Flightdeck Friday: Torpedos and OOB Thinking

Off today to Norfolk to speak at the winging of the next class of replacement NFO’s at the E-2 FRS (VAW-120) – more on that later. -SJS

1 MAY 1951

Today’s subject – the torpedo attack on the floodgates of the Hwachon Dam, is an example of what today is described as thinking out of the box. Things were desperate in the ground following the combined Chinese/North Korean offensive launched in early April. As described in the May 2001 issue of Naval Aviation News:

On 5 April the Chinese and North Koreans launched their fifth offensive aimed at pushing the United Nations (UN) forces back from the 38th parallel. Numbering 70 divisions, the communists were determined to isolate South Korea’s capital of Seoul with a double-flanking movement, and launched four Chinese communist army groups against the 75-mile front between the Hwachon Reservoir and Munsan. Two weeks of seesaw fighting stretched the 1st Marine Division thin. On 22 April when the 7th Marines were dug in around Hwachon and spotted movement on the nearby hills, they knew what was coming. Shortly after dark the stillness exploded as bugles, sirens, whistles, gongs and screams announced a huge Chinese attack. On their left the 6th South Korean Division disintegrated, exposing the Marines’ flank.

Yet as tough as things were on the ground, it would have been worse if the Communists had control of the air:

Chinese General Peng Dehuai bitterly observed that had the communists controlled the skies during these earlier offensives, “the American and British invaders would already have been eliminated in Korea.” The truth was that in their effort to stop communist aggression, U.S. planners were increasingly forced to rely upon the firepower of the air-ground team to offset the enemy’s numbers.

And now, in the Hwachon region, American commanders were pondering some way to leverage their advantage in the air to benefit those on the ground…

With rising casualties, U.S. planners desperately searched for a way to break the deadlock, and looming foremost was the Hwachon Dam. Located almost 50 miles northeast of Seoul, the 250-foot-high dam impounded the waters of the Pukhan River, which were high due to the spring thaw. 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 2fi-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.

Time for something different:

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.

Ofstie gave CDR Merrick (“CAG”) the daunting task. Since the 20-foot-high and 40-foot-wide gates made a vulnerable target for aircraft, the enemy strengthened the dam with rocks. The 4,000-foot ridges surrounding the reservoir limited access to only two aircraft at a time, making their runs against such a tiny target even more difficult.

Reflecting the seriousness of the crisis, at 1600 Princeton turned into the wind and launched the first strike. 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.

Carlson led the first pair in while the others orbited overhead. CVG-19 noted that “the straight-away was very short and speed control was accomplished by extremely precise flying.” Actually, the approach was difficult enough without the added threat of enemy fire, but no sooner did the first pair go in than the valley erupted as the communist batteries opened up with everything they had. Swooping in low, the Corsairs blasted every antiaircraft site they could identify, searching frantically for the telltale puffs that marked the guns, while the Ads flew the gauntlet in rapid succession, straddling the dam and knocking a hole squarely in the middle.

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, 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.

Note that Gallery was CAPT William O. Gallery, CO of USS Princeton. So – while debriefing the crews and examining all possible alternatives, CAPT Gallery recalled a bit of recent history and mindful of the torpedos they’s loaded aboard prior to deployment, offered up the suggestion that they use those to attack the floodgates:

A similar plan had been tried once before, though not with torpedoes. During WW II three great dams provided the primary power for most of Germany’s industrial heartland in the Ruhr region. Realizing their significance, the Germans packed the narrow approach along the valley with antiaircraft guns, making any attempt to knock them out certain to be a nightmare. On the night of 16-17 May 1943, British wing commander Cdr. Guy Gibson valiantly led the 19 Avro B.MK I (Special) Lancasters of No. 617 Squadron in a strike against the Eder and Mohne dams by “bouncing” huge 9,250-pound bombs into them. For this epic raid Gibson received Britain’s highest award, the Victoria Cross.

With this inspiring example, the flight crews worked through the night repairing the aircraft and arming them with eight MK 13s brought up from below decks where they were buried behind the other ordnance. Ensign Robert E. Bennett, one of only three pilots who had practiced antishipping tactics, said, “We trained extensively at coordinated tactics against shipping on a previous cruise, before Korea, and we got good at it.” Still, most of them had never dropped a torpedo, much less tried anything this unorthodox. In fact, Bennett recalled that he had never even seen an aerial torpedo before Hwachon. Thus, they decided to include on the strike three VC-35 pilots who had already practiced torpedo drops, Lieutenants Arthur F. Clapp, Frank Metzner and Addison R. English.

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.

Bennett elaborated, “Too high and the torpedo would enter the water steeply and dive. Too low and the torpedo would skip off the water. There was difficulty also in slowing down to maximum drop speed, and if the ball wasn’t centered, the torpedo wouldn’t run true. The torpedoes were finicky little devils.”

Indeed they were as the first run was to prove. With twelve Corsairs in company as fighter screen/flak surpression, the big, blue Skyraiders commenced their first run:

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.

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!

Still they persisted:

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. The elated pilots returned to Princeton for much needed rest. The squadron historian can perhaps be forgiven if he allowed his pride to get the best of him while listing his squadron’s accomplishments. Near the bottom of a long list of targets hit, ranging from bridges to tanks and barrels of fuel, he added an unusual item: “Flood Gates: 2 Destroyed, 1 Damaged.”