The world’s fastest RC plane reaches a breathtaking speed of 548 mph – without motor

No props, no jets, no rockets – Californian Spencer Lisenby has just broken the world speed record for remote control aircraft, taking an unpowered transonic RC glider to 882 km/h (548 mph) using only the wind. Well, that and an incredible degree of skill in a very dangerous technique called dynamic flight. And even though it’s more or less an extreme hobby at the moment, it has some very interesting plans for the technique and technology behind it.

The wind speeds up like crazy when it comes up a hill, and since the 1960s pilots of “sloping” radio-controlled gliders have used this reliable source of power to keep their aircraft flying pretty much indefinitely – as long as they take care to avoid the wild, all-consuming turbulence of the “shear layer” on the lee side behind the hill where this fast-moving air begins to interact with the much slower-moving air protected behind the ridge.

But over the past 20 years, a group of intrepid RC glider fanatics have experimented and perfected the art of diving through this looping shear layer, using the extreme thrust of high winds to accelerate gliders on the way down, and the rest air below the shear layer as a means of returning mostly uphill without losing energy when flying in a crazy headwind. The plane gains about tailwind speed each time it descends, and loses much less on the way back, picking up energy and speed with each loop.

Not that these amateurs invented the technique; the black-footed albatross has used exactly this flight pattern for millennia, exploiting wind speed differentials created by ocean swells to travel long distances, in any direction, without expending energy.

“I’ve even read that they can perform this maneuver while they sleep,” Lisenby told an audience at TNG Technology Tech Day in 2017, “with their wingtip inches from moving water. We all yearn for the skills of the albatross. But they’re usually trying to get somewhere. We’re aiming for speed.

Dynamic Soaring, or DS, might sound innocent enough as a title, but these extraordinary pilots are now taking unpowered gliders to transonic speeds, dangerously close to the ground. Keep tuning and optimizing this angled loop between high and low speeds, and the glider gets faster and faster, until the pilot mess up the loop, the plane disintegrates dramatically under extreme stress G load or float, or you reach a speed. where drag ultimately limits your ability to go faster.

Lisenby is a dynamic flight enthusiast, an avid pilot and an expert designer of specialized airframes.

DSKinetics

Lisenby isn’t just your average amateur flier. He is absolutely obsessed with the DS, and in addition to holding numerous world records as a pilot, he is also a pioneer in glider design. Indeed, as a prototype designer at DSKinetic, he designs and develops all the huge gliders he flies, in collaboration with a local team, German aerodynamic experts and the University of Stuttgart.

Nothing on the shelf could come close to handling the constant 60-80g loads these things sustain, with spikes reaching 120g as they spin in their incredibly fast oval loops through turbulent air. For context, Formula 1 cars develop up to 6g in the corners, and people tend to pass out at around 8-9g as the acceleration literally drains their brain blood.

The glider that just set the record is a 130-inch (3.3m) DSKinetic Transonic DP, a heavily reinforced, tapered-wing carbon beast with a design honed over many years to fly as fast as possible in dynamic patterns without introducing the odd swept-wing flight dynamics. Theoretically, Lisenby says it should be able to reach 580 mph (933 km/h) in its current form.

On January 19, 2021, Lisenby took advantage of a northeast wind on Parker Mountain, just north of Los Angeles, to reach his highest speed yet, a barely believable 548 mph. To put that into perspective, a 787 Dreamliner cruises around 561 mph (903 km/h).

New RC airplane speed world record at 548 mph

The feat was captured in the video above using a GoPro strapped to Lisenby’s own forehead as he piloted the thing. So you’ll have to forgive the quality of the cinematography – shoot it full-screen on a big screen and you’ll get a feel for how far and how fast it moves, and how crazy the rotational forces are as it moves. she tears a path through the air. Former world record holder Bruce Tebo, who broke the 805 km/h (500 mph) mark himself, was on hand to assist with the launch and operate the radar gun to track the glider’s speed.

Why speed cameras? “We’ve chosen radar as the universal standard around the world,” Lisenby told the TNG conference. “Airspeed has issues – indicated airspeed needs to be corrected for temperature, and it’s difficult for pilots to know the exact temperature and make those corrections. Consumer GPS loses its lock on satellites around 4gs, we went this route. If anyone knows how to get their hands on a military GPS, we should discuss it! compare their speeds to each other, apples to apples, fair comparison.”

Watching Lisenby steal this thing is crazy. Like watching a Formula 1 driver nail perfect laps at lightning speed, it’s hard to imagine a human with such quick reflexes, or a machine capable of withstanding those forces. It thrusts this glider through turbulent air, under full manual control in ever-changing orientations, trying to maintain the optimum oval flight path for massive speed while instantly correcting for tiny roll motions that could plunge the thing into the ground. at transonic speeds. One mistake, and this thing could easily turn a viewer into two well-separated viewer portions in the blink of an eye.

Northeasterly winds blowing up to 65 mph (105 km/h) created a furious airflow over the summit of Parker Mountain, and Lisenby exploited the differential between this high-speed air and the still air on the lee side of the mountain to create a sort of acceleration feedback loop for the glider
Northeasterly winds blowing up to 65 mph (105 km/h) created a furious airflow over the summit of Parker Mountain, and Lisenby exploited the differential between this high-speed air and the still air on the lee side of the mountain to create a sort of acceleration feedback loop for the glider

Spencer Lisenby

“Every time you go out and fly faster than before, you feel like you’re in over your head and your brain can’t stay ahead of what’s going on,” he says. “It’s a very difficult thing to follow. It’s the human factor of dynamic soaring. The faster we go, the faster we have to think. The turbulence makes your paraglider roll, and you have to choose which way to move the glider. stick. to maintain your heading. It takes almost half a second, and in that time the plane has traveled more than 100 meters (328 feet) without even seeing pilot intervention. Sometimes we are only five meters (16.4 feet) from the ground. You see there’s not much room for error at those speeds!”

And yet, it is this thrill that draws him to the sport. When asked if he had thought about automatic roll stabilization, he winces. “A friend of mine called Alan Ciccone in the US has been very active in this. It works wonderfully. The plane flies on its own. You put it in the right path, you pull the elevator so it make the circle the right diameter, and you don’t have to do much on the roll axis. Guess I’m an old school guy, kind of a purist. In fact, I relish the human aspect We could get to a point where I could send my plane up a hill with friends and just log in and find out how fast it went, but where’s the fun in that activity, it has nothing for me. I like the adrenaline and the excitement of feeling the air. You learn by what the plane does for to feel what he encounters up there. It’s really addictive, and I enjoy that aspect.”

It might be a weird kind of extreme adrenaline sport right now, but Lisenby thinks it has a future as a long-range flight mode for autonomous drones with minimal onboard energy storage.

“Let’s go back to the albatross, the original inventor of DS,” he says. “You can imagine a UAV that takes advantage of this flight pattern to cross open expanses of ocean without needing outside power as long as the wind is blowing. If the wind isn’t blowing, well, we could add solar panels at the top of the wing. The plane could land in the water and recharge its batteries, and when the wind picked up, you would use a propeller to take off again and begin your dynamic flight circuit. It could go on forever.

Former world record holder Bruce Tebo launches the DSKinetics Transonic DP glider off Parker Mountain, California, with dynamic climbing expert Spencer Lisenby at the controls.  Tebo recorded a world record top speed of 548 mph measured by radar.
Former world record holder Bruce Tebo launches the DSKinetics Transonic DP glider off Parker Mountain, California, with dynamic climbing expert Spencer Lisenby at the controls. Tebo recorded a world record top speed of 548 mph measured by radar.

Spencer Lisenby

“Another concept,” he continues, “is this idea of ​​DSing the jetstream [narrow bands of strong wind up higher in altitude]. The jetstream has a vertical velocity gradient, you can have winds of 100 mph (161 km/h) at 30,000 feet, but at ground level the wind speed is zero. This speed gradient, while not as steep as the one we use on a ridge for RC gliders…well, it’s not enough to go fast with, but it’s enough to maintain flight. You could possibly jettison a plane from a plane at 30,000 feet, bring it back up, and keep doing it as long as the jetstream stays active. Lehigh University is working on this concept, it’s called the Jetstreamer if you want to delve into it.”

“Where can we go next? I heard it’s very windy on Mars,” he laughs. “Looking at the surface of the planet, I notice that it is filled with these craters. What is a crater but an ideal DS ridge, curled 360 degrees? Regardless of the direction of the wind, you have your DS ready to go!”

What a fascinating and extreme little slice of the RC gliding hobby – which in itself is hardly a massive pursuit. To truly experience the technology, and the enormous passion, intricate knowledge and considerable humor that Lisenby puts into soaring dynamics, I encourage you to watch this full hour presentation from TNG Technology’s Tech Day. As someone who has never seen an RC glider in real life, I found it fascinating. It’s hard not to get carried away by the energy of someone so deep in their niche.

Source: Spencer Lisenby via DroneDJ

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