This monster inline engine is a rarity. The 12-cylinder Franklin was used as the powerplant for the Interstate XBQ-5 drone. The Franklin was built by Aircooled Motors at the end of the Second World War. The concept for the XBQ-5 was a radio-controlled, twin-engined, mid-wing monoplane that would carry a 2,000 pound payload. A rudimentary "cruise missile" concept, the payload could be a bomb, torpedo or depth charge. Before the drone was built, the program was cancelled by the USAAC. The U.S. Navy picked up the Franklin engine to power its own drone program, the XTD2R-1. Before that drone came to production with Interstate, the Navy called for a change in powerplants from the Franklin to the Wright R-975 radial. The switch from inline to radial led to a change in the designation into the XTD3R-1.