Douglas A/B-26 Invader

Prototypes - Military














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Military Variants - Technical Data, main page

 
 
...To start at the begining
 
The A-26 Invader originally began as a private venture on the part of the Douglas plant at El Segundo, California. The Douglas XA-26 was designed as an improved and updated successor to the Douglas A-20 Havoc.
The aircraft was based on the common light attack/medium bomber configuration: twin-engine, shoulder-mounted wings and tricycle landing gear.
It was one of very few aircraft to be entirely conceived, designed, developed, produced in quantity and used in large numbers, all during World War II. The whole programme was terminated after VJ-Day and anyone might have judged the aircraft finished. With new jets under development, Douglas made no effort to retain any design team on Invader development, neither did the Army Air Force show any interest. Yet this aircraft proved to be of vital importance in the Korean War and again in Vietnam and, by 1963, was urgently being remanufactured for arduous front-line service. Many remain in combat units 30 years after they were first delivered, a record no other kind of aircraft can equal.
The design was prepared by Ed Heinemann at El Segundo as a natural successor to the DB-7 family, using the powerful new R-2800 engine. The Army Air Corps ordered three prototypes in May 1941, one with 75 mm gun, one with four 20 mm forward-firing cannon and four 0.5 in guns in an upper turret, with radar nose, and the third as an attack bomber with optical sighting station in the nose and two defensive turrets. In the event it was the bomber that was bought first, designated A-26B. Much faster than other tactical bombers with the exception of the Mosquito, it was 700 lb lighter than estimate, and capable of carrying twice the specified bomb load. It was the first bomber to use a NACA laminar-flow airfoil, double-slotted flaps and remote-control turrets.

The A-26 was an unusual design for an attack bomber of the early 1940s period, as it was designed as a single-pilot aircraft (sharing this characteristic with the RAF's de Havilland Mosquito, among others). The aircraft was designed by Edward Heinemann, Robert Donovan and Ted R. Smith.

 

 

Three prototypes were built. The XA-26 (serial number 41-19504) was first to be completed, and resembled the A-26C, with a Plexiglas bombardier's nose. It was armed with the remote control upper and lower turrets and was used for most of the early flight tests of the Invader.

The second prototype, the XA-26A (serial number 41-19505) was for the night-fighter version of the Invader. Douglas line drawing show it with a four gun mid-upper turret, but it was built with four 20mm cannons carried in a ventral tray below the bomb bay, a longer radar carrying nose, two crewmen and no turrets. The XA-26A was abandoned when tests showed that it was no better than the Northrop XP-61 Black Widow, which had been undergoing flight tests for two months by the time the XA-26 made its maiden flight.

The third prototype, the XA-26B (serial number 41-19588) was added to the program just after the first two, carried a crew of three and was armed with a solid nose that could carry a wide number of different guns, from .50in machine guns up to a massive 75mm cannon. The XA-26B was the only aircraft to carry the 75mm gun, on the right side of the nose and protected by a retractable cover. The same 75mm gun was installed on the B-25 Mitchell, and proved to be disappointing in service, partly because of its slow rate of fire and partly because suitable targets were often rare.

The Douglas XA-26 prototype (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 there were problems with engine cooling which led to cowling changes and omission of the propeller spinners on production aircraft, plus modification of the nose landing gear after repeated collapses during testing.

The A-26 was originally built in two different configurations. The A-26B had a "solid" nose, which normally housed six (or later eight) .50 caliber machine guns, officially termed the "all-purpose nose", later commonly known as the "six-gun nose" or "eight-gun nose". The A-26C's "glass" nose, officially termed the "Bombardier nose", contained a Norden bombsight for medium altitude precision bombing. The A-26C nose section included two fixed M-2 guns, later replaced by underwing gun packs or internal guns in the wings.

After about 1,570 production aircraft, three guns were installed in each wing, coinciding with the introduction of the "eight-gun nose" for A-26Bs, giving some configurations as many as 14 .50 in (12.7 mm) machine guns in a fixed forward mount. An A-26C nose section could be exchanged for an A-26B nose section, or vice versa, in a few man-hours, thus physically (and officially) changing the designation and operational role. The "flat-topped" canopy was changed in late 1944 after about 820 production aircraft, to a clamshell style with greatly improved visibility.

Alongside the pilot in an A-26B, a crew member typically served as navigator and gun loader for the pilot-operated nose guns. In an A-26C, that crew member served as navigator and bombardier, and relocated to the nose section for the bombing phase of an operation. A small number of A-26Cs were fitted with dual flight controls, some parts of which could be disabled in flight to allow limited access to the nose section. A tractor-style "jump seat" was located behind the "navigator's seat." In most missions, a third crew member in the rear gunner's compartment operated the remotely-controlled dorsal and ventral gun turrets, with access to and from the cockpit only possible via the bomb bay when that was empty.

 

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Above, In the late 1930s, the Special Committee on Future Research Facilities proposed the construction at Langley of a wind tunnel with a 16-foot diameter test section that could evaluate the cowling and cooling of full-sized aircraft engines and propellers. Approval for construction was granted in 1939, and the new 16-Foot High Speed Tunnel (HST) became operational on December 5, 1941, just two days before the Japanese attack on Pearl Harbor. Later in the war, in addition to engine cooling work, testing focused on wing/aileron/elevator flutter problems and bomb/bomb fuse aerodynamics (possibly including the first atomic bombs according to several sources).

While the 16-Foot HST was never Langley's largest or fastest wind tunnel, it did play an important role in the postwar evolution of tunnel design. In the late 1940s, Langley physicist Ray H. Wright observed that the interference caused by wind tunnel walls could be minimized by placing slots in the test section throat, a concept that came to be known as "slotted throat" or "slotted wall tunnel" design. Testing this new design in the 16-Foot HST, Langley engineers found that it allowed for transonic speeds (up to and beyond the speed of sound, Mach 1, approximately 761 mph at sea level). Retrofitted with a new slotted test section throat and re-powered to 60,000 hp, the facility was re-designated the 16-Foot Transonic Tunnel (TT) in December 1950. Work on the slotted test section in the 16-Foot HST was instrumental in Langley winning the Collier Trophy in 1951.

In late 1941, the first test in the 16-Foot High Speed Tunnel was initiated on the Douglas XA-26 Invader configuration, as shown in the photo above.

 
DOUGLAS XA-26 - First Prototype

 
XA-26
Prototype twin engined attack bomber, glass nose.
Produced 1942
Douglas El Segundo, California (DE)
 
The Douglas XA-26 was designed as an improved and updated successor to the Douglas A-20 Havoc. The aircraft was based on the common light attack/medium bomber configuration: twin-engine, shoulder-mounted wings and tricycle landing gear. Douglas engineers began work on the preliminary design study in late 1940. The mockup was completed in the spring of 1941 and the initial Air Corps prototype construction contracts were signed in June 1941. The Army wanted two prototypes built: a light bomber/attack version designated XA-26, and a night fighter/attack version designated XA-26A.

The aircraft was built in about one year at Douglas' El Segundo, Calif., plant under contract number AC-17946. It made its first flight on July 10, 1942. The XA-26 was primarily intended to be a pre-production light bomber prototype and featured a clear nose similar to the A-20J and A-20K. The XA-26 could carry a maximum bomb load of 5,000 pounds (3,000 pounds internal and 2,000 pounds external) and carried a bombardier as part of its three man crew. The defensive armament of the XA-26 was relatively light -- only two forward-firing .50-cal. machine guns and two aft barbettes (dorsal and ventral) fired by the gunner using remote control and periscope sighting. The propellers had large spinners installed designed to improve streamlining; however, the engines suffered from overheating because the spinners restricted the cooling airflow to the engine.

The XA-26 test program was successful but proceeded slowly. The problem was compounded by a lack of production capability at Douglas plants. The Air Corps, although anxious to get the production A-26, was unwilling to disrupt current production of other Douglas aircraft; notably the A-20 and C-47. As a result, the first combat operations using A-26s were delayed until mid-1944. There was no production variant designated A-26, but the A-26C closely resembled the XA-26.


Type

No. Built / Conv'd

     Remarks

XA-26

1

    Twin-eng light attack

    bomber



TECHNICAL NOTES:
Armament: Designed for two forward-firing .50-cal. machine guns in the right forward fuselage, two .50-cal. machine guns in a dorsal turret and two .50-cal. machine guns in a ventral turret, plus provisions for 5,000 lbs. of bombs (3,000 lbs. carried internally in two bomb bays and 2,000 lbs. carried externally on wing racks)
Engines: Two Pratt & Whitney R-2800-27 radials of 2,000 hp each
Maximum speed: 370 mph
Cruising speed: 212 mph

Range:
2,500 miles maximum ferry range
Service ceiling: 31,300 ft.
Span: 70 ft. 0 in.
Length: 51 ft. 2 in.
Height: 18 ft. 6 in.
Weight: Approx. 31,000 lbs. gross takeoff weight
Crew: Three (pilot, navigator/bombardier, gunner)
Serial number: 41-19504 
 

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Douglas engineers began work on the preliminary design study in late 1940. The mockup was completed in the spring of 1941 and the initial Air Corps prototype construction contracts were signed in June 1941. The Army wanted two prototypes built: a light bomber/attack version designated XA-26, and a night fighter/attack version designated XA-26A.
 
The aircraft was built in about one year and made its first flight on July 10, 1942. The XA-26 was primarily intended to be a pre-production light bomber prototype and featured a clear nose similar to the A-20J and A-20K. The XA-26 could carry a maximum bomb load of 5,000 pounds (3,000 pounds internal and 2,000 pounds external) and carried a bombardier as part of its three man crew. The defensive armament of the XA-26 was relatively light -- only two forward-firing .50-cal. machine guns and two aft barbettes (dorsal and ventral) fired by the gunner using remote control and periscope sighting. The propellers had large spinners installed designed to improve streamlining; however, the engines suffered from overheating because the spinners restricted the cooling airflow to the engine.

The XA-26 test program was successful but proceeded slowly. The problem was compounded by a lack of production capability at Douglas plants. The Air Corps, although anxious to get the production A-26, was unwilling to disrupt current production of other Douglas aircraft; notably the A-20 and
C-47. As a result, the first combat operations using A-26s were delayed until mid-1944. There was no production variant designated A-26, but the A-26C closely resembled the XA-26.


Type

No. Built / Conv'd

    Remarks

XA-26

1

    Twin-eng light attack

    bomber



Notes:
Prototype serial number: 41-19504
Built at Douglas' El Segundo, Calif., plant under contract number AC-17946
Accepted by the Army Air Force on Feb. 21, 1944 (Source: Individual Aircraft Record Card XA-26 S/N 41-19504)

SPECIFICATIONS:
Span:
70 ft. 0 in.
Length: 51 ft. 2 in.
Height: 18 ft. 6 in.
Weight: Approx. 31,000 lbs. gross take-off weight
Armament: Designed for two forward-firing .50-cal. machine guns in the right forward fuselage, two .50-cal. machine guns in a dorsal turret and two .50-cal. machine guns in a ventral turret plus provisions for 5,000 lbs. of bombs (3,000 lbs. carried internally in two bomb bays and 2,000 lbs. carried externally on wing racks)
Engines: Two
Pratt & Whitney R-2800-27 radials of 2,000 hp each
Crew: Three (pilot, navigator/bombardier, gunner)

PERFORMANCE:
Maximum speed: 370 mph
Cruising speed: 212 mph
Range: 2500 miles maximum ferry range
Service ceiling: 31,300 ft.

DOUGLAS XA-26A
Second Prototype with two pilot and radar-operator/gunner

 
 
 
j

invaderxa-26a.jpg

The above shot was very kindly sent in by Scott Lindley, thanks Scott

aec01749.jpg

The Douglas XA-26A was a prototype night fighter/attack aircraft ordered at the same time as the XA-26 light attack bomber. The XA-26A was similar to the XA-26 but was designed specifically for the night attack mission. The aircraft had a solid nose designed to carry AI radar used for search, intercept and attack. Since the nose was filled with electronics, there was no room for attack weaponry. Douglas engineers solved the problem by designing a ventral "tub" housing four 20mm cannons. The cannon machinery and ammunition boxes took up a relatively large amount of space in what was the forward bomb bay of the XA-26. Only the aft bomb bay was retained and gave the XA-26A a maximum internal bomb load of just 2,000 pounds. Defensive armament consisted of a remote controlled dorsal barbette with four .50-cal. machine guns.

Testing of the XA-26A was successful; however, its performance was about the same as the
Northrop P-61 "Black Widow" night fighter. The P-61 was already in production and Douglas was short of production capacity for new aircraft so the XA-26A program was canceled after only a single prototype was built.

There was a Douglas A-26A, but this was a re-designation of the Vietnam-era
B-26K. The B-26K was a rebuilt and updated B-26B (the A-26B was re-designated B-26B in 1948 when the A designation was dropped).


Type

No. Built / Conv'd

     Remarks

XA-26A

1

     Night attack prototype



Notes:
Prototype serial number: 41-19505
Built at Douglas' El Segundo, Calif., plant under contract number AC-17946
Accepted by the Army Air Force on Sept. 27, 1943

SPECIFICATIONS:
Span: 70 ft. 0 in.
Length: 52 ft. 5 in.
Height: 18 ft. 6 in.
Weight: Approx. 28,900 lbs. gross take off weight
Armament: Designed for four 20mm cannons in a ventral tub aft of the nose landing gear and four .50-cal. machine guns in a remote-controlled dorsal barbette plus provisions for 2,000 lbs. of bombs.
Engines: Two
Pratt & Whitney R-2800-27 radials of 2,000 hp each
Crew: Two (pilot, radar operator/navigator/gunner)

PERFORMANCE:
Maximum speed: 365 mph
Cruising speed: 264 mph
Range: 2500 miles maximum ferry range
Service ceiling: 25,900 ft.

DOUGLAS XA-26B
Three seat ground attack prototype with an unglazed nose housing a 75-mm cannon.

 
 
 
l

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The above four shots were kindly sent in by Cliff Gisinger, thanks Cliff.
 
 

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The Army Air Corps contract (AC-17946) was initially signed in early June 1941 and included provisions for two prototype aircraft. The first, designated XA-26, was for a light attack bomber. The second, designated XA-26A, was for a night attack fighter. In late June 1941, the Air Corps amended the contract to include a third aircraft, designated XA-26B, to be designed as a low altitude attack aircraft. The XA-26B had the same basic design as the XA-26, however, the clear glass bombardier's nose was replaced by a solid nose to house a 75mm cannon.

The testing program for the XA-26B was successful, and the Army ordered the aircraft into production; however, the 75mm cannon had a slow firing rate and was prone to jamming, so various alternate armament configurations were considered. Several combinations of 75mm or 37mm cannons and .50-cal. machine guns were tried. Armament testing continued even after the production of A-26Bs had started. Eventually, the aircraft nose armament was decided upon and early block A-26Bs had six .50-cal. machine guns in the nose while later block -B models had eight .50-cal. machine guns in the nose. The XA-26B had the same large propeller spinners as the XA-26 and XA-26A. It also had the same cooling problems as the other aircraft and the spinners were deleted on production A-26Bs.


Type

No. Built . Conv'd

     Remarks

XA-26B

1

    Attack prototype



Notes:
Prototype serial number: 41-19588
Built at Douglas' El Segundo, Calif., plant under contract number AC-17946
Accepted by the Army Air Force on June 30, 1943 (
Source: Individual Aircraft Record Card XA-26B S/N 41-19588)

SPECIFICATIONS:
Span:
70 ft. 0 in.
Length: 50 ft. 0 in.
Height: 18 ft. 6 in.
Weight: Approx. 35,000 lbs. gross take off weight
Armament: Two .50-cal. machine guns in a dorsal barbette, two .50-cal. machine guns in a ventral barbette and one forward firing 75mm cannon plus provisions for 6,000 lbs. of bombs (4,000 lbs. internal and 2,000 lbs. external on wing racks)
Engines: Two
Pratt & Whitney R-2800-27 radials of 2,000 hp each
Crew: Three (pilot, navigator/cannon loader, gunner)

PERFORMANCE:
Maximum speed:
Approx. 350 mph
Cruising speed: Approx. 280 mph
Range: 3,200 miles maximum ferry range
Service ceiling: 22,000 ft.

XA-26C 
Projected prototype with nose mounted 20mm cannon, cancelled.

DOUGLAS XA-26D 
Prototype contract cancelled after testing

 
The Douglas XA-26D was designed as an improved version of the A-26B. The D model was a solid nose version primarily intended for use in the ground attack role. The aircraft was equipped with 14 forward-firing .50-cal. machine guns -- eight in the nose (two vertical rows of four guns) and six more in the wings. The engines were upgraded to a more powerful version of the Pratt & Whitney R-2800 radial engine also. The top speed of the XA-26D was slightly more than 400 mph.

A contract for 750 production A-26Ds was cancelled at the end of World War II.

At least one A-26B was upgraded to XA-26D design specifications; however, there may have been two (or more) aircraft converted. Most sources list the serial number of the XA-26D as 44-34776; however, the aircraft data card for this aircraft makes no reference to a conversion program. Another B-26B (S/N 44-34100) does have an upgrade history to A-26D standards and the museum has (poor quality) copies of photos with A-26D listed as the aircraft type. It appears that both aircraft were held at the Douglas plant for use in test programs. S/N 44-34100 was accepted on Jan. 31, 1945, but not available until Oct. 31, 1945. The individual aircraft record card has a notation indicating the aircraft was to remain at the contractor's plant for 180 days. The first record entry listing the aircraft as an A-26D was on Nov. 11, 1945. The other aircraft (S/N 44-34776) was available on Aug. 14, 1945, but not acceptable until March 15, 1946. There is no record of the aircraft ever being converted to A-26D specs.


Type

No. Built / Conv'd

     Remarks

XB-26D

1

    Improved B-26B



Prototype serial number: 44-34100 (B-26B-45-DL) or 44-34776 (B-26B-71-DL)

SPECIFICATIONS:
Span:
70 ft.
Length: 50 ft. 9 in.
Height: 18 ft. 6 in.
Weight: 38,000 lbs. loaded
Armament: 18 .50-cal. machine guns (8 nose, 6 wing, 2 each in dorsal and ventral barbettes) plus 4,000 lbs. of bombs (internal)
Engines: Two
Pratt & Whitney R-2800-83
radial engines of 2,100 hp each

PERFORMANCE:
Maximum speed:
403 mph
Cruising speed: 310 mph
Range: 1,500 miles (4,500 miles with bomb bay auxiliary fuel tank)
Service ceiling: 31,000 ft.

DOUGLAS XA-26E 
Prototype contract cancelled after testing

 
The Douglas XA-26E was designed as an improved version of the A-26C in the same way the XA-26D was an improved version of the A-26B. The major improvement to the XA-26E was the installation of more powerful Pratt & Whitney R-2800 radial engines. The top speed of the aircraft rose to slightly more than 400 mph, and the Army Air Force planned for 1,250 aircraft. The end of World War II and the mass cancellation of production contracts ended the A-26E program.

At least one B-26C was returned to the Douglas plant for modification to XA-26E specifications.


Type

No. Built / Conv'd

     Remarks

XA-26E

1

    Improved B-26C



Prototype serial number: 44-35563 (B-26B-40-DT)

SPECIFICATIONS:
Span: 70 ft.
Length: 51 ft. 3 in.
Height: 18 ft. 6 in.
Weight: 35,000 lbs. loaded
Armament: 12 .50-cal. machine guns (2 nose, 6 wing, 2 each in dorsal and ventral barbettes) plus 4,000 lbs. of bombs (internal)
Engines: Two
Pratt & Whitney R-2800-83 radial engines of 2,100 hp each

PERFORMANCE:
Maximum speed: 403 mph
Cruising speed: 310 mph
Range: 1,500 miles (4,500 miles with bomb bay auxiliary fuel tank)
Service ceiling: 31,000 ft.

DOUGLAS XA-26F 
Prototype for a high-speed version of the Invader

 

The newly-emerging jet engine technology was not lost upon Douglas who was busy developing the very advanced XB-42 (piston) and XB-43 (jet) series of bombers. However, they also knew that the A-26 Invader had very high performance and speculated how that performance could be enhanced if jet power was somehow incorporated into the airframe. At the same time, propeller technology was advancing so Douglas approached the USAAF with a proposal for a mixed power Invader and a contract was issued to convert A-26B-61-DL s/n 44-34586 to an experimental mixed-power platform.

Given the designation XA-26F, the modifications were fairly straightforward. The extra powerplant was a General Electric Model 7E-116-4 gas turbine and to install the unit in the rear fuselage, the gunner's sighting station and all related equipment was removed. The upper and lower turrets were also removed along with the Station 0 armor plate. The electrical equipment in the former gunner's compartment was relocated along with the radio compass. The SCR-695 (IFF) radio and radio compass loop antenna were also relocated while the aft portion of the flight control cables had to be rerouted.

A large air scoop for the jet was added atop the fuselage while the tail cone was refashioned into a tail pipe. A long exhaust pipe and shroud assembly ran from the engine to the tail cone. Under where the top turret would have been, a 125-gallon fuel cell was installed to hold the jet's Spec. AN-F-32 Grade K JP-1 (kerosene) fuel along with an eight-quart tank for the AAF Spec. 3580D medium grade oil. The fuel system was controlled by the operation of a master switch and the throttle. Fuel pressure ranged from 20 psi at engine idling speed to 380 psi maximum engine operating speed. The turbine would act as an assist to improve combat performance and make takeoffs possible from short runways or with extra heavy loads.

All flight controls, their maintenance and operation, remained unchanged except for cable routing in the vicinity of the aft engine installation. The throttle for the aft engine was isodraulically operated. This unit was self-contained and was in no way connected to the airplane hydraulic system.

The XA-26F was not to be a stripped-out test vehicle for it carried an eight-gun nose and a six-gun wing. Also, large four-blade paddle-style propellers had been added along with a set of spinners that had been made for the prototypes and early production aircraft. The engines were P&W R-2800-83s capable of 2100-hp each.

Before serious testing could really get underway, the war was over. However, the Air Force considered the XA-26F an important test vehicle and continued flying the aircraft in different configurations. On June 1946, the XA-26F covered a 621-mile (1000 kilometer) course with a 1000 kilogram load at an average air speed of 413 mph. The aircraft was being flown by Lt. Col. T.P. Gerrity and Capt. W.K. Rickert. With all three engines operating, the XA-26F reached a top speed of 435 mph at 15,000 feet.

With a whole new generation of jet warplanes on the horizon, it was obvious that it would not make practical sense to convert operational Invaders to the A-26F configuration. However, this did not mean the prototype's career was over.

Fitted with standard propellers and minus the spinners, the XA-26F was assigned to the Shell Oil Company in late 1949 for flight test work. Two oil company engineers were positioned in the cockpit while another two were crammed into the rear fuselage along with the jet. Under the direction of D.N. Harris, Shell's Project Engineer of Flight Research, the XA-26F was operated on numerous flights between Los Angeles and Oakland, California, to obtain experimental data on aviation fuels.

As one flight test engineer stated in a period publication, when both P&Ws were running at full power and the jet cut in it was like, "a kick in the butt."

When this valuable research was concluded in the 1950s, the XA-26F was stored for a period and then transferred to a technical school in Florida where it survived until the early 1970s when it was scrapped.

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On June 1946, the XA-26F covered a 621-mile (1000 kilometer) course with a 1000 kilogram load at an average air speed of 413 mph. The aircraft was being flown by Lt. Col. T.P. Gerrity and Capt. W.K. Rickert (Pictured above) With all three engines operating, the XA-26F reached a top speed of 435 mph at 15,000 feet."

Records set by the XA-26F
 
Speed over 1000 km with 1000 kg payload : 660.53 km/h

Date of flight: 20/06/1946
Pilot: T. P. GERRITY (USA)
Crew: W.K. Rickert
Course/place: Dayton, OH (USA)

Aircraft:
Douglas XA-26F (Wright R-2800-83 and GE-1-16, 2000 hp/1600 lbs)

 

 

Sub-class : C (Aviation with engine)
Without refuelling in flight
Speed over 1000 km with 1000 kg payload : 660.53 km/h

Date of flight: 20/06/1946
Pilot: T. P. GERRITY (USA)
Crew: W.K. Rickert
Course/place: Dayton, OH (USA)

Aircraft:
Douglas XA-26F (Wright R-2800-83 and GE-1-16, 2000 hp/1600 lbs
)

 

Serial #: 44-34586
Construction #: 27865
Civil Registration:
  N66368
Model(s):
  A-26B
  XB-26F
Name: None
Status: Unknown
Last info: 1972

 

 

History:
Lindsay Hopkins Vocational School, Miami Airport, FL, 1964-1972.
- Registered as N66368

Built as DOUGLAS XA-26F - Prototype for a high-speed version of the Invader
 
Started out as an A-26B but modified in late 1945 as XA-26F with
J31 turbojet aft of bomb bay.  Donated to Lindsay Hopkins Vocational
School in the 1950s, and was on the civil registry at least
1964-1969 as N66368.  USed for ground instruction at Miami
Airport and reportedly scrapped in 1972.


 

Type

No. Built / Conv'd

Remarks

XA-26F

1

Jet augmented XA-26D



Prototype serial number: 44-34586 (B-26B-61-DL)

SPECIFICATIONS:
Span: 70 ft.
Length: 50 ft. 9 in.
Height: 18 ft. 6 in.
Weight: 33,000 lbs. loaded
Armament: 14 .50-cal. machine guns (8 nose and 6 wing)
Engines: Two
Pratt & Whitney R-2800-83 radial engines of 2,100 hp each and one General Electric J31 turbojet with 1,650 lbs. thrust

PERFORMANCE:
Maximum speed: 435 mph (all three engines at military power)
Service ceiling: 33,000 ft.

Note: Could the two photos below, be of the XA-26F prior to her modification.
Any help would be appreciated please. ( Look at the spinners)

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a26w1w1.jpg

A-26D

The Douglas A-26D Invader was an improved version of the solid-nosed A-26B, with more powerful engines. A single prototype was produced, probably by fitting a standard A-26B with two Chevrolet built 2,100hp R-2800-83 engines. This increased the aircraft's top speed by 80mph, and Douglas received an order for 750 A-26Ds, but this was cancelled after the end of the war in the Pacific and before any aircraft had been completed.

A-26E

The Douglas A-26E Invader was to have been a version of the glass nosed A-26C but with the same more powerful 2,100hp Chevrolet-built R-2800-83 engines as the A-26D. As with the A-26D this would have lifted the aircraft's top speed up to 400mph, and as with the A-26D the end of the Second World War meant that no A-26Es were built.

DOUGLAS A-26Z

Prototype cancelled

 

Unofficial designation for a proposed postwar production version of the A-26. It was to have a more powerful version of the Pratt & Whitney R-2800 radial engine and was to be fitted with such features as a raised pilot's cockpit canopy, an improved cockpit arrangement and wingtip drop tanks. If produced, the unglazed nose version would have been designated A-26G and the glazed nose version A-26H. However, in October 1945, the USAAF concluded that there were enough A-26 aircraft to meet postwar needs, consequently, the "A-26Z" version was not produced.

 DOUGLAS A-26G/JD-1
 
Prototype cancelled

 
The Douglas A-26G and A-26H were designations assigned to design studies done for an improved version of the A-26B/C. The -G model was based on the solid nose design of the A-26B (and XA-26D) while the -H model was based on the bombardier (glass) nose A-26C (and XA-26E). At the end of World War II, production plans for the -D and -E model Invaders was canceled. The Douglas proposal for the improved -G and -H model A-26 was submitted to support peace time needs; however, the Army Air Forces had sufficient numbers of A-26Bs and -Cs and did not order the -G and -H models into production. No prototypes were built of either aircraft. Two features of the Douglas design were wing tip fuel tanks and a raised cockpit for increased pilot visibility. These features would be incorporated into the B-26K project more than 15 years after the cancellation of the A-26G/H project.

The B-26J designation was assigned to U.S. Navy JD-1s still in service in 1962 when the tri-service naming scheme went into effect. The Navy obtained 150 surplus A-26Cs from the Army and converted them for use as target towing and utility aircraft. In 1962 all JD-1s still in service were re-designated UB-26J. Some JD-1s were adapted for use as
drone director aircraft and given the designation JD-1D. In 1962 these aircraft were re-designated DB-26J.

Type

No. Built / Conv'd

    Remarks

A-26G

0

    Improved A-26B

A-26H

0

    Improved A-26C

B-26J

-

    Re-design of US Navy JD-1

DOUGLAS YB-26K
Prototype for "Counter Invader"

 
The B-26B was used in Vietnam in the early 1960s in the armed reconnaissance role. The 4400th Combat Crew Training Squadron (CCTS) initial stated purpose was to provide advisors and training in support of counter insurgency operations. The aircraft began flying in 1961 in support of various operations including Ranch Hand and Farm Gate; however, with two losses due to structure failures, the B-26Bs were withdrawn in 1964.

The B-26Bs were suited to the counter insurgency role, so the USAF ordered an improved prototype aircraft built with the designation YB-26K. A B-26C (S/N 44-35684) was sent to On Mark Engineering Co. for conversion. The engines were updated to 250-hp Pratt & Whitney R-2800-103W radial engines, each equipped with a larger propeller. The wing was strengthened, 165-gallon wing tip fuel tanks were added, and four weapons pylons were installed on each wing. The vertical stabilizer and rudder were enlarged. The cockpit was adapted for dual controls and improved, updated avionics were installed. The nose retained the eight .50-cal. machine gun arrangement, and the wings each had three .50-cal. machine guns.

Testing began in January 1963 and showed the aircraft to be well suited for the planned counter insurgency mission over Southeast Asia. Based on the success of the YB-26K, a production contract for conversion of 40 more aircraft was signed later in the year.

Type

No. Built / Conv'd

     Remarks

YB-26K

1

    Counter insurgency mod.



Notes:
Prototype serial number: 44-35634 (B-26C-40-DT)
First flight was Jan. 28, 1963

SPECIFICATIONS:
Span: 71 ft. 6 in.
Length: 51 ft. 7 in.
Height: 19 ft.
Weight: 38,314 lbs. maximum
Armament: Eight .50 cal. nose machine guns, six .50-cal. machine guns in the wings, eight wing pylons capable of carrying 8,000 lbs. of mixed ordnance, and 4,000 lbs. of bombs internally
Engines: Two
Pratt & Whitney R-2800-103W.s of 2,500 hp (maximum with water injection)
Crew: Two
Cost: $577,000

PERFORMANCE:
Max. speed: 323 mph/281 knots
Cruising speed: 310 mph/270 knots
Range: 2,700 statute miles/2,346 nautical miles
Service ceiling: 30,000 ft

 

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yb-26kfirstflight7.jpg

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The above eight photos of the YB-26K Prototype were sent in by Richard E. Fulwiler of Portland, Oregon. 
 
Reference: Richard grew up near the Van Nuys Airport, home of On Mark, and had access to their facility until Marksman C #7 and 8 were started, coinciding with the B26K modifications. He was present on the return of the prototype of the YB26K (#35634) from its first flight when he was 16.
 
Thank you Richard
 
 
 
















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