43 replies to this topic

[Tex]

One moment testing, the next...
 
LOL. That's the way it goes sometimes. Good thing I have my next RP on the building jig already. Rainy day here... there's a chance I can finish it today; if not, I may not get to race RP next Saturday.

[MSwiss]

Bummer.

Ridered into the wall?

[FVracer]

Richard, which turn? That is really whacked.

[Racer36]

My money says it does not fit in the jig again!

[Pablo]

Looks fine to me, Richard. Maybe I should slow down on the brandy

[Eddie Fleming]

just whack it with a hammer, and it will come back into square????

[Pablo]

I'll bet Tony P. would say "test it before you count it out - it make work even better that way"

[tonyp]

Lol yup.


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[Tex]

Richard, which turn? That is really whacked.

 

Launched going over the bridge, smacked the "donut" wall hard.

 

This car was formerly a King track car; I added the brass to help me learn to drive an RP on the DSC flat track. The car was very heavy(maybe 115g?) compared to Ken Stevens' car(86g?) and I was getting eaten up coming off the corners(not surprising). So, I lightened it up by cutting off a lot of the brass... got it down to 99.5g. R&D has now ceased on this chassis.  LOL   The RP I have on the jig is being built to be light also(relatively speaking). I'm a little apprehensive but I Ken is able to run light, so I figure I've got to try and run under 100g if I want to get in the game.

 

On a side note, I mused to myself why the car got damaged the way it did. I never had any formal engineering training but I do try to understand some of the hows and whys things are done on 1:1 race cars when I read about it or hear about it on TV. In my mind, this chassis isn't repairable and wouldn't have been able to be "competitive" any more had it happened in a race(might have been able to limp around as a moving obstacle and incur the ire of fellow racers.... something I'm not inclined to do). I think I know why and how it got damaged the way it did and there are ways to avoid/mitigate such damage. I think I've been presented with this lesson previously(maybe more than once)... obviously didn't learn my lesson or forgot the lesson. Let's compare notes... can anyone tell me WHY and HOW it got damaged the way it did("hit the wall hard" doesn't count... that's a given)? AND how could such damage be avoided/mitigated? I have my answer; what's yours?

[Pablo]

1. You have a lot of strong wires up front (bumper) that transferred, instead of absorbing, the energy rearward to the first weak point, which is where the rails cradle the front chunk.

2. Front chunk is not supported by enough rails - you have one of them split off from it's real job which was to support it, and it supported the front bumper instead. See #1.

3. Chunk needs to be longer IMO, at least 1"

4. I don't see any broken solder joints, you should be proud of that.

 

I ain't no engineer, either, but that's what I see. Rick Moore would be an excellent guy to ask.

 

If ya ain't tearin' stuff up, ya ain't learnin'

[Samiam]

Rich,

 

I have been told this is why they went to steel chassis in the last remaining brass and wire cars(Int-15). They just can't survive the crashes a Gp-12 motor can generate. 

 

The only way I can imagine adding strength without adding much more weight is to add 90 degree wire braces to the weak points. Also, jmo, the front bumper should not be so stiff. Two .055"s would work but would bend in a big wreck and absorb some of the impact.

 

Edit: See Pablo's post above.

[MSwiss]

I agree with Pablo.

 

Way too much stuff up front.

 

As far as how the car will run, after you tweak it back (semi)straight, we did it all time with wings, but of course, you have way more downforce.

 

I badly parallelogramed a chassis at the 99 Nat's warm up.

 

It was ballistically fast through the tough lead-on, on Black.

 

I went as far as trying to have multiple pin choices that would purposely cock the body over at an angle to simulate the same thing.

[MSwiss]

I have been told this is why they went to steel chassis in the last remaining brass and wire cars(Int-15). They just can't survive the crashes a Gp-12 motor can generate.

Not really.

 

GP.12 chassis became steel, because as production costs came down, which made it possible to meet the USRA mandated prices, manufacturers went to it  to cut down labor.and provide more consistent performance.

[Pablo]

“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.”  Archimedes

Archimedes being the crash force, the bumper rail assembly up front being the lever, the weak point at the chunk/rail spot being the fulcrum, and everything rearward being "the world".

 

I applaud you, Tex, for posting it. Without crashes, there would be no crash management. Thank goodness in slot cars nobody gets hurt

[tonyp]

I agree with Mike. Too much bumper up front. It probably hit on the corner and bent chassis. No bumper probably would have just tore up the body and bent the front axle instead of the main rails.


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[Tex]

You guys hit the nail on the head; I agree. In 1:1 racing, they learned to build in "crumple zones" and/or components that will absorb energy and break away under heavy impact. I've tried to build strong cars to be able to continue after a shunt, BUT.... by making the front TOO strong, the energy of the impact just got transferred to the weakest point rearward.

 

Of course, the RP on my building jig is ALSO built up just as strongly up front(sigh).  LOL  Under "normal" impacts(other cars generally), this has had the desired effect of being able to continue with a relatively intact car. But taking a wall shot proved to be too much.

 

Solution?

 

Don't launch.

 

(Now, where's that book that says how not to launch?)

[MSwiss]

Do other racers having launching problems there?

[Half Fast]

Does DSC no longer have a standard King track? I don't see one on their website.

 

 

Cheers

[Tex]

Do other racers having launching problems there?

 

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.

 

 

Does DSC no longer have a standard King track? I don't see one on their website.

 

 

Cheers

 

Nope, they sold their King track. I hear it is being setup in the Dallas suburb of Wylie, Texas.

[Uncle Fred]

It's straighter than the cars I run........

[Half Fast]

It looks like Retro Pro's would be a handful on the track!

 

Cheers

[Bill from NH]

Tex, you found the weak links. Strengthen them on the next build.

[Tex]

It looks like Retro Pro's would be a handful on the track!

 

Cheers

 

We're running under RETRO rules... Big Dog arm is as big as we can go. It's still a handful for this old-timer; I get to the next turn before my trigger finger is ready.  LOL

[Tex]

Tex, you found the weak links. Strengthen them on the next build.

 

I've been thinking(ouch, it hurts! and it's so much work!)... I'm not going to change my building philosophy. I'm going to build 'em strong enough to withstand T-boning other cars but I don't think I could make a competitive car if I built it to withstand a wall shot. I'll take my chances.

[Bill from NH]

Tex, when the accident happened, were you using a choke, or running straight up?  You don't have to change your building philosophy, Just bullet-proof it here & there a bit more. The front bumper change mentioned by Mike Swiss might be all you need.