U.S. Ground/Air Launched Rockets

(Updated 29 March 2014)

General Notes on US Rocketry Research in WWII:

German R&D work first began with spin stabilized rockets, while US/British research concentrated first on Fin-Stabilized Rockets. US Spin-Stabilized work began in 1943 with the team of CIT/Army Ordnance working on it – originating from a May 1943 proposal for a rocket with a 10,000 yard range – this required much improved dispersion over earlier fin stabilized types. The original 3.5” SSR developed (to match a 75mm Pack Howitzer in punch) failed to meet range/dispersion goals and caliber was increased to 5 inches.

The big difference in Fin vs Spin Stabilization is accuracy – when launched at zero or low airspeed (from ground or from a surface craft), fin stabilized rockets have poor accuracy. However, in air launched applications, the aircraft’s air-speed ensues good stabilization at the moment of launching; as shown in the following list below:

Average Cannon/Gun: 1 mil or less dispersion
Fin Stabilized Air Launched:
6 to 8 mil dispersion
Spin Stabilized 4.5" Ground Launched: 20~ mil dispersion
Fin Stabilized 4.5" Ground Launched:
20 to 40 mil dispersion

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
Eugene Slover’s Ordnance Pages
Naval Weapons of World War Two by John Campbell

USMC Rocket Detachments (Provisional)

Five units [1st through 5th Rocket Detachments (Provisional) ] were formed in 1944 and equipped with 12 International 1-ton 4x4 trucks each modified to hold three 4.5” Mark 7 Rocket Launchers, each launcher having a 12 round magazine. The Detachments were split into two equal sections and they provided concentration of fire for special needs by being attached to individual Marine Divisions.

(At Iwo, the 1st Provisional Rocket Detachment supported the 4th Marine Division, while the 3d PRD supported the 5th Marine Division).

They were used on Guam, Saipan, Tinian, Iwo Jima and Okinawa – where they endured a love/hate relationship – the troops loved the fire support they got, but hated the fact that the Rockets drew Japanese counter-battery fire in droves. Finally, in July 1945, they were redesignated “Rocket Platoons” with the same organization and made part of Marine Division HQ.

(Rocket Detachment Firing at Iwo Jima)

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.

1945 White Phosphorous Rocket Note

During the latter part of 1943, a means was developed to plasticize white phosphorous which gave it considerably higher smoke screening and anti-personnel effect. Filling of 4.5" rockets with plasticized WP began in March 1945, with the Amphibious Forces requiring 10,000 rockets per month.

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.

3.5” Navy ASW Rocket

Weight: 55~ lbs
Warhead Mass: 20 lb solid steel head
Velocity: 1,175 ft/sec

Notes: Could penetrate U-Boat pressure hulls through 50 feet of water early on and in later versions down to 130 feet. First used by aircraft on USS Block Island in January 1944.

4.5” Navy Beach Barrage Rocket (BR)

(Illustration)

Used in the following weapons:

T44 MRL (120 Rockets) – Issued for installation of the cargo space of a 2.5 ton DUKW-353, or the cargo space of a LVT Mk IV. Used USN Fin Type Rockets. (Photo)
T45 ARL (Navy Mark 7) (12 Rockets) Weight approx 157 lbs. Issued for installations on LVTs, trucks and ground firing. Fed automatically via gravity and fires rockets before reloading. (Photo)

References:
TM 9-394 4.5 Inch Rocket Materiel For Ground Use (7 February 1945) (21.9~ MB PDF)

4.5" M8 (T12) Fin stabilized Rocket:

Length: 33.19 inches
Weight: 38~ lbs
Warhead Weight: 4.3~ lbs of TNT
Muzzle Velocity: 900 ft/sec
Dispersion: 50% of all rounds fired at maximum range will fall within 65 yards by 130 yards
Maximum Range: 4,500 yards
Fuzes Authorized: PD Rocket Fuze M4A1 with 0.1 second delay for ground use and 0.015 second for aircraft use.

Notes: Hits with effect similar to 105mm HE M1 Shell. The first forward firing of a rocket from a US plane in flight took place on 6 July 1942 using early production rounds. By the winter of 1943-44, the AAF was using M8s from cluster launchers against Japanese troops in Burma.

The following variants were developed:

(Illustration)
(Drawing)

Used in the following weapons:

T27 MRL (8 Rockets) – 823~ lb total weight. Trial evaluation in combat with 12th FA Battalion at the Siege of Brest in the summer of 1944. Unsatisfactory. (Photo)
T27E1 MRL (8 Rockets) – 823~ lb total weight. Airborne version which could be broken down into two-man loads with each load not exceeding 120 lbs in weight.
T27E2 MRL (24 Rockets)
T32 Xylophone MRL (8 x 4 MRL on a 2.5 ton truck) -- 75 launchers issued to 18th FA Bn who first used them in November 1944 against the Siegfried Line. They then used them in action until 17 December 1944.
T34 Calliope MRL (60 Rockets) – Tank mounted launcher for M4/M4A1/M4A2/M4A3/M4A4/M4A6 medium tank. Controlled in elevation and azimuth with the same controls used for the 75mm gun in the turret. Fired electrically and the entire assembly can be jettisoned at will through hydraulic controls within the turret. The 75mm gun cannot be fired while the launcher is mounted on the tank due to the gun being connected to the MRL via an elevating strut. Tubes made out of fiberglass. Weight approx 1,800 lbs.
T34E1 Calliope MRL (60 Rockets) – Same as the T34, but the tubes are made out of magnesium; and the elevating strut is redesigned to allow use of the 75mm gun while the launcher is mounted. Weight approx 2,000 lbs.
T36 MRL (8 Rockets) – Can be fired from the ground or on a Jeep.
Scorpion MRL (144 Rockets) (DUKW PTO)
M12 RL (Single Shot Rocket Launcher) – Smoothbore Plastic tube weighing 22 pounds empty and 60 pounds complete with rocket and tripod. Overall length of 4 feet. Can be carried via packboard or shoulder sling. (Photo)
M12E1 (Re-loadable Single Shot Rocket Launcher)

References:
The Encyclopedia of Weapons of World War II edited by Chris Bishop
US Field Artillery of World War II By Steven Zaloga
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
TM 9-394 4.5 Inch Rocket Materiel For Ground Use (7 February 1945) (21.9~ MB PDF)
TM 9-395 4.5” Aircraft Rocket Materiel (12 September 1944) (1.9~ MB PDF)
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

4.5" M16 (T38E3) Spin Stabilized Rocket:

Length: 31 inches
Weight: 42.5 lbs
Warhead Weight: 5.3 lbs TNT
Maximum Velocity: 830 feet per second at 70 feet from launcher.
Maximum Range: 5,300 yards
Dispersion: 8 mils

Notes: Development of the 4.5" Spinner began in late 1943. Approved April 1945. VT Fuzes were developed for these rockets, but the war ended before they could be used in combat.

(Illustration)

Used in the following weapons:

M12A1 RL (Single Shot Rocket Launcher) – Smoothbore Plastic tube weighing 22 pounds empty and 64 pounds complete with rocket and tripod. Overall length of 4 feet. Can be carried via packboard or shoulder sling. (Photo)
M12E2 RL (Re-loadable Rocket Launcher) – Smoothbore Magnesium tube weighing 22 pounds empty and 64 pounds complete with rocket and tripod. Overall length of 4 feet. Can be carried via packboard or shoulder sling. (Photo)
T66 Honeycomb MRL (24 Rockets): Weighed 1,200 lbs. Deployed experimentally in the final weeks of the European War. Used at least once in Czechoslovakia against the remnants of a Panzer division dug in at the edge of a woods. From 4,670 yards, three T66s threw 71 rounds in 15 seconds "for good effect".
Five rocket battalions equipped with this weapon were organized in 1945 -- each battalion was equipped with 36 Honeycomb launchers. One of them was forward deployed to Okinawa and another to the Philippines; but the war ended before they could be used against Japan.
T72 Hornet's Nest MRL (60 Rockets): Replacement for the T34 Calliope on Shermans.
T99 MRL (44 Rockets): Replacement for Calliope for M26 Pershing. Two launchers, one on each side of the turret.

References:
US Field Artillery of World War II By Steven Zaloga
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
TM 9-394
4.5 Inch Rocket Materiel For Ground Use (7 February 1945) (21.9~ MB PDF)

4.5” M20 Spin Stabilized Rocket

Notes: Variant of the 4.5” M16 Rocket for use in single shot expendable rocket launchers. Approved May 1945.

Super 4.5 Rocket (115mm Aircraft Rocket)

Length: 72 inches
Weight: 103 lbs
Warhead Mass: 40 lb
Maximum Velocity: 1,000~ fps relative to aircraft launch velocity.

Notes: Design established December 1944 and procurement was initiated by Army Ordnance, but war ended before it could be used in combat. The SAP head of one version could penetrate 5" of RHA, while the HE FRAG head version carried 8.5~ lbs of HE or almost twice the amount of the M8 Rocket.

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.

5" FFAR

Weight: 90~ lbs
Velocity:
875 ft/sec relative to aircraft launch velocity.

Notes: Developed from the earlier 3.5” ASW Rocket by mating a 5” caliber warhead to the 3.5” rocket motor. First used in combat around December 1943. In the Pacific, the first US Navy FFARs fired were done by VMTB-134 “Rockettes” on 15 February 1944 against Rabaul. The squadron had received the rockets on 8 February 1944, and they were fired after three days of quick training!

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.

5" HVAR “Holy Moses”

Length: 72 inches
Weight: 140 lbs
Maximum Velocity: 1,375 fps relative to aircraft launch velocity.

Notes: 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.

(A-26 Invader with 14 x HVAR under the wings)

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
Naval Weapons of World War Two by John Campbell

7.2” Rocket, H.E. T14

Muzzle Velocity: 920 ft/sec
Maximum Range: 6,000~ yards

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

7.2” Rocket, H.E. T15

Weight: 70~ lbs
Minimum Range: 500 yards

Notes: Similar to T14, but with chemical head instead of HE Head.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

7.2” Rocket, H.E. AT, T16

Notes: Similar to T14, but with HEAT warhead.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

7.2” Rocket, Chemical, T21 (aka 7.2” Demolition Rocket Family)

Length (with fuze): 47.127 inches
Diameter:
7.2 inches
Weight of Warhead:
29.46 lbs, of which 20 lb is gas/chemical agent
Weight of Motor:
20.54 lbs (with 5.74 lbs of propellant)
Total Weight:
50 lbs
Muzzle Velocity:
600 ft/sec
Range:
3,500 yards

Notes: Modified version of “Mousetrap” 7.2” ASW Rocket for use against ground targets.

(Drawing)

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

7.2” Rocket, HE, T37 (aka 7.2” Demolition Rocket Family)

Length (with fuze): 36 inches
Diameter:
7.2 inches
Total Weight:
61 lbs
Warhead Weight: 32 lbs of Plastic Explosives
Muzzle Velocity:
170 ft/sec

Notes: Modified version of “Mousetrap” 7.2” ASW Rocket for use against ground targets.

Used on:

M17 “Whiz-Bang” (T40) MRL (20 Rockets) – Attached to M4-series Medium tank and aimed via turret and gun movement. ½” thick armor on the sides of launcher protected the rockets inside against .30 caliber ammunition. Unpopular with crews as the launcher prevented turret hatches from being opened. Weighed approximately 4,615 lbs empty.
T64 MRL – Modified version of M17 for Armored Engineer Vehicles.
T73 MRL (10 Rockets): Protected on front and sides by 1” armor, and ½” armor on the top and bottom; allowing protection against .50 caliber gunfire. Weighed about 4,000~ lbs.
Tx “Grand Slam” MRL (24 Rockets) – Attached to M4 Medium tank and aimed via turret and gun movement.
MK 21 “Woofus” MRL (120 Rockets) – Used on LCT(R)s. First saw action in the invasion of Southern France in August 1944.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
TM 9-296:
7.2 Inch Multiple Rocket Launcher M17 (9 January 1945) (6.7 MB PDF)

8” Rocket

Notes: Consists of a 100 pound bomb attached to a M8 4.5” rocket motor via an adapter.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

10” Rocket, HE, T10

Length: 53 inches
Total Weight:
210 lbs
Warhead Mass: 117 lbs, of which 77 lb is TNT
Muzzle Velocity:
440 ft/sec
Range: 2,200 yards

Notes: Can be filled with HE or Chemical filler as needed.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

10” Rocket, HE, T10E1 (High Velocity)

Total Weight: 190 lbs
Warhead Mass: 68 lbs, of which 40 lb is TNT
Muzzle Velocity:
1,050 ft/sec
Range: 5,000 yards

Notes: Higher Velocity version of T10.

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

10” Rocket, HE-AT, T10E2

Total Weight: 180 lbs
Warhead Mass: 35 lb TNT Hollow Charge HEAT

References:
OS 9-69 Rockets and Launchers, All Types (February 1944) (10.9 MB PDF)

11.75" Rocket, Tiny Tim

Length: 123 inches
Diameter: 11.75 inches
Weight: 1,284 lbs
Warhead Mass: 590 lb SAP, of which 150 lbs is HE
Motor Mass: 146~ lbs of propellant
Velocity: 810 ft/sec above that of launching aircraft
Range: Accurate out to 4,000 yards
Penetration: 3 to 4 feet of reinforced concrete

Notes: At a meeting on 2 February 1944, the preliminary specifications were agreed upon for "a really big rocket" -- motor tube approx 12" in diameter, a propellant charge of four 40 pound motors, and a total weight of approximately 1,200 lbs. By late April 1944, a complete rocket had been fired.

In August 1944, a test drop of a Tiny Tim killed a test pilot, causing a slight delay in development of the missile. The solution to the test drop problem was to have the rocket be released from a rocket rack and ignited by means of a 8-foot lanyard. This meant that accuracy was of course, quite poor.

The F4U, F6F and PBJ were qualified to operate the Tiny Tim – VMB-612 on Okinawa had modified PBJ-1Js capable of carrying two Tiny Tims, one on each side on the fuselage above the bomb bay doors, and flew 10 missions with them between 21 July 1945 and 14 August 1945.

(VMB-612 PBJ-1J Mitchell with Tiny Tim)
(PBJ-1J with Tiny Tim on Iwo Jima)
(PBJ-1J Tiny Tim Launch Sequence)
(F6F Hellcat with Tiny Tim)

References:
U.S. Rocket Ordnance, development and use in World War II, US GPO, 1946.
Naval Weapons of World War Two by John Campbell

M18 (T90) “Improved Bazooka”

Weight: 10.3 lbs
Length: 60.5 inches
Effective Range: 300 yards
ROF: 10 RPM

Notes: Type Classified April 1945 and produced by General Electric. Used aluminum to reduce weight over the M9. 500 had been produced when V-J Day resulted in all contract cancellations.

References:
The Bazooka by Gordon L. Rottman