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 Post subject: Re: CC&AR Revisited
PostPosted: April 2, 2017, 8:33 pm 
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Isn't the RC car at the top of the thread a fixed length axle?
Seems like if I just think of the fixed length axle as the lower arm (which it is) then this may in fact be feasible.
If it works for the Spitfire/GT6, VW, Renault, etc. swing axle it's a great upgrade.
Since I have several Spit/GT donor cars here I am going to have to seriously look into this.

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 Post subject: Re: CC&AR Revisited
PostPosted: April 3, 2017, 3:37 am 
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Driven5 wrote:
Then again, there were also plenty of people who once professed these exact same sentiments about double wishbone suspensions...

Possibly (though I don't know of any such comments - the earliest UK race use of double wishbones that I can recall was the R-type MG Midget, which seems to have been universally regarded as an advance over the beam axle Q-type it replaced; racing primarily at Brooklands at the time, we English took our bumps seriously!).

One of the problems is that the use of complex geometrical linkages is increasingly rendered irrelevant: race cars don't need it, because suspension travel is so limited, and street car manufacturers can do a better job with active, reactive and interconnected suspension systems, without sacrificing the packaging space that you need for transverse linkages. I think that systems such as CC&AR are doomed to remain nothing more than curiosities... but they're fun to play with.

Never lose sight of the William Bushnell Stout/Colin Chapman dictum, though: 'Simplicate and Add Lightness'

RichardSIA wrote:
Isn't the RC car at the top of the thread a fixed length axle?


At the scale of a model racing car, there's probably enough play/endfloat in the driveshaft to avoid binding being such a problem.

The Torix Bennett system would give you camber compensation, but if you retained the swing axle as the lower linkage, you'd still have the inherent problem with high roll centre and jacking?


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 Post subject: Re: CC&AR Revisited
PostPosted: April 3, 2017, 3:50 am 
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It's the jacking effect I want to negate most.
"Z" bars sort of work, the "Swing Spring" sort of works, decambering sort of works.
Want to be able to use Spitfire/GT6 as single donors for some builds without having to replace the entire rear suspension.
Going to make some CAD* mock-up parts to play with.
If it binds up I will have my answer.

*Cardboard Aided Design, :lol:

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 Post subject: Re: CC&AR Revisited
PostPosted: April 6, 2017, 1:20 am 
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Any math or known samples available to help figure the ratios of the varied arms and fulcrum points?
Also seems it ought to be possible to use this to do inboard shocks at the same time?

Alas, the Torix Bennett system details are not coming up in web search.

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 Post subject: Re: CC&AR Revisited
PostPosted: April 6, 2017, 2:20 pm 
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Sam_68 wrote:
...R-type MG Midget...
The MG R-Type is actually a nearly perfect analogy to my point. It had a lot of potential, was praised by the racers who drove it, and saw some success on a small scale, but was obviously deemed not worth risking the added complexity and cost to develop by any other manufacturers relative to more 'conventional' designs that were actively winning bigger races at the higher levels. While the suspension may have been thought to be better than the Q-Type by those who were using it in competition, in reality its overall race performance did not result in appreciably better finishes than the the other cars it was competing against at the time. It would be numerous years later, before double wishbones on both ends of the car were developed to a point of providing enough demonstrable advantage to gain widespread acceptance. Maybe it would have been a different story if they had been allowed to fix the (known) flaws in the suspension design, but alas the entire program was scuttled before that could happen...At least, that's my understanding of it.

Don't get me wrong. I'm not saying that CC&AR is actually the next double wishbone suspension that (with enough development) will take the world by storm. Especially not with the electrical wizzardry going into high end suspensions these days. But I also don't think enough people have put enough effort into finding the limit of its potential to so easily be able to off-handedly dismiss its potential either. Without people interested in challenging convention, and not being afraid to fail in the process, the world would be a pretty boring place.

And in all fairness, I still not sure I'll be able to get to where I need to be with it either, to even try implementing on my car. As I've begun digging deeper into the geometric anti-roll (roll center) forces, it's often not a pretty picture, So even after finally finding a geometry that provides the desired combination of contact patch and anti-roll/jacking properties, you suddenly find that the 'roll center' movement kicks you square in the plums.

I previously acknowledged not being convinced by DAX/Walker noting the roll center as being at the intersection of the lower control arm lines of action. I'm now more convinced than ever that they're either wrong, or being intentionally misleading. Sure that may be 'close' in a static position, but it does not quite move accordingly. In fact, it appears it might actually move up as the suspension compresses and down as the suspension extends. Not exactly intuitive...Or desirable. Although, admittedly I've only eyeballed it on theirs, and its range of motion appears to possibly stay fairly constrained at least. However I have been able to do a more accurate analysis of my own 'best' geometry to this point, that would have also solved much of the packaging shortcomings, and I have found this same problem occurring.

So I'm going back to the drawing board...Again. I've already found some potential improvement, but the manual iterations are also rather slow going. Like you said, luckily it's fun to play with though. However, I may yet still ultimately shelve this idea, if I am not able to get any closer to a solution that passes muster on all fronts relatively soon.



RichardSIA wrote:
Any math or known samples available to help figure the ratios of the varied arms and fulcrum points?
Also seems it ought to be possible to use this to do inboard shocks at the same time?
Sorry, as you may have already read, I don't have any easy answers on ratios and fulcrum points yet. I did originally start with a design that integrated with an inboard suspension as well, but does also result in two rockers per side. I'm not sure how one would get the anti-jacking effect to work on a swing axle though. You need a mechanism that can translate the lateral force at one wheel into a vertical force at the other wheel. As it would seem to work in my head, I don't see how you could do so on an actual swing axle.

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 Post subject: Re: CC&AR Revisited
PostPosted: April 6, 2017, 3:22 pm 
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RichardSIA wrote:
Alas, the Torix Bennett system details are not coming up in web search.

Literally the first thing that comes up for me when I do a Google image search for 'Torix Bennett':

Image

The patent will be long expired, but I'm guessing you could still look it up from that patent number fairly easily.


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 Post subject: Re: CC&AR Revisited
PostPosted: April 6, 2017, 6:07 pm 
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RichardSIA wrote:
Isn't the RC car at the top of the thread a fixed length axle?


No. The plunge is at the inboard end.

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 Post subject: Re: CC&AR Revisited
PostPosted: April 19, 2017, 1:16 am 
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Driven5 wrote:
Sam_68 wrote:
The CC&AR is/was interesting, but is just one in a long line of dual roll centre/camber compensation ideas that go back to the Trebron and Fairthorpe TX systems of the 60's and 70's. They invariably add complication and cause as many problems as they solve. Actually, the Torix Bennett Fairthorpe was probably the simplest and most practical. Faced with the complexity of CC&AR, I'd probably go for a lightweight, properly located beam axle like the Lotus 58, which does almost the same job but with a lot less complication.
Yes, this would ultimately function very similarly to the Torix Bennett rear suspension...Although for all it's simplicity, I wonder just how' optimized' the geometry was actually capable of being...
So after some further investigation, it seems to me that not only is the Torrix Bennett solution the simplest means of implementing this type of system, but actually seems to be the best overall solution to date for what I am interested in accomplishing as well. I have to thank you for introducing me to this, as I had not heard of it previously. :cheers:

Unfortunately there is extremely little information available on it beyond that sketch and a few simplified descriptions. I have yet to even find a single photo of the actual completed rear suspension. Thankfully though, that sketch does still provide enough information to run with.

Fortunately, I also believe my chassis is already set up reasonably well to incorporate such a design, and may even reduce my build time...Juts as soon as I get around to re-starting my build. Like pretty much everything else, it will require making a few compromises in the process, like sliding the diff forward a couple inches to work acceptably with my uprights, but nothing outrageous as far as I can tell.


RichardSIA wrote:
Thinking mostly of Spitfiire and early GT6.

As an added bonus possibility, the Fairthorpe cars that used this suspension were apparently built on a modified GT6 chassis.

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