Front Control Arm Upright Mounts

[Brent Howard]

Anyone know how teams mount their control arms onto their upright so that the bolt can pass through horizontally? I know Racetech mentioned one teams, but I can't remember, and teams that run 4 of the same uprights must do this. I'm just running into a brick wall when I think about how the upright must be able to turn wth the wheels. I don't want to inhibit steering for an easier mounting system.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Brent Howard]

Anyone know how teams mount their control arms onto their upright so that the bolt can pass through horizontally? I know Racetech mentioned one teams, but I can't remember, and teams that run 4 of the same uprights must do this. I'm just running into a brick wall when I think about how the upright must be able to turn wth the wheels. I don't want to inhibit steering for an easier mounting system.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[MercerFSAE C. Burch]

I can't remember exactly, but I'm pretty sure that one of the four teams in the design finals had horizontally mounted bolts. Since I've got pictures of Wollongong's, Cornell's, and GA Tech's uprights and none of them mount their bolts this way, it is probably UMC's car, the one I forgot to take a picture of.

-Chris

[Brent Howard]

I think you are right Burch, they were featured in both Racetech and Racecar Engineering...so it's likely them. There are pics of their wheel assemblies in racecar engineering though.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Alan]

It was UMC's car. I've toyed with this idea too. I was going to try designing some high misalignment spacers but the most I could get was 25deg in each direction. I guess implementing this depends on how much Ackermann you run. I am pretty sure I have seen it on Ohio State's car too, but I'm not sure if they did it this past year. Maybe someone from UMC or OSU could shed some light?

Kettering University FSAE

[Ben Beacock]

Would it be possible to achieve a higher misalignment by using an oversize bearing with bushings to use the same size bolt(and spacers as well)?

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph

[yofa]

Alan,

Here's a hint. How did you figure that 25 degrees per side would not be enough for you?

Bob Mai - yofa@shaw.ca
Steering/Suspension
University of Manitoba/Red River College

[mtg]

Pictures of the UMC uprights are on our website.

www.umr.edu/~formula (http://www.umr.edu/~formula)

[Alan]

Yofa,

Here's why I don't think 25 deg isn't enough for our car. Referring to the picture below (pardon the crudeness):

1. According to the rules a hairpin turn has an OD of 29.5' or a radius of 14.75' (177")
2. I am assuming no slip angles to simplify the scenario, all I want is an estimation. I don't think they are high enough on a slow, tight hairpin to throw off the calculations much.
3. t = 50" and l = 65"
http://www.kettering.edu/~lo1224/steer.png
So R1 = 177", R2 = R1 - t = 127"
del1 = atan(l/R1) = 20deg
del2 = atam(l/R2) = 27deg

Based on this I would like more than 25deg. Going back to the thread you started on front wheel steering angles, I agree with what Aaron said about being able to steer even tighter than what is on the course. Plus I like the flexibility of trying varying amounts of Ackermann. Coincenditally our steer angles and % Ackermann our very close to the numbers Frank quoted for their car which had I think 36deg for the inside tire. Also based on driving previous cars, I would like more than 25deg.

Anyway, if my analysis is flawed, please feel free to correct me.

Kettering University FSAE

[This message was edited by Alan on October 05, 2003 at 10:53 PM.]

[yofa]

Ah, the small detail known as the stated rules. If you build to the rules and to 100% Ackerman, Your calculations are correct. I'm not going 100% Ackerman and I'm ignoring that line in the rules, simply because it doesn't make sense.

I'm currently trying to get an accurate track map of this year's event to prove that the 29.5 foot OD of a hairpin is a typo. The same rulebook says that the most slender lane is 14.75 feet wide, which incidentally is the radius of that tightest hairpin. That would mean that they would basically butt 2 minimum lane-widths together with a line of cones down the middle and expect cars to make it around. That would be like expecting a road car to do a U-turn without using the service lanes of a 2-lane highway.

I seriously doubt this and instead think they meant 29.5 minimum hairpin turn radiis. I'll send the e-mail to the judges once I get that track map. Designing for these wild angles would compromise suspension compliance.

Of course, I could be way wrong, which would mean significant redesign...

Bob Mai - yofa@shaw.ca
Steering/Suspension
University of Manitoba/Red River College

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Yofa:
That would mean that they would basically butt 2 minimum lane-widths together with a line of cones down the middle and expect cars to make it around. That would be like expecting a road car to do a U-turn without using the service lanes of a 2-lane highway.
<HR></BLOCKQUOTE>

You've obviously never driven at competition. Why assume the rules are wrong? Sounds like a bad assumption, especially if your design requires them to be wrong! http://fsae.com/groupee_common/emoticons/icon_eek.gif

A 'hairpin' is not necessarily a 180 degree turn, so a turn that tight does not necessarily have to have a line of cones down the middle. But they are not far off. http://fsae.com/groupee_common/emoticons/icon_wink.gif The hairpins do not comprise most of the course but they are there.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on October 08, 2003 at 01:23 PM.]

[Alan]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Yofa:
The same rulebook says that the most slender lane is 14.75 feet wide, which incidentally is the radius of that tightest hairpin.
<HR></BLOCKQUOTE>

If you look at the Autocross rules, the minimum track width is 11.5 ft.

We don't have a map of the autocross, but our endurance map shows some of the corners to have radii much smaller than what the rules state. I wasn't a driver but I do recall the series of turns immediately following the start/finish line looked like they were very tight. Our track map confirms this.

Kettering University FSAE