SBD dive bombing procedures

[Retattack]

Does anyone have the specific dive procedures followed by Dauntless pilots in the beginning of the war (Coral Sea and Midway)? I'm particularly interested in release height, target airspeed and dive angle, and whether the sight had a fixed depression or was adjustable, and what the assumptions were for the sight.

Are there any training manuals, ballistics tables or the like?

(I'm trying to make sense of various accounts of Midway, and having a hard time reconciling them . . . first time poster, apologies for inadvertent gaffes.)

 

[Escuadrilla Azul]

R Retattack wellcome to the forum!

Somebody will drop by and will leave a great answer

 

[EwenS]

There is a lengthy description with diagrams in Peter C Smith's book "Douglas SBD Dauntless" published by Crowood. Chapter Seven "The SBD Battle Scenario". It covers the whle operation from scouting to find the enemy through to withdrawal after the drop. Major points to answer most of your questions.:-

1. Typical cruise height to target - 14-16,000ft
2. Sub-sections stacked en echelon below one another giving all a clear view of target (weather permitting)
3. Visual contact with target 25-40 miles
4. Descent to 10-12,000ft assuming line astern of sections (or aircraft in sections), opening out to 500yd spacing to mitigate effects of AA, and aiming to cross the path of the target.
5. Optimum angle of attack was 70 degrees or just over (70-75 was the norm for SBD squadrons in the Pacific war)
6. Sight used in early war period was the 3x telescopic fixed to the aircraft. Not used until near the end of the dive (there was a problem with the sight and windscreen fogging during rapid descents until special coatings became available). "Considered an aid to dive bombing not a panacea". Only in 1943 was a Reflector Sight fitted to the aircraft.
7. Aircraft begins pull out at 2,900ft (3,000 ft slant range to target)
8. Bomb release at 2,500ft, Bombing Angle 6 degrees (slant range to target 2,650ft).
9. Pull out and escape at 1,500ft
10. Engine "kept revving over just enough to make sure of an instant response when called for".

Preferred direction of attack was downwind out of the sun. The pilot had to account for wind deflection and drift when aiming as well as target movement.

No speeds are mentioned in this chapter.

I hope that this helps.

 

[Retattack]

R Retattack wellcome to the forum!

Thanks! Looking forward to any illumination.

To expand a bit: I'm a recently retired former attack guy (A-4/AV-8) who suddenly has plenty of time to catch up on my guilty pleasure of WWII historical reading. Thumbing through Shattered Sword, I saw several apparently widely accepted revisions to the familiar Midway narrative. But some of the specifics seem to me questionable, or at least not what I'd assumed, and some of it is in the most critical part of the battle.

For example, the description of the attack on Akagi has two claims I find hard to credit: 1) Best's section bombed in close formation; 2) we know who dropped the bomb that scored the fatal hit. On the first point, I've never even heard of anybody dive bombing in formation, and Best's after action says "The first section of the first division joined up immediately after pull-out from the dive." Which implies they'd separated. On the second point, the rationale from Shattered Sword was his backseater's quote "Nobody pushed his dive steeper or held it longer than Dick." In fact, in standard dive-bombing, a steep fast dive held to lower than planned altitude will always result in a long hit, and many duds.

However, it is possible for this to be a correct description. There are modern gunsights that rely on angle change to the target (e.g., ARBS), and with enough practice, and a relatively slow and low delivery, the human eyeball could probably come up with a comparable solution. In that case, there is no hard release altitude, you just have to pull out in time to avoid ground impact, and hope the bomb has time to arm. On that point, there are also contemporary reports of armorers spinning bomb fuze vanes prior to loading (to reduce bomb arming times). And while all this strikes me as ridiculously nonstandard and dangerous (especially loading partially armed bombs on carrier aircraft), there may have been various cowboy solutions to a procedures vacuum.

Anyway, I'm stuck with two incompatible interpretations, and I'd love any input on which was correct.

 

[Retattack]

Sight used in early war period was the 3x telescopic fixed to the aircraft. Not used until near the end of the dive (there was a problem with the sight and windscreen fogging during rapid descents until special coatings became available). "Considered an aid to dive bombing not a panacea". Only in 1943 was a Reflector Sight fitted to the aircraft.

Thanks for the reply. And thanks for the reference, I'll get it. (I've got an expanded USN training video CD coming from Zeno's too, but if it's anything like the short version on Youtube, it's going to be too generic to be much help.)

I've been unable to find anything useful on the sight. I've seen claims it was designed for a 70 degree dive, but nothing about whether it had a fixed depression for a standard delivery, adjustable, or was just boresighted to the aircraft (presumably with depression rings). But that "aid to dive bombing" bit suggests it was in fact an exercise in eyeballing and not (what I consider standard for manual dive bombing) hitting a preplanned dive angle, airspeed and release height with a predetermined trajectory drop calculated and set on the sight.

 

[Thumpalumpacus]

Thanks! Looking forward to any illumination.

To expand a bit: I'm a recently retired former attack guy (A-4/AV-8) who suddenly has plenty of time to catch up on my guilty pleasure of WWII historical reading. Thumbing through Shattered Sword, I saw several apparently widely accepted revisions to the familiar Midway narrative. But some of the specifics seem to me questionable, or at least not what I'd assumed, and some of it is in the most critical part of the battle.

For example, the description of the attack on Akagi has two claims I find hard to credit: 1) Best's section bombed in close formation; 2) we know who dropped the bomb that scored the fatal hit. On the first point, I've never even heard of anybody dive bombing in formation, and Best's after action says "The first section of the first division joined up immediately after pull-out from the dive." Which implies they'd separated. On the second point, the rationale from Shattered Sword was his backseater's quote "Nobody pushed his dive steeper or held it longer than Dick." In fact, in standard dive-bombing, a steep fast dive held to lower than planned altitude will always result in a long hit, and many duds.

However, it is possible for this to be a correct description. There are modern gunsights that rely on angle change to the target (e.g., ARBS), and with enough practice, and a relatively slow and low delivery, the human eyeball could probably come up with a comparable solution. In that case, there is no hard release altitude, you just have to pull out in time to avoid ground impact, and hope the bomb has time to arm. On that point, there are also contemporary reports of armorers spinning bomb fuze vanes prior to loading (to reduce bomb arming times). And while all this strikes me as ridiculously nonstandard and dangerous (especially loading partially armed bombs on carrier aircraft), there may have been various cowboy solutions to a procedures vacuum.

Anyway, I'm stuck with two incompatible interpretations, and I'd love any input on which was correct.

When Best realized that Akagi was getting two squadrons and Kaga none, he tried to swing his squadron to Kaga, but only his two wingmen aborted their dives and formed on him for the short trip to Kaga. Due to the last-minute nature of the decision, they didn't have time to get into line-ahead, nor to line up per doctrine (along the length of the ship, downwind, and so on), so they bombed from abeam in a loose V formation, with Best in the middle.

The only bomb that landed aboard Kaga landed abreast the bridge. One near-miss went over the port bow, and one near-miss struck the water near the starboard stern. By elimination, we see that Best's bomb had to be the hit.

 

[special ed]

The USN museum has many static exhibits and with your history of A-4 & AV-8 you may get a close up of the sight in the SBD-3 on display. I believe it was the training airplane recovered from Lake Michigan which was an actual combat veteran. It was supposed to be restored just as it was in combat.

 

[Retattack]

The USN museum has many static exhibits and with your history of A-4 & AV-8 you may get a close up of the sight in the SBD-3 on display. I believe it was the training airplane recovered from Lake Michigan which was an actual combat veteran. It was supposed to be restored just as it was in combat.

Genius! Just checked and Pensacola has an SBD-2 from the actual battle . . . and we just happen to have a reunion scheduled there for November. I think I can profitably shelve this burning curiosity for a few months, especially since I'll have the company of a couple dozen like-minded mud movers who ought to be interested in the early days of dive bombing. (I feel stupid, but that's not new.) Thanks a ton!

 

[ThomasP]

re

There is a lengthy description with diagrams in Peter C Smith's book "Douglas SBD Dauntless" published by Crowood. Chapter Seven "The SBD Battle Scenario". It covers the whle operation from scouting to find the enemy through to withdrawal after the drop. Major points to answer most of your questions.:-

1. Typical cruise height to target - 14-16,000ft
2. Sub-sections stacked en echelon below one another giving all a clear view of target (weather permitting)
3. Visual contact with target 25-40 miles
4. Descent to 10-12,000ft assuming line astern of sections (or aircraft in sections), opening out to 500yd spacing to mitigate effects of AA, and aiming to cross the path of the target.
5. Optimum angle of attack was 70 degrees or just over (70-75 was the norm for SBD squadrons in the Pacific war)
6. Sight used in early war period was the 3x telescopic fixed to the aircraft. Not used until near the end of the dive (there was a problem with the sight and windscreen fogging during rapid descents until special coatings became available). "Considered an aid to dive bombing not a panacea". Only in 1943 was a Reflector Sight fitted to the aircraft.
7. Aircraft begins pull out at 2,900ft (3,000 ft slant range to target)
8. Bomb release at 2,500ft, Bombing Angle 6 degrees (slant range to target 2,650ft).
9. Pull out and escape at 1,500ft
10. Engine "kept revving over just enough to make sure of an instant response when called for".

Preferred direction of attack was downwind out of the sun. The pilot had to account for wind deflection and drift when aiming as well as target movement.

No speeds are mentioned in this chapter.

My bold added to the above quote.

I believe the steady dive speed of the SBD under the conditions indicated in EwanS's post above would be ~240 knots. If this is the case and we assume that the pullout is started from 1g in a ~70° dive angle at ~3,000 ft AGL, then this would result in a maximum of 5g at the bottom of the pullout at ~1,500 ft AGL (I think - if I have done my math right).

I used 240 knots (405 ft/sec) TAS for the SBD's steady dive speed as I ran across it in a quote from Best (he did not say whether it was TAS or IAS but at 1,500-3,000 ft there is not much difference), and from among my other notes (no particular reference noted) that say 240-270 knots in a steady dive with dive brakes deployed..

I used a 5g maximum in my calculations due to running across material in the past that said USN dive bomber pilot were supposed to avoid more than 5g pullout forces due to the probability of blacking out. In reality many pilots would begin to grey out at ~3g sustained, which would be the ~average g force under the above conditions.

 

[PStickney]

There is a lengthy description with diagrams in Peter C Smith's book "Douglas SBD Dauntless" published by Crowood. Chapter Seven "The SBD Battle Scenario". It covers the whle operation from scouting to find the enemy through to withdrawal after the drop. Major points to answer most of your questions.:-

1. Typical cruise height to target - 14-16,000ft
2. Sub-sections stacked en echelon below one another giving all a clear view of target (weather permitting)
3. Visual contact with target 25-40 miles
4. Descent to 10-12,000ft assuming line astern of sections (or aircraft in sections), opening out to 500yd spacing to mitigate effects of AA, and aiming to cross the path of the target.
5. Optimum angle of attack was 70 degrees or just over (70-75 was the norm for SBD squadrons in the Pacific war)
6. Sight used in early war period was the 3x telescopic fixed to the aircraft. Not used until near the end of the dive (there was a problem with the sight and windscreen fogging during rapid descents until special coatings became available). "Considered an aid to dive bombing not a panacea". Only in 1943 was a Reflector Sight fitted to the aircraft.
7. Aircraft begins pull out at 2,900ft (3,000 ft slant range to target)
8. Bomb release at 2,500ft, Bombing Angle 6 degrees (slant range to target 2,650ft).
9. Pull out and escape at 1,500ft
10. Engine "kept revving over just enough to make sure of an instant response when called for".

Preferred direction of attack was downwind out of the sun. The pilot had to account for wind deflection and drift when aiming as well as target movement.

No speeds are mentioned in this chapter.

I hope that this helps.

Just a couple of minor additions - from one of Eric Brown's Flight Test Reports.
The dive brakes were effective, but slow moving - so the procedure was to hit the flap lever as you started to roll in. Otherwise, the SBD would accerate more than was prudent. The dive brakes were very effective - they'd hold the airplane to 240 kts in the dive. Due to the slow retraction, the pilot would generally retract the flaps on bomb release, and start the pullout as they retracted.

 

[PStickney]

Thanks! Looking forward to any illumination.

To expand a bit: I'm a recently retired former attack guy (A-4/AV-8) who suddenly has plenty of time to catch up on my guilty pleasure of WWII historical reading. Thumbing through Shattered Sword, I saw several apparently widely accepted revisions to the familiar Midway narrative. But some of the specifics seem to me questionable, or at least not what I'd assumed, and some of it is in the most critical part of the battle.

For example, the description of the attack on Akagi has two claims I find hard to credit: 1) Best's section bombed in close formation; 2) we know who dropped the bomb that scored the fatal hit. On the first point, I've never even heard of anybody dive bombing in formation, and Best's after action says "The first section of the first division joined up immediately after pull-out from the dive." Which implies they'd separated. On the second point, the rationale from Shattered Sword was his backseater's quote "Nobody pushed his dive steeper or held it longer than Dick." In fact, in standard dive-bombing, a steep fast dive held to lower than planned altitude will always result in a long hit, and many duds.

However, it is possible for this to be a correct description. There are modern gunsights that rely on angle change to the target (e.g., ARBS), and with enough practice, and a relatively slow and low delivery, the human eyeball could probably come up with a comparable solution. In that case, there is no hard release altitude, you just have to pull out in time to avoid ground impact, and hope the bomb has time to arm. On that point, there are also contemporary reports of armorers spinning bomb fuze vanes prior to loading (to reduce bomb arming times). And while all this strikes me as ridiculously nonstandard and dangerous (especially loading partially armed bombs on carrier aircraft), there may have been various cowboy solutions to a procedures vacuum.

Anyway, I'm stuck with two incompatible interpretations, and I'd love any input on which was correct.

The telescopic sight was boresighted along the aircraft centerline. It had a non-adjustable crosshair reticle, and a slip/skip ball like a Turnn & Bank Indicator to give the pilot an indication of whether he was in coordinated flight. The later reflector sights were the same - so the pilots were using TLAR (That Looks About Right) computing. Dive Angles were at least 70 degrees - often more, so long bombs weren't very long.
Not a Jet Attack Guy, but it's always looked to me that you guys were bombing from somewhere around 45 degrees, and about twice as fast (or more) so a depressed sight is real important, and ARBS is Real Important. (There were World War 2 ARBS systems for SBDs and SB2Cs - precursors to the later DIve/Toss systems of the '60s. Don't know if they actually got used) - and a long bomb is going to be a lot longer.

 

[Retattack]

The telescopic sight was boresighted along the aircraft centerline. It had a non-adjustable crosshair reticle, and a slip/skip ball like a Turnn & Bank Indicator to give the pilot an indication of whether he was in coordinated flight. The later reflector sights were the same - so the pilots were using TLAR (That Looks About Right) computing. Dive Angles were at least 70 degrees - often more, so long bombs weren't very long.
Not a Jet Attack Guy, but it's always looked to me that you guys were bombing from somewhere around 45 degrees, and about twice as fast (or more) so a depressed sight is real important, and ARBS is Real Important. (There were World War 2 ARBS systems for SBDs and SB2Cs - precursors to the later DIve/Toss systems of the '60s. Don't know if they actually got used) - and a long bomb is going to be a lot longer.

Thanks, that's about 90% of what I'm looking for. I'm still waiting on my training film, but it seems to me they have to have a set of criteria for bomb release height (to ensure proper arming, if nothing else). I got the SBD "Pilot's Handbook," and it has charts for terminal velocity dives that show a nose down AOA of about 4.8 degrees for a standard 70 degree 240 KIAS delivery, so a boresighted reticle would have about an 85 mil trajectory drop built in. That would seem to be in the ballpark.

We had data for lots of deliveries, from laydown to 60 degree dives. We generally did laydown for napalm and some special weapons, 10 deg/450K popups, and 30 deg/ 450-500K for practice. But real world was practically always 45 deg/500K with a 5000'+ release. And yes, the slant range is such that a long (or short) bomb will be grossly off target. Obviously a steeper dive removes a lot of the error sensitivity (in the extreme: a 90 degree dive has zero error due to release height), and a lower airspeed allows for much shorter slant range, and correcting on the fly for wind or a moving target is more of a TLAR problem than a ballistics one. So I can see how that might be a reasonable approach, with some constraints.

We had a set of bombing manuals: a classified tactics manual, and an unclassified ballistics manual (with trajectory drop, slant range, time of fall, and error sensitivities for every piece of ordnance and every plausible release). I wouldn't expect quite the level of detail in 1942, but it seems to me they had to have something that covered at least the limits of the basic bombs (esp 500# and 1000#), fuzes, and standard deliveries. The Pilot's Handbook reads like a very short NATOPS manual, and I just assumed there was something similar out there for tactical training, but so far haven't been able to find anything.

 

[PStickney]

Thanks, that's about 90% of what I'm looking for. I'm still waiting on my training film, but it seems to me they have to have a set of criteria for bomb release height (to ensure proper arming, if nothing else). I got the SBD "Pilot's Handbook," and it has charts for terminal velocity dives that show a nose down AOA of about 4.8 degrees for a standard 70 degree 240 KIAS delivery, so a boresighted reticle would have about an 85 mil trajectory drop built in. That would seem to be in the ballpark.

We had data for lots of deliveries, from laydown to 60 degree dives. We generally did laydown for napalm and some special weapons, 10 deg/450K popups, and 30 deg/ 450-500K for practice. But real world was practically always 45 deg/500K with a 5000'+ release. And yes, the slant range is such that a long (or short) bomb will be grossly off target. Obviously a steeper dive removes a lot of the error sensitivity (in the extreme: a 90 degree dive has zero error due to release height), and a lower airspeed allows for much shorter slant range, and correcting on the fly for wind or a moving target is more of a TLAR problem than a ballistics one. So I can see how that might be a reasonable approach, with some constraints.

We had a set of bombing manuals: a classified tactics manual, and an unclassified ballistics manual (with trajectory drop, slant range, time of fall, and error sensitivities for every piece of ordnance and every plausible release). I wouldn't expect quite the level of detail in 1942, but it seems to me they had to have something that covered at least the limits of the basic bombs (esp 500# and 1000#), fuzes, and standard deliveries. The Pilot's Handbook reads like a very short NATOPS manual, and I just assumed there was something similar out there for tactical training, but so far haven't been able to find anything.

As I understand it, if the tactical situation allowed (As in not having to shoot Zeros off your tail), the Radio Operator/Gunner would rotate his seat forward and call off altitudes in the dive -
Not unlike the WSO/NFO in the F-4. According to the manuals in my collection, the Gunner's cockpit had its own instruments (Airspeed, Altimeter, Compass and Clock), and a stick, rudder and throttle (But not mixure and prop).

 

[Retattack]

As I understand it, if the tactical situation allowed (As in not having to shoot Zeros off your tail), the Radio Operator/Gunner would rotate his seat forward and call off altitudes in the dive -
Not unlike the WSO/NFO in the F-4. According to the manuals in my collection, the Gunner's cockpit had its own instruments (Airspeed, Altimeter, Compass and Clock), and a stick, rudder and throttle (But not mixure and prop).

Yes, the Pilot's Handbook has good pictures of the rear instrument panel and controls (interestingly, the stick is removable, and in one picture it's in the "stowed position" on the side of the cockpit). I read somewhere that a Zero couldn't chase an SBD in the actual dive (I thought it was in Dusty Kleiss's book, but if so, I can't find it again). If that's right, I'd expect the usual SOP was to face forward.

 

[yosimitesam]

The telescopic sight was boresighted along the aircraft centerline. It had a non-adjustable crosshair reticle, and a slip/skip ball like a Turnn & Bank Indicator to give the pilot an indication of whether he was in coordinated flight. The later reflector sights were the same - so the pilots were using TLAR (That Looks About Right) computing. Dive Angles were at least 70 degrees - often more, so long bombs weren't very long.
Not a Jet Attack Guy, but it's always looked to me that you guys were bombing from somewhere around 45 degrees, and about twice as fast (or more) so a depressed sight is real important, and ARBS is Real Important. (There were World War 2 ARBS systems for SBDs and SB2Cs - precursors to the later DIve/Toss systems of the '60s. Don't know if they actually got used) - and a long bomb is going to be a lot longer.

"There were World War 2 ARBS systems for SBDs and SB2Cs - precursors to the later DIve/Toss systems of the '60s. Don't know if they actually got used."

Probably not used, but here's one: ASG-10 Toss bombing device

 

[Retattack]

Just got my training video in the mail (props to Zeno's), and looking it over, most of what we'd guessed appears to be correct. Caveat: the video referenced is part one and it refers to more advanced follow-on films, though so far I've been unable to find any. Short intro version is available at archive.org (here) . . . but it's missing the important parts.

The sight is boresighted (it doesn't say if there is any depression angle, but it is below the "line of flight" [velocity vector]) and apparently doesn't even have mil rings, as it describes using ground references for scaling corrections. Standard delivery appears to be 70 degrees (it says 65-70 in a few places), and had standard stuff about correcting dive angles where feasible. All other corrections were "Kentucky windage" type, and the sight accounted for the correct trajectory drop assuming the correct dive angle and release height. It doesn't mention airspeed, which I presume to mean they assumed terminal velocity or it was standard and discussed elsewhere.

I'm going to continue to look for the more advanced stuff, but I'm confident enough now to make a conclusion about what I read in Shattered Sword:

Thus, the first and third bombs were misses, with the third landing very close aboard indeed. It was the second bomb, landing at the aft edge of the middle elevator, which doomed Akagi. This weapon was almost unquestionably aimed by Best himself. He was a noted dive-bomber pilot and had a reputation for both boldness and consummate skill. In the words of his backseater, Aviation Chief Radioman James F. Murray, "Nobody pushed his dive steeper or held it longer than Dick."44 Given the "V" formation Best's element dived in, it is almost inconceivable that the trajectories of the bombs could have crossed in midair. Furthermore, from what we know about how the bombs landed in relation to the ship and each other, that is, in a rough "V" pattern themselves, it is likewise almost a certainty that the center plane in the "V" dropped the bomb that hit dead center on Akagi. That plane was piloted by Lieutenant Best.

The middle of this description is simply wrong. The backseater (Murray) describes a popular, but faulty, view of dive bombing that doesn't result in more accuracy or hit probability. Also, if the three were in close formation (which I doubt), the wingmen weren't aiming at all, just looking at lead, and the first bomb has to be Best's unless he's calling releases over the radio (which nobody reports). The alternative, which I suspect is more likely, is that the three aircraft are in close proximity but with sufficient distance for each to aim separately. This also corresponds with Best's after action report. In that case it is impossible to determine which bomb was whose (and it certainly is possible for the guy who dropped the bomb on the left to impact on the center, or right--and the lead's bomb can land second, or third, though that's slightly less likely). Not sure if any of this matters--certainly doesn't detract from the bravery of the men involved--but it makes me question other aspects of the otherwise overwhelmingly impressive book. There may be other data the authors omitted that support their conclusion, but my impression is it may be an attempt to nail down an inherently uncertain detail in the middle of a very confused battle.

 

[Thumpalumpacus]

This also corresponds with Best's after action report. In that case it is impossible to determine which bomb was whose (and it certainly is possible for the guy who dropped the bomb on the left to impact on the center, or right--and the lead's bomb can land second, or third, though that's slightly less likely).

Your conclusion doesn't follow. We know that Best was in the middle, according to Parshall and Tully, who cite Mark Horan. From the first paperback edition of Shattered Sword:

 

[SaparotRob]

Your conclusion doesn't follow. We know that Best was in the middle, according to Parshall and Tully, who site Mark Horan. From the first paperback edition of Shattered Sword:

View attachment 766026

I hope your copy is in better shape than mine is.

 

[Retattack]

Your conclusion doesn't follow. We know that Best was in the middle, according to Parshall and Tully, who site Mark Horan. From the first paperback edition of Shattered Sword:

You appear to believe that with a loose formation of diving aircraft, the bomb impacts must mirror their location in the formation. That isn't true.

 

[Thumpalumpacus]

You appear to believe that with a loose formation of diving aircraft, the bomb impacts must mirror their location in the formation. That isn't true.

Not exactly. The central hit and the two near-misses were about 300 or so foot from each other to either side lengthwise, and also separated abeam -- the bow near-miss over, the central hit, and the stern near-miss an undershot.

Given the low release altitude, I doubt there's so much windage that Best's bomb and either of his wingmen's crossed paths to that extent, unless they were themselves flying different dive courses. But they were all coming in from starboard abeam, if I remember rightly. What are the odds that their dives are that divergent, that bombs go both long, short, and askew?

It's an Occam's Razor thing. Of course, I'm no pilot, so your apparent disagreement, informed by your personal experience, is one more datum for me to take into account. Thanks for speaking it.