On 3 December 1942, the USAAF sent out a Request for Proposals (RfP) for a diminutive piston-engined fighter.

Other late-war rocket-powered parasite fighter projects such as the Arado E.381 and Sombold So 344 were unrealized 'paper projects'. Later in World War II, the Luftwaffe experimented with the Messerschmitt Me 328 as a parasite fighter, but problems with its pulsejet engines could not be overcome. After that attack, the squadron, based in the Crimea, carried out a tactical attack on a bridge over the river Dnieper at Zaporozhye, which had been captured by advancing German troops. In August 1941, these combinations flew the only combat missions ever undertaken by parasite fighters – TB-3s carrying Polikarpov I-16SPB dive bombers attacked the Cernavodă bridge and Constantsa docks, in Romania. Starting in 1931, aircraft designer Vladimir Vakhmistrov conducted experiments in the Soviet Union as part of the Zveno project during which up to five fighters of various types were carried by Polikarpov TB-2 and Tupolev TB-3 bombers. Navy had a short-lived operational parasite fighter, the Curtiss F9C Sparrowhawk, aboard the airships Akron and Macon. The concept of a parasite fighter had its origins in 1918, when the Royal Air Force examined the viability of Sopwith Camel parasite fighters operating from their 23-class airships. The USAAF considered a number of different options including the use of remotely piloted vehicles before choosing parasite fighters as the most viable B-36 defense. Pilot fatigue had also been a problem during long fighter escort missions in Europe and the Pacific, giving further impetus to innovative approaches. The development cost for longer-ranged fighters was high, while aerial refueling was still considered risky and technologically difficult. These fighters could not match the range of the Northrop B-35 or Convair B-36, the next generation of bombers developed by the United States Army Air Forces (USAAF). The 1947 successor to the USAAF, the United States Air Force (USAF), continued to examine the concept of parasite aircraft under three related projects following the cancellation: MX-106 'Tip Tow', FICON, and ' Tom-Tom.'ĭuring World War II, American bombers such as the Boeing B-17 Flying Fortress, Consolidated B-24 Liberator, and Boeing B-29 Superfortress were protected by long-range escort fighters such as the Republic P-47 Thunderbolt and North American P-51 Mustang. The XF-85 was swiftly canceled, and the prototypes were thereafter relegated to museum exhibits. Flight tests showed promise in the design, but the aircraft's performance was inferior to the jet fighters it would have faced in combat, and there were difficulties in docking. The prototypes were built and underwent testing and evaluation in 1948. The XF-85 was a diminutive jet aircraft featuring a distinctive egg-shaped fuselage and a forked-tail stabilizer design. This was to address the limited range of existing interceptor aircraft compared to the greater range of new bomber designs. The XF-85 was a response to a USAAF requirement for a fighter to be carried within the Northrop XB-35 and B-36, then under development. McDonnell built two prototypes before the Air Force (USAAF) terminated the program. The XF-85's intended role was to defend bombers from hostile interceptor aircraft, a need demonstrated during World War II. It was intended to deploy from the bomb bay of the giant Convair B-36 bomber as a parasite fighter. The McDonnell XF-85 Goblin is an American prototype fighter aircraft conceived during World War II by McDonnell Aircraft.

Shifty by chuck yeager