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More Airships from GEFA-FLUG in Germany!

by Karl Ludwig Busemeyer, GEFA-FLUG Aachen, Germany


In the first half of the last century Germany’s rigid airships introduced by “Count Zeppelin” have been world famous and still are. A regular passenger service existed between Germany and North and South America, including a world around trip in 1929 and a polar expedition in 1931. With great success the US Navy used 200 so called pressure airships for coast patrol duties until the early 60s. Since then the world has only seen a few airships, like the “Goodyear Blimps” and a few others. 

In the mid 1990s the Zeppelin company began to build medium sized airships for passenger flights. Next to that and more in the background started another “German Airship Story” which is based on a lot of “hot air” but is indeed much more than that. Mucky Busemeyer, founder of GEFA-FLUG in Aachen, has spent 35 years with airships. He designed, built and flew more different hot-air airships than anybody else. For his outstanding work he received the „Santos Dumont Airship Gold Medal“, one of the highest awards of the „Federation Aeronautique Internationale“.

The History of Hot-air Airships

Along with the general renaissance of hot-air balloons, a new type of airship made by world famous balloon designer Don Cameron entered the scene using hot air as lifting medium. Shape and stability solely depend on static hot-air pressure. Simple to build and operate they derive many features from hot-air balloons. The burner is positioned under the open belly of the envelope. Horizontal maneuverability is realized by a rudder, climb and descent by burner input. Due to a very low envelope pressure, the use of these airships is restricted to windless conditions.

At the beginning of the 80s, Thunder & Colt produced the first pressurized hot-air airship. A petrol fan maintained the envelope pressure. With high tenacity nylon fabrics the envelope pressure significantly increased. In the mid 80s Cameron brought a pressure airship on the market, too, followed by Lindstrand in 1995.

GEFA-FLUG Airships

Since the mid 70s GEFA-FLUG in Aachen has been designing airships. The first ten years were spent with development and operation of remote controlled airships. Since 1985 experiences gained with remote-controlled airships for environmental purposes led to the research of manned systems. The first twin-seater was built in 1990 using a Thunder & Colt gondola with an envelope entirely designed and built by GEFA-FLUG. This envelope type is more streamlined than existing hot-air airships and has been certified as a four-seater for passenger operation in 1999.

The general maneuverability has been improved. Pitch control is possible with the help of a V-form twin burner arrangement and the resulting heat distribution in the envelope fore and aft. Flight characteristics are considerably improved. The speed is higher due to the slimmer fineness ratio compared with traditional hot-air airships. GEFA-FLUG airships have been successfully used in more than 25 countries.

The development has been government and industry funded. The AS 105 GD is certified as a four-seater under EASA Part 21 after a five year scientific program. At the time of writing airship SN 0061 is under construction. Highlight of GEFA-FLUG’s scientific research 2005 to 2010 is the EASA certification of a six-seater hot-air airship with a volume of 5.000 m³.

Operational Characteristics:

A big advantage is carrying hot-air airships to their place of operation. Helium airships have to fly there which is very expensive depending on the distance. Hot-air airships, however, travel on the road including their three to four crew members. Only in good flying weather, hot-air airships operate with a crew of three plus pilot. Crew size of helium airships varies from 10 – 20 depending on type and size of ship. (The only exemption is the Hi-Tec Zeppelin NT with its swiveling propellers and tail thruster)

Hot-air airships are always inflated in the open field; the weather resistance is therefore lower than with helium airships. A professional crew operating an advanced hot-air airship like the AS 105 GD can stretch the wind limit up to 10/12 kts.

A simple and cheap aircraft will never have a performance as high as an expensive one. However, the efficiency might be good in both cases, as long as both do not compete in the same market niche. A four-seater hot-air airship costs 10-15% of its four-seater helium brother. It seems likely that there is a market share for both, but in different market places.


Advertising, Passenger Flights and Environmental Monitoring

The main market for hot-air airships is aerial advertising. The majority is operated by balloon companies. One can still define a hot-air airship as a powered, steerable hot-air balloon: Without engine, it can be flown like a balloon. The big advantage over the hot-air balloon is the engine and the ability to hover over a defined area.

There is a good market in visiting fairs, exhibitions, open air and sporting events, etc. in the evenings. Patrolling flights are another possible application. Hot-air airships fly over motorways and trunk roads during traffic jams in the early morning and the evening. In wintertime, hot-air airships can be operated over ski resorts and big winter games. Combined with aerial advertising, passenger flying with hot-air airships is a viable “submarket” making them even more attractive when not in use for promotional contracts.

GEFA-FLUG has proved for more then 25 years that hot-air airships are cost effective and very suitable for environmental survey projects. They take off and land vertically; they only need small launch fields which can always be found close to the flying area. This means: it is inexpensive to get them to these areas and no expensive flight time is lost in just getting there.


GEFA-FLUG: Worldwide Operational Experiences

Since the early 80s GEFA-FLUG has successfully used various hot-air airship systems in around 25 countries for various purposes. There were quite some monitoring projects all over the world like aerial photogrammetry. An early example in 1982/83 was a four month survey of a 5000 year ancient city in Pakistan. Comparable projects have been undertaken in Oman, Jemen, Syria, Greece, Turkey, Yugoslavia, Egypt, Spain, Israel and Tanzania to mention just a few. Other projects have been the documentation of the world famous castles of Neuschwanstein, or the survey of the Rhine and Danube valleys in Austria and Germany together with biologists of the “World Wide Fund for Nature” (WWF).

One highlight amongst others was “Arctic Sky ´94”, a winter expedition to the most northern point of Europe, to fly at Vadsö, the still existing airship mooring mast of the Amundsen and Nobile polar airship expeditions 1926/28. It was the first time since then that an airship had flown the Arctic skies from the European part of the planet.

Another one was „Serengeti shall never die“ to commemorate the 40
th anniversary of famous German Professor Grzimek’s flight-expedition in Tanzania in 1958, where he and his son Michael counted masses of big animals in the Serengeti National Park. The Grzimeks used a light airplane, GEFA-FLUG however the Adler airship, which proved to be an excellent stable camera platform for a TV team to monitor masses of wildebeests and zebras, without annoying them much.

In 1994 GEFA-FLUG accumulated a development budget of one million US dollars, which was partly government funded by the Ministery of Commerce. The program runs over a period of five years. The scientific part was taken over by institutes of the Technical University of Aachen. The objective was to develop a four-seater. 2005 to 2010 the research, development and certification of the six-seater airship followed.

In 2013 GEFA-FLUG produced an advanced fourseater for Bayer AG and operated it on a world tour during the 150 years celebration of Bayer AG with chief pilot Haimo Wendelstein. Sydney, New Yorl, Jobourg, Tokio, Mexico and Rio de Janeiro were the destinations in overseas. Accompanied by several cities in europe. On;; and you will find further informations and pictures / videos.


Hotair Airship AS 105 GD



Total length

134,5 ft

159,4 ft


41,3 ft

49,2 ft


3,000 m³

5,000 m³

Flight time (fully loaded)

60 min

120 min


65 hp Rotax

65 hp Rotax

Max. take-off weight

900 kg

1,488 kg

Max. flight speed approx.

22 mph

22 mph

Pilot plus Passengers



Alternative: Pilot plus “Scientific Payload”

200 kg

450 kg

Max. Payload vary on climatic conditions and flight altitude


Certified Supplementary Equipment

- Certified for VFR night flights with “Liquid Fire” to illuminate the envelope

- “AutoHeat”, automatic device for keeping a given altitude

- Electric power support to operate the side rudder


Pilot licenses

In general aviation authorities agree to fly these aircrafts with a hot-air balloon license plus a rating on hot-air airships. Depending on national regulations a minimum of 5-6 hours flying with an instructor are necessary to pass then the checkout flight. Next to that some background about engines, propellers, aerodynamics, and maintenance will be taught as well. GEFA-FLUG has established a training school at Lake Constance, the historical birthplace of the Zeppelin airships.

Addendum: This article is a short version of a much larger report with many pictures and drawings by the same author, printed in the second edition of Prof. Gabriel Khoury´s book: “Airship Technology, Cambridge University Press 2012”.