MIL-STD-81OD Downloaded from https://www.everyspec.com 19July 1.983 (1) Wave shape - damped sine wave (2) Wave frequency - determined by structural analysis of specific aircraft and location fundamental.mode. : (3) Burst amplitude - same as above (4) Wave Damping (quality factor) - Q = 20 (5) Axis - vertical, transverse ,,, , .i, (6) Number of bursts - determined by the specific application (for example, 30 bursts, each followed.by a 10.second’ rest period) ,, d. ~. The catapult launch/arrested landing shock e-nyiron”ment differs from other typical shock events in that it is in realitY s transient :. periodic vibration (roughly sinusoidal) at a relatively low fnew=wy deter-.
.; mined by aircraft.mass and landing gear damping characteristics. Typical ~ catapult launch and arrested landing shock time hietories are shown in figure 516.3-6. ., In general, catapult time histories.will,show two &QS’i@k. eventS .:. corresponding to imitial load application and catapult separation from the aircraft, with both transient everta having a dist,inctoscillatory nature ~ (reference f). For,the ,purposesof this-procedure,however,.this time histor?y has been simplified to a constant-amplitude sine burst of 2-second duration of approximately similar characteristics.. ,, ,, ,.
the long periods of application and high frequency of occurrence have the potential to cause significant damage in improperly designed equipment. . While the pulse ampl~tudes associated with this eriviionmentare low, A typic”alaircraft may fly as many as 200 sorties per year.,of which more than two-thirds may involve catapult launches and arrested landings. However, for laboratory test purposes, 30 ?imulated catapult/landing.events in each of two axes (longitudinaland vertical) s,hould provide good confidence that,the majority of significant defects will be identified for remedial action. ,. 5- . .. Vert;cal I 0 ,, .... % -5 -%, 1 I 1 I 1 , , , I , , , , I 1 , , , I , , 1 , 1 I 0.
1.0” 3.0 5..+ Time After Initiating Launch (See) ed Vertical & 3 .,, ., ;. u o 4 ., -3 .:.,.,. 0 0.5 1.0 1.5 Time After Initiating Arrestment (See) .?. FIGURE 516.3-6. l@.cal reqxmssgu.i.p ent to fa@zuLLku@Mund m -~ing os@&at orv nature Oc (Reference f) t@THOD 516.3 19 Juiy 1983 : 516.3-16