RE: Nissan powers DeltaWing Le Mans bid
Discussion
It's a perfectly feasible car, just completely pointless!
It only exists as it "negates" some of the critical regulator requirements, and is being allowed to race as a prototype only. It has less drag than a conventional prototype, because it is allowed ride height and underfloor features banned for the existing cars, hence they need seperate exterior wings, and that means drag, whereas it produces downforce via underfloor aero, which is largely drag free. The shape itself is poor from a pure aerodynamic car (you want a wide front and a narrow back, the typical teardrop shape) rather than viseversa to enable decent pressure recovery in the vehicles wake.
In terms of tyre width, broadly speaking you need the tyre section in proportion to the axle mass, as F = MA, for the same A (lateral G) less M means less F and hence only needing narrow tyres. One thing the narrow track gives you is the requirement to run massive ARB rates to counteract the roll couple (but this can be tuned to some degree with the CofG and roll centres at the front). This could make the chassis difficult to tune to any given circuit.
Le Mans is still a high speed track (even with the chicanes) so it makes sense to run it here, where you effectively trade ulimate lateral G capability for reduced drag.
But you could do much better with an "Unregulated" conventional 4 wheeler with a much more even track.
Also, it's relevance to "road cars"??? Hey? What relevance, it has no relevance what so ever. The major OEM's have been running DI engines for years, making high specific outputs, they have optimised drag co-efficients within the required package envelope! That car would be impossible to homologate/type approve and hence even if it was the most aero dynamic car in the world, also completely pointless............
I wish the team the best of luck, they certianly will get some attention, but it's all smoke and mirrors (typical motorsport) and the end of the day ;-(
It only exists as it "negates" some of the critical regulator requirements, and is being allowed to race as a prototype only. It has less drag than a conventional prototype, because it is allowed ride height and underfloor features banned for the existing cars, hence they need seperate exterior wings, and that means drag, whereas it produces downforce via underfloor aero, which is largely drag free. The shape itself is poor from a pure aerodynamic car (you want a wide front and a narrow back, the typical teardrop shape) rather than viseversa to enable decent pressure recovery in the vehicles wake.
In terms of tyre width, broadly speaking you need the tyre section in proportion to the axle mass, as F = MA, for the same A (lateral G) less M means less F and hence only needing narrow tyres. One thing the narrow track gives you is the requirement to run massive ARB rates to counteract the roll couple (but this can be tuned to some degree with the CofG and roll centres at the front). This could make the chassis difficult to tune to any given circuit.
Le Mans is still a high speed track (even with the chicanes) so it makes sense to run it here, where you effectively trade ulimate lateral G capability for reduced drag.
But you could do much better with an "Unregulated" conventional 4 wheeler with a much more even track.
Also, it's relevance to "road cars"??? Hey? What relevance, it has no relevance what so ever. The major OEM's have been running DI engines for years, making high specific outputs, they have optimised drag co-efficients within the required package envelope! That car would be impossible to homologate/type approve and hence even if it was the most aero dynamic car in the world, also completely pointless............
I wish the team the best of luck, they certianly will get some attention, but it's all smoke and mirrors (typical motorsport) and the end of the day ;-(
noell35 said:
I can't help wondering what it would be like under braking with those skinny front tyres. Do Le Mans cars use ABS?
Read the stuff on the link I gave above to the Vigillante: very similar principle. All the weight is at the back, so even under fairly dramatic weight transfer under braking, the front tyres are not badly overloaded.Speedy11 said:
Please see this wonderful photoshop, not 
about what I mean
Surely any slight if any increase in drag would be more than offset by a better layout?
Surely you can see from your picture that you'd get about twice as much surface drag from the second layout? There being twice as much surface. about what I meanSurely any slight if any increase in drag would be more than offset by a better layout?
Sam_68 said:
Am I the only one to be reminded of the Vigillante Trivette?
Yes it does and i have post on other topics about the Trivette and Vigillante..
The Vigillante
The Trivette
Personal I love the idea of an update Trivette. If it can handle as well as claimed. As for a 200mph+ three wheeler, is Britain ready! Please visit www.vigillante.com
Read the Top Gear article and wonder.
Both are sadly out of production after the death of there create. Do any of you like the idea of putting an updated vision of these in production? (Could ten be sold a year?)
Edited by KDIcarmad on Tuesday 13th March 19:55
Max_Torque said:
One thing the narrow track gives you is the requirement to run massive ARB rates to counteract the roll couple (but this can be tuned to some degree with the CofG and roll centres at the front).
I assume that there will be bugger all roll resistance at the front, anyway - in that respect it will be dynamically similar to a three-wheeler; all the roll resistance will come from the 'two wheeled' end.If you look at the photos of the rear suspension, the upper wishbones seem to slope quite steeply upward, which tends to imply a high roll centre... which presumably means a very small roll couple and hence not much roll being propagated at that end?
It would be interesting to know how the front works: with a true three-wheeler, the front roll centre would be in the middle of the tyre contact patch at ground level, with no roll resistance, but the twin front wheels of the Deltawing allow alternatives.
Edited by Sam_68 on Tuesday 13th March 20:03
Max_Torque said:
The shape itself is poor from a pure aerodynamic car (you want a wide front and a narrow back, the typical teardrop shape) rather than viseversa to enable decent pressure recovery in the vehicles wake.
How come the kammback is such a popular design in the hybrid and 'ultra-efficient' markets? Is it basically just marketing and to allow boot space, or is there an aerodynamic thing that makes it good compared to the traditional teardrop?y2blade said:
Cyder said:
y2blade said:
WOW... I bet NISSAN wish they had all the PH experts telling them how to do it 
This place cracks me up sometimes!wst said:
ow come the kammback is such a popular design in the hybrid and 'ultra-efficient' markets? Is it basically just marketing and to allow boot space, or is there an aerodynamic thing that makes it good compared to the traditional teardrop?
In very basic terms, it comes down to the aspect ratio (length:width) of the teardrop.If you can make it long enough in relation to its width that the airflow remains attached, the teardrop is more efficient.
If the tail tapers too sharply, the airflow will detach and become turbulent, causing much more drag.
For a road car, making the 'teardrop' slender enough would mean having an impractically long, tapered tail, so you're better cutting your losses (and your tail
) with a Kamm arrangement.Speedy11 said:
y2blade said:
Cyder said:
y2blade said:
WOW... I bet NISSAN wish they had all the PH experts telling them how to do it
This place cracks me up sometimes!
All this discussion of teardrop forms is all well and good, but the vehicle would only be a tear drop shape in the airflow if it drove everywhere in reverse.
without seeing the underside of the car, which I presume is unlikely its impossible to comment on the cavity and side skirt arrangement that will give it downforce. Im also interested in the point made earlier that the lead wheels are far enough ahead of the CoG that they need only exert minor force to generate turning moment, when in the same post it is claimed that the distance from the drive wheels will lend it stability at speed (are the two not mutually exclusive)
(Hello by the way long time lurker recently rejoined after losing my original account through not posting that often - apologies if my input isnt needed)
without seeing the underside of the car, which I presume is unlikely its impossible to comment on the cavity and side skirt arrangement that will give it downforce. Im also interested in the point made earlier that the lead wheels are far enough ahead of the CoG that they need only exert minor force to generate turning moment, when in the same post it is claimed that the distance from the drive wheels will lend it stability at speed (are the two not mutually exclusive)
(Hello by the way long time lurker recently rejoined after losing my original account through not posting that often - apologies if my input isnt needed)
Northern Munkee said:
http://deltawingracing.com/2011/06/deltawing-24-he...
I just checked with mate of mine who works in a F1 team wind tunnel and with 76% downforce bias to the rear, it ought to understeer badly. I puzzle even such weight distribution, how there is not still weight transfer back to front under braking and turning in. Of course it could corner by voodoo. It's going to awkward to pass in an lmp2 which is quick in the corners, with DW guess braking distance will be longer, then it will come flying back down the next straight.
Reading the tech specs it's stability ought not to be a problem, I'm guessing the YouTube link is to the merc gtr? That was a large flat bottom area car.
Well according to the drivers it handles pretty well and going by the vids it looks pretty stable throughout the corner - as its not just aero balance that helps it turn but also vectoring off the back wheels.I just checked with mate of mine who works in a F1 team wind tunnel and with 76% downforce bias to the rear, it ought to understeer badly. I puzzle even such weight distribution, how there is not still weight transfer back to front under braking and turning in. Of course it could corner by voodoo. It's going to awkward to pass in an lmp2 which is quick in the corners, with DW guess braking distance will be longer, then it will come flying back down the next straight.
Reading the tech specs it's stability ought not to be a problem, I'm guessing the YouTube link is to the merc gtr? That was a large flat bottom area car.
As for braking the CG is very different to a normal racing car and so again its prob not far off a normal car.
It's got the WTF? factor that you see very rarely now. Reminds me of the first time I saw a Tryell 6 wheeler when I was a kid. The dinky model went straight to the top of the Christmas list that year. My 9 year old is equally excited about this one. Mind you I hope it works a bit better and goes a bit faster than the Tyrell..........
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