Delta Wing Discussion ONLY

[Machin]

As for how fast it might be given a full development program, nobody knows—it is all hypothesis. Nobody can rationally deny that it runs among the P2 competition with very limited testing and apparently iron tires.

You might well be right... Unfortunately there are too many variables to come to any firm conclusions.... even after the race we just won't know if the drivers were driving to perserve the car, what could be done with softer tyres, etc, etc...

....What we really need is a class for 500kg/300bhp/ground effects cars which allows Delta and rectangular cars to compete on even terms...

What can't be denied is that the Deltawing is a really aerodynamic shape:-as this chart shows.... (data derived from Deltawing data in May issue of Racecar Engineering, Group c data and LMP1 data from www.mulsannescorner.com).



The qustion is; do we believe that the Delta shape has no mechanical grip disadvantages as we are being told? I think it does have a disadvantage... but enough to counteract the aerodynamic advantage the Deltawing seems to have....? ....I think that all depends on the track... at Le Mans I think overall it actually might well be better than a 500kg/300bhp rectangular car.... but at a tight twisty track like Brands Hatch? I don't think it'll be quite so clear....

I've done some simulations to look at various different car configurations:-

Virtual Stopwatch -Deltawing
Virtual Stopwatch -Small Sports Racer & XJR-9

[optica]

It will be interesting to see how rigid the ACO are going to be about the DeltaWing's performance. It now looks as though achieving a 3.45 lap time might not be too challenging and it was already exceeding 300kph on test day. Will they be given drive-through penalties if they go too fast?....Perhaps they would be disqualified!! Hopefully it is all a bit arbitrary and stipulating a set of performance figures was just to give the developers an incentive to make sure it performs and ensure it wouldn't become a mobile chicane.... Is anyone better informed?

[Machin]

Originally Posted by optica

It will be interesting to see how rigid the ACO are going to be about the DeltaWing's performance.....Hopefully it is all a bit arbitrary and stipulating a set of performance figures was just to give the developers an incentive to make sure it performs and ensure it wouldn't become a mobile chicane.... Is anyone better informed?

I think you're right; I've read everything I can on Deltawing and I've not seen anything that says the team are limited to a 3.45 lap time or 300kph top speed; simply that these were aims when they were deciding what power to put in it....

.... if you do the sums you'll find that 300kph (or there abouts) is simply the physical limit for a car with 300bhp and having a drag of 550lbs at 90m/s as reported in Racecar Engineering Vol 22 No3.... there's no conspiracy or sandbagging here.

[aneesh99]

Originally Posted by Machin

I think you're right; I've read everything I can on Deltawing and I've not seen anything that says the team are limited to a 3.45 lap time or 300kph top speed; simply that these were aims when they were deciding what power to put in it.....

I'm pretty sure the ACO were very particular about the the lap time, Hindy was making a bit of a play when he was talking to Marino in the afternoon (at least I think it was the afternoon), everyone in the DW garage seemed to be pulling faces when Hindy suggested pushing harder... Take from it what you will but the guys on MWM have repeatedly said that the speed was limited at that they had to run to a set pace

[Machin]

"MWM"?

[joeb]

Originally Posted by Machin

I don't believe all this talk that the Deltawing is driving to a specified lap time... the whole idea of this is project is to prove the light weight/low power concept, right? If they have performance to spare, surely what they would do is down-tune the engine; tell the whole world about it and then achieve the same 3:45 lap time with even less horsepower... wouldn't they?

Originally Posted by Machin

I think you're right; I've read everything I can on Deltawing and I've not seen anything that says the team are limited to a 3.45 lap time or 300kph top speed; simply that these were aims when they were deciding what power to put in it....

.... if you do the sums you'll find that 300kph (or there abouts) is simply the physical limit for a car with 300bhp and having a drag of 550lbs at 90m/s as reported in Racecar Engineering Vol 22 No3.... there's no conspiracy or sandbagging here.

The ACO has specifically told the DW crew to keep laptimes around 3:45 and top speeds of 300kph. This has been reported in many places, here is one of them:
http://www.roadandtrack.com/racing/m...nt-and-testing

[Pandamasque]

Originally Posted by Machin

I think it does have a disadvantage... but enough to counteract the aerodynamic advantage the Deltawing seems to have....?

But does really have any aero advantage vs. a rectangular wing-shaped ground effect car?

Originally Posted by Machin

"MWM"?

http://radiolemans.0157.org/content/midweek-motorsport

[Adam43]

I suspect this is the usual misunderstanding over target lap times. Like the GT1 times in past years.

[bjohnsonsmith]

Originally Posted by Pandamasque

But does really have any aero advantage vs. a rectangular wing-shaped ground effect car?



http://radiolemans.0157.org/content/midweek-motorsport

Wings produce drag, particularly the rear wing, hence DRS in F1. If you can get the whole car to create downforce, rather than wings, so much the better.

[Articus]

ACO also wanted the LMPs to stay above 3:30

[Adam43]

So they will black flag the DW like they did they LMP1s in previous years.

[Articus]

[miatanut]

Originally Posted by R4z3rw33n

Except this car is the first in a string of 'different' designs - developed solely for the sake of varying from the norm (rather than improving on it).
'New', in that context, tends to imply there has been (or, will be) a progressive leap forward as a result.

You could argue (pretty reasonably) the aims of the DW, as a concept, could likely have been achieved (to a certain extent) via more conventional means of design.

I think the fact it beat four of the P2's using 2/3 of the horsepower speaks pretty loudly that it is a substantial improvement on the norm. But, the original program was the same speed with half the fuel consumption by achieving half the drag and half the weight. It has 2/3 the power of the P2's but it's achieving the same lap times. It has more than half the power of the P1's and it's not beating them. On that level it has fallen short of the original claim.

Still, this is a very different concept that has a minuscule amount of development and refinement relative to conventional solutions, and they have achieved a lot with it.

In a sense, they have refuted the old CanAm saying, because with a 450 HP engine, it would be mopping the floor with the other P2 cars. It's just at this point very early days for this concept with plenty of room for development, if allowed.

I would love to see ACO have a fuel consumption class with safety regulations and maximum dimensions, but no minimum weights. If the fuel economy were put where the DW is (or restricted a little more given the fuel restrictions coming under the new rules), initially cars in that class would be mucking around among the P2's, but at some point a large manufacturer (probably Audi would go first) would project they could win overall from that class and they would build a car to it. It would be very exciting to see a rivalry between the P1's and the fuel economy cars as the fuel economy cars became more refined and eventually the new triumphed over the old.

[Machin]

Originally Posted by joeb

The ACO has specifically told the DW crew to keep laptimes around 3:45 and top speeds of 300kph. This has been reported in many places, here is one of them:
http://www.roadandtrack.com/racing/m...nt-and-testing

that's a long article, so I quoted it for others to read;

the ACO has laid down a lap time for us‚ 3:45‚ which should be about in the middle of the LMP pack. But our top speed will be similar and our cornering speed will be similar.

I think you're reading too much into it... The 3:45 was a target time set by the ACO when they were designing the two seat version of Deltawing for Le Mans... its the reason they dropped the power to 300bhp... if they can do a 3;45 easily why don't they drop the power even more? That would make even more of a statement, wouldn't it?

[Machin]

Originally Posted by Pandamasque

But does really have any aero advantage vs. a rectangular wing-shaped ground effect car?

credit where credit is due... I can't find a rectangular car which can achieve a Cl of -1.5 whilst having a Cd of only 0.31.... and that includes Group C cars....



if you can I'd be keen to hear about it?

[gwyllion]

An interesting fact regarding the DeltaWing in the RCE Le Mans preview:

The team was forced to use wing mirrors on the car, though it had originally planned to use a Corvette style camera only. Using mirrors adds 8% more drag according to Ben Bowlby.

[chewymonster]

Not sure about that Cd, .31 is a decent figure for a long sedan with a windsheild and all that.

[miatanut]

Originally Posted by Machin

that's a long article, so I quoted it for others to read;



I think you're reading too much into it... The 3:45 was a target time set by the ACO when they were designing the two seat version of Deltawing for Le Mans... its the reason they dropped the power to 300bhp... if they can do a 3;45 easily why don't they drop the power even more? That would make even more of a statement, wouldn't it?

The original DeltaWing IndyCar proposal was 300HP:
http://www.seriouswheels.com/cars/20...ar-Concept.htm
So could they have reduced the power from the original concept?
I would say Highcroft's response would be the reason:
http://twitter.com/highcroftracing/s...01171364937729
If that's what the ACO wants, with time and money being very limited commodities, why not just stick to the original power level and bring it in right on the requested lap time?

It was kind of a miracle to get all this done in a year.

[MulsanneMike]

Originally Posted by chewymonster

Not sure about that Cd, .31 is a decent figure for a long sedan with a windsheild and all that.

My Nissan Versa has a .31 Cd. Decent by today's standard? In my opinion no, but that's an entirely different topic (consider for last 20 years show cars have been showing .14-.18--I blame the accountants and focus groups).

But for a contemporary race car, sure. In the 3.5 mile long Mulsanne day's the mid .3s were achievable with L/D in the 3:1 range. Pretty confident if so motivated you could achieve absolute drag figures close to that for perhaps not as high L/D as DW. DW's big "cheat" is the 20% lower frontal area. Other than that, give me free regulations regarding the underfloor and all bets are off.

For what it's worth, my own calculations show DW's .cd between .34 & .35.

[MulsanneMike]

Originally Posted by Machin

that's a long article, so I quoted it for others to read;



I think you're reading too much into it... The 3:45 was a target time set by the ACO when they were designing the two seat version of Deltawing for Le Mans... its the reason they dropped the power to 300bhp... if they can do a 3;45 easily why don't they drop the power even more? That would make even more of a statement, wouldn't it?

The 300 hp target was in lieu of the half, half, half aspects of the concept. If power starts to creep up, guess what, it will have as crappy MPG as an LMP1. Now it's MPG is only half as crappy.

[Machin]

Just for completeness I've added LMP1 data to my table:-



(Deltawing and LMP2 Figures taken from May and June issues of Racecar Engineering, and LMP1 aero figures based on Dome S102i data from www.mulsannescorner.com, except LMP frontal area which is estimated)

As someone else has pointed out previously; the one performance differentiator not shown here is the relative tyre coefficients.....

....Maybe they are running ultra hard tyres... and that's why they are 'slow' compared to what those numbers above suggest it should be capable of... to be honest if that means stopping for tyres half as often that can only be a good thing - I think tyre usage in top level motorsport is boarding on the criminal -how many sets get used in a current F1 weekend?

[MulsanneMike]

Originally Posted by Machin

Just for completeness I've added LMP1 data to my table:-



(Deltawing and LMP2 Figures taken from May and June issues of Racecar Engineering, and LMP1 aero figures based on Dome S102i data from www.mulsannescorner.com, except LMP frontal area which is estimated)

As someone else has pointed out previously; the one performance differentiator not shown here is the relative tyre coefficients.....

....Maybe they are running ultra hard tyres... and that's why they are 'slow' compared to what those numbers above suggest it should be capable of... to be honest if that means stopping for tyres half as often that can only be a good thing - I think tyre usage in top level motorsport is boarding on the criminal -how many sets get used in a current F1 weekend?

RCE's LMP2 numbers were generated from a fixed floor tunnel and have to be taken with a grain of salt. Drag's a tad on the high side for even an open top car. I'd expect to see around .58 in LM trim. Regarding the Dome numbers, 1185 lbs drag for a LM set up is extraordinarily high, by 200 lbs. The only caveat for the Dome numbers are they were map averages and not End Of Straight drag figures. EOS you'd expect drag to drop with lowered ride height. My preliminary calcs are indicating between .50 and .45 for a top flight LMP1.

[chewymonster]

Originally Posted by MulsanneMike

My Nissan Versa has a .31 Cd. Decent by today's standard? In my opinion no, but that's an entirely different topic (consider for last 20 years show cars have been showing .14-.18--I blame the accountants and focus groups).

But for a contemporary race car, sure. In the 3.5 mile long Mulsanne day's the mid .3s were achievable with L/D in the 3:1 range. Pretty confident if so motivated you could achieve absolute drag figures close to that for perhaps not as high L/D as DW. DW's big "cheat" is the 20% lower frontal area. Other than that, give me free regulations regarding the underfloor and all bets are off.

For what it's worth, my own calculations show DW's .cd between .34 & .35.

I haven't seen any practical designs that are better than a .26 or .25. Looks like the limit for a 5 passenger car. The GM EV1 is .19 but doesn't look that good and not super practical either (two seats only and a greenhouse not so suitable for modern crash tests) VW is about to release something with a sub .20 cd as well and pretty cool looking but likewise not mainstream practical. I suppose something between .2 and .25 with 5 seats is possible but it won't be that great looking.

As for the Delta Wing, certainly it's packing a decent amount more horsepower than 1/2 of LMP2 horsepower. The engine displacements are quite close too. Would be interesting if it does get double the mpg of an LMP1 as the hype/hope is. Of course Audi would likely up their mpg somewhat simply by taking it easy and running a 30 second slower lap.

[gregtummer]

Originally Posted by miatanut

I would love to see ACO have a fuel consumption class with safety regulations and maximum dimensions, but no minimum weights. If the fuel economy were put where the DW is (or restricted a little more given the fuel restrictions coming under the new rules), initially cars in that class would be mucking around among the P2's, but at some point a large manufacturer (probably Audi would go first) would project they could win overall from that class and they would build a car to it. It would be very exciting to see a rivalry between the P1's and the fuel economy cars as the fuel economy cars became more refined and eventually the new triumphed over the old.

That would be interesting as Audi already has their 2012 car with a weight of 750kg I believe. They are running around 150kg of ballast.

[gwyllion]

Originally Posted by Machin

Just for completeness I've added LMP1 data to my table:-

Your power number for LMP1 is a bit low.

According to OAK Racing the Judd LMP1 produces 540 bhp.
Mike's sources say that the Toyota TS030 engine produces 560-570 hp.
The Audi R18 engine probably has in the direction of 600 hp.