Deltawing physics discussion

Keep it civil please.

OK I've thought about this a bunch. Does the deltawing concept work? I mean if we prepare identical weight cars one a traditional fendered sports racer the other a deltawing @ say 1200lbs with the same 300hp powerplant which would be faster around a given course?

Its difficult for me to understand the handling advantage of the deltawing. It would seem total front grip may be slightly higher on the DW due to less loading on the outside wheel. However as a percentage of the static weight the DW would experience a much higher % WT (due to WT effectively reducing to Mass*CGht/TW). Tire coefficients of friction generally decreases with increased weight meaning for a givem increase of weight you get a less than 1.0 increase in grip. In the rear with the DW you are managing more weight than the traditional car so I would imagine the ultimate grip would be lower than what is possible with a traditonnal chassis.

Acceleration when grip limited would be superior with the deltawing. I am not buying that a traditional car would have a higher frontal area than the DW but may have a worse COD although they may not. Again comparing cars of same weight/power. Anyone have any insight here?

Braking performance does not seem that either chassis would have much advantage. It is possible the potential directional authority afforded to the DW chassis may provide an advantage over the reduced authority allowed in a traditional chassis with 10+% more front weight, narrower rear track, and wider front tires. The DW may have an advantage here over a traditional car equipped with equivalent stability/traction control technologies.

I'm just wondering what people think of the math behind the DW. Most of what I have found has danced around comparisons to identical spec cars. To me that is the most important thing. I can destroy a formula vee if I present an alternative car that allows specifications not afforded to the FV but that doesn't proove my chassis outright superiority.

Most of the concepts are beyond my comprehension but I found the interview Chris Harris did with the designer very interesting. Especially the way they handled increasing the role damping in the rear.

https://www.youtube.com/watch?v=c_INdbXMqsw

I would be willing to put money on a "square" chassis. I cant remember what, if anything, the wing has been faster than on a track. Ill try to get some numbers. And just to say, but that's the highest horse 300hp engine ever :)

I have not seen anything that the wing has done which makes me think, "hmmmm, they are onto something." I looked through the initial design and the numbers they say and theoretically it could be an awesome car. The problem is that it seems the car doesn't produce.

It's barely been faster than the P2 cars at tracks with long straights. On handling tracks, it's barely faster than the fastest LMPC car. And it's running in P1.

Is there a Porsche near by that's gonna punt you into a corner?

I think there is a lot of incomprehension about the Deltawing. It's purpose was not to make a faster car, but a more efficient one, mostly throught aerodynamics. The goal was to make a great aerodynamic shape, and then see if the resulting configuration could be made to handle and stop like a conventional car. And it did. Its advantage on the race track was that it had great fuel consumption that allowed for fewer pit stops. Which is a huge deal in endurance racing.

Edit. The fact that a brand new configuration was competitive against configurations that have been in development for a 100 years, shows that it was a good concept.

But I didn't answer the OP's question about the physical aspect of the DW. To understand it physically, I like to use the airplane comparaison. While a normal car tries to spread the load as evenly as possible between each tires, the DW is a bit like a canard airplane. It uses its rear tires to do the bulk of the work, and the front tires are simply there for control. vs

For it to work, you need a very rear CG, which is a good thing for acceleration and braking. And by not limiting himself to the "one wheel at each corner" configuration, the cornering becomes a simple math problem. With this configuration, you need to pay particular attention to the rear suspension because it does all the work.

fanfoy wrote: I think there is a lot of incomprehension about the Deltawing. It's purpose was not to make a faster car, but a more efficient one, mostly throught aerodynamics. The goal was to make a great aerodynamic shape, and then see if the resulting configuration could be made to handle and stop like a conventional car. And it did. Its advantage on the race track was that it had great fuel consumption that allowed for fewer pit stops. Which is a huge deal in endurance racing. Edit. The fact that a brand new configuration was competitive against configurations that have been in development for a 100 years, shows that it was a good concept.

So they need to find a middle ground?

fanfoy wrote: It's purpose was not to make a faster car, but a more efficient one, mostly throught aerodynamics.

I think that's where the OP's question is a good one: if it is more efficient, it should be faster with the same power, or as fast with some lower amount of power.

I won't say that you're wrong that being close with less development suggests promise, but proof of anything doesn't come 'til success is achieved. And I think it's fair to define success in the terms above: faster with the same power, or as fast from less. Being very close would seem to be reason to continue development in search of success/proof.

Anything short of that sidesteps the question.

fanfoy wrote: It's purpose was not to make a faster car, but a more efficient one, mostly throught aerodynamics.

But is the end result necessarily any better than a clean-sheet (outside of current rules) design 'square' track car that returns the focus back on aero efficiency rather than downforce, even though sacrificing aero efficiency for downforce is what has proven to win races for decades now?

The goal was to create a shape that carried more negative lift in its inherent design rather than tacking a whole bunch of wings on a car and adding a lot more drag.

Is there some inherent property that makes a narrow front track vehicle able to produce more negative lift, without the drag penalty of wings, than an equivalently designed square track vehicle?

IIRC, the shape they chose combines low frontal area for reduced drag along with some tricky air management under the car. The combination creates a vehicle with less lift so the car employs less chicanery to create negative lift.

The comparison with P2 or P1 is pretty much meaningless, IMHO. P1 and P2 are heavily restricted by rules in terms of how much aero they get, minimum weights, tire sizes, front area, fuel capacity, etc, etc. Experimental cars like the deltawing aren't, they're pretty much only limited by physics and imagination.

On the aerodynamic front, you can sort of understand the shape if you look at the current conventional cars. The problem, aerodynamically, of current cars is the front wheels. They need to be as fas forward as possible for chassis balance reason. But that really screws-up the aero. If you look at them, all they are trying to do is manage the damage in that area, by getting it over with as fast and cleanly as possible. For example: If you look at that image, take of the front wheels, and you end up with a DW kind of shape.

In reply to ransom: a more aerodynamic efficient shape will not produce a faster car around a circuit. It has been proven time and again that a high-downforce/draggy car is faster around a circuit. As far as speed is concerned, the efficient aero should only produce a higher top speed at the end of the straight which is worth very little time. But the clean aero make a significant difference on fuel consumption.

But you are right, this is all theory, and until it is proven, it will stay like that. Sadly, motorsport hasn't embraced radical new ideas historically, so we'll never know. And since this shape as no practical application (the CG location is too critical), we'll probably never know for sure.

I thought the other part of the equation was lighter weight as well.

I am not sure how much lighter a DW would be over a "square car", but it MAY be significant.

Rob R.

However the Frontal area is identical so the COD must be significantly worse for traditional cars than the DW. I've looked for a COD claim for the deltawing and can't find one can anyone else? I'm not sure a comparable traditional car has been developed to the extent that the DW has.

To my knowledge there is not a racing class that allows a ~1000lb car with 350hp to exist/race other than special allowances for the DW. That said we can compare the lap times on some courses to SCCA CSR cars which have ~250hp and weigh 1250lbs or 570kg. The Deltawing ran at Road America this summer at 1:55.362 @ 590Kg/350hp. The CSR record at Road America is 1:59.6XX. I'm not sure what an extra 100hp for a CSR car would do but It may overcome the 4.3 second differential.
The reduced weight is super critical because it allows the car to achieve the same cornering G's with less downforce. In the /Drive video they claim 4g's of cornering in 1 turn @ Road Atlanta. The laptimes the DW where turning where comparable to those of other P1/P2 cars so I do not believe it's cornering speeds where radically different so we can assume that a P1/P2 car cornered at a similar 4g's a that corner. To do that the DW would need to produce a minimum of 2x it's weight in downforce or ~1200kg. A P1 car would need to produce ~2000kg of downforce to generate the same cornering speed. Producing this much greater amount of downforce does more to me to explain the efficiency of the deltawing than simply not having nacels over a traditional width front axle. Does anyone have any further thoughts on this (Amount of downforce required to produce a given cornering speed and the impact of drag).

Also not all LMP type cars run the abrupt front end of the Audi's.

I would like to see a class provisionally ran that allows teams to produce a P1/P2 type car to the same specs as the Deltawing. 590KG weight, 350HP otherwise fairly open ruleset. I'm not sure there would be money in it for the team running against the DW. Overall I feel like the DW has simply figured out a great marketing message and has pushed it's "innovation" message to the point that the public that has interest in such things is convinced that it's running heads up with P1/P2 cars at 1/2 the HP, Must be Wizzardry. I would love to find out for real what if any advantage it has.

wvumtnbkr wrote: I thought the other part of the equation was lighter weight as well. I am not sure how much lighter a DW would be over a "square car", but it MAY be significant. Rob R.

I'm not sure it would be any lighter. 500-600kg formula cars with bezerk HP are not uncommon. F1 cars are 642kg with 950hp, Formula Atlantic cars are 560kg with a Automotive 4-cylinder.

A DSR ran 1:59 at Road America during the Runoffs in 2012. It was the first SCCA club car to do so. It ran a turbocharged 600cc Suzuki GSX-R motor.

fanfoy wrote: In reply to ransom: a more aerodynamic efficient shape will not produce a faster car around a circuit. It has been proven time and again that a high-downforce/draggy car is faster around a circuit. As far as speed is concerned, the efficient aero should only produce a higher top speed at the end of the straight which is worth very little time. But the clean aero make a significant difference on fuel consumption.

That depends on how you define efficiency; making more downforce for a given amount of drag or creating less drag for a given amount of downforce is a more useful form of aerodynamic efficiency for a racecar than simply a lack of drag. I believe the term "lift/drag ratio" applies.

fanfoy wrote: But you are right, this is all theory, and until it is proven, it will stay like that. Sadly, motorsport hasn't embraced radical new ideas historically, so we'll never know. And since this shape as no practical application (the CG location is too critical), we'll probably never know for sure.

I sound like part of a broken-record chorus, but I think this thing is a question in search of an answer. It's a sort-of-interesting anomaly, but it doesn't make for a very useful car for road or circuit. It's almost as though it's in the wrong arena: like they should have built a deltawing land speed car, or hypermiler, if low drag and weight were the extent of their assertions.

Or maybe it's just still misunderstood. Honestly, I wasn't under the impression that their efficiency was all about drag reduction; I thought it was supposed to be a more balanced circuit racer package, but I also haven't paid as much attention to it as you have.

If it was never meant to be compared apples to apples with a conventional racecar, they've fallen short if nowhere else in failing to talk about what frame of reference it should be viewed in. But to come full circle, if it is supposed to have some advantage over a standard car, there has to be some opportunity for direct comparison.

In reply to fanfoy:

I think it hasn't been embraced because it is dangerous to be around on the race track.....Nissan definitely didn't help that by painting it flat black followed by chrome.

racerfink wrote: It's barely been faster than the P2 cars at tracks with long straights. On handling tracks, it's barely faster than the fastest LMPC car. And it's running in P1.

it was placed in P1 … does that mean that it should be there ?

the fact that it runs times comparable to P2/LMPC says to me that that is where it should be … then the efficiency part would really come into play …

a few yrs ago a Civic(or maybe a Fit) won the 13hr at VIR even though it was running much slower lap times than the runner up(s) …. it made many fewer pit stops

fanfoy wrote: The problem, aerodynamically, of current cars is the front wheels.

Which method typically produces a lower drag coefficient: An object that is blunt at the front and tapers inward towards the rear, or an object that it pointed at the front and tapers outward towards the rear?

To me this indicates that, given an clean-sheet design with an open/unwritten rule set, the front wheels are not necessarily 'the problem' for creating an aerodynamically efficient car.

Just wait until they win a race. then all cars will be delta wings. this is the norm for auto racing.

iceracer wrote: Just wait until they win a race. then all cars will be delta wings. this is the norm for auto racing.

As soon as Connie Swingle and Don Garlits figured out the formula for rear engine Top Fuel dragsters and won with it, the front-engined cars were doomed. One year later, there were no major front-engined cars left.

Lotus brings an underpowered rear-engined car (plus Jim Clark) to Indy and changes Indy when the combination wins.

NASA has experimented with "lifting bodies" for years. I'm surprised it took this long for someone to take the same idea and turn it upside down.