PORPOISE — OCEANOGRAPHIC RESEARCH VEHICLE 
by W. L. CANNON, Project Engineer 
Chance Vought Corporation 
Dallas, Texas 
ABSTRACT 
A description of an oceanographic research 
vehicle called Porpoise is presented. The 
vehicle, under development by Chance Vought 
Corporation under contract with the Office of 
Naval Research, is essentially an underwater 
glider that utilizes buoyancy control as a 
means of propulsion. The vehicle described is 
le feet in length with a maximum range of about 
26 nautical miles and a depth capability of 
1,000 feet. Performance increases are predicted 
for various sizes of vehicles using several 
types of gas generators. 
INTRODUCTION 
Porpoise is an underwater giider that 
utilizes buoyancy control as the motivating 
force to obtain forward velocity. The vehicle 
is being developed as an oceanographic research 
vehicle by Chance Vought Corvoration, under a4 
license agreement with Oceanic Systems 
Corporation. At the present time Chance Vought 
has a contract with the Office of Naval Research 
to design and fabricate one vehicle for demon- 
stration of the feasibility of the concept for 
oceanography. 
CONCEPT AND OPERATION 
Fig. 1 shows a sketch of the Porpoise 
vehicle and a portion of a typical mission 
profile. The mission would begin with launch 
of the Porpoise vehicle from an oceanographic 
vessel. The launch operation would consist of 
Simply lowering the vehicle into the water 
from the deck of the ship and releasing the 
vehicle on the desired heading. The vehicle 
will take on water through the flood valve 
while the entrapped air escapes through the 
vent valves located along the upper surface 
of the vehicle. Since the flooding begins 
forward of the center of gravity, the Porpoise 
vehicle will pitch over and, as it becomes 
negatively buoyant, begin its descent. Ata 
preset depth below the ocean surface, perhaps 
60 feet, a hydrostatic pressure sensing con- 
trol mechanism will close the flood valve and 
the vent valves. At this point, the vehicle 
305 
will be full of water and will descend at an 
angle of approximately 14 degrees with a ve- 
locity of about 10.5 knots. Then, at a pre- 
set depth, the compressed gas control valve 
will be opened, allowing the air or nitrogen 
from the storage tank to enter the ballast 
compartment. The water is then expelled from 
the ballast compartment through the ballast 
outlet valve which is a spring loaded valve. 
Since the water is expelled from the forward 
portion of the vehicle first, a moment is 
obtained which causes the vehicle to begin a 
pitch-up maneuver. When the water is completely 
expelled from the vehicle, and the gas flow 
terminates, the pressure across the hull 
equalizes and the spring loaded ballast out- 
let valve closes. The vehicle now is posi- 
tively buoyant and is rising at an angle of 
about 14 degrees and a velocity of approxi- 
mately 10.5 knots. As the vehicle approaches 
the surface, the depth sensing mechanism opens 
the flood valve and the vent valves to again 
flood the vehicle. Then, of course, the 
vehicle becomes negatively buoyant, pitches 
over, and begins another cycle. 
The wing configuration is designed to pro- 
vide high roll Sets and the wings have 
equal angular travel (11°) both up and down 
since the wings will be up when the vehicle 
is gliding downward and down when the vehicle 
is gliding upward. 
The instrumentation payload is located in 
the nose of the vehicle. The payload case 
will be separated from the ballast compartment 
by a double watertight bulkhead to facilitate 
instrumentation payload installation and re- 
moval. This allows all instrumentation check- 
out, calibration, and maintenance to be done 
in the laboratory, then installation of the 
payload case on the vehicle just before the 
vehicle is launched. By providing a number of 
payload cases with different instrumentation 
configurations, a good flexibility of mission 
types would be available with a minimum of 
change to the vehicle or any payload case. 
The flotation and marker system will be 
actuated on the final cycle of the mission as 
the vehicle reaches the surface. The flota- 
tion bag is inflated to a diameter of about 
