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-   -   New "No dead man's curve" two seater (https://www.pprune.org/rotorheads/338625-new-no-dead-mans-curve-two-seater.html)

rotorrookie 10th Aug 2008 14:57

New "No dead man's curve" two seater
 
This is interresting, specialy if it has no dead mans curve

No Gears Just Air©

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Old Skool 10th Aug 2008 15:26

It looks like the whole flight envelope may be the dead mans curve...:hmm:

airborne_artist 10th Aug 2008 15:53

I've only seen tip-jets in a museum, and I feel there must be a good reason. If they were so great they'd be out there now.

Ioan 10th Aug 2008 15:57

Was I the only one to cringe slightly at their choice of music, 'Dangerzone', in a promotional video of a helicopter while the caption 'To develop the safest helicopter ever made' rolled by?! :D

That aside mind, it does look... kinda fun to fly!

Devil 49 12th Aug 2008 08:06

If it's such a good idea, why isn't Sud-Ouest/Aerospatiale/Eurocopter still building them? Perhaps because a 29 gph, 110 knot 2 seater isn't efficient- and probably not much fun either with a high inertia rotor, slow to accelerate and decelerate.

klaus_a_e 12th Aug 2008 08:53

Never fly the A-model of something...
 
Well, just because other companies are not continuing their research on tip-jets doesn’t mean it’s bad. There have been some examples in the history of engineering where old, never well developed systems, got a big revival.
I still don’t understand why there would be no dead man’s curve?! He still needs to autorotate somehow if the engine stops working, right?
Ioan, I found the music pretty funny too, probably they mean this thing is not autorotating at all so thats why there is no dead man’s curve, that’s why the Dangerzone…

Fareastdriver 12th Aug 2008 12:30

The problem with tip jets is noise. The only one with tip jets that I have seen flying was the Fairy Rotadyne and you could hear that miles away. High velocity air coming out of a jet whether burnt internally or supplied externally creates noise as it passes through the low velocity air around it. Years ago airliners had hush kits but these are unwieldy and inefficient especialy on the end of a rotor blade. Turbofans have the high velocity air from the core engine mixed with the air from the fans so the velocity difference is reduced progressively and so is the noise.
On a rotor system in forward flight the vast difference in airspeed between the advancing and retreating blade would create a one-per-rev pulsing effect which would be even more annoying. I do not think a 250 could supply enough air for a low pressure tip jet but if it could there would be some massive plumbing.

Maybe they have found a way around it.

docstone 12th Aug 2008 16:27

We shall see, but clearly they're winning over some folks...

Rotorhub: The Information Hub of the Helicopter Industry

The Board and Executives are hardly tire kickers either.

Ian Corrigible 12th Aug 2008 18:01

Hmm... :suspect:

Reminds me of the 'order' for 200 Groen Bros Hawk 4 autogiros from the Shanghai Energy and Chemical Corporation. Or Hiller's production of 500 FH-1100s p.a. in Zhangjiakou. Or Brantley's production of 300 B-2s p.a. in Qingdao. (Or the various wild & wacky production claims by Kamov, Mil and Kazan over recent years...)

Methinks someone is counting their poultry before it has hatched.

Impressive collection of backers nonetheless.

I/C

500e 12th Aug 2008 21:30

And still no real life picks or video of a finished helio, but a lot of capital raised, is it a good helio or a good story?
Have seen a Djinn fly in my youth, NOISY or what.
A link to one for sale or sold,
eBay.com.my: DJIN HELICOPTER 1956 RARE FIRST JET POWERED SO.1221 (item 330253284120 end time Jul 26, 2008 08:49:11 MYT)

Paul Cantrell 15th Aug 2008 03:14

I thought another problem with tip jet helicopters, besides the noise, is that the centrifugal force at the blade tip tended to work the hot metal parts of the jet...


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