Tip jet

[1] Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not requiring the presence of a tail rotor.

[4] If the helicopter's engine fails, the tip jets on the rotor increase the moment of inertia, hence permitting it to store energy, which makes performing a successful autorotation landing somewhat easier.

However, the tip jet also 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.

During the 1900s, Austrian Ludwig Wittgenstein investigated the use of tip jets to drive an aircraft propeller while studying aeronautical engineering at Manchester University, in the United Kingdom.

[12] During the Second World War, German engineer Friedrich von Doblhoff suggested powering a helicopter with ramjets located on the rotor tips.

[19] The second FB-1 was modified to investigate a tip-jet driven rotor coupled with a pair of propellers mounted on stub wings; it was later renamed the Jet Gyrodyne.

[20] Another rotorcraft developed by the firm, the Fairey Ultra-light Helicopter was a compact side-by-side two-seater vehicle that used tip jets powered by a single Turbomeca Palouste turbojet engine.

[21] The type led a contract from the Ministry of Supply for four flight test-capable aircraft; the Ultra-light's capabilities were subsequently demonstrated at numerous military exercises, airshows, and even at sea.

[29] Reportedly, the larger Rotodyne Z design could be developed to accommodate up to 75 passengers and, when equipped with Rolls-Royce Tyne engines, would have a projected cruising speed of 200 knots (370 km/h).

[37] According to author Wayne Mutza, the US Army had found the YHO-1 to be an excellent weapons platform, but were compelled to abandon its interest by political opposition to the procurement of a foreign designed rotorcraft.

As envisioned, the projected Super Djinn would have adopted the newer Turbomeca Palouste IV engine alongside other changes for greater power and endurance than the original production model.

Hot tip jets in this context are a form of simple pressure fed rocket engine as both fuel and oxidizer are being supplied, mixed, and ignited.