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Hot air airship made by Gefa-Flug

A thermal airship is an airship that generates buoyancy by heating air in a large chamber or envelope. The lower density of interior hot air compared to cool ambient air causes an upward force on the envelope. The most common example is the hot air balloon. An airship that uses steam would also qualify as a thermal airship.[1]

Other types of airships use a gas that is lighter than air at ambient temperature, such as helium, as a lifting gas.

Some airship designs that use a lighter-than-air lifting gas heat a portion of the gas, which is usually maintained in enclosed cells to gain additional lift. Heating the lifting gas causes expansion of the gas in order to further lower the density of the lifting gas, which results in greater lift.

Advantages and disadvantages[edit]

Thermal airships have the advantage of being much less expensive than helium-based airships. They are also routinely deflated after each flight and can be readily packed for storage and/or transport.

Hot air craft produce much less uplift per unit volume than helium- or hydrogen-filled craft (about 30% depending on air conditions). This necessitates lighter construction, with fewer controls and hence more difficulty in manoeuvring. This leads to:

  • lower airspeeds
  • difficulty in handling on the ground if the ground wind is above 5 knots
  • difficulty in steering, particularly at low airspeeds
  • lack of elevator (pitch) control, causing the airship to pitch up or down in response to changes in the throttle setting (a motion called 'porpoising').

In recent years, the steering of these ships has improved somewhat. The most successful approach has been to use higher pressure in the tail fin structures than in the rest of the envelope, or to use an internal structure (see below).


Skyacht Personal Blimp - another type of thermal airship

The first public flight of a hot air airship was made by Don Cameron (UK) in a Cameron D-96 at the Icicle Meet in January 1973. The aircraft reportedly took 3 years to develop.

Envelope structures[edit]

Most thermal airships are non-rigid. Some are pressurized. In some cases, the pressurized air is taken from a duct located behind the propeller. In other cases, the pressurized air comes from a separate fan.

In 2006, a new type of envelope employing a tensile membrane structure was developed by Skyacht Aircraft. This design uses an unpressurized envelope and an internal structure that uses ribs made of aluminium to keep the envelope in shape. When not in use, the structure folds up in a manner similar to an umbrella. The structure also permits the mounting of a steerable engine/propeller on the tail of the aircraft. The tail-mounted propeller provides for vectored thrust steering, allowing tight turns.[2]


Like hot air balloons, thermal airships are first inflated partially with cold (ambient temperature) air. Once the envelopes are sufficiently full, a propane burner is ignited and the inflation is completed using heated air.

See also[edit]


  1. ^ Steam Balloon JBFA Article
  2. ^ Youtube video of Skyacht

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Thermal_airship — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

39 news items


Fri, 12 Jun 2015 17:45:00 -0700

"Alex" is a thermal airship. It runs on hot air and it 142 feet long, nearly half the size of a football field. It's also pretty rare, so rare, few people can fly it. Barry Birch is one of them, "There's literally a handful of us, maybe less than 20 ...

Fresno Business Journal

Fresno Business Journal
Tue, 10 Feb 2015 10:11:15 -0800

The Boling thermal airship will fly over the World Ag Expo this week carrying the message: "Eat Pistachios."The Boling Air Media thermal airship is expected to make its debut over the World Ag Expo in Tulare today. Weather permitting, the agency said ...

Juneau Empire (subscription)

Juneau Empire (subscription)
Tue, 11 Jun 2013 01:26:15 -0700

Mitchell Wenkus, Video Producer for Greenpeace, photographs their thermal Airship A.E. Bates as it flies over Juneau's harbor Saturday evening to bring attention to underwater canyons in the Bering Sea. The environmental group, with it's airship ...

Fresno Bee (blog)

Fresno Bee (blog)
Fri, 14 Aug 2015 12:17:13 -0700

The proper term, said pilot Ryan Pratt, is “thermal airship.” How did I know Pratt was a pilot? Well, he was the only guy at the launch dressed in a tan jumpsuit. Kind of a dead giveaway. How did I know Ryan Pratt was a pilot? Well, he was the only guy ...


Tue, 30 Aug 2011 05:53:06 -0700

Somewhere in Boeing's Phantom Works lab there's a crinkled-up piece of paper with the heading "Boeing Hybrid Thermal Airship." It's a massive blimp with sleek and sexy lines that looks more like the body of a shark than the traditional hot dog shape.

Modesto Bee

Manteca Bulletin
Fri, 04 Sep 2015 01:26:15 -0700

What's big, yellow, half the length of a football field, weights 1,984 pounds and can fly through the air at 25 mph? It's a rare GEFA-FLUG thermal airship. And one of them will be at the Color the Skies Hot Air Balloon event at Ripon's Mistlin Sports ...

Fresno Bee

Fresno Bee
Fri, 18 Sep 2015 14:24:49 -0700

Ryan Pratt, pilot of thermal airship Bulldog, helps unfold the canopy as it's inflated. JOHN WALKER jwalker@fresnobee.com. Trevor Thompson, pilot of thermal airship Bulldog1 smiles to a crewmember before takeoff. JOHN WALKER jwalker@fresnobee.com.


Mon, 29 Aug 2011 09:27:15 -0700

Boeing considered building a gigantic, buoyant “Hybrid Thermal Airship” that would have floated as high as 30,000 feet for up to 60 days at a time and deliver cargo anywhere in the world without the need for a runway or any other infrastructure ...

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