Fixed Wing

southkogs

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Y'know ... it's funny in an ironic way: You would have to drug me to get me into a parachute or hang glider. But in a light airplane or sail plane, I'll do nearly anything without question.
 

achris

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Technically Helicopters don't fly, they just beat the air into submission or so I was told by a Marine aviation mechanic.

Err, yeah, they fly, and they can 'stall' too....

Let the fun begin. :D
 

southkogs

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... and they can 'stall' too .... Let the fun begin. :D
I was talking with one of the instructors up at Ft. Campbell about the CH47 Chinook (we were in the SIM), and there is an account of a crew pulling a Chinook through a complete barrel roll. I can't recall the conditions that caused it, but a stall was involved and the pilot opted, as his best chance, to go for the complete push over.

Neither the Army or Boeing can account for how that bird made it through the roll!
 

achris

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I was talking with one of the instructors up at Ft. Campbell about the CH47 Chinook (we were in the SIM), and there is an account of a crew pulling a Chinook through a complete barrel roll. I can't recall the conditions that caused it, but a stall was involved and the pilot opted, as his best chance, to go for the complete push over.

Neither the Army or Boeing can account for how that bird made it through the roll!

Are you talking roll or loop? I have actually seen video of a chopper doing a loop... Hard to watch once, you have to watch it twice (or three or four times :D)

I know most people think a stall is when the aircraft slows too much to generate lift on the wing, hence 'falls out of the sky', and argue that as a chopper can hover, it can't stall. But as a choppers' wings are the rotors (hence the reference 'rotary-wing'), yes, they do stall... With exactly the same result!

Chris.......
 

southkogs

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Are you talking roll or loop? I have actually seen video of a chopper doing a loop ...

Nope: I know a couple of whirlys that have consistently performed loops (Apache is one, and I think the Lynx has done 'em). This was a CH47 Chinook and as I best understand it: he got pushed (rolled) during a climb, and as the helicopter stalled out (roll was obviously very steep) the pilot felt his best chance of recovery was to go all the way over and use the airspeed generated in the fall. As a result the 47 rolled completely during an altitude change ... effectively a barrel roll.

If a helicopter couldn't stall then auto-rotation would work ... but not too many folks like to test that out.
 

achris

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Nope: I know a couple of whirlys that have consistently performed loops (Apache is one, and I think the Lynx has done 'em). This was a CH47 Chinook and as I best understand it: he got pushed (rolled) during a climb, and as the helicopter stalled out (roll was obviously very steep) the pilot felt his best chance of recovery was to go all the way over and use the airspeed generated in the fall. As a result the 47 rolled completely during an altitude change ... effectively a barrel roll.

If a helicopter couldn't stall then auto-rotation would work ... but not too many folks like to test that out.

Impressive....
 

Gyrene

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Well, there were autogyros, that had a rotor in place of a wing.....

C4-4.jpg


But they are largely gone.
 

Water logged

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I guess I've never heard a helicopter called a rotary winged aircraft.
I've always heard them called helicopters, or choppers, or helos.
I've never heard the rotors called wings either.

So now I have learned something.

I wonder if the "journalists" that use the term, know what it means.

Lately it's rare for a journalist to understand the meaning of what they are saying.

Glenn
 

achris

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I guess they fit the definition of STOL... :D
 

Fleetwin

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Airplanes (fixed wing) fly. Helicopters (rotary wing) beat the air into submission. ;)
 

DaNinja

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A stall in a rotary-wing aircraft is usually from the retreating blade. The blade that is going the opposite direction of flight is not gaining any forward wind to support the lift equation. Velocity squared is a big part of a lift equation and when one side of the disc is very positive and the other side is very negative, bad things happen.

At high speeds the retreating blade is prone to stall and the resulting dynamics of the rotor system could result in the mast or blades leaving the aircraft.
If the pilot recognizes it early enough, you can correct the condition. At a certain point it is beyond recovery.

I accidentally put a Cobra past 195 knots once in a dive and was able to recover it as it started to shudder and roll. It scared the bat snot out of me.

http://www.copters.com/aero/retreating.html

Let me dust off my Commercial Instrument Rotary-wing to see if that explanation would pass a check ride oral exam. lol
 

southkogs

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Sorry guys: going slightly off topic for a moment -

Hey DaNinga: as a "dude in the know" how often do you actually utilize those more high performance maneuvers in an Apache? For a helicopter that thing has a pretty slick flight envelope, but it's primary roll has typically been anti-tank ... even over ground support, right? You don't really do much ACM in that, do you?

I've always heard that the Cobra will try to kill the pilot who flies it, but it's still a cool lookin' helicopter to see flying. I got to marshall a couple of Marine birds out a few years back. It was fun working right up on 'em.
 

DaNinja

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Sorry guys: going slightly off topic for a moment -

Hey DaNinga: as a "dude in the know" how often do you actually utilize those more high performance maneuvers in an Apache? For a helicopter that thing has a pretty slick flight envelope, but it's primary roll has typically been anti-tank ... even over ground support, right? You don't really do much ACM in that, do you?

I've always heard that the Cobra will try to kill the pilot who flies it, but it's still a cool lookin' helicopter to see flying. I got to marshall a couple of Marine birds out a few years back. It was fun working right up on 'em.

It really depends on the threat and the environment as to how you use the machines you have. A Cobra was built off a Huey frame during Vietnam. Low intensity, jungle warfare where high energy tactics were the norm. It was later modified in the cold war as a tank killer to deliver TOW missiles on enemy tanks..

The Apache was purpose built as a tank killer. It was designed to stand off from a distance and lob Hellfires at Russian tank columns in the Fulda Gap. Sometimes you need to adapt to your threat though. Desert Storm the Apache was key at destroying armor and ADA sites from a standoff range. Iraqi Freedom called for a return to some high-energy tactics since you really do not want to make a habit of hovering over Sadr City.

BTW: This is what high energy tactics look like when they go wrong.
https://www.youtube.com/watch?v=BcTDwJcO_os

Funny about ACM.. I just pulled an old manual off my shelf. FM 1-17 Air-to-Air Combat, 1984. I retired four years ago, but dogfights with helicopters was not what the weapon systems were designed for.

In an attempt to return to the fixed/rotary discussion.. An airplane's wings are fixed/stationary and require a propeller or jet propulsion to get airflow over the wings. At a certain speed the wing produces lift. Below that speed the wing no longer produces lift.

A helicopter uses an engine (gas or turbine) to spin its wings until they are at a speed that will produce lift. When the engine(s) no longer spins the rotating wings, the pilot has no choice but to auto-rotate to the ground. For those concerned about engine failures in a rotary-wing aircraft, a small fixed-wing aircraft needs about a football field to put the aircraft down. A decent helicopter pilot would put the aircraft in the end zone after an engine failure.
 
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