F-117 shootdown over Bosnia

. . · Post by **. .** » Fri Apr 21, 2006 12:23 am

the attachments to the sides of the planes are called "Warts". They're obviously only used during peacetime operations.

I Like Myself · Post by **I Like Myself** » Fri Apr 21, 2006 3:30 am

Thanks for sharing that.
Very intersting story.
Was suprised to learn the army dosn't provide a hand held GPS! For 100USD it'd be one of the first things I'd put into a survival kit

Big Pratt · Post by **Big Pratt** » Fri Apr 21, 2006 5:16 am

As to the need for computers, I've heard some RC modellers have made flyable 117's. Don't suspect they have laptops in them for stability. Wink

Laptops? Probably not, but maybe some stabilizing gyros.
Went to an RC show once and most choppers had them.
Also just because it looks like a real 117 does not mean it's aerodynamically the same, nor that it has the CG in the same place.
http://www.hobby-lobby.com/gyros.htm

"Active" prime returns..uh -no.

Why not? If you can enhance a weak return, what makes you think you can't create a return when your actual return is very, very weak. When you start sending them out of phase you can play lots of tricks.

Here's a bit from http://en.wikipedia.org/wiki/Blip_enhancement

blip enhance transmitters that received and amplified the radar signal so that all the escort ship looked like an Aircraft Carrier sized target.

BTW, thanks a lot for the story Hedley, interesting read!
Good weekend to all!

co-joe · Post by **co-joe** » Fri Apr 21, 2006 9:34 am

Good story. Kinda puts bitching about flow control and holds over Toron into perspective.

http://photos.airliners.net/photos/midd ... 029751.jpg
http://photos.airliners.net/photos/midd ... 020152.jpg

FamilyGuy · Post by **FamilyGuy** » Fri Apr 21, 2006 10:58 am

Beleive what you want....try watching MythBusters sometime. The one about how to fool Police Radar was informative.

Think of prime radar energy like waves in water. In order to concentrate the amount of signal the radar receives from a small target, you would need to focus the entire return energy at exactly the correct focal point - while moving - and most likely at a tangent!!!! Little bumps won't do shit. A huge polished steel parabolic mirror might.....but not very aeodynamic and the computing power to aim it....

.

Like zzyjay said, the Tutor, with its brightly polished ALL aluminum rounded fuselage and wings had a horrible prime return - smaller than a goose. Maybe Canadair were the forefathers of "stealth".

I'll find the link on the model stealth, its pretty big.

Lommer · Post by **Lommer** » Fri Apr 21, 2006 2:40 pm

In order to concentrate the amount of signal the radar receives from a small target, you would need to focus the entire return energy at exactly the correct focal point - while moving - and most likely at a tangent!!!!

I think what some people are saying is that you could have active enhancement, i.e. you broadcast a huge omni-directional radio pulse at the same intant you get pinged by the primary pulse. That would certainly increase your radar size. Also, the bumps will definitely have an impact. A lot of the F-117's stealth and most of the stealth on the F-22 come from the composites and paints that they use on the fuselage. These are highly specialized and absorb radio energy, so if you put a flat plate of normal aluminum on top of them that alone would damatically increase the radar return.

As for the Tutor, don't forget that it is an absolutely tiny aircraft, comparable in size to a 172. It's no wonder they had difficulty tracking it on primary.

w squared · Post by **w squared** » Fri Apr 21, 2006 3:37 pm

Let's also keep in mind that regardless of what material you use, certain shapes will return a great radar echo from just about any angle.

Has anyone ever seen a maritime radar reflector? It's simply three circular plates, with slots cut to allow them to overlap.

Given that the angle of reflection is equal to the angle of incidence, two flat surfaces at a 90 degree angle will almost always send a signal back in exactly the direction it came from. It's that simple.

This is why the idea of external "add-ons" to increase the radar cross-section of an F117 makes perfect sense for transitting airspace that is also used by civilians during peacetime. A transponder is good, but having the back-up of ATC being able to get skin paint on you is better.

Spokes · Post by **Spokes** » Sat Apr 22, 2006 10:25 am

You can't trick prime radar - especially the really old stuff that used tubes. Energy out hitting something/anything = energy in and a return generated on the scope. Might be small but its there, unless it's filtered out.

Yes. You can. The older stuff is much easier than newer modern radars. There are a lot of companies that make alot of money desigining such equipment. They also work out stratagies in radar processing to prevent such radarjamming from occuring. Its a vicious circle.

In the case of an older radar, you can transmit a slowly increasing noise return in an attempt to capture the radars automatic gain control. (even the old ones need this). this will raise its detection threashold, and make all targets unseen, while the poor unsuspecting operator does not know he/she is being jammed. In response, some military radar put a switch in to turn off AGC. A simple example, and a somewhat oversimplified explanation, but it illustrates the point.

The F-117 employs a differing strategy to remain invisible. a/c shape, materials etc. The radar return profile of such aircraft are carefully measured to ensure success. These strategies are of course dependant somewhat on target radar operating wavelength. They designe things to counter the most likely air defence radars that this a/c would have to face. Some older radar may operate for one reason or another on different frequencies, and as a result have a bit better luck with detection. This is where that 'older radars work better' myth comes from.

To enhance a radar return, the problem is even simpler. The radar corner reflecter is very effective. A lifeboat with one of these is alot more visible on radar than without. (Many thousand hours as an Aurora sensor operator talking here). While it is possible to build a repeater to enhance a radar signal (some marine beacons have this, also used in some air-air refuling applications I am told), I suspect this would not be employed in this case. A repeater would need an Antenna. An antenna would add considerable to an aircrafts radar cross section, and would no likely be used on such a combat plane. (Unless that is what is in those "bumps" descibed earlier I suppose).

All of this is easily reserched in any text book on the subject. (i.e not highly classified or anything like that)

stupido · Post by **stupido** » Sat Apr 22, 2006 11:03 am

It was not over Bosnia. It was north of Belgrade 70km, town Budjanovci. I would like to know how I can attach a few pictures for you guys.

stupido · Post by **stupido** » Sat Apr 22, 2006 11:30 am

And couple more - F-16s, F-15s, F-18s, Apaches, Predators .......

FamilyGuy · Post by **FamilyGuy** » Sat Apr 22, 2006 12:42 pm

Like I said - beleive what you want, be that in a 'textbook" or US propaganda to scare the enemy with tales of superior hardware or to support excessive military spending - like $100 hammers.

Worked AASR1 many years - commisioned in 1956 - its prime was raw, no fancy anything to trick. No AGC, user controlled just about everything with a plethora of knobs and switches.

Of course that metal reflector would increase the return of a lifeboat! Rubber boats don't reflect much on their own.

Just a little more on the Tutor's poor return, we got a better return from fabric covered gliders!

The theory about the bumps being a "back -up" in case the transponder fails, not likely. The vast majority of radars in the states and even Canada are ISSR - no prime! Normally no transponder means no clearence, but if it fails in flight ATC doesn't rely on sketchy areas of limited prime returns for separation, they fall back to "procedural standards" - commonly called non-radar separation. Even then, it's land at first suitable airport.

stupido · Post by **stupido** » Sat Apr 22, 2006 3:03 pm

Watch these !!!!!

http://www.warinfo.org.yu/f117s.html
http://www.pancevo.co.yu/agresija/avion.html

FamilyGuy · Post by **FamilyGuy** » Sat Apr 22, 2006 11:19 pm

No Watch this....

Maybe not the best defense of my position, but.......

http://rcbar.com/Video/F117.wmv

It did fly until something blew off....

stupido · Post by **stupido** » Sun Apr 23, 2006 7:39 am

FamilyGuy it was a great clip.

Big Pratt · Post by **Big Pratt** » Sun Apr 23, 2006 7:59 am

In that case you'll love this clip.
http://www.bestinthewestjets.com/theate ... 17AWMV.wmv

Amazing attention to detail! Great vid editing too, and gotta love W's voice overlay

Feel sorry for the builders though.

stupido · Post by **stupido** » Sun Apr 23, 2006 8:43 am

I feel bad for those guys. It was a beautiful work. But nothing is perfect.

Lommer · Post by **Lommer** » Sun Apr 23, 2006 10:50 am

Ouch. That's gotta be one of the worst RC-plane-crash videos I've ever seen. I echo stupido's sentiments - it really does make you feel bad for those guys.