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Tips, Tricks and Hints
In this section we'll share tips, tricks, and hints that we learn along the journey toward building a great-performing Pinewood Derby race car! All tips will be presented to be understood by the boys building the cars, so don't expect any physics lessons here!
TIP: Run the maximum weight allowed.
The Pinewood Derby track is a downhill that transitions to a flat area toward the finish line. The only thing that will propel the car across that flat area is the amount of energy that can be built up in the downhill area. In other words, the faster your car is going at the bottom of the hill, the more likely it is to do well across the flat area. In scientific terms, your car has potential energy that is converted to kinetic energy as it races down the hill. That kinetic energy is what will take your car to the finish line!
The limit for cars that scouts build is 5 ounces. Your entry should be as close to that as possible without going over.
TRICK: Be ready to adjust your weight
Build your car so you can add or subtract weight easily. I use a set of wood screws. It is possible for cars to absorb moisture if it's humid. If the car is over by a little, take out a screw or two. If it's a little light, add a couple of screws. If you prefer, build it a little light and bring weight to add. Having it close and using weight tape sold for balancing ceiling fans would be a good plan. It's easier to add weight than it is to remove it.
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TIP: Your enemy is friction. Fight the friction monster!
Friction will slow your car. It's like the brakes on your bicycle or in the car. When you apply the brakes, you create friction and that slows you down. You don't want anything to slow down your Pinewood Derby car!
Where is friction? Anywhere a moving surface contacts a non-moving surface. That means if your wheels touch the car body, there is friction. Even where your wheels touch the axles (nails), there will be friction.
Apply lubrication to any point of friction to lessen its ability to slow your car.
TRICK: Lubricate the body!
Take a bit of lubricant and rub it into the area of your car body around the axle hole. This way when the wheel rubs the body, it won't be like putting on the brakes!
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TIP: Alignment for straight running
Alignment of your wheels is important. If your car is constantly trying to turn a corner, it will drag on the center rail of the track slowing it down.
TRICK: Check your alignment
One way to test alignment of your wheels is to roll the car on a hard, flat surface. Mom may not like you rolling your car on her countertop, so look for someplace else. The best thing to use is a sheet of glass with a line drawn on it with a marker. Tilt the glass slightly and let the car roll down the glass to see if it rolls straight or turns. If it turns, you can bend the nails slightly to get things rolling straight.
HINT: Polish your axles
The nails that come with the Pinewood Derby kit aren't perfect. There are edges and rough areas that will cut into your wheels. Take a file or sandpaper and smooth these areas out. Keep polishing them until they shine. Remember, you only need to do the area by the nail head that the wheel will spin on, not the entire nail.
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Participation
** You do NOT have to be a Cub Scout to race our Pack #247 Pinewood Derby! **
There are several classes for non-scouts to participate in and join in on the fun. We hope you'll participate and think about joining the scouting program as we do fun things like this all year!!
*** Cars can be raced by proxy, so you don't have to be present to race! ***
Let's face it. We all have busy schedules and we all have things come up at the last second. If you can't make the event, don't make your child miss out! Get the entry to a scout leader or bring it the morning of the event for technical inspection and impounding and we will race your car for you!
Learning while doing!
The Cub Scout Pinewood Derby presents an opportunity to learn skills such as wood working and is a great opportunity to learn about physics while building a car for the big race. The event is a time for the entire Pack to come together to race their cars and cheer for their fellow racers!
The specifics, rules, and classes are listed in separate sections below. This event is open to all Cub Scouts (Tiger, Wolf, Bear, Webelos, and Arrow of Light), siblings, parents, and leaders of Pack 247.
Maybe we can even get some former Cub Scouts that are now Boy Scouts to come and race again!
Please read on to see what classes will be run and what there is to look forward to!
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FAQ - Frequently Asked Questions
Here are questions we've come across. The answers are specific to Pack 247 rules.
Question: What do I use to weight the car?
Answer: Before getting into this, lets discuss safety. We should not use substances like mercury or bullets as a source of weight. Lead is dangerous as well. I highly suggest you not use it; however, if you decide to please be careful and don't handle it without disposable gloves and wash afterward. CUT lead, never sand it!!
Just about anything can be used to weight the car to get it to 5 ounces. Wheel weights for automotive tires are used quite often (these are usually lead, so be careful). Coins work, as do washers, fishing weights (sometimes lead), lead wire, and metals like tungsten. There are BSA-approved weights that work really well too. Some are plates that screw to the car and some are in other shapes. Whatever the shape, the weights must be secure.
Q: Where do I put the weight?
A: The weight can be placed anywhere on or in the vehicle. Just remember that anything attached to the car must be within the limits of height, length, and width.
Be concerned with the center of mass (COM). This is where the car would balance if you set it on the tip of a pencil. There are several thoughts: front, middle, rear, and to the side.
Side-weighting: There are thoughts that adding weight to one side or the other (front, middle, or rear) can make the car turn slightly. If it turns ever so slightly, then it will be more stable as it goes down the track because it'll gently ride the center of the track instead of going back and forth.
Front-weighting: The thought here is that having the COM in the front will help pull the car down the hill for a faster run.
Mid-weighting: Putting the weight so the COM is nearer to the center of the car will make it run with greater stability in the flat section. This can be accomplished by placing weight in the center, or by placing weight in the front and the rear - kinda like balancing a see-saw. Some like to do this to keep all wheels on the track.
Rear-weighting: The thinking for this is that since we're trying to get the car rolling as fast as possible down a hill, the longer the hill the faster the car will be going at the bottom. Since the length of the hill is fixed, the only way to get an advantage would be to move the car's COM as far up the hill as possible. That would mean placing it toward the rear of the vehicle.
Q: The rule is for 7 inches. Can the car be shorter than 7 inches?
A: Yes. The length rule is the MAXIMUM. The only thing that limits how short the car will be is the axle position - assuming you're in a class that doesn't allow altered wheelbases.
Q: My car weighs 5.002 ounces. Can I race it?
A: No. There has to be a cutoff somewhere, so 5.000 is the limit. If 5.002 were allowed to slip through because it's only .002 oz, then why not allow 5.003 since that's only .001 oz more?
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