The returning fan car revolution that could suit F1

Earlier this year, the Goodwood Festival of Speed course record finally fell, to the McMurtry Speirling. Nick Heidfeld had used McLaren's 1998 Formula 1 contender, the MP4/13, to set the bar at 41.6 seconds in 1999 but Max Chilton managed to blitz this by taking his remarkable electric-powered machine up the hill in 39.08s. The Volkswagen I.D. R's sub-40 second run in 2019, also eclipsed by Chilton, was not officially recognised as a record due to it taking place on the Saturday.

There are a number of aspects that make the Speirling unusual but the most dramatic – and most obvious from outside the car – is the twin-fan set-up that lowers the pressure under the vehicle to improve grip. In the case of Goodwood, the drama of outright speed was emphasised by an unusually dusty surface resulting in a visible rooster tail trailing the car as it stormed up the hill.

This is not the first time fans have been fitted to cars to create downforce, although it’s uncommon because previous examples have invariably been quickly opposed and removed from the race series they were built for.

The idea of mounting a wing on a car to push it down onto the road at speed and increase grip is thought to have originated with Michel May when he mounted one on struts above the cockpit of his cousin's Porsche 550 in 1956. Although wings give an overall advantage they are inefficient as they create less downforce at lower speeds (usually on corners where they are needed) and bring notable drag at high speeds.

Jim Hall added large wings to his Chaparral 2E Can-Am car of 1966 and 2F sports-prototype in 1967, and reduced the disadvantages by changing the angle of the wing to minimise drag when on the straight. The FIA soon banned moving wings and this pushed Hall on to what remains his most radical idea in 1970.

The Chaparral 2J was built to contest the no-holds-barred Can-Am series and neatly sidestepped the problems that come with fixed wings by having two fans mounted on the rear face of its boxy bodywork to lower the pressure under the car.

Chaparral introduced the fan car concept to motorsport with the 2J Can-Am racer in 1970

Photo by: Motorsport Images

The initial idea allegedly came from a 12-year-old enthusiast who suggested that a helicopter rotor mounted to the bodywork could “suck the air out” and therefore “suck the car down”. Hall and collaborator Hap Sharp turned the boy's concept into a working solution by using a two-stroke snowmobile engine to drive a pair of repurposed cooling fans from a tank.

This arrangement meant the fans could always be spinning at their peak 6000rpm, giving a constant downforce of over 2000lb. Crucially, Hall and Sharp also used side skirts that moved vertically to match any change in the rideheight of the car, stopping ambient air passing into the low-pressure area underneath. Despite being dogged by unreliability, the 2J showed immense promise, according to some reports being able to corner with a force of 2G.

Faced with such a gain in performance, it didn't take long for the opposition to raise their objections. As ‘moveable aerodynamic devices’ were banned, the accusation was made that the spinning fans failed to the meet the regulations. There were also complaints that debris was drawn up from the track then thrown backwards at following drivers. A year later the Chaparral fan car itself was banned and retired to a museum.

"I've never seen such consternation in the paddock. Ken Tyrrell was frothing at the mouth and [McLaren’s] Teddy Meyer was flicking at his Rolex watch strap so much I thought it would break" John Watson

The next time such a device would be seen in a race was 1978, when Gordon Murray penned the iconic Brabham BT46B. Surprisingly, the inspiration for this car, intended to counter the ground-effects advantage of the Lotus 79, wasn't the Chaparral but rather an experimental cooling system tested by Tyrrell.

Originally developed in late 1977, the Tyrrell 008 had low-mounted horizontal radiators and a large fan driven by the engine crankshaft ‘pulling’ the air through them. Unfortunately, the cooling was marginal so conventional radiators had to be used throughout its race career. However, an amount of downforce was created as a by-product and David Cox, who had been at the test, was aware of this.

The Brabham BT46, also under development at the same time, had been designed to use heat exchangers rather than radiators in a bid to reduce mass. Cox contacted the team and correctly predicted this would be unsuccessful, then joined Murray at Brabham bringing the information from the Tyrrell test with him.

Brabham had another problem at the time in that the flat-12 Alfa Romeo engines it was using left no room for ground-effects venturi tunnels, so Murray and his team had to be more inventive when it came to levelling up the playing field. This all led to a large fan being mounted at the rear of the BT46, this time driven via the gearbox, to create the BT46B ‘fan car’.

The Brabham BT46B only contested one F1 race as team owner Bernie Ecclestone had his eyes on a bigger prize

Photo by: David Phipps

John Watson, one of only two drivers to race it (Niki Lauda being the other), recalls those times with an animated passion that hasn't diminished despite the 44 years that have passed since. He sees the BT46B as having advantages over both the Chaparral, as it didn't have to carry a separate motor to drive the fan, and the ground-effects cars as “the maximum downforce was available in the corner, where it’s needed”.

Crucially, a minimum of 50% of the fan's work was drawing air through the radiators mounted above the engine, ensuring the argument could be made that its primary purpose was cooling, not aerodynamic. A solution that met the letter of the law but, Watson concedes, arguably not the spirit.

However, there was still so much downforce being generated that he clearly remembers being told not to “rev the engine or blip the throttle in the paddock as the car would be visibly pushed down onto the road”. The presence of skirts sealing the rear bodywork to the ground leave no doubt that, despite any technical arguments, creating downforce was a key aspect of the design.

Back in early 1978 Watson had no idea of what was coming until he became the first driver to take the BT46B on track at a secret test session at Brands Hatch. Although today he still feels aggrieved at having carried out the “development donkey work”, with notional team equal Lauda reaping the benefits in later testing, it’s clear the response to the car's unveiling at the Swedish Grand Prix provides some compensation.

“I've never seen such consternation in the paddock,” Watson relates, continuing with palpable delight. “Ken Tyrrell was frothing at the mouth and [McLaren’s] Teddy Meyer was flicking at his Rolex watch strap so much I thought it would break.” His greatest pleasure still comes from the fact that “Colin Chapman and Mario Andretti were particularly pissed off”.

A new driving technique had to be adopted to maximise the advantage. “I was generally early on the brake, then on the throttle in mid-corner,” recalls Watson. “By the apex and exit the downforce meant I gained overall despite the low entry speed.”

Although Watson retired from the race, Lauda won but team principal Bernie Ecclestone had an eye on the long game and agreed to withdraw the controversial car from further races. The BT46B was sacrificed after a single outing on the altar of paddock unity during those critical early days of the Formula One Constructors’ Association.

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Watson feels Brabham's BT46B was worth it for the friction it provoked in the F1 paddock

Photo by: Motorsport Images

As with the Chaparral before, the official reasons given were that the fan constituted a moveable aerodynamic device, along with concerns about debris being blown out the back of the car. Andretti was one of the most vocal to complain about problems following it, however Watson maintains not only that the BT46B was legal but also that this was a minor issue. He remains fiercely proud of what the team achieved with the fan car and it's little wonder that his pole position in the conventional BT46 at the following race in France remains his emphatically stated moment of “greatest satisfaction and fulfilment”.

Rather than contesting a race series, the McMurtry Speirling was designed purely with the intent of generating headline grabbing times around circuits to demonstrate a viable alternative to increasingly larger and heavier electric vehicles (EVs). As such the project does not have to conform to existing race series rules and the engineers were free to explore ideas denied to mainstream motorsport.

What they have produced is the smallest, most aerodynamically efficient single-seat car they can to fulfil the basic brief. Crucially, the core focus on removing mass from the car as a whole means that smaller and lighter batteries can be used that, in turn, bring even further benefits.

The ability to transmit power through looms to motors that run the fans directly has allowed the system to be integrated much more completely into the car as a whole. There is even redundancy for the first time

This has resulted in the Speirling being a mere 3.5 metres long and 1.7 metres wide, matching the footprint of a 1960s F1 car. The drive to minimise size and drag rules out aggressive or outsized passive aerodynamic devices and it is this, at least in part, that has led to the adoption of fans to generate downforce.

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Uniquely among the fan cars though, the McMurtry has additional advantages that come with the modern battery-powered EV. The overall packaging and requirements for electric propulsion open up possibilities for installation that are impossible with internal combustion engines. The ability to transmit power through looms to motors that run the fans directly has allowed the system to be integrated much more completely into the car as a whole. There is even redundancy for the first time, with each fan specified for a greater capacity than required so downforce can be maintained in the event of one failing.

It may be that, finally, modern technology has allowed the architecture of the fan car to be optimised.

It would, though, be wrong to look on the Speirling as having been designed purely to set a hillclimb record with little regard for any other considerations. Despite its small size, the all-composite structure is designed to modern motorsport standards, while the small frontal area and attention to drag seeks to make the most of the 60kWh battery developed by McMurtry, with cells from Molicel. A duration of 30 minutes is claimed for circulating a track at GT3 speeds or alternatively a WLTP (Worldwide Harmonised Light Vehicles Test Procedure) range of over 300 miles on the road.

Efficiency is a key objective with the McMurtry - could its adoption of fan power be more widely used?

Photo by: JEP / Motorsport Images

Beyond the attainment of cold performance figures, building a light and agile car was also seen as being fundamental in maximising driving pleasure. Ex-F1 pilot Chilton describes the driving experience as “the same as a top-tier conventional racing car in the way that you can feel understeer if you brake too late and try turning in or that you turn in aggressively at high speed and you feel the rear rotating. Where the car is unique is the downforce is always the same.” As with the Brabham, the fundamental difference in technique comes about when braking for a corner.

“We are used to stomping on a brake pedal on the first application when an aero car has maximum downforce and then instantly reducing your pressure as the air speed over the car reduces your grip level,” adds Chilton. “With the Speirling the downforce grip doesn’t reduce as we slow down.”

There are plans to build a limited-edition road going version of the Speirling so you can experience this for yourself. But, given F1's modern-era problems, it's difficult not to wonder - is it time for the top tier of motorsport to finally embrace this technology?

A lack of dependence on passive aerodynamics would remove the problems of loss in downforce caused by running in the wake of another car. The porpoising issue that has dogged the 2022 season so far is also eliminated. There would be the additional advantage that potentially smaller cars would open up overtaking opportunities on tighter circuits such as Monaco.

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Against this, the ultimate ability to generate very high cornering forces may have to be limited on the grounds of safety and, despite filters resulting in only fine dust being blown out the back (with that directed down onto the road by the exhaust), debris still has to be considered. At least testing could categorically reveal once and for all whether this really is an issue or not.

From this, the changes required to the rules wouldn't be simply a line or two but would result in a complete revision. This would be a huge task, perhaps reason alone not to consider it.

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Alternatively, as Watson would undoubtedly love to see, F1 could reset itself by having an absolute minimum of rules to allow maximum creativity. This would give the teams the freedom to develop their own ideas about how to go quickest and still cross the line at the end, ideas that may well include forced extraction of air from under the car.

Thanks to McMurtry though, no matter where this may or may not eventually lead, the fan car has once more returned. And this time it looks like it's here to stay.

Chilton's new Goodwood record in the McMurtry Automotive Speirling could usher in a greater use of fan technology going forwards

Photo by: JEP / Motorsport Images