I was lucky enough to be able to talk with Bryan Allen the other day about his experiences flying the White Dwarf and also the Gossamer aircraft. He lends a large dose of reality to those wishing and wanting to float over the trees in nearly silent, propelled, lighter-than-air vehicles.

Bryan mentions “Apparent mass” which I had to look up: Apparent Mass=Force/Acceleration. This term was used in reference to the fixed-wing Gossamer aircraft, which had large aerodynamic surfaces and low mass. Just because those airplanes weighed around 30 kg each, lifting or moving them by hand would have been hard because the force required to accelerate them (overcoming drag on their large lifting and control surfaces) would have been higher than simply “mass times gravity”. Apparent mass!

It is also quite illuminating to do as Bryan recommends, to compare cost-to-performance ratios of small powered flyers, from 0.25 up to 20 HP. At the lowest-power end of the spectrum, around that of human-power, a blimp is actually pretty competitive. Slightly increasing the size and the power, from the human’s 0.25 HP up to 1-2 HP, then fixed-winged aircraft start to get better. Afixing a 20HP to a fixed-wing aircraft can make you go 120mph (see Rutan’s Quickie), so having a blimp at that power-range is not really sensible to go from a to b.

(UNLESS you need the advertising space, need to crawl along the rainforest canopy, need to break the FAI world record for that class of airship, need to build the first “microlift airship”)

Filmed on March 21, 2010. Thanks to Aerovironment for permitting use of the image of Gossamer Albatross in the film.
Thanks most of all to Bryan Allen for the inspiring doses of reality!

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