Aviation History

These photos show why the XF-85 Goblin “parasite” fighter was the most bizarre aircraft ever built

The McDonnell Aircraft Corp. developed the XF-85 Goblin “parasite” fighter to protect B-36 bombers flying far beyond the range of conventional escort fighters.

The McDonnell Aircraft Corp. developed the XF-85 Goblin “parasite” fighter to protect B-36 bombers flying far beyond the range of conventional escort fighters. The “parent” B-36 would carry the XF-85 within a bomb bay — if enemy fighters appeared, the Goblin would be lowered on a trapeze and released to combat the attackers. Once the enemy had been driven away, the Goblin would return to the B-36, reattach to the trapeze, and be lifted back into the bomb bay.

McDonnell XF-85 Goblin at the National Museum of the United States Air Force.

As the pictures in this post show, the Goblin was quite odd.

‘Yes, this was a real design. No, it wasn’t a scale model. This was the full scale, actually flying version,’ says Michael Perkins, an aviation expert, on Quora. ‘Less than 15 feet in length, just 21ft wingspan, and with a maximum weight of only 5,500lbs. Armament was equally light, just four .50 machine guns.

To fit inside the parent aircraft’s bomb bay, the XF-85’s wings folded up.

‘This wasn’t designed to be a ground fighter, though. It was designed to be carried by a much larger aircraft, the massive Convair B-36 bomber and the proposed Northrop B-35 flying wing, as point-defence fighters. There were no fighters capable of escorting these bombers through enemy territory, so the theory was that the bombers would carry their own air defence, and if threatened they would launch these dinky mini-fighters that would be fast and manoeuvrable enough to at least prevent the enemy from attacking the more valuable bombers, and then when the threat was passed they would hook up to a trapeze-line retrieval system under the bomber’s belly and be drawn back up into their storage bays.’

Two test aircraft were ordered in October 1945, and flight testing with a modified B-29 began in 1948. Test pilots could successfully launch the XF-85, but the turbulent air under the B-29 made recovery difficult and hazardous. 

Although the XF-85 handled well, the test pilots reported that the airflow around the parent aircraft made it difficult to attach the hook to the trapeze.

Perkins continues;

‘Although the plane flew, and showed fairly decent handling in the normal flight envelope, the attempts to re-hook with the parent bomber were all failures and the test plane had to make belly-landings (they were so small and light they weren’t even fitted with landing gear). It was also slower, less manoeuvrable, and much less heavily armed than the new Soviet fighters coming through that it would be expected to combat, so this combined with the failure of the docking concept and when aerial refueling of conventional fighter aircraft showed greater promise led to the cancellation of the program in 1949, just four years after the first proposals were made and after just two years of on-off flight testing.’

No XF-85s were ever launched or carried by a B-36. 

The XF-85 Goblin on a test flight over Muroc Dry Lake (later Edwards Air Force Base), Calif. On one test flight, the canopy shattered when it hit the trapeze, and the pilot made an emergency landing. On other flights, turbulence prevented the pilot from hooking up to the EB-29B, and he had to land on the lake bed.

Photo credit: U.S. Air Force

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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