Swordfish vs Devastator

[Schweik]

The same or smaller numbers of Stukas (or SBDs, or Skuas or bomb armed Albacores or Swordfish) were quite likely to have achieved the same results. None of these ships represented difficult or hard to sink targets and the end result is not surprising or exceptional.

Hahahahah yeah, I don't agree. SBD's yes- they too were quite deadly. Skuas? You gotta be kidding. Albacores or Swordfish would have been hard pressed to even reach the target and wold have been decimated by the CAP (before and after the raid)

I think this is the real crux of the debate we have. You (and I know some others here as well) seem to rate a bomber exclusively by bomb load. I think, based on reading the operational histories, many of the other factors like range, accuracy, maneuverability etc. actually mattered more. Particularly range and accuracy, especially when it comes to naval war. Few bombers in the war really had decent bombing accuracy, and the D3A was definitely one of those in that rare category.

 

[RCAFson]

Hahahahah yeah, I don't agree. SBD's yes- they too were quite deadly. Skuas? You gotta be kidding. Albacores or Swordfish would have been hard pressed to even reach the target and wold have been decimated by the CAP (before and after the raid)

I think this is the real crux of the debate we have. You (and I know some others here as well) seem to rate a bomber exclusively by bomb load. I think, based on reading the operational histories, many of the other factors like range, accuracy, maneuverability etc. actually mattered more. Particularly range and accuracy, especially when it comes to naval war. Few bombers in the war really had decent bombing accuracy, and the D3A was definitely one of those in that rare category.

The 16 Skuas that attacked Konigsberg scored 5 x 500lb bomb hits. The Skua was a very competent divebomber but suffered in this role because they were so often used as fighters. Well trained DB crews are going to achieve similar results, regardless of aircraft types, given a large sample size as all except for the Stuka had simple bomb sights. Prewar trials of Swordfish produced these results:

In 1939 Swordfish dropped 366 practise bombs against the target ship Centurion and averaged about a 70 yd error at dive angles from 60-70 degrees (Smith, Dive Bomber), and this would equate to about 33-50% hit rate against a Hermes sized target. Being able to drop multiple bombs per attack sortie should increase the hit rate per sortie.

 

[yulzari]

The last several pages have taught me so much about the Swordfish Vs Devastator. Is it time to mention the P39 yet?

 

[Airframes]

Only if it can drop nutsacks from 1,500 feet, at a dive angle of 60 degrees .......................

 

[Shortround6]

When discussing whether a not a particular aircraft is a ship killer we tend to overlook two things (or more).

1. the plane does not actually sink the ship, that is the bomb or torpedo. The plane just gets the bomb/torpedo to the drop location.

2. skill/determination of the pilots/crew. Best bomb/torpedo in the world doesn't work if dropped from too far away. or too hastily and trajectory does not take it to the target.

Once you know that the bombs/torpedoes were equal and that the skill and/or training of the pilots/crews were somewhat equal then the stability/speed/whatever of the plane can be discussed.

Skua gets a bad rap, In 1939 few other dive bombers carried much more bomb load as far. The first SBD-1 didn't fly until May of 1940, Anybody want to compare the Northrop BT-1 to the Skua??
Skua also had a crap bomb, A semi-armor piercing bomb with about 92lbs of explosive. The RAF and the FAA didn't have a1000lb when the Skua was designed and in fact the British only built 159 of the 1000lb GP in 1940 so the RNs chances of getting ahold of any were effectively zero.
The British 500lb bomb wasn't going to penetrate a battleships deck (or even a good heavy cruiser) and it didn't have enough explosive to really wreck lightly armoured or unarmored ships or battleship topsides. A german 250kg SC bomb held 267-287lbs of HE, depending on exact model and type of explosive. Stuka with a single 250kg SC bomb is delivering almost 3 time the explosive of the bomb the Skua carried. US 500lb GP bomb carried about 250lbs of HE.
Something to consider when evaluating hits.

 

[Schweik]

By 1942, bombs are a lot better all around. The ordinance still makes a lot of difference with torpedoes, but bombs are only so different.

Crew training is certainly a real factor - the IJN in early 1942 was much, much scarier than the IJN in 1944. Same thing for the Luftwaffe whose bombers were not nearly as intimidating as they had once been. But factors like effective range are still hard limits (quite literally) on how effective a bomber can be. Which is where this particular side-debate actually started.

 

[Schweik]

In 1939 Swordfish dropped 366 practise bombs against the target ship Centurion and averaged about a 70 yd error at dive angles from 60-70 degrees (Smith, Dive Bomber), and this would equate to about 33-50% hit rate against a Hermes sized target. Being able to drop multiple bombs per attack sortie should increase the hit rate per sortie.

There were all kinds of wildly optimistic tests done pre-war. Dropping a bomb when there is no flak or light AAA shooting at you is like shooting targets at a range as opposed to in a real firefight. Or punching a heavy bag instead of a jerk in a bar who might punch you back.

Billy Mitchell arranged a series of stunts where B-17s were intercepting and dropping bombs on the decks of ships at sea. The government spent a half billion dollars developing the supposedly miraculous Norden bombsight and were convinced that they could drop a bomb in a pickle-barrel as the propaganda line went, from 30,000 ft. They were certain that four-engined heavy bombers could take out ships at sea too. Pre-war testing made it look highly plausible.

But that's a far cry from the battlefield. In the actual Pacific War B-17s and B-24s dropped thousands of tons of bombs at Japanese ships. From the point of view of bombs carried and bombs dropped, which is all some people think actually matters for a bomber, they were far superior to the D3A or the SBD. But they sunk vastly fewer ships. Once actual fighting started they found out what really worked and what really didn't. In the Pacific, the B-17s and B-24s were good for recon and submarine patrol, or bombing the occasional airfeild, but that's about it. When it came to sinking ships, the D3A worked. So did the SBD. So did the B5N, even though it was definitely obsolescent. So did the completely obsolete Swordfish under the perfect conditions, but Swordfish were well past their heyday by the time of Pedestal. With all due respect to the Italians, the IJN was a far cry more well organized and dangerous than the Regia Marina. And the RN learned this the hard way off of Ceylon in April 1942.

 

[Shortround6]

By 1942 bombs were better, British are still behind. The British 1000lb GP bomb held about 33% explosive by weight. The British MC bomb carried about 47% explosive by weight. But it doesn't show up in numbers worth counting until 1943 the tail fin design was not finalized until March of 1943. German 500kg SC bomb held 551-573lbs of explosive or about 19% more than the British 1000lb MC and about 68% more explosive than the British 1000lb GP bomb. German 500kg SD bombs varied but some would be just under 400lbs of explosive. The German SD bombs, depending on version were semi armour piercing. Best (with less explosive) could penetrate a 50mm armour deck at a 60 degree angle (30 degrees from vertical but height/impact speed not given.

Many dive bombers traded fuel for bombload. SBDs had great range with no bomb or with the 500lb bomb, with the 1000lb bomb range wasn't so great. SBD-3 manual says 100 gals with the 1000lb bomb, 140 gallons with 500lb bomb and 260 gallons with no bomb. Gross weight may have been changed (raised) later. This is for the SBD with protected tanks and armor, manual also gives fuel capacities without armor and protected tanks.

 

[Schweik]

It's a lot better to still have the option to be able to hit ships with 500 lb bombs when they are far away (and retaining the capability of hitting them with 1,000 lbs bombs when they are close) than to be limited to less than half of that effective range with any bomb, like the Swordfish (and I'm talking to you too Ju 87).

With Naval strike aircraft, that extra range is extra important especially when tangling with an opponent like the IJN who definitely won't be confused during a night time naval engagement and have plenty of 20,000 yard range type 93 "Long Lance" torpedoes ready to go.

The 1,100 mile range on the SBD translated to about 250 mile effective range for a strike (350 for scouting). To me that suggests the effective strike range for a Swordfish is closer to 100 or maybe 120 miles. That is within fairly easy distance for a ship to move in a few hours. A few Japanese destroyers could wreak havoc on a British fleet like at Pedestal.

 

[Shortround6]

When evaluating bombers you also have to consider the targets. B-24s and B-17s may have sucked at bombing moving ships.
But Vals/Ju-87s/SBDs would have sucked trying to bomb factories 300-500 miles away from bases.

They may have gotten hits but the loss rate would have been horrendous.
Dive bombers work great against small, high value targets where you can trade several (or more than several) planes for single ship or bridge or other high value point.
They also work great against 2nd class AA systems. Or 3rd class.

The B-17s and B-24s (and the British bombers) forced the Germans to build thousands of large AA guns and fire control systems and fire thousands of shell per bomber shot down.

Dive bombers wind up within range of even infantry machineguns (at least for a few seconds) so you can take out a lot of dive bombers using small (20-40 mm) automatic guns.

Trying to be too simplistic in comparing planes wind up with rather useless comparisons.
If you are trying to compare bombers attacking strategic land based targets then range and bombload are good starting points.

BTW for a starting point on dive bombing/low level bombing see the July 24-28th 1945 attacks on Kure Japan. The US lost 133 planes due to enemy action and accidents. Number damaged unknown.
And basicly Japanese light AA sucked.

 

[Schweik]

I was speaking specifically about the Pacific Theater - B-17s and B-24s were used over and over again to attack Japanese warships, right to the end of the war, and they missed over and over and over again, despite dropping thousands of tons of bombs. For the most part all they ever killed was fish. So for those people who are routinely so simplistic as to base their entire evaluation of a bomber on the bomb load, I'd say read up on that reality.

The merits of Strategic bombing per se as distinct from Tactical bombing is a completely different debate, and this thread is derailed enough already - but I will note that the Germans had great success with their Stuka dive bombers in the MTO until probably the third quarter of 1942, when they had become no longer viable (not due to AAA so much as because of enemy fighters). Because while an accurate bomber and maneuverable, the Stuka was slow as molasses on a cold day. But they continued to be quite useful on the Russian Front right up until the end of 1944 if I recall correctly, and in both cases (and others like in the Battle of France) they proved decisive in various battles not from high loss attacks on high value targets like Capital ships or even bridges, but against much more prosaic targets like troop concentrations, tanks and artillery.

The US had similar but somewhat lesser success with the A-36, and the DAF in general with fighter bombers flying in low-level attacks and sometimes a semi- dive-bomber role.

Similarly in the Pacific, dive bombers including some unlikely specimens, were used to attack troops, as were fighter bombers and fast twin engined bombers. That was the preferred method of attack, because level bombing usually just didn't work. At least not in that Theater.

Dive bombers, Kure notwithstanding, actually tended to have pretty good survival rates overall compared to most level bombers, though it depended in part on the training level of the crews. Naval crews did much better with SBDs both offensively and in terms of attrition than Army or Marine crews.

 

[muskeg13]

Billy Mitchell arranged a series of stunts where B-17s were intercepting and dropping bombs on the decks of ships at sea. The government spent a half billion dollars developing the supposedly miraculous Norden bombsight and were convinced that they could drop a bomb in a pickle-barrel as the propaganda line went, from 30,000 ft. They were certain that four-engined heavy bombers could take out ships at sea too. Pre-war testing made it look highly plausible.

Impossible. Mitchell was court martialed in 1925 and put out of the service. He died in 1936. The Army Air Corps didn't receive their first 13 YB-17s until 1937. I think you are mixing up air power demonstration tests. Mitchell's "stunts" were conducted in 1921 against stationary ships from relatively low altitude. During the 1930s, there were a number of airplane vs ship "maneuvers" conducted by both the Air Corps and the Navy, including intercepting and dropping flower sacks and water bombs on moving warships, from low altitudes. The long-range search and ship bombing capabilities of the new B-17s were highlighted several times in 1937 (several hits scored from an altitude of 400 feet) and culminating in the May 1938 interception of the Italian liner Rex approximately 700 miles of off the U.S. east coast. This prompted a USN protest that the Army (Air Corps) was getting too much into USN business and all Army aircraft were restricted to operating no more than 100 nautical miles off the U.S. coasts which remained in effect until WW2 broke out. The first Norden bomb sight wasn't installed in B-17s until 1939.

During WW2, there were several examples of U.S. Army medium altitude bombers (including B-17s and B-24s) successfully attacking ships, but usually these were either stationary or very slow moving merchant vessels in restricted waters and certainly were not from 20,000 or 30,000 feet. The Army ship killers were 5th Air Force B-25s and A-20s using 500 pound bombs in skip and mast height bombing, like during the Battle of the Bismarck Sea.

 

[Peter Gunn]

I would also note, although I can't find the source right at the moment, that AAF B-17's doctrine was to approach any moving ship from the stern with at least 12 bombers in a line abreast formation in a bit of a Vee shape. The idea was that once the bombs were released it didn't matter which way the ship turned, it would be turning into one of the sticks of bombs dropped ergo it would have no safe maneuver left open to it. As memory serves, you can count on one hand how many times it was used in practice. In fact, it was rarely practiced in training so there's that.

At Midway, Col. Sweeney showed up over KdB in the 8 o'clock hour with 15 B-17's which he divided into 3 groups, I suppose he hoped to hit more than just one carrier and as it was, both Hiryu and Soryu were bracketed by near misses. It might have been interesting if he had used all 15 to attack one carrier in the formation above, but again, the USAAF didn't practice it very much so he probably felt he was getting better odds of a hit if he went after more than one CV.

 

[Juha3]

I don't expect him to know the details of all the hits, only of the ordnance that was carried. The luftwaffe knew the position of Illustrious when she was first attacked by Stukas and it was less than 100nm miles from the Luftwaffe bases in Sicily and no further than when Illustrious was in Malta Harbour. This map shows the distances involved and the risks that the RN had to run to escort a convoy to Malta:

https://images.squarespace-cdn.com/...MshLAGzx4R3EDFOm1kBS/IMG_0469.PNG?format=750w

In this interview the Stuka Squadron Commander that attacked Indomitable states that they carried 1 x 500kg and 2 x 250kg bombs each:

This is really basic, if the target is in the dock, one knows where it is when he takes off and when he arrives over it. It the target is a ship in the open sea capable to 30 knots, even if its position is known at the take-off it will be somewhere else when one arrived over it if it is not circling around. Even if one has a shadower to watch it it might turn to whatever direction during inflight and especially in the case of a carrier a CAP might got the shadower at any time and the position given by the shadower might be somewhat off. This latter was a thing that U-boats fairly often complained. So when taking off to attack targets in the open sea it is better to have more fuel reserves than in the case of attacking a fixed target.

 

[Juha3]

It looks like Indomitable was indeed hit by two 500 kg bombs dropped by Stukas of StG 3. The same unit also scored four hits on the HMS Warspite during the earlier operation Excess, but it too failed to sink. Later the same Stukas managed to damage the light cruiser HMS Southampton badly enough that it was scuttled. They never sunk any capital ships as far as I could determine.

This is footage of the actual attack here:

...
You did not bother to read the Armoured Aircraft Carriers link I posted in my message Swordfish vs Devastator? The main point in it to confirm the size of the bombs was "It was pointed out the 14-in hole reported in the 60lb steel plate alongside the forward lift was too small for a 1100lb (500kg) SD-style bomb. Intelligence recorded the diameter of this weapon was 18in, with an older style being 15.5in.

Only the 550lb (250kg) SD bomb had a 14in diameter."

 

[Schweik]

Impossible. Mitchell was court martialed in 1925 and put out of the service. He died in 1936. The Army Air Corps didn't receive their first 13 YB-17s until 1937. I think you are mixing up air power demonstration tests. Mitchell's "stunts" were conducted in 1921 against stationary ships from relatively low altitude. During the 1930s, there were a number of airplane vs ship "maneuvers" conducted by both the Air Corps and the Navy, including intercepting and dropping flower sacks and water bombs on moving warships, from low altitudes. The long-range search and ship bombing capabilities of the new B-17s were highlighted several times in 1937 (several hits scored from an altitude of 400 feet) and culminating in the May 1938 interception of the Italian liner Rex approximately 700 miles of off the U.S. east coast. This prompted a USN protest that the Army (Air Corps) was getting too much into USN business and all Army aircraft were restricted to operating no more than 100 nautical miles off the U.S. coasts which remained in effect until WW2 broke out. The first Norden bomb sight wasn't installed in B-17s until 1939.

You are right I conflated the two series of tests (or stunts or maneuvers or whatever you want to call them) and with the actual wartime use of the big bombers. - the point being that petty interservice rivalries aside, the US had wildly optimistic notions (particularly pre-war) about the accuracy of their heavy bomber fleet, and especially for the Pacific, in the notion of it's efficacy as a high altitude level bomber against ships. They could hit a moving cruise liner with a sack of flour 700 miles offshore, but during the war, even when they were very big ships sitting at docks, the heavy bombers had trouble hitting them. For example the IJN Battleship Ise, after already being hit by four bombs dropped by USN Corsairs and Helldivers, was attacked while at dock by 18 x B-24s, without a single hit being scored. Throughout the war and right up to the end, heavy bombers were used to attack shipping and repeatedly failed, with only a few successes - despite the vast quantity of bomb tonnage dropped.

During WW2, there were several examples of U.S. Army medium altitude bombers (including B-17s and B-24s) successfully attacking ships, but usually these were either stationary or very slow moving merchant vessels in restricted waters and certainly were not from 20,000 or 30,000 feet. The Army ship killers were 5th Air Force B-25s and A-20s using 500 pound bombs in skip and mast height bombing, like during the Battle of the Bismarck Sea.

Yes I did mention this upthread - the mast-head and skip-bombing turned out to be quite effective, especially in conjunction with heavy strafing, though it wasn't used with as much success against the really heavily defended ships as dive bombing.

They did actually use B-17s in some low-level bombing raids with some success in New Guinea on a couple of occasions. And in the MTO, the B-24 proved quite efficient at wrecking airfields from medium altitude so long as they were well protected by fighters. Against better protected targets like Ploesti though as we know, the low level strikes proved extremely hazardous for the bomb crews.

 

[Schweik]

...
You did not bother to read the Armoured Aircraft Carriers link I posted in my message Swordfish vs Devastator? The main point in it to confirm the size of the bombs was "It was pointed out the 14-in hole reported in the 60lb steel plate alongside the forward lift was too small for a 1100lb (500kg) SD-style bomb. Intelligence recorded the diameter of this weapon was 18in, with an older style being 15.5in.

Only the 550lb (250kg) SD bomb had a 14in diameter."

I stand corrected.

 

[Juha3]

The IJN Vals were not exceptionally accurate and we have to remember that attacking nearly unarmed merchant vessels allowed aircraft to drop from very low altitudes. This is a summary, from Lundstrom, of the very similar attack on USS Sims and the tanker Neosho, which had a maximum speed of only 14 knots.

"By 1115, Lt. Cdr. Takahashi determined there definitely was no American carrier nearby and released the carrier attack group and its escorts to return to the carriers. His dive bombers would attack the oiler and accompanying destroyer. At 1126 he began his attacks. He led four carrier bombers against the destroyer Sims, and they scored three direct hits on the radically maneuvering tincan. The remaining thirty-two carrier bombers made slow, deliberate dives against the Neosho and inflicted at least seven hits, including a flaming crash by one of the Zuikaku carrier bombers. Noon found the Neosho adrift without power and perilously listing 30 degrees to starboard. Only her extensive compartmentation and tanks kept her afloat. For the loss of one carrier bomber, the Japanese had sunk one destroyer and fatally crippled a fleet oiler. "

Unlike Hermes, which sank rapidly, the crew of Neosho had time to assess the damage and number of hits. 32 bombs dropped and ~7 hits on a lightly armed 14 knot tanker versus ~35 bombs dropped and 6 hits on Illustrious moving at 24 knots and having some degree of CAP and a lot more flak. Hermes was probably hit ~10 times.

USS Neosho was a fleet oiler armed with four 5"/38 DP guns and four 20 mm Oerlikon.

 

[special ed]

I may have mentioned on another thread, my late father in law was a B-17 crew chief in the 19th BG. He told me some pilots conducted skip bombing with the B-17. They painted two horizontal white lines inside the pilot's windscreen, one for 500 lb the other for 1000lb bombs. By attacks, they determined the position of the white lines by speed and height, so that when at the proper speed, with the right size bomb, the corresponding white line was at the ship's water line the bomb was released.

 

[Schweik]

That's really interesting! I read about some low-level attacks they did with B-17s against Lae (I think) in New Guinea which were successful. This at a time when attacking that base was almost a death-sentence for many strike aircraft (and escorting fighters too).