Origins

During World War II, American primary heavy bombers — Boeing B-17 Flying Fortress, Boeing B-29 Super Fortress and Consolidated B-24 Liberator — was very success both in European Theatre and Pacific Theatre. But they soon be replaced by in development Northrop B-35 and Convair B-36 Peacemaker. In which the B-36 was win the contract for a new bomber. Republic P-47 Thunderbolt and North American P-51 Mustang have no enough range to escort B-36, so in 1940's AMC sent out a Request of Proposal for a aircraft with piston-engined aircraft that can fit inside B-36 bomb bay. But this later was changed to jet engine. McDonnell was the only company to submit a proposal. The first design, model 27 half-exposed under the B-36, it tremendous amount of drag, making the carrier itself have shorter operational range. And it was rejected. So the team redesign it and it called model 27D, where it called McDonnell XF-85. The McDonnell team called it "Bumble Bee", but AMC team call the aircraft "Goblin" that we know until today.

Model 27D.

Design

The design have a very weird E G G shaped fuselage (but the Wikipedia says it looks like a potato), three fork-shaped vertical stabilizers plus one down below, four stabilizers in X shaped which have high dihedral to support both pitch and yaw controls and 37° foldable sweep wings. It was powered by a single Westinghouse J34 and armed by 4 M3 Browning (a modified version of M2 browning for aircraft and air support). The cockpit was so small that only a person with height under 5'8" (170 cm) can fit inside. There's no landing gear added to reduce weight so during testing, a fixed landing skid on front and spring-steel "runner" on each landing gear tip was added in case of emergency landing to save the prototype from crashing to ground. A foldable hook was placed in the aircraft's center of gravity (center of mass if you're casual JNO player) to catch the trapeze of the mother ship.

The B-29 was used for carrier since there's no B-36 was ready for testing.