RADIOPLANE RP-54D 'Crossbow'

US Air Force designations: (X)B-67, (X)GAM-67

Powerplant: 1 x 4.41 kN (450 kgp/1000 lb) Continental J69-T-17

First flight: July 1956

In the late 1940s, the Radioplane Company developed a set of prototypes of the Q-1 target series, which used pulsejet or small turbojet engines. In the early 1950s, the U.S. Air Force had a requirement for a missile to home in on and destroy enemy ground radar systems, and in 1953, just after the Northrop takeover (and before the subsequent renaming as the Northrop Ventura division), the company received a development contract as project MX-2013. Although the Q-1 subscale target drone series was not put into production, it was further evolved into the new Model RP-54D Crossbow anti-radar missile for the USAF, which was a derivative of the YQ-1B , and was initially designated XB-67. This was changed to XGAM-67-RP in 1955 when the USAF abandoned the use of aircraft designations for guided missiles. The GAM-67 was also designated as Weapon System WS-121A by the Air Force.

The XGAM-67 was a small turbojet-powered vehicle with straight wings and a twin vertical tail. It had a cigar-shaped fuselage, straight wings, a straight twin-fin tail, and an engine inlet under the belly. It was powered by a Continental J69 turbojet, which was a French Turbomeca Marbore II engine built in the US under license, with 4.41 kN (450 kgp / 1,000 lbf) thrust. One noteworthy feature was that only the left vertical fin had a movable rudder. The missile was air-launched from large bombers' underwing pylons; two Crossbows could be carried by a Boeing B-50 Superfortress bomber, while four Crossbows could be carried by a Boeing B-47 Stratojet bomber. The first successful powered flight of an XGAM-67 prototype occurred in July 1956, and the first guided flight succeeded in May 1957.

For its intially planned role of anti-radar missile, the Crossbow was equipped with a passive multiple-frequency radar seeker. Once the target was detected, the missile dived on it at near sonic speed, and the warhead detonated on impact. At one time it was proposed to arm the GAM-67 with a 40 kT W-31 nuclear fission warhead. In-flight control was by an autopilot and a radio-command guidance system. However, the GAM-67 was soon reconfigured as a high altitude ECM target drone to jam enemy radars. In the ECM decoy configuration, the GAM-67 would transmit radar jamming signals to confuse enemy defensive radar systems. The carrier aircraft would launch one or more Crossbow's and the resulting radar jamming would allow the bomber force to (theoretically) penetrate to the target area.

The GAM-67 was then tested as a battlefield surveillance or electronic countermeasures drone; as a battlefield surveillance vehicle, the Crossbow was launched for a reconnaissance mission over heavily defended areas or locations where time critical reconnaissance was needed and no traditional reconnaissance aircraft were available or suited to the particular reconnaissance target. With a range of only 300 miles and endurance of about 30 minutes the Crossbow was usually flown against a single target area. Recovery of the drone was done with parachutes. Once over the recovery area, a drag chute was deployed and once slowed sufficiently, a large parachute opened. Inflatable plastic cushions stored in streamlined underwing containers deployed before landing to lessen the ground impact forces. Eventually, the GAM-67s ended their careers as standard pilotless decoys.

On May 5, 1954, the Air Materiel Command assigned Ogden Air Materiel Area (based at Hill AFB) to be the prime maintenance depot for the GAM-67 air-to-ground missile. Budget cuts led to the demise of this weapon and Ogden’s responsibility for it ceased in April 1957. Only 14 were built before the program was cancelled in July 1957 because of technical and funding difficulties, in favor of a more sophisticated Weapons System designated WS-121B Longbow Anti-radiation Missile. Beginning the the late 1950s, the GAM-67 was replaced by more efficient single purpose drones like the Boeing GAM-72 "Quail" decoy and the Teledyne Ryan "Firebee" (AQM-34L) reconnaissance vehicle.

Population: 14 [54-2960/2967, 55-3466/3480 (some probably cancelled), -2969/2970, -3090,3092,3094 sait to be all cancelled,

NOTE: GM-54-2962 preserved at Valle/Grand Canyon Airport and 54-2965 preserved at Banning City Airport.

Specs:
Wingspan: 3.86 m (12 ft. 7.8 in.) — some give 3.81 m (12 ft. 6 in.)
Length: 6.10 m (20 ft. 0.2 in.) — some sources give 5.82 m (19 ft. 1 in.)
Height: 1.52 m (5 ft.) — some sources give 1.37 m (4 ft. 6 in.)
Loaded weight: 1,220 kg (2,700 lb.)
— some sources give a 1270 kg (2800 lb) weight
Launch scheme: RATO booster or air launch
Recovery scheme: parachute
Guidance system: autopilot with radio control backup
Armament: XW-7 warhead planned, not tested

Performance:
Maximum speed: Mach 0.86 — or 1,090 km/h (675 mph / 587 kt)
Service ceiling: 12,200 m (40,000 ft.)
Range: 480 km (300 miles / 260 naut. miles)
Endurance: 30 min

Crew/passengers: unmanned