Vought's SB2U - Not that bad?

[H_K]

I know the SB2U often comes up on lists of "worst aircraft"... but was it as bad as its reputation? Here's what the pilot with probably the most combat experience on the type thought of it:

As a whole, the V.156 was an excellent aircraft - fast, reliable, stable, with a good bomb load and capable of operating from very small airfields, but very vulnerable.

As a carrier scout-bomber, it was one of the best of its time. As a dive bomber, it was superior in all respects (except for the machine gun armament) to the JU87. It had a significant speed advantage carrying the same bomb load, and could dive at all angles up to the vertical, thanks to its very effective dive brakes which allowed it to slow down and drop its bombs at low altitude. (...)

It enjoyed good maneouvrability, though inferior to that of a single-seat fighter like the Morane. The fuselage and engine were of very robust construction. During 10 months of operations, we experienced not a single serious mechanical incident. (...)

In summary, in 1940 the V.156 was a capable but still rudimentary precursor to the much more powerful fighter-bomber types that achieved excellent results from 1944 onwards, using the doctrine that we helped to establish.
Lieutenant Mesny, squadron leader of the Aeronavale's AB.1

Sort of busts the myth that the SB2U was a terrible dive-bomber, doesn't it? He goes into more details, which I'll post later.

 

[Shortround6]

A lot of those "worst" lists include aircraft that went into combat when they should have been being replaced due to age, both of the aircraft and the design.
What was "good" aircraft in the beginning of 1938 or even the spring of 1940 would not be looked at so kindly in the spring/summer of 1942 if it had few if any improvements.
Imagine US opinions of the Hawker Hurricane IF they had used MK Is with fixed pitch props during the Battle of Midway?
There is only so much you can do with 750-825HP and a 1942 dive-bomber should have had 1100-1200hp .

Unless somebody can find examples of bad flying characteristics (not just low performance) or lack of structural strength I would agree that it doesn't belong on most such lists.

 

[Capt. Vick]

IIRC The French version was different from the US Navy version. The dive breaks were entirely different and in a different location and it didn't carry it's bomb load under the fuselage, but under the wings. So even though it says that it can carry the same bomb load as a Ju 87, which I have a hard time understanding, how was that load concentrated? Smaller bombs equaling the same weight would not be as effective. Not saying it was a bad plane at all, just saying that an apples to apples comparision this is not.

 

[FLYBOYJ]

I don't think it was a bad plane, but it sat in the shadow of the SBD. It seemed to be a bit underpowered but offered lighter wing loading and a slightly better service ceiling than the SBD. Lots of fabric, it was a half a step behind the Dauntless and it seemed that aircrews that flew both liked the SBD better.

 

[H_K]

Yes, but how much of the SBD's popularity came down to the fact that it had dive brakes... and that the SB2U didn't?

Though this could be fixed, see the French V.156 Fs... and suddenly the pilot opinions were a lot more positive. And as an admiral, I'd have wanted the SB2U because of its folding wings.

 

[FLYBOYJ]

Yes, but how much of the SBD's popularity came down to the fact that it had dive brakes... and that the SB2U didn't?

That's a question to pose to those who operated both aircraft, and AFAIK only VMSB-241 operated both aircraft. Wikipedia references these two publications for some of the crewmember's comments;

^ O'Rourke, G.G, CAPT USN. "Of Hosenoses, Stoofs, and Lefthanded Spads". United States Naval Institute Proceedings, July 1968.
^ Spangenburg, Walt, CAPT USN. "Comment and Discussion". United States Naval Institute Proceedings, October 1968.

Though this could be fixed, see the French V.156 Fs... and suddenly the pilot opinions were a lot more positive. And as an admiral, I'd have wanted the SB2U because of its folding wings.

That might be a player but the SBD had almost twice the range and carried a larger bomb load.

 

[H_K]

That might be a player but the SBD had almost twice the range and carried a larger bomb load.

Comparing the SACs for the SBD-1 vs SB2U-1, the gap in performance doesn't seem that big?

The SBD clean had a speed advantage of 3-4mph at most altitudes, increasing to ~10mph above 16,000ft. Range advantage clean was about 15%. The SBD's speed advantage increases somewhat as you add weight (extra fuel tanks, bombs, protection), to 10-20mph... so it seems like the SB2U's bomb crutch had a fairly big drag penalty.

Take-off runs are the same, and stay the same as you add weight, so practical range bomb load wouldn't be much different (since carrier deck run was usually the limiting factor).

So as I've said, the only clear weakness I'm finding is that the SB2U "couldn't dive" according to unanimous pilots' reports... obviously a huge dealbreaker, yet it was fixable with a simple 140lb modification tested by Vought and adopted by the French!

 

[FLYBOYJ]

I think one would also have to look at performance charts for take off, climb, fuel consumption. etc., as it seems the SB2U was a bit underpowered, that too mat have played into the decision to go more with the SBD. With more available thrust, the SBD may have seemed like the better performer of the two

 

[H_K]

Squadron Leader's Mesny's pilot report continued... now he explains why the SB2U was ineffective in French service. Seems like none of it had to do with the aircraft proper.

Machine Guns
The mechanical feed and trigger mechanism of the forward firing machine guns was constantly breaking down. They were so erratic that we gave up on getting more than 10 or 12 rounds out of them before they'd jam. We never were able to use them in combat. The rear machine gun was the only one to function properly, thanks to its simpler setup, but was of very marginal effectiveness. We were completely defenseless against enemy fighters.
[The guns were French Darne 7.5mm - seems that problems had been known since the mid-1930s and never been fixed]

Bomb racks
The bomb racks were heavy and draggy. The centerline bomb crutch was cumbersome and so unreliable using 75kg [175lb] bombs that we had to give up on vertical dive bombing entirely and use less precise glide bombing tactics.
[The bomb racks were French Alkan-made. Seems like the US refused to supply its standard bomb crutch, due to export/neutrality law restrictions?]

Radios
The [French] radios would stop working after 20-30 minutes in the air. We had to make do the old fashioned way - communicate by rolling our wings.

Protection
We lacked any crew armor, the fuel tanks were not protected, and the rear fuselage and parts of the control surfaces were made of fabric. This defect made it particularly vulnerable to AA or machine gun fire, leading to the squadron being almost wiped out on our 4th mission.
[Note that this contradicts reports of the squadron's aircraft surviving many AA hits, with only one actual loss to AA fire]

Operational Reasons

• 
  Such high-risk missions should have required a fighter escort at all times, but this operational concept was not mature in 1940. On the 21st, we were supposed to destroy a bridge on the Oise river [but the rendez-vous with the RAF Hurricane escort failed]. We were intercepted en route by enemy fighters [twelve Bf-109], and lost 7 [more likely 5] out of 11 aircraft.

• Insufficient training for overland bombing operations, which was not the squadron's intended mission and for which we lacked doctrine.

• The bombs [150kg depth bombs] used were designed for anti-submarine operations.

• We would launch willy-nilly in search of armored columns, artillery batteries, but couldn't find them due to the lack of a close air support coordinating function (created only later). Diving from high altitude (4,000m), we would have had the benefit of surprise. Unfortunately, since we couldn't find our targets, we had to fly low at 1,200m, which both robbed us of surprise and prevented steep dive bombing.