Contemplating a Build

[AlbertaSpeedShop]

After reading some of the forum though; will there be a class to enter in a couple years?

I'm about to graduate Automotive Engineering and made a few SAE cars in school. My father had a heart attack last year and its inspired us to work on a car together. For a few reasons something like an F1000 is our target. We're in Canada and F1000 doesn't exist here but Road Atlanta and COTA would be dream weekends and a goal to meet.

I've started a list of "This appears to be within the rules" ideas:

1:Variable Length Intake Runners (controlled by an Arduino if not stock to the motor)
2:What does this 1" from the reference area thing allow? 1" deep tunnels?
3:Can you start the diffuser tunnels early under the 1" thing for more expansion ratio and run less rear wing?
4:It appears you can do those late 80s front wing endplate scoops back to the front wheel centerline? Anything after that would have to be within the 1inchof the reference plane
5: Those fuel pick up papers i think Holley makes em. Is there something like that for Oil possibly making a super thin oil pan possible? (Fuel and oil are hydrocarbons so maybe that paper works for oil?)
6:Fly - By - Wire throttle. ... what extra stipulations does that require can be used for downshift throttle blips?
7:Fly - By - Wire clutch and Anti-Stall. Can't restart on the track but if you never stalled you can get going again.
8:Basalt is allowed in place of CF?
9:Basalt shrouds over control arms making them teardrop shaped and joining the driveshaft and rear LCA into one shape; also tie rod and UCA into one shape
10:Aero shrouding of uprights, brakes. Cover on outside too like from F1 2008 and 09
11:Capacitors in place of Batteries (since theres an Anti-Stall in place)
12: Flex joints for chassis side suspension joints
13: spar for diff structure, rear impact attenuation and rear wing mounts making engine removal quick and easy
14: Is an aluminum monocoque allowed?? I'm not sure what some of the wording is excluding. (9.1.1.2A seems weird to have CF, Kevlar, HONEYCOMB, Fiber Glass eliminating Aluminum monocoque i think) Where can aluminum honeycomb be sandwiched between sheetmetal?
15: i don't see chemical bonding anywhere. Can Side Impact panels be bonded between fasteners for instance?
16: are winglets allowed on uprights? 2G? 3F?
17: Hollow "Blown axles?" 3F?
18: Exhaust Blown Diffuser?
19: Does the car HAVE to be chain driven?
20: I can't see anything about location of fuel cell. Is that unregulated?
21: Does 8D rule out a zeroshift system?
22: is 9D saying wheels should be tethered? Is it talking about the brackets themselves should surround my flex joints? What does it even mean?
23: is Aero open? Is there a chord length or wing area thing in some appendix somewhere i dont see?
24: 9.1.1.10 Brakes are open .... so Adruino controlled brake proportioning valve? (making the most of weight distribution at the start)


Things I can do in Canada:
Hydraulically Interconnected Suspension (did a simple one as my engineering capstone)
Hydralic Inerter (Tungsten mineral oil and coiled tubing over a DAHC)

[ghickman]

After reading some of the forum though; will there be a class to enter in a couple years?

I'm about to graduate Automotive Engineering and made a few SAE cars in school. My father had a heart attack last year and its inspired us to work on a car together. For a few reasons something like an F1000 is our target. We're in Canada and F1000 doesn't exist here but Road Atlanta and COTA would be dream weekends and a goal to meet.

I've started a list of "This appears to be within the rules" ideas:

1:Variable Length Intake Runners (controlled by an Arduino if not stock to the motor)
2:What does this 1" from the reference area thing allow? 1" deep tunnels?
3:Can you start the diffuser tunnels early under the 1" thing for more expansion ratio and run less rear wing?
4:It appears you can do those late 80s front wing endplate scoops back to the front wheel centerline? Anything after that would have to be within the 1inchof the reference plane
5: Those fuel pick up papers i think Holley makes em. Is there something like that for Oil possibly making a super thin oil pan possible? (Fuel and oil are hydrocarbons so maybe that paper works for oil?)
6:Fly - By - Wire throttle. ... what extra stipulations does that require can be used for downshift throttle blips?
7:Fly - By - Wire clutch and Anti-Stall. Can't restart on the track but if you never stalled you can get going again.
8:Basalt is allowed in place of CF?
9:Basalt shrouds over control arms making them teardrop shaped and joining the driveshaft and rear LCA into one shape; also tie rod and UCA into one shape
10:Aero shrouding of uprights, brakes. Cover on outside too like from F1 2008 and 09
11:Capacitors in place of Batteries (since theres an Anti-Stall in place)
12: Flex joints for chassis side suspension joints
13: spar for diff structure, rear impact attenuation and rear wing mounts making engine removal quick and easy
14: Is an aluminum monocoque allowed?? I'm not sure what some of the wording is excluding. (9.1.1.2A seems weird to have CF, Kevlar, HONEYCOMB, Fiber Glass eliminating Aluminum monocoque i think) Where can aluminum honeycomb be sandwiched between sheetmetal?
15: i don't see chemical bonding anywhere. Can Side Impact panels be bonded between fasteners for instance?
16: are winglets allowed on uprights? 2G? 3F?
17: Hollow "Blown axles?" 3F?
18: Exhaust Blown Diffuser?
19: Does the car HAVE to be chain driven?
20: I can't see anything about location of fuel cell. Is that unregulated?
21: Does 8D rule out a zeroshift system?
22: is 9D saying wheels should be tethered? Is it talking about the brackets themselves should surround my flex joints? What does it even mean?
23: is Aero open? Is there a chord length or wing area thing in some appendix somewhere i dont see?
24: 9.1.1.10 Brakes are open .... so Adruino controlled brake proportioning valve? (making the most of weight distribution at the start)


Things I can do in Canada:
Hydraulically Interconnected Suspension (did a simple one as my engineering capstone)
Hydralic Inerter (Tungsten mineral oil and coiled tubing over a DAHC)

To answer your first line...of course there will be an F1000 class in 2 years. Don't let all this dooms day crap that a few on this forum are spewing out deter you. The CRB has their panties in a wad over the Gen4 Kawasaki because a few competitors got there asses hand to them...enough said.

1) Nope unless your engine somehow came with these.
2) Basically your tunnels leading up to the diffuser can not rise up more than 1" forward of the rear tire. I'm paraphrasing but that it.
3) You can start it clear up at the leading edge of the floor. Just can't exceed more than 1" rise ahead of the rear tire.
4) Yes as long as it meets the maximum width of front wing.
5) Not sure exactly what you are speaking of but if its what I think no that wouldn't be a good idea.
6) That's a good question. I don't see why not but why would you want to.
7) Again why would you want this? But likely legal.
8) Specifically where would you use this?
9) Technically no you aren't supposed to fair in your suspension arms.
10) YES....you likely didn't see my car at this years Runoffs. I had inner and outer wheel covers they were good for about 3mph and It allowed use to run more wing on the infield.
11) Wow, now you are really reaching out there. I suppose you could.
12) Not likely, the suspension has to be steel...unless your flex joints are steel?
13) If you could somehow make the case they are part of the rear impact structure you bet.
14) Nope...steel tube frame.
15) Nope can only be screwed or riveted at specific minimum intervals.
16) Good question, sort of a kin to Monkey Buckets? Maybe. I had something sort of like this on my car at the Runoffs this year. They came off right away, data didn't support having them on the car.
17) Yes
18) Yes but good luck making it work.
19) Good question
20) GCR pretty specific about this. See basic formula car construction
21) Not sure what zeroshift means
22) Wheels don't have to be tethered
23) As for wings as long as they meet the max width and height your good to go.
24) See GCR for this, it's pretty specific. Calipers are open.

Hydraulic inerter is now outlawed in SCCA.

[AlbertaSpeedShop]

Road Atlanta is a long drive to show up and be told ... well the rules don't say it but it's always been an understanding that you can't. Which I've read in a couple places in the rules forum now and it makes me .... nervous. Cause I'm totally "that guy" to explore grey areas.

1) I've got the rules infront of me and i don't see where they're banned. 4B engine components stock .... but in pictures and talk on here everyone seems to have made their own intakes and plenum. So am I not seeing in photos that it's just plain ordinary throttle bodies beneath the plenum? Though this new rule 5 makes variable intakes tricky in the future. What if they were stock to the bike? How would you meet the 4" requirement of Rule 5?

6) my big concern is the computer implemented throttle blips. "It's not driver initiated therefore it's not safe" and I gotta guess then that I should follow the wording I found in a tin top class somewhere about redundant sensors and springs

7) 6.11.6 makes it seem at first blush like you're not allowed to use the starter to get the engine restarted while on track. So if you don't stall you're fine to restart. Plus protection against back rolling. Plus launch control sorta by using that 2 position clutch lever thing in F1

8) it's supposed to be stronger than e-glass but cheaper than CFRP so i was kinda thinking of use it nearly everywhere. Sollar Composites has it on their site but with a CF tow and Basalt Warp. I'm sure since they have that you could ask for a roll of Basalt in both warp and tow though

9) Where now is this banned? 2G ... you can streamline your UCA/LCA. Doesn't seem like a huge stretch to make that a hollow shroud extending forward to cover the Tie Rod so the air isn't seeing the gap between the two arms. There's more benefit shrouding the rotating half shaft next to a possible placement of the rear leg of LCA. I remember reading about an F1 team doing that recently. I've got a genetic algorithm working out suspension locations and it seems like I could work that into my fitness function.

14) does "Stabilized Material" refer to a honeycomb sandwiched construction?

15) they should really say where you can and can't chemical bond

16) Really?? I threw this in here as a free bee to get conversation started cause it's definitely not allowed under 2G. Properly executed they ARE a spoiler and are not symmetric. The Upright IS a suspension member (asked anyway incase suspension member is just UCA LCA but even the chassis is a suspension member i would think since doing 4 link analysis it's one of your links). So did you do symmetric shapes with an angle of attack? Or plain flat symmetric shapes just to laminarize the airflow off the back of the tires and clean up some of that turbulance?

20) this whole double firewall thing. Protecting the tank against headers i suppose is why ... we had something a little more open on our SAE cars that it was easier to work on the car from underneath. Canadian rules say the tank must be 6" above ground unless within the chassis structure which I'll meet. Just not wanting that second firewall

21) check it out. Articles rave about it. But I would have to think its considered preselection. Maybe you'd recognize it better if I called it Flat-shift company calls it Zeroshift though

22) so what does 9D mean? The ETS Formula SAE team would put the spherical bearing on the chassis instead and were able to make a very stiff lightweight suspension joint doing that. But it sounds like 9D eliminates this idea talking about "a box around the joint" if I went flex joint instead does that mean i still have to put square tube over that? Really in a crash or hard curb strike LCA/UCA is gonna move inches not the millimeters that a sqtb shroud would protect from

24) i guess i don't understand the minutiae of "restricted class" and Brakes "unrestricted except" since there'snothing in there about mechatronic controls and they unrestricted brakes ... it sounded fair game


Sucks about inerters. Dead simple to make, adjust by different fluid concentrations of Tungsten mineral oil (since mercury is kinda bad i suppose) excellent for curb strikes like these cars see on a regular basis. One could say the same about H.I.S. simple to simulate, simple to build, suspension adjustments as simple as an air pump. But with more rules banning it there's nothing in it for a company to produce em.


Thank you so much for you contributions to our project. Dad doesn't have the patience for rules and just wants to build. However the rules are your build instructions so understanding w the limits of the rules is most important step number 1 and last and everything in between.

[S Lathrop]

Over the years I have had the pleasure of spending some time with engineering students working on FSAE projects. One of the best was with a group who had their project at a race at 3 Rivers, Quebec. Those kids had solved the fundamental problem of monoshock suspension systems. Funny thing was they had no idea they had done that.

In general, and your list demonstrates that, they tend to get carried away with all the new fangled ideas and fail to grasp the very basics of what they have to do to make a good race car. The most fundamental problem you have in the design of a car is getting the tires to stick to the track, called mechanical grip. Equally challenging is to have a car that is easy to drive and instills confidence in the driver that he can drive right at the limit of adhesion and nothing bad will happen. The only way I know to get that knowledge is to drive a car yourself.

All the wizzy bits are there to solve a particular problem that the designers encountered as they developed their cars. Building a car just to incorporate the newest design trends is a sure prescription to failure or at a minimum, a very long development period.

When you read the SCCA GCR for FB rules, you should read the rules for FF and FC as well. FB rules are largely derived from the practices established in those other classes. So when similar wording is used, the FF/FC rules will be the standard.

Designing and building a car is great fun if you do it well. Starting with FB is very much like learning to fly a Pitts competition aerobatic air plane.

[Mike Devins]

16: are winglets allowed on uprights? 2G? 3F?

I would guess that they would be interpreted as movable aero

[AlbertaSpeedShop]

Thanks for your responses.

I'm thinking that was the ETS team you met at Trois Rivière. In pics of their latest car with the billet crank case there's only a poor one from 5 feet back of something else but the bellcranks weren't what i was expecting. Seemed like one shock connecting left and right sides in bump. And another springing/damping roll exclusively. Maybe not a horrible idea for this class. I saw on here chassis torsional stiffness goals of 10000 in lbf. Or maybe they meant ft lbf. Lets say 2 inch between roll centers and a spring rate of 2.5 Hz or 190lbf/in that's 380in-lbf Torsion through the frame and 10times that 3800 in lbf minimum torsion target. You all have the benefit of experience though ... I'm thinking shoot for the middle at 5000 in-lbf. The chassis pics I've seen appear quite heavy. I haven't coded it yet but my idea was to run a Genetic algorithm through Frame 3DD. Try and free up some ballast weight to put on the ground

In general my list shows that I might suffer ADD and have a lot buzzing around in there. But yeah I'll agree that the best way to learn is do. I did that in school but I was doing it all and not doing school so i had to quit. I was cheating my teammates of the same by doing it all for them.

Now i hope to do another wizzy bit to learn about it. Aero alone is that wizzy bit that brought me here i guess. Though honestly I thought it was actually rules restricted and that's why the aero was slight. Now i see it's because small car, small car power, big cars tracks so drag is the big factor. I think these would be more fun to design to something like a driver development track promoting a downforce development race instead of the L/D development race this became. The shrouding of half shafts and tie rods sound like something simple to learn about by trying.

The mechatronic stuff ... I've always been a half decent coder and it'd be neat to see what could be acheived that route

[ghickman]

Designing and building a car is great fun if you do it well. Starting with FB is very much like learning to fly a Pitts competition aerobatic air plane.

Not so bad if its a 2 seat pitts and you've got an instructor with you and you're already an accomplished tail dragger pilot. Awesome analogy for the pilots among us.

Steve-
If you are ever in San Diego give me a call. I'll take you up in the most badass aerobatic biplane ever built.

[Wren]

I always like a good rules discussion and I used to be involved in the class. I'll take a shot at it.

1. Only if the engine originally came with it. I can't imagine how you would make it work with the stock engine and throttle bodies. Yes, people run stock throttle bodies under their air boxes.

2. It allows you to have a 1" variance in the floor of the car above the reference area and in front of the leading edge of the rear tire. If you want to use it for tunnels, you can. You wouldn't be the first person.

3. You can start your diffuser forward of the leading edge of the rear tire by using the 1" rule. I believe this is quite common.

4. Sure

5. How much thinner are you going to get than a good dry sump oil pan? An oil system needs to move a lot more volume than a fuel pickup.

6. I really, really don't want to share the track with someone who decided to home build their own fly by wire throttle. This seems like the kind of thing that could waste months of development and end up with something that is way less reliable and heavier than a push-pull cable to the stock throttle bodies. If you want to blip the throttle, use a solenoid like everyone else. The rules don't seem to specifically address it, but the P1 rules do. See what they say.

Shifter initiated throttle blips have been in the class since at least 2010.

7. Again, why? You could probably get away with it under the rules, but you are going to spend a lot of time and money to have something that is less reliable and heavier than a hydraulic set up.

8. Probably, but the use of CF is pretty restricted. The class rules are meant to prevent structural composites in anything but a crush structure.

9. No, it would be bodywork. Make sure that you read the technical glossary as well. Those are rules too. Just use the aero tube that everyone else uses.

I wonder if the SCCA should consider relooking at this rule. Having plastic shrouds in a few sizes would be very cheap to have manufactured and could save some time, hassle, and expense on suspension fabrication by using round tube. But, that's a discussion for another time.

10. Your uprights and brakes should be contained inside the wheel. I've always wondered how wheel fairings are legal. They are licked by the airstream and above the floor. They should be subject to the maximum width as well as the requirement to be firmly fixed to the chassis. I've seen them on cars, but I've never thought they were legal.

11. Probably, but you can buy really good lightweight batteries in the $500 range. It seems like a lot of work for no reward.

12. They would have to be steel.

13. Yes. This is common. The rear spar may be considered to be a bracket.

14. Definitely not. This is a class for tube frame cars.

15. Definitely not. 9.1.1.G.2.a is pretty clear that you may not have stress bearing panels and that any attachment method (including bonding) is not ok except for where specifically allowed and it does not allow it for the side impact panels.

16. No, moveable aero. Also, your uprights should be hidden inside your wheels.

17. I think so, but good luck making it work. As a side note, I have always liked it when people tried to incorporate more ideas from F1 into their low horsepower, lightweight SCCA formula car. It pretty much guarantees that they are lost.

18. Yes, but good luck making it work without throttle overrun. see note above

19. I don't see any restrictions on orientation of the engine or required final drive method. If you get serious about it, you might want to go down the new path for verifying compliance before you build it.

20. Reference the general formula car construction rules. This isn't the area to get cute. Do the safe thing. You should not be able to access your fuel cell from underneath the car without major surgery on the car.

21. I did a quick google search and if I understand it correctly, you would have to swap parts around inside the transmission, which would make it illegal. You could try a flat shifter, but I have seen nothing but problems from them. Look at the geartronics air shifter. It is a little pricey, but it works very, very well.

22. It's easier explained in a picture and I don't have any on me, but you basically have a steel box surrounding the suspension pick up. It is to contain the end of the suspension arm from penetrating further into the chassis and poking a hole in the driver during a crash.

23. You can do whatever you want that fits inside the dimensions given in the rules.

24. Huh? you want to electronically control the brake proportioning? Why can't you just use a balance bar. start of what?

As Gary already pointed out. The SCCA bans inerters. Yes, you could maybe make your own, but most of the field would just go out and spend $60k+ on the good stuff.

Now to be all negative:

I've been down this road with a friend. It is really, really, really hard. It will take years of your life and much, much more money than just buying an existing car and working on it or developing it. When we went down this road it turned out that step one was to buy a machine shop. Look at every little part on a race car and realize that someone had to make that and if you are the manufacturer...congratulations, you get to make it.

Now for the positive:

I've been down this road with a friend. It is really, really, really fun. In my office I don't have a picture of my girlfriend or my dog, but I do have pictures from the 2010 runoffs and sample parts that we have made. I can't imagine what would be more rewarding.

Don't let my negativity scare you off. If you are young and want to be an engineer, this really will have a positive impact on your career. If you can walk into an interview and talk about how you have used your education to do something besides pass tests, you will stand head and shoulders above the other applicants.

You may want to look into FS if all that you want to do is experiment. The down side is that you don't get the opportunity to compare your efforts to others on a level playing field.

Starting with FB is very much like learning to fly a Pitts competition aerobatic air plane.

I did primary instruction in a taildragger(but it was a Pacer, not a Pitts) and I still wouldn't consider driving an FB.

Great analogy.

[ghickman]

I did primary instruction in a taildragger(but it was a Pacer, not a Pitts) and I still wouldn't consider driving an FB.

Great analogy.

Chicken!

[AlbertaSpeedShop]

So what's the worst part of driving an FB that it inspires these aerobatic plane analogies? The power to weight maybr means it might be a challenge to put the power down and throttle control is very important.

The wheel to wheel with open wheels parts might leave some brown streaks behind on the seat. So like my limited karting experience be ginger at the start and make clean passes. Very easy to say, very easy to get in over your head without proper respect. I'll need to do more karting to get comfortable with that.

Is it the physicality of the cars pulling 2G hard on a neck ... again karting and neck strengthening.

[JerryH]

So what's the worst part of driving an FB that it inspires these aerobatic plane analogies? The power to weight maybr means it might be a challenge to put the power down and throttle control is very important.

The wheel to wheel with open wheels parts might leave some brown streaks behind on the seat. So like my limited karting experience be ginger at the start and make clean passes. Very easy to say, very easy to get in over your head without proper respect. I'll need to do more karting to get comfortable with that.

Is it the physicality of the cars pulling 2G hard on a neck ... again karting and neck strengthening.

Everything happens very quickly.......and we see 3g in some corners....and near that braking.

They are a rush to drive. Part of it is the sound of the engine.

Got my tail dragger start in a Luscombe 8E. very short couple with heel brakes. very prone to ground looping. Not nearly as exciting as an FB!

Jerry Hodges
JDR Race Cars

[S Lathrop]

Not so bad if its a 2 seat pitts and you've got an instructor with you and you're already an accomplished tail dragger pilot. Awesome analogy for the pilots among us.

Steve-
If you are ever in San Diego give me a call. I'll take you up in the most badass aerobatic biplane ever built.

I am a pilot and I do fly tail draggers (C180, and J3). But a Pitta is way beyond my skill set. I quit racing when it came time to send the first of my 5 kids to college. I started flying when the last 2 of my kids were finishing college and starting their flying careers.

I am not wrong about the Pitts analogy, am I ?

[ghickman]

I am a pilot and I do fly tail draggers (C180, and J3). But a Pitta is way beyond my skill set. I quit racing when it came time to send the first of my 5 kids to college. I started flying when the last 2 of my kids were finishing college and starting their flying careers.

I am not wrong about the Pitts analogy, am I ?

No you're right on there about the Pitts.

Real pilots fly tail draggers....I own a 1979 Cessna 180. Anyone that can handle a 180 on the ground can fly anything. They have a reputation of being a ground loop waiting to happen. You just have to stay on top of them, kinda like driving a race car.

My respect for you has been further elevated. Good on you for getting your kids through college also.

I come from a family of pilots. My brother was a triple centurion in an A7 corsair in viet nam and my dad was a B17 pilot in WWII. He's 90 now and stopped flying 5 years ago when his vision went to crap.

[S Lathrop]

Gary;

When I was a kid, the family transport was a Bamboo Bomber, Cessna Bob Cat. My mother was a qualified pilot in that plane. My youngest son finished up test pilot school at Pawtucket Naval Air Station a year ago And my daughter is a pilot flying emergency medical helicopters. None of my kids race cars.

[Jphoenix]

...the most badass aerobatic biplane ever built.

A Showcat or a Pitts M12?

I got a ride in a Bucker Jungmann many years ago - that was exhilirating!

[S Lathrop]

AlbertaSpeedShop;

Get some track time in an entry level car while you are designing and building your car.

I think FV is absolutely the best place to start. That is mainly because things happen so slowly and you can really explore what goes on at the limit of adhesion. You learn to drive a FV well and the FB will be relatively easy to come to grips with. If you start in a faster car, you will spend more time trying not to kill yourself and damage your car, instead of learning the skills you need to be really fast.

When I was driving, I would frequently get into a FV to practice or study some detail of my driving I wanted to improve. The cost of making a mistake in a faster car was just potentially too expensive.

[ghickman]

A Showcat or a Pitts M12?

I got a ride in a Bucker Jungmann many years ago - that was exhilirating!

Bucker Jungmann with a Lycoming, it's a Czech built Jungmann which is the desirable one. It has been highly midified for aerobatics. Has a long history. My father flew it in aerobatic competitions clear into the early 70's before it became obsolete in comp by the Pitts then later all the monoplanes. It'll do snap rolls that'll make your eyes pop out.

Also have a Swiss Jungmeister with a Siemens radial engine. It's original all the way down to the German Luftwaffe symbols on the bolt heads. It somehow was smuggled out of Germany in late 1939 and was given to the Swiss Army which at the time was a neutral country. My dad imported it from Switzerland in the 60's when they unloaded them, they want them back now. It's super rare.

[Jphoenix]

Yes, that Jungmann I rode in did snap rolls that popped my eyes out! What a machine - truly a point and shoot aircraft.

Jungmeister - cool as well, very classic, but never got a ride in one. I believe my all time favorite is the Edge 540, just for purely personal reasons - but we digress

[ghickman]

Yes, that Jungmann I rode in did snap rolls that popped my eyes out! What a machine - truly a point and shoot aircraft.

Jungmeister - cool as well, very classic, but never got a ride in one. I believe my all time favorite is the Edge 540, just for purely personal reasons - but we digress

Jungmeister is the single seater.

The amazing thing about the Buckers was that all the control surfaces are suspended on ball bearings. You almost cant feel the controls.

When I retire from car racing, which could be 2016...I'm going to buy an Edge 540 and try and compete in the Red Bull Air Races. My family thinks I'm nuts.

You can tell I like talking airplanes...sorry for the thread detour.

[Jnovak]

Pay very close attention to everything Wren said. He and his friend build one of the very best FB cars ever and their many great results were not an accident.

My moto is "The lightest part on a race cars is the one that is not there"

[Jphoenix]

I'm going to buy an Edge 540.

I still have my Edge 540 hat from the factory (in Oklahoma) I visited in 2004. I've inspected a lot of airshow aircraft in my day job and I find the Edge to be a quality machine. In the hands of a guy like Kirby Chambliss - it's pure art.

OK, I promise to stop now

[AlbertaSpeedShop]

I don't know that I'm starting at FB. I've got limited time in TAG 2-stroke Karts but I learned a bit there. I've got a lot of time in Autocross as locally that's a community 100 strong, and stronger than circuit racing. My plan with this car is to Autocross it first, go after a National Title with the car. And then take off the Autocross legal stuff and go to FB with it. I feel like we'd know the car well and the reactivity of the car... Our driver Orrin holds the street tires lap record of the closest circuit. The FB car would do 220km/h on the straights there but it's still just a time attack. Wheel to wheel is the next variable. I think maybe you're all suggesting the avoiding other cars under braking into that first turn is where everything happens very quick.

This build will be a couple years. I'll be Boilermaking for a couple years building and purchasing and building a purchasing again. And then the autocross goals to develop the car and learn set ups. and then an FB circuit

5) In pictures the oil pans appear to be 1.5" tall. looks about an inch too tall. And the motor is the single heaviest piece. lower is better. Is there a handling deficiency in these Kawasaki Gen 4 motors? Kawasaki does like to put the clutch and gear cassette high, very high compared to others. That's why I avoid them at first blush. But I guess with 1000lbs to play with, the effect from a single 150lb motor is smaller than SAE.

6) There's a company in england sells the full throttle body setup. would probably take that and make it work in stock throttle bodies .... or reverse engineer it and then sell it on ebay. or I may just not do FBY Throttles at all. Just exploring the possiblities. I hadn't considered a solenoid ... doesn't seem as controlled as a servo but I guess speed is the chief concern to match the low shifting times of a pneumatic ram.

7) With just a hydraulic system would you be able to disengage the clutch with just your finger tips behind the steering wheel? I haven't seen many motorcycle clutch levers in the cockpits of any youtube videos. What is the common thing to do with clutches? does everyone 3rd pedal it?

8) But if you can shave a layer in bodywork because of a stiffer material. it's probably in the neighborhood of 10lbs on these cars?

9) So the rule really should read that you can use Aero shaped steel tubing, but you can't add streamlining to round tube?

10) I suppose their shadowed by the tire for the 1" rule, and they're a bracket on a bracket which IS firmly attached to the chassis, ergo this bracket is also firmly attached to the chassis?? Does sound like you raise an excellent point about the chassis attachment nature of bodywork. would they be allowed if they had a brake cooling duct built in?? now suddenly it has a more legitimate purpose for being there especially since as a formula class theres no fender there to plumb brake air through.

11)I'd have to find the youtube again and there'd be testing it out on a full size car for myself but the caps were like $15 and weigh grams. Though batteries are typically mounted very low down anyway so it's not a big difference ballast weight vs battery weight. would more just be an autocross thing where there's no min weight

12) Aluminum fatigues anyway so steel it is

16) Does it fail 3F?? It doesn't move in it's own Upright coordinate system. If my point 17 the blown axle passes 3f? F1 has the moveable aero device rules, their designers also make EXTENSIVE use of these on the rear uprights now that they lost their rear beam wing. I'll concede they fail 2G though .... and It would be tricky to pass the 1" bodywork rule on the rear wheels too since the floor has a gap to clear the rear tire. I'd be interested to see how much or if at all they clean up the wake behind the rear tires though. Add that to the CFD work load to come.

17) They're to fill in the wake behind the front tire, reduce drag .... from the conversations I read here it seems they'd fit right in? You'd have to do some CFD as to how big of a hole to punch in the axle but it would basically seem as big as you can design it to fit

18) With FBY Throttle overrun is possible. Now, the guys in F1 spent millions on these for small gains so I'm sure I'll not do it .... but an exhaust blown monkey seat maybe. Probably not an even noticeable amount of Lift though so it'd be an "I've got the exhaust plumbed there anyway, and pull rods so I need the heat off the dampers"

19) I'll likely not build suspension so narrow I need it. It could coke bottle the car pretty good though. If I get decent at casting it's just as easy to cast a diff oil housing as it is to cast a transaxle style diff housing. Probably not seriously going to happen. Whats got more power loss, chain whip and friction, or a spiral bevel gear?

24) Your balance bar is set to say 70-30 or 80-20. It's set there cause your weight distribution is going to eventually move there once the chassis dives. But when you start braking, your weight distribution is 50-50 or 40-60, and you have the potential to do more braking earlier if your able to dynamically adjust brake proportioning to match. I learned in a Vehicle dynamics class that it's been tried .... it's an idea, but in practical application just seems like a way to over burden a servo and be left at the mercy of the setting where it let out the blue smoke


Finally, I'm not scared of the amount of work, I've been through it 4 times already. The machining bill scares me. Gotta do as much lathe work ourselves as possible and reduce all the mill work we can. We're both accomplished welders and Steel uprights/bellcranks/suspension members are the planned way forward. Laser-cutting is cheap. Yes there are lots of parts to be made, that just means it takes time. what's realistically achievable is 3.5 - 5 yrs until turning a wheel. we could do 6 months rolling chassis once those key parts are purchased and decisions made. It's the other fiddly bits that take a lot of time. I've never done an electrical system but I have people I can ask ... but it's stock anyway so I shouldn't need to change much

FS .... I think that's the idea I started from. For $450 I bought a vacuum pump for harvesting maple tree sap, cause it pulls a lot of very hard vacuum 8CFM at very nearly 28inHg for a week non-stop. Great for VARTM I thought and making a monocoque. Now looks like it'll just be used for VARTM bodywork

Jnovak ... you're all getting through. I have some arrogance which I'm sure is rampant in auto racing. but I try to fact check everything I'm told to understand better where that person is speaking from. I don't flat out ignore advice ..... until it's the second or third time I'm being told a supercharger pumps the air through the middle, and so do Oil Gear Pumps .... stuff like that I stop listening. But suggesting FS is not far off since if I look at what I wanted to do vs what class that fits in, FS is right there. But if I'm to get dad involved and reduce costs, FB is where it's at! We started at a Rusto-Mod idea but don't have the tools 2 post lifts and such to do a full size car. Dad would put them in for a Chevelle but that's like a 10yr project with the waiting to get those tools first. So building an FB off a jig table, thats something that can get started right away, and I get to engineer the tits off of. Using all the computer tools I had in the pipeline when I had to walk away from SAE

[RSS]

I don't know that I'm starting at FB. I've got limited time in TAG 2-stroke Karts but I learned a bit there. I've got a lot of time in Autocross as locally that's a community 100 strong, and stronger than circuit racing. My plan with this car is to Autocross it first, go after a National Title with the car. And then take off the Autocross legal stuff and go to FB with it. I feel like we'd know the car well and the reactivity of the car... Our driver Orrin holds the street tires lap record of the closest circuit. The FB car would do 220km/h on the straights there but it's still just a time attack. Wheel to wheel is the next variable. I think maybe you're all suggesting the avoiding other cars under braking into that first turn is where everything happens very quick.

No it wont try probably 20kph+ slower

[AlbertaSpeedShop]

Roger good to see Yeah here
Castrol is no Mosport or Road Atlanta. Maybe you're right 180-200 is more realistic. I have a drawing of Castrol with corner radiuses but no straight lengths (double checking ... nope just corners and banking maybe some confusing 2+700 type numbers)

Let's hope Badlands happens. Website says FIA Spec 2 course. Which means every league of car but F1. So we probably won't get WEC but it's Alberta we weren't getting WEC anyway. But Maybe Alberta gets an Indy race back or ALMS. Badlands is gonna be amazing for Alberta racing

[S Lathrop]

AlbertaSpeedShop

You mentioned not having a mill. I am going to suggest that you get a mill before you even think about starting to build a car, especially of your own design. In a car build, there are way more mill hours spent making parts than any thing else. I would suggest that you get a CNC mill. You will spend the price of a good mill having someone else do the work.

I have a 70's vintage Bridgeport Series 1 CNC mill. This is similar to a standard Bridgeport knee mill but it is CNC controlled only. You can buy a mill like mine for $1000 or so because almost none of them work. The computers and controls have died.

Mills like mine do not have manual controls so when the computers go out they are useless. I bought a MachhMotion control system, machmotion.com. I was able to use all the motors from the Bridgeport machine so I spent a lot less than what they are advertising now. The Mach3 control software allows me to do 3 axis surface milling. Something that the machine could not do when it was new. I did my conversion for just over $3000. With your education, you should be able to build a control system for way less than I spent. To buy a new 3 axis mill that is as rigid as my old Bridgeport will cost you $25,000 to $35,000. The down side of my machine is that it is slow.

Just as a reference, a FB at the Daytona run offs had a trap speed of 272 kph. 240 is a very common speed to see.

[stephen wilson]

We started at a Rusto-Mod idea but don't have the tools 2 post lifts and such to do a full size car. Dad would put them in for a Chevelle but that's like a 10yr project with the waiting to get those tools first. So building an FB off a jig table, thats something that can get started right away

This comment has me confused. You don't have the tools to do a Restomod, but you feel building a FB from scratch is easier?

[ghickman]

This comment has me confused. You don't have the tools to do a Restomod, but you feel building a FB from scratch is easier?

I believe what he's saying here is he doesn't have a 2 post car lift. I've personally restored around 30 British cars without a car lift and kinda looked at having a lift as being a luxury.

The restomod on the Chevelle sounds like fun.

Hey he's a FSAE grad so he has this in his dna. Have at it and hope we see you on the track.

[stephen wilson]

I get the lift part, but calling it a "10 Year project waiting to get those tools" has me wondering how they're going to afford building a FB. BTW, not to be insult the OP, but it appears he didn't complete the FSAE program.

And yeah, I'm doing a '65 mustang without a lift or rotisserie, so it's certainly not required.

[AlbertaSpeedShop]

I go back to school for my last course, Quality Control. And then I'm done engineering.

SAE wasn't a course at my school, an extra curricular. However like happens to a lot of students I missed the point of school when I was learning so much from SAE. As can happen in big group projects though, my teammates would sit back and watch me work ... or it sure feels that way at times. If it was on the car and it required welding, I designed it and made it.

So I didn't learn as much about powertrain as I would have liked.

go on Copart.com and get a crashed Gixxer is ... $2 - 5000

If we were to build a Rusto-mod (rat rod made from modern materials) we'd wanna get creative with a motor, rat rods are all about the motor. Was most favoring a BMW M5 motor from a crashed car .... $10K so right there FB is half the price on one component

Rusto-mod has a lot more surface area so a lot more CF materials.

If we did a Chevelle it would be Resto-Mod or Street fighter style. again motor more expensive, body work much more expensive. there's parts on those for luxuries that aren't in an FB radios, heaters, AC, speakers and the kick panels and bumpers and everything. There's just more of everything and its more money because of that. We wouldn't be half assing it. If we went production car route it would be a show winner. much more time and money.

FB ... it needs to look decent, but some waves in the bodywork aren't the end of the world. so it's a good place to build better fairing skills. The engineering is where the mechanical grip and weight and speed is at. Dad's a farm boy, if I don't give him drawings he'll try and make a brake box out of 2x1 Flat bar. It'll test and grow our relationship which is my ultimate goal in the end. I wanna make memories with the old man.

my budget for FB is in the $50K neighborhood. My budget for a Chevelle $200K, so thats the difference 10 yrs vs 3.5-5yrs. however, alberta's economy is in the ****ters and Notley doesn't give a crap, she want's environmentalism over jobs so ... the doomsdayer in me says maybe perhaps this is a no go. But I've finally got the right rules after looking in 6 wrong places and I can at least put ideas to the page that can be dusted off later if I can't find job security when I come back from school

an hour from us dad has a hobby farm. he has a barn/shop for the tractors and baler and things. It has no concrete floor. Just dirt. before a 2 post goes in it needs a floor. $20k he figures for the floor. An FB can be built on a jig table which can be levelled up in the dirt. have it drawn up for laser cutting. quote is $800 for the laser cutting and material. By lasercutting the crossmembers I know the surface is flat. in the surface I've got 5/8" holes on a grid .... It's basically a Build Pro table and can use all the same tools they have for their table. But I can also lasercut the various jigs that'll bolt into the table for suspension points and clamps for cross member tubes. Via lasercutting things get super cheap and for the accuracy. however it's hard to fit a full size car on a small weld table ... that becomes a very large weld table. I think you get the point. smaller is cheaper. race car doesn't add anything unnecessary therefore cheaper. It's a stock motor class therefore cheaper. I can very nearly get an FB to be road legal ... therefor attract sponsors as it's driving advertising. and theres a weekly car meeting in Red Deer that's on average 500 cars strong. Great place for sponsors to be seen by wives and kids as well not just fellow car guys on a car that will almost always have a crowd around it because it's a formula car on the road and different from all the cameros and chevelles and mustangs in attendance

I get comments enough it has my attention, that I over complicate matters like a true engineer. That a rat rod is the cheapest car possible to make and that shouldn't deter me and such things. yeah, there's some truth in that. But I wouldn't be as proud of a car we just pieced together from the crap heap out back as of a car we designed and built from scratch. Thats what I went to school for, a scratch build is putting my education to use, a crap heap build is taking what compromises are handed to me and swallowing them

Past SAE teammates say to me "I wanna build a car too! I'm gonna start with Mazda Miata uprights" So you're stuck with a LCA 3" off the ground, how do you build a diffuser around that? Miata uprights were for a McPherson strut, you wanna build a formula car, you gotta take something that was meant for a strut and put the UCA where they put the strut ... it's close to where you'd have the upper ball joint anyway but it wasn't meant for that. I'm a scratch build guy, things are where you planned them to be not where you were forced to put them


Thank you Steve Lathrop about the cheap CNC mill. There's all sorts of 80/20 Gantry mill ideas on the internets but gantries just aren't as robust as the old Bridgeports. We did a vast majority of our SAE car on a manual Bridgeport. pretty much just had the hubs done on a TrakMill as I remember .... lots and lots done on a simple old manual Bridgeport. Hoped to find something like that on Kijiji or ebay or auctions.

[Wren]

Remember that in general autocross is a different design problem than road racing.

5. We made our pans out of 1.5" plate, but there are things inside of that. If you are dry sumped, you have a pump, pickups, and supply in there. Wet sump needs somewhere to put the oil and baffles.

6. If you use the geartronics, they include the pneumatic ram for blipping as part of the package.

7. You are going to use the clutch for leaving the grid, coming in to the pits, and when you spin. I have seen some people talk about putting the clutch on the steering wheel, but I've never seen a solution that seems acceptable. You want something that will be easy to find when you need to put both feet in.

You are definitely allowed to use the starter to restart the engine on the track. 6.11.6 is referencing holding down the starter to move the car (think Dan Gurney at Daytona in 1962).

8. Yes, but it may not be worth it if there is a lot of extra expense. If you want to get serious about getting weight out of the bodywork, pre-preg cloth in an autoclave is the only way to go. Remember that you still have to have your Kevlar in the body sides.

9. It doesn't need to be that specific, but that is an accurate assessment of the rule. You may want to consider the squished down tube as it is cheaper. There have been a few threads on here about it.

10. Check the frame definition in the glossary. Something out on the upright is never going to be bodywork. I'm not sure what would change if you added a brake duct. Realistically, you won't need brake ducts on the car.

12. Flex joints instead of sphericals/rod ends is going to be a miniscule difference that you will need a really stiff car, high dollar shocks, and a great data system to have a chance of noticing. This will not be low hanging fruit and the risk reward isn't there. You really don't want to turn in to T1 at Mosport and find out that you missed on your calculations a little bit. What are you hoping to gain from them?

16. Maybe I don't understand what you are talking about. Have a picture?

17. Seems like a lot of work little reward. CFD in the area of the tire, rear upright, wheel, rear suspension is going to be a non-trivial problem. Lot of spinning things in there. Since the primary function of the axle is going to be mounting the wheel, I am sure that no one is going to hassle you about it.

18. I think that you would have a shot at making some real down force if you could make use of the exhaust, but it's going to take a whole lot more than just holding the throttle open.

24. You are on the brakes a fraction of the lap and the braking zones are incredibly short in these cars. It's not going to be worth it.

Finally, I'm not scared of the amount of work, I've been through it 4 times already. The machining bill scares me. Gotta do as much lathe work ourselves as possible and reduce all the mill work we can. We're both accomplished welders and Steel uprights/bellcranks/suspension members are the planned way forward. Laser-cutting is cheap. Yes there are lots of parts to be made, that just means it takes time.

I did FSAE before I got involved in SCCA so don't take this the wrong way, but the amount of work and what is required is very different for building your own FB vs. building an FSAE car.

Fabricated steel uprights and bell cranks will work perfectly well. They have worked well on cars at some very high levels. Designing and building your own car is going to require a mill, lathe, and TIG welder at a minimum. When we got serious it took Brandon buying a new vertical machining center and me buying a new CNC lathe (I had never used one before I bought it). This turned out to be the easiest/cheapest way to do it.

Paying others and waiting on them will hurt you on cost and performance. There will also be some discouraging times when you realize that you failed to consider some second or third order effect of the part you just finished. On a few occasions I have had the pleasure of taking a stack of new parts and dumping them straight into the trash can. It's not fun.

So I didn't learn as much about powertrain as I would have liked.

The nice thing is that FB is not going to require you to know a lot about powertrain. Even getting the engine to run in the chassis will already be well understood.

go on Copart.com and get a crashed Gixxer is ... $2 - 5000

If we were to build a Rusto-mod (rat rod made from modern materials) we'd wanna get creative with a motor, rat rods are all about the motor. Was most favoring a BMW M5 motor from a crashed car .... $10K so right there FB is half the price on one component

Rusto-mod has a lot more surface area so a lot more CF materials.

If we did a Chevelle it would be Resto-Mod or Street fighter style. again motor more expensive, body work much more expensive. there's parts on those for luxuries that aren't in an FB radios, heaters, AC, speakers and the kick panels and bumpers and everything. There's just more of everything and its more money because of that. We wouldn't be half assing it. If we went production car route it would be a show winner. much more time and money.

FB ... it needs to look decent, but some waves in the bodywork aren't the end of the world. so it's a good place to build better fairing skills. The engineering is where the mechanical grip and weight and speed is at. Dad's a farm boy, if I don't give him drawings he'll try and make a brake box out of 2x1 Flat bar. It'll test and grow our relationship which is my ultimate goal in the end. I wanna make memories with the old man.

my budget for FB is in the $50K neighborhood. My budget for a Chevelle $200K, so thats the difference 10 yrs vs 3.5-5yrs. however, alberta's economy is in the ****ters and Notley doesn't give a crap, she want's environmentalism over jobs so ... the doomsdayer in me says maybe perhaps this is a no go. But I've finally got the right rules after looking in 6 wrong places and I can at least put ideas to the page that can be dusted off later if I can't find job security when I come back from school

Please be realistic about how much building a car from scratch is going to cost you. From experience, I think that it will be hard to accomplish for $50k. When you look at a car, realize that you are going to have to pay for every bolt and plumbing piece on that car and your bill will get discouragingly large very, very quickly. In general, you are going to end up using much nicer parts on an FB. Look at the expense of some of the braking components in use on FB cars just for an example. It is always cheaper to buy a used car instead of building a new one.

Remember, that $2k-5k GSXR engine is going to need to be replaced or have an expensive rebuild every 1,500 miles. Sometimes they will blow up for no good reason at all. To be competitive, you are going to buy a set of tires every weekend. You are going to have to replace the chain every 4 weekends or so(~$100 every time). This isn't a cheap class. It is a reasonably economic class for how fast you can go.

I can very nearly get an FB to be road legal ... therefor attract sponsors as it's driving advertising. and theres a weekly car meeting in Red Deer that's on average 500 cars strong. Great place for sponsors to be seen by wives and kids as well not just fellow car guys on a car that will almost always have a crowd around it because it's a formula car on the road and different from all the cameros and chevelles and mustangs in attendance

Now I am just going to be negative. Sorry in advance. You will not be able to get an FB streetable. If you build something streetable, it will not work as an FB. We ran ~1" front ride height on the FB car. You would get stuck on every speed bump and pavement change and the car would likely be destroyed on the first pot hole. Your car would be so low to the ground that no one would see you and you will be killed in an accident in short order. That doesn't mean you can't take it to the show, it just needs to go on a trailer.

My advice: Get to the track and get involved. With your enthusiasm and FSAE experience you should have no trouble finding someone who will let you help with their effort. You will learn a lot from being around the cars and some of your questions will become clear to you

[AlbertaSpeedShop]

Was thinking street mode is riding on 16s and track mode rides on 13s clearing speedbumps. Kinematics is MUCH less important in the street.

I'm terrified to take it on the highway for not being seen. In town ... maybe ... i donno. I've heard some stories of very sane people. Starting to see more of these KTM crossbow and the polaris equivalent and Ariel atom. I'd be constantly driving defensive as all get up but I'd be willing to do it say 5000km a year or something just leisure craft like

Even with 16s front wing clearance to parking lot entrances is the sketchy bit. If I'm running an H.I.S. like i plan and sprung weakly in warp that should make lot entrances even worse.

[AlbertaSpeedShop]

So Diffusers are supposed to be the most efficient means of generating downforce. It's a surface area thing. And with all the discussion in preshows for F1 since the aero rule changes in 09 talking about the evolution to a high nose design its all about energizing the floor.

However somewhere on here someone mentions high nose is much more drag. Sooooo sounds like you want the energized floor of a high nose without all the drag of air hitting the Tea tray area head on and having to be twisted and warped around the sidepods. .... years ago there was some "Twin Floor" or two floor car where the sidepods didn't touch the floor. Seems like a thing to try??? High nose and energized floor without twisting directing the air around a sidepod? Air can then relaminarize between sidepod and floor and hit the top surface of the diffuser in a clean controlled manner and could clean up some of the stall issues due to rear tire turbulance.

Sound right?

[S Lathrop]

So Diffusers are supposed to be the most efficient means of generating downforce. It's a surface area thing. And with all the discussion in preshows for F1 since the aero rule changes in 09 talking about the evolution to a high nose design its all about energizing the floor.

However somewhere on here someone mentions high nose is much more drag. Sooooo sounds like you want the energized floor of a high nose without all the drag of air hitting the Tea tray area head on and having to be twisted and warped around the sidepods. .... years ago there was some "Twin Floor" or two floor car where the sidepods didn't touch the floor. Seems like a thing to try??? High nose and energized floor without twisting directing the air around a sidepod? Air can then relaminarize between sidepod and floor and hit the top surface of the diffuser in a clean controlled manner and could clean up some of the stall issues due to rear tire turbulance.

Sound right?

One thing that is not given enough thought is how narrow the space between the front tires on a F1 car is. That dictates a lot of the design.

Down force always comes with some drag. There is a point with small bore formula cars that more down force just doesn't increase performance, even in a corner because the car is at the maximum the tires can give.

Now, if your car is a bit deficient in mechanical grip, then more down force will add to performance but you are papering over a more fundamental problem.

While there are bigger tire a FB can run, all those tires are designed for a car that is 200 to 400 pounds heavier. So the smallish FC tires give the best performance on a FB.

Aero balance is just as important as the amount you have. Maintaining balance with changes in speed is a trick often over looked.

[AlbertaSpeedShop]

Sounds like even some rudimentary track maps would go a long way.

Googling those next chance I get

[Chris Livengood]

Your TAG karting experience is way closer to an FB than any auto-x driving, especially that in a production based car, than you probably realize. Go do more karting, get focused on how to improve yourself there, it will mean way more to your eventual use of an FB car than continuing to auto-x. Don't worry about shifters karts either, they tend to train drivers for things that you can't do in cars. If you can get some good seat time in a FF it will be extremely valuable as well.

[AlbertaSpeedShop]

That's what I was saying!!

It wasn't getting any support hahaha. Thanks Chris

[Christopher Crowe]

"There is a point with small bore formula cars that more down force just doesn't increase performance, even in a corner because the car is at the maximum the tires can give."

Steve, I'm trying to fathom this idea. Clearly, there would be a maximum that a tire can give. I suppose that would be the point at which a tire is being used so ferociously that its footprint rubber is no longer flexing, it's simply being shorn away (on the micro level)... and at that point there is no more traction to be had. The tire truly is maxed out.

But is that point anywhere near what the aero down-force on a light formula car could possibly provide to those four tire contact points?

It would seem that even if the aero down-force was many times the weight of the static vehicle, the "maximum the tires can give" point would still be quite some distance away. You'd stupidly fast-heating and fast wearing tires... but the traction would be lavishly increased. At least for a while, until the heat altered all things.

Can you help me on this?

Thanks much,

Chris Crowe

[S Lathrop]

Chris;

A FB can make down force equal to its own weight at 150 mph. And this is not as much wing as you might expect to do that. If you look at pictures of my FC and FB cars, you will see that the FB does not run as much wing as the FC does. But both cars make similar down force at similar places on a track. The difference is that the FB is just going faster and as such does not need as much wing to have the same down force.

When we run the FB with the wing configuration that the FC has, we just don't go as fast. Partly because we don't go down the straights as fast and we don't gain enough or anything in the corners to offset that speed loss.

If you look at tire data, you gain lateral adhesion as you increase down force and camber, up to a point. After that, there is a drop off in lateral adhesion because the rubber is not strong enough and just tears apart and the tire distorts to a point where there is just not as large a contact patch working against the track surface. It turns out that for FC type tires, that optimum vertical load is not all that much higher than the load on the tire static.

[AlbertaSpeedShop]

A simplification seems to have caught you out. Chris, as you don't sound like your familiar with the concepts lets talk tire models.

What's being discussed here:

I suppose that would be the point at which a tire is being used so ferociously that its footprint rubber is no longer flexing, it's simply being shorn away (on the micro level)... and at that point there is no more traction to be had. The tire truly is maxed out.

Is the result of excess slip angle ... usually an amateur driver just keeps feeding the steering wheel expecting more steering force to yaw the car but it's a loosing battle at that point.

The topic being discussed is the tires reaction to weight. We see this in vehicle tuning via anti roll bars or tire pressures or spring rates. When more weight is added to a tire it is able to generate more grip .. however its a function of decreasing gains. Caroll Smith wrote a few books all very good on each topic. Specifically "Tune to win" has an example like this. Your vehicle is on a straight with a 50-50 roll distribution for simplicity.

The front wheels are carrying 250lbs each and tire data shows at 250 lbs and slip angle 8 deg the tire generates 400lbf lateral. So the front axle has the theoretical potential to generate 800lbf lateral. (1.6 times the weight)

Now lets consider at steady state cornering. Where weight has transferred to the outside wheel and with that 50-50 roll distribution the front axle will still carry 500lbs weight it'll just be lets suppose 350lbs outsude tire and 150lbs inside tire. Both tires are at a slip angle where each makes max lateral grip (the slip angle will be different for the weight each wheel is carrying, this is why Ackermann is important. Claude Rouelle has a good article on that). Now the outside tire makes 420 lbf lateral and inside tire makes 255lbf lateral. When we add this up we see 675lbf of cornering grip but still 500lbs weight on the axle. So cornering force is now only 1.35 times greater than the weight.

This is because the lateral & longitudinal grip a tire can generate does not increase as much as the weight is increased.

Suppose we increase the roll stiffness front and rear equally keeping the 50-50 distribution just stiffer. Now in steady state cornering the outside tire might carry 400lbs weight and generate 460lbf lateral, the inside tire carries 100lbs weight and generates 180lbf lateral. So now we have 640lbf lateral for 500lbs weight, or, lateral is 1.28 times weight. This is why increasing stiffness on the roll bar decreases grip on that axle and why you want your car as softly sprung as you can afford to go. Aerodynamics are sensitive to ride height so aero cars are sprung stiffer to affect less change in downforce at the sacrifice of SOME cornering grip. What is lost due to stiffer springs is more than recovered by the addition of aerodynamics.

The function shown to most agree with tire data is named after the man who discovered the correlation Hans B Pacejka.
For cornering its something like:
Fy = D sin [ C arctan {B*a - E (B*a- arctan (B*a))}]

He's written a couple text books. Others have developed tire models. Theres the Magic Formula, Pacejka models, Cosin FTyre, Delft Tyre, Neural Network approxmations and simple Mohrs Circle analogies. There's a 3D Mohrs circle analogy which includes vehicle speed for aerodynamic cars. A temperature sensitivity function can be added. There are several textbooks which ease into the subject matter such as Race Car Vehicle Dynamics, and Vehicle Dynamics; Theory and Application

what it boils down to, is if you choose a tire to small for your car you increase the sensitivity to weight transfer. However by choosing a tire to large there is not enough sensitivity to make adjustments for the driver. Also you struggle to generate any heat in large tires. Racing tires are very sensitive to temperature.

When choosing a tire look at the top speed you expect. A small tire won't be rated to go to speeds as high as 150mph as they rotate much more quickly to acheive that speed and can't handle the centripetal loads it requires. Then look at how much braking potential you need for that speed and the frequency you're going from top speed to a stop. On Road Atlanta every 79 seconds you have that braking zone for turn 10A with turn 8 right before that. How large of brakes do you require? Your tire needs to fit over top of those rotors.

Speed and braking considerations get you in the ball park ... but then you have to try out the tires in your size range to find the ones that heat up enough for you without overheating. That can connect the power potential you have to the track. Some cars have a really wide rear tire; that's because the car span up thinner tires too easily, the driver couldn't get power down. However wider tires are more drag everywhere else. Theres the driveability of the tire too. A stiffer sidewall means the driver inputs are communicated to the contact patch more quickly. That happens in reverse too the contact patch communicates to the driver more quickly. This has been known to catch a driver out and requires sharp reflexes and talent. Stiffer tires are more sensitive to having just the right camber conditions at the contact patch and are more sensitive to weight transfer, camber, caster, KPI, Ackermann, Mechanical Trail, and offset of the pushrod from steering axis if mounted on the upright. Stiff sidewalls are able to hold the contact patch where it is, with less tendency for the patch to curl under diminishing grip, a stiff sidewall holds its position better, transfers more grip, but heats up less. Tires with soft sidewalls are lazy or less reactive. Communicate less and with less urgency, Operate at higher slip angles, are more forgiving and better suited to amateur drivers. From what I've noticed Goodyear makes a stiffer sidewall than Hoosier in general. I can't speak for others.

From what has been mentioned of the Hoosier tires for a heavier car they'd have stiffer sidewalls, take longer to come to temp, be more sensitive to vehicle set up and weight transfer. If you have a target ride frequency then you must run softer springs which means more body movement and less effective aerodynamics. Everything in racing is a compromise

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Mr. Lathrop is using terms which make me cringe inside simply because they're over generalizations however I take his meaning and if that's how he needs to think of it I'll not start an argument of semantics. As long as he knows what he's talking about we can have a conversation on that together. However as you don't sound like your familiar with the concepts lets talk tire models

Might I suggest you adjust your tone somewhat. At least until you have achieved the levels of success on track as Mr Lathrop. Thanks.