6.2 Shaping Constants for Atlas IIAS
6.2.1 Optimum Mode-5 Shaping Constants
~~~~~~~~~~~~~~~~~
available, random-attitude failures were simulated for a no-breakup case and for three
breakup qa's: 20,000 deg-lb/ft2, 10,000 deg-lb/ft2, and 5,000 deg-lb/ft2. For each case,
270,000 trajectories were run, giving a total of 1,080,000. It turned out that the value
chosen for the breakup qa was critical in determining shaping constant A, since the
lower the qa, the less the thrusting time before breakup, and the higher the percentages
of impacts in sectors near the flight line.
For Atlas HAS, the effects of qa on breakup are shown in Figure 6 where, for the
selected qa's, the percentages of random-attitude turns that result in breakup before
280 seconds are plotted against failure time.
. .' ' ' '' ' ' '
100 '
,1- - -1-, l i AtlasillAS l
90 ......... , ... • ......,/--;',, .... \ .... • ...................: ....................f ....................: ................ .
I 1/ i \ \: i , i 2
:: j \ \ i q-alpha in deg-lb/ff ......... , ....,....................: ........... , ....rt· .................:....................: ....................t............... ..
80 I I • \ • • ; •
I 1: : , 1: -+ q-alpha = 5 000
.... 7···/+...................f.............~....~ .........:::..=i~..cfalptta··;··,-0~600..........
- 70 , , , \ I , , ' '0
-~
- 60C:
Q)
~ 50Q) ·1' l:i...............\i,,~--1·q·alp1a=20,r0 •••••••••a..
a. 40::::,
:::,::.
ct1
Q) 30 1cc
'-
i ............1................ ...... __ / __ ~, .. i............ ! ................... !.................20 l : !
. . l 1 !.................1....................1............................................................1....................1.................10
·················r···..···············r····················;···················-r· • •0
0 40 80 120 160 200 240 280
Failure Time (sec)
Figure 6. Atlas IIAS Breakup Percentages for Random-Attitude Turns
For failures between 10 and 30 seconds, most breakups do not occur at failure, but later
in flight after the vehicle has built up significant velocity. For failures between 40 and
105 seconds, more than 80% breakup occurs, even for qa's as high as 20,000 deg-lb/ft2.
9/10/96 37 RTI