revolution of the record disk. The base line was retraced every 20
sec making a maximum of 4 1/2 revolutions if the full recording time
B.2.3
a
Rod
ul
Initiation Systems
These gages could be initiated either thermally or by means of
‘The standard method
was the thermal initiation system. A spring loaded plunger was held
in place by two brass shims soldered together with an alloy having a
melting point of approximately 175° F. The thermal energy of the detonation melted the alloy breaking the link and releasing the plunger.
The, plunger actuated a switch which completed the motor drive circuit
jand.started
the recording mechanism.
3
wh
The phototube initiating system was easily assembled. Requiring
the’ removal of the plunger and the addition of a latching relay inside
net
LN
The turntable speed at the stylus point was 0.5 in./sec.
a photo electric cell (see Figures C.3 and C.4).
NP
the gage case.
The phototube (Type 917) actuated a strobtron (Type
631-P1) Which in turn caused the latching relay to close completing
the motor |drive circuit. The photo initiation was used very little to
due tolitg susceptibility to moisture, causing premature initiation.
B.2.4 Field Mptitications
a
The okGdssivedetrimental effects of acceleration on the gage
records as obtained(ai)Sh
Shots 1 and 2, indicatethat, if usable
pressure-time reas 4 “va going to be obtained immediate modifications
would be requir'i,,
|}
-f the machine work on gage components,
though counireleliksedheptable, was not of the precision required to
insure proper operation
r conditions of high acceleration.
The following mo
for Shot 3, and all the
cations were made on a number of gages used
arm was shortened to dee
s used in Shots 4, 5 and 6; (1) The stylus
Se the moment arm of the stylus point.
(2) A numberof adjustable felft]and rubber tipped friction brakes were
machihed and assembled beneath
the backlash of the turntable
the turntable.
By adjusting this brake
Was dampened. (3) Additional set screws
were provided to hold the turrthble more solidly on its shaft. (4) The
turntable and motor coupling shaft yushings were replaced with new
bushings.
The new bushings were madhjined more accurately and length-
ened to provide more bearing surfac¢ ;
prevent wobble. (5) The turn~
table coupling shafts were replaced iby precisely machined shafts having
a good sliding fit in coupling shaft wuishitg.
These modifications apparently
acceleration effects.
It is felt, howcvey,}
pb completely alleviated the
that many more modifica-
tions should be made on these geges prior ib use in any future operaetePan ea
puns
B.3
pn
my
tion.
DRUM TYPE PRESSURE-TIME GAGE
i
t
a
—
eetey
j
aprot,
Roatanrssae
on
apm
ah
cetsats
“Wearssetpeaetl
was used.
B.3.1
General
Pon
|
The drum type pressure-time gage was designed
cf
J
a self-re-
cording scratch gage incorporating the feature of a r@c
g blank
whose base line was not retraced after the first revolution.
The recording blank was an aluminized glass cylinder with a di-
58