F-4 chaff/flare loads

Juvat wrote in message . ..
I just flipped thru my notes from a 1984 course at TAWC, and can't
find the reference. I only got to keep some of them. The course had
guys from every tactical jet in USAFE, TAC, and PACAF. The question
was raised about the effectiveness of photo-flash carts versus IR
missiles during an IRCM lecture.

The short answer was they're ineffective due to the lack of sufficient
coverage of the IR spectrum (not enough heat), plus they're ejected
above and to the side before "blooming" which probably puts them
outside the seeker's centroid (depending on the missile's range from
the RF-4). But not a problem with A-10s' flare dispensers out near the
wingtip.


I can totally buy that the eject profile is wrong, and that they get
out of the track beam of the seeker before they bloom. That is one of
the major design issues with IR counter measures flares, getting them
to heat up quick, without being explosive. However, IRCM flares are
JUST short of "explosive", they have a very rapid velocity factor. If
you have ever listened to them from outside the AC, say on the ground
under the AC, they make a very distinctive "pop" on ignition, a pop
that can be heard over a pair of engines in reheat.

I mean, if you go to this page:
http://www.fas.org/man/dod-101/sys/missile/row/sa-7.htm
You will see that the track "beam" of a period weapon, in this case
the SA-7b, is only 1.9 degrees wide. This is the instantaneous field
of view. That means that the flare would only have to move half this
value, or .95 degrees, to be out of the beam of the weapon (assuming
the weapon is tracking the aircraft). Lets figure a beam shot (yes, I
know, not with a 7b), at mid envelope range, say 2000 yards, 6000
feet. At that range 1 degree (17.5 mils) is about 105 feet. Lets
assume an aircraft speed of about 450 knots. That means the aircraft
is moving about 750 feet / sec. Or, the flare must come up to a high
enough energy state to mask the aircraft in less than 0.15 seconds, or
150 millisecond.

As far as the photo-flash flares having "not enough heat", I can see
someone saying that, in fact I have heard similar quotes from supposed
knowing individuals, but the physics just don't work that way. Less
heat means more shift to the red end. That is why something is
described as being "white hot". So, what it amounts to is, if it is a
pyrotechnic device (and these are) it will emit at least as much in
the IR as in the visible. Infra Red emissions happen at a lower energy
state then visible light emissions. So that even when it has burned
out, and is not issuing very much visible light, it will still be
emitting in the IR. This is a generalization, but a good one for
flares.

A high school physics example here. Take a DC light bulb, say a 12
volt car lamp. Turn down the voltage getting to the lamp, the lower
the voltage, the redder the lamp will glow. Eventually the lamp will
no longer put out visible light, but will still stay hot to the touch.
It is still putting out IR, but the energy state is lower, too low to
produce "white" light.


We watched a couple AVTR clips showing various IRCM techiques against
AIM-9P and L seekers and some foreign made seekers. The tests by the
guys at TAWC concludeded the photo-flash didn't decoy any seekers. And
there were remarks like, "We'd really like to show you some more neat
stuff, but you guys don't have need to know."

Additionally RF-4s had specific IR flares manufactured for their cart
breeches, not simply photo-flash carts modified to bloom early and
burn longer. I know they worked against the AIM-9 from DACT with the
MS or AL ANG.


Yes, IR flares are specifically designed, not an adaptation of other
types of flares. The point of what I am saying is that photo-flash
flares will have some signature in the proper IR bands, but without a
doubt, it could be made better.



I had an interesting LOWAT sortie were I tapped an MC-130. I had
gotten a satisfactory weapons check after takeoff (my Lima's seeker
tracked my wingman's exhaust). I managed to trap the MC-130 at my 12
o'clock thru superior airmanship and cunning (okay a single side
offset intercept). When I uncaged the seeker head it literally started
nutating in ever increasing circles and sailed way off the Herc. No
"visible" flares were noted (none on my AVTR), but that Lima just
couldn't lock-on to the Herc's engines. My wingman had the same
experience, and we could track and uncage the seeker against each
other after the Herc engagement. Magic...

Juvat


lol...magic...magic with some kind of ALQ designator ;-) And that is
old tech, you should see some kind of DIRCM at work.

Token