Whether you call it meddling or injecting creativity into a hidebound bureaucracy, Congressional earmarks can have some interesting results. Witness the Piasecki-Sikorsky X-49A compound helicopter, now complete and being prepared for flight tests.
A compound helicopter is simply a helicopter with added wings and a forward propulsion system. They enjoyed a brief popularity in the 1960s, and one of the leading companies in the field was Piasecki, founded by Frank Piasecki, rotorcraft pioneer and father of the CH-47. The Piasecki company has revived its 1960s approach, which uses a single ducted propulsor to provide anti-torque control in the hover and forward thrust.
The idea behind a compound helicopter is that wings and propellers provide lift and thrust more efficiently than a rotor, so a compound helicopter can be more efficient at speed. The approach is mechanically less scary than a tilt-rotor, too. Critics suggest that the advantages are offset by weight and the downwash of the wing in the hover; read what veteran Sikorsky test pilot Nick Lappos has to say at Pprune.
Either way, the Pentagon has shown an overwhelming lack of enthusiasm for compounds in general and Piasecki's work in particular. However, Congressman Joe Sestak has other ideas and has been able to keep the project funded, adding $9.5 million this year.