Hyper engine
| Liberty L-12 engine | |
|---|---|
 |
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| Liberty L-12 engine, from which Hyper Engine No.1 was derived | |
| Type | One cylinder converted into "Hyper Engine No. 1" |
| National origin | United States |
| Manufacturer | Continental Motors |
| Designed by | Sam Heron |
| First run | 1932 |
| Major applications | Experimental Engine |
| Number built | 1 |
The hyper engine was a 1930s study project by the United States Army Air Corps (USAAC) to develop a high-performance aircraft engine that would be equal to or better than the aircraft and engines then under development in Europe. The project goal was to produce an engine that was capable of delivering 1 hp/in3 (46 kW/L) of engine displacement for a weight of less than 1 lb/hp delivered. The ultimate design goal was an increased power-to-weight ratio suitable for long-range airliners and bombers.
At the time, no production engine could come close to the requirements, although this milestone had been met by special modified or purpose-built racing engines such as the Napier Lion and Rolls-Royce R. A typical large engine of the era, the Pratt & Whitney R-1830 Twin Wasp radial, developed about 1,200 hp (895 kW) from 1,830 in3 (30 L) so an advance of at least 50% would be needed. Simply scaling up an existing design would not solve the problem. While it would have increased the total available power, it would not have any significant effect on the power-to-weight ratio; for that, more radical changes were needed.
Several engines were built as part of the hyper program, but for a variety of reasons none of these saw production use. Air-cooled engines from a variety of US companies were delivering similar power ratings by the early 1940s, and the licensed production of the Rolls-Royce Merlin as the Packard V-1650 provided hyper-like performance from an inline while the Allison V-1710 did the same from a US design, one produced as a private effort outside the hyper program.
Improvements in construction and lighter materials had already delivered some benefits on the way to higher power-to-weight ratios. Aluminum was being introduced in place of steel as the quality and strength of aluminum alloys improved during the 1930s; this lowered engine weight noticeably, but not enough to achieve a 50% overall improvement. To reach that goal, the power of the engine would also need to be increased. Power is a combination of energy and the rate it is delivered, so to improve the power-to-weight ratio, one would need to increase the operating pressures of the engine, the operating speed, or a combination of both. Further gains could be made by eliminating losses like friction, combustion inefficiencies and scavenging losses, delivering more of the theoretical power to the propeller.
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Wikipedia