Curtiss P-5 Superhawk

The Curtiss P-5 Superhawk was a high-altitude version of the P-1 Hawk fighter, developed for the U.S. Army Air Corps to test turbo-supercharging. Under a May 1927 contract, five aircraft similar to the P-1A were built with turbo-supercharged Curtiss V-1150-4 (D-12F) engines of about 435 horsepower, the first delivered in January 1928 as the XP-5 for trials and the remainder by that June. The side-mounted turbo-supercharger added nearly 500 pounds to the airframe but dramatically improved high-altitude performance: top speed rose to around 173 mph at 25,000 feet, and the service ceiling climbed to roughly 31,000 feet, nearly 10,000 feet higher than the standard P-1.

The trade-off was sluggish low-altitude performance and added complexity. Only the five examples were built, but the P-5 provided valuable early data on turbocharging that informed later high-altitude fighter and bomber development.