Stearman XA-21 – The One That Didn’t Make It

October 28, 2022

When the name Stearman comes up in aviation circles, well, it conjures to mind one particular aircraft – the Model 75.


This iconic aeroplane was the primary flight trainer for the United States military throughout the Second World War, and as a result was surplused in their thousands afterwards, becoming a firm favourite with crop dusters and stunt flyers. It is also the aircraft that Russel Casse saved the world with from an alien invasion – well, in the original cut at least.

But there was almost more to Stearman than just trainers. As they were achieving their success in building the Model 75 in the late 1930’s, Stearman decided to have a crack at winning a contract with the United States Army Air Corps (USAAC) that looked to be potentially highly profitable.

In 1938 the USAAC came to the realization that their latest light bomber, the Northrop A-17, was going to soon be obsolete, even though the aircraft had only been in service for a couple of years. Instead, the Air Corps determined that for their future requirements, attack bombers needed to be twin-engine designs.

A request was issued in March 1938 for a new aircraft to replace the A-17 that would have two engines and be capable of carrying a bombload of at least 1,200lb (c.545kg) at a speed greater than 200mph (322km/h). Contenders would have a year to build a prototype for demonstration – which they had to pay for themselves – and in response three of the biggest military aircraft builders in the United States made submissions…and Stearman, who entered this:

The Stearman X-100.

Now, to be fair, Stearman wasn’t quite the minor company that I am painting it out to be, because it was at the time a bit a strange organism, corporately speaking. Stearman was from 1934 to 1941 notionally a semi-independent entity, though in fact they were a part of Boeing, technically.

It all had to do with anti-trust cases that had occurred in the early 1930s, but essentially, at the time of the request issuing, Stearman was their own company, but also part of Boeing.

Anyway, the X-100 was a three-seat high-winged monoplane. It was, in fact, both the first monoplane AND all metal aircraft built by Stearman.

The X-100 also had a somewhat unusual crew area layout, being fitted with a large “greenhouse” style canopy. This housed the pilot and the bombardier and was built with the thinking that it would improve the aircraft’s streamlining in contrast to the standard “stepped” nose configuration used by many other contemporary aircraft of the time.

The third crew member, the radio operator/rear-gunner, sat in a position towards the rear of the aircraft where he was expected to man four separate defensive machine gun positions; a dorsal turret, one machine gun located in each waist position and a socket-mounted weapon in a ventral location.


In addition to this the aircraft boasted another .30-calibre machine gun in the nose, to be operated by the bombardier, and four of the same fixed forward firing in the wings for the pilot to use. Bombload was rated at 2,700lb (1,225kg) which handsomely exceeded the requirement, and range with a load of 1,200lb was recorded as 720 miles (c.1,160km).

To further improve streamlining the X-100 was given a retracting undercarriage, including the tail wheel. In addition, the X-100 also featured watertight compartments in the wings and fuselage that were designed to keep the aircraft afloat in the event of it having to ditch in water.

Powerplant was two Pratt & Whitney R-2180 Twin Hornet engines, which was something of a gamble as these were a new development that had only first run in 1936.


But they produced a maximum of 1,400hp each on take-off, more than most contemporary engines available at the time, and with them the X-100 recorded a top speed of 257mph (414km/h).


However, the flight testing revealed that the canopy layout was, somewhat ironically, an impediment to the pilot’s vision, with the bombardier’s position obstructing his view. So Stearman made a rapid change and switched the nose configuration to a more common “stepped” type as was more usual on aircraft of the type at the time.

And as it was, come the time to submit their designs, Stearman was one of only two aircraft available for testing by the Army, who subsequently designated the aircraft as the XA-21. Of their rivals, both the North American NA-40 and the Douglas Model 7B had crashed during their test programs leaving only the Martin Model 167 as competition to the Stearman aircraft.


This, designated as the XA-22, had less powerful engines and carried less than half the bombload of the XA-21, though it was faster.

So in theory, the XA-21 was a strong contender to be the United States next new attack aircraft. But this, as I am sure you are aware, did not occur.

Aircraft performance – even just between 1938 and ’39 – was really beginning to take off (if you’ll excuse the pun). Even as their deadline of March 1939 approached, the USAAC was rethinking their requirements, and as the date arrived decided that – actually – what they wanted was an aircraft capable of carrying 2,400lb (1,100 kg) of bombs over 1,200 miles (1,900 km) at 300 mph (480 km/h).

This benefitted Douglas and North American who, because of the loss of their original proposals, were able to come up with revised offerings that better suited the new requirements.

Douglas actually won and their DB-7 design would be adopted by the United States as the A-20 Havoc.


This would see copious amounts of service throughout the Second World War with a host of nations, with just under seven-and-a-half thousand being built.

North American’s new aircraft was ultimately to become the B-25 Mitchell, which was even more successful than the A-20! Nearly ten thousand of these would be built and it was arguably the most successful – and famous -US medium bomber of the war.

Martin were apparently pretty annoyed at Douglas winning. However, they had already won a contract from the French for their Model 167, which was ironically much larger than the initial contract that the USAAC signed for the Havoc and which was quickly followed by orders for the type from the British.


In total the French would receive just over two hundred of the aircraft they ordered from Martin, and they would see use fighting the German invasion in June 1940.

The outstanding balance of their aircraft would be handed over to British, who named them as the Martin Maryland and employed around two hundred of them in total. Due to their good speed the RAF mainly deployed them for reconnaissance, and it was one of these Maryland’s that first reported the departure of the German battleship Bismark that ultimately led to that ships doom.

A final claim to fame for the type is that after the fall of France a number of the Martin bombers remained in service with the Vichy regime in North Africa, and as such saw action against Allied troops there, making it one of the few types to fight on both sides.

The comparatively large purchase of all these aircraft by foreign customers allowed Martin to expand their production facilities, which led to the development of the Martin Baltimore, which was an important type with the RAF and Commonwealth air forces, and then the B-26 – another iconic aircraft of the War.

So, it seems a bit odd that with all the orders flying around that the Stearman XA-21 just…disappeared. I mean literally. No one seems to know what happened to the one aircraft built.

It seems that the USAAC conducted some more testing with it and then scrapped it.

But it is strange. On paper certainly it was a competent enough aircraft, plus it had the advantage of not actually crashing during its development. If it had some terrible defect that made it an obvious lemon that no one would touch, I am sure that some record of that fact would exist. After all, the issue with the canopy was noted and rectified in short order.

But there seems to be no clue as to why the XA-21 just vanished.

Considering that at the time many countries were desperately buying up anything they could get their hands on, including plenty of designs that would work out to be pretty mediocre, it seems surprising that Stearman didn’t pitch the XA-21 to at least some potential foreign clients. The aircraft may not have been outstanding, but it was certainly on par with many other aircraft of the time.

And if you are hoping I have answers, I am afraid I don’t. If I was to speculate, it’s maybe because that about this time Boeing started making moves to integrate Stearman fully back into the group properly. In fact, by 1941 Stearman Aircraft ceased to exist and they became the Wichita Division of Boeing.

So maybe Boeing didn’t want Stearman chasing big ticket contracts and reinforcing their independence while they worked out this integration?

As said, I am wildly speculating here, and if anyone knows the reality, please feel free to tell us all in the comments.

But as for the XA-21, well, as said it just disappeared into history. But considering the evolution and success of the other designs that it competed against, it certainly is an intriguing forgotten aircraft.


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