Douglas A/B-26 Invader

In-Depth Analysis

HOME | SUB INDEX | Preface | Features | Site Navigation | Reg'n cross ref. | S/No's & Prod'n codes | MILITARY VARIANTS - History, Data & Photos | CIVIL VARIANTS - History, Data & Photos | About the author/Contact | Info Req'd | LATEST


In depth analysis

Given the designation XA-26, the contract specified for Douglas to build one XA-26 attack aircraft and one XA-26A night fighter. The estimated price of the development, tooling, and construction of these aircraft was $2,083,385.79 with an additional fee of $125,000. Initially, Douglas submitted a fixed-fee proposal but the final document became a cost plus fixed-fee contract which gave the company a bit more latitude.

Soon after the original contract was assigned, it was amended to include a third airframe - the XA-26B which would mount the 75mm cannon. Army bean counters were soon complaining about the costs of the Douglas aircraft on a cost-per-pound basis: "A comparison of prices indicated that the price-per pound of the XA-26 was greater than any other experimental model. The price-per-pound of the XA-26 and XA26A aircraft was partially justified by the fact that the XA-26A was radically different from the XA-26 so that Douglas was, in effect, quoting on design and construction of two different aircraft." This was just the start of the troubles that were to beset the new aircraft.

Douglas went ahead with the prototypes - the two attack aircraft would have three crewmen while the night fighter would have two. As work proceeded on the new aircraft, the Army increased contractual commitments to a whopping 500 A-26s during October 1941. Douglas stated these aircraft could be delivered to the military at a cost of $142,250 per machine and proposed that the planes be built at their Clover Field facility in Santa Monica. The Army and Douglas once again started to haggle about prices and the Army did not think the Clover facility had enough capacity since it was already building a number of other designs. An agreement would once again be reached but there were changes - the A-26s would now be built at new factories constructed by Douglas and the government in Long Beach, California, and Tulsa, Oklahoma.

Unfortunately, difficulties between Douglas, the War Department, and the Army resulted in more delays with both sides blaming each other. Each was probably somewhat responsible. For example, the Army could not decide how they would mix the order - changing their minds several times. In July 1942, Douglas was ordered to build all 500 aircraft with the 75mm cannon nose but this was again soon changed. Douglas then had to design a new nose armament when the military decided to proceed with the 75mm cannon. At the same time, the Army was considering further variants with four 37mm cannon and a recon version with cameras and extra fuel tanks.

For extra strength and some weight saving, Douglas would be using the new 75S aluminium alloy. Milling machines were to be used to make the aircraft's components easier to build while also allowing for the extremely precise tolerances needed for things such as the laminar flow wing. However, initial shortages of milling machines soon set the program back.

By the time of the Japanese sneak attack on Pearl Harbour, Douglas was busy working on a new all-purpose gun nose that could hold a variety of weapons and would be convertible in the field to change the weapons to fit the mission. This was heavy-duty work since a lot of different brackets and equipment had to be crammed into the nose to accommodate the Army. Work on this nose continued well into 1942 and various armament packages included two 37mm cannon, one 75mm cannon and two .50-caliber machine guns, four .50-calibers and one 37mm, and six .50-caliber weapons.

While all this change was going on, famed pre-war racing pilot and designer Benny Howard, took the XA-26 prototype aloft for a relatively trouble-free flight from Mines Field (now LAX) on 10 July 1942. This date was a problem in itself, since Douglas had told the Army that the aircraft would make its first flight on 15 January - a delay of almost six months. Some cooling problems with the R-2800s were encountered - this was rectified by a cowling modification and removal of the large but elegant spinners that tightly fit around the air opening (however, these spinners were apparently built in quantity before cancellation and would reappear on various Douglas test aircraft). The prototype was originally flown with a glass nose and armament was not carried although turret domes were installed. As flight testing progressed, the armament would be installed and consisted of two .50-calibers on the right side of the nose in a fixed position along with two .50s in the upper and lower turret. Normally operated by the gunner with his periscope controls, these turrets could both be locked in the forward position and fired by the pilot. The XA-26 could handle up to 3000 pounds of bombs in the two fuselage bays while a further 2000 pounds of bombs could be held on under wing pylons. There was also provision to carry two torpedoes in the bomb bay although this does not appear to have ever been done outside possible test applications even though torpedo operations were included in A-26 pilot manuals well into the late 1940s.

The flight test program was joined by the XA-26A. This was the night fighter variant and it was a mean-looking aircraft with a solid nose which housed the MIT AI-4 centimetric radar while a large "tray" under what had been the forward bomb bay held four fixed 20mm cannon with the ammunition being carried in the bomb bay. The surviving rear bay could also handle up to 2000 pounds of bombs for intruder missions. Also, a dorsal turret was retained but modified to handle four .50-caliber Brownings. This was an extremely potent weapons package but it was decided to standardize on the

The third prototype, and last A-26 built at El Segundo, was the XA-26B which had a solid nose fitted with the massive 75mm cannon. Over the course of testing, this nose was modified several times to accommodate changes in the mounting of the 75mm weapon and the addition of a 37mm cannon.

There were problems with late delivery of components from outside manufacturers while the government itself was having difficulties supplying government-furnished equipment (GFE) such as propellers and engines. Also, production tooling was well behind schedule and the non-standard prototype tooling was transferred to the production line so the first six production A-26s were built with this equipment.

Problems were also becoming apparent with the wing. The A-26 wing was built around eight inboard and eight outboard spars. Each outboard spar was different from its fellow and required a special manufacturing arrangement. The lack of milling machines was a major problem and General Oliver Echols who was attempting to rectify A-26 production problems started giving consideration to using milling machines held by various Boeing production plants until, as he stated, "such time as the machines ordered for the A-26 program are delivered." Sub-contractor Beech Aircraft, who was to make the spars for the A-26s being built at Tulsa, was also awaiting its milling machines.

Problems continued and in a damning indictment for both company and military, it was not until the end of 1944 that the decision was made that the Long Beach plant would produce A-26Bs with a solid nose containing either six or eight machine guns while the Tulsa facility would discontinue building A-26Bs in favour of glass nose A-26Cs. All the while there was a war going on and the aircraft were sorely needed at the combat fronts. During this time, plans for 37mm and 75mm variants joined the night fighter in the heap of discarded A-26 ideas.

It took a stunning 28 months to get the Invader, as the type had now been named, from flight test to combat deployment.

Douglas did manage to sort out many of the problems and went on to build 2400 Invaders in the last 20 months of the Second World War. All these problems led General Henry "Hap" Arnold to scathingly record, "We cannot have more A-26s although we have plenty of fuselages, but not enough wings. We could build more wings if we had more spars, but we cannot build more spars due to difficult output of machinery. We might be able to build more wings if we were able to get more machinery, but whether we will be able to get more machinery I was unable to determine and nobody could give me the answer. One thing is certain: I want the A-26 for use in this war and not for the next war. If something drastic is not done, we cannot hope to replace the B-25s, B-26s, and A-20s with the A-26."

Although the Invader looked pretty much the same throughout its production life, the aircraft was beset by hundreds of changes - as many as 35 a day which really delayed production. Even worse was to come when an A-26 wing failed during a static test in May 1944. The Army demanded that Douglas redesign the wing and incorporate a ten percent increase in strength. This was done but seven more wing failures were recorded before another Army demand for redesign. In service, many pilots handled the Invader as if it was a fighter. With performance similar to many fighters, the aircraft was not as strongly built but many pilots remember seven to eight G manoeuvres while attacking the enemy. Even today, close inspection of the wing and care in handling the aircraft during manoeuvring are undertaken to avoid overstress on the wing. Another problem that remained through the Invader's considerable life span is that of a somewhat weak nose gear. On landing, some pilots would use back pressure on the control column to hold the nose gear off for as long as possible. However, this could actually cause an oscillation in the aircraft that would result in the nose gear slamming down hard on the runway. Douglas advised against this procedure and, in a normal landing, the nose gear would touch down just a second or two after the mains. This is standard operation on today's Invader War birds.

Changes were also coming in from the combat fronts. Four early production aircraft were rushed to the Fifth Air Force during mid-1944 for combat testing with the 13th Bombardment Squadron, 3rd Bombardment Group, in New Guinea. The pilots flying the aircraft (A-26B-5-DLs) really liked the A26's high speed and response to throttle settings but when the under wing .50caliber gun packs were added, they were a bit dismayed by a 25 mph drop in speed due to the extra drag. Also, in the Pacific environment, they found that the bottom turret was unnecessary. Maintenance personnel found the easily removable panels that Douglas had designed into the Invader really helped during in-field maintenance but the hot and humid climate did cause trouble with fuel selector values, air filters, and the electrical system.

However, the biggest complaint was with the canopies. As can be seen in the photographs, these were individual units that were hinged to open to the front but they were also fairly flat and confining for the crew, Visibility was less than adequate given those big nacelles on either side of the cockpit and the pilots found that when flying a low, line-abreast formation (common in the Pacific for attacking and strafing Japanese airfields and facilities), it was very hard to see aircraft to either side. Also, pilots felt that the elevator forces were too heavy during high speed, low-- level pullouts and they also thought that the location of the life raft was poor in the event of a ditching.

Back in southern California, Douglas engineers rapidly went to work on these problems and created a bulged canopy that opened to each side of the fuselage and greatly increased visibility. In the fall of 1944, the commander of the Third Bomb Group flew the first aircraft with the bulged canopy and was delighted with the results. At the factories, problems producing the Invader were still continuing, leading General George Kenney, Far East Air Forces commander, to state, "We do not want the A-26 under any circumstances as a replacement for anything." But it must be remembered that many of these problems and delays could be directly blamed upon the military for their many changes while trying to decide on the aircraft's armament. It should also be noted that Douglas managed to sort out many of these problems and built 2400 Invaders during the last 20 months of the Second World War. As time went on, the Army cancelled requirements for the 37mm weapons and then the 75mm cannon was also dropped - tens of thousands of design and production man-hours went down the drain. Armament was standardized on six- or eight-gun hard noses for the A-26B and a glass nose with two side-mounted .50-caliber guns for the A-26C (although many aircraft did not have these weapons). Also, the Invader could also carry a further six .50 calibers internally in the wing or eight .50 calibers in four under wing pods. Hardnose variants could boast the incredibly destructive forward firepower of 20 .50-caliber machine guns. The Invader was starting to come into its own. General Kenney even revised his opinions regarding the Invader and recorded, "The version with the eight-gun nose and no bottom turret had proven to be highly satisfactory as a replacement for A-20s and B-25s (in the Pacific and Far East)."

In Europe, Major General Hoyt Vandenberg was supporting the decision to have the Invader replace the Marauder and Havoc. The Ninth Air Force's 553rd Bomb Squadron, 386th Bomb Group, took the Invader into combat over Occupied Europe during September 1944 but the pilots had a hard time finding enough targets to attack at low-level with the aircraft's massive firepower. The 553rd operated 18 Invaders during eight test combat missions. With these eight missions, the Army Air Force stated that, "it was concluded that the A-26 was a very effective medium bomber with a larger load than the A-20, greater range than either the A-20 or B-26, and with superior single-engine performance. Its speed advantage, flying characteristics, manoeuvrability, and ease of maintaining formation permitted longer missions with less crew fatigue. On the missions flown, gasoline consumption was lower and radius of action was greater than had been expected."

Towards the end of 1944, the AAF formulated its plans for the Invader. In Europe, all A-20 groups and all but three Marauder groups would have their aircraft replaced with Invaders - this to take place by mid1945, letting the AAF field eleven Invader groups. In the Pacific, there was still opposition to the Invader based on the somewhat negative experience with the four early test aircraft but the AAF wanted to replace Mitchells with Invaders in all theatres as soon as adequate airframes were available. The AAF order of conversion with the A-26 was set in the following priority: 1) European Theatre; 2) Mediterranean Theatre; 3) China-- Burma-India Theatre; 4) AAF-POA; 5) Far East Air Forces; 6) Northern Pacific.

With constantly changing war situations, by April 1945 the AAF issued an order that A-26s were to be produced in a ratio of two-thirds gun noses to one-third bombardier noses. It must also be remembered that these noses were interchangeable in a fairly easy manner and noses were often switched depending on mission. Some historians state that if an A-26B was equipped with a C nose, then it should be referred to as an A-26C and vice versa if the hard nose was installed on an A-26C. However, I think the more logical choice is to go with what the name plate in the cockpit states.

As more Invaders flowed from the factories to the combat fronts, it soon became evident that the Invader was an outstanding aircraft. With its high speed, heavy weapon load, and excellent manoeuvrability, the Invader would often fight it out with the best of Axis fighters. If the A-26 had been available earlier in the war, it would have made a difference.

With the defeat of the Nazis, America deployed more forces to the deadly battles heading towards the Home Islands of Japan. It was planned to deploy seven Invader groups (including a Pathfinder group). All medium bomber groups were to have their aircraft replaced with Invaders except for a trio of Mitchell units operating with the FEAR Also, a decision was made not to supply Invaders to friendly nations under Lend-Lease (presumably, this was so the Soviets would not get the type). Plans were also made to replace all Marauders with Invaders as the war entered 1946 - the creation of the atomic bomb was only known to a few.

With American and the Allies steamrollering across the Pacific towards Japan, cutbacks were made in Invader contracts and production was reduced to 150 aircraft per month. It is interesting to note the learning curve in A-26 production as reflected by costs. In 1943, the average Invader cost $254,624. In 1944, cost had dropped to $192,457. By the conclusion of production in 1945, the government was being charged $116,752.

By mid-1945, weapons were pouring from American factories at an unprecedented rate and it was decided to stop Tulsa Invader production during June of that year, after the factory had delivered 1753 examples. Preparations for the massive invasion of Japan were suddenly moot when atomic bombs were dropped on Hiroshima and Nagasaki. American war material factories were hit with massive contract cancellations and A-26 contracts at Long Beach were suspended on 17 August 1945.