From: opus@cbnewsc.cb.att.com (robin.g.kim)
Subject: Re: Getting locks on helos......
Organization: AT&T
Distribution: na
Date: Mon, 14 Sep 1992 00:41:14 GMT
Keywords: helos that won't go down!

In article <BuIvn6.Av7@watserv1.uwaterloo.ca> ptran@watserv1.uwaterloo.ca (Phat H Tran) writes:
>In article <1992Sep13.003125.20216@newshost.lanl.gov> masten@beta.lanl.gov (David A. Masten) writes:
>>In article <BuGDC9.BJG@watserv1.uwaterloo.ca> ptran@watserv1.uwaterloo.ca (Phat H Tran) writes:
>>>In article <nsoloway.716270029@uclagsm> nsoloway@agsm.ucla.edu (Natalie Soloway) writes:
>>>>Well I tried it before and I just tried it again and still I can not
>>>>get locks on helos with a sidewinder...
>>>>As some of you suggested before I tried to turn off my radar and
>>>>switch to sidewinder IR missles but still no dice.
>>>
>>>Adam, I said to use AMRAAMs.  My reasoning was that choppers, especially
>>>something like the Gazelle, won't have a hot enough heat source to 
>>>attract a Sidewinder.  Its radar signature, however, should be quite
>>>inviting to radar missiles.
>>>
>>>Phat.
>>
>>Sorry Phat, you have it bass-ackwards as others have pointed out.  The
>>heat signature of helo engines (turbines) should be plenty big enough.
>>And according to SH, the chopper blades wreak havoc on radar.

This effect is also mentioned in Shaw's "Fighter Combat."

>I full well know about the heat from those turbine engines, Dave.  But
>I have no idea how hot they are compared to jet exhausts, and since 
>Sidewinders in F3 never lock on them, I will assume that they are
>relatively cool.  If the Sidewinder was designed mainly to home in on
>jet airplanes, then its threshold could have been raised to make it less
>prone to confusion from ambient heat.  The chopper engines could very
>well be below this threshold.

If you are talking about S/N, clearly there would be some sufficiently
small range at which the Sidewinder COULD get a lock on a helicopter's
engines.  On the other hand, IR homing missiles are tuned to certain bands
of IR frequencies.  It's remotely possible that helicopter engines produce
IR radiation at greatly different frequencies than jet engines, but I really
doubt it.  I believe all-aspect IR homing missiles differ from rear-quarter
missiles in that they can track a wider range of frequencies (among other
things).

>As to the chopper blades confusing radar, it sounds somewhat logical.
>The spinning blades may cause the reflected signal to strobe.  However,
>from certain aspects, the strobing should be minimal, and the broadside
>of the chopper will return a very strong signature.

Pulse-doppler radar detects differences in velocity.  Although the
cross section of a chopper blade profile is small, the returns it would
generate are more likely to be picked up by the F16's radar.  Also, don't
forget that if the chopper is showing you it's broadside, it's beaming you
so you may not get any useful return from the fuselage at all!

>What's the logic behind turning off your radar when using heat
>seekers?

In 3.0D, at least, this is what you do to get Sidewinder locks on targets
with ECM pods (is this fixed in OFT?).  The logic being that perhaps the
detrimental effect of helicopter rotors on radar tracking are modeled in the
game by pretending it's just a jet using an ECM pod.

>In HFR, I can never get a radar lock on choppers.  In SAM and SAD modes,
>however, the locks are achieved very easily, and the AMRAAMs can be
>used very effectively to rid the sky of these pests.  Don't even bother
>with Sidewinders when you stumble upon a helicopter.

Has anyone gotten gun kills on helicopters?  The closing rate is so fast,
I can never get a shot lined up.

Rob
ihlpy!opus@att.att.com