Fokker-Republic Alliance: The Dutch-American Supersonic VTOL That Never Was

Has anyone here seen the old American sitcom The Odd Couple? Admittedly, I haven't. But that doesn't mean I can't milk the title to make ham-fisted comparisons between two aerospace companies. Fokker of the Netherlands and Republic Aviation of New York were two radically different aircraft manufacturers across the pond from one another.
Fokker-Republic D.24 Alliance 13 photos
Photo: Fokker-Republic
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That doesn't mean the results weren't stunning the one time their respective engineers worked together. If only the blasted thing could actually fly. This is the story of the Fokker/Republic D.24 Alliance. The VTOL/STOL swing-wing jet fighter that gives a vibe it was built by aerospace engineers after a gnarly psychedelic trip. The kind where your closed-eye hallucinations are three-dimensional. Just one look at this bizarre lump of an airframe in mockup form is enough to strain your eyes.

Does it have a delta wing or a variable sweep swing wing? Is it a fighter, a bomber, or a fighter bomber? Well, the answer to all those things is yes. The D.24 Alliance was designed at the arguable height of the Cold War to provide a type of air defense that didn't require long runways which could be bombed into a crater. The kind of work that the Harrier jump jet and the F-35B would one day become famous for.

In 1961, the NATO Basic Military Requirement 3 (NBR 3) was issued by member nations requesting designs for both a supersonic and a subsonic VTOL/STOL military jet to supplement and one day replace the litany of gen-II jet fighters in service with NATO nations like the Fiat G.91 and the North American F-86. Under this proposal, designs from both European and North American manufacturers were accepted for analysis, thus allowing Republic to take part.

Among the proposals were two German aircraft, the F-104-derived EWR VJ 101 and the bespoke VFW VAK 191B. But also the French Dassault Mirage IIIV, itself derived from the almost inappropriate-sounding Dassault Balzac V. This spirited competition led to a pairing between one Dutch and one American aerospace firm that you'd never have guessed would have had anything to do with each other.

Fokker\-Republic D\.24 Alliance
Photo: Fokker-Republic
On the one hand, you had Fokker based out of Amsterdam in the Netherlands. The once go-to fighter plane maker for the WWI German Military was once again humbled by the Germans in World War II, only to have a resurgence in the civil airliner space after the war. On the other hand, there was Republic Aviation, headquartered in the town of Farmingdale on Long Island, New York.

Had it not been for the Republic P-47 helping secure the liberation of the Netherlands alongside Mustangs and Spitfires, Fokker might never have escaped German clutches.  By 1962, Republic was in a bit of a spot of bother financially, and the two firms had come together to design whatever the heck the D.24 Alliance was. Under the new partnership, a team of Republic personnel led by Alexander Wadkowski, a good friend of the company's lead engineer Alexander Kartveli, flew to Amsterdam to work out the particulars of this new design.

What was needed was a large airframe capable of lifting off vertically via powerful thrust-vectoring engines to intercept Soviet bombers without the need for miles-long runways. In the same way that the A-10 Warthog was built around its 30 mm rotary cannon, the Republic-Fokker D.24 was to be built around its novel and fantastic engine.

The engine in question? It was the Bristol Siddeley BS.100, the same turbofan engine once slated to power the Hawker Siddeley P.1154. Aka, the canceled supersonic-capable follow-up to the original Harrier jump jet. With a close relation to the Rolls-Royce Pegasus engine of Harrier fame, the BS.100 jetted 35,170 lbf (156.4 kN) of thrust in its most powerful configuration.

Fokker\-Republic D\.24 Alliance
Photo: Fokker-Republic
In theory, this racing horse of a jet engine was powerful enough to propel the D.24 to Mach 1.5 (1,141 mph, 1,852.1 kph) at sea level and Mach 2.4 (1,841.5 mph, 2963.5 kph) at its projected service ceiling of 70,000 feet. With help from curved plenum chambers, each of the aircraft's four jet nozzles could pivot on a never-determined range of motion in much the same way the Harrier did.

In the face of charging Soviet fighters and bombers like the MiG-21, MiG-25, and the Tu-22, those kinds of flight stats even the odds even an airbase's runway ceases to exist due to bombing. To add to the goodies, American jets of the day had the king's share of ordnance. Items like infrared AIM-9 Sidewinder and radar-guided AIM-7 Sparrow air-to-air missiles and the lauded M-61 autocannon for up-close encounters with enemy fighters.

As for avionics, it's likely the D.24 would have used something similar to the AN/APQ-120 all-weather fire control radar (FCR) used in the McDonnell-Douglass F-4 Phantom II. Then again, the Thomson-CSF Cyrano II radar from the French Mirage III would have also been a good choice. As if the project needed to be even more internationally complicated, right? We joke.

Either system would have helped this Dutch-American supersonic VTOL interceptor identify and then shoot down Russian bombers with over-the-horizon missile attacks. At some point in the mid-1960s, a full-scale mockup was constructed. One that allowed people to understand the true scale of what Fokker-Republic had in mind for this thing.

Fokker\-Republic D\.24 Alliance
Photo: Fokker-Republic
Sporting a two-seater layout with variable geometry outer wings blended into a delta-shaped inner wing. The D.24 Alliance almost resembled a Saab Drakken if it was given a Super Mario mushroom.Add on a proposed set of swing wing extensions we'd believe if you said inspired the F-14 Tomcat's, and you have the biggest cluster-you-know-what of a design ever conceived in the Cold War.

Had everything gone to plan, the D.24 Alliance could have entered production sometime in the mid-to-late 1960s or the Early 70s if the Fokker-Republic team ran into problems. But it wasn't to be. Why not? Well, it turns out NATO's BMR-3 proposal request, which got the ball rolling in the first place, hit with the force of a wet noodle.

The French and German VTOLs mentioned above that did manage to get built for the program may have wowed spectators at their test demonstrations. But NATO's accountants were ostensibly far less impressed. It was enough to stop research dead in its tracks.

In the end, Republic wouldn't survive much longer past the death of the Alliance. They may have spawned the iconic A-10 alongside Fairchild in their final death twitches, but it wasn't enough to save the company. Meanwhile, Fokker would go on to manufacture the airliners like the Friendship turboprop, the 70/100 jetliners, and even a couple of license-built F-16 Fighting Falcons. But Fokker would join Republic in the afterlife by going bust in 1996 with its assets sold to competitors.

Fokker\-Republic D\.24 Alliance
Photo: Fokker-Republic
In some fantasy alternate reality in a far-off parallel universe, the D.24 flew alongside B-52s, F-4s, and Republic's own F-105 Thundercheif in campaigns over North Vietnam. Perhaps it even got into turning and burning dogfights with North Vietnamese MiG 17s, 19s, and 21s alongside F-4 Phantoms in support of the strategic bombing campaigns of an ultimately impossible attempt to stop the Ho Chi Minh trail in its tracks.

It's doubtful that the D.24 could have turned the tide in Vietnam. But one thing's for sure, the skies over those battlefields nearly six decades ago could have looked far different had the D.24 made it to production. That alone is something to ponder.
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