Helicopter The Piasecki X-49 is a four-bladed, twin-engined, experimental compound helicopter under development by Piasecki Aircraft. The X-49A is based on .br SUPER FAST Piasecki X 49A Helicopter for US Military - Thanks for the watching video - please subscribe my channel,br 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 .br Helicopter The Piasecki X-49 is a four-bladed, twin-engined, experimental compound helicopter under development by Piasecki Aircraft. The X-49A is based on .