In 1972, the U.S. Navy wanted a supersonic fighter that could launch vertically from small "Sea Control Ships" — pocket carriers without catapults. Rockwell International won the contract with the XFV-12A, a radical design promising Mach 2.4 performance and vertical takeoff from a 200-foot deck. The prototype was rolled out in 1977. It never left the ground.

The XFV-12's genius was its thrust augmentation wing. Instead of swiveling nozzles like the Harrier, Rockwell channeled exhaust from its Pratt & Whitney F401 engine through ducts into the wings and canards. Louvers opened, and the high-velocity jet exhaust would entrain ambient air through ejector slots — theoretically multiplying thrust by 55% for hover, then closing flush for supersonic flight. On paper, this was elegant: one engine, no separate lift fans, full forward-flight performance preserved.

Reality was crueler. When tethered to a gantry at NASA Langley in 1978, the augmentation system delivered only 19% thrust amplification — not the 55% promised. The aircraft, weighing roughly 19,500 pounds empty, could not lift itself. Ducting losses, boundary-layer separation in the ejector slots, and pressure leaks throughout the airframe destroyed the theoretical gains. Engineers spent two years sealing joints and tweaking geometry. Nothing worked. The Navy canceled the program in 1981 after spending around $300 million. The single prototype was scrapped.

Why it failed in 1977:

• CFD didn't exist yet. Ejector aerodynamics were modeled with slide-rule approximations and wind-tunnel scale tests that didn't capture full-scale viscous losses.
• Manufacturing tolerances on the internal ducting were too loose. Every gap bled pressure.
• Composite materials capable of sealing hot ducts while staying light didn't exist — Rockwell used riveted aluminum sheet.
• Flow control was passive. No active blowing, no adaptive louvers — just fixed geometry hoping for the best across all flight regimes.

Why it could work now: The thrust augmentation principle is sound — it's basic fluid entrainment, the same physics powering bladeless Dyson fans. What's changed:

• High-fidelity CFD (Ansys Fluent, OpenFOAM with LES turbulence models) can now predict ejector performance to within 2% — letting engineers optimize slot geometry, duct curvature, and mixing length before bending metal.
• Additive manufacturing in Inconel and ceramic-matrix composites can produce monolithic ducting with zero leak paths and complex internal geometries no riveted assembly could match.
• Active flow control using synthetic jets and plasma actuators can dynamically reattach boundary layers in the ejectors, preserving augmentation across throttle settings.
• Modern engines like the F135 (used in the F-35B) produce 43,000 lbf — vastly more headroom than the 30,000 lbf F401. Even a 25% augmentation factor would yield enormous lift margins.
• Fly-by-wire can stabilize the hover transient that bedeviled 1970s pilots flying analog controls.

The F-35B solved VTOL with a brute-force shaft-driven lift fan that weighs nearly 4,000 pounds and serves no purpose in cruise — pure dead weight above Mach 0.8. The XFV-12's approach, properly executed, eliminates that penalty entirely: the lift system is the wing. For future carrier aviation, autonomous VTOL drones, or distributed maritime aviation, revisiting ejector augmentation could deliver true supersonic VTOL without the F-35B's compromises.