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Turbine Question


deanathpc

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O.K. watching some videos today and have a question. may not pertain to helicopters one bit but here goes nonetheless...

 

You see in movies etc. about how jet fighter planes can have a flame out with one of their engines or both based on flying through another jet's wash....

 

My question is can this happen to a Helicopter? Still a turbine engine.... Still can fly in a jet wash of some other aircraft be it a jet, helo, etc etc etc....

 

Anyone experienced this while flying? How do you correct for it? I can understand if you are in a bird with two engines but if it's only one and you have this happen to you I would think an autorotation is in quick order or is there time to restart the engine?

 

Just a passing thought... Things that make you go.. hmmmmmmmm :)

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I believe if you were to fly through the "jet wash" of an airplane, in a helicopter, you would flip over, due to wake turbulance. :o As for "flame out", the Jet Ranger I flew had an engine re-ignighter, so it seems to be possible. :huh:

But don't quote me on that, I only have ten hours in turbines. :(

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I think that jet wash or wake turbulence would cause control problems (i.e. loss of control) long before an engine flame out. However, I know that flying in snow or heavy rain can be an issue. The Jet Ranger, equipped with particle separator has to have the reverse flow fairings installed prior to flying in falling snow due to flame out possibilities. Also, the Koala has a requirement to place the IGN (ignition) switch to CONT (continuous) if adverse weather conditions are expected during flight, with possible risk of engine flame out.....heavy rain, snow?..not sure as Agusta does not define what weather conditions it is referring to. We would just turn it to CONT whenever flying in decent rain or snow.

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I would think that the "Top Gun" style flame out that could occur in a fixed wing turbine airplane would be due to the turbulent airflow going into the engine inlet, disrupting the smooth continuous flow of air through the engine....think Turbofan....its a straight tube from front to back that depends on a smooth continuous airflow THROUGH the engine....Helicopter engines dont function in the same manner....In the EC-120 and OH-58 I fly, there is not a straight through flow of air in either engine....the EC-120 air intake is on the starboard side and gets it air through the side of the engine through the particle separator. Just my $.02

 

 

Ryan

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Well I don't have a whole lot of turbine time in Helicopters, but the issue with turbines in general is the disruption of airflow into the compressor section causing a compressor stall. It could happen in a helicopter I would imagine, but it would be more likely from something like the Air Bleed Control Valve being stuck closed. In the Heli I primarily fly there is a particle separator in front of the compressor inlet therefore the air has to pass through it and be straightened out before entering the turbine. Yes, the Jetranger and others have a re-light in the case of falling snow or rain and snow baffles for when there is the possibility of snow entering the turbine.

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Video of the certification tests for a jet engine, including hail, icing and water ingestion tests:

 

 

short video of a water ingestion test on a Rolls Royce aircraft engine:

 

a little bit of rain isn't going to hurt one of these things...

Edited by lelebebbel
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Video of the certification tests for a jet engine, including hail, icing and water ingestion tests:

 

 

short video of a water ingestion test on a Rolls Royce aircraft engine:

 

a little bit of rain isn't going to hurt one of these things...

These are TurboFan Engines.. Not QUITE the same thing. I worked on F-14's in the Navy back in 97-98-99. I know real well what you are talking about with a flame out in these style engines... a turbo fan engine like in these vid,s get 70-80% of their thrust from the large Fan and bypass air.. Not the same in a fighter Jet.. they are turbo Jet engines. Multiple compressor stages and turbine stages, and all resultant heat and ingnition results in their high thrust,, But if interupted even briefly, They are out. They rely on the smooth flow into over and throughout the entire process.

 

Helicopter turbines do not, at least in most cases, get a direct injection of air like an f-14 or f-18 intake. They have either screens, particle sep's etc to get through first... Moisture can get in, But is usually already so thinned out it wouldnt matter much.. But I'm sure they have those reg's spoken about in prevous post like leaving the ignitor on in bad weather, for a reason.. They would know best, Or just being safe!

 

joe

Edited by Jsta22
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Gomer wow I haven't seen you in some time.. :) No it wasn't really a movie but turbines still have me a little confused. Just happened to be thinking about this one day and thought I'd post the question...

 

Thanks to everyone who has answered though!!!! But if everyone notices there is some speculation here and different opinions. How would one find this out for sure? I could imagine control issues would kick in first and foremost..... Is the exhaust of a turbine helo enough to cause issues also?

 

Basically I was watching a video where they were doing some formation flying. And knowing that jets have to be offset when flying due to flame outs etc. I was wondering if Helos had the same problem... that's all....

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In a former life I spent a lot of time flying in helicopter formations, some of them rather large. Often we flew in very tight formations, within a rotor disk of the other ship. I've never heard of an engine failure due to this. Failure from projectiles hitting them, yes, but not from rotor wash. The engines are designed to have the airflow be convoluted, not straight, and they can handle a lot of moisture and other contaminants through particle separators and other devices.

 

The short answer is 'no'.

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30 years ago in Oz, a TV B206 was flying around a new power station getting footage.

The pilot flew through the exhaust plume to get a dramatic vertical shot down the chimneys, and the engine stopped. One quick auto and he was on the ground, remembering that an air-breathing engine needs FRESH air.

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Is it n enough thrust to cause control problems in a helo? No...

 

 

Most of the expelling gases, or thrust energy in a helo's turbine is absorbed by it spinning the drive turbine, which in turn spins the rotors. So in short, most of its energy is used to turn the rotors, so not much left for any Real amount of thrust to cause too much of a control problem..

Edited by Jsta22
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Now add another chamber behind that Driven turbine shaft and inject fuel there?? Thats a different story, Now you have a direct thrust Jet engine, or afterburner. Nice cool looking flames will shoot out the back too! resulting in added thrust that just might be enough to cause control probs.

Josepp

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