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‘Crimson Spin’ brings da Vinci helicopter design to life

By on October 12, 2022 0
By Ben Forrest | October 12, 2022

Estimated reading time 6 minutes, 43 seconds.

In the final months of 2020, Austin Prete embarked on a 500+ year-old project.

While working on a master’s degree in aeronautical engineering at the University of Maryland (UMD), Prete began testing, and eventually flying, a small aerial screw-powered quadcopter drone based on Leonardo da Vinci’s design for a helicopter in the late 1480s.

da Vinci helicopter
An engineer has used da Vinci’s aerial screw concept to create a flyable drone that could hold lessons for the future of vertical lift. Austin Prete Image

Da Vinci’s helicopter was designed with compact propeller-shaped rotors and probably never flew in his lifetime due to the limited technology and lack of lightweight materials at his disposal.

And while Prete’s plane – called the Crimson Spin – isn’t likely to be adopted by helicopter or eVTOL developers anytime soon, it provides brain candy for engineers trying to chart the future. of the vertical lift.

Will we ever see an aerial propeller vehicle carrying human passengers?

“It definitely seems possible,” said Prete, who is now an engineer at Aurora Flight Sciences, a Boeing subsidiary. “However, there must be a party interested enough to finance and develop this vehicle.”

da Vinci helicopter
Crimson Spin is based on the University of Maryland’s winning entry to the 2019/20 Vertical Flight Society Student Design Competition, sponsored that year by Leonardo Helicopters. Austin Prete Image

Crimson Spin is based on UMD’s winning entry to the 2019/20 Vertical Flight Society Student Design Competition, sponsored that year by Leonardo Helicopters.

The competition challenged students to design a human-carrying aircraft with propellers that resembled Leonardo da Vinci’s helicopter rotors, which in turn resembled an Archimedean screw.

During the pandemic, Prete – a member of UMD’s 2020 winning team – decided to continue researching the potential of design, albeit on a much smaller scale.

The UMD’s design called for eight-foot diameter rotors to produce enough lift to carry human passengers. Prete’s design used rotors with a diameter of only six inches.

He also added a second blade to each screw – creating a double helix for each – which helped stabilize the original single-surface design during flight.

“The original aerial screw [had] a blade, a surface, therefore [it was] inherently unbalanced,” he said.

Although the UMD team used 3D printing to create their aerial screws, Prete said his were handcrafted with an aluminum shaft, composite spars and hobbyist-grade mylar for the skin surface. .

“At the start of the competition, most of the students on the team also ignored it as impossible until the test, and computational fluid dynamics actually proved it was possible,” Prete said. “Even still, going into my part of this project, I had no concrete belief that it would actually fly.”

At this point, the Crimson Spin can only fly for a few seconds at a time. While hovering is no problem, the air screws don’t provide much forward thrust, so moving sideways is a challenge.

But in a controlled setting, the plane still moves several feet above the ground and can gradually move around a room. Prete noted that aerial screws could be quieter than typical rotors and he sees potential real-world applications for drone-based video shoots.

da Vinci helicopter
Although the University of Maryland team used 3D printing to create their aerial screws, engineer Austin Prete said his were handcrafted with an aluminum shaft, composite spars and mylar. amateur grade for skin surface. Austin Prete Image

“Let’s say you wanted to do an aerial shot, but you didn’t want the rotor blades to make loud noises or large amounts of downwash,” he said. “You could then swap that out for an overhead screw, which would have less down current, less noise.”

Perhaps most interesting from an engineering perspective, Prete said he was able to show that overhead screws produce tip vortices that closely resemble those created by delta-wing aircraft like the Shuttle. spacecraft and the Concorde supersonic jet.

“They’re essentially the same thing, but using a different way of moving air,” he said.

Crimson Spin’s aerial screws achieve most of their lift by creating vortices that flow over the tip of the screws and create a low pressure area on their top surface.

By creating an overpressure zone under the screw, it propels the plane upwards.

“The aerial screw, contrary to popular belief, does not produce [a large amount of] thrust by directing the air downward,” he said. “It is almost entirely the linked-tip vortex of the aerial screw that generates the thrust.”

So, is this a new ultra-fast travel model?

“I don’t necessarily think aerial screws would be good for this application,” Prete said. “Their forward flight speed is going to be detrimental compared to other rotorcraft. But when hovering, the air screws do the same. I’m not entirely sure about the supersonic regions of this one. But that’s something to explore, given experience with delta wing aircraft.

If nothing else, Crimson Spin can serve as a launching pad for further study. It is also further confirmation that da Vinci was a genius well ahead of his time.

“I would be lying if I didn’t say that didn’t come to mind,” Prete said. “Given the absence – at this point – of any human-powered or human-carry capable flight technology, that’s pretty impressive.”