The total in excess of 100 percent proved that many torpedoes were subject to more than one of the defects, just as the bulk of the problems were still due to the effects of poor air stabilization on water behavior.

Better performance at reduced aircraft speeds was small comfort since aviators could not be held down by paper restrictions that imposed serious and dangerous handicaps in combat.

Tank tests using scale models revealed that the "low and slow" approach that had been presumed necessary for a successful drop was actually counterproductive: striking the water at a flat angle frequently caused the after body of the torpedo to "slap", damaging the mechanism.

Experiment soon revealed that optimum water entry angles were approximately 22-32 degrees relative to the plane of the surface: the torpedo might plunge as deep as 50 feet (15 m) but it would return to its set depth and bearing if the mechanism was undamaged.

This enabled the US Navy to develop a series of attack profiles that varied the combination of speed and altitude to produce the ideal 22-32 degree water entry angle.

Finally, there was the added benefit of increased range, as the torpedo traveled a significant distance in the air before entering the water (up to 1,000 yards (910 m) when released at 800 feet (240 m) and 300 mph (480 km/h)).

Combined with radar that delivered the exact range to the target, the results proved to be remarkable:[11] New planes outdated [the] Torpedo Mark 13, but drag rings and stabilizers renewed its usefulness.

Early experiments with parachutes attached to aircraft torpedoes had demonstrated that a drag had a beneficial effect on the airflight characteristics of the weapon.

Oscillations were reduced and the ring effected a 40 percent deceleration in air speed, then acted as a shock absorber when the torpedo struck water.

Better water entry, a byproduct of air stabilization, reduced damage so substantially that pilots were able to increase the heights and speeds at which torpedoes were released.

Even psychologically, the appendages contributed to success, since the external design of the torpedo equipped with a pickle barrel and ring tail and the improved appearance of its underwater travel caught the fancy of the airmen.

To speed the availability of the modified torpedo the Bureau built tail assemblies with the shroud ring attached, then sent them to the fleet as substitutes for the equipment on hand.

The racks took advantage of the Mark 13's air-drop capability by simply allowing the torpedoes to roll over the side, eliminating the risks of a "hot run" within the tube and the flare of burning grease that sometimes gave away the PT boat's position upon firing.

[5] The Mark 13's shorter range and slower speed were considered acceptable tradeoffs for boats that usually operated at night and relied on stealth to reach firing position.