PERIOD- SECONDS 
Deep-Diving Submarine Hydrodynamics 327 
NATURAL PERIODS OF ROLL 
OSCILLATION FOR DIFFERENT 
BUOYANCY CONDITIONS 
Oo I 2 3 4 5 6 
ASCENT VELOCITY, fps 
Fig. 12. Full-scale computed excitation and oscillation periods 
6. The two panic ascent conditions, 8 and 9, are so far removed from resonance that 
strong oscillations are extremely unlikely. 
EFFECTS OF COMPRESSIBILITY 
Pressure hulls of either shallow- or deep-diving submarines deform elastically under 
the external pressure of submergence. The associated loss in volume is usually small and 
