F1technical.net

Came across this today
love the testing at the end
[youtube]http://www.youtube.com/watch?v=qo1VIUou ... creen&NR=1[/youtube]

Thank You, very interesting and well done.

Merry X-mas.

Amazing video! Thanks

Thanks =D>

Excellent. Mentions improvements to ride that occured in 1934. Maurice Olley was the GM engineer who was largely responsible for creating modern primary ride at that time. A couple other people, I think academic types, fleshed out the theory before then but Olley brought the theory home with an effective program of rig and road testing.

Here's a Milliken presentation about Olley, good stuff--
http://www.millikenresearch.com/Maurice ... lliken.pdf

Olley himself wrote a great article for Road & Track in the late 1960's called "The Flat Ride". It's extremely well written and understandable by non-engineers.

Why exactly did the front springs need to be harder than the rears?

bill shoe wrote:Excellent. Mentions improvements to ride that occured in 1934. Maurice Olley was the GM engineer who was largely responsible for creating modern primary ride at that time. A couple other people, I think academic types, fleshed out the theory before then but Olley brought the theory home with an effective program of rig and road testing.

Here's a Milliken presentation about Olley, good stuff--
http://www.millikenresearch.com/Maurice ... lliken.pdf

Olley himself wrote a great article for Road & Track in the late 1960's called "The Flat Ride". It's extremely well written and understandable by non-engineers.

Bill do you have a copy of this article my googling has produced nothing.

Don't have a copy on me. Have one at work, I'll try to get it in Jan.

It was from Road & Track, October of 1967, 68, or 69.

AFAIK this IFS revolution was done to allow the engine/gearbox unit to be be moved forward into the axle line region
this increased the pitch period to be close to the bounce period, so eliminating the pitch/bounce interference 'beats'
(that give the 'head nodding' ride characteristic of cars with beam axle front suspension)
it would be nice to see Mr Olleys account

it seems that GM first went to SLA (wishbone), then 'knee action' (Dubonnet?), then of course back to SLA or struts

but some small trucks, pickups, vans and 4x4s still have (or had till very recently) a front beam axle ?

Primary ride theory (pre-Olley) suggested--

1. pitch frequency should be same as bounce frequency.
2. front and rear static deflection should be same.

Olley tested these concepts with in-car subjective eval and confirmed that both were approximately correct. However, he fleshed it out in more detail than theory could predict--

1. pitch frequency should be slightly faster than bounce.
2. front static deflection should be slightly larger than rear static deflection.

These changes created a much more grounded and positive feel for the passengers than the floaty and detached feel of the "pure-theory" setup.

I've often wondered if Indycars on superspeedways would benefit from placing ballast in the nose and tail rather than the middle. This would make pitch slower and more stable (closer to bounce freq) and the resulting slower yaw freq would do little harm (maybe??) in an environment where the yaw velocity is very low. I think some of the potential benefit of Mercedes-style linked suspension in F1 is to get pitch freq similar to bounce freq, while keeping the yaw moment low for quick transients.

bill shoe wrote: Here's a Milliken presentation about Olley, good stuff--
http://www.millikenresearch.com/Maurice ... lliken.pdf

I have to admit to never having heard of Olley before. It's funny how the people who make a real difference in this world are often mostly unheard of and from "poor" backgrounds. He grew up in North Wales - an area not known for being prosperous then or now (except for a few mine owners of course).

Also interesting that lawyers jumped on his work and prevented its dissemination. Again, nothing changes in the corporate world it seems.

Thanks for the link.

mep wrote:Why exactly did the front springs need to be harder than the rears?

IIRC the 1936 footage says the front springs are hard to be stiff enough to locate the front axle well enough eg for good steering
at that time there were no suspension linkages, the springs did that job
softer springs would make worse steering 'shimmy' (an oscillation due to gyroscopic reactions to single wheel bump)

bill shoe wrote:Here's a Milliken presentation about Olley, good stuff--
http://www.millikenresearch.com/Maurice ... lliken.pdf

A excellent reference, I could hear Bill's voice when I read it.

I'm sure there are many others, but here is an extract from a book that quotes Maurice Olley (you should to back-track to the start of the section for the full story).

The set-up of most modern road cars still follow those "golden" rules, although there are exceptions that suggest they may not be so necessary if the vehicle is properly damped. It is fair to say that Robin Sharp disagrees with that, but (annoyingly) I have been unable to unearth the paper that states his reasons.

DaveW wrote:The set-up of most modern road cars still follow those "golden" rules, although there are exceptions that suggest they may not be so necessary if the vehicle is properly damped. It is fair to say that Robin Sharp disagrees with that, but (annoyingly) I have been unable to unearth the paper that states his reasons.

Here's a link to the Sharp paper--
http://www2.ee.ic.ac.uk/cap/publication ... lt_pap.pdf

This paper gives a new perspective on some of the classic primary ride stuff and fleshes it out in more detail than I've seen elsewhere. For example, he creates a car model and varies parameters (springs, dampers, etc.) to determine the sensitivity of primary ride motion to those parameters. This is how he concludes that dampers have little influence on primary ride (at least for the street-car-type range of parameters he considers).

I think figure 9a is the John 3:16 of primary ride.

I heard of an interesting application of this paper. An engineer used Sharp's paper to set up a pro drift-car for very high slip angle driving. Instead of the traditional front vs rear axle formulation he used a three-part setup consisting of leading wheel, diagonal axle, and trailing wheel (and corresponding diagonal "wheelbase"). The new setup nailed the primary ride and made it much easier to drive.

bill shoe wrote:Here's a link to the Sharp paper--
http://www2.ee.ic.ac.uk/cap/publication ... lt_pap.pdf

This paper gives a new perspective on some of the classic primary ride stuff and fleshes it out in more detail than I've seen elsewhere. For example, he creates a car model and varies parameters (springs, dampers, etc.) to determine the sensitivity of primary ride motion to those parameters. This is how he concludes that dampers have little influence on primary ride (at least for the street-car-type range of parameters he considers).

Many thanks for that.

Without doing too much thinking (which I should), here is a plot extracted from a series of road car rig tests. The tests were largely ad-hoc, but always included ballast representing a driver & passenger, and were usually fuelled. I have attempted to draw a "trend line" (shown in black) through all results for which the frequency ratio is < 1. Interestingly, those results include most high performance rear & mid engined cars, but also a Citroen Zantia, a Viper, an Esperante, a Jaguar, and a Lexus 430.

Edit: I modified my plot to include some (randomly selected) F1 numbers extracted from the last few years - just to keep things more-or-less on topic.