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  #1  
Old 03-19-2017, 11:07 AM
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Belarusian airforce Mig29 and Su25 are landing on Minsk-Mogilev highway.


Has the USAF or Navy ever practiced anything like this in the states?
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Old 03-19-2017, 11:12 AM
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And just because it is cool lol
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Old 03-19-2017, 11:30 AM
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Originally Posted by Ryan S. View Post
Has the USAF or Navy ever practiced anything like this in the states?
Not without great risk to American fighter engines. FOD being sucked inside the intake issue.

What most Americans do not know is, Russian fighters are like the AK-47, you can drop them in mud and they will still fire without fail. Russian fighter engines are designed to suck in a certain amount of FOD whereas an American fighter and its precision tolerances, the engine is done. US fighters need super-clean, FOD-free runways.
US Navy carriers, before air ops, deck crews will "walk the FOD", shoulder to shoulder in a straight line looking for debris.
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Old 03-19-2017, 11:39 AM
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Not without great risk to American fighter engines. FOD being sucked inside the intake issue.

What most Americans do not know is, Russian fighters are like the AK-47, you can drop them in mud and they will still fire without fail. Russian fighter engines are designed to suck in a certain amount of FOD whereas an American fighter and its precision tolerances, the engine is done. US fighters need super-clean, FOD-free runways.
US Navy carriers, before air ops, deck crews will "walk the FOD", shoulder to shoulder in a straight line looking for debris.
Has it always been this way? Im wondering if they ever practiced stuff like this in the 50s with Sabre Jets or something just in case.....
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Old 03-19-2017, 11:54 AM
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Originally Posted by Ryan S. View Post
http://www.youtube.com/watch?v=gttwL854cR4

Has the USAF or Navy ever practiced anything like this in the states?
Maybe not in the States but IIRC they did in Europe during the height of the Cold War (80's).

Also just last summer
http://www.cnn.com/2016/06/23/politi...order-estonia/
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Old 03-19-2017, 12:44 PM
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Originally Posted by RacerX_GTO View Post
Not without great risk to American fighter engines. FOD being sucked inside the intake issue.

What most Americans do not know is, Russian fighters are like the AK-47, you can drop them in mud and they will still fire without fail. Russian fighter engines are designed to suck in a certain amount of FOD whereas an American fighter and its precision tolerances, the engine is done. US fighters need super-clean, FOD-free runways.
US Navy carriers, before air ops, deck crews will "walk the FOD", shoulder to shoulder in a straight line looking for debris.
How can their engines be designed for that? I know some of the Russian jets close off the turbine intakes and open a second set of intakes mounted on top of the wing to reduce taking in debris, but I've never heard they can otherwise take in more directly by design...
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Old 03-19-2017, 05:44 PM
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Common in Sweden... SAAB fighters are often hangared off highways, even 2 lane highways in the woods.


From that vid, it looks like the only planes exposed to FOD are the following plane. The lead take off has clear air.
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Old 03-20-2017, 03:39 AM
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Maybe not in the States but IIRC they did in Europe during the height of the Cold War (80's).

Also just last summer
A-10s make rare highway landing near Russian border - CNNPolitics.com
Yes, quite a number of times, especially A-10s on German Autobahns...

At the risk of repeating myself, the 1970's were pushing us slightly on the paranoid side, more so when you were raised on the french/german border, because, as said one of my teachers in history: from the czech border, which was the limit of the iron curtain, to our homes, the warsaw pact tanks were exactly at one day drive...

But boy, what a treat the seventies were for a young aviation fan; want to see aeroplanes? Just walk into the garden and wait, something will come in the sky soon. And as there were almost no altitude limitations, you saw them in large dimension; some of these guys were flying really low, especially the Canadians with their overall-green CF-104s (wraparound camouflage)...somehow, I miss those days.

Rgds
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Old 03-20-2017, 05:57 AM
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Back in the 80s.

A-10s in S. Korea as well. In fact, many of their highways have sections designed precisely for that, with "pads" at each end of the landing zone for refueling and re-arming. These pads are often blocked from view by rolling gates and large signs.
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Old 03-20-2017, 10:45 AM
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But boy, what a treat the seventies were for a young aviation fan; want to see aeroplanes? Just walk into the garden and wait, something will come in the sky soon. And as there were almost no altitude limitations, you saw them in large dimension; some of these guys were flying really low, especially the Canadians with their overall-green CF-104s (wraparound camouflage)...somehow, I miss those days.

Rgds
A couple yrs ago while in Moscow having lunch with some colleagues, we were reminiscing about the good ol days of the cold war and how much fun it was working in aerospace at the time.
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  #11  
Old 03-20-2017, 11:08 AM
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A couple yrs ago while in Moscow having lunch with some colleagues, we were reminiscing about the good ol days of the cold war and how much fun it was working in aerospace at the time.
I was living in the eastern tip of France during the seventies; we were surrounded by airbases; USAF was not far in Bitburg, Ramstein, etc...the Canadians were at Bad-Solingen, Zweibrücken, etc...Belgians were not that far either, not to mention the Luftwaffe, and the French too...
During some days, when there was real aerial activity, you could see 50 aircraft per day: F-4, F-104s, Mirages, and later on F-16, F-15, A-10...to say nothing of C-130s, etc...
After 1990, well...let's say one per week? At most.

Last time I have seen something really truly extraordinary was when I climbed on of a train in Hyères, Provence, late in an evening in august 1994 and by chance was just under the french "aeronavale" rehearsing their aerial figures for the 50th anniversary of the Provence landings. Their F-8 Crusader where really old at the time, but absolutely stunning to Watch.

Rgds
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Old 03-20-2017, 11:17 AM
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I believe the Swiss do it regularly. Or was it the Finns?
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Old 03-20-2017, 11:24 AM
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I believe the Swiss do it regularly. Or was it the Finns?
The Swedes are know for it, but I believe the Finns do it as well.
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Old 03-20-2017, 11:24 AM
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I believe the Swiss do it regularly. Or was it the Finns?
The swiss DID it regularly; I seem to recall that they stopped to do it in 1991. Perhaps the F-18 is less adapted to this than was that most elegant classic aeroplane, the Hawker Hunter....

https://www.youtube.com/watch?v=jHwwAV12TIA

Rgds
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Old 03-20-2017, 11:45 AM
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A-10 operating off a dry lake bed.

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Old 03-20-2017, 11:55 AM
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...even the C-130 did it: see the first ten seconds...

https://www.youtube.com/watch?v=Qx7Meo7w-pY

Rgds
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Old 03-20-2017, 04:39 PM
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Originally Posted by RacerX_GTO View Post
Not without great risk to American fighter engines. FOD being sucked inside the intake issue.

What most Americans do not know is, Russian fighters are like the AK-47, you can drop them in mud and they will still fire without fail. Russian fighter engines are designed to suck in a certain amount of FOD whereas an American fighter and its precision tolerances, the engine is done. US fighters need super-clean, FOD-free runways.
US Navy carriers, before air ops, deck crews will "walk the FOD", shoulder to shoulder in a straight line looking for debris.
Turbine engines aren't like AK-47's, ALL turbine engines are susceptible to FOD. Russian engines aren't any different than ours when it comes to FOD. The stuff about them being more robust is just a lot of hooey, likely written by folks who don't have a clue...

The aerodynamics dictate the shape of blading and the blading tolerances have nothing to do with FOD resistance. Our engines are designed to stay on the wing longer and FOD causes blade damage that limits low cycle fatige life. Since we don't want to pull an engine for FOD, our guys are more diligent about FOD because of the costs involved, not because our engines are less tolerant. Our operational scenario is very different than theirs and costs enter into it. If you damage a blade and end up with an LCF problem that reduces your life to say 500 cycles, but your TBO is 400 mission cycles anyway, then it isn't a problem, you just pull the engine and replace the blade at overhaul. If your engine life is 2000 cycles a FOD event that results in a 500 cycle life is a big deal, because you're now pulling an engine because of that. The Russians had shorter TBO's so it wasn't that FOD did less damage, it's just that it wasn't as big a deal since you're going to do a tear down sooner so you can accept more damage before it starts to be a big deal.

When a blade encounters FOD they get damaged. Period. The Russians don't design their engines any differently than ours from that standpoint. Blade thickness near the leading edge is what determines FOD resistance, but the reality is that if you try to do anything to try to make the leading edges thicker, the aerodynamics goes in the toilet because of shock losses.. If you try to make the blade thinner your stress levels go through the roof and you'll have LCF problems before you have an issue with FOD..

I designed fan blades at P&W for the TF30 and F100 and F401 and shock losses and flutter drove the design process. Bottom line is that there is very little room in the design space for trying to make engines more FOD resistant given the aerodynamics that fighter engines require.

The Russians understand that too and the Mig-29 has doors that close the inlets during takeoff. This is a feature that is dictated by their desire to use the aircraft in places where there might be more FOD. What is clear is that the engines in the 29 can't stand any FOD either or wouldn't have gone to all the trouble to put in a heavy and expensive system like that to prevent FOD damage if they were robust enough to withstand that damage. The Russians use doors, we use FOD walks, different ways to accomplish the same thing. We'd rather not carry that extra weight, they want to operate in areas where there is more FOD. Different strokes for different folks.

ALL military engines operate with some FOD damage and there are procedures to address that damage in the field. They all have nick a blend limits specified once the engines are fielded. I WROTE the nick and blend limits for the F100 way back in the mid 1970's. We specified how much blending could be done on each blade and how many blades could be damaged before you lost performance. Our allowables for nick and blending weren't as big as the early engines because we had higher blade stress, but that was dictated by the aerodynamics as we went away from the multiple circular arc airfoils that were common in earlier engines and we developed arbitrary blade design codes that could work backwards to define the airfoil you wanted to by first specifying the flow field you wanted (UDO300). We modified the airfoil shapes and then ran stress analysis to set the new limits and it was amazing how much you could allow on a blade if you knew it was coming out of the engine the next time it was in out of the airplane.

For a little bit of history, if you go back to the mid to late 70's the USA was working on "high through flow" aerodynamics and higher stage loadings, wider chord blades and higher pressure ratios per stage and higher tip speeds..... Aerodynamics that are commonplace today... I was looking at a cross section of an early HTF test rig and my counterpart at Wright Field mentioned that "the Russians are already doing this" and he said that "the FTD guys are good"... (FTD = Foreign Technology Division, the guys at the field that keep tabs on the other guys)... ie... we stole that stuff from the Russians...

The bottom line being that our aerodynamics aren't any different than the Russians and haven't been for the last 30 years or so... We all have to bend the same air and at some point the physics takes over and the differences become pretty small.. How you operate and how you contend with FOD are different, but the damage is the same..
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Old 03-20-2017, 05:53 PM
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The Russians want to be able to operate from unimproved airstrips. To that end the SU 27, for example, has "flaps" or more like barn doors located in the air intake for the engines. During the takeoff run these doors are closed from the front and open on top of the wing, which means that they are pulling air from above the wing-hence cleaner air with less FOD. When airborne the doors revert to a position whereby the engines pull air directly from in front. A genius solution for dirty airstrips.
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Old 03-20-2017, 06:11 PM
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Quote:
Originally Posted by beast View Post
A-10 operating off a dry lake bed.

www.youtube.com/watch?v=zi5_bcb08o0
The primary reason for the high-mounted engines.
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Old 03-20-2017, 06:16 PM
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And Singapore F-15s and F-16s:

Watch F-15 and F-16 Fighters Land on a Highway
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