eee:

zontal tail loads made by two different and completely independent
methods,

Frior to IVY, the cesirn limit upload on the horizontal tail of
the 636 aircraft was ruolished as 33,.00 lb. Further analysis and re-

calenlation by Sorsolidated Vultee Aircraft Corporation (CVAC) after
IVY produced a revised desiom limit load of 63,000 lb. This higher fig-

ure was later confirmed by static tests conducted by CVAC under contract

to WADC. The tests were not -:ompleted until aftet Shot 9; therefore,
the 36 aircrart was positioned on the lower allowable tail load for
this shot, as well as the two IVY snots. In this report, however, all

coi varisons of mecsured loads with desiim limit load are made with res-

pect to the hisher fisure of 63,000 lt.

On this busis the peak measured

loud «as only 45 per cent of desi.n limit loud; however, if calculated
on the same tusis used to position the aircraft, the peak measured load
would have approacned more closely the desivn limit.
In 41] exrosures tne aircraft were positioned with the tail toward
the e«plosion; therefore, symmetrical ioadins: on the wing and horizontal

tail was ex;ected.
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-3

hye’,

rendinr meacurements on the rirkt and left wing at station 390

were ecudvailent for Mike and Kine Shots cut differed greatly in Shot 9.

Althoush no direct evidence hus veen found that would invalidate either
of the ~eacurerents, Sor reasons given oelow it is velieved the lower

value, which wis thet meacured on the left wing during Shot 9, is incorrect, und aujmmetrical loadin, 13 not indicated,
To Jetermine whether or not mecsured values were in approximate
ayreement relutive to each other, the maximum positive bending moments
meaourped at eacn instrumented station for each shot, except for the sta-—
tion farthest outooard, were plotted as a function of the distance from
the aircraft center line.

The resuiting curves drawn Zor each shot are

shosn in Fig, 4.1. The r«lationship of tendi:- moment versus span cal
culated for the condition of uniform load snows it is ceasonable to exreet a plot of peak values to ;roduce a curve of the reneral shape shown,
1.4.,

tigher loads at the inbourd stations, decreasing with increasing

span.
.. dynamic analysis would be required ta determine the exact curve
at any given time. The aveve method of cumrurison provides a good check
on the validity of the test, duta, The peu: cending moments from station
106° have not veen plotted because the influence of the higher vibration

modes caused the peak value to ve reached at a much earlier time than

for the instrumented stations inboard of «tation 1062,

The response

curves of the suspect measurements made at station 2990 are practically
identical. except that the left wing meacurement consistently equals one-

half the right wing measurement.

This low reading can easily be explain-

ed as an instrumentation failure; however, «cxeludiniy data reduction er-

rors, it is almost impossiole for an instrumentation failure to cause a
hivh ceading. The peak value of these Shoat 4 measurements have both

been rlotted in Fig, 6.1.

The curves presis..cd were iIrewn c

th? basis

of the composite data, excludins the point: in question, and show that
the nhicsher value is in the revion predicted ty the curve, whereas the

lower value falls consicerably celow the curve.

If the Shot 9 curve

vl

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