The last aerial torpedo attack in history

I was researching air-dropped torpedoes for an upcoming Weekend Wings article, and discovered that the last recorded use of aerial torpedoes was in 1951, during the Korean War. It was a unique operation in many ways, including the fact that the torpedoes were not aimed at a ship, but at a dam, and were dropped in fresh water, not into the sea!

Intrigued, I did some more research, and found an article in the May-June 2001 issue of Naval Aviation News magazine about 'The Dambusters At Hwachon'. (The link is to an Adobe Acrobat document in .PDF format). Here's an extract.

Located almost 50 miles northeast of Seoul, the 250-foot-high [Hwachon] dam impounded the waters of the Pukhan River, which were high due to the spring thaw.

The Hwachon Dam today

The enemy held two aces. If they blew the dam’s sluice gates, the released waters would flood the valley and stop further UN advances. If they held back the water by closing the gates, the river would be lowered to fordable depths and enable communist infiltration across the river against the exposed allied flanks. Either way, it had to go.

The attempts to blow up this dam rank as some of the most determined of the war. The Air Force was the first to try, using Boeing B-29s to bomb the dam, but they barely dented the 2½-foot-thick gates. Unfortunately, the bombing spooked the enemy, who promptly blew most of the vital Pukhan bridges and opened some of the gates, flooding the lower river. Racing against time, the Army sent in Rangers and mechanized cavalry on 11 April, but they were heavily outnumbered and forced back by fierce resistance. The final straw was when a larger ground attack actually took the dam later in the month, only to be driven out by a ferocious counterattack before they could destroy the sluice gates. The end result was that the dam had become a symbol to the communists of their continued defiance of the West.

. . .

At 1440 on 30 April 1951, Commander Task Force 77 Rear Admiral Ralph A. Ofstie received an urgent message from the Eighth Army. The Chinese had just resumed their “spring offensive,” and the hard-pressed troops on the ground desperately needed help. If two or more of the floodgates could be knocked out, it might prevent the enemy from releasing all of the impounded water simultaneously to inundate the valley and bring operations to a standstill.

. . .

Reflecting the seriousness of the crisis, at 1600 [USS] Princeton turned into the wind and launched the first strike. [Commander Richard C.] Merrick commanded the strike force, comprising six VA-195 ADs under squadron CO Lieutenant Commander Harold Gustav Carlson and escorted by LCdr. E. A. Parker’s flight of five Corsairs from VF-193. Each AD carried two 2,000-pound bombs and multiple 11.75" Tiny Tim rockets intended for the sluice gates, while the Corsairs carried 100- and 500-pound bombs for flak suppression.

. . .

Unfortunately, the strike was in vain. None of the bombs hit the vital gates and the one hit succeeded only in shaking loose a little of the dam’s surface, while the rockets simply skittered off the behemoth. The only bright spot in the day’s tally was that not a single plane was lost in what should have been a suicide mission, although several sported enough holes to startle the crews upon their return.

Regardless, [USS Princeton's commanding officer, Captain William O.] Gallery was still determined to answer the call. During the debriefing, they discussed every option, but no viable solution presented itself until Gallery boldly suggested torpedoes. His premise was that the torpedoes would provide both the accuracy and the punch to tackle the dam, and prior to sailing from the Puget Sound Navy Yard, Bremerton, Wash., Princeton had actually loaded some MK 13 torpedoes left over from WW II.

Mark 13 torpedo, showing plywood screens over the nose (to protect the fuse) and
the tail (to protect the propellers). The screens would break off on entry into the water.

. . .

The high hills surrounding the reservoir continued to limit the approach to a two-plane section runin, while the remainder of the group circled overhead. Making the run-in over the heights surrounding the reservoir required a letdown to drop altitude without exceeding torpedo drop speed. In addition, the drop required limited water space to avoid grounding the torpedo, while still allowing sufficient time for the “fish” to arm. And the departure from the target had to be made down a narrow valley lined with antiaircraft guns. To top it all off, with just eight fish available, only a minimum error rate was acceptable.

. . .

... on 1 May 1951 Merrick led his second strike, consisting of eight ADs from VA-195 and three from VC-35 Det 3, backed up by eight Corsairs from VF-192 and four from VF-193. Looking ungainly with their fish slung under their bellies, the Skyraiders had nonetheless been designed with just such a mission in mind, and they performed beautifully. Arriving over the target at 1130, the pilots were amazed to find the valley ominously quiet. Expecting the guns to riddle them at any moment, they pushed themselves over and went in, only then being greeted by the first bursts of flak. Apparently, the enemy did not expect them to return so soon and was caught by surprise. While the Corsairs went after the guns or circled, each pair of ADs flew in at wave-top level, struggling to hold their letdown to drop altitude so that they did not exceed torpedo speed.

Skyraider armed with Mark 13 torpedo

Running the gauntlet took nerves of steel, each pilot dropping his torpedo and then climbing sharply up the great bulk of the dam as it suddenly loomed over him, waiting breathlessly during those agonizing seconds for his lightened AD to respond. During their run Clapp and English discovered the hard way that their torpedoes were faulty. Both men were stunned to watch their fish swerve at the last minute and avoid their targets completely!

One of the faulty torpedoes strikes an abutment at the Hwachon Dam, May 1st, 1951

Fortunately, the other six torpedoes ran true, slipping momentarily beneath the surface, but then regaining their calibration and racing on to slam into the gates. The explosions echoed off the hills and sent great waves roaring across the reservoir. The center gate was ripped apart, the second gate was torn by a 10-foot gash and one of the abutments was damaged. Circling above, the pilots watched in awe as millions of gallons of water poured through the stricken gates in huge churning columns, flooding the valley for miles.




From this single raid, the enemy was denied control of the reservoir’s waters for the rest of the war.

There's more at the link. It's a very interesting article, and highly recommended reading.

Since the Hwachon raid, as far as is known, no aircraft has launched a torpedo in combat. (Exercise firings of anti-submarine torpedoes by maritime patrol aircraft and helicopters have continued, of course, but as far as I'm aware they've never been used in anger.)

Peter