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Aviation History
1942
1942 - 1587.PDF
JULY 30TH, 1942 FLIGHT "7 430 deg. C. The condenser worked at atmospheric pres sure. The weight per power-unit was about 4.5 kg./h.p. Jv (whereof 0.95 kg. was the propelling machinery, 1.1 kg. the water-tube boiler, and 2.75 kg. the condenser and the auxiliaries). The airscrew was driven direct by the reciprocating steam engine at 1,350 r.p.m. A later version embodied a reciprocating steam engine based on the design described above with a weight of 180 lb. The power developed was 150 h.p. at 1,625 r.p.m. supplied with steam at 1,200 lb./sq, in. pressure. The steam generator consisted of a single tube about 500ft. in length, and weighed with accessories 150 lb. Fired by- oil fuel it could be heated up to working pressure within 40 to 60 sec. To start the generator it was only necessary to switch on an electrically activated blower, which mixed the air and fuel in the correct proportion and forced it through a special burner into the combustion chamber, where byt means of a sparking plug the mixture ignited. From this moment steam pressure and temperature were automatically controlled by a thermostat, and the pilot had merely to regulate output by.means of a throttle in the air intake. Swiss and American Types 4ajt The Sulzer Single Tube Steam Generator, constructed Pby the Gebr. Sulzer of Winterthur, Switzerland, 1933, was composed of a tube 40 mm. diameter, 1,300 m. length, and worked under pressure of 100 atmospheres. Feed water entered at 150 deg. C. and at 130 atmospheres, and after super-heating left at 400 deg. C. and 100 atmo spheres. The pressure drop along the tube ensured active circulation and high heat transfer. Over 7,000 kg. of water were evaporated per hour, giving a steam output of 24 kg./hr./sq. m. of heating surface. (Stodola.) The Great Lakes Aircraft Corporation of America collaborated with the General Electric Company in the development of steam-propelling plants intended for installation in large flying boats. The result of this development was a steam power unit of 2,300 h.p. with a La Mout type steam boiler. The main components of the generator were: an air pre-heater, a blower to assist the action of the relative wind, a super-heater, an oil burner and an exhaust mani fold. Wet and superheated steam was carried in steel-alloy pipes lining the walls of the generator, arranged axially and forming to- 4| .ether a cylindrical-shaped casing. Vipes for oil and water were in light alloy. The boiler was started electrically and produced a maxi mum of 9.5 tons steam per hour at a temperature of 540 deg. C. and a pressure of 70 atm. The blower for the combustion air was activated by means of electro motors fed from a storage battery. The operational altitude of this power plant was 1.5 km., and the specific fuel consumption was re ported to be 270 gr./h.p., showing a thermal efficiency of 23 per cent. Aero Turbines, Ltd. Some time in 1938 this firm demonstrated a prime mover, closely resembling the German Huttner turbine, in which the rotary generator, turbine, con denser and starting mechanism were combined in a single unit. \he general principle is simple enough: It includes a boiler of the rotary type, with U-tubes IGNITION ELEMENT U TUBE TURBINE WHEEL FEED WATER PUMP COMBUSTION CHAMBER The steam power plant of Aero Turbines Ltd. : (I) Ignition Plug, (2) Insulating Wali, (3) Atomizer, (4) Path of Fiame, (5) Path of Steam, (6) Centrifugal Pump, (7) Reaction Plate, (8) Water Inlet and throuph A & B, (9) Annular Chamber and U-tubes integral with Reaction Plate and rotating in same direction, (10) Spent Stf am to Condenser, (n) Burnt Exhaust Gases. A section through the steam unit of the Aero-Turbines Ltd. having their open ends connected with the water pump and steam passage to the turbine respectively. The tur bine is within the same casing, and when the turbine has once been started rotating by a small extraneous electric motor and has generated a certain amount of steam, it is self-driven by the reaction of the steam jets. The two rotate in opposite directions, and a small rotary pump feeds the water to the boiler. Fuel oil of almost any sort can be used, and a com bustible mixture is passed through a series of holes in an annular mixing chamber into the combustion chamber, in which it is ignited by an electrically heated wire. In tests demonstrating the effi ciency of the power plant, cold water was fed to the boiler, and in about 65 seconds the steam gauge indicated 25 lb./sq. in. The fuel was turned off and cold water was fed to the boiler with no disastrous results. Then the fuel was turned on and the boiler started again. The particular boiler, it might be mentioned, was capable of an output of approximately 30 h.p. Boiler Speeds According to the constructor's report the rotary boiler can be used as a condenser. During the development period a boiler was, according to these reports, run at various speeds up to a peripheral speed of 830 ft./sec. and provided pressures up to a maximum of 150 atmospheres. The maximum heat transmission capacity at maximum velocity was 553.000 B.Th.U./sq. ft./hr. When the same unit was run as a con denser at the same maximum speed, the maximum heat trans mission was found to be 203,000 B.Th.U./sq. ft./hr. In a 2,000 h.p. unit the turbine is reported to run at about 10,000 r.p.m. and the boiler at something like half that speed.—Reported fuel consump tion, 0.35 lb./b.h.p./hr. Unit weight, 2 lb./h.p.
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