1936 to mid-42: fast 1-engined bombers instead of slow types?

[Shortround6]

By late 1944 a British division had 72 Bofors guns

Not quite as fancy or high tech but with an assortment of 20mm guns

Things were a lot less fun for the dive bomber pilots than when this was the standard light AA gun.

I think in the Battle of France there were 4 of these per battalion?
And there were a few tripods in each company.

No extra guns, just a few tripods to use for AA using some of the guns from the squads/platoons.
After France and when the gun supply got better they put two Bren guns on the light trucks, German pilots shook in their flying boots when faced with those.

 

[Shortround6]

And yet, dive bombers were used by US Navy to the end of the war.

The stand off anti-ship weapons could be very effective, but they seem to have found countermeasures against them that also worked.

A lot depended on your enemy.

US got away with using dive bombers against the Japanese navy (and Islands) because.

1, the Japanese never developed VT (proxomity) fuses.
2. The Japanese never used a heavier light AA than the

25mm Hotchkiss
3. the Japanese didn't use may 20mm guns and their 13mm AA gun was another Hotchkiss.

30 round box magazines.

 

[EwenS]

I have read reports of the Albacore in NA and the MTO being used for attacks on supply dumps and airfields, as well as attacks against troop concentrations, both day and night. At night they were sometimes directed to the target by 1 or 2 Wellingtons acting as pathfinder/illumination flare droppers. During the daytime attacks they were usually escorted when possible. I read in one source (I do not remember which) that ~90% of the ordnance dropped by Albacore squadrons in the NA and MTO campaigns occurred when flying from shore bases.

It was the other way around. The Albacores of 826 squadron began flare dropping operations for the Wellingtons in Sept 1941. They operated from forward airfields with flights rotating back to their main base in the Canal Zone every few weeks for deeper maintenance. The Wellington squadrons were based in the Canal Zone. 821 squadron joined in in 1942. Targets were places like Benghazi. Each Albacore could carry up to 24 flares.

 

[Wild_Bill_Kelso]

The US was using the A-36 with success (until the wing stress problem) in Italy in 1944 against excellent German ground defenses and (when available) fighters, and they were also using P-40s and P-47s, and sometimes P-51s and P-38s, as fighter bombers. In particularly difficult terrain. Again, with success. The British had success with Hurricanes and P-40s in the Wesdtern desert, P-40s in Italy, and Typhoons (albeit with heavy losses) and (especially) Tempests; and the US with P-47s etc. in NW Europe as well. Germans had pretty good luck with FW 190 Jabos in spite of some the formidable British AAA you mention, plus US kit like this

Speed seemed to be a very important factor in survival for any kind of Tactical or Operational bombing in the later part of the war. Tactics, skill and pilot training also very important.

 

[Shortround6]

The US was using the A-36 with success (until the wing stress problem) in Italy in 1944 against excellent German ground defenses and (when available) fighters, and they were also using P-40s and P-47s, and sometimes P-51s and P-38s, as fighter bombers. In particularly difficult terrain. Again, with success. The British had success with Typhoons and (especially) Tempests and the US with P-47s etc. in NW Europe as well. Germans had pretty good luck with FW 190 Jabos in spite of some the formidable British AAA you mention, plus US kit like this

Fighter bombs often were NOT dive bombing.
Most of the British successes with Typhoons and Tempests were NOT dive bombing.
The FW 190 Jabo's were NOT dive bombing.

With hundreds if not thousands of missions flown incidences can be found for just about any attack profile but the 1939-41 Stuka style attack profile was going away.

Large groups (several squadrons) doing formation attacks or sequences of follow the leader and taking a number of seconds to descend while the dive brakes controlled the decent speed. Doing 4-5 G pull outs pretty much guaranteed the pullout fight path.
Fighter bombers spent much less time in the AA gunners sights. Not just because of the speed but because using terrain or the low altitude to mask the flight path from the guns.
If you do a high speed dive (like no dive brakes) you can be exposed for less time but you also have less time to aim/correct and you have to drop the bomb/s from higher up so you can pull out. Both factors affect accuracy.

Many of these fighter bombers dropped bombs while descending or even in a dive, and unfortunately the term "dive bomb" is rather loose. The Stuka, the Vengeance and few others not could, they were intended to bomb at a 90 degree angle or close to it. The SBD illustrates the problem, it was intended to dive at 90 degrees to the ground. However the flight path was closer to 80 degrees, the wings provided lift and unless the dive bomber actually flew at higher than 90 degrees or had a wing with an odd incidence or a special airfoil the plane was not going to do 90 degree flight path.
If a plane dives at 60 degrees nominal the impact zone will be much longer than it is wide. the shallower the angle the bigger the impact angle.
Skill/ practice helps but only so much. Higher speeds affect accuracy.

 

[Wild_Bill_Kelso]

I agree with most of that, and I never said that fighter-bombers were mostly or exclusively doing dive bombing, it's just that they could and did do 'low angle' dive bombing, for some kinds of targets. Apparently per above P-47s did vertical dive bombing. They also did things like skip bombing for example, and a lot of just ordinary level bombing but at low altitude.

I think coming in low is one of the key factors for better accuracy. Speed is obviously a key factor for being able to survive the approach and egress.

What we know is that fighter bombers all but replaced bombers as such for tactical warfare toward the end of WW2, and this has continued to this day with a few exceptions.

The emphasis on bomb load was far less useful, in the long run, than the emphasis on performance and agility that a fighter bomber had.

 

[Shortround6]

The emphasis on bomb load was far less useful, in the long run, than the emphasis on performance and agility that a fighter bomber had.

To some extent.
The late war Allied fighter bombers could carry 2000lbs or more, Granted the range may have been rather limited.
But what you could do with 2000hp plus fighter was way different that what you could do with 1000-1200hp bombers or fighters in 1939-41.
Hurricanes and Whirlwinds were often bombing France and the low countries with pairs of 250lbs bombs. Typhoons after D-day were using pairs of 1000lb bombs.
Typhoons were also carrying hundreds of pounds more armor. Amazing what you can do with Spitfires as top cover

 

[don4331]

I agree with most of that, and I never said that fighter-bombers were mostly or exclusively doing dive bombing, it's just that they could and did do 'low angle' dive bombing, for some kinds of targets. Apparently per above P-47s did vertical dive bombing. They also did things like skip bombing for example, and a lot of just ordinary level bombing but at low altitude.

I think coming in low is one of the key factors for better accuracy. Speed is obviously a key factor for being able to survive the approach and egress.

What we know is that fighter bombers all but replaced bombers as such for tactical warfare toward the end of WW2, and this has continued to this day with a few exceptions.

The emphasis on bomb load was far less useful, in the long run, than the emphasis on performance and agility that a fighter bomber had.

Those P-47 numbers - starting at 190mph (probably no faster than Ju.87), finishing at 270mph - close enough to 240mph average = 352ft/s
4k' decent @ 350'/s = 11 seconds from push over, re-locate target, line up, drop ordinance and finish pull out. To accurately hit target within that time period is pretty impressive (hence 100 yards CEP).
But is 50% of ordinance hitting within 100yds good enough with pair of 1k lbs bombs? Is it still good enough with pair of 250 lbs ones??

 

[Wild_Bill_Kelso]

To some extent.
The late war Allied fighter bombers could carry 2000lbs or more, Granted the range may have been rather limited.
But what you could do with 2000hp plus fighter was way different that what you could do with 1000-1200hp bombers or fighters in 1939-41.
Hurricanes and Whirlwinds were often bombing France and the low countries with pairs of 250lbs bombs. Typhoons after D-day were using pairs of 1000lb bombs.
Typhoons were also carrying hundreds of pounds more armor. Amazing what you can do with Spitfires as top cover

P-40s were carrying 2,000 bomb loads in 1942. Depending on how you rate them, those are 1,200 hp aircraft, up to maybe 1,400 or 1,500 hp in a pinch.

From RAAF pilot Jack Doyle

https://www.3squadron.org.au/subpages/AWMDoyle.htm

"Getting on to your first point I don't think everyone did come to like them, because I know some people that would never do a three-point landing with it, or attempt to and they'd do tail-down wheelers. But I think they were an outstanding aircraft for the job you were doing. I went right through the war on Kittyhawks although I was promised Mustangs in 450 Squadron. They didn't give me Mustangs but they gave me one personally to play with to sort of abate my wrath a bit, but actually the Kittyhawk was better than the Mustang for doing the job that the Kittyhawks were doing. It is very robust. It is very solid. It has a minimum amount of plumbing for radiator and oil and that sort of thing - the Mustang has a radiator way back and there's a lot of plumbing and you can get bullets through the pipes which causes you problems. But the Kitty was very strong and robust and it had very good armament. It carried 2000 pounds of bombs. There were twin-engined three-crew aircraft in the Middle East that only carried 1500 pounds of bombs. We carried 1500 pounds of bombs on the Kittyhawk as a perfectly normal bomb load. "

Oh yes, it did. I mean - you can laugh at this - we were climbing at 200 feet a minute with a bomb load - you're modern stuff goes up vertically - but they didn't have much of a rate of climb but I carried the first 1000 pound bomb on the Kittyhawk and in subsequent operations the more experienced pilots which sometimes flew the newer aircraft, a better aircraft, they carried 2000 pounds and the remaining six or so in the squadron would carry 1500 pounds; a normal load is 1 500 pounds but we carried 2000 for shipping.

From interview with RAAF pilot (and squadron leader) Brian Eaton:

Right. How effective was the Kitty in that role of ground attack aircraft?

I think it was very good. It could take an awful lot of punishment and still get you home. It was a very, very –. You had six .5s, could carry two 250-pounds – later two 500-pound bombs – and still later carried a thousand pound bomb and two 500- pound bombs. So almost like a light bomber. Oh, it was a very good aircraft.

 

[tomo pauk]

But is 50% of ordinance hitting within 100yds good enough with pair of 1k lbs bombs? Is it still good enough with pair of 250 lbs ones??

Units (flight, squadron, what ever the people were using) of aircraft should attack a target. There should be a lot of fun in these 100 yds with a squadron (12-16 A/C usually) dropping their bombs in a quick succession.
With more powerful engines, we'd look at at least 4 x 250 lb bombs or 2 x 500 lb (or their metric equivalent),

 

[EwenS]

I read in one source (I do not remember which) that ~90% of the ordnance dropped by Albacore squadrons in the NA and MTO campaigns occurred when flying from shore bases.

Hardly surprising when you think about it.

There were no carriers operating east of Malta between the end of May 1941, when Formidable was bombed off Crete, and mid-1943, when Illustrious & Formidable arrived to cover the landings in Sicily. So we had:-

826 - left in Egypt when Formidable went for repairs in the USA.
829 - Formidable's second squadron operated from shore May-July 1941.
815 - left at Malta in Jan 1941 when Illustrious went for repairs in the USA, it later moved to Egypt where it received Albacores to operate alongside its Swordfish.
821 - sent to Egypt at end of 1941 via the Cape.
828 - sent to Malta in Oct 1941 (ferried on Argus & Ark Royal)
830 - formed at Malta in July 1940 from a training squadron. Main equipment was the Swordfish but also used the Albacore.

These squadrons moved forward as North Africa was cleared, including to Tunisia & Algeria in 1943, and eventually disbanded between March and Oct 1943.

At the western end and other than the ferry operations supplying replacement aircraft to Malta, it was Aug 1942 during Operation Pedestal, convoy operation to Malta, before any Albacores were seen, and then mostly from the carriers. So Operations Torch, Husky & Avalanche. Formidable's 820 squadron was the last operational Albacore carrier squadron in the Med, during Operation Avalanche in Sept 1943.

 

[Wild_Bill_Kelso]

Those P-47 numbers - starting at 190mph (probably no faster than Ju.87), finishing at 270mph - close enough to 240mph average = 352ft/s
4k' decent @ 350'/s = 11 seconds from push over, re-locate target, line up, drop ordinance and finish pull out. To accurately hit target within that time period is pretty impressive (hence 100 yards CEP).
But is 50% of ordinance hitting within 100yds good enough with pair of 1k lbs bombs? Is it still good enough with pair of 250 lbs ones??

Well, lets put it into perspective. WW2 bombing, of any type, is not accurate by the standards of modern bombing with laser designated or GPS guided "smart" bombs etc.

But compared to level bombing by 'bomb trucks' like B-17s or B-24s, the CEP is closer to 300-400 meters in more or less ideal conditions. Stukas were supposed to strike targets within 25 meters. One test suggested an SBD had a CEP of about 50 meters, while F4Us operating in the same area had about 60.

So it depends on the target. But 100 yards CEP with a 1,000 lb bomb is very good for say, aircraft, artillery, soft-skinned vehicles, ammunition and most supplies. A US M65 1,000 lb bomb has a damage radius of something like 150 meters so pretty much anything unprotected on the surface is going to be wrecked by two 1,000 lb bombs striking within 100 meters.

A more hardened target like say, a bridge or a warship, or tanks, bunkers, or dug-in gun positions, might need a closer hit, but if you have a squadron of say 12 x P-47s dive bombing with that level of accuracy, chances are even a harder target is going to be in serious trouble.

 

[Wild_Bill_Kelso]

Reading a little more about dive bombing, it seems that the 53 meters CEP for SBD / 59 meters for F4U was for Marine Corps pilots in one specific campaign. Marine Corps did not have nearly as extensive training in dive bombing as the USN did, and successful dive bombing took a lot of training. Neither Marine or Air Force pilots had the kind of success against Naval targets that USN pilots did, and this also seems to have carried over against land targets. Apparently USN dive bombers achieved a CEP of as little as 15 meters as measured in some campaigns.

This is the kind of accuracy you need if you want to take out dug-in bunkers, pill boxes, tanks, or hard targets like steel bridges.

But the thing about a P-47 or F4U doing dive bombing with a little less accuracy was, they could carry twice the load, they could fly 100 mph+ faster (once the bombs were released), and they could more than hold their own against enemy fighters if intercepted. This is also true for P-40s particularly in the Pacific or China Theaters.