Why was the SBD such an effective aircraft?

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Ok, lets be candid. Here is my $.02 love it or lump it.

I'm pretty careful to be clear when I'm engaging in speculation vs. discussing facts, and I make an effort to acknowledge when I'm wrong. Certain other people here almost never admit to errors, and routinely conflate their own opinion with facts. This is usually in the service of shutting down somebody else's line of thought which is even more obnoxious. Some people can't appreciate an idea if they didn't come up with it, or if it hasn't been given their Ok as a gatekeeper.

But right or wrong there are benefits to being on the forum a long time, in terms of support.

I don't care, I gather my posts in here are rarely appreciated and usually only by a few, as I am not in lockstep on every opinion as everyone else on here. I'm also not an idiot, I am as well read and well traveled as the rest of you and I've been around WW2 aircraft since I was a kid. I'm not going just go along with being shouted down every time I post something that rubs a forum regular the wrong way for whatever arbitrary reason.

I've been accused of all kinds of ridiculous things here and I'm kind of fed up with it. But I can always just lurk / read the forum and not post. I still enjoy reading it in spite of the attitude of a few of the people. Frankly most forums have similar issues with cliques and so on which is why there are so few forums left, sadly. But I will say there are a lot of knowledgeable people here which is probably why it's still around.
 
 

I'll be candid, it's your presentation.

Need a tissue?
 
Float Scouts: The reason they usually had at least two crew was the sighting messages were sent via HF in morse code, that and the second set of eyes. Even if the extra eyes only increased the sighting accuracy or even by 25% the course of a battle might turn on it.
 
The SBD was effective in its own specialized role - dive bombing ships at sea. It was small enough to carry on aircraft carriers and carried a large enough bomb to damage or destroy capital ships when delivered in a near vertical steep dive to ensure accuracy. The USAAF found it to be far less suitable in its A-24 configuration for the type of bombing campaign required for land based operations.
Carrier conflict, with emphasis on one or two swift strikes to cripple and sink opposing fleet elements, was far different than the daily grind of attrition common to land campaigns. The SBD was just not robust enough, nor could it deliver the tonnages required to dramatically impact a land campaign. A single medium bomber could carry the tonnage of three or four SBDs farther, and with a better expectation of survival against land based interceptors. And we aren't even looking at the heavies. Land based targets tend to be spread out over a greater area than a single ship so pin point accuracy is less important to the level bomber.
In some respects, carrier aircraft are single use weapons. Look at the loss rates at Coral Sea, Midway, Eastern Solomons, etc. Could the 8th Air Force sustain operations with attrition rates that high?
 
Schweik said:
Like I said before, if they could make a Na-6 or T-6 or whatever into a 300 mph fighter with the same engine and the same field stripping you could probably have made the SBD 300 mph, maybe a little more.
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Not sure what this means, the Boomerang sure didn't use the same the engine as the NA-16, Wirraway, T-6 or whatever. The trainers used an 9 cylinder R-1340 engine with a single speed supercharger. The Boomerang used a 14 cylinder R-1830 engine with a two speed supercharger.

Please show estimates of how the SBD would gain 45-50mph in speed aside from your imagination.


Schweik said:
The SBD is probably a bit more aerodynamic than the Buffalo which is really fat. But even that plane got up to 320 mph with a 1,200 hp engine.
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You keep quoting the take-off power, the Buffalo had about 1000hp at the altitude it made best speed.

Now for our "the Dauntless can do anything" fans a little reality check.


And a few dimensions from the F6F Hellcat
Wing span 42 ft 10 in or 1 ft 4in more
WIng area 334 Sq ft or 9 sq ft more (2.7%)
Over all Length 33 ft 7in or about 7 in longer.

SO without a drastic chop job you are trying to use either a Wright R-1820 or P&W R-1830 in an airframe the size of the F6F even if a lot lighter.
The F6f could do about 302kts (347mph) at 15,000ft using about 1625hp.

It has been said that the Buffalo was rather portly and it was, however looks are a bit deceiving. Anything that is about 26ft long and as wide as the Buffalo is going to look rather tubby.
Stretch the fuselage out to 33 ft or so with the same width/depth and the plane "looks" slimmer. Yes the Dauntless is slimmer side to side through the cockpits but from top to bottom?

As to weight, the manual says an empty SBD-3 without protection went 5669lbs.
as a "scout" with no bomb and 180 US gallons of fuel and W/O protection fuel it went 7784lbs.

Armament was 227lbs
Equipement was 318lbs
however
protection for the oil tank went ..........................30lbs
protection for the center section fuel tanks 232lbs
protection for the outer wing fuel tanks ......218lbs'
Armor and B/P glass..............................................212lbs

An SBD-3 "scout" with protection and 150US gallons of fuel went 8289lbs.

If you filled the outer tanks it would hold 260 gallons but weight went to 8986lbs.

All figures are from the manual.

The Dauntless was an excellent dive bomber and a very good recon plane. As a fighter it left more than one thing to be desired and no minor amount of fiddling was going to turn it into even a passable fighter in 1942.
 
For a dedicated dive-bomber/scout born in the 1930's, the SBD performed in it's role above and beyond expectation.
To think that fiddling around with it's design in order to make a fighter out of it almost sounds like the Luftwaffe leadership wanting every single aircraft submitted for their approval to perform a multitude of tasks outside of it's design perimeters - which in turn consumed considerable time, effort and money for very little gain.
While the SBD was being designed and built (as a scouting dive-bomber), there were quite a few dedicated fighters also being designed and developed. Trying to create a fighter out of the SBD would divert much needed time, designers, developers and shop space that could otherwise be used for more important tasks.

Let the SBD do what it was designed to do and leave the dedicated fighters to do what they do...
 
The SBD was used as a "fighter" to counter dive and torpedo bombers, scout aircraft, and possibly maritime patrol aircraft; like a number of attack aircraft, it was maneuverable when lightly loaded. It also had enough performance, armament, and good enough handling to deal with unescorted attack aircraft. Turning it into a fighter could best be done by putting the drawings through a shredder and starting from new sheets of vellum. Douglas did a great job with the SBD; they may not have done so well with a fighter.
 
Interesting proposition. I wonder whether we could explore it a little deeper, as I'm less familiar with the capabilities of these other, more land-deployed, dive bombers. I think I can add this much. These SBDs were bombing moving targets, that, the whole time, were shooting back at them, while trying desperately to evade them. That was no picnic. What's more, the targets were rocking and rolling, literally, up and down, from side to side, and bow to stern, while the pilots were making adjustments for that in their dives. Give these SBDs a bridge, or a runway, or a dam, and it's like a gift, no? So what's the big deal, just their load-capabilities? Let's dissect this proposition, see where we end up on it.
 
Ive read the army used its A24s in much more shallow angle dives making them much less accurate. So it was the way in which they were used not any inherent qualities of the plane itself that made it less effective for the army.
 
Peter Gunn said:
I always attributed the SBD's success to the excellent training and dedication of the Navy dive bomber pilots.
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Both. The machine was an easy flyer, from what I've always understood. It was just designed that way, and well-behaved. Most of the pilots that flew it, from what I've been told, loved it.
 

All of those missions are different.
Heavy bombers couldn't hit ships at sea.
Medium bombers could skip bomb but that technique wasn't developed until later, plus I don't know how well that would work against a carrier, cruiser or battleship with their more extensive AA batteries.
Medium bombers couldn't bomb factories deep inside Germany either.
Dive bombers could hit any pin point target, whether it was a ship, bunker, bridge, etc, but it didn't work against Germany because their AA was very good. Medium bombers were forced up to much higher altitudes in Europe due to German AA while against Japan, low level attacks by medium and even heavy bombers worked well. Unescorted, self defending bombers also worked against Japan, of course they didn't do well against Germany.

Just like a Jeep, truck or tank were designed for a job and neither will replace the other for its intended role. You wouldn't haul supplies long distance with a tank and you wouldn't assault a defended position with a truck.

A dive bomber, medium bomber and heavy bomber each have their intended job and limitations and none will do the job the others were designed specifically to do.
 
Before guided weapons, there were exactly two ways for aircraft effectively to attack ships at sea: dive bombers and torpedo bombers. The USN seemed to have deprecated the latter -- USS Ranger didn't even have a torpedo magazine and USN aircraft torpedoes that were problematic.
 

Lets remember where this little detour started. I wrote: "Well the T-6 had / has a 600 hp engine (and managed 200 mph with that), the SBD like the F4F had a 1,200 hp engine, so with double the horsepower I think they would actually be closer to competitive. The T-6 is also a two-seater whereas the hypothetical SBD fighter would be a single-seat aircraft." Then Milflyer mentioned that the Boomerang was basically a T-6 (or NA-16) with an R-1820 and it wasn't so great. I agreed, but pointed out that the performance would be about the same as the theoretical "SBF Flauntless", the main problem with the Boomerang being that just came out too late, in April 1943. In 1941 or 1942 a carrier fighter with similar performance would be theoretically more effective.

And then you predictably started making all your assertions that it was impossible. The truth is it's just speculation so the best any of us can do is an educated guess.


To make the Boomerang the Aussies removed the rear seat and shaved off a little bit of wing space, and doubled the takeoff HP of the engine from 600 to 1200 hp. (Using takeoff HP here as shorthand rather than going through the HP at every altitude from Sea Level to Ceiling). To make the SBF, I was just proposing taking out gear to reduce weight:
  • Rear seat and rear cockpit.
  • Extra radio
  • The extra set of flight controls for the gunner
  • Armor for gunner
  • Two .30 cal guns with their ammunition
  • The great big dive brakes
  • The bomb cradle for the dive bomb
I don't know how much all this stuff weighs but I can make an educated guess. Most of the weight saving I would assume would come from the dive brakes and the gunners station with guns etc., the bomb cradle would help with drag. In addition they could have shortened the wings slightly as they did for the Boomerang, and possibly install a Pratt & Whitney R-1830 of the Wildcat instead of the Wright 1820, maybe tighten the cowling slightly to reduce drag and tune the exhaust for better "push", and cover up a few gaps like adding wheel covers.

The boomerang was 5,373 lbs empty, vs. the SBD at 6,400 lbs empty. They also cut the wings down from a 42' span on the T-6 and NA-16 to 36' on the Boomerang.

My theory again (to be clear) was that if you could reduced say ~800 to 1,000 lbs weight for the hypothetical "SBF", since the dimensions would be the roughly the same as the Boomerang and the weight would be just about the same with the same engine, power / mass would be equivalent and you would probably get a ~300 mph fighter which would be suitable as a stop-gap "Scout Fighter" airplane for the early war years, which could have served as a scout and emergency fighter but still retain some bombing ability.

The only real questions as to whether the above scenario would be possible are 1) how much weight could you actually take out of an SBD to make it into a single-seat "scout fighter", and 2) how much of the speed difference between and SBD and say, a Buffalo or a Wildcat is due to drag as opposed to weight. Also how efficient (in terms of drag vs. lift) was the SBD wing in general compared to the NA-16 wing since they did have a quite different wing shape.

As for all the fuel weights quoted, you would still probably want to retain the full fuel capacity for longer range scouting missions, but of course, in a CAP situation the fuel would be reduced, either because you sent it up that way or because it was doing CAP after returning from a raid.

I don't know exact figures for drag coefficient but probably like a lot of people here, I have accurate scale models of several of the primary combat aircraft of the Pacific Theater. You can eyeball them and clearly see that the F2A and TBF are by far the 'thickest' in the fuselage. The Ki-43 is the thinnest followed by the A6M. The SBD is similar to the F4F but slightly thinner in horizontal profile. You can see it here:


SBD top / left F4F bottom / right.

So I guess the biggest question for me as to viability of the idea would be how much do the dive brakes weigh. That would get us a lot closer to a realistic number for the weight reduction since we can probably figure out how much the gunners armor, guns ammo and other gear weighed.

In terms of the bigger picture, without the dive bombing ability it would certainly not be as deadly as an SBD, which would really be the reason not to do it, since the SBD was more valuable due to it's lethality against ships. The "SBF" might have a small niche for example for escort carriers, as a longer ranged alternative to the F4F with a little bit better strike capability.
 
michael rauls said:
Ive read the army used its A24s in much more shallow angle dives making them much less accurate. So it was the way in which they were used not any inherent qualities of the plane itself that made it less effective for the army.
Click to expand...

Yes, from what I understand this was the issue - it was also a problem with the early Marine Corps piloted SBD's, they did the "shallow dive" attacks as opposed to proper dive-bombing runs (which required extra training) and they suffered higher attrition and lower accuracy in their early strikes. From what I gather the A-24 was more effective both in terms of accuracy and survivability when they used as an actual dive-bomber. This was also the A-24B with a bigger engine.

However I think Greg does make a good point about Naval vs. ground targets. In a Naval battle like Midway you could afford to lose a lot of planes especially against naval targets. Less so against ground targets like when the Japanese bombed the Midway airfields. If you trade 20 aircraft for an aircraft carrier or a battleship that is an acceptable loss rate. If you lose the same 20 to put a few craters in an island airfield which can be bulldozed back into shape in two days, or even worse, to take out one tank or a couple of mortars, it's a bad trade.

Using dive bombers as tactical weapons in land combat was a different game so to speak but the Germans were able to do it with success with their Ju 87 in Russia and in the Med well into the middle of the war. From reading about the Mediterranean campaigns the A-36 (P-51A in dive bomber configuration) was a fairly important strike aircraft in Italy for the Allies.

Generally speaking by the later war, fighter bombers were preferred for tactical bombing over any kind of pure bomber type because their greater speed and ability to tangle with enemy fighters made them more survivable. For that reason the Germans switched a lot of their Stuka units over to Fw 190F etc., and the Americans switched from using light bombers of any kind over more to Corsairs and Hellcats, and Kittyhawks* in the Pacific, and to P-47s in the Med and later Europe. The other main reason though is that while early war dive bomber designs were successful, attempts to upgrade the dive bomber, basically to make a faster version, mostly failed. So the fighter had to do the job.

The advantage of the dive bomber over the fighter bomber is accuracy. A higher hit rate means less sorties and that too translates to lower attrition. If you are getting a 3% per sortie hit rate against tanks, gun emplacements or bridges with fighter bombers, and an 8% rate with dive bombers, that means less missions sent to the same target to get the job done. That has to be factored into the loss and casualty per sortie rates.


The roles we think are pegged to different types of aircraft were not always so hard and fast. In the Med, the B-24 heavy and B-25, A-20 and B-26 light / medium bombers were actually quite successful attacking as level bombers in taking out Axis airfields, (and forcing air to air combat with the German and Italian fighter units on Allied terms). This is the main way that Axis air power was broken in Tunisia and later Sicily and Sardinia etc.

Medium bombers in the skip-bombing role enhanced their surviveability through flak suppression, the method they worked out being if you have say 12 x B-25s with a eight to a dozen nose guns each plus a few with 75mm cannon they can suppress the flak sufficiently to hit with their skip-bombs. That seemed to work in the Pacific and to a lesser extent in the Med, though the latter victories I think were mostly against transport ships and Italian naval vessels, whereas the German military targets were much more heavily defended.




* they still made heavy use of SBDs, Helldivers and TBF / TBN especially for naval targets and ASW, but against ground targets especially more heavily defended ones, fighters were better. I know A-24, Helldivers and TBF were used against ground targets but their attrition was higher. The other exception in the European land war was the dedicated, heavy ground attack aircraft like the Il2 Sturmovik, Hurricane IID, Ju 87G and the HS 129. Only the Russians really made this work on a large scale though and only at great cost in casualties.
 
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Regarding the flaws of the SBD and speed being high among them per the "slow but deadly" nickname, a lot of times what pilots were apparently thinking of as speed was the cruise speed. I read a lot of interviews with WW2 pilots in the Med and they often focus on things that modern enthusiasts don't think about nearly as much - takeoff characteristics, cockpit comfort, functionality of the radio and cruise speed are probably the big four. Another big one is reliability of the guns since guns jamming was a major problem especially in the early war but really right to the end.

Regarding speed, sometimes a plane that can go fast in theory is still cruising at very slow speed, especially if it has an external bomb load. Cruise speed for the SBD was listed as 150 mph / 240 kph, while top speed was a much higher 250 mph / 400 kph but only a certain altitude and without external stores.

Trundling along at 150 mph makes you very vulnerable to high performance fighters. It's hard to evade, it's hard to disengage, hard to fight back. Acceleration to combat speed can take a while. It also makes the flight a lot longer in terms of time.

An aircraft with a bit higher standard cruising speed / per military SOP is a lot more capable of surviving combat. This was the issue in the Med with the Blenheim, it had a cruising speed of around 100 mph. The Martin Baltimore, which the RAF had in some numbers, cruised at 224 mph which made it much more survivable, thus the RAF switched over to those (and to A-20s and a few others) for bombers, as well as to fighter bombers in lieux of the Blenheims. Kittyhawks cruised at about 200 - 250 mph depending on the type, Hurricanes around 240 mph depending on the type. Obviously both had a better chance to survive being bounced than a Blenheim.

A6M cruised about 230 mph
Ki-43 cruised at 220 - 270 mph depending on the type
D3A cruised about 180 mph
B5N cruised at 169 mph
G4M "Betty" cruised at 196 mph
TBF cruised at 153 mph
F4F cruised at 155 mph
F6F cruised at 200 mph
F4U Corsairs cruised about 215 mph
P-47 I've seen anywhere from 231 mph (P-47C) to an astonishing 350 mph (P-47N, presumably at high altitude)
P-38 cruised at 275 mph
A-20 cruised at 230 to 300 mph depending on the type (and load I'm sure)
B-25 cruised at 230 mph
B-26 cruised at 215 - 260 mph depending on the type (I assume short wing vs. longer wing)

Anyway my point is that cruising speed is one of those lesser known stats which could make a difference in a given aircraft's performance and attrition rate particularly as a bomber. SBD seems to have done Ok in spite of a slow cruising speed but it was certainly noticed by it's pilots. Obviously I know those speeds would vary depending on load and how far they were planning to fly, these are just what is listed in some books I have as I assume, military standard.
 

The range cruise for the IJN aircraft listed is too high. Most IJN aircraft were designed for low speed cruise to achieve very long endurance and range.

A6M5 range cruise was 146 mph at 1500ft to acheive 1800 miles (A6M2 was similar) and at Guadalcanal the A6Ms were cruising at these speeds during their ~1200 mile flights. Ki-43 was very similar. Higher speed cruise could be used on shorter range missions.

D3A2 range cruise was 125 - 167mph at 1500ft

B5N2 range cruise was 113 to 146mph at 1500ft

G4M range cruise was as low as 114mph.



(Data from TAIC Manual no.1 which was a US Intelligence summary of IJ aircraft based upon captured flight manuals.)
 
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