Fighter Combat

APPENDIX 405In theory the energy transfers beginning at points A, C, and E in thisexample are instantaneous. In practice, however, the aircraft attitudechanges necessary to make the transition from climbs to dives, and viceversa, are made slowly and result in a rounding-off of the corners in theclimb profile, as shown by the broken lines in these areas. Also because ofthe finite times involved in such energy transfers, climbs of fairly shortduration can sometimes be made more quickly by following "nonoptimum"paths, which avoid these time-consuming techniques.Because of the difficulty of following optimum climb profiles precisely,approximations are usually made. A typical rule of thumb for the fighter inthis example might be: climb at .92 M to 25 KFT, then accelerate to andclimb at 600 KIAS. Optimum climb profiles for subsonic jet fightersusually begin with a slowly decreasing indicated airspeed until the jetreaches approximately critical Mach, and thereafter a constant Mach numberis maintained.The advantage of using this best energy-rate climb profile as opposed toopting for the nominal best climb-rate path (approximated by the "subsonicpath") is quite apparent in the ultimate energy levels attainable.Along the subsonic path this fighter can reach about 51 KFT, and fromthere it could zoom to about 66 KFT (E s = 66 KFT), while the supersonicpath provides energy levels (and therefore zoom capabilities) in excess of100 KFT.Acceleration PerformanceThe important thing in aeroplanes is that they shall be speedy.Baron Manfred von RichthofenAircraft accelerate most quickly by maximizing thrust while minimizingdrag. Equation 4 shows that this condition also tends to maximize P s/so an H-M diagram can give a good indication of the relative accelerationcapabilities of a fighter throughout its flight envelope. At any given altitudea fighter tends to accelerate fastest at a speed just slightly below thatat which PS peaks (subsonic peak for supersonic fighters).Techniques to optimize acceleration include using the highest possibleforward thrust and reducing weight and drag as much as practicable.Jettisoning external fuel tanks and nonessential ordnance is useful, sincethis action reduces both weight and drag.One of the most effective methods for improving the acceleration performanceof fighters is known as "unloading." This involves pushingforward on the pitch controls to reduce load factor, lift, and induced drag.For most fighters induced drag is minimized at a zero-G condition, whichmay be recognized either by cockpit G-meter readings or by "seat-of-thepants"indications such as the pilot's feet floating off the rudder pedals,loss by the pilot of any sensation of pressure against the seat, or loosearticles and dirt floating around in the cockpit. This last indicator can behazardous, resulting in jammed controls or dirt in the pilot's eyes, andshould be avoided by securing loose articles and maintaining a cleancockpit.