3 feet to insure that the vehicle will remain 
afloat even if any of the various flood and 
vent valves leak. Also, the flotation bag will 
be painted a highly visible color and perhaps 
have a radar reflective surface. 
Fig. 2 shows in tabular form the physical 
and performance characteristics of the first 
Porpoise vehicle. It is emphasized that the 
performance data is for a vehicle equipped 
with a 3,000 psi gas storage cylinder. With 
a solid or liquid fueled hot gas generator, 
which is proposed as the system for the opera- 
tional vehicle, the performance will be greatly 
increased. For example, with a hydrazine or 
ethylene oxide gas generator system, this 12 
foot long vehicle would have a range of about 
26 nautical miles and a depth capability of 
at least 1,000 feet. Also, use of a hot gas 
generator in a 12 foot vehicle will allow 
increasing the instrumentation payload to 
about 2.5 cubic feet. 
PROGRAM PLAN 
Under the present contract with the Office 
of Naval Research, Chance Vought will design 
and fabricate one twelve foot long vehicle 
configured with a compressed gas system. The 
vehicle will be delivered to the Navy in early 
1962. Proposals for follow on work including 
additional vehicles, a hot gas generator de- 
velopment program, and a field test program 
are currently being evaluated by the Office 
of Naval Research. The test program proposed 
consists primarily of feasibility demonstra- 
tions in the Dabob Bay test facility of the 
U. S. Naval Torpedo Station, Keyport, 
Washington. The instrumented test range of 
the Dabob Bay facility is considered to be 
ideal for the initiai demonstration since 
tracking accuracy of about +1 foot is ob- 
tainable. Water depth is about 600 feet and 
total available range at the facility is 
several miles. Therefore, for demonstration 
of the full capabilities of the hot gas 
generator configured Porpoise, it will be 
necessary to move to the open ocean. 
FUTURE CAPABILITIES 
Fig. 3 shows the range performance which 
is expected from Porpoise vehicles of various 
sizes with two types of liquid monopropellant 
fueled gas generator systems. Vehicle length 
is plotted against range since range remains 
practically constant for a given amount of 
fuel regardless of the maximum depth of opera- 
tion. For example, a 20 foot vehicle con- 
figured with an ethylene oxide gas generator 
system would have a range of about 56 nautical 
307 
miles with a 10 cubic foot payload. Operating 
this vehicle at a maximum depth of 1,000 feet, 
the distance traveled per cycle is about 1.33 
nautical miles, requiring about 42 cycles for 
the mission. If the maximum depth is changed 
from 1,000 feet to 2,000 feet, then the dis- 
tance traveled per cycle is about 2.67 nautical 
miles requiring only 21 cycles for a 56 nautical 
mile range. However, since the pressure against 
which the gas generator must expel the ballast 
is doubled, then the fuel requirement is ap- 
proximately doubled for each cycle. Therefore, 
total range will not change. Depth of operation 
is limited by the amount of fuel required for 
one cycle to that depth and by the pressure at 
which the decomposition of the ethylene oxide 
or hydrazine can be made to take place. 
The curves for various payload volumes as a 
percentage of total vehicle displacement simply 
indicate the effect of reducing fuel volume 
and increasing instrumentation payload volume. 
The use of hydrazine fuel in the vehicle 
will result in a 10% or 15% greater performance 
than that obtainable with the ethylene oxide 
fuel. However, hydrazine costs about $3.00 
per pound whereas ethylene oxide costs only 
about $0.25 per pound. The difference in cost 
may well justify selection of the ethylene 
oxide for most applications. 
Similar performance curves are shown in 
Fig. 4 for a solid propellant fueled gas genera- 
tor and a water reactant fueled gas generator. 
An obvious disadvantage of the solid propellant 
system is that a separate propellant cartridge 
or charge must be provided for each cycle de- 
sired,and each cartridge must be sized to 
expel the water ballast at a specific maximum 
operational depth. If it is desired to go to 
a greater depth, two or more charges must be 
fired simultaneously. Therefore, maximum 
range can be obtained only at the cartridge 
design depth and even multiples of that depth. 
The water reactant curve shown indicates 
that lithium hydride as a fuel could provide 
more than twice the performance of the solid 
or liquid fuels. However, lithium hydride as 
a fuel for Porpoise may be further in the 
future than the other fuels because of avail- 
ability, cost, and the difficulties that may 
be encountered in controlling the lithium 
hydride gas generation reaction. 
Fig. 5 illustrates some profile variations 
attainable with future Porpoise vehicles. 
Since the vehicle is a glider, the limits on 
flight path angle and velocity are relatively 
small. By simply providing a wing incidence 
adjustment, it will be possible to obtain a 
velocity of about 15 knots ata 20° glide 
angle. This, of course, reduces the horizontal 
distance traveled per cycle for the same 
