A 21" torpedo powered by a two-cylinder double-acting reciprocating steam engine and fired from submarines. The engine design bears a marked similarity to the British Whitehead torpedoes which were sold to Japan in 1923. Three modifications of this tor-pedo are believed to exist; however, only one, designated by the Japanese Type 89, Modification 1, has been recovered. The other two, Type 89, and Type 89, Modification 2, have been reported from intelligence sources. This torpedo leaves a visible wake when fired.

The physical characteristics of the torpedo are as follow:

Length Overall – Type 89 - 23'8".

Type 89, Modification 1 - 23'6".

Length of Warhead – 3'8".

Length of Airflask – Type 89 - 10'5".

Type 89, Modification 1 - 13'5".

Length of Afterbody – Type 89 - 9'4" (Including Tail).

Type 89, Modification 1 - 9'4" (Including Tail).

Diameter – 21".

Total Weight – 3660 lbs.

Charge – 660 lbs. Type 94, 97 or Shimose explosive.

Tail Fins – 4.

Range/Speed – 6000 yards at 45 knots.

6550 yards at 43 knots.

10900 yards at 35 knots.

Depth Setting – 6'6 to 52'8.

Warhead – Type 89, Modification 1 - Type 89, Model 2.

Type 89, and Type 89 Modification 2 - Unknown.

Exploder – Type 89 and Type 89 Modification 2 - Bent-lever, nose, impact.

Type 89, Modification 1 - Type 90, bail, impact-inertia, fitted on top centerline of warhead.

Operation

As the Type 89, Modification 1, torpedo travels through the water, pressure depres-ses the bail on the exploder, freeing an inertia trigger and rotating an impeller. The ro-tation of the impeller arms the exploder, and impact of the torpedo with the target dis-places the inertia trigger. This frees a firing pin, which is driven downward under spring pressure onto the detonator, firing the charge.

The operation of the Type 89 and Type 89, Modification 2 torpedoes is similar to the 6th Year Model. As the torpedo travels through the water, an impeller on the nose of the exploder rotates, arming the exploder. Impact with the target shears two pins in the ex-ploder and drives the firing pin onto the detonator, firing the charge. Three bent-levers are attached to the exploder to insure operation in case the torpedo should strike the target at an oblique angle, rather than "head-on".

Safety Precautions

Should this torpedo be found on the beach or in shallow water, it must be considered dangerous. Movement of the bail on the Type 89, Modification 1, on bent levers on the Type 89, and Type 89, Modification 2, may fire the charge. Movement of the torpedo it-self may cause the engine to turn over a few revolutions, driving the torpedo forward, thus actuating the exploder and firing the charge.

Figure 32 – Submarine launched Type 89, Modification 1.