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Aero points should be pro-rated to weight


mender
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3 hours ago, mender said:

I have a fairly extensive technical library that has a lot of first or early editions of everything I could buy starting in the mid-70s.  Back then, books on racing tech and technique were quite rare, not like today where you can go on Amazon and order up a couple dozen.

 

My books of Smith's series are quite dog-eared, as are my two copies of "Sunday Driver" which includes the story of the Cannonball with Oscar Koveleski's entry. Classic, and thanks for mentioning that!

 

P.S. Looks like my Ayrton Senna book is now worth a bit of money...

I figured a few of us older racers would remember the old days, I was a bit of a victim of Showroom Stock racing and not having the rules so lax on Aero, my library contains all the Smith books and the Unfair Advantage, great reading and informative. The proof is the fact my car completed both race days and the test day running flawless all three! Though fairly slowly, really looking to April's race now! But we are in different even better days with this web thing to access now.😊

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Posted (edited)

Just for fun, I counted up the books in my racing and car tech library, not counting manuals: just over 180. They make up less than 10% of the books that I own (haven't counted those lately), most of which I've read several times. Pretty good science fiction section, probably about half of the total.

 

I'm really glad I don't pay by the hour for internet these days... 

 

I read - a lot. :)

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8 minutes ago, mender said:

Just for fun, I counted up the books in my racing and car tech library, not counting manuals: just over 180. They make up less than 10% of the books that I own (haven't counted those lately), most of which I've read several times. Pretty good science fiction section, probably about half of the total.

 

I'm really glad I don't pay by the hour for internet these days... 

 

I read - a lot. :)

Knowledge is power! As number 5 said "need more input".🙂

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20 hours ago, Bandit said:

Solstice-460 points, Sky-500 pts, CTS 480-500 pts 🙂

Solstice / sky no equal miata

CTS no equal e30 or e36

 

Typical American cars overweight and overbig.  

Edited by wvumtnbkr
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Posted (edited)
16 hours ago, Timothy G. Elliott said:

Any of you ever read the Engineer to Win series? It's always more beneficial to lower drag and easier to do by upgrading on Aero mods, then adding Horse power. We were hitting a literal wall at Road America and I failed to recognize the benefits of Aero mods allowed in our series, so now I've done a bunch, though the proof will be at April's race. They were not hard and should improve our lap times hopefully by a lot.👍

IMG_20201227_104009712_HDR.jpg

Back to wings 'n things.

 

I was going to try the same rear wing that you have but I wasn't sure it would be enough to balance the front splitter. I didn't know how well the splitter would work and as a result how much rear aero would be needed to keep the car out of oversteer at higher speeds. I opted to put on the rather large wing that I bought at a swap meet for $35 and set it up for a good range of quickly adjustable angle of attack. I was even considering making it active later but likely won't now that I've had a chance to test it.

 

As things turned out, my drivers liked the wing in its initial full angle setting so much that when I suggested some tuning they told me not to touch it, that they all loved it just the way it was. Fine, less work for me!

 

Here's a video from another car of the race that we were at two months ago with a couple short appearances of the Civic doing the underpowered but over-aero-ed method of not slowing for corners and passing more powerful cars on the inside or outside regardless of where those cars are in the corner. First appearance is at about 4:40 with an off-throttle slight oversteer around the outside showing the ability to put the car off-line and not lose it, something the camera car tried at 5:00.  Then around 5:40 the Civic did more passing in the second stint but with more conventional usage of the car's extra traction by driving by and away. The size of the Civic's wing received a lot of attention and some ridicule - but only before we went out on track. Not much said about it afterwards. ;)

 

 

 

The white 787 Miata that is featured for a fair bit of the clip won the Saturday race and also shows the power vs aero battle quite well. Note that the red RX7 that they were both doing battle with snuck by just before we arrived on scene but it didn't slow us down much. Great track!

Edited by mender
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1 hour ago, wvumtnbkr said:

Solstice-460 points, Sky-500 pts, CTS 480-500 pts 

 

1 hour ago, wvumtnbkr said:

Solstice / sky no equal miata

CTS no equal e30 or e36

 

Typical American cars overweight and overbig.  

2009 Miata-400 points Earlier ones are 300.

E30-450

E36-485

 

Hmmmmmm.....

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16 minutes ago, Bandit said:

 

2009 Miata-400 points Earlier ones are 300.

E30-450

E36-485

 

Hmmmmmm.....

I meant in relation to weight and size.

 

The nc miata is not raced much and IS very close to a solstice.  Overweight and overbig.

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14 minutes ago, wvumtnbkr said:

I meant in relation to weight and size.

 

The nc miata is not raced much and IS very close to a solstice.  Overweight and overbig.

Sounds like that is going to be changing after the one showed up to VIR and did so well.....I know of 3 teams planning on building them now.  I will admit the guys that built it know what they are doing, but it did truly show off the potential of a well executed build.

 

I could see with continued entries  and data, the VPI going up to match the e30, even possibly the e36.  2000ish lbs, 170ish hp, but only ~15 gallons with a cell.

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3 minutes ago, hotchkis23 said:

Sounds like that is going to be changing after the one showed up to VIR and did so well.....I know of 3 teams planning on building them now.  I will admit the guys that built it know what they are doing, but it did truly show off the potential of a well executed build.

 

I could see with continued entries  and data, the VPI going up to match the e30, even possibly the e36.  2000ish lbs, 170ish hp, but only ~15 gallons with a cell.

Oh yea, I didn't mean it can't be competitive.  Just saying they are big and heavy for a miata.  The nc matches up pretty well with a solstice.

 

My point was that there aren't too many domestics that are light tossable rwd cars. 

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Mender loved the video, and saw the white Rabbit a few times too, they have some Aero on that one... Wonder how they did? Looks like 14th overall and 2nd in class I could live with that! 😂

Edited by Timothy G. Elliott
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On 12/31/2020 at 8:30 AM, wvumtnbkr said:

What about the 1.8 miata that was tearing it up at road America?

 

What about huggies cars that 1 is swapped and the other has aero and they have very similar race pace?

 

I mean obviously more horsepower is better, but there is definitely a crossover where "some more horsepower" is not as effective as aero.

 

Also, horsepower costs more in points than a splitter, airdam, and wing (30 pts).  How much hp can you buy for 30 points?  You could get a couple seconds a lap for those 30 pts.

Horsepower is good, but more time is made up in the corners than the straights generally. Downforce, the aero being talked about here it seems, can have a huge impact on lap times. Much more than a couple seconds a lap.

 

I don't have exact figures in front of me, Mender can probably calculate them (and of course it is track specific), but if car A is 20 mph faster at the end of the straights than car B yet is 10MPH slower than car B through the corners car A will generally lose on lap time.

 

One will do better improving their speed in the slowest sections of the track versus focusing on the fastest portion because you spend less time with your foot through the firewall than you did braking and cornering. A skilled driver will often beat a "faster" car because he gets through the corners better, not because he's better at holding the loud pedal down.

 

A 435hp Cougar ran at RA and didn't set fast lap. Was pretty impressive in a straight line however.

 

A good example outside of racing is Amtrak on the Northeast Corridor. They found raising a 30 mph section of track through a congested area to 50mph allowed them to reduce the schedule more than raising the top speed from 130 to 150. Was a lot cheaper too. Much like racing.

Edited by Bandit
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2 hours ago, wvumtnbkr said:

Yep, exactly.  Hp is nice, but aero and suspension work seems to help lap time more (to an extent).

A good example from my past was running an 84F Reynard Formula Ford, it was a brick aerodynamically, but working on spring rates and shock valving alone, made it faster then the Swift's at Blackhawk Farms raceway in a 2000 National race there. At Road America the Swift's had a huge Aero advantage and we're 4 or 5 seconds a lap faster!

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7 hours ago, Bandit said:

Horsepower is good, but more time is made up in the corners than the straights generally. Downforce, the aero being talked about here it seems, can have a huge impact on lap times. Much more than a couple seconds a lap.

 

I don't have exact figures in front of me, Mender can probably calculate them (and of course it is track specific), but if car A is 20 mph faster at the end of the straights than car B yet is 10MPH slower than car B through the corners car A will generally lose on lap time.

 

One will do better improving their speed in the slowest sections of the track versus focusing on the fastest portion because you spend less time with your foot through the firewall than you did braking and cornering. A skilled driver will often beat a "faster" car because he gets through the corners better, not because he's better at holding the loud pedal down.

 

A 360hp Cougar ran at RA and didn't set fast lap. Was pretty impressive in a straight line however. The Cougar could out brake almost any car on the track. The Cougar was 1k lbs heavier than most of the cars but was well sorted in the handling department. The Cougar’s biggest advantage was ability to go 2 hours on fuel at a big track like R.A. The team had an off in the last hour Saturday and finished the race in 3rd gear only. The Porsche obliterated the Cougar in every phase of the race. Except Fuel capacity and economy.

 

A good example outside of racing is Amtrak on the Northeast Corridor. They found raising a 30 mph section of track through a congested area to 50mph allowed them to reduce the schedule more than raising the top speed from 130 to 150. Was a lot cheaper too. Much like racing.


 

Fixed it for you. 

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Posted (edited)
11 hours ago, Timothy G. Elliott said:

Mender loved the video, and saw the white Rabbit a few times too, they have some Aero on that one... Wonder how they did? Looks like 14th overall and 2nd in class I could live with that! 😂

You might like this one from the inside of the Rabbit, might even pretend you're driving! 

 

Everyone is learning the track, it was very early in the race so don't judge too harshly. My first driver shows up in the rear view mirror at about 9:50. You can see him get left for dead on the corner exits when he doesn't carry the mid-corner speed (10:20, 11:05, 12:20) but can hold on to the position when he does carry the speed (13:00, didn't leave racing room at 13:20 so sorry to #27, 13:40).

 

 

This track definitely favoured the Civic, lots of fast corners that could be taken without lifting as compared to what you can hear the #27 Rabbit doing. Aero trumps power on this one. :)

Edited by mender
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Posted (edited)
14 hours ago, Bandit said:

I don't have exact figures in front of me, Mender can probably calculate them (and of course it is track specific), but if car A is 20 mph faster at the end of the straights than car B yet is 10MPH slower than car B through the corners car A will generally lose on lap time.

The key is that it doesn't take much increase in average speed to give a noticable drop in lap time. 

 

On a 3 mile track, 2:30 is an average speed of 72 mph. By increasing the cornering speed by say 3 mph and carrying that difference most of the way down the straights, the average speed should now be around 74.5 mph and would give a 2:24.95 lap time. 5 seconds quicker.

 

More power starts from a zero speed advantage out of the corner, becomes significant about half-way down the straight, and reaches a peak just after the earlier braking point. There may be some other sections where the extra power can get the car up to speed but most of the advantage will be on the long straights. They have to be long enough to build a significant speed difference.

 

Let's say that the top speed difference is double the cornering speed difference to stay with your 2:1 proportion, so the power car was 6 mph faster at the end of the straight. That means that the extra power gave an average speed difference of 3 mph, but only on the straights. I timed the video above and got about 40% straight time (generous) for an average of 1.2 mph faster and a lap time of 2:27.54. 2.5 seconds quicker; advantage to aero car of 2.5 seconds. 

 

The main difference: higher cornering speed is an advantage on all the corners and all the straights, but power is an advantage mostly on the last half of the long straights. The split between corners and straights on the track will factor in as well, as you mentioned.

 

Your math may vary. :)

Edited by mender
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Posted (edited)

Okay, a bit more math. ;)

 

Let's decrease the aero car's cornering speed increase to get the same lap time as the power car. That would be 1.5 mph, or a 1:4 ratio to the power car's 6 mph. Now let's see what percentage performance increase is needed for each of those two changes.

 

Cornering speed: let's say the average cornering speed is 60 mph. 60 + 1.5 = 61.5 mph, /60 = 1.025. Square that to get the needed increase in cornering gs and the result is 5% more force. 5% of 2350 lbs = 120 lbs downforce, should be doable with a splitter, air dam, and rear wing or 30 points.

 

More top speed: let's say the average speed increase on a long straight is 40 mph before the power increase. 40 + 6 = 46 mph new speed difference on the straight, /40 = 1.15 or 15% more speed increase. To accelerate to a 15% higher top speed in the same time would take 15% more power (actually more because of aero drag but good enough for now). The car has to achieve that higher speed in the same distance as before but less time because the average speed is now higher down the straight. I'll just guess and say that the car needs 18% more power.

 

Using 160 hp as the baseline, the engine now needs to produce 189 hp. To use a popular car as an example, an engine swap from 168 hp to 189hp in an E30 is worth 50 points or 20 points more than the aero, plus now uses more fuel. Advantage: aero car. Less points, less fuel usage, same lap time.  It's like getting 3 gallons more fuel for -20 points compared to the swapped car. :)

 

Again, your math may vary. Since aero is very speed sensitive, a track with high speed corners will be better for the aero car than a slow track.

Edited by mender
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Posted (edited)
On 12/31/2020 at 10:01 AM, enginerd said:

On topic, wing / splitter are limited to the width of the car. Domestics are often wider than imports. Wider wing, more downforce, advantage domestic.

 

Also there's no rule on wing chord or profile. You can put a really big wing on your domestic... doesn't have to be the same wing that someone else puts on their miata.

1990 Camaro width: 72.5"

1990 Mustang width: 68.3"

1990 Civic width: 66.3"

 

1990 Camaro swap weight: 3026 lbs

1990 Mustang swap weight: 2570 lbs

1990 Civic swap weight: 2181 lbs

 

 

Camaro to Civic: 9.3% width difference; 38.7% weight difference.

Mustang to Civic: 3% width difference; 18% weight difference.

 

Advantage: import.

 

P.S. I put a really big wing on my import. :)

Edited by mender
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That's what I've believed. And as an additional note Aero improvements take less to create greater gains. We are fighting an invisible wall when dealing with airflow and small gains benefit in quicker lap times then trying to increase HP.

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7 hours ago, mender said:

You might like this one from the inside of the Rabbit, might even pretend you're driving! 

 

Everyone is learning the track, it was very early in the race so don't judge too harshly. My first driver shows up in the rear view mirror at about 9:50. You can see him get left for dead on the corner exits when he doesn't carry the mid-corner speed (10:20, 11:05, 12:20) but can hold on to the position when he does carry the speed (13:00, didn't leave racing room at 13:20 so sorry to #27, 13:40).

 

 

This track definitely favoured the Civic, lots of fast corners that could be taken without lifting as compared to what you can hear the #27 Rabbit doing. Aero trumps power on this one. :)

Even better video got to love this day and age, I could learn this track just watching these Videos!

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On 12/31/2020 at 2:23 AM, mender said:

200 lbs of aero on 2000 lb car vs 3000 lb car. Another disadvantage for domestics.

 

Aaaand go. :)

Heavier cars are usually also physically larger. More aero surface area to generate downforce. Think modern f1 cars, huge compared to the v8 v10 cars

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23 minutes ago, wd6681 said:

Heavier cars are usually also physically larger. More aero surface area to generate downforce. Think modern f1 cars, huge compared to the v8 v10 cars

Camaro to Civic: 9.3% width difference; 38.7% weight difference.

 

The static weight is trying to throw the car to the outside of the track. A 9.3% wider wing isn't going to come close to totally offsetting the 38.7% greater weight that wants to go straight. Wider tires will help somewhat but the typical 275 run on a bigger car is only about 11% wider than the 245's run on smaller cars. Acceleration, cornering and braking are all negatively effected by weight.

 

Other than having 4 tires a F1 car has next to nothing in common with production car aerodynamics.

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9 hours ago, mender said:

You might like this one from the inside of the Rabbit, might even pretend you're driving! 

 

Everyone is learning the track, it was very early in the race so don't judge too harshly. My first driver shows up in the rear view mirror at about 9:50. You can see him get left for dead on the corner exits when he doesn't carry the mid-corner speed (10:20, 11:05, 12:20) but can hold on to the position when he does carry the speed (13:00, didn't leave racing room at 13:20 so sorry to #27, 13:40).

 

 

This track definitely favoured the Civic, lots of fast corners that could be taken without lifting as compared to what you can hear the #27 Rabbit doing. Aero trumps power on this one. :)

Was thinking that Rabbit had some serious beans under the hood until I noted the KPH on the speedo.... Canucks...

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1 hour ago, Bandit said:

Was thinking that Rabbit had some serious beans under the hood until I noted the KPH on the speedo.... Canucks...

Ana hey, just checked and I saw about 105 mph at Road America with our car, they were right in there with their KPH stuff!😁 The GTI should be able to get to 115, it can do that unloaded on the lift with the gear box that's in it, hoping the Aero will get it there! Here's the link to the PRDA website with Oscar with his helmet on. http://www.a2zracer.com/page24.html

Edited by Timothy G. Elliott
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On 12/31/2020 at 8:00 AM, The Aero Man said:

I have never seen a scale of any kind at the track during a champcar event, ever. If we're bringing scales, just grab the trailer dyno and we can have on site dynoing for power to weight ratios.

 

Also, not all aero is the same. Cars would be required to have a data acquisition system and sensors to determine downforce - this could possibly be done with a modified flagtronics, but it is just a hassle. A zip tie around the shock absorber is almost the least thought through idea I've ever heard of.

 

Even though my car has 50pts of aero on it, we only make about 50 lbs of downforce at 100mph.

 

You could also just make your car lighter so your downforce has more effect on the car.

No scales or data needed, just use the swap calculator "weights" and calculate the aero points based on that.

 

If Champcar thinks it's good enough for power to weight, it's certainly good enough for aero to weight.

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