From Joe Baugher:

Douglas A-26B Invader

The A-26B was the solid-nosed attack version of the Invader. The XA-26B-DE (41-19588) was the prototype of this particular version and was fitted with an unglazed nose housing a forward-firing 75-mm cannon. The crew consisted of pilot and gun loader/navigator seated side-by-side in the forward cockpit, and a gunner in the rear position behind the wing trailing edge. In addition, there was a “jump” seat behind the loader/navigator’s position that could be used by an extra person who was going along for a ride. The rear gunner was provided with two viewing windows, one in the dorsal position and the other in the ventral position, and he aimed the guns remotely via an optical sighting system.

It turned out that the XA-26B was the last Invader to be built at the El Segundo plant. Plans were for the production version of the Invader to be built at newly-constructed Douglas plants in Tulsa, Oklahoma and in Long Beach, California. It was planned that the solid-nosed B would be manufactured side-by side with the transparent-nosed C at both plants.

The production of the Invader began first at the Long Beach plant. The solid-nosed B was actually the first off the production line. The first of five A-26B-1-DL Invaders appeared in September of 1943. As compared with the prototype, the A-26B had an increased bomb load (6000 pounds) and higher internal fuel capacity of 1600 US gallons. The powerplants were housed in slightly revised nacelles and drove three-bladed propellers without spinners. The engines were a pair of 2000 hp Pratt & Whitney R-2800-27 radials.

Fifteen A-26B-5s followed with minor changes and which eliminated the camouflage that had been previously applied to bombers. These versions had one 75-mm cannon in the nose and two 0.50-inch machine guns on the left side.

A new all-purpose nose was installed beginning with the A-26B-10-DL. Initially, the USAAF was undecided about exactly what armament this version should carry. As originally planned, it was expected that the A-26B would be fitted with a variety of alternate solid nose sections, and that one deemed to the best would be selected. Options that were tested on early A-26Bs included one 75-mm cannon to starboard and two 0.50-inch machine guns to port, one 75-mm cannon to starboard and one 37-mm cannon to port, 2 37-mm cannon with one on each side of the nose, or one 37 mm cannon to starboard and two 0.50-inch machine guns to port; four 0.50-inch guns starboard and one 37-mm cannon to port; or four 0.50-inch guns to starboard and two 0.50-in guns to port. Eventually at the end of 1944, the USAAF finally made up its mind and decided that the solid-nosed A-26B would have six machine guns. with 400 rounds per gun. The guns in the two turrets had 500 rounds each.

Beginning with the A-26B-15, the forward-firing armament could be supplemented by eight 0.50-inch guns mounted in four twin packages underneath the outer wing panels.

Five aircraft from the initial Fiscal Year 1941 A-26 production batch were completed as A-26C-DL bombers with transparent noses and two nose guns. These were destined to be the only A-26Cs to be built at Long Beach, all the remaining A-26Cs being built at Tulsa.

The first 500 Invaders (up to A-26B-40-DL) were built at Long Beach. A parallel production line was established at Tulsa, Oklahoma for 500 aircraft ordered on March 17, 1943. The first Tulsa-built A-26Bs appeared in January of 1944. Of the Tulsa-built Invaders, 205 were delivered as A-26Bs with the rest being built as A-26Cs with glazed noses. Most of these Tulsa-built A-26Bs were powered by the Ford-built R-2800-71 engine with a revised ignition system.

Although both the Long Beach and Tulsa plants had started building both Invader versions, it was decided in late 1944 that this was an inefficient arrangement and that it would make better sense for the Long Beach plant to build only A-26Bs and the Tulsa plant to build only A-26Cs. This was indeed done, and the Long Beach plant stopped producing A-26Cs after only five were built.

During production, a number of improvements were introduced on the line. The oil cooler inlets on the wing leading edge were redesigned. The dorsal turret was modified to eliminate empennage buffeting. Initial combat reports from the field had complained about poor visibility from the cockpit, especially to the side. In order to improve visibility, the original flat-topped cockpit canopy which opened upward on the right side of the cockpit was replaced by a raised canopy opening in clamshell-fashion in two separate frameless transparent elements hinged at the sides of the fuselage. The canopy was a bit narrower on the pilot’s side of the aircraft than it was on the copilot’s. The new canopy enabled the pilot to see over both engine nacelles and towards the tail surfaces and it made it possible for him to check whether both main landing wheels were down. This new canopy was at first hand-built and fitted to a few early aircraft, but was introduced as standard equipment beginning with the A-26B-30-DL block.

Beginning with the A-26B-45-DL block, the engines were switched to Ford-built R-2800-79 with water injection, raising the war emergency power to 2350 hp.

The forward-firing armament of the early A-26B was found to be insufficient, especially in the Pacific theatre. Beginning with the A-26B-50-DL production block, a new eight-gun nose was fitted, and six internally-mounted 0.50-inch guns were mounted in the outer wing panels so that bombs or rockets could be carried underneath the wings. However, the eight-gun nose and the internal wing guns were often retrofitted to earlier A-26B versions, so the mere presence of these features cannot be used as a positive identification feature.

In aircraft destined for service in the Pacific (-51-DL, -56-DL, -61-DL, and -66-DL), the remotely-controlled ventral turret was replaced by a 125-US gallon auxiliary tank for extra range.

A total of 1150 A-26Bs were built at Long Beach (A-26B-1-DL to A-26B-66-DL) and an additional 205 were built at Tulsa (A-26B-5-DT to A-26B-25-DT). Production of the A-26B ended at Long Beach in September 1945, when the end of the war resulted in the cancellation of further contracts. Production of the B at Tulsa had ceased at the end of 1944 at Tulsa, when the decision was made that the Oklahoma plant would concentrate solely on the transparent-nosed A-26C version.

In June of 1948, the A-26B was re-designated B-26B. There was no danger of confusion with the Martin B-26 Marauder, since that aircraft was by that time out of service.

A lot of people have asked how the crew got in and out of the plane. Here’s how ex-Invader pilot Bob McFarland describes it. There was a spring-loaded one-rung ladder on the right side of the fuselage just in front of the wing. On the side of the fuselage there were a series of spring-loaded covered slots for feet and hands. The entering crewman would pull down the ladder and use the slots to crawl up the side of the plane to the top of the fuselage. Once on top, the entrance to the cockpit was made through the open clamshell doors. By all accounts, the entry into the cockpit was tricky and took a bit of getting used to. Once inside the cockpit, the fastening of the canopy was a difficult operation, and there were occasions when it wasn’t fastened properly and flew open in flight. The rear gunner crawled up the side of the aircraft in the the same way the pilot and navigator did, but once on top of the fuselage he would have to crawl to the rear and wend his way over the dorsal turret, open a hatch in the transparent upper cover and enter his compartment.

If it became necessary to bail out in the event of an inflight emergency, both of the clamshell canopy doors would be jettisoned and the pilot and navigator would crawl out on the right side of the aircraft and exit over the wing (the leading edge of the wing was just aft of the rear of the clamshell door) and hope that they weren’t hit by the horizontal stabilizer. The pilot went out the right side as well, since it was difficult for him to exit on the left, because the clamshell door was considerably shorter on that side and stopped well short of the leading edge of the wing. The gunner would exit the aircraft via the same hatch he used to enter.

Serials of A-26B:

41-19588                Douglas XA-26B-DE Invader 	c/n 1006
41-39100/39104		Douglas A-26B-1-DL Invader 	c/n 6813/6817
41-39105/39119		Douglas A-26B-5-DL Invader 	c/n 6818/6832
41-39120/39139		Douglas A-26B-10-DL Invader 	c/n 6833/6852
41-39140/39151		Douglas A-26B-15-DL Invader	c/n 6853/6864
41-39153/39192		Douglas A-26B-15-DL Invader	c/n 6866/6905
41-39194		Douglas A-26B-15-DL Invader     c/n 6907
41-39196/39198		Douglas A-26B-15-DL Invader    	c/n 6909/6911
41-39201/39299		Douglas A-26B-20-DL Invader     c/n 6914/7012
41-39300/39349		Douglas A-26B-25-DL Invader     c/n 7013/7062
41-39350/39424		Douglas A-26B-30-DL Invader     c/n 7063/7137
41-39425/39499		Douglas A-26B-35-DL Invader     c/n 7138/7212
41-39500/39599		Douglas A-26B-40-DL Invader     c/n 7213/7312
43-22252/22266		Douglas A-26B-5-DT Invader      c/n 18399/18413
43-22267/22301		Douglas A-26B-10-DT Invader     c/n 18414/18448
43-22302/22303		Douglas A-26B-16-DT Invader     c/n 18449/18450
43-22305/22307		Douglas A-26B-15-DT Invader     c/n 18452/18454
43-22313/22345		Douglas A-26B-15-DT Invader     c/n 18460/18492
43-22350/22399		Douglas A-26B-15-DT Invader     c/n 18497/18546
43-22400/22453		Douglas A-26B-20-DT Invader     c/n 18457/18600
43-22454/22466		Douglas A-26B-25-DT Invader     c/n 18601/18613
44-34098/34217		Douglas A-26B-45-DL Invader     c/n 27377/27496
44-34218/34286		Douglas A-26B-50-DL Invader     c/n 27497/27565
44-34287		Douglas A-26B-51-DL Invader     c/n 27566
44-34288/34296		Douglas A-26B-50-DL Invader     c/n 27567/27575
44-34297/34298		Douglas A-26B-51-DL Invader     c/n 27576/27577
44-34299/34322		Douglas A-26B-50-DL Invader     c/n 27578/27601
44-34323		Douglas A-26B-51-DL Invader     c/n 27602
44-34324/34326		Douglas A-26B-50-DL Invader     c/n 27603/27605
44-34327		Douglas A-26B-51-DL Invader     c/n 27606
44-34328/34330		Douglas A-26B-50-DL Invader     c/n 27607/27609
44-34331		Douglas A-26B-51-DL Invader     c/n 27610
44-34332		Douglas A-26B-50-DL Invader	c/n 27611 
44-34333/34334		Douglas A-26B-55-DL Invader	c/n 27612/27613
44-34335		Douglas A-26B-56-DL Invader	c/n 27614
44-34336/34338		Douglas A-26B-55-DL Invader	c/n 27615/27617
44-34339		Douglas A-26B-56-DL Invader	c/n 27618
44-34340/34342		Douglas A-26B-55-DL Invader	c/n 27619/27621
44-34343		Douglas A-26B-56-DL Invader	c/n 27622
44-34344/34346		Douglas A-26B-55-DL Invader	c/n 27623/27625
44-34347		Douglas A-26B-56-DL Invader	c/n 27626
44-34348/34350		Douglas A-26B-55-DL Invader	c/n 27627/27629
44-34351		Douglas A-26B-56-DL Invader	c/n 27630
44-34352/34363		Douglas A-26B-55-DL Invader	c/n 27631/27642
44-34364		Douglas A-26B-56-DL Invader	c/n 27643
44-34365/34367		Douglas A-26B-55-DL Invader	c/n 27644/27646
44-34368		Douglas A-26B-56-DL Invader	c/n 27647	
44-34369/34371		Douglas A-26B-55-DL Invader	c/n 27648/27650
44-34372		Douglas A-26B-56-DL Invader	c/n 27651
44-34373/34376		Douglas A-26B-55-DL Invader	c/n 27652/27655
44-34377		Douglas A-26B-56-DL Invader	c/n 27656
44-34378/34381		Douglas A-26B-55-DL Invader	c/n 27657/27660
44-34382		Douglas A-26B-56-DL Invader	c/n 27661
44-34383/34386		Douglas A-26B-55-DL Invader	c/n 27662/27665
44-34387		Douglas A-26B-56-DL Invader	c/n 27666
44-34388/34392		Douglas A-26B-55-DL Invader	c/n 27667/27671
44-34393		Douglas A-26B-56-DL Invader	c/n 27672
44-34394/34398		Douglas A-26B-55-DL Invader	c/n 27673/27677
44-34399		Douglas A-26B-56-DL Invader	c/n 27678
44-34400/34404		Douglas A-26B-55-DL Invader	c/n 27679/27683
44-34405		Douglas A-26B-56-DL Invader	c/n 27684
44-34406/34408		Douglas A-26B-55-DL Invader	c/n 27685/27687
44-34409		Douglas A-26B-56-DL Invader	c/n 27688
44-34410/34412		Douglas A-26B-55-DL Invader	c/n 27689/27691
44-34413		Douglas A-26B-56-DL Invader	c/n 27692
44-34414/34416		Douglas A-26B-55-DL Invader	c/n 27693/27695
44-34417		Douglas A-26B-56-DL Invader	c/n 27696
44-34418/34419		Douglas A-26B-55-DL Invader	c/n 27697/27698
44-34420		Douglas A-26B-56-DL Invader	c/n 27699
44-34421/34422		Douglas A-26B-55-DL Invader	c/n 27700/27701
44-34423		Douglas A-26B-56-DL Invader	c/n 27702
44-34424/34472		Douglas A-26B-55-DL Invader	c/n 27703/27751
44-34473/34477		Douglas A-26B-60-DL Invader	c/n 27752/27756
44-34478		Douglas A-26B-61-DL Invader	c/n 27757
44-34479/34480		Douglas A-26B-60-DL Invader	c/n 27758/27759
44-34481		Douglas A-26B-61-DL Invader	c/n 27760
44-34482/34483		Douglas A-26B-60-DL Invader	c/n 27761/27762
44-34484		Douglas A-26B-61-DL Invader	c/n 27763
44-34485/34486		Douglas A-26B-60-DL Invader	c/n 27764/27765
44-34487		Douglas A-26B-61-DL Invader	c/n 27766
44-34488/34489		Douglas A-26B-60-DL Invader	c/n 27767/27768
44-34490		Douglas A-26B-61-DL Invader	c/n 27769
44-34491/34492		Douglas A-26B-60-DL Invader	c/n 27770/27771
44-34493		Douglas A-26B-61-DL Invader	c/n 27772
44-34494/34495		Douglas A-26B-60-DL Invader	c/n 27773/27774
44-34496		Douglas A-26B-61-DL Invader	c/n 27775
44-34497/34498		Douglas A-26B-60-DL Invader	c/n 27776/27777
44-34499		Douglas A-26B-61-DL Invader	c/n 27778
44-34500/34501		Douglas A-26B-60-DL Invader	c/n 27779/27780
44-34502		Douglas A-26B-61-DL Invader	c/n 27781
44-34503/34504		Douglas A-26B-60-DL Invader	c/n 27782/27783
44-34505		Douglas A-26B-61-DL Invader	c/n 27784
44-34506/34507		Douglas A-26B-60-DL Invader	c/n 27785/27786
44-34508		Douglas A-26B-61-DL Invader	c/n 27787
44-34509/34510		Douglas A-26B-60-DL Invader	c/n 27788/27789
44-34511		Douglas A-26B-61-DL Invader	c/n 27790
44-34512/34513		Douglas A-26B-60-DL Invader	c/n 27791/27792
44-34514		Douglas A-26B-61-DL Invader	c/n 27793
44-34515/34516		Douglas A-26B-60-DL Invader	c/n 27794/27795
44-34517		Douglas A-26B-61-DL Invader	c/n 27796
44-34518/34519		Douglas A-26B-60-DL Invader	c/n 27797/27798
44-34520		Douglas A-26B-61-DL Invader	c/n 27799
44-34521		Douglas A-26B-60-DL Invader	c/n 27800
44-34522/34585		Douglas A-26B-61-DL Invader	c/n 27801/27864
44-34586		Douglas XA-26F-DL Invader	c/n 27665
44-34587/34617		Douglas A-26B-61-DL Invader	c/n 27866/27896			
44-34618/34753		Douglas A-26B-66-DL Invader	c/n 27897/28032

Specification of Douglas A-26B-15-DL Invader:

Engines: Two Pratt & Whitney R-2800-27 or -71 air-cooled radials, each rated at 2000 hp for takeoff and 1600 hp at 13,500 feet. Performance: Maximum speed 355 mph at 15,000 feet. Cruising speed 284 mph. An altitude of 10,000 feet could be attained in 8.1 minutes. Service ceiling 22,100 feet. Normal range 1400 miles, Maximum range 3200 miles. Dimensions: Wingspan 70 feet 0 inches, length 50 feet 0 inches, height 18 feet 6 inches, wing area 540 square feet. Weights: 22,370 pounds empty, 27,600 pounds loaded, 35,000 pounds maximum. Armament: Six forward-firing 0.50-inch machine guns in nose. Forward-firing armament could be supplemented by eight 0.50-inch guns mounted in four-gun twin packages mounted underneath the outer wing panels. Two 0.50-inch machine guns in remotely-controlled dorsal turret. Two 0.50-inch machine guns in remotely-controlled ventral turret. An internal bomb load of 4000 pounds could be carried Maximum total bomb load of 6000 pounds.

Specification of Douglas A-26B-60-DL Invader:

Engines: Two Pratt & Whitney R-2800-79 air-cooled radials, each rated at 2000 hp for takeoff, 2350 hp with water injection. Performance: Maximum speed 355 mph at 15,000 feet. Cruising speed 284 mph. An altitude of 10,000 feet could be attained in 8.1 minutes. Service ceiling 22,100 feet. Normal range 1400 miles, Maximum range 3200 miles. Dimensions: Wingspan 70 feet 0 inches, length 50 feet 8 inches, height 18 feet 6 inches, wing area 540 square feet. Weights: 22,362 pounds empty, 26,000 pounds loaded, 41,800 pounds maximum. Armament: Eight forward-firing 0.50-inch machine guns in nose. Three 0.50-inch machine guns mounted in each of the outer wing panels. Two 0.50-inch machine guns in remotely-controlled dorsal turret. Two 0.50-inch machine guns in remotely-controlled ventral turret. An internal bomb load of 4000 pounds could be carried. Maximum total bomb load of 6000 pounds.

Sources:

United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian Institution Press, 1989.
McDonnell Douglas Aircraft Since 1920: Volume I, Rene J. Francillon, Naval Institute Press, 1988.
American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.
E-mail from Bob McFarland on entrance and exit from the A-26.