Screens On Jet Intakes?

Tue Jun 06, 2000 12:52 pm

With the constant hazard of FOD and bird-strikes etc. why don't engine mfr's put screens or something over the intakes of jet engines? Is there some technical problem which would preclude this? or is it just the engine mfr's saving $$?
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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 1:04 pm

$$ has nothing to do with it. Such a screen would interfere/reduce the airflow into the engine, causing more problems then benefits.
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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 1:04 pm

The Intakes are made as small as possible to reduce the drag, a screen would increase the drag & restrict airflow. Additionally an aero engine spends 99% of its time out of the flight regime where there is a high risk of damage so the cost's of such a thing if it were possible would not justfy it.
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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 1:05 pm

It won't work for the jet engine!! Try test yourself what is the between difference open your window with screen and without screen. How it does feel wind air? Screen is insufficent pressure air! There is no way to help! Sorry!  


RE: Screens On Jet Intakes?

Tue Jun 06, 2000 1:13 pm

Hmm...guess I can't make my fortune selling anti-FOD screens to P&W...back to the drawing board!!    

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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 2:05 pm

lets give out heads a shake here. i can see no one knows any physics, or they forgot to post it here. A 2kg bird flying into a "Screen" that is moving at 150 knots at takeoff/Climbout (think realitvity here). You would need a cement wall to stop it, why do you think that the metal is bend to Kingdome come after a strike? Sorry boys, simply not feasible. Covering the main Cowl with a "Screen" doesn't nessiarly reduce air intake, have a look at the modified J-58's on the SR-71.
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They Are Already In Service...

Tue Jun 06, 2000 2:13 pm

On MiG 29 series aircraft, and have been for some years now. they are deployed during taxi and takeoff regimes of flight, and retracted during normal flight. I've tried to find photos on the web, but these search engines are no help. But trust me, i've seen them in action. they look like plates with small slots that come from the top of the intakes down to match its profile. maybe you all will have better luck locating an image. Helicopters uese defector plates to siphon sand and debris as well, consisting of a plate that causes a sharp bend in airflow into the engine. this sharp turn causes heavier particles to be thrown clear of the intake (because their mass causes their angular momentum to throw them clear) and the lighter less dense fluids (air) is ingested. not practical at high speeds or altitudes though.
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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 2:35 pm

There is a big difference in mass airflow between a Mig-29, SR-71 & helicopter engines and a high by-pass fan engine so I don't believe that system would work.

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RE: Screens On Jet Intakes?

Tue Jun 06, 2000 4:07 pm

Screens would be a great place for ice to collect. When it breaks off guess where it goes. What a horrendous idea.

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