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Re: Suggestions for design undertray
Posted: 30 Mar 2022, 02:25
by PhillipM
Apart from a tiny amount of toe out would have such a drastic effect on the tyres, life and grip and almost nothing on the aero.
The aero is there to load the tyres and help them out, not vice versa.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 04:32
by godlameroso
PhillipM wrote: ↑30 Mar 2022, 02:25
Apart from a tiny amount of toe out would have such a drastic effect on the tyres, life and grip and almost nothing on the aero.
The aero is there to load the tyres and help them out, not vice versa.
You can safely use around half a degree of toe out without affecting tire life, contact patch is not affected by toe, only camber. Last generation cars used a lot of toe out, you could tell from the outer edge blistering in some races in 2018.
Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 09:03
by Tommy Cookers
godlameroso wrote: ↑30 Mar 2022, 04:32
Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?
yet more of godl's nonsense !
half a degree of toe is roughly 5mm
toe is slip
with half a degree of slip the tyre will generate roughly 0.5 - 1 'g' worth of side-force - that's a lot of force
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 12:42
by godlameroso
Tommy Cookers wrote: ↑30 Mar 2022, 09:03
godlameroso wrote: ↑30 Mar 2022, 04:32
Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?
yet more of godl's nonsense !
half a degree of toe is roughly 5mm
toe is slip
with half a degree of slip the tyre will generate roughly 0.5 - 1 'g' worth of side-force - that's a lot of force
We are both wrong.
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.
And if both tires have the same toe there is zero thrust steer.
If what I say is nonsense then how come I was right about the Mercedes car not being very good?
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 13:11
by Tzk
Fluido wrote: ↑29 Mar 2022, 15:56
So basicly all the area(red area) from front to back wheels is useless?
No, it's not. Don't look at every part of the floor separately. The diffusor can still suck air in from the sides and air can still travel outside behind the frontwheels.
There's no perfect guide you can follow to get a good floor. It's always a function of the general shape of the car as well as the wing you want to use and other flow conditioners around the car.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 13:29
by PhillipM
godlameroso wrote: ↑30 Mar 2022, 04:32
PhillipM wrote: ↑30 Mar 2022, 02:25
Apart from a tiny amount of toe out would have such a drastic effect on the tyres, life and grip and almost nothing on the aero.
The aero is there to load the tyres and help them out, not vice versa.
You can safely use around half a degree of toe out without affecting tire life, contact patch is not affected by toe, only camber. Last generation cars used a lot of toe out, you could tell from the outer edge blistering in some races in 2018.
Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?
One, your maths is massively out.
Two, toe out blisters the inner tire edge, not the outer.
Three, half a degree of toe out is massive.
Four, the last generation of cars were almost exclusively running toe in on the rear and toe out on the front. The only exception was some of the Monaco spec setups.
Five, toe settings generate more heat and wear than the camber settings you'd run sensibly ever does, by an order of magnitude
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 13:32
by PhillipM
godlameroso wrote: ↑30 Mar 2022, 12:42
We are both wrong.
https://robrobinette.com/images/S2000/A ... anual4.jpg
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.
And if both tires have the same toe there is zero thrust steer.
If what I say is nonsense then how come I was right about the Mercedes car not being very good?
You do realise those numbers only apply for the S2000 with that specific wheel and tyre combo, right? You can't just nick the numbers out of your service manual and expect them to apply to every vehicle?
Any sort of performance car needing a full length diffuser is going to be on slicks that generate peak grip at a couple percent of slip, not the 8-10% of a road tyre.
So yes, adding half a degree to the rear tyres of toe out to generate tenths of a percent of aero loading extra is pretty insane.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 13:38
by Just_a_fan
godlameroso wrote: ↑30 Mar 2022, 12:42
Tommy Cookers wrote: ↑30 Mar 2022, 09:03
godlameroso wrote: ↑30 Mar 2022, 04:32
Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?
yet more of godl's nonsense !
half a degree of toe is roughly 5mm
toe is slip
with half a degree of slip the tyre will generate roughly 0.5 - 1 'g' worth of side-force - that's a lot of force
We are both wrong.
https://robrobinette.com/images/S2000/A ... anual4.jpg
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.
And if both tires have the same toe there is zero thrust steer.
If what I say is nonsense then how come I was right about the Mercedes car not being very good?
The 0.24 is not degrees, it's inches. 6mm is 0.24in. There are no degrees in that set up information.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 16:04
by Rodak
Five, toe settings generate more heat and wear than the camber settings you'd run sensibly ever does, by an order of magnitude
Yep. When I was racing FF2000 we had issues generating heat in the front tires. The solution was to change the toe. Worked a charm.....
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 16:33
by Fluido
Wheel toe in/out is setting for handling not aerodynamics...
I dont know you are kidding or what?
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 17:05
by godlameroso
Just_a_fan wrote: ↑30 Mar 2022, 13:38
godlameroso wrote: ↑30 Mar 2022, 12:42
Tommy Cookers wrote: ↑30 Mar 2022, 09:03
yet more of godl's nonsense !
half a degree of toe is roughly 5mm
toe is slip
with half a degree of slip the tyre will generate roughly 0.5 - 1 'g' worth of side-force - that's a lot of force
We are both wrong.
https://robrobinette.com/images/S2000/A ... anual4.jpg
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.
And if both tires have the same toe there is zero thrust steer.
If what I say is nonsense then how come I was right about the Mercedes car not being very good?
The 0.24 is not degrees, it's inches. 6mm is 0.24in. There are no degrees in that set up information.
degrees and inches are really close that you can call a quarter degree about a quarter inch. A 1 foot diameter circle has a 3.14 foot radius, 12x3.14 = 37.68 inches 360 degrees in a circle. Off by one golden ratio.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 17:08
by godlameroso
Fluido wrote: ↑30 Mar 2022, 16:33
Wheel toe in/out is setting for handling not aerodynamics...
I dont know you are kidding or what?
I'm serious.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 17:12
by PhillipM
godlameroso wrote: ↑30 Mar 2022, 17:05
degrees and inches are really close that you can call a quarter degree about a quarter inch. A 1 foot diameter circle has a 3.14 foot radius, 12x3.14 = 37.68 inches 360 degrees in a circle. Off by one golden ratio.
When was the last time you saw a wheel and tyre that was 1ft in circumference
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 17:13
by godlameroso
PhillipM wrote: ↑30 Mar 2022, 13:32
godlameroso wrote: ↑30 Mar 2022, 12:42
We are both wrong.
https://robrobinette.com/images/S2000/A ... anual4.jpg
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.
And if both tires have the same toe there is zero thrust steer.
If what I say is nonsense then how come I was right about the Mercedes car not being very good?
You do realise those numbers only apply for the S2000 with that specific wheel and tyre combo, right? You can't just nick the numbers out of your service manual and expect them to apply to every vehicle?
Any sort of performance car needing a full length diffuser is going to be on slicks that generate peak grip at a couple percent of slip, not the 8-10% of a road tyre.
So yes, adding half a degree to the rear tyres of toe out to generate tenths of a percent of aero loading extra is pretty insane.
Lol that's for a wheel tire combo that's a similar diameter to what F1 runs. Removing tire squirt from the equation is worth a lot, it doesn't suddenly stop mattering just because you don't like me. I don't like you and I can admit when you have a point.
Re: Suggestions for design undertray
Posted: 30 Mar 2022, 17:14
by godlameroso
PhillipM wrote: ↑30 Mar 2022, 17:12
godlameroso wrote: ↑30 Mar 2022, 17:05
degrees and inches are really close that you can call a quarter degree about a quarter inch. A 1 foot diameter circle has a 3.14 foot radius, 12x3.14 = 37.68 inches 360 degrees in a circle. Off by one golden ratio.
When was the last time you saw a wheel and tyre that was 1ft in circumference
it doesn't matter, the proportion is the same. 2/1 is the same if you have 16/8 or 512/256.