Actual length of a 40 foot Piantedosi Freedom track

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PWD
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Actual length of a 40 foot Piantedosi Freedom track

Post by PWD » Wed Jan 24, 2007 10:23 am

I need the actual length of pin to typical finish spot on a freedom track. This would be the spot where you put the sensor for the finish.

Thanks for the help in advance!



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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by PWD » Sat Jan 27, 2007 8:04 am

I received an email back from Gary Piantedosi. It is 37' 6" if anyone is curious. So it is actually 6" longer than a 42' BestTrack



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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by Mr. Slick » Sat Jan 27, 2007 11:28 pm

So, at .001 second per 1/8th inch, on aluminum, that would be an extra .048 seconds! :)


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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by PWD » Sun Jan 28, 2007 3:51 pm

Our experience is that it has not worked out that way. I guess it is because of the difference in shape of the track but we are always faster on the Pianadosi over the BestTrack.

This is even though the Pianadosi is longer. This has been true on multiple BestTracks.



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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by SuperDave » Sun Jan 28, 2007 5:37 pm

This is not exactly a reply to length but rather to the concept of speed. It's a human tendency to measure the things we can rather than the things we should. Think, road speed (easy to measure) rather than driver skill, fatigue, road condition, etc. (hard to measure but arguably more important.)

In the Pinewood Derby world, we seem obsessed with overall time from start to finish (easy to measure) but I would argue that peak speed is far more important (and all but impossible to measure) and track dependent. A car that will track well and stay in the lane at moderate speeds can easily fly or wobble itself to death at faster speeds. Thus I'm guessing that a track that's a flat sloping ramp from start to finish would be easier for a car to handle than a track that fell to the floor in say 1 or 2 feet and then had a flat run out. Just food for thought.

Further thought. In a center guided (wood) track, the guide acts as a spoiler and reduces the tendency of an aerodynamic (wing shaped) car with a light front end from lifting off. Edge guided (plastic) and center-guided aluminum (the guide isn't solid) do not have the spoiler, so COG could be more critical. I've seen a car that had a huge vertical cutout in the middle to defeat the 'lift' problem.


(Note: the author is a designer and vendor of tracks, timers and software. Comments by him or to him should take that into account as appropriate.)

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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by BigDozer66 » Mon Apr 16, 2007 9:33 pm

I forgot to measure mine but it should be the same as yours. :D

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Re: Actual length of a 40 foot Piantedosi Freedom track

Post by SlartyBartFast » Tue Apr 17, 2007 9:08 am

SuperDave wrote:This is not exactly a reply to length but rather to the concept of speed. It's a human tendency to measure the things we can rather than the things we should. Think, road speed (easy to measure) rather than driver skill, fatigue, road condition, etc. (hard to measure but arguably more important.)
Not wanting to get political, but in the real world speed has some ultimate consequences that are dictated by the laws of physics. There are legitimate safety parameters that are controlled by speed. Limiting speed decreases the amount of possible damage and risk in the event of an incident, and increases minimum reaction times ensuring the average driver has sufficient reaction time before a possible problem.
Some jurisdictions DO adjust sped limit based on time of day or road condition. The German Autobahn is a great example. And how do they regulate based on road conditions? Lowered SPEED limits.
As your state transportation department for the forms to request a speed restriction review. You’ll find that while there are perhaps only a few standard speed limits, which one applies to a road depends on it’s condition, expected use, size, number of lanes, shoulders, and so forth.
And just because you might be a “better” driver, doesn’t mean everyone else is better than average and can deal with the situations that “better than average” drivers cause.
Then of course it is undeniable that reduced speed lowers fuel consumption.
Any more discussion along these lines belongs in an off-topic thread.
SuperDave wrote:In the Pinewood Derby world, we seem obsessed with overall time from start to finish (easy to measure) but I would argue that peak speed is far more important (and all but impossible to measure) and track dependent. A car that will track well and stay in the lane at moderate speeds can easily fly or wobble itself to death at faster speeds. Thus I'm guessing that a track that's a flat sloping ramp from start to finish would be easier for a car to handle than a track that fell to the floor in say 1 or 2 feet and then had a flat run out. Just food for thought.
Stability at top speed certainly affects the car. But what important part of the race does that stability affect? Start to Finish timing. The measured obsession is end to end time. Has to be. That’s what wins or loses the race.
But, the techniques to get better times are all to do with stability. Alignment, weight placement, riding the rail, etc.
Personally, knowing that a car has the highest top speed is irrelevant. Why measure it? It’s a cute piece of trivia for real racing, but it’s the car across the finish first that wins. Even in drag racing.
It may be of interest to lighten an unstable car (and thus reduce its top speed) to see if the car becomes stable and gets better race times.
Here’s another observation: The theoretical top speed is the same regardless of track profile if the drop between start and finish is the same. It’s the accelerations that are more brutal on a steep incline and fast change to flat.
SuperDave wrote:Further thought. In a center guided (wood) track, the guide acts as a spoiler and reduces the tendency of an aerodynamic (wing shaped) car with a light front end from lifting off. Edge guided (plastic) and center-guided aluminum (the guide isn't solid) do not have the spoiler, so COG could be more critical. I've seen a car that had a huge vertical cutout in the middle to defeat the 'lift' problem.
How much does lift affect PWD cars? Really?
If it really is an issue, then adding a spoiler or a design that creates some front end downforce is what’s needed. Not a huge cutout.
Could test the theories in that wind tunnel design that was on DT recently. But, IMO, aerodynamics is the probably the last thing to concern a PWD builder. Discussion about the wind tunnel seemed to back up my opinion in terms of drag. If there isn’t a significant amount of drag, it’s doubtful you’ll have measurable amounts of lift.
The lift seen in PWD cars is undoubtedly due to guide-wheel contact and angular accelerations and momentum as the car transitions from slope to flat. As the car is going through the curve, it is rotating with its nose rising and tail falling. That rotation and angular momentum is counter-acted by gravity as the curve lessens and the car moves to the flat. So, no matter the design, the front end will first become heavy as the car enters the transition and then lighten as the car exits the transition. If the momentum is too high, the front end will lift. If the CG is badly placed, it may then contribute to the car popping a wheelie.
Once the car has reached the bottom of the slope (maximum speed) and completed the transition (maximum accelerations), it's all about how well the car will maintain speed as it slows towards the finish line.



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