Inertial and Vibration Losses?

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MERuhl
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Re: Inertial and Vibration Losses?

Post by MERuhl »

Just fyi, I've decided to put off the Sorbothane experiment until next year. I'm going arsty with my Open Division car this year.
PwEngineer
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Re: Inertial and Vibration Losses?

Post by PwEngineer »

Hi all, thought about starting a new topic for this, but here goes anyway -

:?:

Does anyone know where the rule banning springs came from?

Can someone get ahold of Don Murphy to see if he started it?

What was the intended purpose?

Where did they think the springs would be used and for what purpose?

My daughter and I are finishing up her pw suspension study and thought that this info would work well into the background info. Who knows, it may even legitimize the wooden suspension idea.

I can see metal spring suspensions being banned for upping the skill level way over the abilities of cub scouts (some other construction techniques come pretty close to that as it is) but wooden ones? It's just carving and cutting right!??

:?:
Michael Lastufka
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MaxV
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Re: Inertial and Vibration Losses?

Post by MaxV »

Can someone get ahold of Don Murphy to see if he started it?
You can send Don an e-mail at:

PWDfounder@nogreenbananas.com
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MERuhl
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Re: Inertial and Vibration Losses?

Post by MERuhl »

PwEngineer wrote:Where did they think the springs would be used and for what purpose?
Seems likely to me that it was originally intended to prevent the use of springs for propulsion.
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TurtlePowered
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Re: Inertial and Vibration Losses?

Post by TurtlePowered »

PwEngineer wrote:Another Mike??

Glad to meet you. I can't chat long, but I'd like to know more about "Sorbothane". I'd do a web search, but I have "real" work to do!

I can't say much right now, but the suspension angle has possibilities for four wheelers. Give me a few days (weeks?) and I'll be happy to "spill the beans".

Likely a report will come out in the Pinewood Derby Times - it's my daughter's project. We've also got a "major" 5-factor study coming out. So make sure you subscribe. There'll be plenty to discuss then.
Are you reffering to MaxV's Pinewood Derby times??
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MaxV
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Re: Inertial and Vibration Losses?

Post by MaxV »

Are you reffering to MaxV's Pinewood Derby times??
Yes, that's the newsletter PWEngineer is referring to. Subscribe at:
www.maximum-velocity.com/subscribe.htm
ExtremePWD
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Re: Inertial and Vibration Losses?

Post by ExtremePWD »

I am intrigued by the body suspension idea as well as mounting the mass with different isolation medias. Many years ago I was a torsional vibration analyst and the same principles apply. In general, when the mass is high and the spring rate is low the mass can be fairly non-reactive to the input on the other end of the spring. Our pack and district rules state that the weights shall be passive. I would consider these design ideas as having active weights since their motion does not follow the motion of the rest of the car. I will need to get a ruling from our district guru. Our typical running environment is on very smooth tracks so it probably is not of that much value anyway. If we were running on rougher tracks and it was clear that the rules allowed it (or did not disallow it) I would certainly be running a version. I may start experimenting anyway for open class competitions. Keep in mind that a smooth track will reduce the benefits and if the benefits are small to begin with then they might be offset by poorer aerodynamics if the mass rides higher in the design.
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Jungle Jim
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Re: Inertial and Vibration Losses?

Post by Jungle Jim »

PwEngineer wrote:Hi
Does anyone know where the rule banning springs came from?

What was the intended purpose?

Where did they think the springs would be used and for what purpose?

I can see metal spring suspensions being banned for upping the skill level way over the abilities of cub scouts (some other construction techniques come pretty close to that as it is) but wooden ones? It's just carving and cutting right!??
Hello,
I believe the rule was originally put in to stop anyone from fitting a wound-coil type of spring to the wheels. This would give any car such fitted an obvious boost at the starting line. Subsequently, it has also kept any type of suspension system - other than the obvious rigid - off of the cars. Granted this would have to be tuned to operate positively, but it could be done.

Good luck to your daughter on her study.
Jungle Jim
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