Helicopters are designed so that if they sustain a loss of engine power, their main rotor will continue to rotate, allowing the pilot to ‘autogyro’ safely to earth.
Ignoring the brochure-speak, there are numerous reasons why a rotary wing aircraft might find itself needing to make a controlled, unpowered touchdown (without the vertebrae-fusing impact). Some light aircarft carry parachutes which support the entire fuselage in such an emergency descent. Try launching a chute above a spinning rotor, though, and the result is obvious.
Today’s invention consists of a number of airbags slung in a pod beneath a helicopter. On sensing a catastrophic loss of engine power, these would be deployed in quick sequence, forming an inflated aerofoil shape (unlike automotive bags, they would be unperforated and remain inflated for several minutes).
This improvised wing would enable a pilot to enter a controlled glide and also cushion the inevitable return to terra-all-too-firma.