Pinewood Derby Season Approaching!

[94GTLaserRC]

This year, our church is separating the smaller kids (next month) from the older kids (March). The older kids have states if they win locally. The younger ones just have the local event, but Im gonna make my niece's car, so I can "practice" for my daughter's in March.

Here's what I have so far:

This is last year's state winner...This car blew everyone away.

This is my cut out from today, rough sanding and weighted/plugged.

The little cut out in the front is to add a piec of weight if need be at weigh-in. I will also cut a larger area like that towards the back.

Here, you can see that most of the weight is indeed in the back of the car.

In case youre wondering what the hole is, I beieve that it helps prevent minor vibrations from travelling through the vehicle.

Here is an Ebay auction...This guy has DOZENS of cars just like this that he sells all year long, many times for $100.

http://cgi.ebay.com/VERY-FAST-PINEW...6002399049QQcategoryZ2595QQrdZ1QQcmdZViewItem

I sort of combined the the styles of this car and the one in the first pic. This car should win locally, but I need it to slaughter every car by a lot to know if it can compete at states.


Ill keep you posted.
RC

 

[1105]

We just did a test in physics with a car going down a ramp with no weight and with weight... The times were very very very close to being the same.

But I guess if something is too light it'll need weight to get it moving fast? Hope you win first place. Going for a best in show again too or just worried about winning?

 

[94GTLaserRC]

We just did a test in physics with a car going down a ramp with no weight and with weight... The times were very very very close to being the same.

That's hard to believe...It's been proven in the races time and time again that 4.8-5.0 oz cars are the ones to win...And the higher up in the air at the start (back, top weight) the faster, like the one in the pic. One of my First in Show Cars last year weighed 5oz, but it was a "slab weight" which took up the whole chasis.. The car won 6th in spped Turns out that if the weight is evenly disributed the rotational inertial is low (ability to rotate-balances in the center). WIth a higher rot. init. (weight to one side, the car can pass easier through the part of the track where it goes from straight down to horizontal (when the car has to rotate throught the area) Hope that Makes senses.

But I guess if something is too light it'll need weight to get it moving fast? Hope you win first place. Going for a best in show again too or just worried about winning

I have 2 girls in the group that goes to States if you win locally in March... This one is for the younger kids....If we win with this car, I can tweek it for my daughter's race. I plan to enter one for speed, and one for design (although locally they both could still win in both categories).

Ill put a picture of the design for the design car...it will ROCK!! Im gonna shape the car like a '71 Mach 1, then use the parts on the Model Mach 1 car to glue into place on the wood ( lights, grill, etc)

Ill get pics up later.
Thanks
RC

 

[94GTLaserRC]

BTW...where do you get the air brushes to paint the way you see in the first pic?
RC

 

[94GTLaserRC]

OK....Car surface is finished, wheels are trimmed and installed. Paint is on sanded and reapplied. (Pearl Champagne) Ive been practicing with the airbrush and cutting stencils, and I was able to trace out the stencil that resembles the blue flame in the pic above. I also cut a number 55 stencil

The 55 will go in front, and flames behind the hole.

I will post pics when the car is completely finished, but for now, this is what I have:

 

[1105]

nice lookin car. looks very areodynamic. Should place pretty good in the races

 

[94GTLaserRC]

nice lookin car. looks very areodynamic. Should place pretty good in the races

Remember Zach, of all the factors:

Weight
Weight placement
polished axels
lubricated wheels
wheel alignment
wheel base length
car width, length,
aerodynamics,

aerodynamics is the LEAST important. According to several good sources I read, the speeds are not high enough, and the distance is too short for aerodynamics to be a factor.

Cant wait to get the flames and numbers airbrushed on there!

RC

 

[xr8d302]

My solution

 

[94GTLaserRC]

Not too bad of an idea, but all that stuff adds up to a little more than 5oz

RC

 

[94-302-vert]

What do the actual rules allow? Can you drill out the wheels to make them lighter?

The reason that the cars with more weight in the back of the car win is simply conservation of energy. The potnetial energy is converted into kinetic energy, by having the weight in the back the car has more potential energy at the start...

List the rules and let's see what we can come up with.. I know between myself and the other engineers and engineering students you can have quite the advantage...

 

[Ozz]

My solution

Paint it up like a ricer, JR!

 

[Nagash01WS6]

Zach, the acceleration due to gravity didnt change. The magnitude of the velocity (speed) did increase.

I have the spreadsheet on the laptop.

 

[94GTLaserRC]

What do the actual rules allow? Can you drill out the wheels to make them lighter?

The reason that the cars with more weight in the back of the car win is simply conservation of energy. The potnetial energy is converted into kinetic energy, by having the weight in the back the car has more potential energy at the start...

List the rules and let's see what we can come up with.. I know between myself and the other engineers and engineering students you can have quite the advantage...

I dont know if you read/saw the first few posts, where I show the car balancing in the center of gravity, which is obviously in the rear. Making the front thinner and drilling out that hole allowed me to stuff 3oz of weights in the back part of the car.

Basically the rules are:

1. 5oz limit.
2. there is a length and width limit.
3 have to use their block of wood, their wheels, and their axles.


You can shave parts, add parts, etc, so long as you conform to above.

Int the pic a few posts above, you can see how thin I shaved the front wheels. Not only does this allow for more weight in the back but also creates less friction. Also, my front left wheel rides about 2mm above the track....it NEVER even touches the track...again less friction.

THere are such things as "speed" axles, where the section that the wheels ride over are smaller that the rest of the shaft, so only a portion of the inner wheel well rides on the axle. Obviously we cant use that.

Got some pics coming.
RC

 

[94GTLaserRC]

OK,
Just finished airbrushing the numbers on.

Keep in mind that after an hour of practicing the other night, this is the FIRST time I have ever airbrushed anything. I even traced the image in the first post on wax paper used an exacto knife to cut it out, used some tack spray to stick it on and sprayed it..

You can tell a pro did NOT do it, but for my first time, Im quite

RC

 

[xr8d302]

Lookin nice man!

 

[Black95GTS]

My solution

You forgot the VTEC stickers and 3000 watt 18's in the back powered by a 150 watt amp.

Car looks mint as usual, nice job! Why 55?

adam

 

[94GTLaserRC]

.

Car looks mint as usual, nice job! Why 55?

adam

The car is for my niece.. Her brother plays intramural football, and that's his number.

RC

 

[urban96]

My solution

needs more carbon fiber and a body kit

 

[94GTLaserRC]

needs more carbon fiber and a body kit

 

[BlownFiveLiter]

needs more carbon fiber and an unpainted body kit done only in grey primer

fixed