Turbine Engine Question

FutureLeader

FutureLeader

New Member
To all you pilots out there that fly turbine aircraft (TurboProp or TurboFan), is it possible to engage reverse thrust while the aircraft is in flight? If so, what effect does it have on the aircraft? Also, does reverse thrust really reverse the thrust of the aircraft? Your answers will be appreciated. Thank you.
 
Mate, ill let the experts answer this one, but from my knowledge it will not let your engage reverse thrust untill the wheels are on the ground.

Cheers
 
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is it possible to engage reverse thrust while the aircraft is in flight?

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Some aircrat have 'lockouts', some do not. Like if you pull the reverse levers with the throttle idle in the MD-88, you're going to get reverse thrust. Well, not for long because then you've got controllability problems. But it's recoverable if it's not full reverse.

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If so, what effect does it have on the aircraft?

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Bad stuff!

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Also, does reverse thrust really reverse the thrust of the aircraft?

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Depends on the aircraft. The reversers in the MD-88 just made a bunch of noise, but most of the braking came from the 'clamshells' opening up. The MD-90's worked great, but it didn't have clamshells, but a 'sleeve-type' device.
 
Example of "clamshells"

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Example of "sleeves"

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Cool! Now I can tell the difference b/w an MD-88 and an MD-90.
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737s have the sleeve type (except for the -200s, they have clamshells), and I THINK they have restrictors to keep them from operating in flight. I could be wrong, though. I DO know that Cessnas/Diamonds/Senecas do NOT have reversers, therefore they cannot be reversed in flight......except in windy conditions.
 
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is it possible to engage reverse thrust while the aircraft is in flight? If so, what effect does it have on the aircraft?

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In the King Air, yes you can. I've done it in the sim, although I didn't go to full reverse. The aircraft comes down like a rock.
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In the Saab, it is not possible unless you disengage the "Flight Idle Stop" by pulling a red handle on the center pedestal. Then you can bring the power levers into beta (bad enough for controlability) and then reverse (much worse). In normal operations, there is a mechanical stop that keeps us from going over the "gates" into beta/reverse when certain conditions are met regarding the Weight on Wheels switches.

As for reversing thrust, in a sense yes, it does reverse the thrust. Basically, the propeller pitch goes negative, so the props are now pushing instead of pulling. But the props themselves don't start turning in the opposite direction. It is just due to the blade angle.
 
We were able to use idle reverse thrust on the inboard engines of the DC-8 in flight. These were seldom used but it did come up occasionally since the DC-8 has no speed brakes and is very hard to get down.

When the new big fans with more effective T/Rs were installed we pretty much stopped doing it at all. If they were to be used we had to call the flight attendants and make sure everyone was seated with galleys secure, because anything not anchored was coming forward when those engines went into reverse.

According to a friend at UPS they don't use them either out of consideration for the age of the airplanes and the stress.
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The CRJ700 doesn't allow you to engage them without weight on wheels. They are mechanically and hydraulically locked out.
 
Thanks for all the responses guys, I really appreciate them. Doug, thanks for the pictures, they really helped out. I hope your 757/767 bid goes well
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I am not sure whether this is true, but someone told me the C17 can engage full reverse thrust in flight then drop like a stone at about 30000fpm. That would at least be one concievable use of reverse thrust in flight--to bring the airplane down in a hurry.
 
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"sleeves?" Always thought they were called "diffusers"

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I work for an airline where we call MD-88 rudder load limit devices a "pork chop".
 
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Mmmmmm - pork chops!!!

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Seeing as how you're a beef man too, R2F, I gotta know...

you a sirloin, T-bone, or filet man?

........nice cut of beef sizzling in butter as it's served........

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I am not sure whether this is true, but someone told me the C17 can engage full reverse thrust in flight then drop like a stone at about 30000fpm. That would at least be one concievable use of reverse thrust in flight--to bring the airplane down in a hurry.

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That is true from what I have been told too.
 
30,000FPM? That would require 300kts straight down. (30,000' = 5 nautical miles). Is that possible without thrust from the engines working to move the aircraft forward?
 
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