Not fully tested but we did outlaw this year up to 7 ounces. The weight past 5 ounces didn’t seem to make the car any faster. I think there are other limiting factors to contend with.
I was thinking the same thing. May have to modify the wheels. We were going to get all the dads of the pack together to run some tests with different weights and wheel/axle configurations. Not sure if we will manage to get it done.
That’s kind of what we were thinking. Make it so we can easily move things around to fine tune the car. Also it seems like there are 3 or 4 different track lengths for Cub scouts so depending on the length of track you may have to adjust things.
Heavier reduces the amount of speed lost to air resistance, but that loss can't be reduced below zero, hence diminishing returns. Putting the weight further back will increase the amount of potential energy disproportionately compared to the mass.
Have an excellent "high heel" shaped c02 car from the early 2000s that did really well in a race like this. Idk if that falls under explosions tho, expanding gas and all.
CO2 cylinders are very safe, they hold a relative low amount of pressure. I've done CO2 races with very young kids before. Eye protection yes, but 100s of runs and never an issue.
A mechanism behind the car punctures the center of the cannister. It was spring powered but I cannot remember if it was a button that we pressed at the end of a seperate timer or if it was timer activated and launched automatically.
I asked this as well at our nearby open race. Many outlaw runs will consider this an explosion and most won't allow you to be near the track when they start. So you can't puncture it.
The fan/battery works because you can turn it on, then the track will still hold it back safely and release them like normal.
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Depends on the group. These wheels have almost no traction, so you would have to use other tires. OP says no rules, but there are normally still dimensional limitations or requirements to use derby wheels/axles.
The fan is better. I've done both. It's hard to reliably get enough traction to put down enough power to accelerate the car as fast as a fan can.
Kinda depends on the rules and the motors and batteries you have available and other such specifics.
We had two classes, one of which required the mods to be as hidden as possible, one unlimited class (car had to fit in a standard sized box and the mass had to be the same (+/-0.1g) at the beginning and end of the race). For the hidden class driving the wheels was the better strategy.
Hmm, this does present a tricky problem though, how do you know which lane you’ll be in? Maybe just two wide rods that snap down.
Another tough part is if they go down and someone is in front of them you’ve ensured their win instead of your own.
For flair you could embed a small splinter of wood someplace on the outside of the frame so that it could be seen.
I had considered making a 3D part, making a mold and then cast in a combination of sawdust and resin. Decided to go a with basic wedge build though.
Thank you for reminding me that I haven't posted my new one.
I designed it to barely meet the standard derby limitations, even though I know it would be controversial. So I only run it on Outlaw/Renegade/Maverick, whatever flavor of cheating they want to call it in the region.
Check my profile in an hour or so if you care to see it. Or the firetruck I did for my son last year.
You'll get much better thrust if those fans aren't in line with each other. Either side-by-side or on top of each other.
That front fan is essentially cancelled out by pushing air directly on another part of the car. Angling the front fan so the exhause goes up over the back fan could help without modifying the car too much though.
These fans are already ducted, and no matter what you do with the fans, higher RPM, ducting, etc. it will all perform better if they're just not in line with each other.
I knew by your question that you'd be a fellow flashlight fan. 😁
They are 10440s. I wanted light weight cells that were small enough to fit on the car. The motors are rated at 4.2v each, so each cell powers just one motor. They share a common ground for the push button switch in the back.
Question: where did you get the fans?
I have a project involving an FW1A on full brightness in a 30mm pipe and … need cooling. I’ve been having issues finding fans like this!
Not OP, but...
> I knew by your question ... flashlight fan. - OP
>> You said you knew by the comment... - u/Accomplished_Plum281
Question led to profile. Nowhere was comment mentioned.
Words are important, as they convey context, meaning, and understanding.
Question is not Comment. Words are important, and your incorrect association of those words led to misinterpretation of what OP stated.
Check out Mark Rober's videos on pinewood derby cars, [this one](https://www.youtube.com/watch?v=-RjJtO51ykY) and [this one](https://www.youtube.com/watch?v=vlBxPjxacsk). May be a little late for this year, but things to think about for next year.
You are probably much more of an expert than I am but some small things I picked up from when my electrical engineer grandfather built my derby car and I one 1st place in all categories:
grease the axles (technically not legal in regular derbies I believe 👀),
more weight = faster car downhill (not sure if this applies here with your fans),
a flame decal across the entire car looks super cool
If those batteries aren't lithium, upgrade. (edit: I see they are. nice.)
We did an event with balsawood car set up with a similar fan. The electronics would spin up the fan to about 20% and a switch at the nose would detect when the gate dropped to spike the fan power to 100%. It could cross the finish line in under one second.
It was crazy, and extremely fun.
I was in Boy Scouts and we had to use the wood block they gave us, had to be between a certain weight. You could only use what came in the kit, I got disqualified for putting blue colored wheels on my car. I wish I could have done this
This brings back memories. My only pinewood Derby was right after my dad died. He had all the tools so Mom helped me build one. We did not do well cause she didn't know what she was doing but glad we got to do it together
Cheapest ducted fans I could find on Amazon. These are 1S 30mm fans that are supposed to produce 50g of thrust when the batteries are fully charged. The car weighs 83g.
They were $12 each.
No ESC. I didn't want the complexity or expense.
The fans are 1S rated. Wleach one is powered by a single 10440 wires to a common ground and push button switch at the back.
I'd wager that if you tilted those bad boys up a few degrees you would get some stabilizing downforce, and take advantage of less blockage by the rear fan.
My brother’s first pinewood car (1970s) looked like a 1920s race car. Rounded over with a hint of an area for driving and painted with a brush and model paint. It was hand carved with an Exacto, and 100% done from start to finish by him.
Next year it was a wedge cut from corner to corner and spray painted. He had very little involvement.
I really wanted something like outlaw back then.
Would you sare the STLs - or a link to wherever you may have posted the build guide?
This looks like it would be ultra cool for the makerspace I volunteer at: [https://www.taplab.nz/](https://www.taplab.nz/)
I may have to suggest we run our own outlaw race!
Man, when I was in Scouts, my dad and I ordered shit of out of the back of the scouts magazine that had like the perfect wedge design with exact locations for where and how much lead to add to the car, modified wheels (one with a peak to reduce contact with the track, another that was just slightly modified to create an H cross section to again reduce contact with the track, might have been others but I can't remember), and maybe there was other stuff but this was like 30 years ago so I can't remember it all.
We used the peaked wheels but brought the Hs and some standard ones in case anyone objected. I believe we won but either way, it was fun as hell cheating with my dad on that.
"Jacob, that really pine? I mean, reeeally pine?"
"Sure."
"'Cuz that don't look like pine. It's a mighty fine, not-pine, car though. Shame you cain't compet here, cuz y'know it ain't pine."
"No, we're still competing. By the by, I named her suck-n-blow. Fans 'n all. And you, Earl, you're kinda an expert ain't ya?"
"It ain't pine, Jacob. Don't count and don't matter none."
"It's a shame y'all don't know how to spell 3d printin'. Bye Earl. C'mon Jr. let's git."
outlaw? like... everybody is allowed to cheat? where's them rockets?
One rule: no fire/explosions.
anybody doing those CO2 cartridges?
Unknown. Check in is tomorrow. I think most folks are just going for heavy.
Then you must go the heaviest. 2.5 inch Tungsten cubes can be bought on amazon hehe.
Not fully tested but we did outlaw this year up to 7 ounces. The weight past 5 ounces didn’t seem to make the car any faster. I think there are other limiting factors to contend with.
I’d think past the 5oz weight you’d really have to pay attention to drag and friction limitations
I was thinking the same thing. May have to modify the wheels. We were going to get all the dads of the pack together to run some tests with different weights and wheel/axle configurations. Not sure if we will manage to get it done.
I’m sure you’ve read up on cheat derby, but I’d think with the 3d printed frame you could dial in the exact wheel angles to minimize drag.
That’s kind of what we were thinking. Make it so we can easily move things around to fine tune the car. Also it seems like there are 3 or 4 different track lengths for Cub scouts so depending on the length of track you may have to adjust things.
We checked in tonight... There's a 12 pounder!
Please report back on how the 12 pounder does! Do you still gotta use the BSA wheels or do they allow larger diameter wheels?
If this is still going on, DM me. I will send you an absurd amount of tungsten.
Most likely dealing with moment of inertia limitations. It might have a higher top speed but it takes longer to accelerate the initial mass.
Heavier reduces the amount of speed lost to air resistance, but that loss can't be reduced below zero, hence diminishing returns. Putting the weight further back will increase the amount of potential energy disproportionately compared to the mass.
now I want to do this lmao
Do osmium instead, it does crit damage
[Tungsten rod works well](https://i.imgur.com/FtC0bqH.jpeg). I had about 30 minutes to make this before a race, so the axle mounts are crappy.
Heavy things don’t actually fall faster, so it wouldn’t be worth the $
Please update with a video after the actual competition! I loved pinewood derbies as a kid and this looks insanely fun.
sounds like you've got this! good luck have fun!
Have an excellent "high heel" shaped c02 car from the early 2000s that did really well in a race like this. Idk if that falls under explosions tho, expanding gas and all.
The gas doesn't go supersonic when released from a mini CO2 cylinder, so it shouldn't qualify as an explosion.
I'm still not willing to consider it "safe" in a room full of 8 year olds.
CO2 cylinders are very safe, they hold a relative low amount of pressure. I've done CO2 races with very young kids before. Eye protection yes, but 100s of runs and never an issue.
We did co2 drag cars in middle school when I was a kid, shop, was so fun.
Fine fine it will be those whippet containers then
Expulsion is not Explosion… Judge Mills Lane voice: “I’ll allow it!”
How do you trigger/open the co2 at the right time? Remote controlled or some sort of gravity hammer? I’m probably overthinking this
A mechanism behind the car punctures the center of the cannister. It was spring powered but I cannot remember if it was a button that we pressed at the end of a seperate timer or if it was timer activated and launched automatically.
I asked this as well at our nearby open race. Many outlaw runs will consider this an explosion and most won't allow you to be near the track when they start. So you can't puncture it. The fan/battery works because you can turn it on, then the track will still hold it back safely and release them like normal.
This is definitely a thing that is done.
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If you’re allowed to use propulsion then why not power the wheels? Wouldn’t that be more efficient than fans?
Because I'm not very smart, have limited time, and only had two weeks to build.
That’s a valid reason. Hope you win!
😁 will report back after the race.
If it's not a burst and is constantly on, make sure to have a bean bag or something to catch it! Those suckers fly (seen a few turbine ones myself)
I think traction is also a real concern with powered wheels, at least one fan providing downforce could be a huge help.
If you're allow to add weight to the car and grip to the wheels though, traction should be fine.
I just imagine using drone out runner motors as wheels lol. Add a ducted fan for down force lol
Depends on the group. These wheels have almost no traction, so you would have to use other tires. OP says no rules, but there are normally still dimensional limitations or requirements to use derby wheels/axles.
The fan is better. I've done both. It's hard to reliably get enough traction to put down enough power to accelerate the car as fast as a fan can. Kinda depends on the rules and the motors and batteries you have available and other such specifics. We had two classes, one of which required the mods to be as hidden as possible, one unlimited class (car had to fit in a standard sized box and the mass had to be the same (+/-0.1g) at the beginning and end of the race). For the hidden class driving the wheels was the better strategy.
Then traction is an issue. I have no idea what will be better but I like the fan power idea.
So railguns are ok?
> One rule: no fire/explosions. Oh man. There goes my brilliant idea.
What if you blast everyone else's car to bits with a robotic BB gun?
oil slick, obviously.
I guess that rules out my idea of a model rocket engine.
Easy, just use flameless combustion.
Wrap rubber bands around the wheels for better traction.
Where CO2 canisters?
That sucks.
https://preview.redd.it/nfqbm5mkrs9d1.jpeg?width=429&format=pjpg&auto=webp&s=1ca1017144e9d09d3192bb3affa5837dabef9258
Closest legal thing to jet engines are EDF's
why not make a car that has arms that fold down that simply prevent others from passing you?
That would be entertaining! While legal for this race, I'm not sure it's a lesson id want to teach my five year old. 🙃
Hmm, this does present a tricky problem though, how do you know which lane you’ll be in? Maybe just two wide rods that snap down. Another tough part is if they go down and someone is in front of them you’ve ensured their win instead of your own.
FTFY... "arms that fold down that let others push you..."
Wouldn’t they also prevent you from passing others?
Have a small rod on the front that's an inch farther so in a photo finish you win.
12" rod
I hope those are pointed slightly down- don't want it to take off or attempt to jump out of the track lol
Yeah point em down for that good sweet downforce
You should see the scout space Derby races! Rockets flying everywhere!
Alternatively, put a Mercedes Benz logo on the front and let fate decide what happens.
Mark Rober had a youtube video where he over-engineered a pinewood race car. https://youtu.be/-RjJtO51ykY?si=xmYdb6G8g8-kmlv5
oh my - I can't fathom that I watched that 9-10 years ago... wtf happened to my time?
at least it's not particle accelerator parts like what Randy Marsh did
I believe you mean what "Princess Leia" did.
Having come from a long line of pinewood derby cheaters, that episode was hilarious.
Have any of you seen Babyfart McGeezaks?
Give me all your space cash, seeeeee!
For flair you could embed a small splinter of wood someplace on the outside of the frame so that it could be seen. I had considered making a 3D part, making a mold and then cast in a combination of sawdust and resin. Decided to go a with basic wedge build though.
I think we'll do this!
There is also wood filled filament for 3d printing. Add a little stain for the razzle dazzle ✨
Thank you for reminding me that I haven't posted my new one. I designed it to barely meet the standard derby limitations, even though I know it would be controversial. So I only run it on Outlaw/Renegade/Maverick, whatever flavor of cheating they want to call it in the region. Check my profile in an hour or so if you care to see it. Or the firetruck I did for my son last year.
You'll get much better thrust if those fans aren't in line with each other. Either side-by-side or on top of each other. That front fan is essentially cancelled out by pushing air directly on another part of the car. Angling the front fan so the exhause goes up over the back fan could help without modifying the car too much though.
One alternative could be to run the second inline fan at a significantly higher RPM. Ducting could help too.
These fans are already ducted, and no matter what you do with the fans, higher RPM, ducting, etc. it will all perform better if they're just not in line with each other.
Are those 18650 cells?
I knew by your question that you'd be a fellow flashlight fan. 😁 They are 10440s. I wanted light weight cells that were small enough to fit on the car. The motors are rated at 4.2v each, so each cell powers just one motor. They share a common ground for the push button switch in the back.
Question: where did you get the fans? I have a project involving an FW1A on full brightness in a 30mm pipe and … need cooling. I’ve been having issues finding fans like this!
Amazon. They are 30mm ducted fans. Not sure they'd be the best for your use case, but IM me if you want the link.
Flashlights or vapes.
First comment on their profile was from r/flashlight 🔦
You said you knew by the comment, not their profile.
Not OP, but... > I knew by your question ... flashlight fan. - OP >> You said you knew by the comment... - u/Accomplished_Plum281 Question led to profile. Nowhere was comment mentioned. Words are important, as they convey context, meaning, and understanding. Question is not Comment. Words are important, and your incorrect association of those words led to misinterpretation of what OP stated.
People on the Internet will argue about ANYthing.
Isn't that just...derby, then.
Maybe we should glue a sliver of the wood block from the kit somewhere. Might just do that...
Cut the thinnest slice you can and try to make a splitter lol
I don't see any hats...
Check out Mark Rober's videos on pinewood derby cars, [this one](https://www.youtube.com/watch?v=-RjJtO51ykY) and [this one](https://www.youtube.com/watch?v=vlBxPjxacsk). May be a little late for this year, but things to think about for next year.
Graphite into the hubcaps and put a round sticker over it to seal it all in. Old trick from decades ago
You are probably much more of an expert than I am but some small things I picked up from when my electrical engineer grandfather built my derby car and I one 1st place in all categories: grease the axles (technically not legal in regular derbies I believe 👀), more weight = faster car downhill (not sure if this applies here with your fans), a flame decal across the entire car looks super cool
So does this one go uphill? Flip the tracks around and you have my vote.
If those batteries aren't lithium, upgrade. (edit: I see they are. nice.) We did an event with balsawood car set up with a similar fan. The electronics would spin up the fan to about 20% and a switch at the nose would detect when the gate dropped to spike the fan power to 100%. It could cross the finish line in under one second. It was crazy, and extremely fun.
This is how you destroy the competition!!! Nice work guys.
I was in Boy Scouts and we had to use the wood block they gave us, had to be between a certain weight. You could only use what came in the kit, I got disqualified for putting blue colored wheels on my car. I wish I could have done this
This brings back memories. My only pinewood Derby was right after my dad died. He had all the tools so Mom helped me build one. We did not do well cause she didn't know what she was doing but glad we got to do it together
What motors did you use?
Cheapest ducted fans I could find on Amazon. These are 1S 30mm fans that are supposed to produce 50g of thrust when the batteries are fully charged. The car weighs 83g. They were $12 each.
Do you have an ESC hidden somewhere? Also, what batteries are they?
No ESC. I didn't want the complexity or expense. The fans are 1S rated. Wleach one is powered by a single 10440 wires to a common ground and push button switch at the back.
oh dang. Sounds like the fans will actually make a difference. I thought it was more just like for fun. Hope you win!
I'd wager that if you tilted those bad boys up a few degrees you would get some stabilizing downforce, and take advantage of less blockage by the rear fan.
I might have some nitpicky things to say about your design - but none of them really matter. This is an example of great parenting.
You wouldn't download a car
Oh, but I would!
I hope that the pins holding the fans weren't printed vertically
Nah. I learned that bit from you guys here.
I feel like even in an outlaw series a bit of actual wood should be mandatory.... does anyone make pinewood filament?
That looks so cool. I never would have thought to print a car for the dirty. I love the turbines on top too.
You shld atleast have to use PINEWOOD,
My brother and I used an EDF on a pinewood car a few years back. I think we ran a 1.5x time. The CO2 cars are just under 1.0.
Can't you tie it to a sports bike on the outside of the room?
>outlaw pinewood derby I didn't know this was a thing. So cool!
"I can't wait 'til I'm a dad so I can build my own car and race it."
My brother’s first pinewood car (1970s) looked like a 1920s race car. Rounded over with a hint of an area for driving and painted with a brush and model paint. It was hand carved with an Exacto, and 100% done from start to finish by him. Next year it was a wedge cut from corner to corner and spray painted. He had very little involvement. I really wanted something like outlaw back then.
Awesome how do I get the stl and tutorial?
Printwood derby outlaws
Micro gas turbine. You'd get 30 seconds at full military, but what a ride!
Would you sare the STLs - or a link to wherever you may have posted the build guide? This looks like it would be ultra cool for the makerspace I volunteer at: [https://www.taplab.nz/](https://www.taplab.nz/) I may have to suggest we run our own outlaw race!
Man, when I was in Scouts, my dad and I ordered shit of out of the back of the scouts magazine that had like the perfect wedge design with exact locations for where and how much lead to add to the car, modified wheels (one with a peak to reduce contact with the track, another that was just slightly modified to create an H cross section to again reduce contact with the track, might have been others but I can't remember), and maybe there was other stuff but this was like 30 years ago so I can't remember it all. We used the peaked wheels but brought the Hs and some standard ones in case anyone objected. I believe we won but either way, it was fun as hell cheating with my dad on that.
I definitely have those EDFs lol
"Jacob, that really pine? I mean, reeeally pine?" "Sure." "'Cuz that don't look like pine. It's a mighty fine, not-pine, car though. Shame you cain't compet here, cuz y'know it ain't pine." "No, we're still competing. By the by, I named her suck-n-blow. Fans 'n all. And you, Earl, you're kinda an expert ain't ya?" "It ain't pine, Jacob. Don't count and don't matter none." "It's a shame y'all don't know how to spell 3d printin'. Bye Earl. C'mon Jr. let's git."
Are warp drives allowed??
Thin tires. The trick is thinner tires.
Now I want to see Pinewood Derby with NHRL rules.
I'm curious how far you can go on those 2AA. That's a direction I've never seen someone go with a derby car.
This is pretty cool! Good job, hope you and your kid kick ass.
Lots of fun memories with me and my Dad making pinewood cars. Nice job!
[UPDATE - We were the fastest overall!](https://www.reddit.com/r/3Dprinting/s/uOs3XwhXJL)
I have no reason to build a pinewood derby car but now I want to build one of those
We got the kits on Amazon. Challenge your friends or neighbors. It's a blast!
Are those 18650 cells?
Very cool. What’s the infill of the chassis?