Bergen Research Engineering flying crane


Unsolicited proposal for a flying crane submitted to the Army by the Bergen Research Engineering Corp. of Teterboro, New Jersey. Bergen was a small firm known for transmissions, mechanical drives, and high-temperature/high-pressure valves.

The design consists of three four-blade main rotors powered by gas-turbines; two 5,500hp Pratt & Whitney T34 would have been installed on the outriggers, and a 1,050hp General Electric T58 would have been inside the fuselage. The power transmission system connecting them was designed by Fred L. Parsons and Stan W. Baker, president and vice president respectively of Bergen. It consisted of separate shafts and gears that allow one of the engines to drive all of the rotors during an emergency, but otherwise allowing each engine to drive their own rotors during normal flight. An automatic locking mechanism could be enabled to connect the two outrigged rotors rigidly during engine failure, triggered upon changes in the speed of the drive shafts. Not only did this unique transmission layout eliminate the need for rotor-starting clutches, but Bergen claimed that it would also reduce vibration issues that burdened other existing designs at the time. 

Forward flight speed would be affected by increasing power to the rear rotor and pitching the the aircraft forward. Collective pitch to all three would be increased to maintain altitude. The outrigged rotors counteract torque by rotating in opposite directions, while torque from the rear rotor would be neutralized by the jet exhaust from the outrigged engines. The aerodynamics behind the design were researched by Professor Gordon B. McKay of Columbia University, New York.

The machine would be able to carry various types of load and containers, with tension loads in the outriggers taken by cables attached to the payload. It would have had a maximum gross weight of 80,000 lbs and an empty weight of 44,400 lbs. Flyaway cost was estimated at $900,000 and total operating cost was at over $1,000 based on 30 hours of flight per month. Cost per ton-mile was estimated at $1.20.