Pratt & Whitney R-985
| Pratt & Whitney | |
|---|---|
 Pratt & Whitney R-985 AN-1 radial engine in a Boeing Stearman |
|
| R-985 Wasp Junior | |
| Production period: | 1930-1953 |
| Manufacturer: | Pratt & Whitney |
| Working principle: | Otto |
| Motor design: | Nine-cylinder star engine |
| Valve control: | OHV |
| Displacement: | 16,100 cm 3 |
| Mixture preparation: | |
| Engine charging: | compressor |
| Cooling system: | air |
| Lubrication system: | Dry sump |
| Power: | 220 kW |
| Previous model: | none |
| Successor: | none |
The Pratt & Whitney R-985 Wasp Junior is an air-cooled aircraft engine from the US manufacturer Pratt & Whitney . With a displacement of 985 cubic inches (approx. 16 liters) it is the smallest of the P & W “Wasp” engine family. The nine-cylinder - radial engine was (from 1930 in civil and military aircraft and helicopters later in -H5 Sikorsky ) used. Production ended in 1953 after 39,037 engines had been delivered.
construction and development
The Wasp Junior was developed as a smaller variant of the R-1340 Wasp in order to be represented in the market for medium-sized aircraft engines. Like its larger counterpart, the Wasp Junior is an air-cooled nine-cylinder Otto radial engine with a gear-driven centrifugal compressor . Its cylinders have a displacement of around 27% smaller than the R-1340. This was achieved by reducing the bore and stroke to just 131.76 mm (5.1875 inches). The Wasp Junior shares many of its components with the Wasp and has the same installation dimensions, so that these motors can be interchanged with one another. After the first test runs in 1929, sales began in 1930. The original Wasp Junior A series developed 220 kW (300 hp).
The US military classified the Wasp Junior as R-985. Different suffixes indicate these different military variants. However, this system was not adopted by Pratt & Whitney, so that civilian models can be distinguished from military variants based on their model name.
The Wasp Junior A was replaced by more powerful models, the later B series . They are more highly compressed, have higher top speeds and more effective charging. The first B-model was the Wasp Junior TB , which delivers a nominal power of 310 kW (420 hp) at sea level and has a starting power of 330 kW (440 hp). The TB was optimized for top performance at sea level, followed by the Wasp Junior SB , which was designed for high altitude flight. The SB delivers 300 kW (400 hp) to an altitude of 5000 feet and has a take-off power of 340 kW (450 hp). An improved variant of the SB was the Wasp Junior T1B2 , which is characterized by improved performance at low altitudes. Up to an altitude of 450 m, its output is 340 kW (450 hp), while its performance data for high-altitude flight at 1500 m match that of the SB. The SB and T1B2, along with their similarly powerful successors, were the most popular Wasp Juniors. A special form of the T1B2, the Wasp Junior B4, is designed for vertical installation in helicopters.
In the mid-1930s, Pratt & Whitney again developed a revised series of the Wasp Juniors, the C series , which was even more compressed and should have an even higher top speed than the B series. Only one C-series model was built, the Wasp Junior SC-G . This engine developed 390 kW (525 hp) at an altitude of 2,900 m and had a take-off power of 450 kW (600 hp). The suffix -G stems from the fact that the SC-G a decimation g etriebe has thus could be achieved with the higher motor rotating an effective propeller speed. This engine was built into a D-17W Beechcraft Staggerwing , but did not get beyond the prototype stage.
Use (selection)
- Airspeed Oxford
- Avro Anson
- Barkley-Grow T8P-1
- Beechcraft Staggerwing
- Beechcraft Model 18
- de Havilland DHC-2 "Beaver"
- Lockheed Electra
- Lockheed Electra Junior
- Max Holste Broussard
- Vought Kingfisher
- Pitts Samson
- Howard DGA
- Boeing Stearman
- Stinson V-77 Gullwing
- Junkers F 13 (in a Rimowa replica)
Technical specifications
- Wasp Junior
- Bore : 131.76 mm (5 3 ⁄ 16 in )
- Stroke : 131.76 mm (5 3 ⁄ 16 in )
- Displacement : 16,141 cm 3 (985 in 3 )
- Length: 1,056 mm (41.59 in)
- Diameter: 1,162 mm (41.59 in)
- Valve control: OHV, 18 valves
- Charging: General Electric centrifugal charger
| model | Continuous output | Maximum benefit | Starting power | Compression ratio | Loader gear ratio | min. Octane number | Dry matter |
|---|---|---|---|---|---|---|---|
| Wasp Junior A | 220 kW at 2000 min -1 | Sea level | identical to continuous output | 5: 1 | 7: 1 | 68 | 256 kg |
| Wasp Junior TB | 310 kW at 2200 min -1 | Sea level | 330 kW at 2300 min -1 | 6: 1 | 8: 1 | 80 | 290 kg |
| Wasp Junior SB | 300 kW at 2200 min -1 | 1,500 m | 340 kW at 2,300 rpm -1 | 6: 1 | 10: 1 | 80/87 | 290 kg |
| Wasp Junior T1B2 | 340 kW at 2,300 rpm -1 | 450 m | identical to continuous output | 6: 1 | 10: 1 | 80/87 | 296 kg |
| Wasp Junior B4 | 340 kW at 2,300 rpm -1 | 700 m | identical to continuous output | 6: 1 | 10: 1 | 80/87 | 310 kg |
| Wasp Junior SC-G | 390 kW at 2700 min -1 | 2900 m | 450 kW at 2,850 min -1 | 6.7: 1 | 10: 1 | 100 | 392 kg |
See also
Web links
Individual evidence
- ↑ The 'Wasp Junior'. (PDF) In: Flight. January 10, 1930, pp. 101-102 , accessed February 2, 2017 .
- ^ Pratt & Whitney - R-985 Wasp Jr. Pratt & Whitney , archived from the original on February 10, 2010 ; accessed on February 2, 2017 .
- ^ A b c d Pratt & Whitney (1956), p. A2
- ↑ a b FAA Type Certificate Data Sheet ATC 39
- ↑ a b FAA Type Certificate Data Sheet TC 85
- ↑ a b c d e f FAA Type Certificate Data Sheet E-123
- ↑ FAA Type Certificate Data Sheet TC 5E-1, see 5 and 6.
- ^ A b c Pratt & Whitney (1956), p. A3
literature
- Gunston, Bill: World Encyclopedia of Aero Engines . Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
- Pratt & Whitney: Index of Wasp Jr. & R-985 Designated Engines , 1956.
- Цыгулев (Zigulew): Авиационные моторы военных воздушных сил иностранных государств ( German aircraft engines of the military air forces of foreign countries ) . Ed .: Государственное военное издательство Наркомата Обороны Союза ССР. Moscow 1939 (Russian, online - Ed. State Military Publishing House of the People's Commissariat for Defense of the USSR).
- Wasp Jr. A: Type Certificate Data Sheet ATC 39.Retrieved December 12, 2009 .
- Wasp Jr. SB, T1B2, B4: Type Certificate Data Sheet E-123. Retrieved December 12, 2009 .
- Wasp Jr. TB: Type Certificate Data Sheet TC 85.Retrieved January 7, 2010 .
- Wasp Jr. military models: Type Certificate Data Sheet TC 5E-1. Retrieved January 7, 2010 .