334 P. Mandel 
In addition, the oscillations arising from rapid vertical ascent or descent and the effects of 
compressibility become nonnegligible for deep-diving submarines. It is believed that the 
compromises made in the design of the Aluminaut effect reasonable solutions to each of 
these problems. 
In particular, the use of iron shot as ballast appears to be a satisfactory substitute for 
water ballast and pumps at very deep depths. The possibility still exists, nevertheless, 
that the iron shot may prove to be redundant for normal ascents and it may prove feasible to 
abandon its use. In that event its equivalent weight would be incorporated in solid ballast 
for use in emergency ascents. 
Model tests have reasonably confirmed theoretical predictions of the measures needed 
to avoid large oscillations in vertical ascents. In particular, the tried and true measures of 
avoiding resonance and incorporating damping devices such as bilge keels promise to yield 
satisfactory solutions. It has been demonstrated that in the panic ascents where it would 
be particularly desirable to avoid large amplitudes of roll the tuning factors are in fact far 
removed from resonance. 
The fact that the overall configuration of the Aluminaut is somewhat less compressible 
than sea water yields the desirable characteristic of stability in depth. This is in contrast 
to thin-hull submarines and earlier bathyscaphes that must drop ballast to achieve neutral 
buoyancy at any depth below the surface. 
The use of a vertical propeller augmented by a hydrostatic trimming system as well as 
stern planes is expected to provide satisfactory depth and pitch angle control at all speeds. 
The possibility of using a trail rope for navigating over the bottom remains to be explored. 
Excellent control in the horizontal plane should be achieved by the ability of the main pro- 
pulsion propeller in conjunction with the rudders to swivel through an arc of 120 degrees. 
Model tests indicated that satisfactory towing of the Aluminaut on the surface could 
probably be accomplished either by towing it stern first or by towing it bow first with a 
bridle arrangement attached to the leading edges of the bilge keels. 
Taken as a whole, the Aluminaut promises to open a new era in ocean exploration and 
ocean utilization. While the primary problems associated with its development lie in the 
field of structures, this paper shows that careful consideration has also been given to its 
potential hydrodynamic problems. 
ACKNOWLEDGMENTS 
The author is indebted to the Reynolds Metals Company of Richmond, Virginia, and the 
Southwest Research Institute of San Antonio, Texas, for sponsoring his work in connection 
with the Aluminaut and for giving him permission to use the results contained in this paper. 
In addition, the majority of the figures contained in this paper were prepared at Southwest 
Research Institute. 
In particular, the efforts of Mr. Ernest Brunauer of Southwest Research Institute are 
acknowledged. It was largely he who shouldered the burden of carrying out the vertical 
ascent tests at the Naval Ordnance Laboratory. In this connection the efforts of the staffs 
of the Underwater Weapons Tank Facility, the Office of Naval Research, and the U.S. Naval 
Underwater Photographic Unit are acknowledged. Mr. Ernst Frankel, Research Assistant at 
M.I.T., conducted the towed directional stability tests. 
