RETRO: Dan’s Magical Bullet… The Gurney Flap قصة Story

It’s been 50 years since a moment of inspiration in a tough test led to an aerodynamic breakthrough that still stands, the Gurney Flap. In a story first published in RACER magazine in 2018, Marshall Pruitt recounts how Dan Gurney’s eponymous invention left Eagle driver Bobby Unser (never easy to do…) and the rest of the 1972 USAC Champ Car field scrambling to repeat the simple, But the device’s forces are incredibly effective at reducing drag and increasing downforce. Half a century later, the Gurney Flap is still one of the performance tools for racing car designers and engineers.

To the birth of Gurney Flap, we owe a debt of gratitude to both excitement and frustration.

If only there were cameras on hand to capture the crazy vibes while playing in Phoenix back in 1972 as development of the new Eagle 7200 Indy from All American Racers got stuck in an unsatisfactory rut around the rugged one-mile oval.

Bobby Anser, the king of Indy cars, was also the steadfast prince to test Dan Gurney’s patience. With the blunt pace continuing to dribble the new open-wheeled AAR contender ahead of the season opener in the desert, the first call in Uncle Bobby’s playbook was to urge Big Eagle for a treat.

Drawing of Ricardo Santos

“We’ve been driving there for three days in Phoenix, and we haven’t had competitive times,” Journey (Pictured, above, tends to speak to Unser at 72) “Bobby Lee comes up and says, ‘Boss, you’re supposed to be able to come up with things all the time — can’t you come up with anything, for crying out loud?’” Dave Despin said in a 2014 interview. “

A post-brawl exchange between the two giants, Gurney thought back to the sports cars he’d raced — Can-Am McLarens and Ford GT40s — that used vertical spoilers attached to the rear bodywork.

Before wings entered motor racing, bolt-on elements, which are used to spoil the trajectory of air as it left the car, were a primitive but effective tool for creating downforce. In the era of the wings, spoilers were largely forgotten outside of NASCAR, where they remain today.

Rear spoiler in sports cars like Dan Gurney’s 1967 Le Mans-winning Ford MkIV car seeded the idea of ​​Dan…Motorsports Pictures

“I wondered if that would work on a wing – wing on the wing, not on the body,” Gurney added. Nearby, Anser’s nerve bundle was waiting to cool off from Dan’s curiosity.

“I said, ‘I lost my speed,'” says Unser, a three-time Indy 500 winner, and so Gurney came up to me. “I can tell he’s upset, but so am I. It’s my test, but I can’t go as fast as I would, and he says, “I’ve got something I’d like to try.” I say: anything you want! How will we do that? When will we do that? what should we do?’ I feel a little upset. He says, “Well, you just keep doing what you’re doing,” and he goes off. “

It was still out of wraps while Gurney mapped out his L-shaped experience in his mind, Unser working himself into suds under the low evening sun.

“My head is going a million miles an hour,” Uncer continues. That “friggin’ thing” isn’t going to run fast, and neither is the engine. It’s just not good stickiness. I run it and get back to it. We all try to think things through, and soon Dan comes up and says, “When’s the time to try my trades?” I say, “Now!” And of course it became more of a test.

“He goes straight to the trailer and has some vice grip and a hammer that goes in there. I don’t know what the hell he’s doing. He quickly comes back with a long piece of aluminum. Nothing else, just a 90 degree aluminum bar, I just look at him and I’m about to lose him.” “.

Wayne Leary, chief mechanic at AAR, must have wondered if boxing gloves were needed…

“We all started arguing very hard, and [Gurney] He says, ‘Here it is. “Put it on the rear wing,” Unser recalls. “I say where?” “Obviously in the back,” he says. I say, “That’s stupid,” and so I said to Wayne, “Pop her rivet, whatever. Just get it on quick. I gotta get this and more done.”

“Wayne and the guys put the friggin thing.” I took this son of a bitch out and did less than one lap, and just discovered the biggest thing ever about racing cars.”

With the Offenhauser’s turbocharged engine making outrageous power, the lines in Phoenix passed in a blur. But during those formative stages of racing car aerodynamics, insufficient downforce from the rear wing profile meant that mediocre cornering speeds were the accepted norm. At Gurney Flap, Unser had the solution that ties the straits and turns together.

With a big secret to be protected, frustration has been replaced by something approaching paranoia.

“I came back and Dan said, ‘Well, what happened? “I say, you won’t believe this. This is the biggest discovery I’ve ever seen of a racing car,” explains Uncle Bobby. He says, ‘Well, why didn’t you do some more laps? I go, ‘Hey, just slow down.’ I didn’t even get out of the car. And I say, ‘Did you get any more that aluminum?’ He says, ‘For what?’ I go, I want a couple up front. [wings] Real fast.

“Then I look around the stands. Where’s the [Unser]? Where are the people of Barnelly? Where are all these people? I don’t even give them a full bosom, see? When he puts them in front, I go out and think, ‘I can’t believe this. It’s a different world. But I won’t do a bosom, because I know even firefighters are enemies…

“Dan is still upset that I don’t run laps, so I tell him, ‘I’m going to break every record out there on the track, and I’ll do it anytime you want. Well, I was really going crazy. I say, you can’t believe what I just found out. You can’t believe what I’ve done. He says, ‘Really?’ I say, you know I’m not lying. You know if I told you I had speed, man, I got it.

“Back in the race, I smoked their ass, won, and broke records. I say, ‘Now the problem isn’t finding the speed; He’s hiding this soldier’s secret. You guys don’t know how big this size is. “

After hitting the field in Phoenix, March 18, Uncer and that L-shaped prodigy would take the top lap of the 1971 Indianapolis Motor Speedway with a full 17 mph en route to pole position in the 56th Indianapolis 500.

In the race, Bobby drove the first 30 laps with ease, but retired with the ignition rotor broken. His teammate, Jerry Grant in the mysterious Purple Eagle race, took the lead on lap 176, but lost any chance to win when he accidentally stopped on the Honor pit to land his last stop on lap 188.

Pole winner Bobby Anser led the early laps of the 1972 Indy 500, but teammate Jerry Grant (above) is closest to winning. Photo by William Mornpeld/Motorsport Pictures

Dan had to wait until 1975 for his first win as an owner (with that guy Unser, of course), but his Eagles would be the cars he would beat through most of the ’70s, and Gurney Flap still played an important role in the aerodynamics of motor racing.

“You know, everyone in the press said, ‘Oh, that was Bobby’s idea,’” Unser says of the simple, but incredibly effective device. “It was my ass. This was Dan’s idea.

But no more arguments [afterward] Between Dan and me. It’s all great because I can run so hard, you just can’t believe it. Flip it, push it, push it, whatever you want, that thing will stay stuck, no one knew why we did it, but that’s Dan. His head used to go like this all the time.”


If air has one major flaw, it’s kind of needy. She hates division, separation, or deviation from the larger group.

Whether it’s going over and under the car or wrapping a wing, a rush to regain its unbroken shape is all the Air wants to achieve. It makes creating the Gurney Flap and its attachment to the trailing edge of the racing car wings one of the finest inventions the sport has known.

Drawing of Ricardo Santos

Air flows at a shallower angle, and will do a good job of staying connected to the top and bottom side of the wing before returning safely after leaving the trailing edge. Start moving some angle in the wing to generate more downforce, and the air attachment at the bottom of the profile will start to suffer. This separation, which creates clouds, is where you lose air efficiency.

With the Gurney Flap installed on the trailing edge of the wing, the air passing under the wing is drawn upward as it reaches the end of its flight. Drag is greatly reduced, downforce is increased, and overall wing efficiency is improved.

In the case of the fateful 1972 All American Racers test in Phoenix, the separation of the airflow beneath the thicker profile of the wing was largely remedied by the introduction of the Gurney Flap as it restored harmony between the upper and lower airstream.

And as racing teams soon learn, Gurney Flaps can be used to increase downforce without resorting to the same sharp wing angles that previously ruined fuel consumption and created major turbulence. Small, lightweight, and hugely efficient, it’s only fitting that the game-changing device bears Dan’s name.

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