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Aviation History
1921
1921 - 0308.PDF
which the motors Mi, M2 and M3 are built. The motors(Le Rhone motors, 3I1. producing 120 h.p. reconstructed for the tests) drive two propeller-shafts, revolving in oppositedirections, by means of the transmission gear, and these propeller-shafts in turn drive two wooden propellers, each6 m. in diameter, at about 600 r.p.m. Three petrol tanks are installed near the motors. The entire system, is supported by a large pneumatic buffer,which is kept tightly filled with air through an air-pump driven by the motor ; under the end of each arm three small buffersare similarly disposed. The actual object of these buffers is to reduce the shock in abrupt landings. The observer'sseat, made of three-ply wood, is situated over the propeller and strongly secured to the stationary gear-case by theconcave interior prctpeller-shaft. A machine-gun turret is located on the upper rim of the observer's seat. A parachute is also located beside the observer. It hasa capacity of 250 sq. m., and is so designed that in case of sudden stoppage of the motor it can bear the weight of theentire installation, including the observer. The parachute may be worked in the two follov^ing ways :— 1. Automatically,, in such wise that when a regulator,adjusted for the purpose, falls below a certain number of revolutions of the propeller, it releases a mechanism whichejects the parachute. This ejection from the centre causes the parachute to epen instantly, and tests have proved thatit begins to work after a drop of about 25 m. This device thus insures the captive helicopter against damage., in case MAY 5, 1921 fuel for one hour, but not including the observer and the machine-gun, is about 1,300 kg. It is strongly constructed, and some slight lessening of weight may yet be attained. At starting, about 1,800 kg. were measured, that is,, about .5 kg. per h.p. This figure can be considerably augmented by enlarging the propellers. The original type of captive helicopter with petrol motor power was manufactured by the firm of Dr. Liptak, Ltd., Budapest-Szentlorincz, under the special supervision of my collaborator, Lieut. Eng. W. Zurovec, and the above-named firm owns our patent. It may here be mentioned that 1st Lieut, von Petroczy was most energetic in promoting the work above described. ' 4. Test Flights with Petrol Machine. -The reports of the test-flights undertaken may be summed up as follows :— From April 3 to 5, lift and stability tests at low heights, duration tests up to 60 minutes. From May 17 to June 10, climbing to 10 m.-50 m. al.itude. Results : Lift excess on the ground to a load of 4 men. Perfectly tranquil soaring at an altitude of 50 m. Wind velocity during tests up to 8 m.p.sec. After about 15 successful flight tests, the machine had a breakdown when landing on June 10. The power of the enemy motors, which had been recently repaired, diminished so considerably that there was an insufficient excess of throst, and the machine therefore oscillated violently, especially while being brought down. The crew abandoned it. and the machine turned over on the ground, the propeller-blades THE PETROCZY-KARMAN HELICOPTER Side elevation and perspective view of the machine as it appears from below. the motor should stop at low altitudes. The same mechanismbrings the motor to a standstill at the time of ejecting the parachute. 2. The parachute may be worked by hand, by the observer,who is also provided with a bag parachute for personal safety. We may here observe that there is need for the use of theparachute only when at least two moters have stopped, two motors being capable of maintaining the propellers ata sufficiently high rate of revolution. The climb takes place as follows : When the observer hastaken up his position, the motors are started, and this creates no difficulty by reason of the fact that one motor at workcauses the others to revolve. -The functioning of the motors can be controlled by the observer, and future types of thecaptive helicopter will have the necessary instruments located within reach of the observer. As soon" as the motorshave attained the full number of revolutions, a signal will be given for the loosening of the winch, and the machine willthen, according to present experience, climb at a speed of about 1.2 m. per sec. This climbing speed mainly dependsupon the pitch of the propeller and the direction of the wind, and it can therefore be considerably increased. The captivehelicopter is brought down by reversing the winch. Up to date, the motors have always been run at full power,in which case the excess of lift must be compensated. In future, the motors will be throttled in order to diminish thework of the winch. The total weight of the captive helicopter, with engine and sticking into the earth. Considering the state of the motors, my collaborator, Lieut. Zurovec and I wished to omit the tests (there being a wind velocity of 8 m.p.sec..), but were urged to carry them on by the Commission surveying the tests. The results fully confirmed those already arrived at with model tests, so far as stability is concerned. Observations made in the wind proved that, in addition to the fundamental demand for ample excess of thrust, the position of the centre of gravity of the machine in its relation to the plane of rotation of the propeller is of great importance. The results obtained in that respect, both in theory and by means of practical tests, should be of the utmost value as applied to the construction of a second type- Application of the Captive Helicopter (a) Captive Helicopter with Crew, for Observation Purposes During War on Land.—The advantages of the captive heli- copter as compared to captive balloons are as follows :— They are but slightly visible, and therefore provide limited target area for artillery ; they are mounted with guns and axe specially adapted for shooting upward during attacks by aeroplanes ; they are non-inflammable, they can be started without any loss of time and can be rapidly transferred from one place to another. The comparison may be con- tinued by stating that:—A balloon-section on the south-west front, with one balloon, requires :—1 automobile winch-wagon, 2 automobile gas-wagons, 3 freight wagons, 6 officers and 137 men, whereas a captive helicopter requires :—1 auto- 308
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