral efficiency
  • Average spectral efficiency
  • Area traffic capacity
  • Latency
  • Connection density
  • Energy efficiency
  • Reliability
  • Mobility
  • Mobility interruption time
  • Bandwidth

You’ll find a good overview of the ITU’s draft performance requirements in an article by Sebastian Anthony entitled, “5G Specs Announced: “20 Gbps download, 1 ms latency, 1M device per square km,” at the following link:

https://arstechnica.com/information-technology/2017/02/5g-imt-2020-specs/?utm_source=howtogeek&utm_medium=email&utm_campaign=newsletter

You can download the ITU’s draft report, entitled “DRAFT NEW REPORT ITU-R [IMT-2020 TECH PERF REQ] – Minimum requirements related to technical performance for IMT-2020 radio interface(s),” at the following link:

https://www.itu.int/md/R15-SG05-C-0040/en

In the ITU standardization process diagram, above, you can see that their final standardization documents will not be available until 2019 – 2020.

2. Industry 5G activities

Meanwhile, the wireless telecommunications industry isn’t waiting for the ITU to finalize IMT-2020 before developing and testing 5G technologies and making initial 5G deployments.

3rd Generation Partnership Project (3GPP)

In February 2017, the organization 5G Americas summarized the work by 3GPP as follows:

“As the name implies the IMT-2020 process is targeted to define requirements, accept technology proposals, evaluate the proposals and certify those that meet the IMT-2020 requirements, all by the 2020 timeframe. This however, requires that 3GPP start now on discussing technologies and system architectures that will be needed to meet the IMT-2020 requirements. 3GPP has done just that by defining a two phased 5G work program starting with study items in Rel-14 followed by two releases of normative specs spanning Rel-15 and Rel-16 with the goal being that Rel-16 includes everything needed to meet IMT-2020 requirements and that it will be completed in time for submission to the IMT-2020 process for certification.”

The 2016 3GPP timeline for development of technologies and system architectures for 5G is shown below.

3GGP roadmap 2016

Source: 3GPP / 5G Americas White Paper

Details are presented in the 3GPP / 5G Americas white paper, “Wireless Technology Evolution Towards 5G: 3GPP Releases 13 to Release 15 and Beyond,” which you can download at the following link:

http://www.5gamericas.org/files/6814/8718/2308/3GPP_Rel_13_15_Final_to_Upload_2.14.17_AB.pdf

Additional details are in a February 2017 3GPP presentation, “Status and Progress on Mobile Critical Communications Standards,” which you can download here:

http://www.3gpp.org/ftp/Information/presentations/Presentations_2017/CCE-2017-3GPP-06.pdf

In this presentation, you’ll find the following diagram that illustrates the many functional components that will be part of 5G service. The “Future IMT” in the pyramid below is the ITU’s IMT-2020.

ITU 5G functions

Source: 3GPP presentation

AT&T and Verizon plan initial deployments of 5G technology

In November 2016, AT&T and Verizon indicated that their initial deployment of 5G technologies would be in fixed wireless broadband services. In this deployment concept, a 5G wireless cell would replace IEEE 802.11 wireless or wired routers in a small coverage area (i.e., a home or office) and connect to a wired / fiber terrestrial broadband system. Verizon CEO Lowell McAdam referred to this deployment concept as “wireless fiber.” You’ll find more information on these initial 5G deployment plans in the article, “Verizon and AT&T Prepare to Bring 5G to Market,” on the IEEE Spectrum website at the following link:

http://spectrum.ieee.org/telecom/wireless/verizon-and-att-prepare-to-bring-5g-to-market

Under Verizon’s current wireless network densification efforts, additional 4G nodes are being added to better support high-traffic areas. These nodes are closely spaced (likely 500 – 1,000 meters apart) and also may be able to support early demonstrations of a commercial 5G system.

Verizon officials previously has talked about an initial launch of 5G service in 2017, but also have cautioned investors that this may not occur until 2018.

DARPA Spectrum Collaboration Challenge 2 (SC2)

In my 6 June 2016 post, I reported on SC2, which eventually could benefit 5G service by:

“…developing a new wireless paradigm of collaborative, local, real-time decision-making where radio networks will autonomously collaborate and reason about how to share the RF (radio frequency) spectrum.”

SC2 is continuing into 2019.  Fourteen teams have qualified for Phase 3 of the competition, which will culminate in the Spectrum Collaboration Challenge Championship Event, which will be held on 23 October 2019 in conjunction with the 2019 Mobile World Congress in Los Angeles, CA.  You can follow SC2 news here:

https://www.spectrumcollaborationchallenge.com/media/

If SC2 is successful and can be implemented commercially, it would enable more efficient use of the RF bandwidth assigned for use by 5G systems.

3. Conclusion

Verizon’s and AT&T’s plans for early deployment of a subset of 5G capabilities are symptomatic of an industry in which the individual players are trying hard to position themselves for a future commercial advantage as 5G moves into the mainstream of wireless communications. This commercial momentum is outpacing ITU’s schedule for completing IMT-2020. The recently released draft technical performance requirements provide a more concrete (interim) definition of 5G that should remove some uncertainty for the industry.

3 April 2019 Update:  Verizon became the first wireless carrier to deliver 5G service in the U.S.

Verizon reported that it turned on its 5G networks in parts of Chicago and Minneapolis today, becoming the first wireless carrier to deliver 5G service to customers with compatible wireless devices in selected urban areas.  Other U.S. wireless carriers, including AT&T, Sprint and T-Mobile US, have announced that they plan to start delivering 5G service later in 2019.

The Mysterious Case of the Vanishing Electronics, and More

Announced on 29 January 2013, DARPA is conducting an intriguing program known as VAPR:

“The Vanishing Programmable Resources (VAPR) program seeks electronic systems capable of physically disappearing in a controlled, triggerable manner. These transient electronics should have performance comparable to commercial-off-the-shelf electronics, but with limited device persistence that can be programmed, adjusted in real-time, triggered, and/or be sensitive to the deployment environment.

VAPR aims to enable transient electronics as a deployable technology. To achieve this goal, researchers are pursuing new concepts and capabilities to enable the materials, components, integration and manufacturing that could together realize this new class of electronics.”

VAPR has been referred to as “Snapchat for hardware”. There’s more information on the VAPR program on the DARPA website at the following link:

http://www.darpa.mil/program/vanishing-programmable-resources

Here are a few of the announced results of the VAPR program.

Disintegrating electronics

In December 2013, DARPA awarded a $2.5 million VAPR contract to the Honeywell Aerospace Microelectronics & Precision Sensors segment in Plymouth, MN for transient electronics.

In February 2014, IBM was awarded a $3.4 million VAPR contract to develop a radio-frequency based trigger to shatter a thin glass coating: “IBM plans is to utilize the property of strained glass substrates to shatter as the driving force to reduce attached CMOS chips into …. powder.” Read more at the following link:

http://www.zdnet.com/article/ibm-lands-deal-to-make-darpas-self-destructing-vapr-ware/

Also in February 2014, DARPA awarded a $2.1 million VAPR contract to PARC, a Xerox company. In September 2015, PARC demonstrated an electronic chip built on “strained” Corning Gorilla Glass that will shatter within 10 seconds when remotely triggered. The “strained” glass is susceptible to heat. On command, a resistor heats the glass, causing it to shatter and destroy the embedded electronics. This transience technology is referred to as: Disintegration Upon Stress-release Trigger, or DUST. Read more on PARC’s demonstration and see a short video at the following link:

http://spectrum.ieee.org/tech-talk/computing/hardware/us-militarys-chip-self-destructs-on-command

Disintegrating power source

In December 2013, USA Today reported that DARPA awarded a $4.7 million VAPR contract to SRI International, “to develop a transient power supply that, when triggered, becomes unobservable to the human eye.” The power source is the SPECTRE (Stressed Pillar-Engineered CMOS Technology Readied for Evanescence) silicon-air battery. Details are at the following link:

http://www.usatoday.com/story/nation/2013/12/27/vanishing-silicon-air-battery-darpa/4222327/

On 12 August 2016, the website Science Friday reported that Iowa State scientists have successfully developed a transient lithium-ion battery:

“They’ve developed the first self-destructing, lithium-ion battery capable of delivering 2.5 volts—enough to power a desktop calculator for about 15 minutes. The battery’s polyvinyl alcohol-based polymer casing dissolves in 30 minutes when dropped in water, and its nanoparticles disperse. “

You can read the complete post at:

http://www.sciencefriday.com/segments/this-battery-will-self-destruct-in-30-minutes/

ICARUS (Inbound, Controlled, Air-Releasable, Unrecoverable Systems)

On 9 October 2015, DARPA issued “a call for disappearing delivery vehicles,” which you can read at the following link:

http://www.darpa.mil/news-events/2015-10-09

In this announcement DARPA stated:

“Our partners in the VAPR program are developing a lot of structurally sound transient materials whose mechanical properties have exceeded our expectations,” said VAPR and ICARUS program manager Troy Olsson. Among the most eye-widening of these ephemeral materials so far have been small polymer panels that sublimate directly from a solid phase to a gas phase, and electronics-bearing glass strips with high-stress inner anatomies that can be readily triggered to shatter into ultra-fine particles after use. A goal of the VAPR program is electronics made of materials that can be made to vanish if they get left behind after battle, to prevent their retrieval by adversaries.”

With the progress made in VAPR, it became plausible to imagine building larger, more robust structures using these materials for an even wider array of applications. And that led to the question, ‘What sorts of things would be even more useful if they disappeared right after we used them?’”

This is how DARPA conceived the ICARUS single-use drone program described in October 2015 in Broad Area Announcement DARPA-BAA-16-03. The goal of this $8 million, 26-month DARPA program is to develop small drones with the following attributes

  • One-way, autonomous mission
  • 3 meter (9.8 feet) maximum span
  • Disintegrate in 4-hours after payload delivery, or within 30 minutes of exposure to sunlight
  • Fly a lateral distance of 150 km (93 miles) when released from an altitude of 35,000 feet (6.6 miles)
  • Navigate to and deliver various payloads up to 3 pounds (1.36 kg) within 10 meters (31 feet) of a GPS-designated target

The ICARUS mission profile is shown below.

ICARUS mission profileICARUS mission. Source: DARPA-BAA-16-03

More information on ICARUS is available on the DARPA website at:

http://www.darpa.mil/program/inbound-controlled-air-reasonable-unrecoverable-systems

On 14 June 2016, Military & Aerospace reported that two ICARUS contracts had been awarded:

  • PARC (Palo Alto, CA): $2.3 million Phase 1 + $1.9 million Phase 2 option
  • DZYNE Technologies, Inc. (Fairfax, VA): $2.9 million Phase 1 + $3.2 million Phase 2 option

You can watch a short video describing the ICARUS competition at the following link:

https://www.youtube.com/watch?v=i2U1UTDqZbQ

The firm Otherlab (https://otherlab.com) has been involved with several DARPA projects in recent years. While I haven’t seen a DARPA announcement that Otherlab is a funded ICARUS contractor, a recent post by April Glaser on the recode website indicates that the Otherlab has developed a one-way, cardboard glider capable of delivering a small cargo to a precise target.

“When transporting vaccines or other medical supplies, the more you can pack onto the drone, the more relief you can supply,” said Star Simpson, an aeronautics research engineer at Otherlab, the group that’s building the new paper drone. If you don’t haul batteries for a return trip, you can pack more onto the drone, says Simpson.

The autonomous disposable paper drone flies like a glider, meaning it has no motor on board. It does have a small computer, as well as sensors that are programed to adjust the aircraft’s control surfaces, like on its wings or rudder, that determine where the aircraft will travel and land.”

 Otherlab_SkyMachines_APSARA.0Sky machines. Source: Otherworld

Read the complete post on the Otherlab glider on the recode website at the following link:

http://www.recode.net/2017/1/12/14245816/disposable-drones-paper-darpa-save-your-life-otherlab

The future

The general utility of vanishing electronics, power sources and delivery vehicles is clear in the context of military applications. It will be interesting to watch the future development and deployment of integrated systems using these vanishing resources.

The use of autonomous, air-releasable, one-way delivery vehicles (vanishing or not) also should have civilian applications for special situations such as emergency response in hazardous or inaccessible areas.

 

 

DARPA Cyber Grand Challenge (CGC)

DARPA launched the Cyber Grand Challenge (CGC) in 2014. This is a competition in which each competitor team attempts to create an automatic IT network defense system that can analyze its own performance during attacks by an intelligent adversaries, identify security flaws, formulate patches, and deploy the patches in real-time on the network being protected. This DARPA competition will “give these groundbreaking prototypes a league of their own, allowing them to compete head-to-head to defend a network of bespoke software.”

The longer-term DARPA goal is to promote technology that leads to operational, automatic, scalable, adaptive, network defense systems operating at machine speed to protect IT networks against intelligent adversaries.

The CGC Challenge Competitor Portal is at the following link:

https://cgc.darpa.mil

The Master Schedule for CGC is shown in the following chart:

CGC Master ScheduleSource: DARPA

A slide presentation reporting the lessons learned from the first year of the CGC is available at the following link:

https://www.usenix.org/sites/default/files/conference/protected-files/sec15_slides_walker.pdf

This is a complex slide presentation that benefits greatly from seeing it along with a video of the actual presentation made by Mike Walker at the 12 – 14 August 2015 24th USENIX Security Symposium. You will find this rather long (1 hour 17 min) video at the following link:

https://www.usenix.org/node/190798

In the 2015 Challenge Qualification Event, seven finalists were qualified. The finals will be held from 54 August 2016 at the Paris Hotel & Convention Center in Las Vegas, Nevada. The Award Ceremony will be held at the beginning of DEF CON 24 on Friday, 5 August 2016.

CGCEventFirstAutomatedNetDefense  Source: DARPA

This is exciting stuff! The results are certain to be very interesting.

8 August 2016 Update: Carnegie Mellon’s Mayhem computer system won DARPA’s CGC

Seven invited teams competed for $4 million in prizes at the DARPA CGC. The $2 million grand prize winner was the Mayhem computer system designed by Carnegie Mellon’s team ForAllSecure. The $1 million second place prize was awarded to the Xandra computer system designed by team TECHx of Ithaca, NY, and Charlottesville, VV. Third place and a $750K prize was awarded to the Mechanical Phish computer system developed by the Shellphish team of Santa Barbara, CA.

You can read details on the DARPA website at the following link:

http://www.darpa.mil/news-events/2016-08-05a

Also see the following article on the TechCrunch website for more details on the CGC Finals competition.

https://techcrunch.com/2016/08/05/carnegie-mellons-mayhem-ai-takes-home-2-million-from-darpas-cyber-grand-challenge/

 

 

New DARPA Grand Challenge: Spectrum Collaboration Challenge (SC2)

On 23 March 2016, the Defense Advanced Projects Research Agency (DARPA) announced the SC2 Grand Challenge in Las Vegas at the International Wireless Communications Expo (IWCE). DARPA described this new Grand Challenge as follows:

“The primary goal of SC2 is to imbue radios with advanced machine-learning capabilities so they can collectively develop strategies that optimize use of the wireless spectrum in ways not possible with today’s intrinsically inefficient approach of pre-allocating exclusive access to designated frequencies. The challenge is expected to both take advantage of recent significant progress in the fields of artificial intelligence and machine learning and also spur new developments in those research domains, with potential applications in other fields where collaborative decision-making is critical.”

You can read the DARPA press release on the SC2 Grand Challenge at the following link:

http://www.darpa.mil/news-events/2016-03-23

SC2 is a response to the rapid growth in demand for wireless spectrum by both U.S. military and civilian users.  A DARPA representative stated, “The current practice of assigning fixed frequencies for various uses irrespective of actual, moment-to-moment demand is simply too inefficient to keep up with actual demand and threatens to undermine wireless reliability.”  The complexity of the current radio frequency allocation in the U.S. can be seen in the following chart.

image

Chart Source: U.S. Department of Commerce, National Telecommunications and Infrastructure Administration

You can download a high-resolution PDF copy of the above U.S. frequency spectrum chart at the following link:

https://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf

15 July 2016 Update: FCC allocates frequency spectrum to facilitate deploying 5G wireless technologies in the U.S.

On 14 July 2016, the Federal Communications Commission (FCC) announced:

“Today, the FCC adopted rules to identify and open up the high frequency airwaves known as millimeter wave spectrum. Building on a tried-and-true approach to spectrum policy that enabled the explosion of 4G (LTE), the rules set in motion the United States’ rapid advancement to next-generation 5G networks and technologies.

The new rules open up almost 11 GHz of spectrum for flexible use wireless broadband – 3.85 GHz of licensed spectrum and 7 GHz of unlicensed spectrum. With the adoption of these rules, the U.S. is the first country in the world to open high-band spectrum for 5G networks and technologies, creating a runway for U.S. companies to launch the technologies that will harness 5G’s fiber-fast capabilities.”

You can download an FCC fact sheet on this decision at the following link:

https://www.fcc.gov/document/rules-facilitate-next-generation-wireless-technologies

These new rules change the above frequency allocation chart by introducing terrestrial 5G systems into high frequency bands that historically have been used primarily by satellite communication systems.

Large Autonomous Vessels will Revolutionize the U.S. Navy

In this post, I will describe two large autonomous vessels that are likely to revolutionize the way the U.S. Navy operates. The first is the Sea Hunter, originally sponsored by Defense Advanced Projects Agency (DARPA), and the second is Echo Voyager developed by Boeing.

DARPA Anti-submarine warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV)

ACTUV conceptSource: DARPA

DARPA explains that the program is structured around three primary goals:

  • Demonstrate the performance potential of a surface platform conceived originally as an unmanned vessel.
    • This new design paradigm reduces constraints on conventional naval architecture elements such as layout, accessibility, crew support systems, and reserve buoyancy.
    • The objective is to produce a vessel design that exceeds state-of-the art manned vessel performance for the specified mission at a fraction of the vessel size and cost.
  •  Advance the technology for unmanned maritime system autonomous operation.
    • Enable independently deploying vessels to conduct missions spanning thousands of kilometers of range and months of duration under a sparse remote supervisory control model.
    • This includes autonomous compliance with maritime laws and conventions for safe navigation, autonomous system management for operational reliability, and autonomous interactions with an intelligent adversary.
  • Demonstrate the capability of an ACTUV vessel to use its unique sensor suite to achieve robust, continuous track of the quietest submarine targets over their entire operating envelope.

While DARPA states that ACTUV vessel is intended to detect and trail quiet diesel electric submarines, including air-independent submarines, that are rapidly proliferating among the world’s navies, that detect and track capability also should be effective against quiet nuclear submarines. The ACTUV vessel also will have capabilities to conduct counter-mine missions.

The ACTUV program is consistent with the Department of Defense (DoD) “Third Offset Strategy,” which is intended to maintain U.S. military technical supremacy over the next 20 years in the face of increasing challenges from Russia and China. An “offset strategy” identifies particular technical breakthroughs that can give the U.S. an edge over potential adversaries. In the “Third Offset Strategy”, the priority technologies include:

  • Robotics and autonomous systems: capable of assessing situations and making decisions on their own, without constant human monitoring
  • Miniaturization: enabled by taking the human being out of the weapons system
  • Big data: data fusion, with advanced, automated filtering / processing before human involvement is required.
  • Advanced manufacturing: including composite materials and additive manufacturing (3-D printing) to enable faster design / build processes and to reduce traditionally long supply chains.

You can read more about the “Third Offset Strategy” at the following link:

http://breakingdefense.com/2014/11/hagel-launches-offset-strategy-lists-key-technologies/

You also may wish to read my 19 March 2016 post on Arthur C. Clarke’s short story “Superiority.” You can decide for yourself if it relates to the “Third Offset Strategy.”

Leidos (formerly SAIC) is the prime contractor for the ACTUV technology demonstrator vessel, Sea Hunter. In August 2012, Leidos was awarded a contract valued at about $58 million to design, build, and operationally test the vessel.

In 2014, Leidos used a 32-foot (9.8 meter) surrogate vessel to demonstrate the prototype maritime autonomy system designed to control all maneuvering and mission functions of an ACTUV vessel. The first voyage of 35 nautical miles (65.8 km) was conducted in February 2014. A total of 42 days of at-sea demonstrations were conducted to validate the autonomy system.

Sea Hunter is an unarmed 145-ton full load displacement, diesel-powered, twin-screw, 132 foot (40 meters) long, trimaran that is designed to a wide range of sea conditions. It is designed to be operational up to Sea State 5 [moderate waves to 6.6 feet (2 meters) height, winds 17 – 21 knots] and to be survivable in Sea State 7 [rough weather with heavy waves up to 20 feet (6 meters) height]. The vessel is expected to have a range of about 3,850 miles (6,200 km) without maintenance or refueling and be able to deploy on missions lasting 60 – 90 days.

Sea Hunter side view cropSource: DARPA

Raytheon’s Modular Scalable Sonar System (MS3) was selected as the primary search and detection sonar for Sea Hunter. MS3 is a medium frequency sonar that is capable of active and passive search, torpedo detection and alert, and small object avoidance. In the case of Sea Hunter, the sonar array is mounted in a bulbous housing at the end of a fin that extends from the bottom of the hull; looking a bit like a modern, high-performance sailboat’s keel.

Sea Hunter will include sensor technologies to facilitate the correct identification of surface ships and other objects on the sea surface. See my 8 March 2015 post on the use of inverse synthetic aperture radar (ISAR) in such maritime surveillance applications.

During a mission, an ACTUV vessel will not be limited by its own sensor suit. The ACTUV vessel will be linked via satellite to the Navy’s worldwide data network, enabling it to be in constant contact with other resources (i.e., other ships, aircraft, and land bases) and to share data.

Sea Hunter was built at the Vigor Shipyard in Portland, Oregon. Construction price of the Sea Hunter is expected to be in the range from $22 to $23 million. The target price for subsequent vessels is $20 million.

You can view a DARPA time-lapse video of the construction and launch of Sea Hunter at the following link:

http://www.darpa.mil/attachments/ACTUVTimelapseandWalkthrough.mp4

Sea Hunter launch 1Source: DARPA

Sea Hunter lauunch 2Source: DARPA

In the above photo, you can see on the bottom of the composite hull, just forward of the propeller shafts, what appears to be a hatch. I’m just speculating, but this may be the location of a retractable sonar housing, which is shown in the first and second pictures, above.

You can get another perspective of the launch and the subsequent preliminary underway trials in the Puget Sound in the DARPA video at the following link:

http://www.darpa.mil/attachments/ACTUVTimelapseandWalkthrough.mp4

During the speed run, Sea Hunter reached a top speed of 27 knots. Following the preliminary trials, Sea Hunter was christened on 7 April 2016. Now the vessel starts an operational test phase to be conducted jointly by DARPA and the Office of Naval Research (ONR). This phase is expected to run through September 2018.

DARPA reported that it expects an ACTUV vessel to cost about $15,000 – $20,000 per day to operate. In contrast, a manned destroyer costs about $700,000 per day to operate.

The autonomous ship "Sea Hunter", developed by DARPA, is shown docked in Portland, Oregon before its christening ceremonySource: DARPA

You can find more information on the ACTUV program on the DARPA website at the following link:

http://www.darpa.mil/news-events/2016-04-07

If ACTUV is successful in demonstrating the expected search and track capabilities against quiet submarines, it will become the bane of submarine commanders anywhere in the world. Imagine the frustration of a submarine commander who is unable to break the trail of an ACTUV vessel during peacetime. During a period of conflict, an ACTUV vessel may quickly become a target for the submarine being trailed. The Navy’s future conduct of operations may depend on having lots of ACTUV vessels.

28 July 2016 update: Sea Hunter ACTUV performance testing

On 1 May 2016, Sea Hunter arrived by barge in San Diego and then started initial performance trial in local waters.

ACTUV in San Diego BaySource: U.S. Navy

You can see a video of Sea Hunter in San Diego Bay at the following link:

https://news.usni.org/2016/05/04/video-navys-unmanned-sea-hunter-arrives-in-san-diego

On 26 July 2016, Leidos reported that it had completed initial performance trials in San Diego and that the ship met or surpassed all performance objectives for speed, maneuverability, stability, seakeeping, acceleration, deceleration and fuel consumption. These tests were the first milestone in the two-year test schedule.

Leidos indicated that upcoming tests will exercise the ship’s sensors and autonomy suite with the goals of demonstrating maritime collision regulations compliance capability and proof-of-concept for different Navy missions.

4 October 2018 update:  DARPA ACTUV program completed.  Sea Hunter testing and development is being continued by the Office of Naval Research

In January 2018, DARPA completed the ACTUV program and the Sea Hunter was transferred to the Office of Naval Research (ONR), which is continuing to operate the technology demonstration vessel under its Medium Displacement Unmanned Surface Vehicle (MDUSV) program.  You can read more about the transition of the DARPA program to ONR here:
 
 
It appears that ONR is less interested in the original ACTUV mission and more interested in a general-purpose “autonomous truck” that can be configured for a variety of missions while using the basic autonomy suite demonstrated on Sea Hunter.  In December 2017, ONR awarded Leidos a contract to build the hull structure for a second autonomous vessel that is expected to be an evolutionary development of the original Sea Hunter design.  You can read more about this ONR contract award here:
 

 

Echo Voyager Unmanned Underwater Vehicle (UUV)

Echo Explorer - front quarter viewSource: BoeingEcho Explorer - top openSource: Boeing

Echo Voyager is the third in a family of UUVs developed by Boeing’s Phantom Works. The first two are:

  • Echo Ranger (circa 2002): 18 feet (5.5 meters) long, 5 tons displacement; maximum depth 10,000 feet; maximum mission duration about 28 hours
  • Echo Seeker (circa 2015): 32 feet (9.8 meter) long; maximum depth 20,000 feet; maximum mission duration about 3 days

Both Echo Ranger and Echo Seeker are battery powered and require a supporting surface vessel for launch and recovery at sea and for recharging the batteries. They successfully have demonstrated the ability to conduct a variety of autonomous underwater operations and to navigate safely around obstacles.

Echo Voyager, unveiled by Boeing in Huntington Beach, CA on 10 March 2016, is a much different UUV. It is designed to deploy from a pier, autonomously conduct long-duration, long-distance missions and return by itself to its departure point or some other designated destination. Development of Echo Voyager was self-funded by Boeing.

Echo Voyager is a 50-ton displacement, 51 foot (15.5 meters) long UUV that is capable of diving to a depth of 11,000 feet (3,352 meters). It has a range of about 6,500 nautical miles (12,038 km), and is expected to be capable of autonomous operations for three months or more. The vessel is designed to accommodate various “payload sections” that can extend the length of the vessel up to a maximum of 81 feet (24.7 meters).

You can view a Boeing video on the Echo Voyager at the following link:

https://www.youtube.com/watch?v=L9vPxC-qucw

The propulsion system is a hybrid diesel-electric rechargeable system. Batteries power the main electric motor, enabling a maximum speed is about 8 knots. Electrically powered auxiliary thrusters can be used to precisely position the vessel at slow speed. When the batteries require recharging,

The propulsion system is a hybrid diesel-electric rechargeable system. Batteries power the main electric motor, enabling a maximum speed is about 8 knots. Electrically powered auxiliary thrusters can be used to precisely position the vessel at slow speed. When the batteries require recharging, Echo Voyager will rise toward the surface, extend a folding mast as shown in the following pictures, and operate the diesel engine with the mast serving as a snorkel. The mast also contains sensors and antennae for communications and satellite navigation.

Echo Explorer - mast extendingSource: screenshot from Boeing video at link aboveEcho Explorer - snorkelingSource: screenshot from Boeing video at link above

The following image, also from the Boeing video, shows deployment of a payload onto the seabed.Echo Explorer - emplacing on seabedSource: screenshot from Boeing video at link above

Initial sea trials off the California coast were conducted in mid-2016.

Boeing currently does not have a military customer for Echo Voyager, but foresees the following missions as being well-suited for this type of UUV:

  • Surface and subsurface intelligence, surveillance, and reconnaissance (ISR)
  • ASW search and barrier patrol
  • Submarine decoy
  • Critical infrastructure protection
  • Mine countermeasures
  • Weapons platform

Boeing also expects civilian applications for Echo Voyager in offshore oil and gas, marine engineering, hydrography and other scientific research.

4 October 2018 update:  Progress in Echo Voyager development

Echo Voyager is based at a Boeing facility in Huntington Beach, CA.  In June 2018, Boeing reported that Echo Voyager had returned to sea for a second round of testing.  You can read more on Echo Voyager current status and the Navy’s plans for future large UUVs here:

http://www.latimes.com/business/la-fi-boeing-echo-voyager-20180623-story.html

Echo Voyager operating near the surface with mast extended. Source.  Boeing

DARPA Maximum Mobility & Manipulation (M3) Program is Showing Impressive New Results with the Boston Dynamics / MIT Cheetah

The two primary goals of the M3 program are:

  • Create a significantly improved scientific framework for the rapid design and fabrication of robot systems and greatly enhance robot mobility and manipulation in natural environments.
  • Significantly improve robot capabilities through fundamentally new approaches to the engineering of better design tools and fabrication methods.

More details on the M3 program are presented on the following DARPA website:

http://www.darpa.mil/our_work/dso/programs/maximum_mobility_and_manipulation_(m3).aspx

In September 2012, the DARPA / Boston Dynamics / MIT Cheetah 4-legged robot, being developed under the M3 program, reached a top speed of over 29 mph in a tethered test on a treadmill, exceeding the fastest speed ever run by a human, Usain Bolt, at 27.78 mph in a 20-meter sprint. You can see a video of this tethered test of the Cheetah at the following link:

https://www.youtube.com/watch?v=YqpO58x7vuE

In May 2015, the Cheetah demonstrated it’s ability to hurdle obstacles up to 18”tall in both tethered treadmill and untethered indoor track tests while running at an average speed of about 5 mph.

MIT-Jumping-Cheetah-1  Source: MIT

You can read the article and see a video of this test at the following link:

https://newsoffice.mit.edu/2015/cheetah-robot-lands-running-jump-0529

As described in this article:

“To get a running jump, the robot plans out its path, much like a human runner: As it detects an approaching obstacle, it estimates that object’s height and distance. The robot gauges the best position from which to jump, and adjusts its stride to land just short of the obstacle, before exerting enough force to push up and over. Based on the obstacle’s height, the robot then applies a certain amount of force to land safely, before resuming its initial pace.”

 On the treadmill, the Cheetah only had about a meter in which to detect the obstacle and then plan and execute the jump. Nonetheless, the Cheetah cleared the obstacles about 70% of the time. I can only imagine that a human runner on that same treadmill might not have performed much better. In the untethered tests on an indoor track, the Cheetah cleared the obstacles about 90% of the time. Future tests will explore the ability of the Cheetah to clear hurdles on softer terrain.

You can see more high-mobility robots being developed by Boston Dynamics at the following link:

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

These robots include:

  • Atlas: a high mobility, humanoid (bipedal) robot designed to negotiate outdoor, rough terrain. Atlas will be one of the competitors in the DARPA Robotics Challenge (DRC) Finals that will take place on 5 – 6 June 2015 at Fairplex in Pomona, California. See my 23 March 2015 post for more information on the DRC Finals.
  • LS3: a rough-terrain quadruped robot designed to go anywhere soldiers go on foot, helping carry their load.
  • PETMAN: an anthropomorphic (bipedal) robot designed for testing chemical protection clothing.
  • BigDog: a rough-terrain quadruped robot that walks, runs, climbs and carries heavy loads.
  • Sand Flea: a small robot that drives like an remote-controlled car on flat terrain, but can jump 30 ft. into the air to overcome obstacles
  • RHex: a six-legged, high mobility robot designed to climb in rock fields, mud, sand, vegetation, fallen telephone poles, railroad tracks, and up slopes and stairways.
  • RiSE: a robot that uses micro-claws to climb vertical terrain such as walls, trees and fences.
  • LittleDog: a quadruped robot designed for research on learning locomotion.