On Fri, 02 Jan 2004 05:28:01 GMT, Charles Gray wrote:

When was the earliest turbine powered helicopter? I khnow that the
turbine is far more effective than an IC engine.
Also, what was the delay? Was it just a matter of nobody really got
around to it, or were there power/reliability issues with the
turbines?

The initial concepts of turbine-powered helicopters were for the
engines (basically compressors) to feed a fuel/air mix to the rotor
blade tips. i.e. ramjets. Part of this research was done in WWII
Austria by Friedrich von Doblhoff, who went on to McDonnell post-war.
Late in the war several test articles were designed, built, and
somewhat "flown", normally to immediate destruction.

The concept survived into the '50s, when the French SNCASO Ariel III
test aircraft first flew on April 18th, 1951. The last Ariel used a
Turbomeca Artouste I turbine engine. The Djinn model (first flight
January 2nd, 1953) was partially derived from the Ariels and was
produced into the '60s. It used a Palouste gas generator to send gas
to the blade tips.

All of the tip-driven helicopters had a common problem - they were
very noisy and used huge quantities of fuel. Compressed air and fuel
fed to the blade tips proved to be a technological dead end and the
industry eventually went to the turbine driving the rotor blades via
shafts/belts and transmissions. The manufacture of small but powerful
turbine engines light enough to be used in helicopters all but killed
the ramjet idea.

In December 1951 a Boeing 502 turbine engine powered a Kaman K-225.
On July 24th, 1953 Sikorsky flew the turbine-powered S-52 using a
Turbomeca Artouste I. On March 12th, 1955 the Sud-Est SE 3130
Alouette II became the first turbine-powered helicopter to go into
series production.

John Hairell )