Douglas A/B-26 Invader

Armament

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Military Variants - Technical Data, main page

Individual aircraft armament specifications

 
 
The Douglas A-26B Invader shined when it came to its armament, with the battery of 6 x 12.7mm (.50 caliber) heavy machine guns (early block A-26B models ) all allocated in the nose housing and the later block B-26Bs featured a total of 8 x 12.7mm nose-mounted machine guns, this allowed the Invader to make devastating strafing sweeps on enemy ground targets with destructive results, combining the concentrated power of six to eight heavy caliber machine guns into one focal burst of hot lead.
In addition to the nose armament, two 12.7mm machine guns were held in a dorsal barbette while another two were featured in a ventral barbette, which although originally designed as an aerial defensive system was found to be a substantial bonus when operated in a ground attack roll.  
Invaders could also sport 8 x underwing gun pods and 6 x 12.7mm machine guns mounted in each wing leading edge (three guns to a side) along with blister mounts on the fuselage sides - all concentrated in a forward-firing position.
With all this concentrated fire power it was surprising that the Invader was never selected to the roll of night fighter, which went to the P-61 Black Widow. 
 In total, a given A-26 could sport as many as 22 x 12.7mm machine guns with up to 6,000 rounds of ammunition.
 
 
A common practice in squadrons, was to disengage two of the eight nose mounted .50-cal's.
Firstly when all eight guns were fired, the cockpit soon became consumed with smoke and using just six would vastly reduce this.
Secondly, in order to make ramp turn arounds quicker during sorties, if any of the guns jammed or became U/S then it was easier to re engage the spare .50-cal's for ease of operations as opposed to replacing them. 

The Douglas Invader's lethality was furthermore accented by the option of carrying 4,000 internally and 8,000lbs on external pylons, in the form of drop bombs or 8 to 14 x 5" rockets (the latter held externally on eight or fourteen underwing pylons - the full 16 rocket deployment was achievable in lieu of the drop tanks and wing mounted bombs).
 
In fact, Invaders were known to be able to carry greater bombloads than that as found on the larger Boeing B-17 Flying Fortresses.
 

 

In detail:

As well as an offensive load of 4000 Ibs of bombs, the eight mounted nose guns and three guns in each wing with a total of 4000 rounds and four turret guns with 500 rpg, the A/B-26 Invader was a formidable adversary, but development of the new and much modified B-26K gave the Invader a further edge in aerial combat and allowed this old and tired aircraft to continue to operate through the Second and Korean wars to continue through Vietnam.

  • Eight mounted nose guns
  • Three guns in each wing
  •  Four turret guns ( Two remote turrets )
  • 4000 Ibs of bombs
  • The A-26A (B-26K) could carry a maximum of 800 pounds underneath the wings plus 4000 pounds internally. However, the actual load carried on combat missions was usually somewhat less in order to gain maneuverability and to reduce stress loads.
  • A typical underwing load consisted of a pair of SUU-025 flare dispensers Two LAU-3A rocket pods, and four CBU-14 cluster bomb units.
  • Later, the rockets and flares were often replaced by 500 lb BLU-23 or 750 lb BLU-37 finned napalm bombs.
  • The M31 and M32 incendiary clusters could also be carried, as well as M34 and M35 incendiary bombs
  • M1A4 fragmentation clusters, M47 white phosphorus bombs, and CBU-24, -25, -29, and -49 cluster bomb units.
  • General-purpose bombs such as the 250-lb MK-81, the 500-lb MK-82, and 750-lb M117 could also be carried.
  • During the Korean war alone, Invaders flew some 60,000 sorties Invaders were credited with the destruction of 38,500 enemy vehicles, 3700 railway cars, 406 locomotives, and seven aircraft.
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.

 
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Research and development configurations for nose armament.

  • One 75mm Cannon stbd, Two .50 MG port
  • One 37mm Cannon stbd and port
  • One 37mm Cannon stbd, Two .50 MG port
  • One 75mm Cannon stbd, 37mm Cannon port
  • One 37mm Cannon port, Four .50 MG Stbd
  • Four .50 MG stbd, 37mm Cannon port
  • Four .50 MG stbd, Two .50 MG port
  • Six .50 MG, four stbd / Two port

Another config studied was for two new design quick-firing 37mm Cannons in a ventral pack with magazines extending into the bomb-bay.

The .50Mg wing guns were introduced at the A-26B-50-DL (solid nose) and A-26C-30-DT (glass nose) production blocks.

nosesw.jpg

 
Guns - 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 - 100 lbs possible
Torpedoes/rockets: 14 - 5 inch rockets under the wings instead of bombs.
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 C-model:
500
rpg for each twin - .50 barbette
400 rpg for 2 forward nose .50's and 6 wing-mounted .50's

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 - .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).

In brief:
 

A-26 Invader Forward Firing Armament Options

Notes: Green Text indicates that nose was put into actual production; red text indicates it remained only on paper.

References:
Douglas A-26 and B-26 Invader by Scott Thompson

 

Nose Type

Armament

XA-26C
37mm

4 x M4 or X-9 37mm Cannon (32 rpg)

Bombardier Nose

2 x M2 .50 Cal MGs (400 rpg)
(Mounted on Right Side)

All Purpose Nose
Six Gun Nose

(Photo)

2 x M2 .50 cal MGs (Left) (400 rpg)
4 x M2 .50 cal MGs (Right) (400 rpg)

All Purpose Nose
Eight Gun Nose

4 x M2 .50 cal MGs (Left) (360 rpg)
4 x M2 .50 cal MGs (Right) (360 rpg)

All Purpose Nose
37mm / .50 #1

(Photo)

1 x M9 37mm Cannon (Left) (75 rpg)
4 x M2 .50 cal MGs (Right) (400 rpg)

All Purpose Nose
37mm / .50 #2

2 x M2 .50 cal MGs (Left) (400 rpg)
1 x M9 37mm Cannon (Right) (75 rpg)

All Purpose Nose
37mm
(Photo)

1 x M9 37mm Cannon (Left) (75 rpg)
1 x M9 37mm Cannon (Right) (75 rpg)

All Purpose Nose
75mm / .50

2 x M2 .50 cal MGs (Left) (400 rpg)
1 x T13E1 75mm Cannon (Right) (20 rpg)

All Purpose Nose
75mm / 37mm

1 x M9 37mm Cannon (Left) (75 rpg)
1 x T13E1 75mm Cannon (Right) (20 rpg)

Clarification

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.

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."

Other load options were

Bomb Racks

  • 3 - each side internal
  • 4 - 2 per wing external
  • 2 - 1 per wing photoflash
  • All A/C were eventually equipped with rocket launch stations.

cb45.jpg

a26weaponload.jpg

 
 
In Brief:
 
 

A-26 Invader Approved Uniform Bomb loads

References:
Douglas A-26 and B-26 Invader by Scott Thompson

Loading
Mix #

Bomb Bay

Total
Payload

1

4 x 1,000 lb

4,000 lbs

2

6 x 500 lb

3,000 lbs

3

8 x 250 lb

2,000 lbs

4

16 x 100 lb

1,600 lbs

5

2 x Mk 13 Torpedoes

4,432 lbs

6

4 x Mk 26 1,000 lb
Naval Mines

4,000 lbs

Notes: On the underside of each wing were two hardpoints designed to accept bomb racks, chemical tanks, or machine gun pods. Each rack could carry a single 100, 300 or 500 lb bomb; thus with a full wing rack loadout; four 500 lb bombs could be carried in addition to the bomb bay payload.

When used with machine gun pods, each hardpoint could carry a single pod containing a pair of M2 .50 caliber MGs, each provided with 300 rpg. Thus, when fitted with four gun pods, an A-26 had eight machine guns and 2,400 rounds in addition to whatever was fitted in the nose. (Photo of Gun Pods)

Later A-26s could carry seven 5” HVAR rockets per wing, for a total of 14.

Gun round ejections

gunnose.jpg

a268g1.jpg

a268g3.jpg

a268g2.jpg

 
Ron Lapp from Winnipeg, Manitoba Canada, sent in the above three drawings along with the narrative attached, thanks Ron.

Hi Martin,

I finally received some definitive information concerning how the expended cases and links in the solid nose 8 gun A-26B Invader were handled. I posted my question on the Yahoo A-26 forum, which you had listed on your web site, and Rick Elwood from the Pacific Coast Air Museum in Santa Rosa, CA responded that "The 8-gun nose collected spent shells and links in a canvas bag in the lower rear part of the nose. They were removed after each flight through a large access door in the bottom aft of the nose."

I asked him if he could send me the pages which covered this in the technical document that he referred to (Maintenance and Erection Manual AN 01-40AJ-2) and I recently received this excellent information.

I scanned the three pages and thought I would send them to you and you could post them in the "Drawings/Illustrations" section of your web site if you wished. I checked with Rick to ensure it was okay with him, and he gave me the green light. I am therefore enclosing the three pages from the Maintenance Manual for your information.

In the e-mail that you sent me on April 14 2008, which contained Don Vogler's comments from a B-26K armament crewmembers, it sounded like the cases and links were not collected in a bag, but rather just piled up in the nose of the aircraft under the guns. I sent Don a subsequent e-mail to try and get some further clarification, but as of yet, I have not heard from him. If I do, I will let you now.

nosegunlayout2.jpg

B-26K Gun management

Most pilots considered the gun set-up on the K as first rate.
They were newly manufactured and dependable and eight guns with a couple of thousand rounds of .50 caliber gave a lot of fire-power.
The fire control panel for the .50s was on the center overhead console, just in front of the emergency jettison handle of the clamshell canopy. The .50 cal. trigger was on the right horn of the pilot's yoke.
Guns were fired electrically, charged pneumatically. On a gun run the nav. usually charged the guns as the pilot rolled in. Coming off the target the nav. held the "gun hold-back switch" open to keep the breeches open and let the guns cool down.
Most pilots experience on the B-Model and those guns were anything but reliable. At Bien Hoa most Bs had six-gun noses. A couple had eight gun set-ups and a couple had 14 guns in the wings and nose. They were all bad when it came to fouling, jamming, cooking-off and burning out.
Every aircraft had its own history and there was no telling how old most of those guns were.
Barrels were burned-out and scrapped regularly. On strafing runs, guns would start and stop firing randomly and it was the navigators job to do a quick re-charge when itgot down to 2 or 3 guns firing.
Navigators always tried to hold the breeches open for a couple of extra seconds to get fresh air blowing into the barrels. When coming off of strafing runs it was common to have rounds cook-off long after the pilot released the trigger.
On the six-gun nose the number five and six gun was not in the nose but in the right side of the fuselage right in front of the cockpit. That put the breeches of those two guns right in front of the navigator’s knees. There was suppose be a canvas curtain separating the cockpit from the gun bay but it had usually rotted away.
When in action the cockpit was filled with smoke and cordite. generally the canvas curtain in front of the bomb bay was usually gone too, as well as other canvass gaskets and rubber canopy seals so that wind constantly roared thru the cockpit. A guy could get a chart sucked right out of his hand thru the crack in the canopy where the seal had long since rotted away. 
Some Bs had manually-charged guns. There was a panel just below the nav’s instrument panel that had six cables dangling out of it. Each of these cables had a T-handle that let the navigator manually pull open the breech on each gun.
It took a pretty good tug on each T-handle to chamber a shell and navigators were always told to charge twice.
 

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