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#1 scaleuser

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Posted 24 March 2020 - 03:14 PM

Simple question: why is a centerline hinge against the rules? Like it works too well? Can't use it. Not fair.

 

Did anyone ever build one? I have never seen or even heard of one. But I did miss the years from '69 to wing cars.

 

Is the statement a joke because it can't be done? Like "no zero mass axles"?


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#2 Jay Guard

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Posted 24 March 2020 - 03:38 PM

To the best of my knowledge a centerline hinge was never used on the scratch built chassis' in the 1966 to 1968 time frame. Which is the time period the modern IRRA cars are emulating, but not necessarily duplicating. In fact even hinges running in directions 90 degrees to each other weren't a feature on the inline cars of that time frame and only came about with the anglewinders of the late 60's. Note that there could be an exception or two built by someone somewhere to what I've said above but I believe that it is true to a great extent. 

 

BTW... A centerline hinge is indeed possible and was a feature that many of the late '90s and early 2000s Eurosport cars had, definitely not retro in the IRRA sense.


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#3 Cheater

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Posted 24 March 2020 - 04:08 PM

Simple question: why is a centerline hinge against the rules [in racing under IRRA rules]?


The primary reason is that the creators of the IRRA rules in 2007 sought to simplify chassis construction, and not to permit overly complex chassis designs with a multiplicity of movements and elements, with the idea being to lower the time needed to scratchbuild a chassis to run under that ruleset, and thereby to lower the barriers to participation.

Centerline hinge chassis were/are much more often used various forms in Europe and elsewhere, where they are commonly termed 'flexi-board' chassis.


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#4 Tim Neja

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Posted 24 March 2020 - 06:59 PM

Yeah the original idea was to suck people like ME into BUILDING chassis to race retro!! So they kept the rules as simple as possible, and true to the era-- so rookies could bend some wire and brass and go race!! And it worked-- nearly 12 years later -- I've built over 75 chassis of various kinds from F-1 to Can Am to Retro Coupe.  It's be a LOT of FUN--and thanks to people like Bryan Warmack and Steube, Dennis Samson, Tony P.  and other builders sharing their knowledge and techniques-- we've got a lot of different designs running and competing well together!! I hope more people will find the joy in racing something they build themselves. It's a very large part of the FUN!!  


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#5 Ramcatlarry

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Posted 24 March 2020 - 07:46 PM

I built a center hinge test mule from an (also) illegal Slick-7 inline kit and could not see any advantage on either flat or banked tracks.  Still take it out for a spin now and then.


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#6 scaleuser

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Posted 24 March 2020 - 08:09 PM

Thanks Jay, Greg and Tim

 

We were talking about chassis theory on another tread and it started me thinking about twist flex and how it needs to be damped. Indeed a centerline hinge would give that in spades.

 

My problem is that missed period where scratch building must have returned long enough to invent stupid fast. That and stamped steel remain but, if you want to scratch build, it's back to the past. No use retracing those middle ages. Even retro pro isn't very popular.

 

I'm fine with it. Just wondering since I knew it wasn't done in the golden era. 


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#7 CDavis7

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Posted 24 March 2020 - 08:14 PM

Its simply a rule set. And there are chassis designs which creatively skirt the rule to provide the effects of a loose center hinge. The most obvious examples being a kamo design, and my personal favorite being the jackal-pro which Ive built and use myself. IMHO, both the kamo and the j-pro use a center hinge but the tech directors have decided that they dont violate their definition of a hinge.

It comes down to how one defines a hinge. Does a hinge have to be freely rotating to be considered a hinge or is their such thing as a flex hinge, such as many RC planes use on alerons for instance. 🧐
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#8 MSwiss

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Posted 24 March 2020 - 08:37 PM

On the Kamo chassis, the center rail is soldered inside the tube.

 

And it obviously, also is, on Dom's chassis.

 

post-735-0-05806100-1538102924.jpg


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#9 CDavis7

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Posted 24 March 2020 - 08:40 PM

Mike- I know. Thats why I clarify that the definition of a hinge is the deciding factor. Its NBD. The rule enforcers have defined a hinge as freely rotating for our purposes but thats not necessarily the correct definition of a hinge

For instance, this product is a hinge and is solid

https://www.usplasti...bxoCQUkQAvD_BwE
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#10 MSwiss

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Posted 24 March 2020 - 08:49 PM

noun
noun: hinge; plural noun: hinges
a movable joint or mechanism on which a door, gate, or lid swings as it opens and closes or which connects linked objects.

 

A rail soldered on both ends is not a hinge.

 

Your "flex hinge, ailerons" comparison isn't applicable.

 

It flexes because the tip isn't connected to anything.

 

A center rail, only soldered on one end, would just be a skinny weight, that would probably just drag the track in the Bank, and upset the track owner.


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#11 CDavis7

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Posted 24 March 2020 - 08:49 PM

In any case, I love my j-pros from Doms kit so much that Im working on a third one. I dont make the rules, I just play by them.

Hopefully we can return to racing soon
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#12 Upfront slot cars

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Posted 25 March 2020 - 08:52 AM

Center hinges are a waste of time anyway. Look over the race reports from the start to now. Center hinge/tuning fork cars don't rule the roost. Bartos has built more winning chassis then anyone else. Take a look at his rail combos for the answer to what is consistent and simple.


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#13 boxerdog

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Posted 25 March 2020 - 04:40 PM

I think the original idea was (?) to make the chassis stiffer front-to-rear while not increasing the torsional stiffness. The Z-bar idea looked like it was another way of doing something similar. 

 

In real cars, that might equate to ride stiffness vs. roll stiffness. Or running very soft springs and giant sway bars. 

 

I have no idea if it really works or not as applied to slot cars, although Jim F and I tried to make one setup into a kind of chassis tuning device. I don't think we ever reached a conclusion other than it was a lot of work and maybe there were easier ways to do the same thing. But I don't think it can be called a hinge in any event. 

 

JMO. 


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#14 CDavis7

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Posted 25 March 2020 - 04:48 PM

Center hinges are a waste of time anyway. Look over the race reports from the start to now. Center hinge/tuning fork cars don't rule the roost. Bartos has built more winning chassis then anyone else. Take a look at his rail combos for the answer to what is consistent and simple.


Welp, look at the race reports in NERR and let me know what you find. That's the primary series in which I race.


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#15 Ramcatlarry

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Posted 25 March 2020 - 06:36 PM

Slot cars are a bit small to install proper shock absorbers.  Harmonic vibrations can be dampened with tape and combining brass and steel rails as well as the amount that they are soldered together.

 

I see the center hinge as focusing the direction of motion as well as helping to prevent high bank CG forces.  The tuning fork helps a lot with the CG effect as well as give a secondary spring rate if the fork and socket are loose enough to get a bit of float.

 

Most Eurosport and wing cars no longer use a hinge anymore, a past design fad.


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#16 Cheater

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Posted 25 March 2020 - 07:32 PM

The center hinge is a method to increase or control beam stiffness of a chassis, i.e. the longitudinal flexibility of a chassis between the axles, without increasing the torsional flexibility of that chassis.

 

Pushing downward on the midle of a chassis while it's sitting on a tech block demonstrates the level of beam stiffness it has. Holding a chassis in your hands, with the front axle in one hand and the rear axle in the other and then twisting demonstrates its torsional flexibility.

 

The longer the center hinge, the more beam stiffness a chassis will have.


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#17 Don Weaver

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Posted 26 March 2020 - 07:04 AM

Greg,

 

Seems to me the longer the center hinge the less the beam and torsional stiffness.  Or am I   :crazy: ?

 

Don


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#18 Mbloes

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Posted 26 March 2020 - 07:46 AM

Most Eurosport and wing cars no longer use a hinge anymore, a past design fad.

 
I think the reasons that it no longer works in Eurosport are (unfortunately, to me):

  • No more front wheels
  • Bodies became more focused on aerodynamics, rather than scale.

So 1/24 ES cars (d)evolved to become more like wing cars.
 
I believe that 1/32 ES still use it. Maybe it has to do with size/weight as 1/32 cars are still full pan while 1/24 cars are just perimeter now.


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#19 Cheater

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Posted 26 March 2020 - 09:07 AM

Seems to me the longer the center hinge the less the beam and torsional stiffness.  Or am I   :crazy: ?


Think of this hypotetical test, Don.

Take a piece of .032" brass strip an inch wide and five inches long. Fully solder a one-inch piece of .063" piano wire centered on the both the width and length.

Take another piece of .032" brass strip the same size and solder a four-inch long piece of the same piano wire also centered on the width and length of the strip.

Support each piece of strip close to the ends and then push downward at the center of each piece of piano wire.

I'm pretty sure you'll find that the strip with the longer 'reinforcement' will deflect less under the same amount of force.


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#20 Don Weaver

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Posted 26 March 2020 - 02:28 PM

Didn't know center hinges were soldered on a piece of 1" brass.  I was thinking of just a piece of wire soldered solid at one end and slipped into a tube at the other.  Push down on a 1" length and a 4" length and the 4" length will bend much easier.

 

Never raced or built Eurosports...

 

Don


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#21 Cheater

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Posted 26 March 2020 - 03:04 PM

Considering just the beam stiffness in the longitudinal direction, Don, whether the wire is soldered solid or can rotate makes no difference.

 

Push down on a 1" length and a 4" length and the 4" length will bend much easier.

 

The wire by itself, yes. But the 'chassis' (the combination of the brass strip with the wire soldered to it) will not bend easier with the four-inch wire than with the one-inch wire.


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#22 MSwiss

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Posted 26 March 2020 - 03:28 PM

I think the reasons that it no longer works in Eurosport are (unfortunately, to me):

  • No more front wheels
  • Bodies became more focused on aerodynamics, rather than scale.
So 1/24 ES cars (d)evolved to become more like wing cars.
 
I believe that 1/32 ES still use it. Maybe it has to do with size/weight as 1/32 cars are still full pan while 1/24 cars are just perimeter now.

 

Yes, in both 1/32 full fender and F1 cars.

As far as torsional stiffness, their only function in those cars is to allow the chassis to rotate in the middle.

I'm 99% sure they don't use the length or thickness of the hinge pin to tune the car.

As far as the original post, when I saw it, I thought it was 2009 again.

I thought the follow up question/comment was going to be "Youzz guys should have to use thumb controllers," or "Youzz guys should have to run orange tires." LOL.


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#23 Mbloes

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Posted 26 March 2020 - 03:53 PM

I'm 99% sure they don't use the length or thickness of the hinge pin to tune the car.

 
Yeah, you are right here.
 
The ES chassis these days are so completely designed that they really don't allow any leeway for alternative assembly options.
 
And then, since I posted that, I went hunting for the latest in ES designs. This is Dubick's latest 1/32. It has the center hinge, but the rest of the movement engineered into the chassis is mindblowing.  It was hard for me to follow all the rails.
 
chassis.jpg


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#24 Don Weaver

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Posted 26 March 2020 - 04:18 PM

Considering just the beam stiffness in the longitudinal direction, Don, whether the wire is soldered solid or can rotate makes no difference.
 
... (the combination of the brass strip with the wire soldered to it)...


Like I said, I didn't know that center line hinges were made with brass strip; thought it was just a single piece of wire. :wacko2:


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Don Weaver

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#25 SpeedyNH

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Posted 26 March 2020 - 10:34 PM

That chassis look like a cross between a Slick 7 and a Mossetti.


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