Back to the future: airships and the revolution in strategic airlift: over the next several years the US Department of Defense has some very hard decisions to make regarding strategic airlift. If funding is not available to meet 54.5 MTM/D or more with conventional airlift, either sacrifices in capability must be made or an alternative will have to be found

Air Force Journal of Logistics, Fall-Winter, 2005 by Walter O. Gordon, Chuck Holland

Back to the Future: Airships and the Coming Revolution in Strategic Airlift

The last major study of US airlift requirements, Mobility Requirements Study 2005, concluded the United States requires an airlift fleet capable of transporting 54.5 million ton-miles per day. Recent developments indicate the requirement will be even higher, perhaps up to 60 MTM/D. According to General John Handy, commander of AMC and USTRANSCOM, even meeting the lower requirement requires a C-17 fleet of 222 aircraft, 42 more than the 180 currently under contract. This article proposes an alternative aircraft, a hybrid aircraft, half airship/half airplane, which would cost about the same as a C-17 to acquire but would potentially be three times as productive and cost one-half to one-third as much to operate per ton-mile.

The Requirement

The last major study of US airlift requirements, Mobility Requirements Study 2005 concluded the United States requires an airlift fleet capable of transporting 54.5 million ton-miles per day (MTM/D). Recent developments indicate the requirement will be even higher, perhaps up to 60 MTM/D. According to General John Handy, commander of Air Mobility Command (AMC) and Transportation Command, even meeting the lower requirement requires a C-17 fleet of 222 aircraft, 42 more than the 180 currently under contract. (1) With the Air Force fighting the possible cancellation of the C-130J as well as a significant cutback in the number of F/A-22s, the purchase of 52 more C-17s seems unlikely, much less the number required to meet 60 MTM/D.

Is the C-17 the best way to overcome the airlift shortfall? This article proposes an alternative aircraft--a hybrid aircraft, costing about the same as a C-17, but potentially three times as productive and costing one-half to one-third as much to operate per ton-mile.

An airship obviously has significantly different operating characteristics than an aircraft. Some operating characteristics are better, some are not, and some are just different. Those characteristics will be discussed in this article, but the bottom line is that an airship is probably a viable and affordable alternative to buying additional C-17s and should be considered for filling the airlift gap.

Airship 101-A Brief History

The Flight of the Luftschiff Zeppelin 59

In 1917 a German aircraft departed Bulgaria on a 3,600 nautical-mile flight carrying 30,000 pounds of medical supplies and ammunition for a beleaguered army unit in Africa. When it landed 95 hours later it still had 64 hours of fuel remaining--enough to have flown to San Francisco bad it taken a great circle route west instead of flying south. Nonstop flights from Bulgaria to San Francisco carrying that large a payload could not have been accomplished by a B-29 thirty years later. In 1917, it was closer to the realm of science fiction. (2)

What type of aircraft was this and how was it possible in 1917? It was the German Luftschiff Zeppelin 59 (LZ 59), a rigid airship. During the flight most of the weight of the ship was held aloft by buoyant lift, the difference in weight between the air displaced by its gas envelope and the hydrogen contained within. As a result, all the engines of the Zeppelin had to do was overcome the drag of the vessel as it passed through the air. The engines on a conventional aircraft must do that as well, but must also overcome the additional drag from the wings lifting the weight of the aircraft.

Graf Zeppelin

Twelve years later, in August 1929, the German airship Graf Zeppelin flew around the world in four stops carrying twenty passengers and forty-one crew. The longest leg was a nonstop flight between Friedrichshafen, Germany and Tokyo, a distance of over 7,000 miles covered in 100 hours. Not only was a flight like this unthinkable by an airplane in 1929, the passengers made the flight in accommodations unavailable to the commercial air traveler even today (see Figure 1).

[FIGURE 1 OMITTED]

The spacious dining room of the Graf Zeppelin makes another point about airships. Because the gas envelope is necessarily many times larger than the fuselage of an airplane of comparable gross weight, they tend to have much more volume available for passengers and cargo. It is much more difficult to bulk-out an airship than an aircraft.

US Navy Airship Operations

From 1923 to 1935 the US Navy operated a total of four rigid airships, Shenandoah, Los Angeles, Akron, and Macon. The loss of three of them to accidents--only Los Angeles retired without mishap--coupled with the loss of the Hindenburg several years later, sounded the death knell for large airship operations. Looking at the losses of the individual ships, however, one sees that it was not as bad as a simple 75 percent hull loss rate might indicate.

Shenandoah flew 740 hours before being lost in a severe thunderstorm. Los Angeles retired with 4,181 hours. Akron crashed at sea in a storm due to a faulty altimeter setting with 1,695 hours, and Macon ditched at sea with 1,798 hours after her vertical stabilizer was ripped off by clear air turbulence. (3)