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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.
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
http://www.electricracenews.com, 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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