Greatest innovation in last 40 years of suspension design?

[HoggyN]

Racecar Engineering, September 2010 p.74

Lancaster Links...

"the greatest innovation in the last 40 years of suspension design."

I just don't get it. They look like swing axles to me. What am I missing?
http://www.noots.org.uk/fs/images/lancasterlinks.jpg

[exFSAE]

There's a reason I no longer subscribe to RCE.

And yea, no different than a swing axle.

Must be some hellacious load on those pushrods.

[Old Greg]

Not quite. Such a setup eliminates two of the big problems caused by swing axles: high roll center and bump steer. It would, however, have even more camber progression in pitch/heave.

It doesn't look like it would have too much camber change in roll, so with some anti-squat it might not be too bad a setup. It would certainly be worlds better than a swing axle.

[Zac]

I dropped my subscription to RCE after the subscription price started to exceed the cover price.

I wouldn't complain about the camber change in bounce, that's a pretty obvious trade-off with that short of a swing arm length. The pushrod setup and rear box however...

[Pete Marsh]

Well at least you wouldn't have to stuff around with Kinematics to find your instant centre. You can touch it!
If you swing the skew axis around by moving the lower fore forward and outboard, the camber gain, roll centre and structure all get better and it can be made to work ok.
Oh wait though, that would be kind of the same as a BMW 2002 or Datsun 1600 (P510 for USA)so how is that an innovation?

Hang on I get get it, they are 60's designs, so older then 40 years , so don't count as innovations in the last 40 years.

Pete

[Neil_Roberts]

Well, it does set a new world record for halfshaft plunge per inch of wheel travel. Maybe the innovation is in deflection steer. Or is it a braking judder generator?

I suppose that the asymmetric rocker axes are mildly interesting. What does RCE claim as the innovation?

[oz_olly]

Just for Pat Clarke's benefit don't forget the rod ends in bending. It is an innovative use of rod ends in bending.

EDIT: On closer inspection the rod end is for the toe link not the swing arm.

On another note I've almost finished reading Think Fast (review to follow in the Think Fast post) but so far so good a really easy enjoyable read and as promised full of gold nuggets. I also love how many Aero engineers have become successful race car engineers over the years, very inspiring.

Cheers

[HoggyN]

Originally posted by Neil_Roberts:
Well, it does set a new world record for halfshaft plunge per inch of wheel travel. Maybe the innovation is in deflection steer. Or is it a braking judder generator?

I suppose that the asymmetric rocker axes are mildly interesting. What does RCE claim as the innovation?

To be fair, it isn't RCE that is claiming that it is the greatest thing since sliced bread, it is the 'inventor', Professor Derek Seward.

Prof Seward has obviously never seen a Hillman Imp... a 1960's rear engined production car that used exactly (to my eyes) the same set up at the front.

http://www.imps4ever.info/tech/sus_line.gif

Anybody from Lancaster care to comment?

[nowhere fast]

Originally posted by oz_olly:
Just for Pat Clarke's benefit don't forget the rod ends in bending. It is an innovative use of rod ends in bending.


Are you sure? I can only see rod ends on the tie rods in that picture.

Huge loads on those pushrods.

[oz_olly]

Ah it seems you're right. I looked a little too quickly.

[exFSAE]

Hadn't noticed the asymmetric rocker axes. Nice.

[Bobby Doyle]

On page 69 of the same issue they say that Maryland pulled 2G in the skid pad event at FSAE Michigan.

[Rotary Sprocket]

Originally posted by exFSAE:
Hadn't noticed the asymmetric rocker axes. Nice.

That's awesome.

I wonder how long it will take for their "rear box" to shear off. It doesn't appear to have any additional bracing other than where it mounts behind the engine.

[HoggyN]

For crying out loud! Have the moderators on this board died?

I posted a reply on this thread yesterday morning. Yes, I admit it, I made the fatal mistake of including a picture. Does this make me a bad person?

Where's my post?

Edit: Make that two posts lost in the ether now.

[thewoundedsoldier]

Funniest part, the front pushrod comes off the top control arm too!!

And really, why run the brakes all the way to the back? So that when you get rear ended you can lose pressure?

[Tom W]

In the article they claim that a key advantage of the setup is shorter pushrods, I think they missed a key design step along the way...

They also claim that the system lowers their centre of gravity, I would guess that those pushrods would offset the angled upper control arms personally, not to mention that those dampers are about as high as they could possibly get.

They also say that they run huge amounts of anti's to prevent pitch and heave.

It seems to me like the whole thing has been designed with absolutely no consideration of forces, then again the article also implies that it is the design of an academic so maybe he specializes in kinematics only :/

[HoggyN]

It seems to me like the whole thing has been designed with absolutely no consideration of forces, then again the article also implies that it is the design of an academic so maybe he specializes in kinematics only :/

His research seems a bit suspect if he thinks that it is innovative.

Hillman Imp front suspension circa 1963...

Link to picture of Hillman Imp suspension (http://www.imps4ever.info/tech/sus_line.gif)

[Kirby]

I am concerned that out of all the innovation that we see in FSAE/FS this is what ends up in RCE.

[flavorPacket]

This is one of the many reasons I no longer subscribe to that magazine.

It's really a shame that they choose to publish such disasters. The negative light shed on FSAE students here damages the reputation of the series with potential employers in racing and beyond.

[HoggyN]

Well, unless I'm very much mistaken, it is a direct copy of the system used on the front of 1963-76 Hillman Imp. I dare say it was used on other vehicles before that.

If you want to see what I mean past cut and past this link...

www.imps4ever.info/tech/suspense.htm (http://www.imps4ever.info/tech/suspense.htm)

I've given up trying to post pictures and links.

[HoggyN]

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

I give up. http://fsae.com/groupee_common/emoticons/icon_frown.gif

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 (http://www.hyperracer.com/hyper-racer/proracer/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 http://fsae.com/groupee_common/emoticons/icon_smile.gif 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" (http://fsae.com/eve/forums/a/tpc/f/125607348/m/73320357151/p/1) 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 http://fsae.com/groupee_common/emoticons/icon_biggrin.gif). 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... http://fsae.com/groupee_common/emoticons/icon_smile.gif

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/showthread.php?8950-Suspension-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/showthread.php?8950-Suspension-Design&p=24347&viewfull=1#post24347

~o0o~

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

http://www.fsae.com/forums/showthread.php?8950-Suspension-Design&p=38691&viewfull=1#post38691

~o0o~

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

http://www.fsae.com/forums/showthread.php?8950-Suspension-Design&p=45363&viewfull=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.)

[BillCobb]

So what do youallz think of this sliced bread ? Forget the electromagnetic Dark Matter Fusion Reactor core element. It made an inactive suspension an active curb jumper.

SOUNDed wonderful (get it ?)1289

[DougMilliken]

Yeah, that little speaker company in Framingham.

Before them there was something quite similar from Aura Systems http://www.freepatentsonline.com/4969662.html in California. This earlier attempt was (from memory) a bit more bulky and difficult to package. Also, they commutated their voice coil with carbon brushes and at the time we talked to them they had not done any durability testing...