I don’t know about you, but I’ve heard “a Formula One car has enough downforce that it can drive upside down on the ceiling” so many times but have never had any proof of this. I, for one, would love to see this put to the test, but I doubt that a Formula One team would risk their hard work by running it upside down just to settle an idle curiosity. I would love to test this myself but not having full, unbridled access to a Formula One team is just the start of problems with this plan. But, here at Claytex, I have access to a Motorsports grade vehicle dynamics simulation suite that is used extensively throughout Formula One.
Almost everywhere I read/hear says it’s possible from an aerodynamics point of view, but there is a lot more to it than just aerodynamics. As you can’t start the F1 car upside down at speed, already on the ceiling, the most feasible way of getting an F1 car on the ceiling is to start on the flat, upright and gain speed normally. Then when sufficient speed has been gained, progressively move up a concave wall along a pipe, maintaining speed, then when holding the inverted driving for a period and then working back down again.
Approaching this from a vehicle and aero-dynamics aspect this manoeuvre provides more difficulty than just running, steady-state, upside down indefinitely. This would require having enough power to raise the car up the wall, while also maintaining enough speed to maintain enough down force; secondly there is the surface of the “pipe” to consider, while I assume there to be enough grip, the articulation of the suspension due to the curvature could cause instability or lifting of one/two of the wheels enough to loose grip/contact. This last point is also coupled with the ability of the tyres to produce enough lateral grip to raise the vehicle in less than optimum conditions.
The VeSyMA – Motorsports library has several vehicle models, including an open wheel vehicle that approximates a Formula One car from several seasons ago in many aspects. The suspension system is similar to that of a formula one car with push rod actuated, double wishbone suspension. It also has similar weight distribution, mass and aerodynamics to that of an F1 car.
While this is not a common road model to create, the road models in VeSyMA, are able to create a surface following a centreline and with banking to match a pipe. The road model generation functions within the Suspensions library to create a road, but with a bit of fettling, a road model was created. This created a single track for the vehicle to contact and the
centreline for the driver to follow that would be representative of the inside of a pipe.
The driver used was the closed loop driver within the Suspensions library. Other than that it was finding a speed and angle at which the vehicle is stable and able to rise up the wall.
On the straight and flat the vehicle has enough down force to create it’s own weight in down force at 80mph, but this would allow zero force from the tyres. Therefore it was a test to see what was the minimum speed at which it would stably complete the manoeuvre. Ramping up in 5mph increments yielded a lot of failures, the main cause being lack of rear grip, upside down oversteer and then loss of down force (now up force) and it falls. This was normally when it reaches the top and attempts to straighten out to stay upside down for a period. Below is an example of that type of failure.
While the requisite speed was higher than expected, it was eventually able to complete the full loop at 125mph:
The wheel loads were a little odd, with the highest increase in vertical (relative to the vehicle) loads being at opposing corners. The front left and rear right initially receiving an increased load of 15%-20% and the other wheels reduced by a similar amount. With the roughly 45/55 front rear weight distribution, when upside down this caused a much larger difference between the front and rear than at the same speed driving along normally.
After a short amount of aerodynamics tuning, where the upside down vertical wheel forces were brought a lot closer together to balance the vehicle, this speed was brought down to 105mph. But this was only able to be done using a large change to the front and rear wing. With each mph lower the ability to control the vehicle lessens, and the smallest error or instability seems fatal to this stunt.
With infinite ability to change the aerodynamics then the speed could be lowered massively but then it would move further away from an F1 car. But with a small amount of tuning to the aerodynamics then a conservative target speed of the car upside down could be as low as 110mph.
So that’s a start; next, full scale testing anyone?
Written by: David Briant – Project Engineer
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