Gas turbine

[Submarine Tom]

Thank you YellowJ and Jimbo, very interesting indeed.

-Tom

[powerabout]

Didnt HeliMusters in OZ have about 30-40 47's 20 years ago?

Re piston to turbine , no contest if its flying, about the only thing a piston can do is have a bit more instant grunt, no turbo lag you could say.
PS I'm a Hughes man myself..how could you ever fly in a chopper with 2 blades! after that I guess its French but I had many fantastic memories in 500's skiing in NZ, stunts that I have not yet seen in a Hollywood movie

[Submarine Tom]

Turbo lag - nothing a good pilot can't compensate for.

[Jimbo1490]

The modern helicopter airframe is the *perfect* match for a gas turbine engine. Light helicopters would never have become so popular as they are today without the gas turbine engine. That being said, it's interesting to see how the definition of 'light' vs 'utility' helicopter morphed over the years because of the turbine engine, and how the model 47 was left obsolete as a result. When the 47 was introduced, it was considered a utility helicopter, with an impressive payload. With the introduction of the 206 in the late 60's, the 47's payload was no longer impressive. Larger engines and rotor blade upgrades helped the 47 keep up somewhat; the 'Big Blade ' conversion 47's even had a greater payload than a 206B. But in the end, the 47 was a 'bare bones' airframe, VERY noisy and without a 'real' cabin. It had the old style dynamic system and an increasingly high-strung piston engine also, both negatives.

That last place the original light versions could still find commercial success was in pilot training and the heavy converted airframes all went to crop dusting. When the R-22 came along, it far cheaper to run so it made MUCH more sense as a trainer, which obviated the need for most of the 47 fleet. Advances in crop dusting airplanes obviated the need for most of the heavy conversions as well.

Bell could've done a turbine version like Soloy did, but then you're still stuck with the old rotor hub and controls. They could have transplanted the Bell 206 controls (like Soloy did) but you still have the old hub. Even replacing the hub, you still have no real cabin, which limits what you can do with the thing. And in the end it would have to compete with the Eurocopter Alouette and Llama, not something Bell would be thrilled about. The world already has all the turbine powered 'bubble' 'copters it needs, so why make more

Jimbo

[powerabout]

Doesnt the 206 also have a wierd engine to rotor clutch whereas the H500 has a sprag like everyone else?

[Jimbo1490]

All the helicopters (I'm aware of) powered by the RR/Allison 250 lack a clutch of any kind, as the engine is a 'free turbine' engine. The Bell 47 had a sprag clutch.

Jimbo

[powerabout]

here's one from way back
Never made it to production

[powerabout]

here's 2 of 4 in one boat
These T55's will go faster in this boat that any chopper ever did!
( ok ones out of view)

May I inform you peers, that the thread opener Daniel Skira decided to quit his membership on this Forum!

Repeated personal attacks by some of our well known drivel and destruction experts, made him decide to leave.

We have lost a well respected NA with a sensible hand for drawing classical beauties.

A man of good temper and a sense for harmony and nice behaviour.

It is a pity that such people are pissed off here by two or three internet rowdies.

Regards
Richard