This week in 1952
A chilly maiden flight for the first turbo-rotor helicopter
One can only hope that the pilot in this picture was wrapped up well, given that the flight was taking place during winter in Connecticut. Reported by The Engineer in February 1952, the pilot is in charge of the world’s first turbo-rotor flight. News of the flight was given by the US Navy’s Bureau of Aeronautics, which said the initial flight took place on 10 December 1951.
Sixty years ago, The Engineer had a US correspondent who reported that the Kaman Aircraft Corporation had installed a 175hp Boeing XT-50 gas turbine in a US Navy K-225 helicopter to conduct flight tests of the gas turbine.
The unnamed journalist wrote: ’The turbine installation in the helicopter is similar to a turbo-prop installation in a conventional aircraft. The gas turbine was made by Boeing and has been undergoing tests in land and water vehicles.’
“A great saving in weight has been made by using a gas turbine”
This marked the first application of the turbine in a helicopter and engineers were understood to have expected an improved performance compared to helicopters powered by piston engine.
’Most of the increased performance can be attributed to the great saving in weight which is brought about by the use of a gas turbine,’ wrote our US reporter. ’Whereas the normal piston engine installation of the K-225 weighs in excess of 500 pounds, the turbine installation totals less than half that weight.’
The current issue of The Engineer reports Eurocopter’s X3 reaching a true airspeed of 232 knots (267mph; 430km/h) at only 70 per cent power during test flights in May 2011.
Details of the K-225’s flight envelope were in short supply but we do know that in 1951 engineers were beginning to realise that mechanical simplification was another advantage of the gas-turbine power plant.
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20 Feb 2012 | Updated: 20 Feb 2012 9:47 am
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Readers' comments (3)
There is a legend that on the first flight the pilot radio'd frantically "I'm at 10,000 feet, the throttle is completely shut and I'm still climbing!" as the efficiency of the shaft turbine increased with lower air-pressure and -temperature as the altitude increased. The plot was saved from disaster by being told that there was a fuel-cock just within reach behind his seat.
I recall in the 1930s seeing the precursor of today's helicopters, an autogyro, where the rotor was made to rotate by movement of the aircraft with its normal forwards pulling propeller. With stub wings, too. They must have needed a very long runway to get the rotor turning at a speed which would provide useful lift.
Mike,
autogyros actually don't need a lot of runway to take off, typically less than a normal aircraft. Today autogyro's feature a power takeoff that allows the rotors to be bought up to speed in the feathered position, then change the pitch and perform a jump takeoff. See http://www.youtube.com/watch?v=3RPYWmdv174 for a video.