| 词条 | Pratt & Whitney R-1860 Hornet B | ||||||||||||||
| 释义 |
The Pratt & Whitney R-1860 Hornet B was a relatively uncommon aircraft engine. It was a development of Pratt & Whitney's earlier R-1690 Hornet and was basically similar, but enlarged in capacity from 1,690 to {{convert|1860|cuin|litre}}.[1][2] Cylinder bore was increased by 1/8" and the crankshaft stroke by 3/8". Both engines were air-cooled radial engines, with a single row of nine cylinders. Design and developmentThe cylinder and valve design was typical for Pratt & Whitney, a simple design with two large valves driven by pushrods. The enlarged engine was designed by George Willgoos and was first available in 1929.[3] The Hornet series of engines was similar to the Wasp, but larger. In both series a nine-cylinder single-row engine was later supplemented by an enlarged fourteen cylinder engine, with two rows of the same cylinders, but reduced in number to seven per row to aid cooling to the rear row (it was never made into a larger, 18 cylinder radial like the related Wasp was). Two of these engines, the enlarged single-row Hornet B described here and the R-1830 Twin Wasp, were of near-identical displacement (1860 vs. 1830), although the fourteen-cylinder Twin Wasp was more complex and costly than the nine-cylinder, single-row Hornet B. The Twin Wasp was by far the more powerful engine though, even in its early versions it produced 800 bhp to the Hornet B's 575 bhp. Having more cylinders per the same displacement also creates a smoother engine, since the individual pistons are smaller and lighter, and the stroke is shorter, which reduces the vibration of reciprocation, and therefore crew and mechanical fatigue. The reduced stroke also allows for a higher maximum RPM limit, since the mean piston speed is reduced, the distance the piston has to cover per each engine revolution being shorter. Having a shorter stroke but a higher rpm limit for the same displacement reduces the peak torque levels, but allows for a higher maximum horsepower rating. A further advantage was the reduced diameter of the Wasp: 48 inches compared to 57. This reduced drag, and the relatively large diameter of the Hornet would also have been a serious drawback for visibility if used in a small single-engined aircraft. Although a technically competent design, the enlarged Hornet B engine was not a commercial success. Customers preferred to buy the R-1830 Twin Wasp instead, which in time became the most numerous aircraft engine ever produced. Applications
Specifications{{pistonspecs||ref={{cite web |title=Pratt & Whitney Hornet R-1860-B |url=http://nasm.si.edu/collections/artifact.cfm?id=A19660390000 |publisher= Smithsonian National Air and Space Museum |ref=Smithsonian }} and Aircraft Piston Engines by Herschel Smith |type=Nine-cylinder single-row supercharged air-cooled radial engine |bore=6.25 in. (158.8 mm) |stroke=6.75 in. (171.4 mm) |displacement=1864 cuin (30.54 L) |length=113.7 cm (44.78 in.) |diameter= 144.6 cm (56.93 in.) |width= |height= |weight=376.4 kg (830 lb) |valvetrain=Pushrod-actuated, two valves per cylinder |supercharger=Single-speed centrifugal type supercharger |turbocharger= |fuelsystem= |fueltype= |oilsystem= |coolingsystem=Air-cooled |power=575 hp (429 kW) at 1,950 rpm |specpower= |specfuelcon= |oilcon= |power/weight= |compression= |reduction_gear=Epicyclic gearing }} See also{{Aircontent|related=
|similar engines=
|lists=
|see also= }} References
1. ^Gunston, p.163 2. ^Connors, p.79 3. ^Smithsonian
External links{{Commons category|Pratt & Whitney R-1860}}{{P&W piston engines}}{{US military piston aeroengines}}{{DEFAULTSORT:Pratt and Whitney R-1860}} 3 : Radial engines|Pratt & Whitney aircraft engines|Aircraft piston engines 1920–1929 |
||||||||||||||
| 随便看 |
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。