248 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1962 



cult to find. Stringfellow's "flying" model was a 10-foot-span mono- 

 plane equipped with a %-inch bore by 2-inch stroke double-acting 

 steam engine driving two mid- wing 16-inch propellers geared to three 

 times engine speed. Its best powered glide was for about 120 feet 

 indoors. A Stringf ellow engine and boiler, a multibulb affair, is now 

 at the National Air Museum of the Smithsonian Institution (pi. 1, 

 fig. 1). 



A dirigible balloon with a 3-hp. steam plant weighing 351 pounds 

 was flown by Henri Giffard from Paris to Trappes in 1851 (pi. 1, fig. 

 2.) I have not found a technical description of this engine. In spite 

 of earlier and later designs for steam-driven dirigible balloons, that 

 of Giffard seems to be the only one which made successful flights. 



Mozhaiski in Eussia in 1884 and Clement Ader in 1890 both built 

 and tested full-scale steam-powered machines. At most, these ma- 

 chines made short uncontrolled "hops." Only Ader's machine seems 

 to have had the ability to lift itself without external assistance. No 

 engine details seem to be available. 



The best-known full-scale attempt at flight with steam was that of 

 Sir Hiram Maxim in 1893. Maxim was an experienced steam en- 

 gineer, and his powerplant was far more advanced than the aircraft 

 to which it applied. It was rated at 363 hp. and weighed, complete, 

 1,800 pounds or 5 pounds per hp. The engine, a two-cylinder affair 

 (pi. 2, fig. 1), was evidently of extraordinarily light weight. The 

 boiler (pi. 2, fig. 2) was of the multiple water-tube type, very much 

 like modem marine steam boilers. Operation along rails indicated 

 that this engine could furnish the power necessary to lift even the 

 monstrous contraption in which it was installed. Lack of success with 

 this machine was not the fault of the poweq^lant. 



Any discussion of steam power for aircraft should include the 

 work of S. P. Langley who built and successfully flew an unmanned 

 steam-powered model of 14-foot span in 1896. Fortunately, Langley's 

 records are complete, and full technical details are available. The 

 most notable feature of Langley's steam powerplants (pi. 3, fig. 1) 

 was the use of "flash" boilers, that is, boilers consisting of one or more 

 long coiled tubes, with water pumped in at one end and steam issuing 

 from the other. This type was used successfully later in the White 

 automobile and is probably the type which would be used today if no 

 alternative to steam power was available. Langley's steam plants 

 weighed in the neighborhood of 7 pounds per horsepower. He was 

 perhaps the first to grapple with the problem of flame "blowout" in 

 an aeronautical burner. A sentence from his memoirs reads in part, 

 "Unfortunately there is a limit to this process (increasing the air flow 

 through the burner) of increasing the air supply ... a certain speed 



