Mig 29 - question about the intake covers

I see them now, I just wasn't getting it before.

Originally posted by Zaphod58
oh of course not. It's been done for a long time now. Just the US doesn't use something like the MiG-29 does, with the intake covers

The F-117 has a cover over the intakes, but they aren't retractable. Sounds like a good idea though doesn't it? One of the worst things that can happen to a jet engine is to pick up some debris.

I dont know for sure, but those may also open in flight when extra air is needed for the engines.

Check out pic :

external image

[edit on 4-7-2005 by Stealth Spy]

Not the case. Inflight, engine demand has nothing to do with the position of the louvers. They are merely spring-loaded doors and there is no system controlling their position. Their position is due to pressures in and around the air intakes. Especially at high angles-of-attack, you'll see the louvers open and close. The louvers are also independent of each other. Some of the louvers will be open and some closed at high angles-of-attack. Sufficient air is provided through the main air intakes to keep up with engine demand.

I am also wondering how exactly those covers work on the F-117. they look like a mesh of some sorts? also if was effective in its role why hasn't it been added to other planes? some sort of problems have happened from them im guess otherwise as i just said they would be more widely used right?

From what I've been told of the F-117 intake covers, they are there to help keep radar off the fan blades of the engine, not to keep debris out. The engines are high enough that FOD is less of a factor with the 117, but radar hitting the fan section of the engine would be a big increase in the RCS of the plane.

so that reasoning Zaphod would mean that adding it to other planes like the F-22 is that the compressor blades aren't a problem?

You have to look at the shape of the intakes, the shape of the tunnel leading to the fan blades, and the size of the intakes. There may also be things done inside the intake that we can't see to defeat radar. Again, I'm just going by what I was told about the screen on the F-117. With the placement of the intakes on it you really don't have to worry about FOD going down the engines, unless someone stands there throwing things at it. They're up too high for FOD to have been the main reason for the screens.

More about the F-117 intake screens.

"The purpose of these gratings is to prevent radar waves from traveling down the intake ducts and reaching the whirling blades of the turbofans, which would tend to produce large echoes. This works because the spacings between the grids on the grating are smaller than the wavelengths of most radars. The grating is covered with RAM, which helps to reduce the reflections even further. The small fraction of incident radar energy which does pass through the grating is absorbed by RAM mounted inside the duct. Unfortunately, these gratings also restrict airflow to the engines, so a large blow-in door is fitted atop each engine nacelle to increase airflow to the engine during taxiing, takeoffs, or low-speed flight. Ice buildup on the intake gratings is a persistent problem, which tends to clog the rectangular openings and restricts the airflow even further. In order to clear the ice, the F-117 employs a electrical heating system which removes ice during flight. A light on either side of the fuselage illuminates the intake covers so that the pilot can watch the deicing operation during night flights."

www.csd.uwo.ca...

The F/A-22 has both of its intakes curving in an S form so that radar waves are broken up instead of going through.

Thanks for the info guys! lots of help. so the extra intakes used by the 117 are to off set the diverted airflow from the mesh covering. also west point the 3 curve employed by the 22 looks to be placed also on the 35 JSF as well. Anyone know about the B-2 I've seen large extra intakes on the top of the plane as well. would this be because of the shape of the plane and the lack of air getting into the intakes? from what i can tell it doesn't use any mesh like the 117.

If you look at pics of the B-2 on the ground it has the same system as the -117 except on the -117 the door opens inward, and on the -2 they open upward in a gull-wing design.

Originally posted by intrepid

Originally posted by Hockeyguy567
A bit jealous, aren't we Stealth Spy?

Was that necessary? :shk:

Yes.

fulcrumflyer or anyone else, I was wondering why the mig has a chute deployed in that picture that jra posted? Is it used to land on very short runways or something? Why would they need a chute on a regular length jet runway?

A bit jealous, aren't we Stealth Spy?

Hockeyguy, your signature asserts you are russian and you post nothing but third rate filth about russian weaponry and what not. What's the real deal ?

how easy it would be for me to claim to belong to a country that i actually dont belong to and post rubbish about it ?

And yes who does not envy money and wealth ?...was'nt it for the same reason that you ran away to where to are ?

Hockeyguy, your signature asserts you are russian and you post nothing but third rate filth about russian weaponry and what not. What's the real deal ?

Stealth Spy, I know what I'm talking about buddy, I'm not the one who constantly posts BS, like you. You need to stop getting your information from biased sites and start to subscribe to AvWeekly and Jane's (knowing people also helps too, where I get some of my info from.) I mean aren't you aware that most of what you say gets shot down? And that's not just from me, just look around the forum.

Off the record, I moved to the US 8 years ago from Russia, and I can tell you right now, the US is a far better place to live.

warpboost,
The drag chute is obviously used to slow the jet down during landing roll. Its use was mandatory in the Luftwaffe on runways less than 7000 feet. The chute is very effective and saves a lot of wear and tear on the brakes. No-chute landings in the MiG-29, even on very long runways, run the risk of overheating the brakes. If the brakes get too hot, there are lead plugs in the wheels that will melt and relieve air pressure. Remeber, air expands when heated and there is a risk of explosion if the wheels and tires get too hot. The main landing gear and the nose landing gear all have brakes. Having brakes in the nose landing gear is abi-normal in the jets I've flown. Bottom line - the Fulcrum's brakes ain't all that good. The drag chute is. It'll stop the jet on the proverbial dime.

We had a Russian IL-86 come in one time with a VIP on board to observe an exercise, and after they parked the first thing they wanted to do was have the fire department spray down the wheels to cool the brakes off. Everyone there looked at them like they were insane, but apparently they do this all the time at their home base. Water+hot brakes= Bad Things.

Yes water on hot brakes is a very bad idea, specaily when most aircraft wheels and brakes are made from magnesium and reacts with water when they are hot.

ALso you guys are talking about 2 very different intake systems. The 1 system is for protecting the engines from debris, the other part of a intake system is for helping airflow during MACH speed.



[edit on 6-8-2005 by ULTIMA1]

[edit on 6-8-2005 by ULTIMA1]

[edit on 6-8-2005 by ULTIMA1]

Originally posted by ULTIMA1
Yes water on hot brakes is a very bad idea, specaily when most aircraft wheels and brakes are made from magnesium and reacts with water when they are hot.

[edit on 6-8-2005 by ULTIMA1]

I bet cryo treated brakes could handle water. I remember watching some road racing on TV a while back that was SCCA or Trans Am and they had water mister systems for the brakes I remember the announcer saying the rules state everyone only gets one tank of water and how you use it is up to you