Greatest innovation in last 40 years of suspension design?

[HoggyN]

Three of my posts are now awaiting moderation.. all attempts to post a picture or a link.

I give up.

All I will say is... Hillman Imp front suspension. 1963 and exactly the same set up as the Lancaster car.

[FS Alum]

Guys,

it's a bit out of order for you all to be slagging off these guys' car. In the article it's the faculty advisor that's making all the claims, so you never know if team were "encouraged" to this solution or not. The advisor and RCE are fair game, but cut the team some slack.

[HoggyN]

Originally posted by FS Alum:
Guys,

it's a bit out of order for you all to be slagging off these guys' car. In the article it's the faculty advisor that's making all the claims, so you never know if team were "encouraged" to this solution or not. The advisor and RCE are fair game, but cut the team some slack.

One of our team spoke to them at FSUK and it was clear that they had been "encouraged". That pic is their 2009 car, by the way.

[mrdben]

I think this trend is catching on.

http://www.hyperracer.com/hype...oracer/pictures.html

[flavorPacket]

Originally posted by FS Alum:
The advisor and RCE are fair game, but cut the team some slack.

It's the team's name on the side of the car, not the advisor's.

[MH]

Originally posted by mrdben:
I think this trend is catching on.

I like it!! Especially the rodends in bending But to be fair, it IS shiny!
(Some people should stick to karting IMHO).

regards,
Miki Hegedus
Delft University of Technology

[Chevalier]

Evening everyone,

Long story short, I was the team leader of the 2009 Lancaster team and whilst this evening thinking back to my uni days I found this thread and was surprised to see a picture of "my" car. I know the original post was three years ago and the original posters are probably long gone but I felt compelled to respond and defending things. I would be interested in discussing things further if people are interested too.

Firstly that year we had a team of just five masters students (two of which were useless and just made more work for the other three!) a bit of help from some 3rd years, and a budget of about £10k for EVERYTHING including events costs etc. We also did a lot of the fabrication ourselves. I cut/welded most the chassis and did a lot of machining of components myself. It was a car the team built, not a car a sub-contractor or technician built. So with such finite resources a lot of things just got built after five minutes of back of fag packet design.

Anyway to answer a few questions/comments:

- There are no rod ends in bending. Also the LL system reduces the number of rod ends required as the inner pivots only require bushes rather than rod ends.

- The LL system has the advantage that it has excellent camber control in roll but sacrifices camber control in bump. This I think is obvious to all.

- For FS at Silverstone the track is flat so bump isn't really a problem and Braking/accelerating is controlled with a good dollop of anti-squat/anti-dive.

- In its "pure" form the links would join at the middle. By moving them slightly apart you encourage a small amount of camber gain in roll to compensate for compliance/tyre deflection that pushes the wheel into positive camber.

- The car can be set up with very small static cambers to improve traction.

- In ordinary double wishbone set ups the top and bottom bones are in tension/compression respectively. By joining them up at a single node these forces into the chassis are "cancelled out" to some extent.

- Yeah ok the rockers and push rods don't look great (in fact the car looks rather un-set-up in that pic). The judges panned us for the angles of these. But they were just put there cos we needed somewhere to put them (built not designed!). Another possible disadvantage, you must use push rods.

- The hyperbole of "best suspension in 40 years" or whatever I think is just the journalism. They have to make a magazine interesting to read. It's not a technical paper after all!

- Driveshaft plunge was a bit of an issue, in fact it caused an unforseen problem on the test pan at the event so we missed the early dynamic events whilst this was repaired.

- Brake lines at the back is criticism for the sake of criticism. Utter rubbish! When has any FS car suffered a rear end shunt?! A shunt from what? In the very very chance event that it did happen the fronts would still do plenty enough braking to pull you up safe anyway.

Anyway, it finished the endurance event. Better than many other could achieve (including, I remember the Red Bull team (Graz?!)). And survived a spin and backwards trip into the gravel! Zero driver training and not having time to sort the traction control plus a damp track meant we were slow and sideways; but the concept worked!

If the LL system was developed to a level that double arms are by every team every year I can't see why they wouldn't work. Maybe I am just blinkered in defending my car!

Interesting to enter into discussion on this if people want.

Cheers all,
Malcolm

[Z]

Originally posted by Chevalier
Long story short, I was the team leader of the 2009 Lancaster team ...
...
If the LL system was developed to a level that double arms are by every team every year I can't see why they wouldn't work. Maybe I am just blinkered in defending my car!

Interesting to enter into discussion on this if people want.

Malcolm,

Your LLs have recently been discussed on the "Suspension Design" thread. The link starts you off on page 1, but the LLs don't get a mention until about the bottom of page 9 (there were various philosophical issues that had to be settled before actual suspensions could be discusssed ). Page 13 has a sketch you may find interesting.

In fact, if you cut-and-paste your above post onto the Suspension Design thread, then it may help future teams that are thinking of going that way...

Z

[Dunk Mckay]

I'm reviving this thread, as I've been thinking about the Lancaster Link a lot lately (primarily out of boredom), and I'd like to question a statement made by Malcolm.

I would have gone to see if it was discussed in the "Suspension Design" thread Z linked to, but apparently it no longer exists.

- There are no rod ends in bending. Also the LL system reduces the number of rod ends required as the inner pivots only require bushes rather than rod ends.

How are the inner pivots of an LL setup any different to those of a traditional A-arm? They both pivot about a single axis.

I've been trying to picture in my head how the forces work. But the conclusion I come to is that LL is just a special case of double A-Arm where the geometry means the upper and lower inboard nodes merge. If you could have the two "phase through" each other as if the other wasn't there, you wouldn't suddenly use bushings instead of spherical bearings.

So if rotation about a single axis is the only degree of freedom that is needed, then a tightly toleranced set of shoulder bearings would do just fine, wouldn't it?
The only advantage that comes to mind for spherical bearings is that the bolt used can be aligned so it is in pure shear, instead of aligned with the axis of rotation. This also means that the mounting brackets are aligned in tension & compression, not bending.

But more or less the same applies to LL as it does to double A-Arm.
Admittedly the force going through are no longer always along exactly the same axis, but they are on a single plane defined by top and bottom arms that meet at that point. So if your bolt is perpendicular to that plane you still achieve pure shear, no bending. And the bending in the mounting brackets is minimised.

The only thing I haven't considered, that I'm aware of, is chassis torsion. But my gut tells me that's not the answer.

[Z]

Dunk,

I would have gone to see if it was discussed in the "Suspension Design" thread Z linked to, but apparently it no longer exists.

When I gave the link above it pointed to the OLD version of this FSAE Forum, prior to The Great Forum Shift of sometime around 2013 (?).

Sadly, the hosts of this Forum didn't bother updating the Old Forum links to their new addresses, something that should have been easy for the "computer generation". End result is that much of the "knowledge resource" that was available on these pages is now LOST. Or, at least, "Error 404 - Page Not Found"!

Anyway, here are some links to that thread from my manually updated file. I quickly skimmed through the thread again just now, so some social commentary also added.
~o0o~

"Suspension Design" thread, NEW FORUM, Page 1.

http://www.fsae.com/forums/showthrea...pension-Design

This thread is now 30+ pages long. Note that references to page numbers given prior to about 2013 do NOT match the page numbers as they are now.

Early in the thread (page 2 NF?) I list the major suspension types used on all vehicles for the last 100+ years. I then try to get a "big picture" discussion going on the relative pros and cons of these different suspension types in the context of FS/FSAE conditions. There follows at least ten pages of the villagers screaming blue murder, raising their torches and pitchforks, and doing their best to get the heretic Z burned at the stake.

It is really quite extraordinary how great is the resistance to even DISCUSSING alternative suspension types. Especially on this, a supposedly "Educational" and "Engineering" forum! Many of the "How dare you suggest we do anything other than Double-Wishbones-With-Push/PullRods&Rockers!!!" posts are at the extreme end of the religious zealotry spectrum. Amusingly, more than a few are straight out of the movie "Idiocracy" (eg. see the courtroom scene in the movie for a close parallel to the first third of the thread).

The discussions of the Lanc-Link are of the same nature. NO calm, rational, technical, (boring!), logos-tical type analysis. Instead, just pure PATHOS.
~o0o~

"SWING-ARM Suspensions" post, page 18 NF. No sketches here, just words.

http://www.fsae.com/forums/showthrea...ll=1#post24347

~o0o~

My comparison of the Lanc-Link and Double-Wishbone, near bottom page 22, NF.

http://www.fsae.com/forums/showthrea...ll=1#post38691

~o0o~

"Semi-Leading&Trailing Swing-Arms" post, with sketch, near top page 25, NF.

http://www.fsae.com/forums/showthrea...ll=1#post45363

As I note in the post, this is my "second favourite" suspension for FS conditions. This is primarly because of its extreme SIMPLICITY, which then leads to a very quick build of a lightweight yet VERY RUGGED suspension AND chassis.

Most surprisingly, given above benefits, I have NEVER seen this suspension type in FS/FSAE. Note that the "LL" is more of a "pure Lateral-Swing-Arm", namely with a longitudinal pivot-axis, rather than the S-L&T-SA's angled pivot-axis in plan-view.

When I have suggested this suspension type to students they have, invariably, expressed doubts about it, usually because they have "...difficulty understanding it..."!!! Aaarghhh!!!!! Should I laugh or cry...?

I recently saw this layout on a high-end lawn-mower. The execution was much cruder, with RHS steel tubes for the arms rather than my tapered tubes, but it appears lawn-mower manufacturers can understand it...
~o0o~

Anyway, whatever FS/FSAE claims it is doing, it is NOT EDUCATION!

Mumble, grumble... better go and kick something...

Z

(PS. In FS conditions, all the above types of Swing-Arms, with suitably wide bases at the chassis end, can be done with two small rubber bushes to form the revolute-joint pivot-axis. All very simple, very quick to build, very strong.)

(PPS. If "Bane" is reading this, then I tried to reply to your PM but couldn't because I don't think you are properly registered. In short, tell your team leader he is an IDIOT. Also, check "the prior art", specifically GFR and Monash's suspensions over the last ~5 years.)