New builder needing help

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
Speedster
Pine Head Legend
Pine Head Legend
Posts: 1912
Joined: Sat Feb 18, 2012 2:48 pm
Location: Toledo, Ohio

Re: New builder needing help

Post by Speedster » Fri Dec 13, 2019 6:39 am

Welcome to "TOP FUEL DRAGSTER" competition.
While I'm not a fan of the Design category, this is rediculous. Do adults put the cars on the track so no one knows whose car it is? I'm going to take a guess and say these are not going to be the rules. Are they not going to allow "light sanding of the wheels"? You are educating me. I did not know scout shops sold pre-cut cars.

Don't count on Luck. There is no such thing. Yes, a slim wedge shaped car can be made to go really, really, Fast. We start with a wedge that weighs 37 grams. This allows us to get a 3/4" CoG in front of the rear axle slot. The 4 on the Ground rule might just end up being an advantage for you. We need to know the rules.

It's Dec. 14th. today. I decided to build another car that is strictly a wedge. It is a block from Hodges Hobby House, Item H 57, Slim stock slotted wheelbase, weighs 49 grams. 2 ounce behind rear axle slot, 1 ounce in front of rear axle slot. Stock BSA wheels and axles. Total weight 142 grams. That's close enough for Government work. CoG one inch in front of rear axle slot. Weight on front is 30 grams which is a bit over one ounce. (28.4 grams in an ounce.)

I also have a car cut to 5/16" and weighted with tungsten. CoG is 3/4" in front of rear axle slot. 3 wheel rail rider. Weight on front is 22.6 grams. This particular car turned a faster time on the Commodore Perry District 35' Best track then any car that raced in 2018.

I know you're after speed. I hope my experience, and the experience of others on Derbytalk, will guide you.



Singledad2019
Apprentice
Apprentice
Posts: 15
Joined: Mon Nov 18, 2019 3:41 pm
Location: Milwaukee, Wi

Re: New builder needing help

Post by Singledad2019 » Sun Dec 15, 2019 12:05 pm

I'm starting to see it is all about the axles and wheels. I took them off to paint it. Now, having issue putting them back on where they where. I was going to put them in the drill to clean them up, and then look into some wheels. The wheels can't have any off, because they check with a microgramer.



Speedster
Pine Head Legend
Pine Head Legend
Posts: 1912
Joined: Sat Feb 18, 2012 2:48 pm
Location: Toledo, Ohio

Re: New builder needing help

Post by Speedster » Sun Dec 15, 2019 2:25 pm

Be Patient. Everyone will tell you it isn't all about any one or two things and that's very true. Each thing you do is very important. Let's talk about wheels first. There are "Preferred" numbers of wheels and the vendors probably have all of them. I always bought #8 from Maximum Velocity. You were able to choose your number. I know Maximum Velocity is now owned by Derby Evolution but I'm sure there is still a way to get a set of preferred numbered wheels. They will usually be .003 or less out of round. If you find the rules allow "light sanding" then we can do something else which will be better. The wheel bores should be polished with Novus 2 and an extra fluffy pipe cleaner or with a polish sold by the vendors for this purpose. There are other things available to hold the polish and they work well but for now let's stick with one thing.

Let's talk about the nail. I'm going to say something that you probably will not hear from anyone else.
THE NAIL DOES NOT TURN. The nail comes with a shiny Zinc coating on it. The only casting marks I would remove are the 2 that are under the head. File them off using a light touch. Don't put them in a drill and grind them off and do any damage to the underside of the head of the nail. I don't do anything with the casting marks on the shaft. If they bother you, you can mark the head of the nail with a sharpy and you can install the wheel where the wheel will not touch the casting marks. You can buy BSA nails that have been prepped. If you are allowed to use the nail Made in China, use them.

When you have the wheels prepped, let's talk about installing them. Installing them is going to be a challenge and we need to know from the rules what we can do. Many of the nails are not straight. If we can find bent nails, no matter how little they are bent, we can use them to your advantage. All we need is to find them bent enough so we can get the rears to migrate to the axle heads and stay there and do what we need to do with the dominant front wheel. Yes, I know you need to have 4 on the ground. I have 300 + nails. I know they're not all straight. Be patient.



Singledad2019
Apprentice
Apprentice
Posts: 15
Joined: Mon Nov 18, 2019 3:41 pm
Location: Milwaukee, Wi

Re: New builder needing help

Post by Singledad2019 » Sun Dec 15, 2019 6:26 pm

None of the ones I have are either. I got it sitting how it was. It did take be patient. It basically done. However, my new issue is that his friends car is way faster than his. The friend come over to test on the track with parents and there car was much faster. I guess it's time to build a new car.



Speedster
Pine Head Legend
Pine Head Legend
Posts: 1912
Joined: Sat Feb 18, 2012 2:48 pm
Location: Toledo, Ohio

Re: New builder needing help

Post by Speedster » Mon Dec 16, 2019 5:46 am

You don't need a new car. Your car is fine. You did a good job on it. So far you have followed science, What has happened is you have stopped following science. The block of wood is done but you have a LOT of work to still do to make that block of wood go down a hill fast following science. I know you want the car to go fast. How badly do you want the car to go fast? First, you need the knowledge. Second, you need to follow that knowledge. Have you ever wondered why the same racer wins every year? There's no such thing as luck and he doesn't have any secrets. It's PHYSICS, the Science of matter and its motion.

Here's what I'd like you to do. Set your car on the track near the bottom of the hill so the car will roll very slowly. Watch the car and tell me how many wheels are dragging the rail.

QUESTION: Troy Thorne's magazine, "Build a Winning Pinewood Derby Car". Have you read the magazine at least 3 times? Have you studied, studied, studied pages 80 thru 87? You are very fortunate. You now have your friend with a faster car then what you have. If his car happens to be very, very fast then you have a situation that is almost as good as a timer.
We will not be able to bend nails to the degree that is recommended but I guarantee you ANY bend will affect the direction of the wheels.

Please go on Youtube and watch the video "Easy Pinewood Derby Car WINS using science" .

I ask you again, How badly do you want that block of wood to go FAST?
Did your friend sand his wheels?
When is your race?
We need the rules.

Here's a short story. Randy Lisano ran the race for Ford Motor Company in Detroit. There were 100 Girl Scouts racing. The winner of the race was a simple wedge that looked just like your car.



Singledad2019
Apprentice
Apprentice
Posts: 15
Joined: Mon Nov 18, 2019 3:41 pm
Location: Milwaukee, Wi

Re: New builder needing help

Post by Singledad2019 » Sat Jan 11, 2020 9:22 pm

So I ran the car at the scout event. It's best run was mid 2.7s. Which got me 9 in my class. There where 14 cars in my class.



Kenny
Master Pine Head
Master Pine Head
Posts: 292
Joined: Fri Aug 22, 2008 4:19 pm
Location: Houston (Tomball), TX

Re: New builder needing help

Post by Kenny » Fri Jan 31, 2020 11:57 am

This thread has been an interesting read after such a long time away from PWD. I sense disappointment and frustration by OP.
Hang in there. You’ll do better. You’ll both figure out what, if anything, you missed or miscalculated.

Don’t get frustrated, just figure it out. How did the winning cars behave on the track vs your car? Is your car smooth and quiet on a test run, or is it noisy and fishtailing down the flat? Was your car in the lead into the transition, but lost ground on the flat? Try to analyze and assess the difference(s) between the champ and your car on race day.

Despite your best efforts, a little luck does play a role sometimes.
You and your Scout do your best. You absorb all the local rules, and you build and prepare a car according to all the best practices of the day. You've distilled all the tips, and you build and tune for the type and length of the track which you think you will race your cars upon.

Your Sons’ aerodynamic masterpiece with perfect 5.0 ounces and perfectly canted axles, mirror polished and precisely set to kiss the rail (or not) just so on the track. Lubed and staged, it's now out of your Sons' and your hands. Science and hard work have been applied, yet many variables remain. Variables that you cannot control.

You cannot control how your car is handled once it's been weighed and staged by heavy-handed handlers and race officials (This happened to my Son). You cannot control that your car is accidentally dropped, or that is literally so fast it flies off the end of the track bypassing the stops. (This happened to us too, and it mangled our alignment then broke the car!) You cannot control which of the three tracks you'll draw at District, nor can you control how well the tracks are set up or prepared for race day. You cannot control that you're facing a 28 ft wooden track at District after you've built and tuned for success on a 45 ft aluminum Pack track. You cannot control how unfamiliar judges may interpret ambiguous rules on race day. I can go on and on. Yes, science will have you build the best 5 oz wood car you can within the rules and your anticipated race environment. But, all you can do is your best. Apply your experience to the next year and take care of the things you can control.

If speed is the objective, then I would say two of the more important things are: 1) attention to details and cleanliness while taking EVERY advantage permitted by your rules, 2) meticulous tuning, and prep for the length and type of track you will compete on. People, locally, know the answers to all your questions. Find out who they are and ask away. Be prepared. Then build and test, test, test.

Keep at it. Have fun with your kid! It's over in a wink. Do your best. Be proud of their effort. And, a lucky hat or rabbit's foot might not hurt on race day ;)



Post Reply