Invader Weapons

The A-26B Invader had an outstanding armament load-out. In this section we'll cover all of the various ways this plane could be armed and equipped. Below are some photos showing a small fraction of weapons loadouts available.

Example Payloads

8th Bomb Squadron Armorers sit with a load of 100 pound bombs in Korea.

A Korean-war era Invader displaying a weapons load that includes Napalm, 5" rockets, and phosphorus grenades.

A Korean-War Invader showing a weapons load of 4x 500 pound bombs, 14x 250 pound bombs, and a plethora of machine gun ammo.

Nose Guns

The Invader was capable of being equipped with a wide variety of nose-mounted armament.

Cannons

Douglas experimented with several different cannon armament variations. There are several types of nose armament configurations that were shown in illustrated forms that never made it into production. Fore example, there are a lot of misconceptions that the 37MM cannon was paired with 4x Browning .50 caliber Machine Guns, but I've found no evidence to support this. The 37MM with 4 machine guns was shown in illustrated drawings, but I have not seen the 37MM cannon arranged in that particular configuration.

75MM

The first production Invaders were built with a 75mm cannon in the nose. A very small number of Invaders were actually produced at the factory with this configuration. Production block 1 (5 planes) and block 5 - Long Beach (15 planes), and Production Block 5 - Tulsa (10 planes) were built with this nose. By production block 15, the nose was altered to be a swappable "general purpose" nose. Officially there are no reports of this cannon being used in combat. Unofficially, I've heard unverified tales of at least one plane in Korea that was equipped with such a nose specifically to combat trains hiding in tunnels.

Here is the 75mm cannon on the XA-26B prototype Invader. This prototype has features that did not make it into the production version, such as the flashing around the barrel.

Here is one of the earliest production model invaders to come equipped with such a nose (41-39108).

This next photo is perhaps the most telling of what was eventually installed on the production model units. This early model Invader is equipped with the 75mm cannon, but it is lacking the 2x .50 caliber machine guns often attributed with this configuration in the pilots manual drawing. This is one of the first 20 Invaders produced, and after those first 20 came off the line, the default nose armament was changed to machine guns. Although the illustrations suggest 2x .50 caliber machine guns installed alongside the 75mm cannon, there are only a handful of photographs of this configuration actually being produced. The small hole in the center of the nose in the image below was for gunsight to allow the cannon to be aimed.

Here is another production model invader with the 75mm cannon. Note that this plane is a different plane than the one posted above. And, like that one, this one is also lacking the 2x .50 caliber machine guns shown in the illustrations.

75MM & 37MM

Douglas experimented with several different cannon combinations. One of the variants that they produced in very limited quantities was a 75MM cannon paired with a 37MM cannon.

Here is that same plane from the side. This photo is sometimes misreported as having a 4x Browning .50 caliber machine guns on the right side, but the photo above clearly shows that not to be the case.

37MM & 37MM

One of the nose configurations that was available was twin 37MM cannons. This configuration was tested on at least 1 production model variant.

This photo shows a production model Invader equipped with twin 37MM cannons.

105MM

There is evidence to suggest that at least 1 Invader was equipped with a prototype 105MM cannon in the nose. There is a single drawing showing this gun in a similar fixed position in the nose as the 75MM version. The source record states that it was the largest forward firing cannon ever shot from a plane, which does suggest that it was at least test-fired. Normally, I wouldn't put too much stock into a single report, but this report comes from "The Machine Gun, Volume 5". This book was written by Col. George M. Chinn, USMC (Ret), who was the United States' foremost weapons expert during and after WWII. He has been called the "Bill Gates of Machine Guns" and this work was the culmination of his life's work. Given who it was that reported this gun, I am inclined to believe him.

I have been looking for the records of this project, but so far, I have not had much luck. Unfortunately, the Air Force didn't label top secret test projects with easy names like "105mm Canon Test", so I do not even know what name to search for.

Newly uncovered documents show that this weapon was indeed fired at least 50 times using a variety of different ammo loadouts spread out across two different flights. The tests were conducted in California, and Floyd A. Thomas was the gunner who volunteered to fire the cannon during the tests. The tests were concluded by Jul 1945.

In the meantime, I have been able to narrow down that this type of cannon was most likely a variant of the T12 Aircraft Howitzer.

20MM

The 20MM cannon is a largely unknown armament carried on the Invaders. It was not standard equipment and is not listed in any of the Invader books or manuals. I discovered that the 20MM cannon was used during the Korean War as part of a secret test project. In scouring over the historical records of the 13th Bombardment Squadron the monthly report for July, 1951 shows that one Invader was equipped with a 20MM cannon. It was originally a 6-gun nose variant. The last/outermost two .50 caliber guns on the Navigator's side was replaced with the 20MM cannon as well as both .50s on the pilot's side. This plane had 2x .50 caliber machine guns and 2x 20MM cannons. It is not clear at this point if the other squadrons in the 3rd Bombardment Group had similar planes as well.

From the records of the 13th Bombardment Squadron it was evident that the plane was used fairly extensively. The squadron expended between 2,000 and 2,5000 rounds of 20MM ammo every month until March 1952 when the 20MM ammo disappears from the report. The plane with the cannons was lost in action in Jul 1952.

Machine Guns

The Invader featured many different configurations of machine guns during its service lifetime. With a single burst of the all machine guns, the entire aircraft would buffet violently rearward, a consideration for the crew to keep in mind in terms of their own safety. In total, at maximum configuration, a given A-26 could be equipped with as many as 22x .50 caliber machine guns with up to 6,000 rounds of ammunition.

6-Gun

By production block 15 the "general purpose" nose was put into place. It could, as the mission required, but swapped out for a different nose in the field. The standard configuration for the general purpose nose was a 6x .50 caliber machine gun arrangement. This gun configuration was the most prolific version produced.

Two unknown crew members of the 416th Bomb Group loading a WW2 hard-nose Invader's Browning M-2 Machine Guns at Laon/Athies in early 1945.

8-Gun

Later production B-26Bs featured a total of 8x .50 caliber nose-mounted machine guns. This assembly allowed the Invader to make devastating strafing sweeps on enemy ground targets with usually destructive results, combining the concentrated power of the heavy caliber machine guns into one focal burst. By the time this configuration made it into deployment World War II was almost over and this version saw little use in combat. It was, however, heavily used in the Korean War.

An armament technician loads an 8-gun Invader in Korea.

14-Gun

As World War II progressed Douglas continued to find ways to increase firepower. They experimented with an arrangement that would have allowed 14x .50 caliber machine guns to be fitted in the nose, however, this version never made it into production. Although this nose was being tested, it is unclear how it would be received in the field. Plane crews reported that firing all 8 of the 8-gun nose machine guns resulted in smoke filling the cockpit. To combat this, many crews would disengage or remove two of the guns, which cut down on the smoke and allowed the plane to have a couple of spares if they needed them.

Turrets

In addition to the nose armament, two .50 caliber machine guns were held in a dorsal turret, and two more .50 caliber guns in the ventral turret. These turrets had an excellent range of motion. Each one could rotate 360 degrees, could depress 5 degrees, and could raise a full 90 degrees. Between both of the turrets the plane could protect itself from an attack in any direction.

This photo shows the upper turret with the outer cover removed. The twin Browning .50 Caliber machine guns are clearly visible. Also of note in this photo are two strange bubbles in the glass of the gunner's compartment. I believe this was an experiment to improve the gunner's visibility. Whatever the case, this is the only photo I have ever seen of these bubbles. This view is from the front of the plane looking toward the back.

Here a 13th Bomb Squadron Gunner, Freddie Carroll, inspects the upper turret on an Invader in Korea.

The upper turret is pictured below.

Here is another view of the upper turret. This is from the tail of the plane looking forward. You can see an antenna, then the gunner's periscope lens, the gunner's escape hatch, and then turret itself.

Invaders that were supposed to go to the 5th Air Force in the Pacific had the ventral turret removed in favor of an additional 125-gallon fuel tank. The Ventral Turret is pictured below. The gunner's periscope sight can be seen in the glass bubble.

These photos shows the gunners periscope. The seat was directly attached to the post and could swivel 360 degrees.

Wing Guns

Gun Pods

Invaders could also be equipped with underwing gun pods. Each pod carried 2x .50 caliber machine guns, allowing the plane to carry an additional 8 machine guns, in addition to the nose guns.

The ammo for the underwing gun pods was stored in an ammo box inside of the wing. This photo shows two ground crew members of the 319th Bombardment Group loading the internal magazine for the underwing gun pods.

Sometimes the war didn't allow for conventional or intended configurations of the weapons systems. For example, in cases where supplies were scarce some planes were equipped with fewer guns, as is the case with 43-22321 of the 416th Bomb Group. It is one of several planes in that unit to use only 1 gun in the underwing pods.

Wing Guns

Later production models discontinued the use of the underwing gun pods in favor of 3 internally mounted .50 caliber machine guns in each wing's leading edge (for a total of six), all concentrated in a forward-firing position.

Here, Marvin Lutnesky, an armament technician for the 728th Bombardment Squadron, 452nd Bombardment Group adjusts the firing mechanisms for the internal wing guns on a plane in Korea.

The pilots had a heads-up display (HUD) that included a gun-sight that would allow them to fire the nose and wing guns directly. The gunner would only operate the turret guns. This HUD is from the A-26K Counter Invader model that was flown in Vietnam.

Bombs

The Douglas Invader's lethality was further accentuated by the option of carrying between 4,000 and 6,000lbs of internal and external ordnance in the form of drop bombs or rockets. In fact, Invaders were known to be able to carry greater bomb-loads than the larger Boeing B-17 Flying Fortresses. Endurance could be extended with the addition of 165-gallon underwing drop tanks, increasing the aircraft's range by up to 300 miles.

Some of the standard loading mixes during the end of World War II included the following:

Mix #1 - 4x 1,000 lb - 4,000 lbs total
Mix #2 - 6x 500 lb - 3,000 lbs total
Mix #3 - 8x 250 lb - 2,000 lbs total
Mix #4 - 16x 100 lb - 1,600 lbs total
Mix #5 - 2x Mk 13 Torpedoes - 4,432 lbs total
Mix #6 - 4x Mk 26 1,000 lb Naval Mines - 4,000 lbs total

During the Korean War the loadouts changed to suit mission needs. One common loadout was: 10x 500 lbs bombs (6 in bomb bay, plus 2 under each wing) - 5,000 lbs total.
16x 250 lbs bombs (in bomb bay) + 2x 500 lbs under each wing - 5,000 lbs total.

The Korean War also saw use of Napalm and Rockets, which changed the bomb loadout significantly.

2 Invaders drop 500 pound bombs on the Siegfried Line over Germany in 1945.

3 Invaders from the 13th Bombardment Squadron drop the first salvo of bombs during the opening of the Korean War.

An Invader from the 3rd Bombardment Group drops a napalm bomb on enemy ground forces during 1952.

This photograph shows an Invader from the 13th Bombardment Squadron being loaded with "blue devil" training bombs at Yokota Air Base, Japan in July, 1948.

During the Korean War the Invaders flew a lot of night missions. During those times flares would be fired over the target area to illuminate the ground so the bombers could make a clean hit. Armorer Marvin Lunetsky loads flares onto a plane before a mission. A 500 pound bomb hangs behind him.

All invaders also had a Mk33 bombsight in the gunners compartment, near the bomb bay. This bombsight could allow the Invaders to drop bombs even without a glass-nosed Invader to mark the target.

Rockets

The Invader could carry between 8 and 14x 5" AR, HVAR, or 6.5" ATAR rockets held externally on underwing pylons. They could carry as many as 16 rockets if they traded out the fuel drop tanks or wing mounted bombs. They could also be equipped to carry 12x 4.5" M8 rockets in launchers under the wings. Alternatively, they could be fitted with the 2.5" Sub-Caliber Aircraft Rocket (SCAR) which was used as a training rocket.

Invader 44-34538 "Feeding Frenzy" showing an array of missiles on the wings.

Invader 44-34244 Showing the High Velocity Aircraft Rockets (HVAR) that were common on Invaders. A loadout of 7 rockets per wing was fairly standard.

Invader 44-34563 showing a loading including a Napalm bomb, 2x 5" High Velocity Aircraft Rockets (HVAR) on the outside, and 2x 6.5" Anti-Tank Aircraft Rockets (ATAR) on the inside.

This illustration shows the launching system for the aircraft rockets that were common on Invaders.

A 13th Bomb Squadron Invader (Tail Letter W) is being equipped with training Rockets prior to a mission at Yokota Air Base, Japan in July, 1948. Note how skinny these rockets are compared to the standard 5" rockets pictured above. These training rockets are 2.5" Sub-Caliber Aircraft Rockets (SCAR) and helped pilots learn targeting and firing.

A 3rd Bombardment Group Invader conducts a rocket attack against a rail yard at Iri, South Korea in September, 1950.

Although not commonly used, the Invader was capable of carrying the M8 Rocket system. The M8 Rockets were small 4.5" inch rockets pictured here.

The M8 Rockets were fired out a T-30 Rocket Launcher, pictured here. Although these photos are from an A-20 Havoc, the same launcher system could be equipped on an Invader in the same configuration.

Torpedoes

According to the Official Pilot Training Manual for the A-26 Invader, published by the Army Air Force Office of Flying Safety, the Invader could carry 2 standard torpedoes in the internal bomb bay, released by the same button that drops the bombs. Although capable of this feature, it was never used in combat. The majority of the Invaders that were earmarked for the Navy were cancelled due to World War 2 ending. When the Navy did acquire Invaders in the post-war period they were used as utility planes for towing targets. The following two illustrations show a torpedo coming from the Invader comes directly from the Pilot Manual.

Page 61 of the Pilot Training Manual describes the Invader's torpedo capabilities:
"A single-station panel is provided between the forward and aft bomb bays to carry two torpedoes. The A-26 is an extremely versatile offensive weapon. It has tremendous strafing firepower. It can bomb from various altitudes down to skip bombing, and it can launch torpedoes. But remember, although there are 24 bomb stations altogether, only 16 of those stations can be used at any one time."

Further instructions are found on page 62:
"Torpedo Stations: Two torpedoes may be loaded as alternate armament. When torpedoes are carried, the bomb rack panels and the removable portion of the front bomb bay rail are removed. The bomb bay doors must be left open. Release your torpedoes electrically by the bomb release button with your torpedo circuit switch ON. Salvo your torpedoes manually with the bomb control salvo lever (or switch in some models)."

Glass Noses

The glass nosed Invader was designed to be a guide to pinpoint bombing targets for other bombers in the group. Later versions of glass-nosed Invaders were sometimes converted to photo-reconnaissance versions that gathered intelligence. The primary feature of the glass-nosed Invaders is a bombsight that the bombardier-navigator would use to sight the target. Several different versions were used, but the Norden Bombsight (also used in the B-17 was the most common).

This Black & White view of the Norden Bombsight shows an often overlooked but essential part of the glass nose. To the right of the bombsight is a trapezoidal panel. This panel is a hatch that opens in which allows the bombardier to clean the exterior of the glass during flight. If the plane nose becomes covered with mud, dirt, or soot the bombardier wouldn't be able to see the target.

The official documentation from Douglas shows illustrations that suggest that the glass nose C-model bombers were outfitted with 2x Browning .50 caliber machine guns in the nose. In production, that version of the glass nose, looks like the one outfitted on 43-22609.

In practice, the vast majority of planes with the guns in the nose had them removed because the noise was too bad for the navigator. This example, 43-22509, of the 386th Bomb Group still shows the patches where the guns were removed.

Starting with Production Block 40, 44-35558, the longer panel on the navigator's side was removed and panels were even on both sides of the plane.