An AQM-38A preserved at White Sands Missile Range Museum.

The origins of the AQM-38 lie in the RP-70 (XKD4R-1) radio-controlled drone which Northrop developed in 1957. A purely developmental model, the drone was never produced in this form but did lead to the production of its successor. In the late 1950's, Northrop's Radioplane division developed the RP-76 a high-performance, rocket powered, radio controlled, recoverable subscale target drone, destined to be launched from the USAF's F-89 Scorpion. It was used for surface-to-air, and air-to-air missile firing practice. Like the earlier Crossbow, the RP-76 had a cigar-shaped fuselage and guidance provided by an autopilot with RC backup, but it was much smaller and was powered by a solid rocket engine, with an exhaust nozzle just behind each wing. It had a unique set of flying surfaces: shoulder mounted wings with a slight sweepback, three forward control fins underneath each side of the nose, a peculiar downward-mounted fixed horizontal "tee" tail located below the ventral vertical tail, and smaller dorsal fin.

The key structural component of the RP-76 was the steel engine case housing the solid propellant rocket motor. To this, the plastic wings, nose section, and aft fuselage were attached. The integral flight control package, including control vanes, was located in the nose section.

Main sources:
- Encyclopedia Astronautica
- Western Museum of Flight

Radioplane RP-76 / RP-78

USAF / Army designation: RP-76, AQM-38A
US Navy designation: RP-78, AQM-38B

Powerplant: 1 x 160 N (37 lb) Aerojet 530NS35 (AGM-38A)
                 1 x 440 N (100 lb) (AGM-38B)

Significant date: 1958

The RP-76 entered service with the US Army in 1959, usually launched from F-89 Scorpion aircraft as a target for surface-to-air missiles. It was powered by an Aerojet solid-fuel rocket, giving a flight at high subsonic speed for almost 10 minutes. Controlled by an automatic system in flight, the missile could also be guided by radio. The fuselage was fitted with a fixed horizontal tailplane below the tail and three forward control fins. A two stage parachute allowed it to land once the mission was completed. Radar reflectivity augmentation equipment (i.e. to increase the radar signature) included a Luneberg lens which provided reliable passive reflectivity at a minimum cost as a target for the Nike-Ajax, Nike Hercules, and Hawk missiles. The RP-76 used a Northrop RPTA-1 tracking aid system. Smoke generating and night light kits were used for visual tracking.

The RP-76 was powered by an Aerojet solid-propellant rocket engine with twin thrust nozzles canted 15 degrees outboard in the horizontal plane; this produced a thrust of 160 N (37 lb) for about 9 minutes. The drone had two rocket exhausts at the sides of the fuselage, and could reach a speed of Mach 0.94. The RP-76 was controlled in flight by an automatic control system with optional command control override by radio command, and could be recovered by a two-stage parachute system. The control vanes formed an integral part of the fuselage. Recovery was done with a three foot diameter ribbon brake parachute and a second stage 24 foot diameter ring slot main canopy were deployed at a predetermined altitude.

Beginning in 1959, the RP-76 was used by the US Army to train surface-to-air missile crews at US and Far East target ranges, mainly with the MIM-3 Nike-Ajax. Strangely enough, throughout these Air Force/Army guises the RP-76 apparently never received any designation other than its company designation until 1963, when it was redesignated as AQM-38A. The AQM-38A appears to have been largely made of plastics, and carried radar enhancement devices to simulate larger aircraft. It appears to have been replaced by the Beech AQM-37, discussed later, and was phased out in the early 1970s.

During the summer of 1960, at the White Sands Missile Range in New Mexico, an AQM-38A climbed to a height of 72,500 feet, attaining a speed of Mach 1.03 during the flight. Later, a new high performance version, designated RP-76E, attained a speed in excess of Mach 2 at an altitude of 80,000 feet. The US Navy also produced a modified version, the RP-78, which had a higher thrust rocket motor allowing supersonic speeds of up to Mach 1.25. This was used for air-to-air missile training of US Navy all-weather interceptor fighter pilots at the Pacific Missile Range, Point Magu, California. Interestingly, the Navy's RP-78 was apparently never designated as KD4R-1 (or -2) but retained its company designator, although it was clearly a production development of the XKD4R-1. The RP-78 was redesignated as AQM-38B in the 1963 reformed tri-service system. Since mid-1959, over 2,000 of the AQM-38A/B targets were ordered by the US Armed Forces.

Population: over 2000

Specs & performance:
Length: 2.95 m (9 ft 8 in)
Wingspan: 1.52 m (5 ft)
Height: 0.46 m (1 ft 6.2 in)
Diameter: 30 cm (12 in)
Empty Weight: 197 lb.
Launch Weight: 136 kg (301 lb)
Speed (AQM-38A): Mach 0.94
Speed (AQM-38B): Mach 1.25 (1,450 kph)
Ceiling (AQM-38A): 18,300 m (60,000 ft)
Ceiling (AQM-38A): 24,000 m (78,700 ft) (some give 24,400 m)
Endurance: 23 min. (powered: 9 min.)
Range (AQM-38B): 70 km (44 miles)
Guidance: Command Link
Liftoff Thrust: 45 kgf
Maximum range: 65 km
Acquisition Range in S-Band: 110,000 yds.
Tracking Radar Range in X-Band: 73,000 yds

Crew/passengers: unmanned