Fighter Combat - Tactics and Maneuvering

FIGHTER WEAPONS 53
rocket-powered vehicles increases when they are operating at higher altitudes.
Although higher altitude reduces jet thrust, drag usually decreases
even faster, particularly for supersonic vehicles, up to about the level of the
tropopause. For rockets, thrust usually increases with higher altitude. This
in conjunction with lower drag results in significant improvement in range
with increasing altitude. Figure 1-10 gives an approximation of the effect of
altitude on a rocket-powered missile's maximum aerodynamic range
against a co-altitude target, using sea-level performance as a standard.
Similar variations can be expected in both rear- and forward-quarter
launches. Note that missile aerodynamic range increases dramatically
with altitude, particularly at the higher levels. Range at 20,000 ft above
mean sea level (MSL) can be expected to be about double the sea-level
value, with performance doubling again by 40,000 ft. For look-up or lookdown
shots, range is closely related to the median altitude between the
shooter and the target. Look-down shots, however, are more likely to be
limited by factors other than aerodynamics.
When operating against fixed SAM sites, low altitudes can offer some
benefit. Earth curvature and terrain masking provided by hills, trees, etc.,
may limit target acquisition range even below aerodynamic range. Ground
clutter is also a problem for radar-controlled SAMs, but it can be reduced
by Doppler techniques and alternative optical guidance systems. When
considering very low altitude operations, the pilot must balance the benefits
against mission objectives and the greater effectiveness of small arms,
anti-aircraft artillery (AAA), and very short range SAMs. Within their
operating envelopes most missiles can be expected to be more maneuverable
at low altitude because of better aerodynamic control. Low-level
operations may also limit the usefulness of the fighter's own offensive
weapons system.
Figure 1-10. Effects of Altitude on Missile Range