ing the test drops. The nose was screwed into 
the midsection using an "O Ring" seal to make the 
connection watertight. 
The midsection or main body of the vehicle 
(Fig. 2) was an extruded aluminum tube 10-3/4 in. 
in diameter, 48 in. long, with 3/8 in. walls. 
The forward two thirds of the midsection made up 
a watertight compartment containing the recorder 
and all the accessory electronics and components 
of the data system. Two flush-mounted hydro- 
phones were located on opposite sides of the mid- 
section at its midpoint. On the rear of the 
bulkhead terminating the watertight section was 
fixed the recovery mechanism and holddown clamps 
for securing the tail section. Four rectangular 
doors or "drag fins" were mounted flush with the 
outside surface in the afterend of the midsec- 
tion. These were opened (to decelerate the mis- 
sile) by the recovery and tail-locking assembly 
to be described. 
The tail section of the missile (Fig. 3) 
was a cast-aluminum ellipsoid of revolution with 
the ratio a/b = 4. It was 10-3/4 in, in diam- 
eter and 21-1/2 in. long. This section was a 
sealed bouyant body which, when released from 
the forward bodies, rose to the surface trailing 
a nylon recovery line secured to the midsection. 
The tail was clamped tightly in place on the 
afterend of the midsection by means of four tog- 
gles which were locked and released by action of 
the release-recovery mechanism. Figure 2 shows 
the completed missile. Figure 4 shows the the- 
oretically predicted performance characteristics 
of the missile. 
Model studies indicated that the vehicle as 
designed, with a fineness ratio of 7.15 and with 
its mass distribution, would be stable through 
its maximum test velocity. 
The data-recording system and accessory 
components were mounted on a shock- and vibra- 
tion-isolated assembly in the midsection. The 
equipment was integrated into a rigid frame 
which in turn was slid into tracks on a struc- 
ture secured to the watertight after bulkhead by 
Barrymount shock mounts. When the missile was 
in the vertical or drop attitude, the equipment 
was suspended on the Barrymounts and was held 
rigidly in the tracked structure by four wing 
nuts on threaded steel rods. The suspended 
structure was isolated from the shell of the 
missile by suitable rubber pads. The equipment 
rack was easily removable for access to the re- 
ecorder and electronics for calibration and 
changing the tape supply prior to test drops. 
Figure 5 is a view of the electronics rack par- 
tially inserted into itstracked supporting frame 
in the missile. 
PRINCIPLES OF OPERATION 
Data Recording System 
The recorder was a special modification of 
the Stancil-Hoffman standard Model M8 Minitape 
Recorder. This recorder used 1/4 in. tape and 
operated at 15 in./sec. The two record-track 
widths were 0.100 in., separated by 0.062 in. 
The recording heads were shielded to reduce 
crosstalk. The recorder motor was driven at 
3600 rpm; speed control was obtained by using 
a centrifugal governor which varied the shunt- 
field current to keep the speed constant. A 12- 
volt Sonotone sintered-plate nickel-cadmium bat- 
tery supplied power to both the motor system and 
the amplifier system of the recorder. 
Each of the two channels of the recorder's 
electronic system consisted of a preamplifier, 
Model AC23, and a record amplifier, Model AR23. 
A jack was provided by which the output of a 
single full-track playback head could be mon- 
itored. This output provided a signal to an ex- 
ternal playback amplifier during the checkout 
and calibration procedure described below. 
The two transistorized AC24 amplifiers had 
gains of approximately 85 db and input impedances 
designed for 1000 ohms. Each had a push-pull 
stage, using four RCA 2N105 transistors, trans- 
former coupled to a Texas Instrument 2N185 tran- 
sistor. The automatic gain control employed in 
the AC23'!s of the original M8 model was discon- 
nected for preliminary tests. 
The two Model AR24 recording amplifiers fed 
audio signals mixed with a 60-ke bias from the 
AC23's to the recording heads. The input to the 
AR25 was approximately O dbm at less than 1000 
ohms impedance. The output impedance of the 
amplifier fed a recording head of approximately 
3.5 mh, The 60-ke bias appearing across the 
head was 7.5 volts. 
Wow and flutter for the recorder was found 
to be 1% rms, using the standard test. ‘The 
signal-to-noise ratio, measured at 400 cps, was 
determined to be 31 db. The signal level for 
this test was chosen to be the 3% distortion 
point (including nonlinear distortion, hum, tape 
noise). The cross-talk ratio between the re- 
cord tracks was measured to be 55 db. 
Channel 1 of the recorder was used to re- 
