Benefit of Pilette suspension design

[christopera]

scarbs, They appear to be solid, with no connections. The front bar is centered using jubilee clips, apparently. I guess they could be rigging bars.

This is what I was thinking but was beat to the post.

[christopera]

It appears as though camber change under heave would be minimal, that said it looks like it would be a disaster from a camber standpoint under roll. Additionally, given the position that the ARB is in, even given the stoutness of the ARB itself, roll stiffness must be quite low. The motion ratios of the ARB spring are complex and difficult to immediately internalize for me.

[DaveW]

It appears as though camber change under heave would be minimal...

True if the pull rods don't change length.

...it looks like it would be a disaster from a camber standpoint under roll.

Perhaps that is the source of some of the eight seconds...

Additionally, given the position that the ARB is in, even given the stoutness of the ARB itself, roll stiffness must be quite low.

Not sure about that... The rear bar looks fairly conventional, complete with adjustable arms. The front looks to be a combined bending/torsion bar, curiously with no adjustment - but it could be stiffest bar, I suppose.

[scarbs]

I see what you mean, but i'm not sure I agree. These rods appear to be on the car when bodywork is fitted, with fairings mounted around them.

[bill shoe]

The solid bars are structural supports (spars) for some of the extra wing elements that are in unusual locations. The underlying Ralt chassis was not designed to mount wings in those locations, so improvised spars/mounts had to be made that attached to the car through suspension hardpoints on the monocoque and gearbox.

These bars seem to be attached to the car with reasonable looking clamps. The front bar piggybacks on the steering rack mount, and the rear bar piggybacks on some wishbone mounts. Not sure why the front also has jubilee clips, they do not inspire confidence...

[hardingfv32]

Can we assume that the designer, Martin Ogilvie of Lotus, had some comprehension of the complication he was creating with this design?

So what would have been his main goal in a 94' F3 car, aero or mechanical grip?

IF aero, then how can the suspension be of help? Say, ground clearance control for example.

Brian

[DaveW]

The solid bars are structural supports (spars) for some of the extra wing elements that are in unusual locations....

The 10 picture in the carsales sequence does suggest that the front bar supports the trailing edge of the front wing. On the other hand, the first picture in the sequence suggests otherwise. Perhaps two alternative wing configurations are shown.

So what would have been his main goal in a 94' F3 car, aero or mechanical grip?

The suspension of any aero vehicle must pay deference to the requirements of aero. Certainly since 1994, however, teams running F3 vehicles also took care over mechanical setup if they wanted to be competitive.

[Tim.Wright]

Not sure I'd want anything to do with that.

Well let see if the specs from the carsales page can change your doubting mind;

Front Suspension: excellent--black
Rear Suspension: excellent--black
Shocks: special

What do you say about that??

Tim

[bill shoe]

The solid bars are structural supports (spars) for some of the extra wing elements that are in unusual locations....

The 10 picture in the carsales sequence does suggest that the front bar supports the trailing edge of the front wing. On the other hand, the first picture in the sequence suggests otherwise. Perhaps two alternative wing configurations are shown.

I think the 1-picture shows a relatively stock Ralt aero package, and the 10-picture shows the same aero package with the addition of the full-on batman pieces. Maybe the photographer wanted to show that the additional aero parts can be easily removed but did not bother to remove the corresponding spars.

Suspension specs -- . At least the seller doesn't make stuff up.

[hardingfv32]

in the other photos in the car-sales site, there were extra springs, the large ones clearly for the strut part. there were also much smaller, much-higher-rate ones in there too, and i'm not sure they would fit along with the strut, where would it go? i would assume the strut shaft would need to be larger in diameter than the I.D. of the small springs... so they could go along with the pull rods, allowing a mechanism to slide..

The boxes also show a number of sleeves that would help the small springs nest inside the large springs. It would make for a small strut shaft as you point out.

Brian

[hardingfv32]

Count Van der Stratten, the guy who paid the bills, had been around a lot of race cars. He would have been as perplexed by this design as we are when he first saw it proposed. There had to be a "reasonable" theory or purpose for it's design. We have just not found it yet.

Does this car look unusually slim by standards of the day?

Brian

[bill shoe]

Brian, thanks much for the initial post on this car. Yea, the rear end looks especially slim because the exhaust stays in the central part of the car. As I was looking at all these pics I did notice how nice the '94-era Ralt looked.

Happy Thanksgiving, and here's hoping that Webber can get a win from Brazil!!

[Jersey Tom]

Can we assume that the designer, Martin Ogilvie of Lotus, had some comprehension of the complication he was creating with this design?

That's a big assumption.

There had to be a "reasonable" theory or purpose for it's design.

Maybe there was. Doesn't mean it worked.

[hardingfv32]

I view this discussion/design like generating power from nuclear fusion. We know it is better than nuclear fission, but we do not have the a design that makes it possible at this time.

This design has a goal, unknown at this time to us, that required the use of a strut system inside the wheels. These struts could well be an engineering or materials problem that was never solved correctly. That does not negate the value of the underlying goal.

Brian

[PlatinumZealot]

The is a 1994 Pilette F3 car with a very unique suspension design (same front and rear). What are the possible benefits of this design? All I can come up with is packaging. No rockers or coil overs on the chassis.

http://www.race-cars.com/carsales/other ... 4046ss.htm

Brian

I think kinematically this is quite conventional to the Double wishbones used currently in F1.

It is a pull rod suspension as you see.

The weird part is that the antiroll mechanism is only just mounted on separate oversized "sway bar" links.

This wouldn't be out of the norm for street car suspension with outboard sway bar links.