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Why did the half-plane, half-helicopter not work?

bbc.co.uk

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Re: Why did the half-plane, half-helicopter not work?

#11

Post by TheOtherHobbes »

detaro wrote: post #4

What's the state of the art in active anti-noise technology for helicopters? I've read about that kind of thing a few times, but don't know what actual numbers are.

It would be hard to anti-noise the Rotodyne because it literally had small jet engines on the end of each rotor - which was why it so incredibly loud in VTOL.

I can't find actual noise figures for it, but I suspect it wasn't all the much louder than some modern jet liners. But jet liners land at out-of-city airports, and the whole point of the Rotodyne was that it could land in the middle of a city - and you're not going to get certification for that for a plane that can be heard miles away.

I'd guess it was unbearably noisy inside the cabin too.

Here's a sales video, with vintage cheesy music and equally vintage British accents:

https://www.youtube.com/watch?v=u4Z1UnRZDyo

Re: Why did the half-plane, half-helicopter not work?

#12

Post by curtis »

Another tip jet helicopter was the Sud-Ouest Djinn [1] from the 1950s. This design was somewhat successful, with 178 units being built. Unlike other tip jet designs, the Djinn used a fixed gas turbine to drive an air-compressor, and the blades were simply powered by compressed-air tip jets. Since tip jet driven rotors don't generate a lot of torque, the Djinn didn't have a tail rotor.

[1] https://en.wikipedia.org/wiki/Sud-Ouest_Djinn

Re: Why did the half-plane, half-helicopter not work?

#13

Post by melling »

johnjackamend wrote: post #7
Melkman wrote: post #2

Hmm, I'd say that V22 Osprey does work. It's still a compromise and a full heli or full plane is better suited for most tasks but a hybrid does have its use.

Eh. The total cost of its program ($35.6 billion) almost came to exactly $1 billion per death incurred by accidents during its testing from 1991-2000(36 fatalities). All that money and life spent on a somewhat functional newly minted freedom boner.

Is $35 billion a lot of money? We did get a step forward in engineering. The lessons learned advanced our knowledge forever. The money spent in actual wars for little things like air conditioning, for example, cost more:

http://www.npr.org/2011/06/25/137414737/among-the-costs-of-w...

Re: Why did the half-plane, half-helicopter not work?

#14

Post by michaelbuddy »

georgemcbay wrote: post #10
Melkman wrote: post #2

Hmm, I'd say that V22 Osprey does work. It's still a compromise and a full heli or full plane is better suited for most tasks but a hybrid does have its use.

That was my first thought as well (off the title alone), and I'm somewhat surprised the article didn't mention the Osprey at least in passing. I mean, you can certainly argue that the program was not worth the cost in money or lives lost (as is already being done in this subthread), but ultimately the thing works -- as someone who lives in San Diego, I see them flying overhead multiple times per week.

I was watching a documentary years ago (vhs tape) that talked about how there were problems with the Osprey. The lingering question I had was whether it was a problem of that design or the concept. https://en.wikipedia.org/wiki/Accidents_and_incidents_involv...

Re: Why did the half-plane, half-helicopter not work?

#15

Post by sandworm101 »

Too big and too complex. Just like the Osprey.

But Canadair has it all figured out. The CL-84 was a tilt-rotor, tilt-wing aircraft that was landing troops on US carriers 40 years ahead of the Osprey. It probably had 1/100th the part count.

https://en.wikipedia.org/wiki/Canadair_CL-84

Re: Why did the half-plane, half-helicopter not work?

#16

Post by WalterBright »

Helicopters are expensive - high fuel consumption, high maintenance. They're also inherently much less safe than an airplane. A helicopter is inherently unstable (it wants to crash, whereas an airplane wants to fly), and losing a rotor blade means everyone dies (hence the high maintenance costs).

Re: Why did the half-plane, half-helicopter not work?

#17

Post by kevin_thibedeau »

Melkman wrote: post #2

Hmm, I'd say that V22 Osprey does work. It's still a compromise and a full heli or full plane is better suited for most tasks but a hybrid does have its use.

Although not meant for passenger service, the AH-65 [1] would likely have been a successful hybrid had the stopgap Cobra not been such a resounding success.

[1] https://en.wikipedia.org/wiki/Lockheed_AH-56_Cheyenne

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