The Douglas A-26 Invader, previously designated B-26 from 1948 to 1965, was a twin-engine American light bomber and ground attack aircraft.
It was manufactured by the Douglas Aircraft Company during World War II and was also utilized during multiple Cold War conflicts.
A limited number of modified aircraft from the United States Air Force were deployed in Southeast Asia until 1969.
The Invader was a speedy plane that could carry a considerable bomb load.
Additionally, a variety of guns could be equipped to create a powerful ground-attack aircraft.
However, the redesignation of the A-26 to B-26 caused confusion with the Martin B-26 Marauder, which made its first flight in November 1940, 20 months prior to the maiden flight of the Douglas design.
Despite both aircraft being powered by the widely used Pratt & Whitney R-2800 Double Wasp 18-cylinder, double-row radial engine, they were entirely different and distinct designs.
The Marauder had a production of around 5,300 units, while the Invader had a production of approximately 2,503 units.
The A-26 was Douglas Aircraft’s successor to the A-20 (DB-7) Havoc, also known as Douglas Boston.
Designed by Ed Heinemann, Robert Donovan, and Ted R. Smith, the innovative NACA 65-215 laminar-flow airfoil wing of the A-26 was the work of project aerodynamicist A.M.O. Smith.
The Douglas XA-26 prototype (AAC Ser. No. 41-19504) first flew on 10 July 1942 at Mines Field, El Segundo, with test pilot Benny Howard at the controls.
Flight tests revealed excellent performance and handling, but engine-cooling problems led to cowling changes and elimination of the propeller spinners on production aircraft.
During testing, the nose wheel was found to be structurally inadequate, thus the nose gear was redesigned and made more structurally sound.
On May 5th, 1943, the Douglas XA-26B Invader AAF Ser. No. 41-19588 was built with a “strafer” nose that allowed for various weapon combinations, including a 75 mm (3 in) cannon.
The A-26 had two configurations: the A-26B gun-nose and the A-26C “glass” “Bombardier nose”. The former could be equipped with a range of armament, such as .50 calibre machine guns, 20 or 37mm autocannon, or a 75mm pack howitzer (which was never used operationally).
The ‘B’ gun-nose version was also known as the “all-purpose nose”, housing six (eight later) .50 calibre machine guns and was also referred to as the “six-gun nose” or “eight-gun nose”.
The A-26C “glass” “Bombardier nose” had a Norden bombsight for precision bombing at medium altitudes.
It initially included two fixed M-2 guns, but they were removed after underwing gun packs or internal guns in the wings proved effective in colder weather.
After producing around 1,570 aircraft, three guns were installed in each wing of the A-26B, coinciding with the “eight-gun nose” introduction, allowing for up to 14 .50 in (12.7 mm) machine guns in fixed forward mounts.
It was possible to replace an A-26C nose section with an A-26B nose section, or vice versa, in a few hours, which would change the operational role and designation of the aircraft.
In late 1944, the “flat-topped” canopy was replaced with a clamshell style, significantly improving visibility.
In an A-26B, a crew member would serve as a navigator and gun loader for the pilot-operated nose guns.
In an A-26C, that crew member would serve as a navigator and bombardier, relocating to the nose section for the bombing phase of the operation.
Some A-26Cs had dual flight controls, with parts that could be disabled in flight to provide access to the nose section.
The bombardier would sit next to the pilot and access the lower section of the right instrument panel.
Behind the navigator’s seat, there was a tractor-style “jump seat”.
Typically, a third crew member would operate the remote-controlled dorsal and ventral gun turrets in the rear gunner’s compartment. Access to and from the cockpit was only possible via the bomb bay if it was empty.
The gunner would operate both dorsal and ventral turrets with a complex dual-ended periscope sight, which proved problematic and difficult to maintain in the field.
The system computed for parallax and other factors, aiming the guns in the approximate direction of the periscope. Variants Douglas/U.S. Military Variants Many of the A-26/B-26 Invader’s production run of 2,452 were early A-26Bs and A-26Cs. XA-26 Serial no. 41-19504 served as the prototype for the series; initially flown with dummy armament. XA-26A Serial no. 41-19505 served as a prototype night fighter with a crew of two – pilot plus radar-operator/gunner. XA-26B Serial no. 41-19588 was a prototype “solid-nosed” attack variant with crew of three: pilot, gun loader/navigator (in front cockpit) plus gunner in rear and carrying a forward-firing 75 mm (2.75 in) cannon. A-26B Attack bomber with solid nose carrying six or eight 0.50 in (12.7 mm) machine guns. Production totals: 1,355 A-26Bs were built and delivered, 205 at Tulsa, Oklahoma (A-26B-5-DT to A-26B-25-DT) plus 1,150 at Long Beach, California (A-26B-1-DL to A-26B-66-DL). About 24 more airframes were built at Long Beach but not delivered to USAAF, some of those later sold to other civil and military customers. A-26B was redesignated B-26B with USAF in 1948. TB-26B Unarmed variant converted from B-26B for training purposes. VB-26B Unarmed variant converted from B-26B for administrative purposes. A-26C Attack bomber. Production totals: 1,091 A-26Cs were built and delivered, five at Long Beach, California (A-26C-1-DL and A-26C-2-DL) plus 1,086 at Tulsa, Oklahoma (A-26C-16-DT to A-26B-55-DT). About 53 more airframes were built at Tulsa but not delivered to USAAF, some of those later sold to other civil and military customers. A-26C was redesignated B-26C with USAF in 1948. RB-26C Unarmed photo reconnaissance variant converted from B-26C; it carried cameras and flash flares for night photography. Designated FA-26C prior to 1962. TB-26C Unarmed variant converted from B-26C for training purposes. XA-26D Serial no. 44-34776 prototype for the proposed A-26D attack bomber with uprated Chevrolet manufactured R-2800-83 engines, and late model A-26B armament of eight 0.50 in (12.7 mm) machine guns in solid nose and six 0.50 in (12.7 mm) guns in the wing; series of 750 A-26Ds was cancelled after V-J Day. XA-26E Serial no. 44-25563 prototype for the A-26E attack bomber. As with the XA-26D, but with an A-26C-type glass nose; a contract for 2,150 A-26E-DTs was cancelled following V-J Day. XA-26F Prototype 44-34586 was designed for a high-speed A-26F, equipped with two R-2800-83 engines that generated 2,100 hp (1,600 kW). The four-bladed propellers were powered by a General Electric J31 turbojet with a thrust of 1,600 lbf (7.1 kN), which was installed in the rear fuselage. The prototype managed to reach a top speed of 435 mph (700 km/h). However, the series was cancelled due to insufficient performance gains. A-26Z There was a proposed postwar production version of the A-26, unofficially called the A-26Z. This version would have had a more powerful Pratt & Whitney R-2800 radial engine and would feature a raised pilot’s cockpit canopy, an improved cockpit arrangement, and wingtip drop tanks.
If produced, it would have been designated as either A-26G (unglazed nose) or A-26H (glazed nose). However, the USAAF decided in October 1945 that there were enough A-26 aircraft available to meet postwar needs, and therefore, the A-26Z version was not produced. JD-1 U.S. Navy version with one A-26B (AAF Ser. No. 44-34217) and one A-26C (AAF Ser. No. 44-35467) redesignated during World War II, postwar, 150 surplus A-26s for use by land-based Navy utility squadrons (VU) as target tugs and later, drone directors (designated JD-1D) and general utility aircraft. In 1962, the JD-1 and JD-1D were redesignated UB-26J and DB-26J respectively. YB-26K On Mark Engineering prototype for refurbished attack bomber; modifications included rebuilt, strengthened wings, enlarged tail assembly, new R-2800-103W engines with reversible propellers/propeller spinners, dual controls, wingtip tanks, newer avionics, and increased hardpoint/armament enhancements. B-26K Mark Engineering converted 40 B-26Bs or TB-26Bs by replacing two B-26Cs and one JB-26C. The alterations included installing R-2800-52W engines with a power of 2,500 hp (1,900 kW), removing the six wing guns, and eliminating the propeller spinners. The planes were designated as A-26A during their operations in Vietnam in May 1966. However, the A-26As were retired in 1969 after they had exceeded the allotted flying time limit and were no longer considered safe to fly.
RB-26L Two RB-26Cs (44-34718 and 44-35782) were modified for night photography missions. B-26N During the Algerian conflict, the French Air Force (Armée de l’air) utilized modified B-26C planes as night fighters, dubbed unofficially as such.
These planes were equipped with AI Mk X radar previously used on outdated Meteor NF 11 night fighters, along with two underwing gun packs featuring M2 Browning machine guns and SNEB rocket pods. WB-26 The weather reconnaissance version was first produced and used in the Korean War, 2 used by NOAA from 1960 to 1975. Specifications Crew 3 Length 50 ft (15 m) Wingspan 70 ft (21 m) Height 18 ft 6 in (5.64 m) Wing area 540 sq ft (50 m2) Airfoil NACA 65-215 Empty weight 22,370 lb (10,147 kg) Gross weight 27,600 lb (12,519 kg) Max take-off weight 35,000 lb (15,876 kg) Fuel capacity 925 US gal (770 imp gal; 3,500 L) normal + optional 675 US gal (562 imp gal; 2,560 L) ferry tank in the bomb bay. Oil capacity 60 US gal (50 imp gal; 230 L) in two nacelle tanks Powerplant 2 × Pratt & Whitney R-2800-71 Double Wasp or -27s, or -79s 18-cylinder air-cooled two-row radial piston engines, 2,000 hp (1,500 kW) each for take-off Propellers 3-bladed Hamilton Standard Hydromatic, 12 ft 7 in (3.84 m) diameter constant-speed fully-feathering propellers Performance Maximum speed 359 mph (578 km/h, 312 kn) at 16,700 ft (5,100 m) (normal rated power) Cruise speed 266 mph (428 km/h, 231 kn) at 5,000 ft (1,500 m) (62.5% rated power) Range 1,600 mi (2,600 km, 1,400 nmi) without ferry tank at 5,000 ft (1,500 m) at 206 mph (179 kn; 332 km/h) Combat range 700 mi (1,100 km, 610 nmi) Ferry range 3,000 mi (4,800 km, 2,600 nmi) with ferry tank at 5,000 ft (1,500 m) at 210 mph (180 kn; 340 km/h) Service ceiling 28,500 ft (8,700 m) ; 14,400 ft (4,400 m) on one engine Time to altitude 10,000 ft (3,000 m) in 8 minutes 6 seconds Wing loading 51.1 lb/sq ft (249 kg/m2) Power/mass 0.145 hp/lb (0.238 kW/kg) Armament Guns 6 or 8 0.50 in (12.7 mm) M2 Browning machine guns in solid, “all-purpose” nose:
2 0.50 in (12.7 mm) M2 machine guns in glass “bombardier” nose Up to 8 0.50 in (12.7 mm) M2 machine guns paired in four optional underwing pods:
3 0.50 in (12.7 mm) M2 machine guns in each outer wing panel. 2 0.50 in (12.7 mm) M2 machine guns in remote-controlled dorsal turret 2 0.50 in (12.7 mm) M2 machine guns in the remote-controlled ventral turret Rockets Up to 10 5-inch (12.7 cm) HVAR rockets on “zero-length” launch pylons, five under each outer wing panel Bombs Up to 6,000 lb (2,700 kg) capacity:
4,000 lb (1,800 kg) in the bomb bay
2,000 lb (910 kg) carried externally on underwing hardpoints.
Sources Crowood Aviation Series – Douglas A-26 and B-26 Invader-Scott Thompson. Douglas A-26 Warbird Tech 022 – Frederick A Johnsen. A-26 Invader-Squadron Signal “In Action” 37. A-26 Invader-Squadron Signal “In Action” 134. McDonnell Douglas aircraft since 1920: Volume I-René J Francillon. San Diego Air and Space Museum Archive. The National Museum of the U.S. Air Force.