The Lockheed XH-51 (Model 186) was an American single-engine experimental helicopter designed by Lockheed Aircraft, utilizing a rigid rotor and retractable skid landing gear.
The XH-51 was selected as the test vehicle for a joint research program conducted by the United States Army and United States Navy to explore rigid rotor technology.
Variants
XH-51A
four place, three-bladed rotor
XH-51A Compound
modified with a four-bladed rotor and stub wings and an auxiliary 2,900 lbf (12.9 kN) Pratt & Whitney J60-2 engine.
XH-51N
five place, three-bladed rotor for NASA test purposes.
Model 286
Five place civilian or military light helicopter offered for sale, none were sold.