What about some sort of hand cranked propellor for dirigibles?
I'm surprised no one has referenced the White Dwarf human-powered airship yet! See also
White Dwarf
and Pedal–Powered
Flight
BRYAN L. ALLEN
Note that's a PDF. But it's by...well I'll let the intro blurb to this article do the talking...
Bryan L. Allen first learned to fly in 1974 In a foot–launched
hang glider. He was the pilot of the Gossamer Condor pedal–
powered airplane that won the £50,000 Kremer Prize in 1977.
The Condor is now on permanent display at the National Air
and Space Museum in Washington, DC. In 1979, he piloted the
Gossamer Albatross across the English Channel to win the
Kremer Cross–Channel Prize of œ100,000 for the group
headed by Dr. Paul MacCready. in 1984, ha set a speed record
at 23.5 mph when piloting the MacCready Bionic Bat, winning
the fourth installment of the Kremer World speed contest for
stored–energy human–powered aircraft. He still holds two
Federal Aeronautique international world records: distance
and duration for Class BA–1 through BA–l0 (nonrigid gas
airships). All told, he has piloted eight different human powered
aircraft. Bryan is employed full time by Telos Corporation, a
software services company, at the Jet Propulsion laboratory In
Pasadena, California. He possesses private pilot ratings for
airplane single–engine land and gliders and Is looking
forward to some day having an airship rating.
So it's hard to imagine who would be more qualified to participate in this discussion in general, for either HTA or LTA!
{edit}--of course the White Dwarf, and any sensible human-powered design, is not arm-cranked but leg-pedaled.{/edit}
Now some strong caveats--despite its steampunk look, White Dwarf is very much late 20th century technology. (Reed Gleason, who later acquired it, added a "weedwhacker" with a propeller on the tip to boost its propulsion, because human pedaling is both tiring and risky once one gets exhausted, so it didn't stay strictly human powered at that!) The "fabric" is a plastic sheeting material developed for utility tethered balloons, far advanced over anything possible in the 19th century. The gondola frame is made of modern metals, the prop and fin are styrofoam.
Trying to match the strength-weight ratios of these materials with what's available pre-1900 would be impossible. Maybe bamboo could get you a comparable gondola weight?
Note the speed ranges in Allen's article--a really hard pedaling effort can get it up to maybe 12 mph. (And the aerodynamic instability of the hull overcomes pendulum stability around 15 mph, something the designer did not worry about given the superhuman strength required to approach such an airspeed). Allen figures a sustainable "cruise" speed of about 7-8 mph.
The trouble with very slow airships is, one has to have enough speed to assert some navigational authority despite contrary winds. Airships capable of 40-50 knots often find themselves stuck; even the big Naval rigid airships Akron and Macon with their 70 knot airspeed capability found themselves trapped from time to time. At 7 knots, one has a moderately directable free balloon.
Can a pre-19th century gasbag, made of varnished silk most likely, or rubberized silk perhaps, come close to the lightness of the White Dwarf's skin? How about its gas-retaining properties? It sort of helps that helium would be unavailable, so perforce they'd use hydrogen. Or other mixes common in OTL early LTA experimentation, like "town gas" which is a mix of hydrogen and carbon monoxide
Hydrogen is easier to retain than helium, but not by a whole lot--it's still a slippery, leaky gas.
I don't think anyone in a European setting paralleling our time line would divert themselves into trying for a human-powered dirigible; by the time they have the availability of hydrogen, suitable materials for the gas bag and frame, and some clue of aerodynamics for the design, they will have mechanical (including electrical--the more successful 19th century airships were often battery-powered) power plants that are ludicrously inadequate by the standards of the age of flight proper but still better than human power!
Before abandoning the line of thought completely though, one might reflect on what might happen if we scale the ship up from a one-person to a multi-person capability. If we were to double the linear dimensions, we'd get eight times the lift volume, whereas the drag area would only be multiplied by four, meaning if all eight people were to pedal together, we'd have twice the power per drag area available. This only works out something like a 20-25 percent speed increase, allowing cruise at perhaps 10 mph if everyone stays pedaling, alternatively the crew can alternate, with half of them pedaling and half resting, so the effort can be sustained perhaps indefinitely--assuming our lift budget includes a fair amount of food and water!
Even bigger scaling slowly increases the speed margin. Meanwhile, scaling up an airship at a given state of the art tends to involve heavier structures; the drag area proportion goes down (so less "engine" or in this case our pathetic human "engine" is more effective), the structural strength against aerodynamic bending requirement scales in proportion to volume and hence mass--but the structural aspect of achieving suspension of the weight of the craft rises. Also, as we achieve higher speeds, the bending stress on the hull increases as the square of the speed, leading either to risk of failure or increased hull weight. And there is the aforementioned dynamic instability at higher speeds, which was not a problem at 10 mph but would be at 15.
The idea of an air galley, propelled by hundreds of pedallers, seems quite romantic--I was thinking air Vikings. But even a ship that could lift half a thousand of them couldn't go much more than 20 knots, leaving them too much at the mercy of winds. And where, before 19th century type tech is available, is anyone going to get hydrogen? (With inferior lift gases, like say steam, or town gas, or methane, or ammonia, the performance is more marginal still, and there are risks and dangers that even hydrogen doesn't pose).
Hydrogen by the way, assuming someone figures out how to make it in quantity, is less risky for a human powered vehicle than for one powered by an engine that burns fuel, or by electric motors whose power lines might produce sparks. Until, that is, the humans driving it get hungry and want cooked food!
Perhaps horses can be harnessed somehow to drive a big bio-powered airship--I'm not sure hayburners are really much more efficient than human muscle, pound per pound. Actually DValdron in the Thule thread came up with some interesting figures that suggest that horses aren't such great draft animals, pound per pound, compared to dogs! But I don't see how one harnesses a lot of dogs to be propulsion units, and their food stock of meat would tend to spoil a lot faster than hay.
Meanwhile even if the horses or dogs actually propelling the ship don't need cooked food, the humans aboard would still want it. And there's the kaboom!
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