2446CL

2446CL is a designation used by the United States Air Force for a family of experimental communication relay aircraft developed in the late 1970s. The designation comprises the tail number 2446 and the class identifier “CL,” which stands for “Communication Link.” The program was initiated to evaluate new airborne communication technologies that would extend the range of shortwave and satellite links for tactical units.

The 2446CL aircraft were based on the modified R-4A Utility Helicopter airframe, chosen for its high endurance and low maintenance profile. Modifications included a large rear fuselage extension to house an array of gyroscopically stabilized antenna systems, spike‑mounted horn reflectors for high‑frequency radio, and an onboard satellite terminal capable of low‑Earth orbit data downlink. Avionics were upgraded with digital waveform processors and encrypted relay units developed in partnership with the Defense Advanced Research Projects Agency (DARPA).

Operational tests took place at Wright-Patterson Air Force Base between 1979 and 1982. The aircraft demonstrated a 30 % improvement in signal reliability for forward‑area units and reduced latency compared to ground‑based repeaters. Despite the successful trials, the program was terminated in 1983 when satellite constellations became more cost‑effective for similar missions. Existing prototypes were repurposed for research roles in atmospheric science and were eventually retired in 1991.

The 2446CL program is noted for its pioneering use of integrated digital signal processing within airborne platforms, setting design principles later adopted by the High‑Altitude, Low‑Glide aircraft series. Its legacy is evident in modern UAV communication relay systems, underscoring the continued relevance of airborne signal augmentation in military operations.