A 17".7 torpedo powered by a two cylinder double-acting reciprocating steam engine and designed for use by midget submarines. The use of oxygen instead of compressed air give the Type 97 a high speed and leaves only a very slightly visible wake.

The physical characteristics of the torpedo are as follows:

Length Overall – 18'5".

Length of Warhead – 5'11".

Length of Airflask – 7'11".

Length of Afterbody – 4'7" (Including Tail).

Diameter – 17".7.

Total Weight – 2205 lbs.

Charge – 790 lbs. Type 97 explosive.

Tail Fins – 4, top vertical one smaller than other three.

Range/Speed – 3500 yards at 46 knots.

Depth Setting – 6'.6 to 50'.

Warhead – Type 97.

Exploder – Type 90, bail, impact-inertia in pocket on top centerline of warhead.

Operation

As the torpedo travels through the water, pressure depresses the bail on the explo-der, unlocking an inertia trigger, and rotates the impeller. This arms the torpedo, and im-pact with the target displaces the inertia trigger, and frees the firing pin, which, driven under spring pressure, strikes the detonator and fires the charge.

Safety Precautions

This torpedo must be considered dangerous if it is found in shallow water or on the beach. Movement of the exploder bail might fire the charge. Likewise, movement of the torpedo might allow the engine to turn over a few revolutions, driving the torpedo for-ward on the beach. This might actuate the exploder, firing the explosive.

Figure 37 – Type 97 torpedo used in midget submarines, powered by oxygen.
It travels with only a slightly visible wake.