AIM-9B launcg G-limit

[npmm...@gmail.com]

In a number of military aviation books i've read over the years it has mentioned that in a dogfight a fighter couldn't fire an AIM-9B Sidewinder if it was pulling more than two Gs. What i'd like to know is why the -9B was limited to a launch G-load of no more than two Gs?

[Peter Stickney]

It's an interesting question - the missile itself was capable of about 15
Gs worth of turn, so it would seem that the launching it would be a
simple matter of "Point and Shoot". However, it's a lot more complicated
than that - The missile didn't acutally start guiding until the motor
burned out, and the missile was coasting - about 2-1/4 seconds. This was
typical of missiles of this generation, for two reasons - Although the
missile could pull high Gs at speed, at low speeds, it couldn't, and the
wings could stall, and the missile basically fall tumbling to the
ground. The second is that it the missile were guiding off the rail, it
was possible for the missile's proximity fuze to detect the launch
aircraft (Or a nearby wing man) and detonate the warhead, which at best
is a wasted shot, and at worst is shooting yourself down.
OK- so why the 2G limit, and not 4 or 6 Gs? Since the missile wasn't
guiding, the seeker was locked straight ahead - if the target was
crossing the shooter's path at a rate (angle rate from the shooter's
perspective) of more than 2 Gs worth of turn, the seeker would hit its
gimbal limits, and the missile wouldn't track the target. Later missiles
had wider limits on how far the seeker could move, and a wider field of
view for the seeker itself. Addition of SEAM (Sidewinder Expanded
Acquisition Mode), where the seeker was slewed to see the target as it
crossed at higher speeds did a lot to relieve this issue.
SEAM used the aircraft radar to cue the seeker where to look for the
target during the initial fly-out. U.S. Navy Phantoms had, at one point,
a Helmet Mounted Sight for cueing the radar and missle, but it was found
to be not as useful as an auto-acq boresight lock. This may be why the
Western manufacturers (Rather than the Western Press) haven't been all
that interested in jumping on the Russian HMS bandwagon.

--
Peter Stickney
Java Man knew nothing about coffee