USAAF Attack & Light Bombers: Needs & Desires

[Zipper730]

I was thinking about the various attack planes and bomber concepts whipped up during WWII and how they conformed with what we needed and wanted.

I could be missing a few designs here and there, but I remember a few off the bat

USAAF

• A-26 Variant(s)
  • There was one variant which had a redesigned spinner and a jet-engine in the lower rear fuselage for increased speed over target
  • Another just had the redesigned cowlings
• XA-39: Single engine attack/dive-bomber
  • Crew was a single pilot, no rear-gunner
  • Powerplant was 1xR-2800
  • Equipped with 2x37mm+4x0.50 fixed
  • Top speed listed as 357 mph @ 16,600'
  • Range: 1400 miles
  • Could carry 3000-3200 lbs (6 x 500, or 2 x 1600) internally, probably a total of around 4000-4500 lbs total
• XF8B-1 Derivative: Single-engine level-bomber
  • A/C was originally intended for use as a fighter-bomber
  • Crew was a single pilot
  • Powerplant was an R-4360 driving a contra-rotating prop (2 x 3-blades)
  • Could carry up to 6400 lbs of ordinance including 2 x torpedoes; 3200 lbs of ordinance could be carried internally at maximum (2 x 1600 AP).
  • Top speed was around 450 mph with wartime emergency-power providing it had the same supercharging as the USN layout (2-stage, variable-speed).
  • Considering the proposal for use as a level bomber, I'm not sure if it was fitted with some kind of bombsight, or merely dropped at low altitudes.
  • Armament could either come in the form of 6x0.50, or 6x20mm
• XA-41: Single-engine attack/dive-bomber
  • Crew was a single pilot, no rear-gunner
  • Equipped with 2x37mm and a few 0.50's
  • Top Speed was 363 mph
  • Range: 800 miles while carrying 1000 lbs
  • Could carry 3200 lbs internally, 3200 lbs externally, with a maximum total load ranging from 4000-6000 lbs
• XB-42: Twin-engined level-bomber
  • Crew of 3
  • Powerplant were 2 x V-3420 driving three-bladed propeller-blades
  • Could carry up to 8000 lbs bombs normally, up to 10000 lbs (single bomb) if the bay doors were held open 6"
  • Defensive armament consisted of 2xturrets behind each wing, each with 2x0.50 with 500 rpg.
  • Armament could include a bombardier nose with 2 x 0.50" also present, as well as nose arrangements that included 8x0.50, 2x37mm+2x0.50, or 1x75mm+2x0.50
  • Had a defensive armament consisting of twin 0.50 in each wing pointed aft.
  • Top speed was 410 mph
  • Range or Radius (I forgot, it's been awhile) was 2500 miles with unspecified load
  • Notes: Double-Bubble canopy was replaced with single-bubble; to improve safety of bail-out, the propellers were rigged with an explosive charge to blow the blades off; XB-42A featured a pair of J30's under each wing.
• XA-43: Twin-engined attack/level-bomber
  • Crew of at least two
  • Jet powered: 4 x J35
  • Payload of 10000 to 12000 lb. if I recall right
  • Defensive Armament: Remotely controlled tail-turret
  • Offensive Armament: 6 x 15mm or 6 x 20mm + 4 x rocket-tubes
  • Radius at 35000 feet: 1000 miles
  • Radius at 10000 feet: Failed to meat the 600 mile figure
  • Notes: Was NOT the same as the XP-87; funding was used from the XA-43 to fund the XP-87

I'm probably missing a few designs, I omitted the XA-38 because it was cancelled simply because of engine demand.

 

[MIflyer]

In Europe, when they got the A-26 they found it was just as fast as a P-47 at low altitudes and cold carry a much heavier load of ordnance. They thought it might be possible to replace the P-47 in CAS with the A-26. But when they tried using A -26's on P-47 type fighter bomber missions they found it was a lot larger and therefore easier for the enemy to hit it with ground fire. I think the A-26 ended up being used more or less as a medium bomber, like the B-25 and B-26 and replaced both those airplanes starting at the end of the war. It replaced the A-20 during the war. I recall reading when they brought in the A-26's the A-20 crews deployed at forward bases in Europe were told to fly their A-20's to an airstrip in Scotland, where they stopped, advanced the throttles, jumped out, and let the airplanes run off the end of the runway and over a cliff into the ocean. No wonder we saw so few of those airplanes after the war.

At least one of the XA-41 aircraft had 4X37MM guns in the wings. It amounted to a USAAF AD Skyraider. It was not adopted because the USAAF found that the XA-41 needed a fighter escort, while P-47's and P-51's equipped with bombs could provide their own escort as well as act as attack aircraft. Of course, as fighters advanced in performance they got further and further away from the needs of the attack mission and in the 60's the the Air Force once again acquired dedicated attack aircraft, ironically starting with the A-1.

The XB-42 used two V-1710 engines driving a V-3420 gearbox. I guess they did that to keep a catastrophic failure of one engine from taking out the whole airplane as might occur with a single V-3420. It was designed for the long range heavy bombardment mission, as a cheaper and faster alternative to the B-29, operated rather like the DH.98. Of course the jet engine doomed it; although they did build a jet powered version that proved to be a nice airplane for testing engines, outrunning jet fighter interceptors was no longer possible. I posted some 1940's vintage articles on it a while back.

 

[Zipper730]

In Europe, when they got the A-26 they found it was just as fast as a P-47 at low altitudes and cold carry a much heavier load of ordnance.

True, but it was larger and probably less maneuverable when loaded (maximum g-limit) though I could be wrong. I'm curious which costed more, a P-47D & N, or an A-26?

I think the A-26 ended up being used more or less as a medium bomber, like the B-25 and B-26 and replaced both those airplanes starting at the end of the war.

Basically the B-26 was a medium bomber, the B-25 was originally conceived as a light bomber, then respecified into a medium bomber and classified as such; the A-26 was basically designed for the A-20's mission, though better defended, with a heavier load: It was still classified as a light-bomber because the bomber guys always wanted every new bomber design to be bigger, faster, and further flying.

For heavy bombers, and medium-bombers this sort of made sense, but for the lighter bombers: It seemed to produce designs that were excessively large, and expensive.

A-20 crews deployed at forward bases in Europe were told to fly their A-20's to an airstrip in Scotland, where they stopped, advanced the throttles, jumped out, and let the airplanes run off the end of the runway and over a cliff into the ocean.

If that's true, it's such a waste. A lot of the metal used in that A/C could be recycled.

At least one of the XA-41 aircraft had 4X37MM guns in the wings.

I'm curious why they'd use such heavy ammunition -- it didn't have enough firepower to be effective against tanks as far as I know.

It amounted to a USAAF AD Skyraider.

Not exactly, it was slower, had less range, though an internal bay was a nice touch.

It was not adopted because the USAAF found that the XA-41 needed a fighter escort, while P-47's and P-51's equipped with bombs could provide their own escort as well as act as attack aircraft.

I'm not sure if that was true, the XA-41 and could turn inside of the P-51B (not sure if the XA-41 was unarmed or loaded). Regardless, the P-47's often flew with top-cover, so they profited from escorts as well.

As for acquiring attack aircraft again, that sort of came out of McNamara, it seems at least...

The XB-42 used two V-1710 engines driving a V-3420 gearbox.

Actually, I thought it was 2 x V-1710 at first; but I remember being told it was V-3420

Of course the jet engine doomed it; although they did build a jet powered version that proved to be a nice airplane for testing engines

Actually 2, the XB-42A and the XB-43...

I posted some 1940's vintage articles on it a while back.

That's cool

 

[tomo pauk]

[QUOTE="Zipper730, post: 1399994, member: 67843"

• XB-42: Twin-engined level-bomber
  • Crew of 3
  • Powerplant were 2 x V-3420 driving three-bladed propeller-blades
  • [/QUOTE]

XB-42 was powered by two V-1710 engines.

 

[MIflyer]

See a

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[Zipper730]

See

Regarding the XA-41: Was this combat-range figure based on payload or not? Most sources I got specify a range of 800 miles with 1000 pounds of bombs.

Regarding the XB-42: I have heard some figures for the XB-42 having a having a radius of action of 1800 miles

 

[fubar57]

I have the XB-43 having a range of almost 2,500 miles

 

[Zipper730]

I have the XB-43 having a range of almost 2,500 miles

The XB-43 is a different aircraft than the XB-42, particularly in that it is jet powered.

 

[MIflyer]

First flight of the XA-41 was on 11 Feb 44 at Lomita, CA. That would have to be Lomita Flight Strip, later Torrance airport and now known as Zamperelli Field. I got my pilot's license there in 1982. I am surprised that was the airfield used. It was a training base for P-38's and then P-51's. I guess the XA-41 must have been built near there.

 

[Zipper730]

While a little off topic, I was curious about something regarding a comparable aircraft to the XA-41: The A-1 Skyraider

According to Joe Baugher's website...

• XBT2D-1: Range 1430 -w- 1 x Torpedo
• AD-1: Range 1940 -w- 2000 lbs of bombs

This would be combat range right (i.e. 2 x combat radius)?

 

[Shortround6]

Not quite. If it doesn't say COMBAT RANGE, then it probably isn't.
Combat radius will include reserves, a combat allowance, and perhaps a few other things (like climb to operational altitude)

"Range" unless it specifically says so, does not include any of those things.

For instance see:
http://www.alternatewars.com/SAC/XBT2D-1_ACP_-_10_August_1944.pdf

Please note Joe Baugher is not listing the conditions of that range, like gross weight and if drop tank/s are being used while carrying bomb/torpedo load.

 

[MIflyer]

The XB-42 was envisioned by Douglas as an alternative to the B-29 for the Marshall Is to Japan mission, although using more aircraft flying at a somewhat higher speed. The Aviation article says it has a 5000 mile range, so that sounds about right. I have already posted the B-42 design analysis that provides more data.

Note that the XA-41 uses an R-4360 rather than the AD's R-3350..

 

[Zipper730]

Not quite. If it doesn't say COMBAT RANGE, then it probably isn't.

I also think Joe Baugher miswrote the 1940 mile figure, because none of the other designs are that high up. I think he meant "1490" and got 4 & 9 backwards.

Combat radius will include reserves, a combat allowance, and perhaps a few other things (like climb to operational altitude)

The listed figures on the chart you gave me seems to indicate that combat range is 80% of normal range, so combat radius is 40% of the range.

The XB-42 was envisioned by Douglas as an alternative to the B-29 for the Marshall Is to Japan mission

I thought the specification was to do what the Mosquito could do, or faster, with twice the load and self-defending armament? So the idea was actually an alternative to the B-29 that could do what I basically wrote? Why was it classified as a light and not a medium bomber with an 8,000 pound bomb load?

The Aviation article says it has a 5000 mile range, so that sounds about right.

If the combat radius of a bomber is 0.4 that of the range that would yield a radius of 2000 miles...

Note that the XA-41 uses an R-4360 rather than the AD's R-3350..

I'm aware of that, how do the SFC figures compare? From what I remember, the R-3350's used on the AD-1 used a twin-speed supercharger?

 

[Graeme]

I also think Joe Baugher miswrote the 1940 mile figure, because none of the other designs are that high up. I think he meant "1490" and got 4 & 9 backwards.

No, Baugher hasn't got it wrong - look at his bibliography - he's using Wagner....

 

[MIflyer]

Check out the cruising speed on the AD versus that on the XA-41.

 

[Zipper730]

Check out the cruising speed on the AD versus that on the XA-41.

The XA-41's listed cruise is 294 mph; the AD-1 has a listed indicated airspeed of 185 mph which would at 15000 come out to 233 mph and, with 164 mph as one of the SAC sheets listed, would come out to 207 mph. With ingress altitude listed at 15000 and egress at 5000 feet: You would see speeds that would be around 177-199 mph

Sea level maximum for the AD-1 is 357 mph, and 333 mph for the XA-41

Edited 5/2/21: Really botched the IAS/TAS conversion.

 

[MIflyer]

I would assume that performance figures would use true air speed, not IAS.

 

[Zipper730]

Deleted

 

[MIflyer]

Well an airplane can "cruise" at just about any speed, from just above stalling to full power. I would guess that the XA-41 speed given is maximum cruising speed while the AD speed given is economy cruise.

I just read where in WWII a Mossie night fighter was caught in a massive thunderstorm and could not climb. Finally the radar op yelled at the pilot, "Go through the gate with the throttles so we can climb. We can't go any lower! We don't even know where we are!" The pilot replied, "I did that ten minutes ago and we still can't climb!"

 

[Zipper730]

Well an airplane can "cruise" at just about any speed, from just above stalling to full power. I would guess that the XA-41 speed given is maximum cruising speed while the AD speed given is economy cruise.

Apparently the XA-41 had a three-speed single-stage supercharger, I'm not sure why you'd gear the high-speed setting for around 15,000 feet.

I just read where in WWII a Mossie night fighter was caught in a massive thunderstorm and could not climb.

Ice on the wings?