The XA-38 Grizzly

[SamPZLP.7]

The United States Army Air Force needed a ground attack aircraft for the planned invasion of Japan. Beechcraft designed this aircraft in 1942 and its first flight took place on 7 May 1944. Armed with a single, forward- firing 75mm cannon and 6 .50 caliber machine guns, it was a true force to be matched. It was pretty fast, at a speed of 370 mph. The Grizzly had two Pratt and Whitney R-3350-43 engines. During testing, the aircraft performed better than expected. If it weren't for wartime priorities, the aircraft would have been produce in large numbers, but the B-29 had the priority for the R-3350s. The development was cancelled for that reason and only two were ever built. They both had an unknown fate.

 

[GregP]

It was a formidable aircraft. Here is a 3-view I did of it:

A 75 mm cannon hit is quite devastating and hits from a 75 plus 6 50-cal would have done damage to almost anything.

 

[vikingBerserker]

It would have been interesting.

 

[muskeg13]

different mission, but...looks like Aircuda II. Actually, a 75mm isn't very impressive against ground targets, and the rate of fire had to be quite slow. A slew of 20-30mm cannon would be much more effective.

As designed, with only 2 forward firing .50 Cals (+the 75mm), a standard P-38, P-39, P-47, B-25J , or even any of the 6x.50 pursuit planes would be a better ground attack aircraft.

 

[tomo pauk]

Wasn't Beech approached (among some other companies) with a proposal to license build Mosquitoes? They said 'it can't be done, the wooden hi-speed A/C will never going to work'?

 

[wuzak]

Wasn't Beech approached (among some other companies) with a proposal to license build Mosquitoes? They said 'it can't be done, the wooden hi-speed A/C will never going to work'?

Yes, Beech was one of 5 comanies asked to look at plans of the Mosquito with a view to having US licence production.

 

[tomo pauk]

Do you know what other companies were approached? What were the answers, apart from the obvious 'can't be done'?

 

[T Bolt]

The B-25H had better forward armament (2 additional .50's) and was already available although it was slower. There were also overheating problems with the earlier R-3350 engines that plagued the B-29s resulting in engine fires that was not resolved until after the war. Those problems had to be endured with the B-29 because it was essential to the war in the Pacific, bit why have to deal with them for an aircraft similar to one that already existed.

 

[muskeg13]

By this late in the war, hadn't air-to-ground rockets proved their utility and destructivness? I'd guess that a 5" rocket would be more effective than a 75mm cannon shell. Rocket racks had already been installed on a number of commonly available aircraft, the P-47 and F4U for example. Adapting numerous existing airframes to accept rockets expanded their mission capabilities, making them multirole fighters. The A-38 concept seems like a pretty expensive and maybe not so effective solution for ground attack, but it looks kinda Buck Rogerish.

 

[wuzak]

Do you know what other companies were approached? What were the answers, apart from the obvious 'can't be done'?

Beech
Curtiss Wright
Fairchild
Fleetwings
Hughes

 

[wuzak]

By this late in the war, hadn't air-to-ground rockets proved their utility and destructivness? I'd guess that a 5" rocket would be more effective than a 75mm cannon shell. Rocket racks had already been installed on a number of commonly available aircraft, the P-47 and F4U for example. Adapting numerous existing airframes to accept rockets expanded their mission capabilities, making them multirole fighters. The A-38 concept seems like a pretty expensive and maybe not so effective solution for ground attack, but it looks kinda Buck Rogerish.

Cannons would be more accurate. But they also are much heavier to carry, and make the aircraft more vulnerable.

 

[GregP]

Muskeg,

Let's say we disagree on the A-38. I'd love to have seen it built.

History says otherwise, though, so the conjecture is pure what-if ... I might point out the B-25H models were devastating to Japanese ships they attacked as well as the few ground targets in the middle of an ocean, so I'm not too sure where your information comes from.

Welcome to the forum.

- Greg

 

[GrauGeist]

By this late in the war, hadn't air-to-ground rockets proved their utility and destructivness? I'd guess that a 5" rocket would be more effective than a 75mm cannon shell. Rocket racks had already been installed on a number of commonly available aircraft, the P-47 and F4U for example.

Nothing punches holes in things like a 75mm...

The HVARS were effective and did well enough against fixed targets, but they were dumbfire and when you needed accuracy and heft, the 75mm got it done.

 

[muskeg13]

I'm a retired artilleryman by trade, so I know a bit about the actual effect of cannon shells. History actually tells us that aircraft cannon used against ground or naval targets were largely inneffective, and the 75mm is particularly puny. An aircraft can't carry the weight of a cannon, or absorb the recoil, to fire a shell large enough to really be effective.

If you want examples of what it takes and the limitations of cannon, read anything about employing submarine guns against naval targets. It sometimes took hundreds of hits by cannon far larger than any aircraft could carry to sink a ship. U.S. subs with 3 or 4 inch naval cannon were replaced by 5 inch cannon late in the war, but the whole idea of naval gunnery for subs was scrapped right after the war, due largely to ineffectivness.

Likewise, as good as 75mm B-25s were supposed to have been, why were they scrapped even before the war was over, and replaced with additional .50 Cal MGs?

The idea of aircraft cannon sounds cool, but it never really panned out. Otherwise, we'd have seen many more cannon armed aircraft.

 

[GregP]

Gotta' disagree. I worked with a guy in the 1980's who helped invent the B-25H and I saw the pics of what it did.

However, we all have our opinions.

ANd almost every aircraft in combat use today is armed with a cannon, usually a multi-barrel 20 or 30 mm unit, but often 37 mm or larger. In fact, I cannot think of a US warplane today in the fighter or ground attack role that is NOT cannon armed. Advances in powder, weapons, and projectiles have put the destructive power of cannons twice as large into smaller cannons, like the GAU-8 on the soon-to-be retired A-10.

I cannot think of an aircraft armed with a machine gun other than maybe some troop-carrying helicopters who only need to discourage small arms fire.

And nothing says the four other 50's on the A-38 cannot be pointing forward ... they are in turrets and forward is an optional direction.

 

[GrauGeist]

An aircraft can't carry the weight of a cannon, or absorb the recoil, to fire a shell large enough to really be effective.

There's a large number of Japanese transports lying on the bottom of the Pacific that would disagree with you, there...

The B-25G carried the M4, the H model had the lighter T13E1 which had a lower RoF. Yes the multiple nose-mounted .50s packed a punch, but the 75mm was devestating to shipping and hard targets in a way the concentrated firepower of the .50s could not match.

The Germans did a similiar configuration with the Ju88P series to be used against armor, but had less than satisfactory results because they were targeting AFVs...a much harder target to hit than a ship. Their solution was to use a twin BK37 setup and that proved successful.

 

[muskeg13]

I'm not saying 20 and 30 mm AUTOMATIC cannon are ineffective. Quite the opposite, particularly if they had been part of the A-38 design. 4 or more 20-30mm autocannon would have provided awesome firepower.

The only large caliber cannon (greater than 30mm) employed today are the 40mm and 105mm on AC-130s, which is a very specialized aircraft. However, in WW2 things were different. The 75mm used in the B-25 was manually loaded, and only fired a 14 lb projectile. It was slow to load.

Even if a new 75mm semi-auto cannon was envisioned for the A-38, there were better ways to accomplish the ground attack mission....napalm, dive bombing, rockets, even guided rockets (missiles) by the end of the war, and most of these munitions could be delivered by the tens of thousands of aircraft already in the inventory.

 

[GregP]

We have a basic disagreement with that. Any unguided munitions are much more inaccurate than a cannon and basically spray the target not any particular place. Guided missiles weren't worth a crap in Viet Nam and even later. What makes them better in WWII?

However, I would prefer and autoloader cannon, as you say. In the event, they didn't buy the Grizzly and with the state of the R-3350 in much of WWII, it's probably just as well. AFTER WWII it turned into a very relaible engine ... but combat hijinks would have quickly made the long TBO's a thing of the past even after WWII.

I asked the Sanders why they had an R-2800 in Argonaut (Reno racer) and the answer was, "We were tired of broken R-3350's!"

Maybe it would have done better with R-4360's.

 

[wuzak]

R-4360s would have made the XA-38 late in the war.

The British used the Mosquito FB.XVIII with 57mm autocannon against U-Boats and lighter warships, I believe to good effect. But they were generally superseded by rocket projectile firing aircraft.

 

[wuzak]

View: https://www.youtube.com/watch?v=M00f5RxhxLY