43 replies to this topic

[MSwiss]

Yes. Launching seems "hit & miss" though... not everyone launches all the time. It seems more prevalent on the middle lanes. I "think" the bridge is sagging slightly; thus, causing the launching.

Is that the track that was private and in a shop.

 

Without me getting into my whole soft wall spiel, if it is the one I'm thinking of, that has the super wide shoulders, there would be room to probably put about an inch or more of padding.

[Bill from NH]

I think you're right. I believe it was previously Kyle Stokes' track located at his business(body shop?).

[MSwiss]

Yes, that's the one.

There was an LTD in this area that had the launch ramp deal going on, on the bridge.

The car would exit the track, but hit the raceway wall

Some guys refused to race on it, especially with Eurosport, because they thought it wasn't worth ruining their car.

A GT12 car got wedged in between the wall and a fire extinguisher so tightly, you couldn't remove it or the extinguisher, without unscewing the bracket.

[Tex]

Yes, this is Kyle's old track, with the wide shoulders on the outside of the turns.

 

I don't use a choke. I can't even spell choke.

[Uncle Fred]

Does R.L. stand for "Retro Launch"?.....................   Honestly, Rich makes as strong a chassis as I've ever seen.  I don't think that this kind of damage could be avoided after a solid hit like that.

[Howie Ursaner]

a good RP car , even a light one,will stay in the slot  pretty much no matter what if it is going fast enough for the high downforce body to keep it in. They are super punched. Your heavy car was not running like a RP should i suspect.

[Tex]

a good RP car , even a light one,will stay in the slot  pretty much no matter what if it is going fast enough for the high downforce body to keep it in. They are super punched. Your heavy car was not running like a RP should i suspect.

 

Well, no, my heavy RP was getting beat off the corners by Ken Stevens' light RP like I was tied to a tree. I wasn't having any particular launch problems but nor was Ken. I should also mention, though, that launching over that bridge is not unheard of. Besides being slight uphill then slight downhill(as one would expect of a bridge), the track also curves slightly once you exit the previous tight right-hander and before you get to the "donut"... essentially, it's shaped like a banana. So, combine uphill/downhill/banana... and you get some launches sometimes. Anyway, I decided to lighten my RP by hacking away at the brass, in an effort to try to keep up with Ken. Even lightened, my RP was still over 10g heavier than Kens RP... and it launched in just a couple laps. So, I'm pretty apprehensive about putting my new RP out there and punching it over the bridge. But, I gots ta try... otherwise, I'd be resigning myself to never being able to keep up with Ken.

[Uncle Fred]

Howie, take a look at the "Straight" on this track, it's really a 20 foot curve that you drive punched. 

[Bill from NH]

Ken was a racing buddy of mine 45 years ago when we both lived in eastern Massachusetts. I drove several of his Thorp-powered scratchbuilt cars.. He ran fast in those days too.

[MSwiss]

Tex,
Maybe try moving your body forward a bit to get more nose pressure.

[Tex]

Ken was a racing buddy of mine 45 years ago when we both lived in eastern Massachusetts. I drove several of his Thorp-powered scratchbuilt cars.. He ran fast in those days too.

 

I personally rank Ken as the top retro racer in Texas right now.

[Tex]

Tex,
Maybe try moving your body forward a bit to get more nose pressure.

 

I'll try that! I may just be able to finish my new RP for this coming Saturday. I expect to be mounting the body Thursday and painting it Friday. I'll mount it as far forward as I can. Thanks for the tip.

[Uncle Fred]

That's an old Wing Car technique. 

[Half Fast]

I was wondering why light cars were working on a flat track. Now I know the lighter cars are less likely to launch because the areo downforce keeps them pinned.

 

Cheers

[Tex]

I was wondering why light cars were working on a flat track. Now I know the lighter cars are less likely to launch because the areo downforce keeps them pinned.

 

Cheers

 

Yet mine launched only AFTER I lightened it. Go figure. lol

[Uncle Fred]

Speeds are not as high as the King so Aero is less effective. 

[tonyp]

Which body are you using? The Porsche has the most downforce in back. I'd also cut out the vents in the fenders and the one between the wheel wells in front.

[Rick Moore]

“Rick Moore would be an excellent guy to ask.”

 

I wondered why my ears were ringing…

 

“If ya ain't tearin' stuff up, ya ain't learnin'.”

 

Not sure about the first quote, but I have to whole-heartedly agree with Pablo on the second!   

 

And I ain’t no engineer either. So, from this point on, waders are optional…

 

But, what seems like millennium ago, back in the mid 90’s when I got back into slot cars I immediately went back to scratchbuilding (“You know you can’t race those…”), because that was what I enjoyed the most, typically sticking G-12’s in the things, with the “GTP” bodies of the day which had less down force than contemporary LMP’s (which I like to use now), and seeing what the heck would happen… Not always so good… I had a couple “parallelograms” result as well…

 

I sat down with a stack of paper and doodled out a series of diagrams trying to figure out the “lines of force” imparted on a chassis during impacts. Some rather brutal experience back in those days had shown the vast majority of severe impacts occurred at one front corner or the other, spreading those forces through the chassis from that point of impact. Square-on front end impacts seemed to be the next in frequency, but much rarer in actuality (usually one front corner gets there first). After that, side and rear end impacts were even less the worry…

 

So I concentrated on the front corners…

 

Then I had to visualize the forces that typically work on a running chassis… an exercise that continues to this day…

 

All the lines of force work at various angles to the typical longitudinal and lateral design and structural elements of the chassis. This was especially true when those forces were transferred to those rather nicely longitudinal parallel main rails I was still using at the time… Everything would load into them at angles that would easily knock them out of "square". Bummer.

 

I also had to consider the materials. While brass plate was strong, once it reached a certain force it would deform permanently; it also tended to impart any force applied to it in all directions. Steel wire was less rigid, but had a greater ability to return to its original configuration. Hmmmmm…

 

What I realized eventually was that “mass” does not guarantee “strength”. And “rigidity” definitely does not equal “strength”.

 

The question became, “If the vast majority of forces, both impact and running, that affect a chassis are NOT imparted in lines/directions that run longitudinally or laterally to the framing, why build the chassis with components running along those “rectangular” lines, and why not build the framing at angles?”

 

So I doodled up and built some extremely flimsy looking steel wire chassis frames, the now ancient 1202 and 1203, where no internal framing wires ran longitudinal or lateral (except at the chassis perimeter). Basically, everything was triangles or truncated triangles (trapezoids, kind of).

 

And I literally beat the living bejeezers out of those two chassis. But they never broke or went out of “square”. Eventually I added some dynamic brass pans in between the framing to make them more predictable (I hadn’t learned about wire frames “spring loading” yet…). And, despite some serious abuse, they are both still around and still usable. But…

 

Change comes hard, you know? I would still build “straight railed” frames. Years would pass before I finally gave up on them, and went back to what I’d learned on the 1202 and 1203 (i.e., the 1219-based chassis).

 

Now all these weird wired things I build use a lot of angled components. Yeah, they look flimsy, but they’ll take some major shots and typically survive.

 

In fact, I’ve only had one fail in the last six years or so, and it was an F1, with a more longitudinal structure, that took one full speed rider major crunching wall shot. Still “square” and usable, but the chassis movement isn’t as “fluid” as when originally built.

 

Case in point, my recent 1238-Cc2 build took a hard wall shot a few weeks ago. All it did was skew the left-front wing structure, the rest of the chassis “giving” to the impact force. Straightened out the wing with the trusty old needle nosed pliers, put it back on the track, and it ran as smooth and fast as it ever has.

 

So, yeah, I like ‘em light and flimsy… They just bounce nicer…

 

Wow! That was a whole lot of… to be nice, and not get a warning, let’s say… something or other, possibly bovine excrement... Anyway, that’s what I’ve learned over these years…

 

I also realize this is longer than anything Richard likes to read of mine, so all apologies. (Besides, I know you just skipped to the end…   )

 

Richard/Tex’s car hit left-front. And probably real close to being at a 45-degree angle. When you consider the solid mass of the front wing wires, their 90-degree relationship with the parallel longitudinal main rails, the static brass plate between the front of the main rails, and the 45-degree bracing wire running from the front wing to the main rail, all the impact force went straight into the forward aspect of the left main rail just behind the brass plate, the right main rail deforming a little more rearwards as the rear of the chassis continued forwards…

 

That and two bucks will get you a cup of coffee…

 

Have fun!

 

Rick / CMF3

[Tex]

I only skipped half of it, Rick; I actually read a lot more than usual. Don't get me wrong, when I DO read the whole thing, I enjoy it... I try to understand the whys and wherefores of what ye de..er, do. You never know when one o' those nuggets of wisdom/experience will bubble up into the thought stream when staring blankly at the jig, trying to figure out what to do. As fate would have it, my new RP is somewhat angular, though not in the CMF3 way of doing things. It'll wad up nicely as it is basically a one-rail-of-062-each-side chassis.

 

Tony, I think what I have is the Mirage. I'll have to check with Ron about the legality of cutting out those holes.