My kids are tiger cubs in the cub scouts and we've got the pinewood derby coming up at the end of the month. There's an "old codgers" division that I'd like to enter with a mock-up of a Prius for my racer. i'll need to add some height to the stock car block that you get to accomodate the shape, but was hoping I wouldn't have to reinvent the wheel if someone else has already done a project like this. It would also help to have some basic dimensions...slope of hood,slope of windshield, height and length (so I can build to scale), etc. Anything will help. Look forward to any input or suggestions.
I can get you some angles tomorrow with my angle finder. I remember when I made mine. It was just an arrow dynamic wedge. Got 3rd place. I would love to make one now knowing more about arrow dynamics and how to reduce friction on them.
Mine was blue/gold.... ahhh... memories. I can't wait to see the pictures if you end up making it, Evan.
I suspect the wedge may be one of the best designs for speed...I just thought it would be cool to do a Prius. if you can get me some angles that would be great...not a lot of detail, just the main stuff....hood, front windshield and rear windshield.
I'd get a good side shot of the Prius, blow it up to size, print it out, and trace it onto the side of the wood. That would give you the general shape of the Prius. From there, there's not much left since the sides of the car are about as aerodynamic as a block of wood anyway! Please - and I can't stress this enough - leave the Razorback emblem off the small one.
<div class='quotetop'>QUOTE(TonyPSchaefer @ Jan 2 2007, 11:25 PM) [snapback]369871[/snapback]</div> That would be better than getting the angles.
Tony....I could just build a Razorback Racer!! That snout's gotta be pretty aerodynamic right! I may print out a picture....I'll have to be careful with the size, but that's fairly easy.... I sure hate admitting when you have a good idea....:-(
Hmm. Definately alternative fuel vehicle without being an EV. Make sure you paint HOV stickers on it.
I've got three different die-cast models of the thing. Seems that would be a good way to get all the angles right too!
The 1/30 scale model looks like it would be close, but I haven't seen a cub car since I made a McLaren MD8, and that was just a few decades ago. I'm not sure how important aerodynamics are on such a short course. Would a heavier car be faster? Are any modifications to the nail 'axles' allowed? Some very fine sandpaper and a coat of nail polish would do wonders for the rolling resistance.
Evan didnt you get one of those 30th scale models? another thing that you might try, take some pics of your car get some good side profiles, print it out the size you want, then tape to block and start cutting. when i did my pinewood racer that is how i did it.
<div class='quotetop'>QUOTE(efusco @ Jan 2 2007, 08:29 PM) [snapback]369874[/snapback]</div> Right after the Capital One Bowl game? I'd wait a few months, if I were you.
<div class='quotetop'>QUOTE(hyo silver @ Jan 2 2007, 08:51 PM) [snapback]369893[/snapback]</div> If there were no resistance, the weight of the car would make no difference. Assuming this is a gravity car, resistance is the only factor. That should be wind resistance (negligible at low speeds unless there's a strong wind) plus the rolling resistance of the tires plus the resistance of the bearings or axels. Assuming less than optimal tires and bearings, a heavier car might cause more drag in the tires and bearings. I don't know what restrictions there are, but using really good racing-bicycle wheels with the high-pressure narrow tires ought to be the most useful thing you could do. But if the course is long enough and steep enough to build up fast speeds, then handling could become critical.
<div class='quotetop'>QUOTE(daniel @ Jan 3 2007, 12:26 AM) [snapback]369921[/snapback]</div> Agreed. When I did the pinewood derby my father gave me some clarinet components to use instead of the nails, and we used trumpet valve oil to help reduce friction. I don't know what the current rules are, but it met the weight, & height requirements. The tires sound like a good idea as well. The nails that came with the kit were not as finely ground around their edges as the clarinet components (stems) and caused additional friction. If you have to use the provided nails, I would suggest buffering them down to as smooth a surface as is possible. David
<div class='quotetop'>QUOTE(IsrAmeriPrius @ Jan 2 2007, 10:56 PM) [snapback]369898[/snapback]</div> Hate is such an ugly thing! Yea yea, it was a really good game, I think the Razorbacks led almost every stat except for yards passing and the important one...the final score.... Them making a 52 yard FG and us missing a 30 yard one also made a big difference...
My boy and I built one last year. I think we used the picture method to get the basic shape and then we got some letters and printed Prius on it. The kid is not one for a huge amount of detail. If you want to win the race the most important details are weight, round wheels and sanded and polished axels. Our first couple Pinewoods didn't do to well because we spent more time on the look of the car and not enough time on the weight, axels and wheels. Have fun, Matt Denver
Years ago I entered a 'mystery' car into the local Pack's Pinewood Derby (since I couldn't be a Cub Scout, after all)...with six wheels instead of four, that were staggered (if you compared the LH and RH sides of the car). You'd think the extra friction would have been a hindrance, but it did seem to run faster than expected, for some reason. The hypothesis at the time was that the six wheels tended to make the car run truer, and not wander back and forth in its track(??) I purposely made the block of wood itself look really, really rough, but tried to be sure that the car rolled *as straight as possible* when I placed it on the ground and gave it a little push.
A few hints from a old Cub Scout Leader. Build a chuck and place all 4 wheels on and using sand paper round and size the wheels. Graphite is a good lubricant. Drill holes on the bottom and glue in lead shot to get the racer within a gram or so of the limit. Those are my tricks.
