North American XP-51G
The XP-51G was a development aircraft that combined the light weight airframe developed for the XP-51F with an experimental Rolls Royce RM-14SM engine, capable of producing 2,000hp at 20,000 feet. The new aircraft achieved a top speed of 495 mph, and a climb rate of 5,000 feet per minute, well over 1,000 feet per minute faster than the P-51D. However, the new Rolls Royce engine was too complex and did not always produce its best power. The last production version of the Mustang would be the P-51H, combining the light weight airframe of the XP-51F with a more powerful Merlin.
How to cite this article:
Rickard, J (pending), North American XP-51G, http://www.historyofwar.org/articles/weapons_xp-51G.html