It too as not used in USAAF aircraft during WWII...although the Bell -1 carried the AN/ARC-5 VHF set in 1947. Mike, This has probably been discussed before. Was the AN/ARC-5 VHF set in the Bell X-1 just a VHF set or did it have HF as well? Curious as to the configuration of the radios in the X-1. Thanks, Jay KE6PPF ,