Nissan takes a brave leap in Le Mans

[tjts1]

Torque vectoring is a huge factor in making this configuration work.

[Frank Lee]

If it works for an "A" John Deere, it should work for this.

[Rokeby]

So, why spend the big bucks to develop something like this?

Apparently, motor racing is suffering bigtime from a lack of innovation and
being disconnected from current real world realities like fuel efficiency and
sustainability.

The best write up I've found on this car, and IMHO a must-read to
understand what this ecomodders dream car is all about:

The single-seater aero era has held sway since flimsy wings first
scraped the sky in late-60s Formula One. However, the unseen hand
of downforce, allowing drivers to corner with their right foot hard in,
is the enemy of all other efficiencies. Big, thirsty engines towing draggy
barn-door advertising hoardings – 'wings' if you prefer – down straights
have long been red rags to the Greens, and of no long-term interest to
mainstream car manufacturers...

Siamesed front wheels, no wings, a stabilising shark fin… Bowlby's
DeltaWing didn't break with the norm – it nuked it. Yet it would have
been more extreme still had the FIA not deemed a three-wheeler a
motorcycle and thus beyond its jurisdiction...

"When it all started to fall into place, I was completely surprised and
somewhat frightened," he admits. "It's not like I've been thinking about it
for ever; there was an element of 'What have we done?' Not everyone
believes me when I say that form followed function, but DeltaWing is
absolutely not just a styling exercise. It met all its targets – we had a long
fit-for-purpose hit list – and I saw no reason to hide it away just because it's
a little wild..."

"Our goal was to create a car that was twice as efficient for the same speed,"
says Bowlby. "No engine is twice as efficient, so first you must downsize to
reduce the fuel burn. Then you reduce weight. But most of all, you must
reduce aerodynamic drag; we aimed for 60 per cent less. Fair in the wheels,
fit enveloping bodywork, easy. Ah, but that's a sports car, not a single-
seater. Nor would you stand to make the gain we did when we brought the
front wheels into the centre-line and made it, in effect, a three-point plane."

Purnell: "As an aerodynamicist, I know the shape is going to work. It's a little
more challenging in terms of vehicle dynamics. Experts had concerns about
the car's stability in an accident, so the jury is out. When you haven't done
something before, there is risk, and you don't always get it right first time.
Of course, I may just be worrying unnecessarily."

Bowlby: "There were follow-on discoveries. The vehicle dynamics of a 'single'
front wheel with appropriate weight distribution and tyre capacity means it
uses its rubber more efficiently. Throwing away a quarter of a car causes a
cascade of lightness too. You no longer need a chassis with torsional stiffness
because you don't have to redistribute an unbalanced tyre loading around the
car. This allows a huge weight saving, and the majority of what remains –
plus all the roll stiffness – you put across the rear wheels to maximise
acceleration..."

Yeah, yeah, but how will it handle? Understeer springs to the Luddite's mind.

"It's counterintuitive," says Bowlby, "but this isn't an understeer-limited
layout. It has a very rearward weight distribution, so the appropriately small
front tyres won't have to accelerate more mass than their corresponding ratio
to initiate a turn. It will respond to steering inputs incredibly quickly and
completely. And because the roll stiffness is entirely generated between the
rear wheels, the characteristic is responsive turn-in with an oversteering
tendency towards the limit."

Lots, lots more good stuff: Institute Quarterly

Link to the Deltawing site: Technical Features | DeltaWing Racing Cars

[moorecomp]

Originally Posted by theycallmeebryan

I wouldn't drive that at high speeds.

It's backwards, in terms of aerodynamic efficiency and stability.

The guys at Bonneville would like to talk to you about that.

[NeilBlanchard]

From the excellent link Rokeby provided:

KEY SPECIFICATIONS:
Weight with driver 475kg
Horsepower 300 – 330 BHP
Wheel base 2.925m
Aerodynamic drag Cd 0.24
Front track 0.6m
Rear track 1.7m
Front tyre 4.0/23.0 R15
Rear tyre 12.5/24.5 R15
Fuel cell capacity 40 Litres
Brakes Carbon

I notice that the earlier versions of the DeltaWing had the tops of both the front and the rear tires exposed, so I wonder if the Cd has improved at all. The Cd mentioned 0.24 is decent, but far short of the Panhard LM64. So I wonder if the DeltaWing will be even as fast as the Panhard LM64.

[tjts1]

Originally Posted by NeilBlanchard

I notice that the earlier versions of the DeltaWing had the tops of both the front and the rear tires exposed, so I wonder if the Cd has improved at all. The Cd mentioned 0.24 is decent, but far short of the Panhard LM64. So I wonder if the DeltaWing will be even as fast as the Panhard LM64.

Thats because the original design was meant for INDYCAR whch requires open wheel cars.

[aerohead]

Another thread on this car gave 50% drag reduction,which would be Cd 0.55 territory.
At a 60% drag reduction(assuming a constant frontal area) we're looking at around Cd 0.44.Yes?
With less wing the frontal area would be cut,Cd a bit higher,CdA still 60% less.
*less mass
*remarkably less drag
*R-R is impacted favorably
*aero power requirement varies as the cube of velocity
*position pilot for constant polar moment of inertia
*less tire wear
*higher fuel economy
*fewer scheduled pit stops
*position #53 waiver for 'weirdness'
I don't think the competition has a prayer.Delicious!

[NeilBlanchard]

They are claiming a Cd of 0.24.

[aerohead]

Originally Posted by NeilBlanchard

They are claiming a Cd of 0.24.

From looking at an older SAE paper on Indycar aero,if the car is Cd 0.24,then its drag would be about 79.5% lower than a typical racer.
At" 60% less," its Cd would have to be based on an Indycar without any wings or pods,just body and exposed wheels.

[womprat]

Originally Posted by tjts1

Yeah, i dont think you can compare this to a 3 wheeler for many reasons.

Yes the roll center of the single wheel on a trike is necessarily at ground level. With two wheels you can design it in to the the suspension geometry. Not sure what effect that has, comparing the two. Don't know too much about suspension.