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Pinewood Derby- Cub Scouts

tsi_tom

By tsi_tom,
in Just plain ol' B.S.

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Dred_85.5_TSI Newbie

Dred_85.5_TSI

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^Actually, yes. If I remember right there are rules about maximum and minimum weight but not balanced weight. I built a few back when I was in cub scouts.

Mostly it is about aerodynamics, polishing the metal axels so the drag is minimized, a little dry graphite lube helps. Focus on making the car as aerodynamic as possible. sand the wood as smooth as you can, wetsanding the paint may gain some advantage.

 

http://boyslife.org/hobbies-projects/projects/2952/speed-secrets/

http://entertainment.howstuffworks.com/question169.htm

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My kids just raced theirs this weekend. I make them aerodymanic, wedged almost. My daughter got 3rd place. She kept running 1st place consistently on her division. Then they placed all the 1st place winners against each other. I wasn't there, so I didn't get to do the usual stuff like lube the wheels.

 

I'm on my second batch of kids racing the pine derby cars, my oldest now 19 and 17 raced for years. So come to think of it, I've been helping my kids since 2001. I've had luck with od shapes, not always the most aerodynamic cars have won. Too much weight up front is bad as well.

 

This last race, my daughters car had a "My Little Pony" crazy glued on top, the car was all glitter with her initial patterned up front. It was fast. But mechanical problems did occur, the pony fell off from all the vibration from the track.

 

Most of all, have fun with it. Let the kids have fun with it. They will remember that for the rest of their lives. My oldest always remembers her favorite derby cars and they were not necessarily winners but one that she had fun with.

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lmwii Newbie

lmwii

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My dad used a dremel to create a reservoir for graphite over each set of wheels with tiny tubes that came out over each axle so as to provide a tiny flw of graphite to the wheels as the car rolled down the track. I won my district a year or two and placed the other year or two I ran.
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importwarrior Newbie

importwarrior

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http://www.derbycham...CFUOK4AodUgIAEQ

 

check that site out.

 

Thunderbolt Speed Axles

note the cut down area where the wheels ride on...

fill with dry graphite lube

 

http://a248.e.akamai.net/origin-cdn.volusion.com/kvffr.teave/v/vspfiles/photos/610-2T.jpg

 

Rocket Speed Axles

 

http://a248.e.akamai.net/origin-cdn.volusion.com/kvffr.teave/v/vspfiles/photos/615-2T.jpg

 

 

Wheels!!!

Pro-RSX Racing Wheels By Derby Worx

less rotating mass less to get them rolling

 

http://a248.e.akamai.net/origin-cdn.volusion.com/kvffr.teave/v/vspfiles/photos/596-2T.jpg

Edited by importwarrior
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If they don't have any rules about using fancy stuff like those axles, than go for it.

 

Where my kids compete, they caught on to all that stuff. They only allow the use of the pine, axles and wheels they provide in the kit. Some dads in years past would buy precut pine cars with fancy wheel. They put a stop to it. The point is for the kids to have fun making the cars and no unfair advantage over the others.

 

 

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jszucs Newbie

jszucs

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Yeah even back when I did it they had rules on the axels, wheels ECT so check before you buy it. in general the wedge shape works best. Weight more twords the front (depending on what type of release your track has this helps) If you can, running the wheels slighly cambered so it's rolling on the inside edge only can help but they must be perfectly aligned for this.

 

Polish polish and polish the axels, Then polish them again.

 

The dry graphite is allowed but most have rules you can't put in onboard, and it can't be falling off / out of.

 

For paint spay it with rattle can and bake it low heat in oven for super shiney flat finish.

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jszucs Newbie

jszucs

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O another "advantage" thing you can do that inside the rules. But this depends on the track you have to run on. If you have one with a single bar that sticks up though the track in each lane, you can curve the nose of the car WAY up so that as the bar is lowered your car gets an advantage of leaving just a touch earlier.
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Richie_Rich Newbie

Richie_Rich

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I've seen a couple others say to put the weight in the front.

I'll have to disagree with that.

Here's why:

What propels your car is the force of gravity.

The longer you can have gravity acting on the car down the sloping part of the track, the better.

Putting the weight in the back will result in more time the mass is being acted upon, so acceleration will last longer.

 

Here in St. Louis, we have a lot of kid's parents that work for Boeing.

Believe me, the competition is unreal. There are stories of parents taking the cars in and putting them in a wind tunnel.

Those stories were told by other parent Boeing employees complaining about the ones that had access to one.

 

Polishing the nails is done by almost everyone.

I like the graphite grooves. You may be able to do that your self with a drill and some sort of cutter.

 

Polyurethane the car with several coats then polish and wax it.

 

You will learn a lot your first year.

 

I think we still have a couple cars.

Our first one, we put a Santa Claus standing in the back and couple reindeer in the front.

We won one of the prizes for most interesting.

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jszucs Newbie

jszucs

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I had a good friend who's dad worked for NASA and he did run his car in the tunnel, and water with dye tank. Best is wedge shape, and weight in the front. I know what your saying about it acting longer, but they already seem to hit terminal (do to friction I assume) by the time there down the hill. Ive tried front, middle, and back, and front has always worked out the best. Think about it more like a roller coaster going over the first hill. If your in the very front (you could have a ton of weight up there) but the weight in the back is still holding you until it comes over the top. Putting the weight in front helps the weight over the top first. It's all about the first few seconds, rules prohibit anything that will make you go fast enough to really make up any of that ground afterwards. Do make sure that weight is 100% centered L to R though. That makes a HUGE diffrence.

 

Ive even tried holes drilled straight though the car, with chamfered holes up front. Most advantage is designing for early release but depends on track and release mec used.

 

On a related note... do they still do the regatta races? That was allot of fun to.

Edited by jszucs
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I usually have the weight set up towards the middle of the car. I do wedge shapes most often. I've done the weight up front and out back and it creates other problems. Too far back on wedge shape car causes the front wheels to lift as the car is coming down the hill and reaching the flat end zone. I've cars come off the track cuz of that. Too much forward and it makes the rear bouncy and that kills speed and time.
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jszucs Newbie

jszucs

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^ agreed. I have had the same exact problems going to extrem forward. It's a reall ballancing act, and with no practice allowed (or atleast that was the way it was for me) you can build your own test track but it's never the same. We tested with a length of gutter and it worked well.
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