P-51D Rear Warning Receiver AN/APS-13

[effte]

Sure. You can shoot down UAVs with sidewinders, a P-51 is bigger and hotter. Not as hot as a jet engine though.

 

You can shoot down a deep-frozen elephant at 0K with a Sidewinder, provided it falls through the air just in front of your pylon and you time it right. :D

 

I'd expect early AIM-9s to have trouble locking onto a piston job doing anything but full blast with flames out of the exhaust stacks. Later all-aspect models, which can even lock onto the warm(er) leading edges of the wings, shouldn't have problems homing on a piston aircraft... but should have a much harder time locking than it would have for a dual blowtorch in full reheat.

 

It's never either/or. :)

 

Edit: Not sure that thing is what you want though. http://en.wikipedia.org/wiki/Flensburg_(FuG_227)

Edit II: Just for reference, as it was an interesting read. http://www.hawkertempest.se/ElectronicWar.htm

Edited February 2, 2012 by effte

[GGTharos]

I'd expect early AIM-9's to have trouble locking onto anything, but they got better rather quickly.

[sobek]

Isn't that pretty much a 'depends' thing? I mean, against the clear blue sky, any aircraft is going to stand out like a christmas tree as long as the seeker isn't so hot that it's SNR is completely down the drain.

[Eddie]

Is the P-51 hot enough for the sidewinder to lock-on to it?

 

More than 'hot' enough. Current generation SRAAMs will happily track a glider, slightly older ones like the AIM-9M will have no real issues with a piston powered aircraft. The only difference you'll see compared to a jet is, possibly, that you won't obtain a lock from as far away.

[VincentLaw]

For those arguing about jet vs piston: I tried flying a winter mission with four aim-9 missiles in the A-10C against T-80 tanks, which are powered by turboshaft jet engines. I slaved the aim-9 seeker heads to the target pod and locked the target pod on the tanks. No matter how close I got the the tanks or which side I approached from, the aim-9s would not lock on the tanks. I am assuming the T-80 gets hotter than a P-51, but of course this does not prove anything about what would happen in real life between the two.

[Speed]

Isn't that pretty much a 'depends' thing? I mean, against the clear blue sky, any aircraft is going to stand out like a christmas tree as long as the seeker isn't so hot that it's SNR is completely down the drain.

 

Correct, but noise is both in the sensor and in the background, and the target would need to stand out enough above both of those to get a lock.

 

Some missiles (more often SAMs I think) even have dual spectrum seekers that can detect the UV shadow of an aircraft against a blue sky... good luck evading those.

[Speed]

For those arguing about jet vs piston: I tried flying a winter mission with four aim-9 missiles in the A-10C against T-80 tanks, which are powered by turboshaft jet engines. I slaved the aim-9 seeker heads to the target pod and locked the target pod on the tanks. No matter how close I got the the tanks or which side I approached from, the aim-9s would not lock on the tanks. I am assuming the T-80 gets hotter than a P-51, but of course this does not prove anything about what would happen in real life between the two.

 

Against a cool background a running tank would definitely be hot enough to be lockable with modern IR AAMs. The problem is, ED didn't really program that kinda stuff into the sim yet, so while I applaud your effort, it was futile. ;)

[jib]

Aww the P-51 gets a Radar Warning Receiver and the Ka-50 Doesn't :doh:

[AlphaOneSix]

It's not a Radar Warning Receiver, it's a Rear Warning Receiver.

[VincentLaw]

Actually, good point. I wonder if that means the A-10 RWS will pick up the P-51. I am guessing the answer is yes.

[EvilBivol-1]

It's not a Radar Warning Receiver, it's a Rear Warning Receiver.

To be completely precise, it's a Rear Warning Radio. Meaning, it's not a passive receiver, but a small active radar. :)

http://www.duxfordradiosociety.org/restoration/equip/aps13/aps13.html

[EtherealN]

Actually, good point. I wonder if that means the A-10 RWS will pick up the P-51. I am guessing the answer is yes.

 

Depends entirely on what it's made to classify as a threat. The A-10 RWR might just classify that thing as a weird radio beacon and ignore it, meaning it might pick it up fine, but won't tell you about it. Besides, why inform you of a non-hostile emitter that only happens when the offender is heading away from you? :P

[EtherealN]

Aww the P-51 gets a Radar Warning Receiver and the Ka-50 Doesn't :doh:

 

Quite the opposite really. A radar warning receiver actually detects hostile emitters. The P-51D has nothing that can do that. What this thing is is just to notice that "something is back here". As was mentioned earlier - it's a glorified proximity fuze but with no bomb attached to it. :)

[Rainbowed]

Beautiful. There is a reason you guys win all those awards. Any chance you guys can model all of Europe from the 1940s too? JK

Im sooo totally with you

[PeterP]

To be completely precise, it's a Rear Warning Radio. Meaning, it's not a passive receiver, but a small active radar. :)

http://www.duxfordradiosociety.org/restoration/equip/aps13/aps13.html

:D So it will warn me also in a narrow parking slot from the things that are behind me?!

[sobek]

Correct, but noise is both in the sensor and in the background, and the target would need to stand out enough above both of those to get a lock.

 

Are there any athmospheric conditions where the sky would not give you a very good SNR against an airplane (visual moisture aside)?

[GGTharos]

Yep, moisture attenuated IR SNR, visible or not.

[NineLine]

Maybe when the nay-sayers see the detail this bird gets from ED they wont be so down on it, I cant wait... are we there yet? :)

[Speed]

Are there any athmospheric conditions where the sky would not give you a very good SNR against an airplane (visual moisture aside)?

 

Good question, several times I've tried to find a good answer to what the equivalent black body temperate of the blue sky background was. Finally found a good answer from this source: minds.wisconsin.edu/bitstream/handle/1793/7648/Proyecto.doc

 

The equivalent blackbody sky temperature of (2.4.2) accounts for the facts that the atmosphere is not at a uniform temperature and that the atmosphere radiates only in certain wavelength bands. The atmosphere is essentially transparent in the wavelength region from 8-14 m, but outside of this “window” the atmosphere has absorbing bands covering much of the infrared spectrum. Several relations have been proposed to relate Ts for clear skies to measured meteorological variables. Berdahl and Martin (1984) used extensive data from the United States to relate the effective sky temperature to the dew point temperature, dry bulb temperature, and hour from midnight t by the following equation

 

Where Ts and Ta are in degrees Kelvin and Tdp is the dew point temperature in degrees Celsius. The experimental data covered a dew point range from –20 C to 30 C. The range of the difference between sky and air temperatures is from 5 C in a hot, moist climate to 30 C in a cold, dry climate [Duffie and Beckman, 1991].

 

Anyway, plugging these results into Excell, I see a similar range of values as claimed.

 

So, lots of humidity is going to kill you (as expected), not only in that it reduces the delta-T between the target and the background sky, but also it attenuates IR radiation.

 

It seems fairly reasonably then to expect the equivalent black body temperature of the blue sky background to be an average like 20 degrees K cooler than the outside air temperature. At sea level, I think. Dunno about higher up. Anyway, kinda happy about those numbers, that's about what I expected it to be.

Edited February 3, 2012 by Speed

[GGTharos]

Generally speaking a look-up shot (Away from they sun, too) is prefferable, so they sky will pretty much always give you a better SNR than just about any other alternative, obviously humid air/clouds aside.

 

Modern weapons are at the point where the ground clutter only reduces sensor range though. An AMRAAM can directly hit a low-flying cruise missile that's only about twice the diameter of itself for example. Similarly, a stinger missile can also be used against a cruise missile, and it doesn't have the most modern seeker around either.

 

Heat seekers with even more modern sensors (ie. IIR) will track anything that can provide contrast and they'll often be immune to passive countermeasures - and ground clutter (though again, useful sensor range can be easily reduced by ground clutter).

 

All these can still be vulnerable to multi-path issues, such as for example, heat reflection from water is there's an aircraft flying quite low, etc.

 

Are there any athmospheric conditions where the sky would not give you a very good SNR against an airplane (visual moisture aside)?

Edited February 3, 2012 by GGTharos

[Freelansir]

Being new to DCS P-51 I am happy to see this feature included.

 

However, has anybody actually have it warn you of somebody behind you ?

 

Thanks,

 

Freelansir

btw, thanks to Foul Ole Ron for answering one of my questions, but I wonder what the "Warn (0%)" means under my name. I hope I haven't violated something

[NineLine]

Being new to DCS P-51 I am happy to see this feature included.

 

However, has anybody actually have it warn you of somebody behind you ?

 

Thanks,

 

Freelansir

btw, thanks to Foul Ole Ron for answering one of my questions, but I wonder what the "Warn (0%)" means under my name. I hope I haven't violated something

 

If it says 0% you dont have any warnings :)

[Merlin-27]

Being new to DCS P-51 I am happy to see this feature included.

 

However, has anybody actually have it warn you of somebody behind you ?

 

Been warned plenty of times! ...by the An/APS-13, that is. It works for sure, as long as they are fairly close and you are well above any ground interference.

[White Owl]

Being new to DCS P-51 I am happy to see this feature included.

 

However, has anybody actually have it warn you of somebody behind you ?

 

Up 'til now, I completely forgot this piece of equipment existed, so haven't ever turned it on. :huh: