The Piasecki X-49 doesn’t look like any other aircraft you’ve seen before. The twin engine beast is based on a Sikorsky YSH-60F Seahawk but has a few extra features like lift wings and an overblown box fan on the back end. The result is an unprecedented extraction aircraft.
According to ArmedForcesUpdate:
The Piasecki X-49 is a four-bladed, twin-engined, experimental compound helicopter under development by Piasecki Aircraft. The X-49A is based on the airframe of a Sikorsky YSH-60F Seahawk, but utilizes Piasecki’s proprietary vectored thrust ducted propeller (VTDP) design and includes the addition of lifting wings. The concept of the experimental program is to apply the VTDP technology to a production military helicopter to determine any benefit gained through increases in performance or useful load.