All I was trying to say is that an aircraft will lose maneuverability as it gains altitude.

In addition, air breathing engines produce less thrust the higher up they go for the same basic reason (decreased air density and the resulting decrease in mass flow rate through the engine). Rocket motors are less prone to atmospheric effects since they carry their own oxidizer. They are only affected by the under- or over-expansion of exhaust gases exiting the nozzle due to changes in atmospheric pressure.

Think about the way the shuttle's solid rocket boosters' exhaust plumes look just before they run out of fuel. That's over-expanded flow and is an off-design condition if I remember correctly. As far as I know, this is the only significant atmospheric effect on a rocket motor's thrust output.

I think I got a little bit off track there. The simple point I was trying to get across is that any aircraft is less maneuverable at high altitude vs. low altitude. The same is likely the case for a missile too, unless the missile is somehow more maneuverable at speeds it can only reach at high altitudes (i.e. Mach 3-4+). I doubt that is the case though.

Missiles simply perform better in terms of range and energy potential at high altitude because there's less drag, but I doubt they can turn faster/tighter up high than down low.

Anyway, it's a well known fact that A-A missiles are much more likely to hit a high-flying target than a low-flying target...

especially when launched from high altitude and high speed (F-22 supercruising for example). This is because a missile (when fired within reasonable parameters) has more of an energy-maneuverability advantage on a high-flying aircraft than vice-versa.

Another thing one has to consider in the performance equation is weight. A missile doesn't weigh very much and has a huge T/W ratio. Even after rocket motor burnout, it can pull 20G turns given enough kinetic energy. And it pulls these high G turns in an incredibly tight turning radius.

Guys

Does anyone know whether A-A missiles (such as the AIM-120, AIM-9, R-77 etc) can actually turn at all above 40,000ft with those tiny fins?

I read a lot of the answers given in this thread but most of you are getting away from how a missle really works after weapon release. First of all I'm going to be very generic here and talk in general about IR missiles, so I will not be talking about any thrust vectoring missiles.

Most A/A missles use what we call "proportional navigation guidance", which means it causes the aircraft to fly to a point to intercept the target rather then simply chase a target. When the missile is launched the missile's flight continually changes until the target is destroyed or aerodynamic drag slows it down and the projected collision point becomes further ahead of the target, in other words "the missile simply can't get from here to there", not enough umph, no more gas, gas gauge on empty..lol

The missle homes in on the IR energy emitted from the target. The IR energy gathered by the seeker and is processed by the internal electronics of the missile into tracking and guidance commanded signals. These signals are then converted into fin commands which steer the missile to the target (so yes the fins do steer the missile).

So when the missile leaves the aircraft generally a tracking error has been developed between the missile heading and the desired flight path to the target. The missile is continuosly trying ti minimize this tracking error. The missile motor is burning to accelerate the missle and after rocket motor burnout it is then simply gliding to intercept the target. Now remember the misslie does not have to hit the target it just needs to be close enough to sense energy reflected back by to the missiles optical target designators. But of course I'll take a direct hit any day.

Now some missiles are better at different firing aspect angles, some are better in a forward hemisphere shot, some are better at look down, some are better at a rear hemisphere shot, and some are what we call all-aspect. So to answer the question above, yes those tiny fins do turn the missile whether its at 40,000 ft or 10,000ft.

Cheers,

ViperDude