F-106 Armament and Weapons

The M61 operates on the Gatling principle. 6 20-mm barrels are mounted on a geared rotor that is driven by a 20-hp electric motor. As the motor turns the rotor, the cam follower on the bolt of each rotating barrel follows a fixed cam path in the gun housing, opening and closing the bolt once per revolution. Firing only once per revolution reduces each barrel's rate of fire to below that of most single-barrel revolver cannon. GE claims that this continuous rotary motion eliminates the impact loads on gun components and that sharing the thermal duty cycle among 6 barrels "significantly" increases barrel life.  The use of external power eliminates jamming due to a misfired round.

In aircraft with the double-ended, hydraulically driven link-less feed system, rounds stored along longitudinal rails within the drum are moved to the gun end by a helix; the helix is made of Fiber-Reinforced Plastic (FRP) in the F/A-18. A rotating scoop disc assembly transfers the rounds to a rotating retaining ring. The rounds travel partway around the ring to the exit unit, which puts the rounds into the chute that feeds the gun. Empty cases are returned to the drum for storage.

VARIANTS:

Phalanx CIWS: Modified M61 for shipboard anti-missile use. Built-in pulse-Doppler J-band fire control radar, and digital computer. See separate entry.

Lightweight M61A1: Lighter weight, has linear link-less feed system, AIM-GUNS fire control software changes that expand the effective gun envelope, and PGU-28/B Semi-Armor-Piercing High Explosive Incendiary (SAPHEI) projectiles.

Sea Vulcan JM-61-MB:  M61 in open mount fitted on some Japanese maritime safety patrol craft.

M35 Armament sub-system: Mounted under the Bell AH-1G Huey Cobra's left sponson, the M35 has the XM-195 gun, which is an M61A1 gun modified with blast deflectors. The system weighs 1,168 lb (530 kg) loaded, 595 lb (270 kg) empty and carries about 950 rounds of ammunition which it fires at 4,500 shots/min.
300 M35 kits purchased beginning in 1968.

USERS/PLATFORMS (The M61 gun is in widespread use by the United States and many other nations on the following aircraft. Aircraft are listed by the country of manufacture.)

CHARACTERISTICS:

AIM-4F WSEM
WSEM Tape

WSEM:  The AIM-4F Weapon System Evaluator Missile (WSEM) is an item of test equipment that is used to evaluate the performance of the fire control system during an airborne simulated attack. This is done by permanently recording the missile preparation signals on a light-sensitive oscillogram. The signals that are recorded on the oscillogram are recorded in normal missile prelaunch time sequence as either an analog or digital trace. When the oscillogram is developed, the analysis of these traces verify the correct timing and magnitude of the signals. The prelaunch signals supplied to the WSEM may either perform the identical functions as in a tactical missile, or may be used to serve particular functions in the recording unit of the WSEM. In either case, these signals are recorded on the oscillogram.

RO-104/AJ G (MSR)
Film used from the Special Weapon Simulator, called a MSR for McDonnell Simulator Rocket.

MSR:  When installed on the F-106 aircraft, the recorder simulator RO-104/AJ G (MSR) provides a complete in-flight check, and permanent record of the presence of the preparation and firing signals normally applied to an AIR-2A special weapon during an attack run. The complete information for four passes can be recorded. The MSR is installed on the special weapon ejector rack in place of the tactical rocket. The recorded data is obtained without rocket expenditure or telemetering equipment and is available immediately upon completion of flight. The output indications, representing the presence of special weapon signals, appear as numbers and functions photographed on Polaroid-type film.  A list of the signals recorded, and the corresponding film indication, appear like this image.

ARMAMENT TEST SET (ATS)
Airman Second Class Erv Smalley, Feb, 1962, Weapons Calibration Hanger, Kincheloe AFB, Michigan.

While the WSEM gave an airborne check of the missile circuits and the MSR gave an airborne check of the rocket circuits, the attached photo of the ATS (Armament Test Set) tested the missile armament on the ground in a high altitude, high speed simulated environment known as Short System Ground Check (SSGC) # 5. The armament could also be manually tested from the 596 unit in the right main wheel well as well as the automatic SSGC # 5 test. Results were displayed on the ATS via lights and tripped circuit breakers. When necessary, successful ATS ground tests could be substituted for airborne verifications when determining qualifications for standing Alert.