Editing Hyper engine (section)

{{Short description|Hypothetical aircraft engine design}}
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[[File:Liberty L-12-1.jpg|thumb|Liberty L-12 engine, from which Hyper Engine No. 1 was derived]]

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&nbsp;hp/in<sup>3</sup> (46&nbsp;kW/L) of engine displacement for a weight of less than 1&nbsp;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 specially 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&nbsp;hp (895&nbsp;kW) from 1,830&nbsp;in<sup>3</sup> (30&nbsp;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 also increase the weight, and thus not have any significant effect on the power-to-weight ratio. To meet the goals, more radical changes were needed.<ref name="White211">White p&nbsp;211</ref>

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.