Fighter Combat

FIGHTER WEAPONS 53rocket-powered vehicles increases when they are operating at higher altitudes.Although higher altitude reduces jet thrust, drag usually decreaseseven faster, particularly for supersonic vehicles, up to about the level of thetropopause. For rockets, thrust usually increases with higher altitude. Thisin conjunction with lower drag results in significant improvement in rangewith increasing altitude. Figure 1-10 gives an approximation of the effect ofaltitude on a rocket-powered missile's maximum aerodynamic rangeagainst a co-altitude target, using sea-level performance as a standard.Similar variations can be expected in both rear- and forward-quarterlaunches. Note that missile aerodynamic range increases dramaticallywith altitude, particularly at the higher levels. Range at 20,000 ft abovemean sea level (MSL) can be expected to be about double the sea-levelvalue, with performance doubling again by 40,000 ft. For look-up or lookdownshots, range is closely related to the median altitude between theshooter and the target. Look-down shots, however, are more likely to belimited by factors other than aerodynamics.When operating against fixed SAM sites, low altitudes can offer somebenefit. Earth curvature and terrain masking provided by hills, trees, etc.,may limit target acquisition range even below aerodynamic range. Groundclutter is also a problem for radar-controlled SAMs, but it can be reducedby Doppler techniques and alternative optical guidance systems. Whenconsidering very low altitude operations, the pilot must balance the benefitsagainst mission objectives and the greater effectiveness of small arms,anti-aircraft artillery (AAA), and very short range SAMs. Within theiroperating envelopes most missiles can be expected to be more maneuverableat low altitude because of better aerodynamic control. Low-leveloperations may also limit the usefulness of the fighter's own offensiveweapons system.Figure 1-10. Effects of Altitude on Missile Range