Cameron Balloons had been producing hot air balloons for five years when they designed the world's first hot air airship or thermal airship. This, the D-96, has much in common with the balloons, being a non-rigid airship, covered in a nylon fabric and with a propane burner to feed hot air into the envelope from a gondola suspended below it. However, it has the elongated body shape of conventional helium and hydrogen filled airships, airscrew propulsion and stabilizing tailfins. With a length to minimum diameter ratio of only about 2.5, the envelope is fatter than that of many airships. The D-96 is powered a 1.6 L Volkswagen engine, modified to run onpropane so that engine and burner use the same fuel. Mounted at the rear of the gondola, this drives a large diameter, partly shrouded propeller. This gondola carries propane fuel and a double burner, the pilot and up to two passengers. Hot air is guided into the envelope by a small, funnel-like extension above the burners. On 4 January 1973Don Cameron and Teddy Hall demonstrated the first D-96, registration G-BAMK, at the Icicle meeting at Newbury, Berkshire. Some records state that this first flight was made on 7 January or over the weekend of 6–7 January. After some initial testing, Cameron's attention returned to balloon manufacture but interest in the airship was revived in 1976 by an order from the U.S.A. The early flights had revealed some directional stability problems, addressed by progressively increasing the number of tailfins. The instabilities were finally cured by a four-finned, cruciform arrangement, with the fins inflated by air from the propeller slipstream, fed from an intake with a tongue-like scoop through a passage along the keel. A rudder, operated from the gondola by cable, was added to the lower fin. At the same time the gondola suspension was improved so that it no longer distorted the envelope. Originally the D-96 had an envelope capacity of 96,000 cu ft, as indicated by its name, but during 1978 the envelope was lengthened, increasing the volume by about 7%. This new envelope was used on subsequent production D-96s.
Operational history
16 D-96s had been built by January 1984 for customers across Europe, in Australia, Canada, U.S.A and Japan; of these, eight appeared on the UKcivil aircraft register, though they are all deregistered in 2012. One of these is now on the 2010 French register; another D-96, not previously on the UK register is registered in Spain.
