A proper heir to the SBD

[tomo pauk]

Unless you use a time machine you don't get the better cowls/exhaust in production in early 1942.

NACA report, dated November 1940, where XP-41 gains 18 mph by implementation of individual exhaust stacks: link
NACA was also doing the similar tests with XP-42 in winter of 1941/42.

 

[VBF-13]

F6F held 250 gal internal, An SB2C carried 330 gals internal.
Ranges were close, until you start hanging bombs off the bottom of the F6F.
The fighter bombers worked at short range and worked very well. For long range?
Until the Japanese forces were degraded you need both. Or you need a squadron of F6Fs with a drop tank and one bomb each escorted by a Squadron of fighters in order to reach the target. If the fighter bombers drop bombs and defend themselves the target was not get bombed and the defending forces can claim a successful defense.

Obviously things changed from 1941-42 to 1944-45 but it wasn't just tactics/technique.

They'd come in with fighter cover just like any dive-bomber squadron would. They'd use their belly-fuel on the way in while not engaging anything and drop it once they reached the target and engaged the CAP. At that point they'd be just like any SBD squadron coming in with fighter cover. A squadron of bomb-armed F6s scattered among a squadron of F6 fighter-cover is feasible as such for the 1200-mile hops. The drop tank isn't a liability because it's gone when they need it to be. They go into their dives as bombers and come out as fighters. This should have been utilized more. All these pilots knew how to do it, it's right there in their training logs.

 

[EwenS]

The F6 was already a crack dive-bomber right out of the box. That's where the B in VBF comes from. The way many are accustomed to thinking of these one would think they were in VF squadrons. Those were the F4Us. The F6 didn't need a second seat because it could take care of itself. The SBDs were the ones that needed to run from the carrier fighter CAP. You look at the training logs in these F6s and you'll see all the bombing runs they did. Still, instead of thinking of them as bomber-fighters, which they were, many still conceive of them as just fighters.

Looking at the air group compositions in the final few months of the war, they fell into 3 groups:-

Those with VF AND VBF equipped with the F6F-5. Like CVG-13 earmarked to go aboard the Bunker Hill when she completed her repairs in Sept 1945.

Those with VF AND VBF equipped with the F4U

And finally those equipped with a squadron of each type. In those cases the VF unit was flying the F6F-5 and the VBF unit the F4U. The only exception was CVG-19 where VF-19 was trading its F6Fs for F8F-1 Bearcats between May & Aug 1945.

Source: Location of US Naval Aircraft reports produced roughly fortnightly from various USN commands including COMAIRPAC.

Edit:- I would add that, by that stage of the war, there was little difference between the missions being flown by VF and VBF units on the carriers, due to the lack of enemy air opposition.

 

[VBF-13]

Looking at the air group compositions in the final few months of the war, they fell into 3 groups:-

Those with VF AND VBF equipped with the F6F-5. Like CVG-13 earmarked to go aboard the Bunker Hill when she completed her repairs in Sept 1945.

Those with VF AND VBF equipped with the F4U

And finally those equipped with a squadron of each type. In those cases the VF unit was flying the F6F-5 and the VBF unit the F4U. The only exception was CVG-19 where VF-19 was trading its F6Fs for F8F-1 Bearcats between May & Aug 1945.

Source: Location of US Naval Aircraft reports produced roughly fortnightly from various USN commands including COMAIRPAC.

Edit:- I would add that, by that stage of the war, there was little difference between the missions being flown by VF and VBF units on the carriers, due to the lack of enemy air opposition.

Well sure they mixed these up, that's hardly being full of any news. F4Us could dive-bomb, they just didn't off carriers. F6, which carrier-qualified earlier, were largely in VBF squads. They should have been more utilized for dive bombing, is what I'm maintaining, they were made for it, but they weren't.

 

[Conslaw]

To meet the timing goal of the problem, maybe it would be better to use a pair of R1820 or R1830 engines. The Navy had not ruled out compact two-engined aircraft for carrier use, hence the XF5F.

 

[Shortround6]

To meet the timing goal of the problem, maybe it would be better to use a pair of R1820 or R1830 engines. The Navy had not ruled out compact two-engined aircraft for carrier use, hence the XF5F.

Problem is that the gross weight of the aircraft is limited by the length of the flight deck for flying off, by the catapults for using the catapults, and by the arresting gear.
Using twins may very well solve the first problem. However using 2600-3000lbs worth of engines instead of a 2000lb engine (and two props in proportion) means you have to loose over 600-1000lbs out of the gross weight of the airplane and that is not counting the greater structural weight.
so what do you take out
Fuel?
Bomb load?

The XF5F-1 was slightly heavier than the XF4U-1. The XF4U-1 porked up a bit. The XF4U-1 used an engine around 400lbs heavier than the R-2600s. The XF5F-1 used the lighter of two small engines (by over 150lbs per engine)

 

[Barrett]

Two current references:

U.S. Navy Attack Aircraft, 1920-2020

The U.S. Naval Institute provides an independent forum for those who seek to advance and strengthen the naval profession.

www.usni.org

US Attack Aviation: Air Force and Navy Light Attack, 1916 to the Present|Hardcover

Attack aviation is intense and dangerous. It necessitates the direct engagement of ground targets at low altitude. Attack aircraft are usually fighters or fighter-sized aircraft, with one or two engines, and one or two crew. This work provides an overview history of American attack aviation from...

www.barnesandnoble.com

I've been in occasional contact with BGEN Head. Good troop: A-1 aviator in SE Asia plus Fighterjets.

 

[elbmc1969]

They did wring the problems out of the SB2C in the end, resulting in a pleasant and effective aircraft.

It just took too long.

Anything else that you try to develop runs into problems of known unknown (stability, handling) and unknown unknowns (what failure mode will Murphy inflict?). You may end up with something better, you may end up with something worse.

 

[yosimitesam]

What about fitting a bigger engine in the Dauntless until the avenger comes on board?.

A more powerful engine would not have helped, much. It would have increased the payload some and reduced the range some (more thirsty engine), but the basic physical aircraft design "sets" the maximum speed, more or less. This is due to the "power-cube relationship" which applies to objects moving through a fluid (liquid or gas), i.e. to aircraft and ships. The required power is proportional to the cube of the velocity. For example, the SBD-5 had a top speed of about 255mph with the 1600hp (max) R-1820. Assuming the engine could be replaced with an R-2800 having (magically) the same weight and dimensions of the R-1820 (maintaining the same weight and "geometry" of the aircraft), the increase in top speed would be approximately: (cube-root(2100hp/1600hp)) x 255 = 280mph, or about a 9-percent increase in top speed for a 31% increase in power. To increase the SBD-5 top speed to 350mph, for example, would require a "magic" engine of the same weight/size of the R-1820 that produced (350/255)^3 x 1600 = 4,137hp (!). To increase the max speed of an object in a fluid by 50% requires an increase in power by a factor of 3.38 (1.5 cubed). This is why aerodynamic design in aircraft (and hull design in ships) is so critical. The design shape is where the "max speed" values are ultimately throttled by the power-cube relationship. "Throttle" pun intended.

 

[Shortround6]

Uh, Sam, the R-1820 gave 1000-1350 hp in various versions of the SBD. However, to your point, the speed never varied much. When they got the newer engines something was added (or several somethings) that added a bit more drag.

 

[GrauGeist]

The P-47 had all the aerodynamics of a brick, yet seemed to do ok.

 

[Shortround6]

The P-47 gets a bad rap.
Anybody (well aside from Brewster) can make a small airplane go fast with enough power (think Groundhog).
making big planes go fast is a lot trickier.
P-47 has a lower flat plate area (about 25%) than an F4U-1 or an F6F-3.
The P-47 has a flat plate area about 12% larger than a P-40 (model unknown) so considering the size of the P-47 that is not too bad.
The Buffalo had a flat plate area 2% less than the P-47.
There is a genuine cinderblock.

 

[GrauGeist]

Agreed about the F2A, though Grumman also had a tendency to design barrel shaped aircraft, too.

 

[tomo pauk]

For example, the SBD-5 had a top speed of about 255mph with the 1600hp (max) R-1820.

Thanks for the math behind all the numbers.
As noted by a fellow member above, 1350 HP was the best the SBD could've hoped for. At the rated altitude (15600 ft with ram effect), it was 1000 HP for 262 mph clean. Bomb 'steals' 9-11 mph at high speed at rated altitude when normal power is used.
Early SBDs were making 253 mph clean on 800 HP at 15600 ft.
Engine upgrade options for the SBD include earlier introduction of 1200 HP R-1820s, two-speed R-1830s, 2-stage R-1830, 2-stage R-1820, R-2000, and the turboed engine, preferably the same as used on the Curtiss SC-1.
Granted, we will have a hard time to have a 300 MPH SBD (level flight) unless it is powered by some engine type usually not associated with the naval attackers, like a 2-stage V12, or a turboed V12. Bomb in the slipstream is even more of an airbrake as the desired speed increases.

 

[wlewisiii]

That last line makes me wonder. The SDB probably didn't have room or weight allowance for a proper bomb bay but what about a semi-recessed bomb bay where half the bomb was inside the aircraft to decrease the amount of drag out in the slipstream? Similar to how some modern fighters have recessed missile hardpoints to reduce drag?

 

[tomo pauk]

That last line makes me wonder. The SDB probably didn't have room or weight allowance for a proper bomb bay but what about a semi-recessed bomb bay where half the bomb was inside the aircraft to decrease the amount of drag out in the slipstream? Similar to how some modern fighters have recessed missile hardpoints to reduce drag?

I like your idea, especially since it turns the shortcoming of the R-1820 (it's great diameter) into an advantage.

 

[GrauGeist]

The SBD's main fuel tank was beneath the cockpit floor.

 

[tomo pauk]

An aircraft with the nose like on the CW-21 might've qualify, per what is posted at #35 here?
side elevation
(yes, the exhausts will need to be routed away from the bomb)

 

[SaparotRob]

I never would have thought of that.

 

[tomo pauk]

I never would have thought of that.

Really, not my idea - eg. Ju 87s used the cooling system for the same purpose (by accident more than by design? - there was a lot of draggy bits and pieces already on it). Possibly also the He 118, but good luck finding the picture of a bombed-up He 118.
The number of 1-engined aircraft that used part of powerplant to 'hide' the whole bomb bay was even greater - Henley, D4Y, a lot of USN attackers...