Fighter Combat - Tactics and Maneuvering

408 APPENDIX
turn performance (i.e., rate and radius) improves, but total aircraft drag also
increases. Eventually a load factor is reached at which the entire thrust of
the engines is needed just to offset this drag, leaving no excess power for a
simultaneous climb or for acceleration. Equation 4 indicates that when
thrust equals drag, Ps is zero. Figure A-14 shows how the zero-Ps line reacts
by shrinking and deforming under increased G. This process is further
illustrated by Figure A-17.
This figure consists of H-M plots of the same supersonic jet fighter at
load factors of 3 Gs and 5 Gs. The outer curve in each case is the 1-G Ps = 0
line for reference. Within this 1-G envelope are specific-excess-power
values (in ft/sec) for the two sample load factors. Note that the zero-Ps
envelope shrinks considerably in the 3-G plot, and even farther under 5 Gs.
Figure A-17. H-M Diagrams for 3 Gs and 5 Gs