Years ago, I viewed a documentary on experimental helicopters and saw a craft that caught my attention. The craft was a hybrid of 4 mini-jets (two on each side), stubby wings, rotors with a boxcar-like appearance. Not sure if it was made by Bell or Sikorsky and it was an experimental "proof of concept". Meant to be a "taxi" shuttling passengers on short suburban/urban routes or to nearby cities. Anyone know the name of this vehicle?