A weapon with two journeys
An aerial torpedo travelled through air before becoming an underwater weapon. An awkward entry could damage it or prevent a steady run, even when the aircraft crew had brought it within reach of the target.
The Bureau of Ordnance’s official history describes early Mark 13 problems with course, depth and propellers damaged by the shock of entry. It identifies control of the airborne fall and entry angle as central difficulties. This is a retrospective institutional account, published after the war, rather than a record of every torpedo dropped at Midway. M59
The cost of getting close
At Midway the weapon belonged to an attack system that included aircraft, fighter cover, coordination and the target’s defences. Hornet’s report records the loss of all fifteen aircraft in its torpedo squadron’s morning attack. That loss cannot be reduced to a torpedo malfunction percentage: aircraft could be shot down before release, and a released weapon could miss without failing mechanically. The report’s claimed hits are not treated here as confirmed results. M58
The ordnance history connects criticism after Midway with the hazards of the slow, low approach demanded by contemporary torpedo attacks. Better weapon performance alone would not remove the need to get aircraft through the defence. M59
A frequently misplaced statistic
The official history describes a test of 105 torpedoes in mid-1943, dropped above 150 knots, in which only 31 per cent gave satisfactory runs. That is evidence of serious continuing trouble under those test conditions. It is not a measured failure rate for the weapons dropped at Midway a year earlier. The listed fault categories also overlap, so adding them produces a misleading total. M59
Improvements came later
By 1944, a wooden drag ring helped stabilise the airborne fall and reduce entry shock; a shroud ring helped steady the underwater run. The history dates distribution of the combined improvements to autumn 1944. Their later success must not be projected backwards onto June 1942. M59
A later attack, a different constraint
Bennington’s VT-82 report records Mark 13s aboard TBM-3 Avengers on 7 April 1945, with a twelve-foot running-depth setting and reported releases at 800 feet. The crews chose escorts rather than Yamato because they considered that setting unsuitable for an attack beneath the battleship’s belt, and most aircraft lacked the radioman who could make the adjustment. These are the report’s stated tactical reasons; they do not establish an exact modification fit or the success of every weapon. YT-Y18
Compare the TBM-3 Avenger, the Japanese Type 91 and The Morning Strikes. Exact Midway malfunction counts remain unresolved; the technical history explains a weakness without supplying a result for every weapon.