- Tip jet
Tip jet refers to the jet
nozzle s located at the tip of somehelicopter rotor blades. The objective is to spin the rotor, much like a Catherine wheel firework.Some Tipjets rely solely on compressed air, provided by a separate
engine , to create jetthrust . Others use anafterburner type system to burn fuel in the compressed air, to enhance the thrust; and some areramjet s or even a complete turbojet engine. Some are rocket tip jets that run off stored propellant such as hydrogen peroxide.Tipjets replace the normal shaft drive and have the advantage of placing no
torque on the airframe, so no tail rotor is required.During the
Second World War a German,Friedrich von Doblhoff , suggested powering a helicopter with ram jets and the first jettip powered helicopter was the WNF 342 V1 in 1943. After the war two WNF 342 prototypes ended up with the Americans and Doblhoff joinedMcDonnell Douglas who subsequently produced theMcDonnell XV-1 . The engineer, August Stephan, who had actually produced the jet tip engines joined Fairey Aviation company of theUnited Kingdom which used them in theirFairey Gyrodyne andFairey Rotodyne aircraft first flying in 1954 and 1957 respectively.Eugene Michael Gluhareff was an early pioneer of tipjets.In engine-out scenarios the presence of tipjets on the rotor increases the moment of inertia, hence permitting it to store energy, which makes doing a successful autorotation landing somewhat easier, however the tipjet also very typically generates significant extra air drag, which demands a higher sink rate and means that a very sudden transition to the landing flare must occur for survival, with little room for error.
Rotorcraft using tip jets
*
Percival P.74 (unable to leave the ground)
*Hiller YH-32 Hornet had good lifting capability but was otherwise poor
*Fairey Jet Gyrodyne
*Fairey Rotodyne
*Fiat 7002
*McDonnell XV-1
*Hughes XH-17 (largest rotor of any type on a helicopter)
* Nederlandse Helikopter Industrie NHI H-3 "Kolibrie" (ca 11 built)
*Rotary Rocket Roton ATV
*Sud-Ouest Djinn None have made it into production apart from the Sud-Ouest Djinn.
ee also
*
aeolipile
*rocket engine
*jet engine References
*http://www.gyropilot.co.uk/downloads/Rotodyne%202%20RTF%20Mod.pdf Accessed
1 February 2007
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