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Skip Bombing

Discussion in 'Air War in the Pacific' started by Devilsadvocate, May 12, 2008.

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  1. Devilsadvocate

    Devilsadvocate Ace

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    The aerial tactic of skip bombing, as practiced by the Fifth Air Force under General George Kenny, proved deadly to Japanese shipping in the Southwest Pacific, most notably in the Battle of The Bismarck Sea in March, 1943. In that battle between ships on one side and aircraft on the other, US and Australian bombers used high, medium, and low level bombing, plus "skip bombing" to devastate a Japanese reinforcement convoy bound for New Guinea. Twelve Japanese freighters and troop transports were virtually annihilated along with half of their eight escorting destroyers, The Japanese losing an estimated 12,700 officers and men, while the Allies lost 13 airmen. But where and when did this tactic originate?

    The ragged remnants of the Allied FEAF which had been successively run out of the Philippines and the NEI formed the core of the Fifth Air Force in early 1942. It's aircraft were heavy bombers, mostly B-17's, and a handful of other types, including light attack planes and medium bombers. It's doctrine was entirely standard USAAF strategic bombardment doctrine first formulated by Billy Mitchell. The USAAF had never contemplated fighting a campaign in the Pacific and had devoted scant attention to designing either planes or tactics to suit the requirements of the Pacific war as it unfolded. Strategic bombardment doctrine was focused on an air war in Europe and envisioned massed fleets of bombers attacking city-sized targets with hundreds or even thousands of tons of bombs over distances measured in hundreds of miles.

    The reality in the Pacific was much different. Because of the "Europe First" policy, air commanders were restricted to strikes using, at most, a couple dozen bombers flying over oceanic distances measured in thousands of miles, and attacking targets the size of ships or airfields. There simply were no "vital centers" of industrial production; shipping and air bases, plus a few concentrations of ground troops or supply depots were all that presented themselves, and these targets called for quite different tactics and equipment. It was quickly learned that heavy bombers, attacking from 20,000 to 30,000 feet were completely ineffective against these smaller, and, often moving, targets.

    By the time, General Kenny assumed command in July, 1942, this fact was obvious. Kenny realized this and, being a proponent of attack aviation (what we would call tactical aviation today) as opposed to strategic bombardment, his first innovation was to lower the bombing altitude to levels where there was a chance of hitting these small targets. Against small moving ships, this meant very low altitudes indeed, sometimes described as "mast-height".

    General Kenny had experimented with skipping bombs into targets in the late 1920's, first trying it against land targets, but finding that bombs skipped off of the ground developed very unpredictable trajectories and missed as often as they hit. But when he tried the same tactic against water-borne targets, he found that it was possible to skip bombs off the surface of the water in a very predictable way. But these were simply experiments and since the great majority of USAAF officers in those days were strategic bombardment oriented, they excited no great attention and had no influence in shaping USAAF doctrine or tactics.

    It was actually the British, early in September, 1939, who first tried low-level and skip bombing tactics against actual naval targets with mixed success. But they continued with these types of attacks and developed a workable method of consistently hitting moving ships. In August, 1941, General Hap Arnold was in England as an observer, and apparently ignorant of Kenny's earlier experiments, learned of these British tactics and, on his return to the US, ordered a doctrine for the employment of skip bombing to be developed for the USAAF. Before these experiments could culminate in a tactical doctrine, however, The Pacific war was precipitated by Pearl Harbor. Interestingly enough, it appears that RAAF pilots used either mast-height, or skip bombing tactics, it's not clear which, with some success on the very first day of the war in Malaya, attacking Japanese troop transports attempting to land troops in northern Malaya at Kota Baharu. Either the Australian pilots had somehow heard of the earlier British successes, or were simply trying out their own innovation because it seemed to give the best prospect of success.

    Because skip bombing required a relatively large plane to make a long, low level, head on approach to the target, it was relatively easy for AA gunners on the ship to hit the bomber. Thus, heavily armed vessels presented dangerous targets. At first, General Kenny used B-17's to make skip bombing attacks, but because the average B-17 lacked enough forward firing guns to keep ship-borne AA gunners from firing back, the attacks were performed at night or during early dawn hours when it was difficult for the defenders to pick out an approaching plane against the dark background. But after Pappy Gunn, one of Kenny's best pilots and all around "mad scientist", had modified A-20 attack planes and B-25 medium bombers to carry from four to twelve forward firing .50 caliber machine guns, daylight attacks using these "gun-ships" became the norm. Usually two plane elements were used, one plane distracting and/or strafing the ship's gunners while the other set up for it's bombing attack.

    It was found that a plane strafing with up to twelve .50 caliber MG's could virtually clear the decks of even the most heavily armed warship long enough to allow the attacking plane to make it's bomb run completely unhindered by return fire. The accuracy of these low level bombing attacks was simply phenomenal compared to medium and high altitude bombing. For example, at the Battle of the Bismarck Sea, the high altitude bombers, in 17 attacks comprising 105 sorties dropped 387 bombs, achieving 29 hits representing a very respectable (for high altitude bombers) 7.5% hit ratio. But the 14 mast-height missions, comprising 56 sorties dropped 137 bombs and achieved 48 hits for a spectacular 35% hit ratio.

    As mentioned earlier, the Fifth Air Force was not the first to practice skip bombing, the British, Australians, and even USN squadrons used skip bombing to good effect whenever it seemed appropriate. But the Fifth AF developed the tactic to greater heights than anybody else, and with specially modified planes, bombs, and doctrine, turned it into an art form. The Fifth AF innovated it's way into the history books by crushing the Japanese effort to supply their bases and garrisons in and around New Guinea and the Solomons. Skip bombing was but one, albeit an important one, of the tactics they used to accomplish this. Fortunately for the US, the Japanese were never able to imitate this very effective tactic due to the fragility of their lightly built attack aircraft which simply could not carry the heavy forward firepower required to make the tactic feasible.

    The link at the bottom of this page is to a complete, 164 page book in .PDF format which details skip bombing and other innovations practiced by the Fifth AF. It's well worth downloading and reading to get a detailed account of these innovations and a history of the air war in the Southwest Pacific.

    http://aupress.maxwell.af.mil/Books/Rodman/rodman.pdf
     
  2. Za Rodinu

    Za Rodinu Aquila non capit muscas

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    Skip bombing looks like a cheap and effective way to save torpedos :)
     
  3. Devilsadvocate

    Devilsadvocate Ace

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    Yes, it would seem so. And it was much more effective than high level bombing against shipping targets, its a wonder it wasn't used more widely in WW II. But it did require quite a bit more training and practice than high level bombing to be really effective. And it must have taken real guts for a pilot to fly into the teeth of AA fire from heavily armed warships even with the massive MG batteries mounted on the bombers which were used for this purpose. We can be thankful that the Japanese didn't have any planes heavily built enough to be used for this sort of attack, it was devastating to naval targets.
     
  4. Za Rodinu

    Za Rodinu Aquila non capit muscas

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    I agree, Devils, it certainly needed a lot more guts and expertise than flying straight & level at 20,000 ft. And from that height aany bomber would be bound to miss any ship, even if it were the USS Carl Vinson dead in the water!
     
  5. Tomcat

    Tomcat The One From Down Under

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    I read a book about mosquito pilots skip bombing to destroy German ships in Norweigian Fjords, they would have to fly down the length of the fjord and dodge the enemy AA fire then skip the bombs and fly up and out, without getting hit.
     
  6. TA152

    TA152 Ace

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    It would be tricky to set the bomb fuses correctly in order not to get the bomb to go off when it hits the water and to go off when it hits a ship.

    In the Falkland's war bombs skipped over the water, hit British ships and passed through them and only then did they explode.
     
  7. Devilsadvocate

    Devilsadvocate Ace

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    I wasn't aware of this, but my hats off to any pilot who would attempt such a thing in a Mosquito without the massive forward firing MG batteries that were developed by the Fifth Air Force in the SWPA. They must have had ice water in their veins! The book that I read about the Fifth Air Force did mention that some squadrons took only volunteers on skip bombing missions and did not require anyone to fly the mission if he did not want to.



    It was tricky. The Fifth Air Force usually used bombs with 4-7 second delay fuses. The fuse was initiated by impacting the water and then skipped into the ship's side. Sometimes the bomb didn't penetrate due to hitting obliquely, but it would sink into the water under the ship and explode, which was as damaging as a direct hit, the ship would frequently break in half. A big problem, especially if the water was not relatively calm was that the bomb could easily be thrown back up at the attacking plane; that must have been a nail-biting experience to see you own bomb, with an active fuse, coming back up to meet you.

    In all that I have read about WW II skip-bombing attacks, I have never heard of a bomb going completely through a ship, although It seems plausible that it might happen. It may be that the pilots aimed their attacks at portion of the ship where some solid object, like engines, or loaded cargo holds would impede the bomb, causing it to detonate inside the ship. The book about the Fifth Air Force emphasized that the pilots always dropped two or three bombs in quick succession so that if one missed or failed to reach the target (or went right through it!), there would be at least one or two other bombs that hit the deck or registered a damaging near miss.
     

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