1967 Racing cars & Ackerman effect.

Hmm.... something just occurred to me. Did 1967 GP cars use Ackerman effect in the steering, from pictures and so on, I was under the impression that this was only really developed in more recent times... I'm not for sure though, anyone know? Just and observation.

yes they used it, as has every vehicle produced that does not use a rotating steering axle GraDee <[email hidden]> wrote in message news:908s2i$vlv$[email hidden]...

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> Hmm.... something just occurred to me. > Did 1967 GP cars use Ackerman effect in the steering, from pictures and so > on, I was under the impression that this was only really developed in more > recent times... > I'm not for sure though, anyone know? > > Just and observation. > >

As I understand it, Ackermann geometry would have been universal in the early part of last century, but gradually went out of fashion. Steering on modern cars is more parallel. -- Mark Croasdale ICQ 21549408 GraDee <[email hidden]> wrote in message news:908s2i$vlv$[email hidden]... > Hmm.... something just occurred to me. > Did 1967 GP cars use Ackerman effect in the steering, from pictures and so > on, I was under the impression that this was only really developed in more > recent times... > I'm not for sure though, anyone know? > > Just and observation. > >

Mark Croasdale <[email hidden]> wrote in message news:9099eq$o4e$[email hidden]... As I understand it, Ackermann geometry would have been universal in the early part of last century, but gradually went out of fashion. Steering on modern cars is more parallel. Was it oh well, proved me wrong. I might have though the basics of an older car would be to just have everything parallel rather than being major technical.

I feel I have to disagree with that statement, surely the ackerman geometrics are applied to every modern day road vehicle otherwise tyres wouldnt last 20 miles. please correct me if im wrong. > As I understand it, Ackermann geometry would have been universal in the > early part of last century, but gradually went out of fashion. Steeringon > modern cars is more parallel.

I'm sure this is explained in much detail in Milliken & Milliken, but I believe that the Ackerman angle deal has it's largest impact in very low speed cornering where slip angle is almost non-existant. At racing speeds, parallel arms with a bit of toe out may give the best combination of LF and RF tire slip angles, depending on application of course :) Wayne Hutchison "SEM" <[email hidden]> wrote in message news:909er4$lkk$[email hidden]...

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> I feel I have to disagree with that statement, surely the ackerman > geometrics are applied to every modern day road vehicle otherwise tyres > wouldnt last 20 miles. please correct me if im wrong. > > > > As I understand it, Ackermann geometry would have been universal in the > > early part of last century, but gradually went out of fashion. Steering > on > > modern cars is more parallel. > > >

On Fri, 1 Dec 2000, Wayne Hutchison wrote: > I'm sure this is explained in much detail in Milliken & Milliken, but I > believe that the Ackerman angle deal has it's largest impact in very low > speed cornering where slip angle is almost non-existant. At racing speeds, > parallel arms with a bit of toe out may give the best combination of LF and > RF tire slip angles, depending on application of course :) There are lots of different uses of Ackermann's name: -- Ackermann steering = two kingpins, instead of one pivot at axle-center (cart steering). Ackermann gets credit for inventing this (1800's??, anyone know the date?). -- Ackermann angle = the average front steer angle (average of the two front wheels) to get around a turn at very low speed (essentially 0 slip angle). Can be calulated by: Wheelbase/Turn-Radius (in radians, not degrees). -- Ackermann correction = inside wheel steers more than outside, because it is on a smaller circle == toe-out as the wheels are steered left or right. Originally (according to one reference) to keep from messing up the gravel in the driveways of rich folks(!) Depending on the application, cars may have a range of Ackermann correction, from "more-than" geometric Ackermann, to parallel steer, to reverse-Ackermann (toe-in as the wheels are steered). If the turn has a large radius (like many ovals), then the initial toe setting (toe-in or out) may have more effect than any Ackermann correction built into the steering linkage...because the steer angles are so small on a long radius turn. I would guess that the F1 cars in 1967 had a range of different Ackermann corrections (inluding reverse-Ackermann) -- since there were a variety of different chassis designers, each with different ideas about what they wanted. -- Doug Douglas Milliken <[email hidden]> Milliken Research Associates Inc. <shameless plug> <http://www.sae.org/servlets/productDetail?PROD_TYP=BOOK&PROD_CD=R-146>

At the risk of wading rapidly out of my depth, consider that: 1. Steering angles are small except for at low speeds or in extreme conditions. 2. Tyres do not roll without "scrubbing" all the time, even when going in a straight line, and when cornering there is always a difference between the direction the wheels are pointing and their actual track over the ground (slip angle). I think that these days, slip angles are optimised without exclusively following Ackerman principles. PS Having written the above, I have just read Doug's authoritative reply and will bow out gracefully. Incidentally, I always thought Ackerman steering referred to the set up that has all wheel axes intersecting at a single point in line with the back axle. I like the bit about gravel drives - it has a ring of truth to it. -- Mark Croasdale ICQ 21549408 SEM <[email hidden]> wrote in message news:909er4$lkk$[email hidden]... > I feel I have to disagree with that statement, surely the ackerman > geometrics are applied to every modern day road vehicle otherwise tyres > wouldnt last 20 miles. please correct me if im wrong. > > > > As I understand it, Ackermann geometry would have been universal in the > > early part of last century, but gradually went out of fashion. Steering > on > > modern cars is more parallel. > > >

SEM <[email hidden]> wrote in message news:909er4$lkk$[email hidden]... > I feel I have to disagree with that statement, surely the ackerman > geometrics are applied to every modern day road vehicle otherwise tyres > wouldnt last 20 miles. please correct me if im wrong. > I can't say I know really, I just noticed it while driving in GPL and wondered if they really had it or not? I suppose they did.

Wow...a sincere thank you for participating here!!!!!!!!!!!! Especially for wading through all the crap to zero in and give definitive answers to tough technical questions. Marc. "Doug Milliken" <[email hidden]> wrote in message news:[email hidden]... > > On Fri, 1 Dec 2000, Wayne Hutchison wrote: > > > I'm sure this is explained in much detail in Milliken & Milliken, but I > > believe that the Ackerman angle deal has it's largest impact in very low > > speed cornering where slip angle is almost non-existant. At racingspeeds, > > parallel arms with a bit of toe out may give the best combination of LFand

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> > RF tire slip angles, depending on application of course :) > > > There are lots of different uses of Ackermann's name: > > -- Ackermann steering = two kingpins, instead of one pivot at axle-center > (cart steering). Ackermann gets credit for inventing this (1800's??, > anyone know the date?). > > -- Ackermann angle = the average front steer angle (average of the two > front wheels) to get around a turn at very low speed (essentially 0 slip > angle). Can be calulated by: > Wheelbase/Turn-Radius (in radians, not degrees). > > -- Ackermann correction = inside wheel steers more than outside, because

it

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> is on a smaller circle == toe-out as the wheels are steered left or right. > Originally (according to one reference) to keep from messing up the gravel > in the driveways of rich folks(!) > > > Depending on the application, cars may have a range of Ackermann > correction, from "more-than" geometric Ackermann, to parallel steer, to > reverse-Ackermann (toe-in as the wheels are steered). > > If the turn has a large radius (like many ovals), then the initial toe > setting (toe-in or out) may have more effect than any Ackermann correction > built into the steering linkage...because the steer angles are so small on > a long radius turn. > > I would guess that the F1 cars in 1967 had a range of different Ackermann > corrections (inluding reverse-Ackermann) -- since there were a variety of > different chassis designers, each with different ideas about what they > wanted. > > -- Doug > Douglas Milliken <[email hidden]> > Milliken Research Associates Inc. > > <shameless plug> > <http://www.sae.org/servlets/productDetail?PROD_TYP=BOOK&PROD_CD=R-146> >

Actaully when you have the ackerman setup really well you can get away with zero toe. I changed my Solo ll cars ackerman and was able to get the turn in response I wanted without using a lot of toe out up front. The more steering ackerman you have the more the inside tire turns in compared to the outside tire. What it helps is straight line speed since you are not running as much toe out. Most street cars do not have ackerman set for a good crisp turnin at a corner since they want the car to understeer a bit, naturally. Dave