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	Specifications - Propulsion

	Specifications - Armament

	Associated reading Flying the A-26 Invader Flight characteristics of the Douglas A-26 Invader Stability control tests Performance tables Performance comparisons Ditching the Douglas A-26 Invader

	General information for A/B-26 Invader   Manufacturer: The Douglas Aircraft Co. Inc., Santa Monica, Cal, USA.   Manufacturing Sub divisions: Douglas El Segundo, California (DE) Douglas Long Beach, California (DL) Douglas Tulsa, Oklahoma (DT) Boeing Aircraft Beech Aircraft   Military modifications undertaken by: Aero Trades Inc. Grand Central Aircraft Company On Mark Engineering Intermountain Aviation Hamilton Aircraft   Designed by: E Heinemann, Ted R. Smith and Robert Donovan Sales manager for Douglas Aircraft: Nat Paschall Sales manager for On Mark Engineering: - William Boone Note: On Mark contracted to convert 18 No B-26B and 22 No B-26C Invaders, to On Mark B-26K counter invader status, total cost $16m.  Designations: A-26, B-26, JD First official flight: XA-26 10/07/1942 at Mines Field, El Segundo. Last bona fide Military aircraft retired: 1972 44-34610 - National Guard Bureau Douglas test Pilots: Benny Howard / John F Martin Factory production period: 1942 - 1945 Primary service period: 1944 - 1969 Total number of sorties During the war in Europe: 11,567 Working life: 1944 - 2008 ( Incl. Air tanker ops )  Number built: 2452 Number cancelled: 4,000 ( before the end of WWII ) MMAC (Material Management Aggregation Code) - DK Type/Weight class - L2P/L   Military nickname / Given name: Invader Counter Invader Little hummer / Little racer Blue Goose / The Blivet ( CIA ) Marksman ( CIA )   Unit cost: US$242,595 (basic airframe 1943) On Mark Marksman C - $361,492.00 ( Late 1961 )   Today's cost: US$145,000 ( £75,000.00 Pounds stirling )  market value for an approx. 5000 Hours airframe   N7079G Currently used as executive company transport     Note: It was the first medium bomber to use a NACA laminar-flow airfoil, double-slotted flaps and remote-control turrets. All metal, semi monocoque fuselage. Aluminum alloy monocoque engine mount. Engines were cooled with a new type of high entrance velocity cowling. It was the last twin engine propeller driven bomber to be built for the US Air Force.   Aircraft classification number The aircraft classification number (ACN) is a number expressing the relative effect of an aircraft on the runway pavement for a specified standard subgrade category (ICAO). Subgrade support strength category The ranges of subgrade strength covered by these standard subgrade categories (designated as A, B, C and D) are shown below. Flexible pavements The flexible pavements have four subgrade categories: A. High Strength – CBR 15 (All CBR above 13%). B. Medium Strength – CBR 10 (For CBR between 8% to 13%). C. Low Strength – CBR 6 (For. CBR between 4% to 8%). D. Ultra Low Strength – CBR 3 (For CBR below 4%). Rigid pavements The rigid pavements have four subgrade categories: A. High Strength – Subgrade k = 150 MN/m3 (550 lb/in3) (All k values above 120 MN/m3). B. Medium Strength – k = 80 MN/m3 (300 lb/in3) (For values between 60 to 120 MN/m3). C. Low Strength – k = 40 MN/m3 (150 lb/in3) (For values between 25 to 60 MN/m3). D. Ultra Low Strength – k = 20 MN/m3 (75 lb/in3) (All k values below 25 MN/m3). Aircraft Classification Numbers (ACNs)                                         Flex pav'nt CBR%      Rigid pav'nt k (MPa/m3)             Max Wt kN    Tire Pr MPa    High  Med  L  V L        High  Med  L  ultra L A-26               120                 .40                  7        8    10   11             8        8      9       9 B-26               156                 .48                  9       11   13   14            10      11     11     12

	Standard A/B-26 Invader specifications General Specifications     Length: 51' 3" (15.24 m) Height: 18' 6" (5.64 m) Wingspan: 70' (21.34 m) Wing Area: 540 Sq. Feet (50.17 m²) Empty weight: 22,850 lb (10,365 kg) Loaded weight: 27,600 lb (12,519 kg) Max takeoff weight: 35,000 lb (15,900 kg) Take off dist. required at gross max weight: 4000ft Fuel capacity, Int: 1,332.1 Imp gal Fuel capacity, Ext: 383 Imp gal in two drop tanks Propulsion Number of Engines: 2 Powerplant: Pratt & Whitney R-2800-27 "Double Wasp" 18-cylinder radial engines; Horsepower: 2000 HP each (1,500 kW) Weight 2,350lbs Propellers: Hamilton Standard 33D50 Wake category: Medium   Performance Normal Range: 1400 miles (1,200 nm, 2,300 km) Maximum (ferry) range: 3200 miles Cruise Speed: 284 mph Max Speed: 355 mph (308 knots, 570 km/h) at 15,000 feet Ceiling: 22,100 feet (6,700 m) Initial rate of climb: 10,000 ft in 8 min 6 sec Rate of climb: 1,250 ft/min (6.4 m/s) Wing loading: 51 lb/ft² (250 kg/m²) Power/mass: 0.145 hp/lb (108 W/kg) Combat radius (Nm): B-26B-839, B-26C-775, B-26K-606 Combat target altitude: Sea level     Airfoils Wing Root Airfoil: NACA 65-215 Wing Tip Airfoil: NACA 65-215 Note: The rudder on the B-26K, was enlarged to improve single-engine handling. Diving Speeds: 26,000 lbs gross  -  425 IAS 32,000 lbs gross  -  400 IAS 35,500 lbs gross  -  360 IAS Fuel capacity Internal: 6.056 l Plus provision for 1.173 l if the ventral barbette was omitted (mostly the Pacific theatre) Fuel capacity external: 1.741 l in two drop tanks. Main Tanks: 300 gals each Aux Tanks: 100 gallons each Bomb Bay Tank: 125 gallons Total Normal: - 925 gallons Ferry Tank: 675 gallons Total Ferry: - 1600 gallons     Note: The ventral barbette was dropped for an additional fuel tank with 258.1 Imp gal (310 US gal/1.173 l) in some cases for Pacific operations. Option of 460 US gal fuel in two wing mounted drop tanks, 1 hard point each. Normal fuel consumption at cruise approx 150 gph Also a standard self sealing 675 gal ferry fuel tank could be installed in the bomb bay by using standard bomb shackles. Guns - Typical, late model A-26B 8× 0.50 in (12.7 mm) M2 Browning machine guns in the nose 6-8 × 0.50 in M2 machine guns in/under the wings (internally mount or gun pods) 2× 0.50 in M2 machine guns in remote-controlled dorsal turret 2× 0.50 in M2 machine guns in remote-controlled ventral turret (or fuel cell) Bombs: 6,000 lb (2,700 kg)-4,000 lb in the bomb bay and 2,000 lb external on the wings (post A-26C-45-DT block introduction).   Note: The C-Model, was typically was built with 2 forward firing .50's, plus 2-twin barbettes and additional guns were added to the wings once delivered for operations in the field. C-models performed as pathfinders and observation aircraft often, and were fewer in production numbers. Original A-26B from Original Pilot’s Training Manual was listed as having 6 configurations for the "All Purpose Nose" (The B model) – not counting the original two "4-pack" gun pods option that could be mounted under the wings (before the 6 internal .50's - 3 per wing - were done with/after 45-block). 6 -.50s (later upped to 8) – most commonly ordered configuration 1 - 37mm and 4 - .50's 1 - 37mm and 2 - .50's 2 - 37mm’s (gah!) 1 - 75mm and 1 - 37 mm (Racks held 20 rounds for manually loaded 75mm) 1 - 75mm and 2 -.50's (30 actually ordered and deployed)   Ordnance Up to 6,000 lb, consisting of 2 × 2,000 lb max in 2 internal bays, plus 4 underwing hardpoints rated at 500 lb each. Total of 20 hard points, but maximum of 16 could be used at any one time points. Loadout was generally: 4 × 1,000 lb, or 8 × 500 lb, or 8 × 250 lb, or 12 × 100 lb internal 4 × 500 lb or 4 × 250 lb under the wings additional typical, 4 X 100 lbs possible Torpedoes/rockets: 14 × 5 inch rockets under the wings instead of bombs.   Note: 5" HVAR “Holy Moses” Length: 72 inches Weight: 140 lbs Maximum Velocity: 1,375 fps relative to aircraft launch velocity. It used a 5" diameter rocket motor with 24 lbs of propellant. First combat use July 1944; but supplies were not adequate until the Spring of 1945.   Original Training Guide also lists 2 torpedoes carried internally (doors open), but I don't think it was ever used this way in WWII, since by that time, Axis fleets were mostly done, and an A-26 low and slow for torps is not a good use of that plane.) Ammunition for B-model: 500 rpg for each twin .50 barbette 400 rpg for 6 wing-mounted .50 cal MG options for nose 6 - nose mounted .50's w 400 rpg 8 - nose mounted .50's w 400 rpg 1 - 75mm cannon w 20 rds, 3-5 second load time (manual) plus 2 x .50's with 400 rpg (no 37mm options ever ordered from factory I am aware of, and may have been intended for Lend-Lease....so I left them out). Ammunition for C-model: 500 rpg for each twin-.50 barbette 400 rpg for 2 forward nose .50's and 6 wing-mounted .50's Interior colours   The shop primer coating should be darkened with primer yellow zinc chromate (AN-TT-P-656) and with a specified amount of black enamel added-used on all parts needing a primer coating. Interior Surfaces and exceptions. (1) Unless otherwise specified in the following paragraphs, no finish in addition to the shop coating should be applied to the interior aluminum and alum· inum alloy pans and surfaces of the airplane. (a) Small extrusions such as bulb angles should be shop coated in random lengths. No finish is re· quired after cutting length. Large extrusions such as cap strips should be shop coated after all machining is complete. (b) There should be no touch-up of scratches, rivet heads or points, except the screw heads on the instrument panel. (c) A double spray coat of flat black lacquer which conforms to the requirements or Army-Navy Specification AN-TI-L-51 should be applied to exposed interior surfaces of the following: 1. INSTRUMENT PANEL 2. PILOTS COCKPIT COWL. 3. PILOTS NOSE ENCLOSURE. (d) Emergency units or areas thereof which require prominent markings should have a red back- ground for the stenciling. (e) No finish should be applied to interior stainless steel except where insulation of dissimilar metals is necessary. (f) No finish should be applied to interior metal parts and surfaces in the engine section forward of the firewall-Exceptions are motor mounts, dissimilar metals and magnesium alloys which are finished as specified in paragrapb 3. h. (3), this section. (2) Propellers should receive one coat of black camouflage enamel. The tips should be coated with yellow camouflage enamel for a distance of four inches back from the tips. Touching-up propellers is not necessary. Miscellaneous treatment. (I) Additional protection (other than shop coatings. cadmium plating, etc.) must be applied to combinations of dissimilar metal assemblies. The additional coating may be given to either of the contacting surfaces. Forward of the firewall, the only protection necessary is between stainless steel and aluminum alloys. A coat of darkened primer, AN-TT-P-656, should be applied. Exterior colours The only common addition the exterior surfaces was the application of a Matt black or Olive green colouring to both the inner nacelles and the section forward of the cockpit windshield to alleviate sun glare.

	Clarification Note: I had a mail recently from a C. O. Smith who worked with the A-26 during the Korean war. He wrote, "In your description of the armament on the B-26 you indicated that the bomb load was 4000 Ib's."  He continues, During the Korean war, when  we carried only 500 Ib bombs, the load was 10 -500 Ib's, six in the bomb bay  plus  two 500 Ib bombs under each wing.  In addition we often carred two flares - one on each wing. When we carred 260 Ib frags, we double and tripple hung them in the bomb bay (three double hung on one side and three tripple hung on the other side) so that we carred 15- 260 frags plus the four  500 # wing bombs. for a total load of 5900 Ib's. We flew them off the runway at a max gross of 40K Ib's.

	A-26D Engines: Two Chevrolet built 2,100hp R-2800-83 engines  Maximum speed: 453 mph Cruising speed: 364 mph   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 Engines: Two Chevrolet built 2,100hp R-2800-83 engines Maximum speed: 453 mph Cruising speed: 364 mph 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.

	FA-26C   Engines: Two Pratt & Whitney R-2800s of 2,000 hp each  Maximum speed (A-26C): 373 mph Cruising speed (A-26C): 284 mph Range (A-26C): 1,400 miles Service ceiling (A-26C): 28,000 ft. Span: 70 ft. Length: 51 ft. 3 in. Height: 18 ft. 3 in. Weight: Approx. 35,000 lbs. loaded

	RB-26C    Engines: Two Pratt & Whitney R-2800s of 2,000 hp each Maximum speed (A-26C): 373 mph Cruising speed (A-26C): 284 mph Range (A-26C): 1,400 miles Service ceiling (A-26C): 28,000 ft. Span: 70 ft. Length: 51 ft. 3 in. Height: 18 ft. 3 in. Weight: Approx. 35,000 lbs. loaded

	RB-26L   Engines: Two Pratt & Whitney R-2800-27 (or -71 or -79) radials of 2,000 hp. each Maximum speed: 322 mph Cruising speed: 278 mph Range: 2,900 miles maximum ferry range Service ceiling: 24,500 ft. Span: 70 ft. 0 in. Length: 50 ft. 8 in. Height: 18 ft. 6 in. Weight: Approx. 41,800 lbs. gross takeoff weight Crew: Three (pilot, navigator, gunner)

	DB-26B   Engines: Two Pratt & Whitney R-2800-27 (or -71 or -79) radials of 2,000 hp each Maximum speed: 322 mph Cruising speed: 278 mph Range: 2,900 miles maximum ferry range Service ceiling: 24,500 ft. Span: 70 ft. 0 in. Length: 50 ft. 8 in. Height: 18 ft. 6 in. Weight: Approx. 41,800 lbs. gross takeoff weight

	EB-26B   Engines: Two Pratt & Whitney R-2800-27 radials of 2,000 hp each Maximum speed: Approx. 150 mph ground run (aircraft could not fly) Span: N/A (outer wings were removed) Length: 50 ft. 8 in. Height: 18 ft. 6 in.

	FA-26C-26C ( 1945, night recon aircraft with cameras and radar )   Engines: Two Pratt & Whitney R-2800s of 2,000 hp each  Maximum speed (A-26C): 373 mph Cruising speed (A-26C): 284 mph Range (A-26C): 1,400 miles Service ceiling (A-26C): 28,000 ft. Span: 70 ft. Length: 51 ft. 3 in. Height: 18 ft. 3 in. Weight: Approx. 35,000 lbs. loaded

	RB-26C   Engines: Two Pratt & Whitney R-2800s of 2,000 hp each Maximum speed (A-26C): 373 mph Cruising speed (A-26C): 284 mph Range (A-26C): 1,400 miles Service ceiling (A-26C): 28,000 ft. Span: 70 ft. Length: 51 ft. 3 in. Height: 18 ft. 3 in. Weight: Approx. 35,000 lbs. loaded

	EB-26B/C ( Aircraft used for missile guidance research )   Armament: None Engines: Two Pratt & Whitney R-2800-27 radials of 2,000 hp each Maximum speed: Approx. 150 mph (aircraft could not fly) Span: N/A (outer wings were removed) Length: 50 ft. 8 in. Height: 18 ft. 6 in. Serial number: 44-34137 (originally A-26B-45-DL)

	On Mark B-26K ( A-26A ) Counter Invader   Crew: 2 Length: 51 feet 7 3/16 inches Wingspan: 71 feet 6 inches (over wingtip tanks) Height: 19 feet 0 inches Wing area: 540 square feet. Empty Weight: 25,130 pounds empty Loaded Wieght: 37,000 pounds loaded Max takeoff weight: 39,250 pounds maximum. Powerplant: Two Pratt & Whitney R-2800-52W air-cooled radials, each rated at 2500 hp for takeoff and 1750 hp at 15,000 feet. Performance: Maximum speed: 323 mph at 15,000 feet, 291 mph at sea level. Cruising speed: 169 mph. Stalling speed: 114 mph. Airfoils Wing Root Airfoil: NACA 65-215 Wing Tip Airfoil: NACA 65-215   The following items were some of the more significant and visible mods included in upgrading to the On Mark B-26K. Higher powered R-2800 Engines. New props. With reversing capability Wing tip fuel tanks Improved and strengthened wings with more pylonsRemanufactured fuselagesUpdated avionics. Landing Gear strengthened and KC-135 wheels and brakes used. Larger rudder installed Dual controls and a standardized cockpit Provisions for JATO use Gun armament was standardized with an eight gun nose. Turrets were deleted. Larger rudder installed, the actual difference is in the chord of the rudder - it was widened 12 inches, in an attempt to lower the VMC (minimum single engine control speed with one engine operating at take-off power and the second engine is windmilling - rather critical on any twin engine aircraft on take off - on the early model A/B 26s it was 140 kts) as a single pilot facility. Note: An air tanker company that operated 9 A-26 Bs and Cs for air tanker ops, looked into the possibility of swapping the K model rudder to their aircraft for single pilot operation. For the most part, it was a straight forward swap. Simply remove the original B/C rudder, swap positions on the rudder attach brackets (Top bracket moved to the lower position and bottom moved to the top position) and bolt on the K rudder. However, the FAA insisted that we also had to install the two rows of vortex generators that had been installed vertically on the right side of the vertical stab in front of the rudder. Unfortunately the vortex generators were not available and the operator would have had to have them manufactured to match the original drawings so it didn't go forward with the modification. Above, Vortex generators on the fin of a B-26K, which directs dedicated airflow onto the rudder for more a responsive flying surface operation.

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