23 Jul 2024


$4.5m funding will help to market ‘revolutionary’ motor

Linear Labs believes that its Hunstable Electric Turbine represents a new class of electric motors

A US start-up has raised $4.5m to help market a “revolutionary” electric motor that uses multiple rotors in “ways never before devised” and can adapt to conditions while in motion. Compared to the best permanent magnet motors, Linear Labs claims that its Hunstable Electric Turbine (HET) motor delivers twice the torque density, three times the power density, and twice the output for a given motor size.

The company sees applications for the motor in EVs (electric vehicles), robots, wind turbine generators and variable-speed air-conditioning and pumping systems. The technology could also be applied to linear actuators.

In EVs, Linear Labs says the motor could deliver “unprecedented” levels of torque, removing the need for gearboxes and DC-DC converters, cutting production costs, increasing efficiency throughout the speed range, and boosting ranges by at least 10%.

The company has already filed 50 patents on its “entirely new class of motor”, 21 of which have been issued and 29 of which are pending. The company quotes a US motor expert, Dr Babak Fahimi, director of the Renewable Energy and Vehicular Technology Laboratory at the University of Texas at Dallas, as hailing the HET as “a major accomplishment by an electric motor which supersedes other commercially available electric propulsion units”.

“I strongly believe that the deployment and commercialisation of the HET will result in substantial leaps in terms of energy savings, reliability enhancement, and low-cost manufacturing,” he adds.

Texas-based Linear Labs was founded in 2014 by Brad Hunstable and his father, Fred. Brad is the former CEO and founder of Ustream, a live-video streaming service that IBM bought for $150m in 2016. Fred is an electrical engineer and is chief technology officer of the new company.

The Hunstables invented the HET while designing a device to pump clean water and provide power for small communities in underdeveloped regions of the world. Numerous discoveries “morphed” into the new motor.

“The holy grail in electric motors has always been high torque and no gearbox, and the HET achieves both in a smaller, lighter and more efficient package that is more powerful than traditional motors,” says Fred Hunstable.

A “magnetic torque tunnel” encapsulates the stator in the four-rotor direct-drive motor. All of the magnetic fields are in the direction of motion, “so are not wasted”. The Lorentz and reluctance forces work together – both are created and peak at the same time. Patented field-weakening is achieved by rotating one or both of the motor’s endplates out of alignment.

Linear Labs says that its motor can exceed a continuous power density of 1.9kW/kg (or 2.7kW/kg peak) using standard cooling at a base speed of 3,000 rpm. This “clearly supersedes” other commercially available electric propulsion systems.


The $4.5min seed funding round was led by Science Inc and Kindred Ventures. Linear Labs CEO, Brad Hunstable, says that its backers are showing confidence in “the first major innovation in electric motors in 120 years”.

“Automotive manufacturers are already looking at HET technology as the solution to size, weight and range constraints,” he reports. “With 45% of worldwide electricity consumption passing through an electric motor, the number of industries this technology could impact are endless.”

Peter Pham, co-founder of Science Inc, believes that the new motor has applications “that can impact nearly everything taxing our global needs”. It offers “variable speed and twice the torque while using less voltage,” he adds, “which means it can help electric cars have better range and reduced productions costs, power electric scooters to go up hills and have longer battery lives, and switch air-conditioners to single-stage motors that shut on and off to hold a temperature. We’re excited to see what they accomplish next.”