What is the best of these four Dive Bombers?

[oldcrowcv63]

Rich,

Thank you for taking the time to post this extensive and eloquent treatise on bombing. I suspect I wasn't the only one here diligently searching the web for exactly the concise tutorial you've provided us here!

Bravo!

Late entry: Based on the above, it would seem:

Vultee A-31/35 Vengeance: Equipped with dive brakes, delivered ordnance in a high angle dive (>70 degrees) using dive brakes, centerline, internal bomb releases using an extending bomb bay crutch to move ordnance clear of the prop arc. Conclusion: A proper dive bomber.

North American A-36 Apache: Equipped with dive brakes, wing mounted bombs (clear of the prop arc at release), delivered ordnance in a high angle dive (>70 degrees) using dive breaks: Conclusion: a proper dive bomber, perhaps slightly handicapped by off-center-line stores position.

As Rich points out above, the TBF/M and F4U, would appear not to be proper dive bombers for a couple of design and weapon delivery shortcomings.

I remain curious about Kenney's apparent distaste for dive bombers and dive bombing

 

[T Bolt]

This is doubly interesting because both Kenney and Doolittle were reputed to be among the most technically savvy generals! What did they know about these aircraft (B-24 / A-35) or the dive bombing technique that turned them off to them/it? Do you have a reference for Doolittle's antipathy to the Liberator? I'd like to read more on that. B-24 and PB4Y has always been a favorite of mine, but don't know much about them other than some very favorable operational accounts

I read it in a book 12+ years ago but don't remember which one. I'll have a look around and see if I can find it. The other source of the info was my father. He was with the 490th bomb Group, 8th Air Force and when I quoted what I had read to him about Doolittle, he went off on Doolittle using very colorful language. Apparently he too knew that Doolittle was the cause of the B-24s being moved to the 15th Air Force. My fathers colorful language was due to the fact that he was moved to Italy along with the Liberators and went from being quartered in a cozy heated quonset hut to living in a tent.

 

[davebender]

Interesting material but it fails to discuss the most important point.

A bombers purpose is to put bombs on target. That's what counts, not delivery angle or tonnage dropped which misses the target. What was TBF accuracy when "Glide Bombing"? What was SB2C accuracy when "Dive Bombing"? If the TBF can place bombs within 30 meters of a target I don't care if it's flying upside down when bombs are released.

The standard for comparison.
HyperWar: The Battle of Britain--A German Perspective

Ju87B-1 (the model in service in 1939-1940), "was to prove effective in the hands of expert pilots, who, in dives of eighty degrees to within 2,300 feet from the ground, could deliver a bomb with an accuracy of less than thirty yards. Even average pilots could achieve a twenty-five percent success rate in hitting their targets

Badass of the Week: Hans-Ulrich Rudel
Rudel claims (in "Stuka Pilot") he could always hit within 10 meters of the target when flying a Ju-87. It's a good thing for us Germany didn't find a way to clone him.

 

[Jabberwocky]

Chris Bellamy's 'The evolution of modern land warfare: theory and practice' says that a Ju-87 "in a dive could put 25% of their bombs in a 50 metre diameter circle". (Pg 85)

There is no doubt that a Ju-87 COULD deliver a bomb in a 30 yard circle, but I don't believe that figure is properly reflective of the CEP of the Stuka in combat.

 

[Jabberwocky]

Some more information, gleaned from another forum:

"A study on of fighter-bomber attacks on bridges over the Savio River in Italy during the spring of 1944 found a sharp drop-off in bombing accuracy directly correlated with the intensity of flak fire. With no flak, P-47s could put half of their bombs within 180 feet of their target and required 30 bombs to score one hit. With medium flak, accuracy dropped to 300 feet, requiring 84 bombs per hit; with heavy flak, it was 420 feet and 164 bombs."

"Later research found that it took an average of 3,500 bombs or 800 rockets to get a single tank hit. ... After the Normandy fighting, the Operational Research Section of Montgomery's 21st Army Group combed the battlefield and examined 301 tanks and self propelled guns left by the retreating Germans. Only 10 were found to have been hit by air-to-ground rockets. On close examination, many of the vehicles proved undamaged."

Air Power, Stephen Budiansky

So Stuka CEP: 25% within 164 ft, but no indication of whether this is opposed or unopposed
P-47 CEP: 50% within 180 feet unopposed, 50% within 300 feet to medium flak opposition, 50% within 420 feet to heavy flak opposition

I'm downloading USAF study 163 at the moment, might be some more answers in there.

 

[oldcrowcv63]

Flight Deck Width dimensions:

6/4/42: IJN Soryu: 85.3 ft
6/4/42: USS Yorktown, CV-5: 86. ft (although I have seen flight deck width quotes up to 114 ft)
1/10/41: HMS Illustrious: 95 ft.

The targets are all manuevering at about 30 knots when hit by multiple bombs carried by respectively:

Douglas SBD Dauntless (9 aircraft) (3 hits)
Aichi Type 99 D3A 'Val' (7 aircraft) (3 hits)
Junkers Ju-87 (10 aircraft) (6 hits) revised to: (30 aircraft) (6 hits)

(wikipedia claimed 10 Ju-87s accoounted for the 6 hots...)
In all three cases, the aircraft were flown by essentially experienced crews with the USN's VB-3 perhaps slightly less well tuned compared to Fliegrcorps X and the Hiryu's Kanbaku unit but I suspect there was really little difference in the general skill level of the three units. (VB-3's commanding officer, Max Leslie had a malfunction that resulted in loss of his bomb so his particular expertise was lost in this attack)

It seems to me that the results are similar enough to suggest an essentially common high level of skill on the part of the three prime practitioners of this particular trade: USN, IJN and Luftwaffe, as well as a fair degree of parity in the accuracy of each platform. Which aircraft would I want to be in? A Grumman A-6 Intruder thank you very much... but failing that, I'd say without a doubt or hesitation, a Douglas SBD Dauntless.

Late revision: Reading Ian Cameron's Wings of the Morning he states 30 Stukas bombed the Illustrious and scored the 6 hits that tore up the RN Carrier. That suggests no essential difference in the performance of the three nation's flyers or that Flieger Corps X's flyers and JU-87s may have been slightly less effective. However, the Illustrious enjoyed little to no CAP defense while the 7 Vals were the survivors of a murderous interception by a dozen of Yorktown's veteran composite VF-3/-42 squadron. Three months later the HMS Ark Royal was faced with a similar attack and escaped essentially unharmed. She was defended by about 7 Fulmars which collectively fought off a raid by some 18 Ju-87 and ~9 Me-110 escorts. Another 4 Fulmars appear to have fought off a similar sized formation. Fliegercorps X had apparently suffered grievous losses in the interim and its effectiveness was seriously degraded.

 

[renrich]

Many thanks, Rich, for your so clear post about the definition of dive bombing. From "Corsair" by Barrett Tillman, pages 79, 80, 81. Credit for the field mod which created the Corsair dive bomber is generally given to VMF-111 which delivered bombs to Mille in the Marshalls. "Thus began the F4U's unplanned career as a dive bomber."

Without going into all the details( because my typing is so laborious and poor) the Marines were bombing gun implacements which required a lot of accuracy. The standard of accuracy was called the CEP( Circle of Error Probability) The CEP of the SBD was estimated at 175 feet, the Corsair's at 195 feet. The Marines found that lowering the wheels of the Corsairs helped control the speed in a dive. Bombing a 25 foot circle, SBDs could expect to obtain 1.4 per cent hits, the Corsair 1.1 per cent. Attacking a 250 foot circle the SBDs recorded 75.1 per cent while Corsairs scored 68.2 per cent. "Unlike the SBD, which best performed in a 70 degree dive, experimentation showed the F4U could bomb at angles up to 85 degrees."

I always wondered how the Corsair was able to dive bomb with out the gear to extend the bomb away from the prop. I have no doubt that as Rich mentioned the Corsair was not routinely used as a steep angle dive bomber.

 

[oldcrowcv63]

Bombing a 25 foot circle, SBDs could expect to obtain 1.4 per cent hits, the Corsair 1.1 per cent. Attacking a 250 foot circle the SBDs recorded 75.1 per cent while Corsairs scored 68.2 per cent. "Unlike the SBD, which best performed in a 70 degree dive, experimentation showed the F4U could bomb at angles up to 85 degrees." I have no doubt that as Rich mentioned the Corsair was not routinely used as a steep angle dive bomber.

Ok Ren, I'll give you that the F4U was very accurate as a dive bomber poseur but was it a proper dive bomber More to the point if you were an SBD and had a daughter would you let her marry an F4U?

 

[buffnut453]

Dunno but if you were a TBM and your daughter married an F4U, would their kids look like this?

Of course they'd have to emigrate...presumably for embarrassing the TBM and F4U families...sounds like a Shakespeare play!

 

[oldcrowcv63]

Without a doubt But whereever would they go?

I think there are the makings of a new and different thread in this dialogue. Or to quote: Monty Python's Flying Circus: "And now for something completely different!"

 

[renrich]

Actually, the Corsair was originally designed to be a bomber as well as a fighter. The XF4U had bomb compartments in the wings which is where the guns wound up reposing.

 

[Shortround6]

Uh, I believe that was for small bombs to be dropped on enemy bomber formations?

Not quite the same thing

 

[oldcrowcv63]

Actually, the Corsair was originally designed to be a bomber as well as a fighter. The XF4U had bomb compartments in the wings which is where the guns wound up reposing.

That's an astonishing revelation for an aircraft essentially designed in 1938! I would imagine it to represent one of the earliest conceptualization of the modern fighter bomber of which I am aware!

From Wikipedia:

"In February 1938 the U.S. Navy Bureau of Aeronautics published two requests for proposal for twin-engined and single-engined fighters. For the single-engined fighter the Navy requested the maximum obtainable speed, and a stalling speed not higher than 70 miles per hour (110 km/h). A range of 1,000 miles (1,600 km) was specified.[8] The fighter had to carry four guns, or three with increased ammunition. Provision had to be made for anti-aircraft bombs to be carried in the wing. These small bombs would, according to thinking in the 1930s, be dropped on enemy aircraft formations."

Whatever the motivation for its design, it certainly wildly exceeded such a primitive inceptual notion as a bomb-dropping interceptor. For Vought, perhaps it wasn't the large conceptual stretch I had imagined. Apparently, the Vought F3U (2-place biplane fighter predecessor of the F4U fighter) evolved into a dive bomber: the biplane SBU itself the predecessor of the SB2U Vindicator! IIRC, the RN FAA also looked at the SB2U to complement(?) its Skua fighter-dive bombers including 4 forward firing wing mounted RCMG.
It would appear the FAA regarded it as less capable or desirable than its own roughly equivalently powered Fairey Swordfish!

 

[Readie]

As far as I can gather, Renrich was correct, the TBF was not employed as a dive bomber (at least typically). My statement that it was, is suspect, since I have only been able to find a couple of references to its potential use as a dive bomber but no instances of its actual use. I thought the best possibility might be chichi jima, but haven't found any verification of that. The use of the landing gear as a dive break is mentioned on a number of sites and I can assure you that Grumman iron works would be capable of producing landing gear assemblies with that kind of strength, so perhaps it was occasionally used in that manner.

Would I want to do it? Personnally, I don't like the idea. Let the F4U studs adopt that tactic. Evidently the F4U Main gear doors (purpose designed?) acting as ersatz dive breaks:

WHINE about the sair and hellcat [Archive] - Ubisoft Forums

with F4U dive methodology described in this forum in a lengthy post reproduced from FAA test pilot Capt Eric Brown's Wings of the Navy.

Scrivner's TBF/TBM Avenger in action Series pub states that a weapon delivery on a moving vessel was to attack in a 30-45 degree dive to a release point at 500 ft or less altitude. An intervalometer was used to release the bombs (presumably a stick of 4 x 500 pounders) in a string 60-75 feet apart.

Thanks Mal
John

 

[oldcrowcv63]

I must say, Rich Leonard really clarified the situation wrt to the TBF for me with credit for an assist to renrich.