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How are VTOLs a ‘game changer’ for aircraft industry? Q&A with Formsprag Clutch engineer & sales manager

Formsprag Clutch has decades of experience engineering custom clutch and brake solutions for aircraft manufacturers. In this interview, engineer and sales manager Chris Cronin explains how VTOLs/eVTOLS will shape the future of the aircraft industry.

A global leader in clutch and brake technologies, Formsprag Clutch is the premier partner for aircraft engineers working on VTOL and eVTOL designs.

Just ask Chris Cronin.

A graduate of the University of Detroit, Chris has worked in engineering and sales at Warren, MI-based Formsprag Clutch for over three decades.

His primary focus has been in overrunning and sprag retainer clutches for aircraft, but he’s also dabbled in engineering electric clutch/brake solutions. A veteran of the aerospace and defense industry, Chris is excited about the future of the industry. And he believes that future is going to be shaped by vertical flight.

In this Q&A, Chris explains what “VTOL” and “eVTOL” vehicles are, and how Regal Rexnord Powertrain Solutions can help lift these aircraft into reality.

This interview has been condensed for clarity and accuracy.

OK, first question. What is a VTOL?

‘VTOL’ stands for “vertical takeoff and landing vehicle,” which has recently morphed into large vehicles able to carry cargo and people. These vehicles are sometimes fully electric, in that case you see them referred to as ‘eVTOLs.’ But the larger they are, the more likely they are to have a hybrid drivetrain.

Why are VTOLs such a big deal?

We're seeing a major transition in how air flight is going to work in the future. It’s typically been a fixed wing aircraft with big engines on it, propellers or jets … it moves forward, and carries a lot of people or cargo. Helicopters have always been a very niche market; they tend to be search-and-rescue, military, medivac type aircraft. For people that have enough money, they can be personal vehicles.

Where we're seeing with these VTOLs ... it's a game changer in the aerospace industry. They’re moving incredibly fast. Typical airframe development can be 10 to 20 years for a helicopter or a new plane. These guys are talking three to five years.

What does a Formsprag overrunning clutch do in an aircraft application?

Simply put, overrunning clutches allow the helicopter to auto rotate in the event of a powertrain failure.

If you think of a helicopter ... if you lose power, you can do what they call an “auto rotation” … you can get the vehicle down to the ground safely, so people can get out. In that case, you're less worried about the airframe, you're worried about the people.

When you think about a drone, to get these four corners working … if you lose power on one of those four corners, the aircraft's going down and it’s not in control. There's no nice way to land it.

What we're seeing, especially on the electric drives and hybrid drives, is the need to have redundant propellor motors. In the event of a motor failure, a freewheeling clutch disconnects the failed motor so the rest of the propellor motors can keep on driving.

For example: say I have a dead motor, I am essentially mechanically disconnected from the drive train. The other motor picks it up, keeps on running, and now the airframe’s able to go on to a safe landing zone. It's a “land now” type situation, but you've got control to get down on the ground.

What about the electric clutches and brakes? How do those function in aircraft like VTOL?

On the electric clutch/brake side, where we're seeing the applications right now is for either stowing or positioning the vertical lift propellers.

If I fly an eVTOL or VTOL horizontally, I can aerodynamically park these lift rotors, so they are parallel to the fuselage of the aircraft. And the brake parks it and holds it there.

So those are the two big applications that we're seeing for the clutch/brake solutions.

What is Formsprag's role in the drivetrains for VTOL/eVTOL aircraft?

For VTOL drivetrains, we provide a freewheeling clutch that can disconnect a dead motor from the drive train, in the event of engine failure. We can also provide electric clutch brakes for stowing or positioning the vertical lift propellers.

This is nothing new … our overrunning sprag clutches and electric clutches and brakes are already on many aircraft.

ECB and Overrunning Sprag Clutch

Electromagnetic Clutches and Brakes (left) and Overrunning Sprag Clutches (right). Learn more.

For VTOL designs specifically, you could find use for our solutions on vehicles that are electric battery, electric hybrid, electric hydrogen, or turbine engine powered. Our products work with multirotor, tilt-rotor, or decoupled propulsive drive systems … piloted or not piloted … on aircraft that carry passengers, cargo, or both … incorporate pusher or lateral rotors or fans ... Really, whatever your specific VTOL looks like, we can find a way to custom engineer our solutions to fit your designs.

When you’re working with engineers at VTOL/eVTOL startups, what are the most common questions you’re asked? What types of engineers are you working with, and what kinds of design questions do they have?

These startups typically have a mix of mechanical and electrical engineering backgrounds.

The most common questions we’re asked, at the design level, are actually related to our experience level in the aerospace market. Our understanding of these applications, our knowledge of regulations and quality requirements. The certifications that we have, and why those certifications matter.

Our facility in Warren, Michigan has key AS9100D & ISO9001:2015 certifications. Not only are our solutions pre-certified with the regulatory boards, we have staff here who can help explain these government regulations and requirements to engineers and product managers who may be navigating this space for the first time in their careers. Our customers find that knowledge and expertise extremely valuable.

Beyond that, I always like to tell people about our longevity in this field. Formsprag Clutch has been serving the aerospace industry since 1943. “Clutch” is in our name. Since then, we’ve become a household name for aircraft OEMs who value our creativity, passion, and engineer-to-engineer collaboration. We hope to continue those relationships with engineers in the VTOL sector.

To speak with Chris or another member of the Formsprag Clutch VTOL/eVTOL team, and for more information on our powertrain solutions for these vehicles, click here.

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