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The world-first demo on 10 April was made possible by a proprietary fan system on the McMurtry Spéirling hypercar, capable of generating 2,000kg of downforce – without any forward movement.
The eye-catching display was the latest impressive achievement enabled by the Downforce-on-Demand system. The Spéirling prototype is the fastest around the Top Gear track, beating an F1 car by 3.1 seconds (although both were disqualified for not meeting requirements), and it also holds the record for the fastest hill climbs at Goodwood Festival of Speed and the Laguna Seca Corkscrew.
Now McMurtry is planning to build 100 at its Cotswolds factory – and the tech could have wider applications.
Beyond convention
“To enter the automotive world as a new brand, we concluded in about 2018 that we needed to produce a small vehicle that had track performance beyond any sort of conventional measure,” says company director Yates, who founded the firm with the late Sir David McMurtry in 2016. But how to make a small vehicle with F1-like performance?
“I’ll just suck it to the ground” was the response from prolific inventor McMurtry. The active downforce technique was explored in the Chaparral 2J and the Brabham BT46 F1 car in the 1970s, but subsequently mothballed.
The system on the all-electric Spéirling works by creating a partial vacuum in a sealed area under the car. The force of that low pressure region acting on the bottom of the chassis surpasses the mass of the vehicle, providing huge amounts of grip in normal use – and suspending it above the ground when inverted.
Despite successful tests in the run-up to the jaw-dropping stunt, Yates says he got “very nervous” as they approached “the opportunity to destroy a hugely valuable and important prototype”. While calculations showed it was possible, determining the force required to maintain friction at 90º was one of the tricky elements. “If you mess it up and you smash up millions of pounds’ worth of invaluable prototype… then all of a sudden it looks like you’ve done a very silly thing,” he says.
Sitting in the car on the specially built rotating rig was an incredibly strange feeling, he adds. “The funny thing is the simple things – like when you flip the rig, suddenly it’s quite dark underneath it; you’re in bright daylight and then suddenly you’re in the shadow.”
On and off track
The upside-down drive is a compelling image, but what it reveals is fairly simple – absurd grip levels, even at low speeds. This was such an important target for the project because race cars spend most time on a given lap in its slower sections, Yates says. “If you can take something that was previously, let’s say, a 60mph corner and you can make it a 100mph corner, you have a very significant improvement in lap time,” he says.
The consistent grip has another unusual effect – drivers reportedly become accustomed to the performance of the car much quicker than in vehicles with conventional linear grip.
Yates sees opportunities to improve vehicles beyond racing applications, and the company is in discussions to sell the technology to other companies. He is even open to more dramatic demonstrations in future: “If, let’s say, we got a phone call from Monaco and they wanted the tunnel to be driven upside down, we’d be interested in that.”
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