Thoughts on Dallara's Formula E design sketches

Dallara has released preliminary sketches of their Formula E chassis.

These are 'Sketches' rather that engineering drawings but they should give some indication of design direction.

Top view
Side view

The drawings shows signs that there is some credence being given to the notion that reducing drag might be of greater importance than creating down force. Induced aero drag requires more power to go a set distance. The more power needed, the more batteries required. Batteries are heavy. Heavy race cars are rarely a good idea.

The wings are single plane, not the multi plane we are used to seeing in F1: Higher efficiency, less down force. Some reasons to keep wings at all are: Technically, they give a quick adjustment tool for aero balance; Commercially, they offer nice flat space for advertisers. The front wing is very skinny and its main purpose might be to support the front tire fairing.

The fat exposed tires create a lot of drag, so fairings have been added in front of both the front, and the rear tires. There are greater gains to be had by cleaning up the air behind the tires but I suspect an effective fairing on the rear of the front tire would impinge on the front of the rear body work. A rear fairing for the rear tire would extend a long distance behind the car and possible make the car too long.

I am less sure of the purpose of the two small wings coming directly out from the side of the cockpit. They might be there to offer some crash absorption in the event of a side impact since there are no side pods protecting the driver.

The air intakes are significantly smaller than the ICE standard. This works since internal combustion engines waste around 70% of their energy as heat while electric motors waste around 10%. The smaller air intakes are another good step in drag reduction.

I would guess normal radiators and liquid cooling. Perhaps separate systems for the motors and the batteries since they can have very different heat ranges. The air intakes size will change as Dallara and McLaren start testing their bits together.

The batteries are in the rear of the car. It also looks like traditional rear wheel drive since there does not seem to be anything indicating electronic all wheel drive.

If motors were being mounted in the front, they would be mounted as low as possible. Then the nose floor would be flat rather than the raised version that is shown. Of course, wheel mounted motors are possible but I would guess designers would choose the aero drag of exposed half shafts and centrally mounted motors over having the motors as un-sprung mass.

If the drawings showed the front suspension, we would look for power and cooling lines (wheel motors), half shafts (centrally mounted all wheel drive), or nothing extra (rear wheel drive).
Press releases have stated that McLaren is working on a single motor system with a multi gear transmission. I wonder if that will change as they recognize the importance of the efficiency losses of a transmission and the different torque curve an electric motor can provide. The Tesla Roadster is a good example of performance engineers abandoning their multi gear transmission in favor of a single gear.

If they decide to switch to separate motors driving each rear wheel (software differential), it would be hard to pick up from a drawing.

As David Herron posted on, the Spark SRT-01E "Looks like a race car". I agree. It looks like a conventional gasoline powered formula car with a few drag-reduction aero tweaks. I think by starting from such a standard high drag model, it will be difficult to create a vehicle that can go very far at racing speeds. Then what does the driver do; abandon his racecar and hop into another chassis? Wait... What? Seriously???


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