Simplify the following text for a Grade 10 native English-speaking person.
Original: The hyper engine was a 1930s study project of the United States Army Air Corps , an effort to develop an aircraft engine capable of delivering 1 horsepower per cubic inch ( 46 kW\/L ) of engine displacement .
Simplified: The hyper engine was a possible aircraft engine model that could produce 1 horsepower per cubic inch of engine displacement .