It looks like a Soviet defector’s nightmare. Four giant ducted fans, each two metres in diameter, mounted on the corners of a stubby fuselage, tilting independently between horizontal and vertical flight. The whole machine hangs from those four fans like a hovercraft in the wrong dimension. And in 1967 — twenty years before Osprey first hovered — it was the most promising VTOL design on either side of the Atlantic.

The Bell X-22 was the United States Navy’s serious attempt to skip the helicopter generation entirely. Two prototypes were built. Three hundred and seventy flight hours were accumulated. And the lessons learned in those flights are still being applied — by Bell itself — to the V-280 Valor and now to the MV-75 Osprey replacement that Special Operations Command confirmed last week. The X-22 may be the most consequential aircraft most people have never heard of.

A different solution to the same problem

The 1960s were the decade everyone tried to solve VTOL. The British tried with the Hawker Harrier’s vectored-thrust nozzle, which worked. The Germans tried with the Dornier Do 31 jet-VTOL transport, which did not. The Soviets tried with the Yakovlev Yak-38, which mostly killed its pilots. And the Americans tried no fewer than five separate paths simultaneously — Hiller X-18 tilt-wing, Curtiss-Wright X-19 tilt-prop, Ling-Temco-Vought XC-142 tilt-wing transport, Bell XV-3 tilt-rotor, and the X-22.

The X-22 was Bell’s attempt to combine the best parts of all of them. Like the tilt-rotor, it kept the rotors at the wingtips. Like the tilt-wing, it tilted big lifting surfaces from vertical to horizontal flight. But unlike either, it put the fans inside ducts — circular fairings that increased static thrust by roughly 30 percent compared to an open propeller of the same diameter, and that protected the blade tips from foreign-object damage on rough field operations.

Why ducted fans matter

A ducted fan is, mechanically, a fan running inside a closely fitted shroud. The shroud captures and redirects the air that would otherwise spill around the blade tips. The result is more thrust, less noise, more safety on the ground, and — crucially — better hovering efficiency at lower speeds. Modern eVTOLs from Joby, Lilium, Eve and Archer have all settled on variations of the ducted-fan concept. The X-22 got there first by 60 years.

Why it never flew operationally

The X-22 worked. The second prototype made the transition from hover to wing-borne flight cleanly on multiple flights. It hit 410 km/h in level flight. It carried a six-troop payload in hover. By every technical measure, the programme was a success.

Three things killed it. First, the helicopter. By 1968 the UH-1 Iroquois was in mass production at one-fifth the cost per airframe, and proving in Vietnam that you could move troops at speed without solving the VTOL transition problem. Second, the political pressure on defence budgets that came with Vietnam. And third, Bell’s own tilt-rotor work on the XV-3 was producing data that suggested an aircraft with proprotors on the wingtips, not ducted fans, would scale better to large troop transports. The XV-15 followed the XV-3. The V-22 Osprey followed the XV-15. The V-280 Valor followed the V-22. The MV-75 — the Osprey replacement Bell now has on US Army contract — follows the V-280.

The X-22 never made it to production. It also never crashed. Both prototypes survive — one at the National Museum of the US Air Force in Dayton, Ohio, the other at Niagara Aerospace Museum in Buffalo, where it was built. They are, in 2026, the most underappreciated VTOL aircraft on display anywhere. Walk up to one and you can see the genealogy of every modern tiltrotor, every eVTOL air taxi, every ducted-fan drone — running back to four engines, four ducts, and a Bell test pilot in upstate New York in 1967.

Sources: NASA Ames Research Center, Niagara Aerospace Museum, National Museum of the US Air Force.