This U.S. Air Force Jet was Built to Defend Nuclear Bombers

This U.S. Air Force Jet was Built to Defend Nuclear Bombers

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By Sebastien Roblin, The National Interest

Its manufacturer called it the “Goblin”—and by looks alone, the egg-shaped jet certainly deserved the name. The McDonnell XF-85 jet resembled little more than a pressurized cockpit on top of a bulbous J34 turbojet engine, with small stubby swept-back wings that could fold inwards. Rounding out its ghastly appearance were an unusual three tail stabilizers, three shark-like belly-mounted fins, and a giant extendable hook rising from the open snout of its jet intake.

To top off the Goblin’s disreputable looks, it lacked landing gear, and had to make do with a retractable steel skid for emergencies. That’s because the XF-85 was a “parasite fighter.” It was designed to be carried aloft by a huge nuclear bomber and air dropped to defend its ponderous mothership from attacking enemy fighters. Upon accomplishing its mission, the Goblin was supposed to use its protruding hook to snag a ride back to home base attached to its mothership.

The XF-85 was intended to protect gigantic B-35 fly-wing and B-36 Peacemaker strategic bombers designed to fly thousands of miles carrying nuclear weapons in their capacious bomb bays. These had fuselages large enough to fully enclose a Goblin in their bomb bays.

Though it may sound like a concept strait out of a Rescue Rangers cartoon, parasite fighters actually had a long but obscure history. The first were British biplanes that were tested hooking up to military airships during World War I. Then during the 1930s the Navy deployed F9C Sparrowhawk biplanes on board 239-meter-long helium-filled rigid airships Akron and Macon. The Sparrohawks also used hooks to “land” onto a trapeze extended from the airships. However, both scouting airships had crashed by 1935.

During World War II, the Soviet Union briefly mounted I-16 fighters onto a hulking TB-3 bombers for air strikes in 1941, and Japan deployed rocket-powered Okha (“Cherry Blossom”) kamikaze plans on G4M bombers.

The Air Force’s formally requested its own parasite fighters in January 1944 at time its long-range strategic bombers were experiencing heavy losses to German fighters in World War II. In the short term, the Air Force would develop effective long-range piston engine P-47 and P-51 fighters with drop-tanks to accompany the bombers all the way to target.

But the Air Force knew new jet fighters would soon enter service that would dramatically outperform piston-engine fighters—while also guzzling fuel at a much faster rate. Thus, the theory went that having a bomber lift parasite jet fighter into enemy airspace would overcome the range problem.

However, only the St. Louis-based McDonnell aircraft company responded to the Air Force’s request for proposals in March 1945. That October the Air Force ordered two XP-85 prototypes (later re-designated XF-85s) and additionally planned for parasite-carrying capability in its forthcoming B-36 bombers, some of which were planned to trade away their bombloads entirely to carry three XF-85s.

The Goblin actually exhibited decent handling characteristics and theoretically could attain respectable speeds of 650 miles per hour on its lone axial-flow turbojet. Four .50-caliber machine guns in the side fuselage were to constitute its relatively light armament.

As the B-35 never entered service and the B-36 was still being developed, in 1948 the Goblin was instead “nested” in the yellow-painted belly of a specially converted EB-29B bomber named “Monstro.” The little jet was attached via a retractable trapeze based on the type used on the Akron-class airships, with the lower half of the Goblin protruding from it.

 As Goblin #46-523 was damaged in a crane accident during wind tunnel testing, #46-524 would fly all but one of the trial flights.

At first the XF-85 was carried aloft and retracted into launch position but not deployed. Finally on August 23, McDonnell test pilot Edwin Schoch launched the XF-85 from the extendible trapeze it was mounted on. The Pennsylvanian was an experienced Navy Helldiver pilot decorated for damaging a Japanese battleship during the Battle of Leyte Gulf.

However, turbulence from Monstro’s air-cushion buffeted Schoch as he attempted to gently guide the Goblin back onto the hook for recovery. The two-ton fighter weighed less than half the weight of the F-80 jet he had practiced hook-up approaches with earlier.

After ten minutes of unsuccessful hook-up attempts, to the horror of the B-29 crew the XF-85’s canopy smashed into the hook, shattering the glass and ripping off Schoch’s flight helmet and oxygen mask.

The Goblin tumbled downwards, but Schoch managed to regain control of the Goblin and skid-land it on a dry lake bed in the Muroc desert below in southern California.

Undeterred, Schoch recommenced testing on October 14–15 with a repaired Goblin modified with upward-folded wingtips for more precise control.

On three occasions, he successfully managed to hook bizarre jet back on to the EB-29 mothership. But two subsequent hookups failed, with the skyhook actually breaking on the last attempt. Schoch was forced to crash-land his XF-85 each time. XF-85 46-523 also failed to hook up on its only flight in April 8 the following year.

Though McDonnell sought to devise an improved trapeze system, news of the XF-85’s difficulties, combined with constrained budget, led the Air Force to promptly cancel the project in October 1949, leaving Schoch the only pilot to have ever flown the Goblin on its seven flights.

The Pentagon’s faltering interest stemmed from several new development. Excellent Soviet MiG-15 jetsalready promised to outperform the XF-85. The Air Force had already ordered a new long-range escort fighter drawing upon wingtip fuel pods resulting in the XF-88 and XF-90 prototypes. And improving aerial-refueling technology promised to soon extend the combat radius of its short-range fighters.

The Air Force wasn’t entirely done with parasite fighters, however. The service’s Fighter Conveyor program (FICON) focusd on pairing F-84 Thunderjet fighter-bombers with the B-36.

Project Tip Tow involved having two modified EF-84Ds towed by the wingtips of an EB-29, but turbulence and wing-strain complicated the project. A fatal F-84 on B-29 crash ended the program.

Project Tom-Tom alternately sought to implement the wingtip approach using a specially modified GRB-36 Peacemaker and two RF-84F Thunderflash swept-wing reconnaissance jets, was also terminated after a nearly fatal decoupling.

The Air Force instead returned to the Goblin-like concept of belly-mounting jets from retractable trapeze hooks. They successfully tested mating F-84s to a GRB-36, though the Thunderjets couldn’t fit all the way inside the Peacemaker.

The scheme worked well enough that ten GRB-36s and twenty-five RF-84K Thunderflash armed reconaissance fighters were operationally deployed from 1955–1956 before being replaced by U-2 spy planes.

As for the Goblins, the parasite jets went on to enjoy a quiet retirement and can be seen at the U.S. Air Force Museum in Dayton, Ohio and the Strategic Air Command & Aerospace Museum in Ashland, Nebraska.

Sébastien Roblin holds a master’s degree in conflict resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.

Image: Wikimedia Commons.

This piece was originally published by The National Interest

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