Pellerin reactive suspension

[Luceastman]

http://www.ten-tenths.com/forum/showthr ... ost3076300 is the where I first wrote about this for the first time in many years. I will copy paste for you but first, i would like to say that the arrangement shown here above is what was used in the first pattent I applied for. It was never used as such. In fact, the arrangement changed considerably.
I read some of the things writen above and it is clear that it is not clear for many how roll stiffness is obtained. If people dont insult me and call me names, I may want to provide more explanations on how it was best used. My email address if you want to reach me is luceastman@hotmail.com

Here is what I wrote before:

Hello. I am the guy that invented this so called reactive suspension. More or less 12 years have gone by. i never made a penny from this project but it allowed me to live my passion. My system was used at Arrows F1 when Mike Coughlan was Chief Design Engineer. It was only used in one track testing but it proved the principle. it was only fitted in the front of the car. The roll stiffness increased with aerodynamic down force which developed high speed under steer. A few weeks later, the team ceased its operations. Unfortunately, the system had not been fully tested and developped to itsmfull potential but... Mike Coughlan remainded a friend. He is the only one that beleived my system had merit.
In my book, Mike is the best racecar engineer in the world. If I recall correctly, McLaren won 3 Constructors championship under his direction as Chief Design Engineer.
Most of you know what happened to Mike after those success. I will not comment and I hope there will be respect for the man that paid a heavy price for what he was blamed for.
Last week, i watched the Spanish GP and I had a shock. Williams F1 won the pole and went on to win the race. This is extraordinary!
Mike Coughlan started working for Williams last fall 2011.
This proves clearly that Mike is the best Engineer. Out there.

Now about my suspension system, I will say that I do not think it was ever used to the full extent of what i had designed. If it was, nobody came to tell me but when a man of the caliber of Mike Coughlan tells you it is a very clever idea, it means something.

This project allowed me to meet men like Pat Simmonds, Adrien Newey, Steeve Nichols. I Met them all in the UK with a scaled model that I had built.
The meetings all went like this. initially, i would be greeted by a junior engineer that saw my mockup. I never took long to see the guys I mentioned above to come see this idea.
Adrian Newey than at Williams in the Jacques Villeneuve days was very impressed. He had lunch with me and they showed me the trophy room. They all promissed me a study and that they would get back to me.
Apparently, in those days, packaging was a problem. Plus, for every dollar spent, the best results were from working on aerodynamics. Mike tells me it is still the case after all these years.
Let me say that I do not think they used my system. My system did two things. First, it connected the two sides of the suspension allowing to use a single spring. Secondly, a very clever rocker arrangement generated self centering force that was proportional to vertical load.
In those days, everybody was using four springs with rockers and a sway bar.
Doing my presentations, I realised that they liked the first part very much. I could see the lights in their eyes.
Nowdays, many cars use a single spring. I like to think I made them realise.
I think McLaren were the first to incorporate this.
I can only guess but in the following years, the race community was talking about the McLaren suspensions. But my guess is also that they never used the full system. Even when Mike Coughlan was there.

I had two patents on this thing which was kind of stupid, I admit to this because it is all secret what they put in those cars. So I ended up loosing mucho $$.

I have no hopes other than one day, some team will use my system to the fullest extent, front and back of the car. Thensystem is described in detail in the 1999 thread.
Thats it for now Friends.
I have pics from those days that prove where I have been. So dont call me names unless you are willing to give your real name.
cheers!
Luc Pellerin
 

[DaveW]

Brilliant...

Luc, As I understand your patent, the one that listed the diagrams posted by Belatti, any net side force (left - right) input by the push rods will be reacted by a force equal to the spring stiffness multiplied by a number that depends upon geometry of the mechanism. I realize the the number is likely to vary with position, but I would like to know how you compute that number for small displacements.

As silente pointed out, your concept appears to be very similar to the "Monoshock" layout used for a number of years by Dallara & others. Question: Is it similar, & if so did your concept pre-date the Dallara version?

[Luceastman]

One has to tell me how I can post images. It would help me to explain.
Also, if you have a link or something to show what was used in Dallara & others?
The only system I knew prior to inventing this system was the Van Diemen F1600. If some of you think it is the same, you must be thinking that part 36 is moving laterally between springs. This is not the case. Read again the patent material.

One thing I can say is that roll stiffness is totally independent of sping stiffness. It is strictly dependent of the load applied on the spring. (between points 58 and 56. )
To explain roll stiffness, viewing fig 9, imagine the motion of poit 58 in an arch of center 56. Line 56-58 will become offset with point 44a. This offset is directly proportional to chassis roll. This offset creates a moment around point 44a that is equivalent to the perpendicular distance of the offset to point 44a multiplied by the load in the spring. (independent of spring rate)
The amount of roll stiffness is adjusted by varying the ratio of lever 44a-58 / 44a-68. As one can see, the shorter the distance between 44a and 68, the greater the rotation of 44a-58 resulting in a greater offset distance of the line 56-58.
Ounce you understand the principle it can be repackaged as we did to accomodate rockers and dampers.
If I know how to post images I will be able to show more arrangements.
For now, I got to go. Take care and talk to you later.
Luc Pellerin

[hollus]

How to post a picture

[DaveW]

Also, if you have a link or something to show what was used in Dallara & others?
The only system I knew prior to inventing this system was the Van Diemen F1600.

I think the V-D would be similar. A couple of pictures lifted from insideracingtechnology.com (front & rear):

One thing I can say is that roll stiffness is totally independent of sping stiffness. It is strictly dependent of the load applied on the spring. (between points 58 and 56. )

Thanks for your explanation. I omitted the first order effect in my "reading" of your patent. Would a roll stiffness dependent primarily on instantaneous vertical load not be a little too inconsistent, or is that the objective?

[Luceastman]

Thanks for the pics Dave. It seems we have come to a mutual understanding of the basic principle. Indeed the Dallara and VD were the same. The problem with this type of monoshock arrangement is that they had to adjust the roll stiffness by selecting springs that would limit the lateral motion of the center rocker assembly. As you can imagine, in a one wheel bump situation, and with stiff lateral springs, you ended up lifting the opposed wheel. Not very good.

As for your comment about '' roll stiffness being dependent primarily on instantaneous vertical load not be a little too inconsistent?''
My reply to this is
1) It is recommended to keep a preload on the spring plus you always have dampers on each side. This is part of the testing that need to be done. Modeling in ADAMS or other would be required.
2) What you get in roll stiffness is what you need. Tire grip will be null if you have no vertical load. With modern day F1, will all the aerodynamic load, I dont expenct this to be a problem.
3) There is a stong possibility, one would want to use some kind of conventional springs in combination with this system.
For example, the third spring would engage only at high speed to add roll stiffness.
Remember, the objective is to remain 'complyant' at low speed. Otherwise, very stiff suspension is like putting a shim under one leg of a table.

I have had proplems embedding images in here. Hope this works.


if not try this:
https://skydrive.live.com/?cid=098018e9 ... &sc=Photos
Lets see if it gets posted and than we can talk.
Luc

[DaveW]

It is written deep into my untutored & slightly damaged brain that the mechanical lateral balance of a vehicle is determined by the proportional of the roll moment carried by the two axles in a turn, all other things being equal.

Experience has taught me that a c.g. that is offset from the centreline of an otherwise symmetrical vehicle is not a good idea. This is because vertical and warp responses become coupled, and vertical inputs cause the lateral balance to be disturbed. Even when a vehicle is highly unsymmetrical, as in "oval" set-ups, it would seem that adjusting corner damper settings to minimize the coupling of vertical & warp responses "settles" a vehicle (driver speak).

It occurred to me, Luc, that your design might, perhaps, cause vehicle balance to become inconsistent as a result of transient warp loads in the presence of vertical inputs.

[Luceastman]

First time I hear of transient warp load. I do not mean to debate. I am simply exposing a way to control roll other than torsion bars and springs.
Not too sure what you mean but I will say that when a chassis roll, you do have an offset of the c.g. nomatter what type of suspension.
The chassis will roll up to a point where the reaction of the sway bars, springs and / other will equal the roll moment.
The roll moment will be offset by the combination of the front and back of the car. By design, if you want a car to understeer, you make the front stiffer than the back and vice versa for oversteer.
My system will to exactly that by design of the triangular piece. No need to play with springs and sway bars.

[Tommy Cookers]

It is written deep into my untutored & slightly damaged brain that the mechanical lateral balance of a vehicle is determined by the proportional of the roll moment carried by the two axles in a turn, all other things being equal.

Isn't the proportion of the 'overturning moment' carried by each axle the important factor here ?

The lateral 'weight transfer' is the sum of the weight transfer associated with the compression and extension of the suspension , and the weight transfer from the force system in the suspension linkages due to cornering.

The roll moment (proportionate to the CG height above the Roll Centre(s)) is only the first part of the WT, and adjustment of roll stiffness afects only this part, (if the roll centres were at CG height there would be no roll due to suspension compression/extension, ERA owners will appreciate this point)


Total Lateral Load Transfer (Distribution) is the Millikan's term for this sum.


So (I'm trying to think), does this have anything to do with the suspension under discussion in this thread ?

[GSpeedR]

A very unique property of this suspension is that the roll stiffness of an axle (in isolation, for the moment) will be dependent upon the instantaneous force in the center spring, which will be directly proportional to the vertical/heave load of the axle. Unless the front and rear axles are identical, this will result in coupling between warp and heave load. I believe that DaveW is stating that such coupling (which exists for laterally offset CGs, for example) is often troublesome to the driver and he often seeks to minimize it. Stockcars will often use this 'feature', created more by their asymmetric wheel rates than their offset CGs, to control lateral balance. It may very well be the case that such behavior is far less important than other benefits offered by the Pellerin suspension, but it is interesting none the less.

Luc: It is a fantastic design. Thank you for sharing.

[Tommy Cookers]

Thank you, indeed !


In old terminology, at any and all instants, the front roll stiffness is proportionate to the instantaneous (vertical) wheel loads at the front and the rear roll stiffness is proportionate similarly to the rear wheel vertical loads ?
That is the roll stiffnesses are varying, together and seperately.

But the front and rear must have the same deflection in roll as they are connected by the chassis.

Doesn't this mean that the load distribution due to roll stiffness is often less than ideal (regardless of CG position) ?
(this would include some situations that the inventor used to show the limitations of existing designs)

Ideally we want roll stiffness proportionate to slowly varying load (aero) but relatively constant for bump loads etc ?
(clever damping may be helpful ?)

I'm thinking that modern high aero F1 has chosen rather high roll centres to reduce roll at source (because of the limitations of anti-roll bars with aero etc as the inventor says).
With little wheel travel (except in single-wheel situations over kerbs) we don't need the 'classic' lavish suspension geometry (camber gain without scrub) that required lower roll centres, we just have relatively large static negative camber at the front.

[Luceastman]

Thank you GspeedR and Tommy for your comments.

[Powerslide]

Remembered the first time I saw reactive system on another forum and thought "I drew that before, way back". Did it just to see possibilities of a monosprung axle but none of the technicalities of course other than to have articulation while load is sustained which also serve well over a curb. A high load inner wheel might lift load on the outer wheel suspended by a hard rear suspension but with this, it could balance it out. A modern interpretation of Pellerins idea was also though off and drawn, here it is (way after).
I think its very clever how it is designed around being effective in responding to aerodynamic demands. It also tends to put the spring where the load is, of course, not passenger car friendly. Didn't they use it in CART?