AIRCRAFT PROPULSION — TAYLOR 247 



Odd sources of power, proposed and in some cases even tried, 

 included tethered gryphons (birds were evidently considered inade- 

 quate), sails, and horses on a treadmill (obviously at least 1,000 

 pounds per hp.). The prize for ingenuity in the unconventional 

 category might go to one Laurenco de Gusmao of Portgual, Avho, 

 about the year 1700, is said to have proposed an aircraft sustained 

 by magnets acting on electrified amber and propelled by a hand-power 

 bellows blowing on its sails. 



Sir George Cayley built and tested a "flying" machine powered by 

 gunpowder in 1807, but it never flew. A model omithopter with 

 wings operated by gunpowder, built by Trouve, is said to have risen 

 from the ground in 1870, but I consider this doubtful. 



There are records of two flights of dirigible airships using electric 

 motors with batteries, namely, that of Tissandier at Auteuil in 

 October 1883, and that of Kenard and Krebs near Paris in August 

 1884. The latter machine was considered quite successful. 



Rocket power, inspired by the Chinese invention of the ballistic 

 rocket in the 12th century, was suggested by Gerard in 1784. An 

 English cartoon of 1825 shows a proposed rocket in flight to the moon 

 propelled by a steerable steam jet. For man-carrying powered flight, 

 the first use of rockets was by Fritz von Opel (Germany) in 1928. 

 First jet-engined flight was that of the Heinkel-178 airplane in Ger- 

 many, August 27, 1939, powered with the HeS-3B gas turbine engine 

 of 1,100 pounds thrust developed by Pabst von Ohain. 



STEAM POWER 



Steam power became a popular proposal for aerial navigation in 

 the early 19th century, soon after it had been successfully demon- 

 strated in sliips, locomotives, and road vehicles. 



A model helicopter by W. H. Phillips (England) rose from the 

 ground imder steam power in 1842. Power was by steam jets in the 

 wing tips, a remarkable anticipation of a modern application of jet 

 power. 



Contrary to most historical statements, the steam-driven models of 

 Henson and Stringfellow were apparently not capable of sustained 

 rising or level flight. In the short indoor flights of record, take-off 

 was from a horizontal wire somewhat higher than the landing point. 

 Thus, these flights were what may be called "powered glides." How- 

 ever, the powerplants used are of interest because of their advanced 

 design. Gibbs-Smith attributes the powerplant design to Henson, 

 stating that Stringfellow was more the skilled mechanic than the 

 inventor. The 20-foot-span model built by Henson, but never flown, 

 was said to include a well-designed steam plant, but details are diffi- 



