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STEAM FLIGHT IN HISTORY

(1) STEAM AS LIFT GAS

We can be on fairly safe ground in believing that the earliest suggestion of steam as LTA lift gas was by that under-appreciated genius Sir George Cayley.

In a contribution dated 24 December, 1815 to the "Philosophical Magazine", he wrote, referring to hot-air airships:

"...by using steam in lieu of heated air for inflating the balloon, or at least a great mixture of it with the heated air. The power of steam is greater than air at the usual temperature in Montgolfier balloons in the ratio of 18 to 11, although the first inflation will cost more fuel in the ratio of 2.6 to 1. The resistance to a steam-balloon will be only as 1 to 1.38, when compared with one of the same power inflated by heated air; and hence a considerable saving of power would be the result of adopting it. But several inconveniences arise upon the introduction of steam into balloons, the chief of which are the necessity of doubling the structure, so as to suspend the steam balloon within one of heated air or gas, and of the materials being incapable of absorbing water. However, I think it very possible that the following lines of Dr. Darwin may eventually be realized:

Soon shall thy arm, unconquer'd steam! afar
Drag the slow barge or drive the rapid car;
Or on wide waving wings expanded bear
The flying chariot through the fields of air.
Fair crews triumphant, leaning from above,
Shall wave their fluttering kerchiefs as they move;
Or warrior bands alarm the gaping crowd,
And armies shrink beneath the shadowy cloud."

(Reproduction images here)

Even in 1815, Cayley's acumen had summed up in a nutshell several of the obstacles to the use of steam as lift gas. His suggestion relates to a powered airship, and naturally he was contemplating using a steam engine for propulsion, since absolutely no alternative (other than muscle power) was conceivable at the time; even electric motors hadn't yet been invented, let alone the dreaded infernal combustion engine!

Moving up to the 20th century, German Patent 214,019 (1908) proposed the use of superheated steam as lift gas for a rigid airship; the (German) text and drawings may be found here. The insulating material suggested is duck or goose down. I know of no attempt to implement this concept in practice.

The pre-eminent postwar apostle of steam lift gas was Hermann Papst, an undeservedly obscure figure. He patented several concepts relating to the subject in Germany and the USA. US Patent 3,456,903 (1969), of which the text and drawings may be found here, proposed a double walled envelope for a steam airship; Papst believed that such a double walled air-inflated structure would be very effective for insulation. US Patent 3,897,032 (1975), of which the text and drawings may be found here, relates to a method of adding heated water vapor to lift gas. And US Patent 4,032,085 (1977), of which the text and drawings may be found here, relates to an airship (which may be a steam airship) with pressurized front and rear compartments.

All of the above proposals describe (hypothetical) steam airships. Perhaps surprisingly, I have not been able to find any prior art patent literature suggesting the use of steam as lift gas for a free balloon.

However, Mr. Brian Boland of Boland Balloons has told me that some time ago he and his wife, during a stopover in Iceland enroute from the US to Europe, made an attempt to fly a balloon using steam. Geothermal steam is very plentiful in Iceland, and is used for space heating in the houses as well as for power generation. He succeeded in inflating his full-sized balloon with steam at the Blue Lagoon (a man-made hot water lake that has become a tourist attraction), but the unremitting winds unfortunately proved too violent for flight.




(2) WATER VAPOR/AIR MIXTURE AS LIFT GAS

However, the Montgolfier brothers did actually succeed (by accident rather than design) in filling the very first balloon to fly with a mixture of hot air and a minor proportion of water vapor.

They deliberately moistened the straw which they burnt for heating the air in their envelope, under the mistaken impression that the resulting smoke had some special tendency to rise. However the additional lift they obtained from the water vapor produced in this manner must have been insignificant. A description of their thought processes can be found here or here; this is a very good article.

Further, there is an ingenious type of low-tech balloon made of black plastic, filled with warmed air saturated with around 40 gm/m3 of water vapor.

As the warm air cools, the water vapor condenses upon the inside of the envelope, and these water droplets are reheated and revaporized by solar radiation, so that the air/water vapor mixture is kept warm. The French, who seem to have pioneered these balloons, term them "bulles d'orage" - meaning "storm bowls" - because their operation parallels a certain meteorological situation. With modest payloads bulles d'orage are capable of attaining quite high altitudes, of course only during the daytime. Accounts of such balloons can be found here and here and here and here. It appears that brief manned flights have even been performed - although flying hanging from a bag made from black plastic garbage bags taped together may not be everybody's cup of tea.... One has to respect the French!

(3) STEAM PROPULSION FOR AIRCRAFT

Strangely, steam has been used for propelling an LTA craft, just once, and steam has been used for propelling an HTA craft, just once (if one discounts Sir Hiram Maxim's short accidental uncontrolled flight, and certain rather apocryphal accounts of other obscure pioneers).

In 1852, Henri Giffard's dirigible was the very first navigable aircraft to fly.

Accounts can be found here and here. This craft was driven very inadequately by a 3hp steam engine. Nobody has ever subsequently propelled an airship by steam (yet!). However the idea has been used in fiction, especially comic fiction, numerous times - see a very funny and well-researched story here for example ... What is it about the conjunction of the concepts of steam and balloons that is so hilarious anyway?... I believe that "Castle Falkenstein", a well-known computer game also features the "Aerial Steam Navigation Company" and its many steam-driven airships; this type of fantasy is termed "steampunk".

The pinnacle of the steam car art was the Doble steam engine. In 1930 a chap called Besler in California converted a Doble steam engine for powering a light aircraft. This noble effort deserves to be better known; very little about it is available on the Web. A short description can be found in PDF format here and as an image here. Magazine descriptions can be found as images here and here and here and here and as text here; this last source repeats various interesting rumors of other steam aircraft being built (in 1934) in Germany and other countries, but no further information on these apocryphal efforts has come to light....

It appears that Besler only flew the plane once for about ten minutes. After all that trouble building it! Despite all the wordy camouflage, there must have been a good reason for giving up. My steam car guru's opinion is that the condensation apparatus must have been inadequate, and that the statements to the contrary are lies.

I am only aware of two other serious studies of steam power plants for aircraft. In 1926 E. E. Wilson of the US Bureau of Aeronautics wrote a 30-page report (NACA Technical Note #239), which can be seen here, describing an experimental steam generator for aircraft built by the US Navy Department. This is an extremely interesting and detailed document. The final conclusions relating to steam power for aircraft are pessimistic, mainly due to condenser weight considerations. And in 1932 the Great Lakes Aircraft Corporation proposed a steam plant for powering an airship, but no copy seems to have survived. The US Bureau of Aeronautics condemned their proposal as over-optimistic in a dismissive report (Design Memo #120), which can be seen here.



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