History of aicraft piston engines

A ny discussion of s team power for aircraft should

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Unformatted text preview: Lack of success with this machine w as n ot t he fault of the p owerplant. A ny discussion of s team power for aircraft should include t he w ork of D r. Samuel P . L angley, Secretary of the S mithsonian Institution, w ho b uilt a nd successfully flew unmanned steampowered models 2 of 14-ft s pan in 1896. F ortunately, Langley's records a re c omplete, a nd full technical details a re a vailable. T he most notable feature of L angley's steam powerplants (fig. 7) was the use of " flash" boilers, that is, boilers consisting of one or m ore long coiled tubes with water pumped i n at one end and s team issuing from t he o ther. This type later was used successfully i n the W hite a utomobile a nd is p robably t he t ype which would b e used today if no a lternative t o s team power were available. Langley's steam plants weighed in t he n eighborhood of 7 l b/hp. H e was p erhaps t he first t o g rapple with t he problem of " flameout" in an a eronautical burner. A s entence from his m emoirs reads in p art, "Unfortunately there is a l imit t o this process [increasing t he air flow through t he b urner] of i ncreasing t he air s upply . . . a c ertain speed of efflux cannot b e exceeded without putting t he flame o ut." T he e arly j et engines encountered this same problem. Of course, steam ceased t o be of i mportance for a ircraft after flights by t he W right brothers a nd others h ad d emonstrated t he s uperior qualities of t he i nternal-combustion engine, b ut it c ontinued t o h ave a n e motional Figure 7.—Steam engine used by Samuel P. Langley in his 14-ft-span Aerodrome No. 5 (NASM 1905-1), 1896. (Photo A-12555) a ppeal to many people well into the 1930s. A Travelair biplane powered w ith a steam engine designed by William Besler was actually flown by t he designer in California in 1932. A r eplica of this engine is in the Smithsonian's National Air and Space Museum (NASM 1965-253). S team was probably given the coup de grace by Commander Eugene Wilson of the Navy Bureau of Aeronautics, a naval officer trained in s team power for ships, who reported in 1926, " On the basis of these t hree c onsiderations [weight, economy, air resistance] they [steam p owcrplants] a re absolutely impossible." My own opinion is not so extreme. If steam p ower was without competitors, we would have successful steam aircraft t oday, but at a considerable sacrifice in p erformance a nd perhaps also in safety. E arly Internal-Combustion Engines T he earliest successful aeronautical application of the internal-combustion e ngine appears to be in a dirigible-balloon flight by Paul Haenlein in G ermany in 1872. A 4-cylinder 5-hp (40 r pm) Lenoir engine using coal-gas fuel was used. The Lenoir engine was the first commercial internal-combustion engine. The cylinders drew in air for half the stroke and fired at a tmospheric pressure at midstroke. Efficiency was l ow—about 5 p ercent. T he relatively lightweight and relatively efficient "Otto-c...
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This document was uploaded on 01/19/2014.

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