Figure 2.1, is a schematic of the aircraft showing instrumentation lo-

cation; Table 2.3 provides additional details. The bending gages measured
total bending moment and were similar to those used on the wing of the
B~36 aircraft. The oscil@ograph was installed in the aft portion of the
cabin and operated remotely by the co-pilot. A view of the installation
is shown in Fig. 2.15.

n.&

Pig, 2.15
203.7

Oscillograph Installation, B-47B Aircraft

Calibration
Because of the difficulty involved in predicting the precise re»

sponse of a particular part of a complicated structure for a given load

condition, and because of the individuality of each recording channel,
it is generally necessary to calibrate puilt-up strain gage instrumentation experimentally, by applying known incremental values of the related
function and correlating gage output with the applied loads, rather than
uy theoretical calculation. The above experimental procedure was followed for the calibration of all bending, shear, and torsion gages installed
on both aircraft with the exception of the additional instrumentation
installed on the B-26D empennage for UFSHOT~KNOTHOLE. The additional
gages installed on the empennage were calibrated by a system known us the
"point load" system. With this system a given response function is determined by properly combining the outputs of several bridgzs instead of
using the output of a single bridge as in the standard procedure. As
éxplained in the NaCA Report ThZ993, the coint load system is capable of

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