we lll el ke we we we i mea? 8 STABILIZER cENDING The time-history curves for bending measurements made at station 62 of the horizontal stabilizer during Mike and Shot’ 9 are shown in superposition in Fig, 6.2 to facilitate comparison of the two responses, To obtain a clearer presentation, the curve for King Shot was omitted; however, since the stabilizer response in King Shot was similar to that of Mike except for amplitude, comparisons of Mike arid Shot 9 will suffice to show veneral response differences. As shown in the figure, both curves show the characteristic double peak followed by a lower peak, Furthermore, the peaks occur at approximateiy the same time in both curves and are displaced from each other at approximately equal inter- vals, suggesting the peaks correspond with the natural frecuency of the stabilizer, Thus, the regularity and sirilarity of response ootained in the three independent tests lends strong support to the conclusion thas the dita represent actual Lending stresses induced. Other than magnitude, the only essential difference between the Shot 9 and Mike responses is the relatively high negative bending moment measured in Shot 9 and undetected in Mike. The return to zero after the rositive pulse was more gradual in Mike and no appreciable negative bending moment was attained. This difference in stabilizer response is ate tricuted rrimarily to the difference in positive phase duration of the shock .ave on Mike and Shot 9. The longer positive phase in Mike Shot causec the upload on the stabilizer to te maintained for a longer times, there. y inhioiting the natural spring-back of the stabilizer. FHecause of this effect, the peak neyutive Lending moment was both delayed and of a low amrlitude. Tne maximum cending moment recorded was during Mike Shot of IVY. west Oo, RM ee Me Re He Oe ee wre 6.3 Le eH eM mee This value represented 45 ner cent of the present design limit load. During UPSHOT-KNGTHULE, only 34 per cent of design limit loud was realized, However, is explained before, these values are based cn the new decivn Limit Load that was verified after the tests. If the old limit load were used, their values would have been much higher. “he bending moments measured on tie horizontal tail of the B~36D aircrac‘t using tne conventionel metnod were in good agreement with the point load method, For Shot 9 the vending moment measured at station 62 on the cisht stabilizer was sli,htly lower than that measured on the left for voth the conventional and point lead method, The shear, measured only by the point load system, 13 aiso lower ot station 62 right than at station 62 left. There sre several possible explanations for this difference in measured lo:ds. The most prvooable explanation is that the test aircraft was not pointed directly away from the explosion, thereby giving a side load on the vertical fin thit was transmitted to the horizontal stabilizer. A load on the icft side of the vertical tail would tend to increase the vending morent on the left horizontal tail and decrease the tending moment on the right horizontal tail. Since the loads measured by two completely independent methods agree; i.e., both methods give higher values on the left side, it is believed tnat the measurements are correct and that there is a definite reason for the difference. ovale ree eee . hea Po