B-26 Marauder weapons thread

Great photo Greg
Possibly close to freezing and 15cm/6in of water on the ground
FUN

The airfield at Adak was built by closing off the mouth of a lagoon and filling it with crushed rock and sand, then paving it with Marston Matting. The river that flowed into the lagoon was rerouted, but the hasty construction left the field subject to frequent flooding. Watch "Report from the Aleutians" to get a good idea what it was like.
View: https://www.youtube.com/watch?v=0-Y2hZVCThA

WOW
Liquid cooling like I have never seen before

B-26s and torpedoes.
Although much was made of the B-26's capability as a torpedo plane, it proved a complete failure in USAAF operations.
Testing in the States was conducted in late 1941, but the Mark XIII torpedo's drop parameters were simply too limited for the B-26.
The original Mk XIII had to be dropped from under 50 ft. at a speed not exceeding 110 knots (126 MPH). This was below the stall speed of a torpedo laden B-26, which became unstable at speeds below 175 MPH. The modified Mark XIII, which featured a special "aero-wing" tail stabilizer, designed to break away upon impact with the water, permitted the torpedo to be dropped at faster speeds from higher altitudes, up to 200 mph at 200 ft. This in theory gave the Marauder a chance to successfully launch the torpedo.
Unfortunately, the operational debuts in defense of Midway and Dutch Harbor on 4 June 1942 were marred by inadequately trained crews lacking proper torpedo sights. None of the crews had ever dropped a torpedo before. At Midway two B-26s from the 408th Bomb Squadron, 22nd Bomb Group joined with two newly arrived B-26Bs of the 69th Bomb Squadron, late of the 38th Bomb Group, were sent out against the Kido Butai. Weathering swarms of Zeroes and walls of AA fire from the Japanese ships, three Marauders survived to drop their fish, but scored no hits. Only two Marauders made it back to Midway, but both were so shot up they never flew again.
In the Aleutians, B-26s of the 73rd and 77th Bomb Squadrons, 28th Composite Group, fanned out from Umnak and Cold Harbor in search of the Japanese Northern Force, lurking in the fog and squalls of the Northern Pacific. One B-26, piloted by Cpt. George W. Thornbrough, located the Japanese fleet but was unable to achieve an effective launch angle. Giving up, Cpt Thornbrough attempted to drop the torpedo on the deck of the Ryujo, like a bomb, but missed. He then returned to Cold Harbor, loaded up with bombs and went out again, but failed to find the fleet. He and his crew were lost when the weather deteriorated and he could not locate his base. Another flight located the fleet and launched their torpedoes at a cruiser in the screen, but failed to score.
Although training with torpedoes was conducted by all Pacific based B-26 units throughout 1942, the only other operational use recorded were two missions launched by the 73rd Bomb Squadron, 28th Composite Group, against shipping in Gertrude Cove, Kiska, on 14 November 1942. The Borneo Maru, previously damaged by bombs had been run aground in the cove. Three B-26s attacked in the morning, but one torpedo cartwheeled upon impact with the water, another missed the ship, exploding against the rocky shore (but failing to sink the island) and the other plunged into the mud of the shallow cove. A later attack by three more Marauders resulted in all torpedoes suffering similar misfortune. After that the Aleutian Marauder units stuck to bombs, experiencing great success against the Japanese destroyers Oboro and Hatsuhara just two days later. Six B-26s loaded with 300 lb bombs were vectored to the ships inbound to Kiska and attacked from masthead height, losing one of their number, but scoring hits on both destroyers. The Oboro was sunk with heavy loss of life and the Hatsuhara was crippled and had to limp back to Japan, where it spent nearly a year under repair.

I just found a pic in Stanaway and Rocker's "Eightballers - a History of the 8th Photographic Reconnaissance Squadron" that shows an early B-26 with package guns ca. October '43. The Eighth used a hand me down B-26 from the 22nd BG as a transport and even flew a recon mission with it before it lost an engine in late '43. All Pacific based B-26s and B-26Bs were retired from the inventory in Jan '44, so it probably never flew again. No tail code visible. Darn. The nose cone was modified to accommodate a forward facing camera. Pretty neat.

Based on combat reports from the Pacific, it was obvious that the B-26 would need some modification before deploying to fight the Nazis.
In July of '42 a modification program was instituted to increase the capabilities of the B-26B. Uprated engines R-2800-41 with provision for sand filters were installed in all B-26Bs destined for North Africa and the UK, unofficially known as B-26B-1, and all guns were upgraded to .50 caliber, one fixed and one flexible in the nose, two in the deck turret, one each in the right, left and ventral waist positions, and two in the tail. Armor was also increased in key locations. These same upgrades were applied to the B-26B-2. B-26B-3 and -4 were given similar treatment, but with R-2800-43 engines.
Perhaps one of the most famous photos of a North African based B-26, showing the three waist guns:

The increased weight of the flexible .50 caliber in the nose required the nose be reinforced with a V shaped brace behind the Plexiglas, as well as reinforcing metal strips on the outside. The position of the gun was lowered to the center of the nose cone, as opposed to the higher position of the original .30 caliber mount. A ring and bead sight was installed on the fuselage in front of the pilot for the fixed gun.

shortrounds6 said "I always thought the the 5800lb load was a pair of 1600lb AP bombs and a torpedo?
Torpedo hanging on the outside really plays havoc with the speed "

I've seen that load quoted before. I can't imagine anyone actually trying to fly that mission. Though apparently someone in the 22nd BG did fly a mission with a torpedo slung under, 3 500lb bombs and a 250 US gallon bomb bay tank in the forward bay. Lucky for him, the reported Japanese carrier never materialized.
Just think: I spot the enemy carrier, drop down to 200' and slow to 200MPH on my approach to the drop point while the CAP and AA has their way with me. Drop the torpedo, open bomb bay, knocking off 25-30MPH for the drag of the open bomb bay doors and skip bomb the carrier, at just about stall speed. Maybe jettison the fuel tank as well over the carrier for good measure. Now I'm clean, so shut the bomb bay and firewall it, pushing the MP to 70" 'til I outrun the Zeros.

Anybody seen the performance chart for a torpedo laden B-26

I always liked the idea of attacking a battleship with that load

Go in and do the torpedo run (and 200mph is much too fast for the MK 13 torpedo in 1942) make the low altitude escape, spend 4-5 minutes climbing to 8,000ft and make a return run with AP bombs which need to dropped from around that height in order to penetrate the deck/s.

200MPH at 200' is the attack envelope prescribed for the torpedo armed Marauder in 1942. (Midway and Aleutians) Probably why they all missed.
The RAF had a bit more luck with their torpedoes, but gave it up after a few missions.

As far as I can tell, no B-26 ever carried anywhere near that load into battle. The 69th and 70th Bomb Squadrons flew with four 250 gallon tanks from Hamilton Field CA to Hawaii, but removed all armor and weapons to make weight.
Typical loads in the Pacific were 3000 lbs for short range missions (PM to Lea or Buna) or 2000 lbs with a 250 gallon bay tank when going to Rabaul.
Mission loads quoted in "Revenge of the Red Raiders".

Greg Boeser said:

200MPH at 200' is the attack envelope prescribed for the torpedo armed Marauder in 1942. (Midway and Aleutians) Probably why they all missed.
The RAF had a bit more luck with their torpedoes, but gave it up after a few missions.

Click to expand...

According to Campbell's "Naval Weapons of WW II" the original drop conditions were 110kts and 50ft. By Feb of 1944 box type detachable wooden tails, drag rings and "pickle barrel" false heads allowed for high speed drops from 1000ft and by the end of the war drops could be made at 410kts from 2400ft.




Perhaps dropping from the higher altitude and higher speed gave the same entry angle into the water??
Too flat an entry and the torpedo could break up. Too steep and torpedo dove too deep and might not run right.

There was an earlier box tail with scalloped sides that was used without the nose gear. Perhaps this allowed the higher speed/altitude?

They actually found that the low and slow torpedo drops hurt the weapon more than ones at higher speed and altitudes. The low and slow drops belly flopped the torp into the water and were more likely to damage it. The higher speed drops with the wooden fins and nose cap enabled the torps to enter the ocean nose first, with the shock of impact distributed along the length of the torp rather than sideways. Even without the extra wooden furniture the torps probably would have worked better if dropped higher and faster.

And on the later PT boats they did away with the torpedo tubes and just dropped air-launched type torps into the water. Saved a lot of weight on the boats and eliminated the misfire problem that had them banging the tube with a hammer.

Here is an Aleutian based B-26 with the torpedo. You can see the stabilizer clearly. This photo is dated May 1942, so just before Midway/Dutch Harbor.

Here you go Greg, short bit about the 77th Bomb Group document using Navy personnel to load torpedo's as they had no experience loading them.

Nice shot of the B-26!

The TBD guys who were at Midway said that they added wooden "fins" to their torpedoes, to try to make them more aerodynamic. But they were still using the low and slow belly flop technique, which was exactly the wrong thing to do with that poorly designed, poorly built, inadequately tested Mk 13 Torpedo

Thornbrough probably had the right idea when he dropped his in a dive, hoping to hit the Ryujo with it like a bomb. Just missed. Think of the damage a one ton object striking a ship at 300 mph would cause! Even if it didn't explode.

Just think if those B-26's had been equipped with 10 or 20 100 lb bombs when they flew across and down those carrier decks!

They had no training on torpedo attacks. And the torps they were using were horrible, the product of decades of work by govt feather merchants who, by working very hard were proud to boat they could hand-build 50 torpedoes a month - that pretty much did not work. The actual wartime requirement was around 1500 a month.

When the submarine USS Nautilus came across the ravaged and abandoned Akagi, dead in the water, they hit it with 4 torpedoes. None exploded. One torpedo's warhead broke off and sank and the remains was used as a flotation device by Japanese crewmen.

It's an interesting question. We know now that skip bombing or masthead bombing was far more effective at destroying shipping than level bombing at altitude, or trying to score a hit with a defective torpedo. The Midway crews had no prior torpedo experience other than a few flights to familiarize them with the flight characteristics of a torpedo laden a/c. The best examples of masthead bombing by Marauders in the Pacific is the 11th AF up in the Aleutians. 73rd Bomb Squadron only came to grips with the enemy a few times, but their best mission was 16 October 1942, when they caught the DDs Oboro and Hatsuhara on a fast resupply run to Kiska. Six Marauders attacking in two flights dropping 300 pounders scored several hits on both ships, sinking Oboro and crippling Hatsuhara, but lost one plane and crew to AA and suffered one KIA on another plane.

I want to learn more about the low level attacks, especially the Battle of the Bismark Sea. After 10 months of unsuccessful high and medium bombing attacks, the USAAF witjh B-25's, along with A-20's and Aussie Beaufighters attacked a IJN convoy coming down the Slot. To the utter astonishment of the IJN the air attacks sank every single transport ship as well as the convoy commander's destroyer. A couple of weeks later a B-17 did a low altitude attack on an IJN cruiser and left it dead in the water. And the IJN knew the jig was up. There is no place they would be safe. Then the USAAF shot down and killed Adm Yamamoto. After Kicking A and taking names in the Solomans the IJN left, its tail between its legs and its head down.

It was not true skip bombing but low altitude bombing. It was taught at my home town, Columbia SC, using nearby Lake Murray as a bombing range. I recently bought a book about the man who thought up that method of attack, entitled, "Indestructible."