Design and Development
The Hiller HJ-1 Hornet was an early attempt to build a jet-powered helicopter using ramjets. Before that there had been experiments with the XH-26 Jet Jeep tip rotor pulse jets. The HJ-1 ramjet tipped rotor propels the rotor and the aircraft. Unlike a conventional helicopter, this mechanically simple design avoids the need for a tail rotor.
Unfortunately, the tip speeds on helicopter rotor blades are subsonic, and ramjets are inefficient at subsonic speeds due to low compression ratio of the inlets. Therefore, the Hornet suffered from high fuel consumption and poor range. Also, the vehicle suffered from low translational speeds and the ramjet tips were extremely noisy. In the event of power loss, autorotation was found to be difficult due to the drag from the ramjet nacelles.
The vehicle exhibited powerful lifting capacity, and there was some hope for military uses, but the high noise, poor range, and high night-time visibility of the ramjet flames failed to attract sales.
Read more about this topic: Hiller YH-32 Hornet
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