SBD dive bombing procedures

[R Leonard]

The USN flirted with an automatic recovery system in the 1930's. The aviators hated the concept and did not trust it, preferring Mk I human control, so the concept was discarded.

 

[SaparotRob]

Bit of a hijack.
Is dive bombing a lost art for modern (large) air forces? Has that role been totally superseded by modern munitions?

 

[GrauGeist]

Bit of a hijack.
Is dive bombing a lost art for modern (large) air forces? Has that role been totally superseded by modern munitions?

Dive bombing is no longer nessecary to put munitions on a specific target, so I suppose it could be considered a lost art.

In this modern age, about the closest you'll get to a dedicated Dive bomber would be the Su-25 and A-10.

They enter shallow dives to put their cannon on target and/or dropping iron bombs. They can also toss iron bombs toward a target by a sort of "reverse dive" where they'll pull up at the point of release in order to broadcast the bomb(s) into defended areas.

 

[Retattack]

Is dive bombing a lost art for modern (large) air forces? Has that role been totally superseded by modern munitions?

The recent conflicts are so atypical that it's hard to draw conclusions. The recent Southwest Asia conflicts were basically no threat, but also zero risk acceptance, so most planes were trying to stay out of the AAA/small arms envelope with very high (10K'+) releases. Talked to a few guys who've done it fairly recently, and they all say there's minimal diving, though sometimes they "dip" slightly when releasing, usually in the 20K' range, always with guided munitions. Had one A-10 guy with slightly more dated experience, he said they just didn't loiter too long in the target area (and obviously, if you're using the gun, which he said they did, you have to get down in everybody's envelope). We still have some very capable dive bombers (esp. F-15E, F-16 and F-18), but I don't think anybody actually does it any more (except for practice, and anecdotal reports suggest that's minimal).

The Russian evolution is the opposite (AFAICT) with both sides using the traditional Soviet doctrine SAM airspace denial and very high threat. Judging by media reports, most of what they're using are standoff weapons, with no real attempt to achieve the level of air superiority needed for high volume dive bombing.

The trend is toward stealthier aircraft with internal bomb bays, which tends toward a limited number of smart munitions. I'd expect that to continue, but who knows?

 

[OldGeezer]

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.

Wow, I haven't thought about ARBS in decades! I spent the 1980s working AV-8B and potential (but never built) derivatives at McDonnell Douglas, and I remember having mixed feelings when they replaced ARBS with radar. I vividly remember the briefing we got on one live fire exercise which had to be truncated because all of the targets had been destroyed on the first day, thanks to ARBS. And speaking of A-4s, a photo from the Vietnam War still sticks in my mind, of one going straight down toward an army barracks near Hai Dong - dive bombing's twilight era for sure, as far as I know.

 

[Ivan1GFP]

Hello Retattack,
A few years ago I was quite interested in the SBD and some of what I found is not quite in agreement with what I have seen here.
First of all, the aircraft's attitude in the dive was very near vertical but the path it took was about 70-75 degrees from horizontal. That would explain the negative AoA you mentioned.
The second factor was that the SBD was not really able to keep its speed down in a long dive. It would gradually accelerate to about 400 MPH by the time it pulled out.

- Ivan.

 

[GrauGeist]

Not with those huge dive flaps deployed, it didn't.
The dive speed was close to a consistent 270mph.

 

[Retattack]

First of all, the aircraft's attitude in the dive was very near vertical but the path it took was about 70-75 degrees from horizontal. That would explain the negative AoA you mentioned.
The second factor was that the SBD was not really able to keep its speed down in a long dive. It would gradually accelerate to about 400 MPH by the time it pulled out.

The AOA charts max out at just over 5 degrees, so that seems a relatively minor adjustment to the dive angle. And that airspeed is much higher than any other I've seen cited. Do you have a reference?

 

[Ivan1GFP]

The AOA charts max out at just over 5 degrees, so that seems a relatively minor adjustment to the dive angle. And that airspeed is much higher than any other I've seen cited. Do you have a reference?

Unfortunately I do not have a reference handy. A few years back, I had three computer failures in the space of about 8 or 9 months. One was the repository for several thousand books and articles, manuals, flight reports and such.
I do remember that two of the references I used at the time were a Crowood book and Eric Brown's Wings of the Navy.
To GrauGeist,
Keep in mind that the lower dive flaps are just perforated landing flaps and the uppers are no bigger and missing the center section.

- Ivan.

 

[GrauGeist]

Keep in mind that the lower dive flaps are just perforated landing flaps and the uppers are no bigger and missing the center section.

The Dauntless had some of the largest dive brakes on any dive bomber built and 400 mph would exceed the dive speeds of other dive bombers of the day.

The Ju87, which was heavier and had underslung "fence" flaps would reach a max. of about 370mph in a vertical dive.

The A-36, was was much faster as well as cleaner in it's aerodynamics, reached a max. of 390mph in a dive with it's "fence" style dive brakes deployed.

As for the SBD's dive brakes: yes, the lower portion was extended to a limited degree when landing, but the lower flaps extended to it's maximum extension when applied as brakes (along with the upper panels).

 

[Retattack]

I do remember that two of the references I used at the time were a Crowood book and Eric Brown's Wings of the Navy.

At the risk of belaboring the point, I think this falls into the category of a bold claim that requires more than the usual amount of proof. Even if you have a test pilot documenting a 400 knot dive, it's hard to see how that trumps the recollections of pilots who actually used it in combat. Moreover, what we know about the standard open cockpit makes that airspeed doubly dubious. I've flown with an open cockpit in the landing pattern (in a T-28B), and even that is pretty loud and interesting. It gets a lot more so as airspeed goes up. From Dusty Kleiss's book:

At full dive speed, an SBD dropped at 240 knots, or 275 miles per hour. Even a typical, "perfect" dive was hard to endure. Air resistance buffeted the plane and deafened our hearing. We had to keep our cockpits open during a dive, so the noise of the wind drowned out nearly all other sound. With one eye on the bomb scope, we adjusted the dive so our target was centered and had no tendency to drift up and down, or left or right. Our other eye glanced at airspeed and other instruments, assuring us that our dive brakes were working. Mainly we watched the altimeter, which spun like a top but was inaccurate by 1,000 feet. If it spun past 5,000 feet we knew it just passed 4,000. We required 1,500 feet for normal pullout and another 1,000 feet to stay above bomb fragments. A quick pull on the manual release handle gave each pilot a jolt as the undercarriage bomb—either a 500-pounder or a 1,000-pounder—pivoted "downward" (really behind the plane) to clear the propeller. To pull out, we pulled smoothly on the stick, which resulted in 6 to 8 g's worth of pressure. (At 6 g, this means that if a pilot, his parachute, and his flight gear met the design weight of 200 pounds, then he pushed down on the seat with a force of 1,200 pounds.) Once we had pulled out into a level flight, we closed our dive brakes, swinging those big perforated flaps flush with the trailing edge of the wing, accelerated to full throttle, set high RPM (rotations per minute) on the engine, and headed for home.

The handbook specifies diving is permissible "with or without the use of the diving flaps," and that range of airspeed wouldn't surprise me with the flaps retracted. If so, though, I'd expect the canopy to be closed with the oft-cited windshield fogging issues.

 

[PStickney]

Wow, I haven't thought about ARBS in decades! I spent the 1980s working AV-8B and potential (but never built) derivatives at McDonnell Douglas, and I remember having mixed feelings when they replaced ARBS with radar. I vividly remember the briefing we got on one live fire exercise which had to be truncated because all of the targets had been destroyed on the first day, thanks to ARBS. And speaking of A-4s, a photo from the Vietnam War still sticks in my mind, of one going straight down toward an army barracks near Hai Dong - dive bombing's twilight era for sure, as far as I know.

Somewhere in my collection of photos, I have one of a KA-3B doing a 45 degree dive run - those big speed brakes fully extended) on some island or coastal target on the Tonkin Gulf.
This was, or course, in the early days, when there wasn't mich opposition, and it really sank in that they needed large-ish tankers rather than Medium Bombers.

 

[Retattack]

Somewhere in my collection of photos, I have one of a KA-3B doing a 45 degree dive run - those big speed brakes fully extended) on some island or coastal target on the Tonkin Gulf.
This was, or course, in the early days, when there wasn't mich opposition, and it really sank in that they needed large-ish tankers rather than Medium Bombers.

Did a night refueling off one in the mid-eighties . . . reserve squadron (out of Alameda?) needed a tanker requal. Don't remember much about it, except it was a very weird feeling, getting right in under that big tail. We had buddy stores but never used them, and tanking off the big guys was never so claustrophobic.