Results!

[Cabrzama]

This is kinda long, but wanted to give you the results of my son's first race last night and also ask a couple questions.

My son finished 3rd out of about 20 cars. There were 8 heats. He took first in 6 of them, a close second (half a car length back) on one of them, and fourth (last) on another one. The one where he took second, he lost to the overall fourth place finisher and he actually beat that same car in later heat.

On the fourth place finish he started off strong--was right in the middle of the pack--and then his car hit a lip or something at the bottom of the hill just before the flat stretch and it jumped the track and it never finished.

It was heartbreaking (the track jumping), but I'm convinced my son's car was fastest among all the cars. In the individual heats he actually beat the first and second place winners and had he not finished fourth on the one heat, I think he would have won it all.

Now, I'm trying to figure out why it jumped because no one else had a car jump. I have video that I need to review, but I think it might be one of two things. (1) We raised one of the front wheels (I think this was one of our secret weapons), but I think we raised it too much. We raised it by about 1/2" instead of the recommended 1/16 to 1/8. (2) We failed to pound that same wheel/axle in to the same distance as the others--it stuck out about twice as far as the other wheels (didn't think it would be a big deal, but it may have been). Any thoughts on that?

Also, you may recall we used magnets with a few bolts and washers attached as the weights. This worked out really well in that we could add what we needed according to the race scale. And, nothing flew off, they shifted a little, but stayed intact. We had a few people say they liked that idea.

A couple of questions I now have:

1. Someone felt the biggest reason my son's car did so well was because I put the weights up high. They were located in the bed of his pick-up. I didn't router it out so they stood up as high as the top of the cab on the truck. Is it better to have weights low or high or does it matter?

2. My son's car seemed to have an extra kick on a few of the races he won that the others didn't. In other words, his car was in the middle of the pack going down the hill, then just past the part where the track goes flat, his would pull a full car length or two ahead of the others. Any ideas on why that might have been?

All in all, it was a great experience. My son was all smiles and even though he finished 3rd, I'm satisfied he had a very fast car.

In addition to the problem we experienced, we just need to work on the costmetics. His was average at best and their were some really creative and well-done finishes on some of the other boys' cars.

Hats off to everyone here who offered suggestions and advice--I'm confident you all made the difference for us. I plan to keep participating in this group--I have two sons that will be in it next year. God bless and thanks in advance for your responses!

[Darin McGrew]

My son finished 3rd out of about 20 cars.

Congratulations!

On the fourth place finish he started off strong--was right in the middle of the pack--and then his car hit a lip or something at the bottom of the hill just before the flat stretch and it jumped the track and it never finished.

Not that it helps, but I probably would have re-run that heat. If the car jumped the track a second time, then I would have let the results stand.

We raised one of the front wheels (I think this was one of our secret weapons), but I think we raised it too much. We raised it by about 1/2" instead of the recommended 1/16 to 1/8.

Yow! The center guide rail on most tracks is less than 1/2" high (often 1/4" or 3/8"). Was the bottom of the wheel below the top edge of the center guide rail on your track?

Even if it did (barely) straddle the center guide rail, it would be very susceptible to jumping the track at the slightest bump.

Someone felt the biggest reason my son's car did so well was because I put the weights up high.

Don't put too much faith in observations like this. Many key factors in a fast car are things that you can't see by just looking at the car.

My son's car seemed to have an extra kick on a few of the races he won that the others didn't. In other words, his car was in the middle of the pack going down the hill, then just past the part where the track goes flat, his would pull a full car length or two ahead of the others. Any ideas on why that might have been?

It sounds like your son's car had less friction slowing it down than the other cars. Maybe it had better lubrication and axle polishing, or maybe it tracked straighter. Or maybe the magnets holding the weight created a minor "suspension" effect, allowing the weights and wheels to move somewhat independently when the car hit bumps.

[Stan Pope]

On the fourth place finish he started off strong--was right in the middle of the pack--and then his car hit a lip or something at the bottom of the hill just before the flat stretch and it jumped the track and it never finished.

Now, I'm trying to figure out why it jumped because no one else had a car jump. I have video that I need to review, but I think it might be one of two things. (1) We raised one of the front wheels (I think this was one of our secret weapons), but I think we raised it too much. We raised it by about 1/2" instead of the recommended 1/16 to 1/8. (2) We failed to pound that same wheel/axle in to the same distance as the others--it stuck out about twice as far as the other wheels (didn't think it would be a big deal, but it may have been). Any thoughts on that?

Both too high and too much play hurt you. Actually, it isn't so much too much play as difference in play between front and back!

1. Someone felt the biggest reason my son's car did so well was because I put the weights up high. They were located in the bed of his pick-up. I didn't router it out so they stood up as high as the top of the cab on the truck. Is it better to have weights low or high or does it matter?

I posted pertinent comments on raised CM last night on the thread about "Losing speed on the flat...". Usually raised CM nets disadvantageous.

2. My son's car seemed to have an extra kick on a few of the races he won that the others didn't. In other words, his car was in the middle of the pack going down the hill, then just past the part where the track goes flat, his would pull a full car length or two ahead of the others. Any ideas on why that might have been?

What you saw was that your son's car slowed less drastically than the opponents. Possible factors: lower wheel/axle friction, less runout in the wheels, better alignment.

The rear weighting and raised front wheel should bring you off the slope at the front of the pack, unless the front wheel brushes the center rail early on.

All in all, it was a great experience. My son was all smiles and even though he finished 3rd, I'm satisfied he had a very fast car.

In addition to the problem we experienced, we just need to work on the costmetics. His was average at best and their were some really creative and well-done finishes on some of the other boys' cars.

Plenty of time to learn about top notch paint jobs ... Few boys that age can appreciate a fine finish, much less have patience to produce it!

It is a race. What are the most important components of doing well in a race? What role does "looking good" have? (Well, I guess it would be more important if you had finished "out of the money.")

Now, suppose he says, "Dad, will you show me how to make my car that shiney?" Then the iron is hot ... strike! Help him learn!

[Stan Pope]

Also, you may recall we used magnets with a few bolts and washers attached as the weights. This worked out really well in that we could add what we needed according to the race scale. And, nothing flew off, they shifted a little, but stayed intact. We had a few people say they liked that idea.

Most issues related to magnets were discussed earlier, but I'd like to revisit it briefly. Accepting that they are legal in your races, is their net effect good or bad?

Assumption: the magnetic field below the car is not significantly diminished.

You know that most tracks have ferrous materials scattered about the lanes, and not necessarily in nice symmetric patterns.

As the magnet approaches a screw or nail in the track, the magnet is attracted to it, and as it passes, the magnet is drawn back toward it.
There are two effects which partially offset each other.

First, the magnet (and, thus, the car) gets a slight acceleration and then a slight deceleration The net is that briefly the car gets a "bump up" in its speed before returning to it's prior speed. But, since the screws and nails are below the car, the magnet pulls the car toward the track. In effect the car "gets heavier." The result is that briefly, the force between axle and wheel increases, and with it the friction force to slow the car.

If there were a lot of nails and screws to be attracted, I'm pretty sure that the additional friction would dominate. But, I'm not so sure about what happens if there were fewer nails and screws, say every foot along the track.

I'm also concerned of the effect from asymmetrical distribution of nails and screws... would this have the effect of deflecting the car from its straight path down the track?

Thoughts, anyone?

[Cabrzama]

Interesting, indeed, my magnets were on top of the vehicle, but I see what you are saying if they are placed in close proximity to the track itself.

Would be good to hear if anyone has done any research on the affects of this.

[Stan Pope]

Interesting, indeed, my magnets were on top of the vehicle, but I see what you are saying if they are placed in close proximity to the track itself.

Okay, guys, refresh my memory, please! Force of magnetic attraction follows the inverse ________ law. Square? Doubling the distance between magnet and ferrous metal causes the attractive force to reduce by _______.