Dutch ordered Douglas DB-7C aircraft as Torpedo Bombers

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Fatboy Coxy

Airman 1st Class
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Aug 24, 2019
Hi all, I understand the Dutch East Indies ordered 48 Douglas DB-7C aircraft to be used as Torpedo Bombers. Events, however, moved faster than they could be produced and delivered to the Dutch, excepting half a dozen, of which only one was assembled, before the Dutch East Indies fell to the Japanese. Many of the remaining aircraft were given to the RAAF, equipping 22 Sqn from April 1942, who used it in a bomb role.

Was there a problem using the DB-7C in the torpedo role, or was the RAAF short of enough torpedo's, or does it take a lot longer to train a torpedo squadron as opposed to a normal bomber squadron?
 
Don't know where you got the story from but it has been muddled in the telling.

The Dutch ordered 32 DB-7B and 48 DB-7C. It was 6 of the former that fell into Japanese hands. 4 of the remaining DB-7B went back to the US and the rest of the DB-7B (22) went to the RAAF. The 48 DB-7C on order were completed as DB-7B and shipped to USSR under lend lease. You will find the story here.

There was not a problem with the A-20 as a torpedo bomber. The USSR used plenty in that role.

And yes dropping torpedoes is more difficult. If the torpedo is dropped outwith its proper parameters it could
1. Break up on entry to the water
2. Dive to the bottom
3. Porpoise and head off in the wrong direction
4. In less sophisticated systems the pilot/bomb aimer has to mentally calculate how far ahead of the target ship to aim and in doing so judge its speed and angle. In more sophisticated systems, as employed on British Beaufighter and Barracuda aircraft there was a "computer" to help. In those the pilot pointed the aircraft at the target ship but still had to make inputs to the system. That needed judgement.

In the FAA it was felt regular practice was necessary so a synthetic trainer was created to assist.

Edit You might enjoy this about Soviet use of the A-20. Scroll down for Soviet Navy use as a torpedo bomber.
 
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Hi EwanS, thank you for such a helpful reply

My info was drawn from the book, The Allied Defence of the Malay Barrier, 1941-1942, by Tom Womack, which I think is a pretty good book on the defence of the Dutch East Indies.

The link to the Soviet use of the Douglas Boston was most interesting, I didn't know the Soviets even used torpedo bombers!.

Regarding the training of aircrew for making torpedo attacks, though it might take longer to train than level bombing, I can't imagine it takes any longer than skip bombing, which requires low altitude flying, and a vital judgement of bomb release. The reason I mention this is because there was an outbreak of skip bombing in the South West Pacific in 1942, quite successful, but I ask the question why?. Was it because aerial launched torpedoes were in such short supply, or some other reason?
 
Regarding the training of aircrew for making torpedo attacks, though it might take longer to train than level bombing, I can't imagine it takes any longer than skip bombing, which requires low altitude flying, and a vital judgement of bomb release. The reason I mention this is because there was an outbreak of skip bombing in the South West Pacific in 1942, quite successful, but I ask the question why?. Was it because aerial launched torpedoes were in such short supply, or some other reason?
Nobody had much success trying to bomb ships from a decent altitude. Virtually everyone, British, Americans, Italians, Germans, Japanese, all tried it and all failed, so creating the need to go in low.

What everyone calls "skip bombing" needs clarification. There was genuine "skip bombing" where the bombs are deliberately pitched short of the target ship with the intention of "skipping" them off the water and into the ship. Problem is that bombs had a habit of bouncing right over the target! And there is "masthead bombing" (or slightly higher) where the intention is to place the bombs directly into the ship (i.e. no skip on the water first). Both methods were practiced in WW2 particularly in the Med and the Pacific. But I do question exactly how often it was true "skip bombing" that was used. In the Pacific by 1944 / 1945 all the photographic evidence points to it being the latter method that was being used by both the USN and USAAF units like the Air Apaches, the 345th BG. Fw 200 Condors were bombing from masthead height.

There were times when torpedo aircraft as well as torpedoes were in short supply. In the SWPA & Solomos in late 1942 / early 1943 it was only USN Avengers and B-26A from the 22nd BG that had torpedo capabilities. But the ground clearance for a B-26A carrying a torpedo was minimal (4"!). Awkward when operating from rough strips. And then there is the question about the unreliabilty of US Mark 13 torpedoes in this period. And let's not forget the few RAAF Beauforts that began to appear from Sept 1942 starting with 100 squadron.

In Europe the RAF moved from trying to bomb ships from masthead heights or torpedo them, either singly or in groups, to the Strike Wing concept from mid-1943. Then the object was for Beaufighters to target the escort with cannon & later rockets while the Torbeaus went in under that cover to sink the merchantmen. For more look at the operations of the North Coates wing initially and then in 1944/45 that Wing plus the Banff and Dallachy Wings operating off the Norwegian coast with Beaufighters and Mosquitos.
 
Regarding the training of aircrew for making torpedo attacks, though it might take longer to train than level bombing, I can't imagine it takes any longer than skip bombing, which requires low altitude flying, and a vital judgement of bomb release. The reason I mention this is because there was an outbreak of skip bombing in the South West Pacific in 1942, quite successful, but I ask the question why?. Was it because aerial launched torpedoes were in such short supply, or some other reason?
Without further research it is hard to say what the problems may have been.
Access to torpedoes is certainly a good possibility. Granted this was 3 years after the start of the was in Europe but some accounts say that the RAF only had 50 torpedoes for their torpedo bombers in England in 1939. That does not count RN stocks or stocks at overseas bases. However much like the lack of resources sent to Singapore in 1940/41 it is hard to see the Australians building up much of stockpile in 1940-41.
There was also changes in how torpedoes were aimed and dropped from 1939 to 1942 which may have complicated training.
The low level bomb technique does require some training/experience but is much less complicated than using a torpedo.
The plane does NOT have to held absolutely level front to back(or darn close to it).
The plane does NOT have to held absolutely level side to side (or darn close to it).
The Plane can be aimed directly at the ship and the plane can be flying faster than a torpedo bomber can drop it's torpedo.
Time from point of release to point of impact is just a few seconds.

For the torpedo, if the torpedo doesn't enter the water at the correct angle the torpedo can break up or become damaged, (Nose and/or control fins/rudders and prop damaged)
If dropped with too great a side angle the gyro/s may topple and not give an accurate course.
Speed goes back to point one, enters the water at the wrong angle or enters with too much force.
Once the torpedo enters the water it slows way down and now you have the race to the impact point between the torpedo and the ship.
Torpedoing an 8kt ship may be fairly easy, torpedoing a 32kt destroyer is a lot harder as the destroyer can mover 4 times of far (and is actually moving at speed unknown to the aircraft) after the torpedo enters the water.
Most aircraft used a torpedo sight of some sort. Either a means of aiming off the bow with a correction for the estimated speed of the ship or a way of aiming at the ship with the estimated speed/distance being fed into the torpedo so that the torpedo steers the correct (?) course to the target after being dropped.
There was lot more to using torpedoes than flying into a convoy and dropping the torpedoes somewhere into a cluster of ships :)

Now in the years after 1942 both the US and British modified their torpedoes' with nose cones/drums and tailfins/stabilizers to allow the torpedoes to be dropped from higher altitudes and higher speeds and have the torpedoes still function after entering the water. During some years the posed publicity pictures of torpedoes being readied for loading onto aircraft did not show the nose cones/drums and the tail devices as they were secret.

hope this helps.
 
Nobody had much success trying to bomb ships from a decent altitude. Virtually everyone, British, Americans, Italians, Germans, Japanese, all tried it and all failed, so creating the need to go in low.

What everyone calls "skip bombing" needs clarification. There was genuine "skip bombing" where the bombs are deliberately pitched short of the target ship with the intention of "skipping" them off the water and into the ship. Problem is that bombs had a habit of bouncing right over the target! And there is "masthead bombing" (or slightly higher) where the intention is to place the bombs directly into the ship (i.e. no skip on the water first). Both methods were practiced in WW2 particularly in the Med and the Pacific. But I do question exactly how often it was true "skip bombing" that was used. In the Pacific by 1944 / 1945 all the photographic evidence points to it being the latter method that was being used by both the USN and USAAF units like the Air Apaches, the 345th BG. Fw 200 Condors were bombing from masthead height.

There were times when torpedo aircraft as well as torpedoes were in short supply. In the SWPA & Solomos in late 1942 / early 1943 it was only USN Avengers and B-26A from the 22nd BG that had torpedo capabilities. But the ground clearance for a B-26A carrying a torpedo was minimal (4"!). Awkward when operating from rough strips. And then there is the question about the unreliabilty of US Mark 13 torpedoes in this period. And let's not forget the few RAAF Beauforts that began to appear from Sept 1942 starting with 100 squadron.

In Europe the RAF moved from trying to bomb ships from masthead heights or torpedo them, either singly or in groups, to the Strike Wing concept from mid-1943. Then the object was for Beaufighters to target the escort with cannon & later rockets while the Torbeaus went in under that cover to sink the merchantmen. For more look at the operations of the North Coates wing initially and then in 1944/45 that Wing plus the Banff and Dallachy Wings operating off the Norwegian coast with Beaufighters and Mosquitos.
I have mentioned on another thread that my father in law, crew chief (top gunner) on B-17s, told of the development of skip bombing. Since he has passed away I can't ask for more details or names, however he describes those who practiced skip bombing had two horizontal white lines painted on pilot's wind shield, one for different weight bombs. When at the proper airspeed, and the correct white line met the ship's waterline, the bomb was released. Several of the B-17 crews used the approach. My father in law went to Australia with the 19thBG.
 
Nobody had much success trying to bomb ships from a decent altitude. Virtually everyone, British, Americans, Italians, Germans, Japanese, all tried it and all failed, so creating the need to go in low.

What everyone calls "skip bombing" needs clarification. There was genuine "skip bombing" where the bombs are deliberately pitched short of the target ship with the intention of "skipping" them off the water and into the ship. Problem is that bombs had a habit of bouncing right over the target! And there is "masthead bombing" (or slightly higher) where the intention is to place the bombs directly into the ship (i.e. no skip on the water first). Both methods were practiced in WW2 particularly in the Med and the Pacific. But I do question exactly how often it was true "skip bombing" that was used. In the Pacific by 1944 / 1945 all the photographic evidence points to it being the latter method that was being used by both the USN and USAAF units like the Air Apaches, the 345th BG. Fw 200 Condors were bombing from masthead height.

There were times when torpedo aircraft as well as torpedoes were in short supply. In the SWPA & Solomos in late 1942 / early 1943 it was only USN Avengers and B-26A from the 22nd BG that had torpedo capabilities. But the ground clearance for a B-26A carrying a torpedo was minimal (4"!). Awkward when operating from rough strips. And then there is the question about the unreliabilty of US Mark 13 torpedoes in this period. And let's not forget the few RAAF Beauforts that began to appear from Sept 1942 starting with 100 squadron.

In Europe the RAF moved from trying to bomb ships from masthead heights or torpedo them, either singly or in groups, to the Strike Wing concept from mid-1943. Then the object was for Beaufighters to target the escort with cannon & later rockets while the Torbeaus went in under that cover to sink the merchantmen. For more look at the operations of the North Coates wing initially and then in 1944/45 that Wing plus the Banff and Dallachy Wings operating off the Norwegian coast with Beaufighters and Mosquitos.
Minor correction on USAAF use of torpedoes. The 22nd BG was equipped with B-26s and later a few B-26Bs. Though equipped to carry torpedoes, and though some training was conducted in Australia, and a little in the US before deployment, the only use of torpedoes was at Midway, when a pair of 408th BS B-26s and a pair of 69th BS B-26Bs attacked the Japanese fleet. The 69th and 70th BS, originally part of the 38th BG and later incorporated into the 42nd BG, trained with torpedoes, but did not use them in combat (aside from the previous use at Midway.) the B-26 equipped 77th and 73rd BS in Alaska were armed with torpedoes for the defense of Dutch Harbor in June 1942, and for a pair of attacks against shipping at Kiska in October that year, but were unsuccessful. Afterward all missions were low level bombing.
 
Having a little dig around to see what torpedoes the Dutch intended to use on their Boston/DB-7's, and I found this lovely web site.


scroll down to Mark 13, and you'll see these were the US mark 13 Aerial Torpedo. I'm not aware of any shortage of these, so presume the Australians of RAAF 22 Sqn, could have used them but didn't, which suggests it's more about training, or preferred tactical use of bombs due to plane or theatre.
 
The one issue with air-dropped torpedoes by twin-engined aircraft in the early part of the war, was that the torpedoes could only be dropped at a certain height and speed, in order for them to function properly.

This in turn, saw the aircraft approaching it's target in a straight, slow flight path. And that meant they were fat, juicy targets for AA defences as well as any defending fighers in the area.
 
Having a little dig around to see what torpedoes the Dutch intended to use on their Boston/DB-7's, and I found this lovely web site.


scroll down to Mark 13, and you'll see these were the US mark 13 Aerial Torpedo. I'm not aware of any shortage of these, so presume the Australians of RAAF 22 Sqn, could have used them but didn't, which suggests it's more about training, or preferred tactical use of bombs due to plane or theatre.
But the DB-7B Boston III and the succeeding A-20C, A & G models were never fitted out for torpedo carrying operationally anywhere other than Russia. It was the unbuilt DB-7C version that the Dutch intended to use as a torpedo bomber, and those were to be fitted with special racks for the purpose. The DB-7B etc came to be used by the RAAF in 1942, not by choice, but because it was immediately to hand in a period of crisis.

22 squadron RAAF was initially used for anti submarine patrols in Australian waters before deploying to New Guinea in Sept 1942. There they flew bombing and strafing missions against targets on land and mostly inshore waters in support of the army until converting to the Beaufighter in late 1944.

By the time these DB-7B aircraft were arriving in Australia in March 1942 the Australian Beaufort torpedo bomber production line was already up and running. The Beaufort was the RAAF torpedo bomber of choice. Deliveries began in August 1941 to 100 squadron RAF in Australia. On 25th Feb 1942 it was transferred to the RAAF along with all its aircraft and all subsequent production intended for the RAF.

100 squadron RAAF flew its first operational sortie in May 1942, initially anti submarine patrols in Australian waters and then anti shipping work out of bases in New Guinea where it used both bomb and torpedo (the US Mk 13 which it found grossly unreliable). It's first torpedo sortie was Sept 1942. There are various claims about its first torpedo successes being in the Nov 1942 to Jan 1943 period on IJN destroyers and cruisers but sources seem to conflict.

7 & 8 squadrons RAAF also used the Beaufort in the torpedo role in 1943, the latter using British Mk.XII torpedoes at one point. But other RAAF Beaufort squadrons were either engaged in maritime patrol work or bombing in support of the army so did not train in torpedo dropping.

After Rabaul was neutralised in early 1944 there was a lack of shipping targets worthy of a torpedo so the RAAF stopped using them. By then most Japanese shipping traffic in the New Guinea area is described as "barges" which had a shallow drought and were moving in shallow coastal waters. Neither feature favoured using the torpedo. So the bomb became the best weapon for the task. And a greater role emerged in support of the army ashore. And by the time that the US was finally sorting out its torpedo problems in 1944 it had ceased to be an effective weapon due to the changing nature of the targets.
 
scroll down to Mark 13, and you'll see these were the US mark 13 Aerial Torpedo. I'm not aware of any shortage of these, so presume the Australians of RAAF 22 Sqn, could have used them but didn't, which suggests it's more about training, or preferred tactical use of bombs due to plane or theatre.

unbuilt DB-7C version that the Dutch intended to use as a torpedo bomber,

The DB-7B etc came to be used by the RAAF in 1942, not by choice, but because it was immediately to hand in a period of crisis.

The Dutch/Australian DB-7B/Cs have a somewhat convoluted history. The DB-7Bs were never fitted for torpedoes and that is what the Australians got.

The DB-7Cs were from a later production batch and not the tail end of the DB-7B order. The DB-7Cs were built but were assigned to the AAF as they were still in the US at the time the Dutch East Indies fell, in fact were in varies stages of completion at this time. Some of the DB-7Cs were assigned to training units in the US but most wound up going to Russia. Apparently they were completed with non standard equipment of unspecified type which made the AAF not want to give them US serial numbers?

The A-20Gs (at least some of them) were "equipped" to take the MK XIII torpedo. Aside from the DB-7Cs they were the first A-20s to be so equipped. Use was more problematic in that in order to house the torpedo the bomb bay doors had to be removed and the torpedo mounted on a slant so that the nose protruded down past the bottom of the fuselage.

Torpedoes themselves were never plentiful. The Big American carriers often only carried 36 or so at a time. In other words the Lexington, Saratoga, Essex and Enterprise could only launch 36 planes armed with torpedoes without being resupplied. Sending torpedoes off to land bases after the Dutch were over run was probably not going to happen.
Torpedoes are also not "rounds of ammunition". Torpedoes need periodic maintenance from specialists.
 
Torpedoes themselves were never plentiful. The Big American carriers often only carried 36 or so at a time. In other words the Lexington, Saratoga, Essex and Enterprise could only launch 36 planes armed with torpedoes without being resupplied. Sending torpedoes off to land bases after the Dutch were over run was probably not going to happen.

My understanding is that in that timeframe the USN was woefully deficient in torpedo stocks, and the Connecticut factory was running at a snail's pace.
 
Torpedoes themselves were never plentiful. The Big American carriers often only carried 36 or so at a time. In other words the Lexington, Saratoga, Essex and Enterprise could only launch 36 planes armed with torpedoes without being resupplied. Sending torpedoes off to land bases after the Dutch were over run was probably not going to happen.
Torpedoes are also not "rounds of ammunition". Torpedoes need periodic maintenance from specialists.
Inter war the USN had an on-off relationship with the airborne torpedo and the torpedo bomber. By 1932 only Lexington still had a torpedo squadron. The USS Ranger CV-4 was completed in June 1934 without any provision for carrrying torpedo bombers or their weapons as the dive bomber became the favoured carrier weapon (the capability was re-instated in 1941 but she only carried 6-9 torpedo bombers in WW2). The construction of Yorktown and Lexington (service entry 1937/38) saw the torpedo bomber gain favour again with the introduction of the TBD Devastator (130 built) to equip the 4 torpedo squadrons on Lexington, Saratoga, Yorktown and Enterprise. Each squadron had a complement of 18 aircraft. In battle the carriers were not expected to survive very long.

USN airborne torpedo development was also a stop start process in this period. It was not until 1938 that the first specifically designed airborne torpedo entered service, the Mk 13 Mod 0. Production of this was low because, unlike bombs, they were recoverable after training exercises. So only 156 were built. That was enough to provide each operational aircraft on each of the 4 carriers with two torpedoes plus 12 for trials etc. Incidentally Brtish carriers were generally designed to carry 1.5-2 torpedoes for each torpedo bomber in this period.

What do you mean by plentiful?

Production had begun again by mid-1940 with the MK 13 Mod 1, to cope with the planned expansion of the torpedo bomber force as new carriers came into service starting with the USS Wasp CV-7 in April 1940 (she only carried 9 or 10 TB during her career) and Hornet CV-8 in Oct 1941. But with additional carriers not expected until early 1944 (the planned completion date of CV-9 Essex before the massive acceleration of the build programme after Pearl Harbor) there was no rush to produce vast numbers of torpedoes. While torpedoes were therefore perhaps not "plentiful" in the early war period that changed as time went on. Production figures for the Mk 13 by year were as follows:-

1940 (last 6 months) - 149
1941 - 521
1942 - 1,800
1943 - 6,762
1944 - 6,463
1945 (to August) - 449

By 1942 of course the USAAF wanted them to equip various aircraft and in due course they came to be used by PT boats as well. This from the NavWeaps site:-



"From "US Naval Weapons" by Norman Friedman:

"A review of war experience showed a total of 1,287 attacks [this count only includes those launched by carrier-borne aircraft, other US Navy aircraft launched another 150 torpedoes - TD], of which 40 percent (514) resulted in hits, including 50 percent hits on battleships and carriers (322 attacks, including Midway), 31 percent on destroyers (179 attacks), and 41 percent (out of 445 attacks) on merchant ships."

This hit percentage is much too high, but illustrates the over claiming that was typical of all nation's pilots during the war.
Although not mentioned by Dr. Friedman, at least eight Japanese cruisers were struck by aircraft torpedoes during the war."


Edit - by the end of the war torpedo bomber squadrons on the CV had been reduced to 15 aircraft each and there were plans to reduce their numbers further and to eventually replace them altogether with more SB2C dive bombers (although a requalification process was carried out in 1945 on the latter to allow it to carry torpedoes if required)
 
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Skip bombing, General Kenny states the idea began as dropping a bomb with a 5 second delay fuse, in level flight at about 50 feet "a couple of hundred feet away" from a ship, the idea seems to have been multiple skips. The B-26 trials came up with 100 feet altitude, 400 yards range. Then came the Port Moresby wreck trials, 200 mph, 200 feet, 300 yards range, on 23 October 1942 it was tried by 6 B-17 at night at Rabaul. But the B-17 was too big and vulnerable that low, at least by day, so the idea was solid nose B-25.

The RAAF came up with an experimental computer and sight, based on the G.M.2 reflector sight. Doing trials that showed from 100 feet altitude 60% of bombs were within a 20 yard diameter group, at 50 feet that rose to 75%

Torpedo bomber, 100 squadron RAF was in Singapore in December 1941, beginning to receive Australian produced Beauforts, remnants of the unit made it to Australia in February 1942, becoming 100 squadron RAAF.

The RAAF attempts to use torpedo bombing did not work, there was no pre war expertise to seed the building of a training and maintenance system. The Base Torpedo Unit formed at RAF Nowra in September 1942, 1 Mobile Torpedo Maintenance Unit formed in November 1942, taking command of Mobile Torpedo sections at the various airfields, number 2 Mobile Torpedo Maintenance Unit formed in February 1943. Supply problems meant using US torpedoes which did not fit the Beaufort properly, increasing drag. There are no confirmed torpedo hits.

Report of 16 August 1944. Trials of air launched Australian built mark XV torpedo satisfactory. Trails of mark XIII Mod. 2A with "Drag" ring successfully dropped from 275 feet, 160 knots. Trials with modified igniter to improve sealing and prevent cold runs. Report of 1 November 1944 Mark XIII Mod 4 successful drops from 1,500 feet at 300 knots. (RAAF using mark XII Mod 2A). Mod 4 adds shroud ring and strengthened after body. 2 November 1944 confirmation successful torpedo drops from 2,000 feet, 300 knots.

The RAAF torpedo capacity was handed over to British Pacific Fleet in 1945
 
What everyone calls "skip bombing" needs clarification. There was genuine "skip bombing" where the bombs are deliberately pitched short of the target ship with the intention of "skipping" them off the water and into the ship. Problem is that bombs had a habit of bouncing right over the target!
And the French were crazy enough to do skip bombing on land ...
 

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