The McDonnell XF-85 Goblin: The Tiny Fighter That Never Found a Home
During the early days of long-range strategic bombing, the U.S. military faced a critical problem: how to protect heavy bombers deep in enemy territory without relying on distant airbases. The McDonnell XF-85 Goblin, a tiny "parasite fighter" designed to be carried inside a bomber, was one of the most unusual solutions ever attempted.
Conceived as a self-contained defense system for bomber squadrons, the XF-85 was small enough to fit inside a bomber’s fuselage, ready to be deployed and retrieved mid-flight. However, despite its promising concept, the Goblin never reached mass production due to its inherent limitations and the rise of in-flight refueling.
Photo Credit: nationalmuseum.af.mil
Why Was the XF-85 Goblin Built?
By the late 1940s, the U.S. Air Force envisioned a future where massive bombers like the Convair B-36 Peacemaker would fly deep into enemy airspace, far beyond the range of conventional escort fighters.
✔ The Problem: Fighters had limited range, requiring them to turn back before reaching their bomber formations’ most vulnerable points.
✔ The Solution: Instead of relying on external airbases, the bomber itself would carry its own defensive escort fighter.
This idea was not entirely new—earlier experiments with parasite fighters had been conducted using airships and bombers, but none had been successful. The XF-85 Goblin was the first attempt at designing a purpose-built parasite fighter specifically for bomber protection.
The Intended Purpose: A Bomber’s Personal Bodyguard
The Goblin was built for one reason—to defend bombers from enemy fighters in deep penetration missions. Its unique design reflected this mission:
✔ Compact Size – At just 15 feet long, the XF-85 was small enough to fit inside a bomber's bomb bay.
✔ Jet-Powered – Powered by a Westinghouse J34 turbojet, giving it a max speed of 650 mph (1,046 km/h).
✔ Retractable Hook System – Instead of landing like a normal aircraft, the Goblin would reconnect with its bomber mothership using a retrieval trapeze system.
✔ Quick Deployment – The fighter could be launched at a moment’s notice to engage enemy aircraft, then reattach itself mid-air once the threat was neutralized.
Theoretically, the Goblin would be stored safely inside the bomber, only launching when hostile aircraft were detected. This system would allow bombers to defend themselves without relying on external fighter support.
Why Was the XF-85 Never Mass Produced?
Despite its futuristic concept, the XF-85 faced several critical challenges that ultimately led to its cancellation:
The Trapeze Docking System Was Extremely Difficult to Use
- Connecting back to the bomber was nearly impossible in real-world conditions.
- Turbulence from the bomber’s engines made it dangerous and unstable to attempt docking.
- In test flights, the Goblin repeatedly failed to hook back onto the B-29 mothership, resulting in crash landings.
Limited Combat Capability
- Too Small for Serious Firepower – Armed with only four .50 caliber machine guns, the Goblin lacked the firepower to challenge enemy aircraft effectively.
- Short Endurance – With only 30 minutes of fuel, it had very little time to engage enemy fighters before needing to return.
In-Flight Refueling Made It Obsolete
- By the early 1950s, the U.S. Air Force had developed in-flight refueling technology, allowing long-range bombers to travel with conventional fighter escorts.
- This eliminated the need for onboard parasite fighters, making the XF-85 concept redundant.
The Rise of Guided Missiles
- The emergence of long-range air-to-air missiles meant that bombers could be defended from a distance, reducing the need for an onboard fighter.
Due to these challenges, only two XF-85 prototypes were built before the program was officially canceled in 1949.
Photo Credit: nationalmuseum.af.mil
What Are the Takeaways from the XF-85 Goblin?
✔ Innovation Doesn’t Always Mean Practicality – While the idea of a parasite fighter was creative, real-world challenges made it impractical and dangerous to operate.
✔ Technological Advancements Can Render Ideas Obsolete – The rise of in-flight refueling and guided missiles eliminated the need for parasite fighters before they could even be deployed.
✔ Its Legacy Lives on in UAVs – The modern concept of deploying drones from larger aircraft mirrors the XF-85’s original vision, suggesting that the idea of a "mothership" carrying smaller aircraft may still have a future.
Final Thoughts: A Bold But Doomed Experiment
The McDonnell XF-85 Goblin was an ingenious but flawed solution to bomber defense. While it never saw combat, it remains one of the most unique and ambitious aircraft designs in aviation history.
Though the Goblin never got its chance to defend bombers in battle, its legacy continues to inspire modern aerial innovation—a reminder that even failed experiments can shape the future of aviation.
See More:
Wikipedia – McDonnell XF-85 Goblin
National Museum of the USAF – XF-85 Goblin
Plane Historia – The XF-85 Goblin "Parasite" Fighter Built to Protect B-36 Bombers