Pinewood Prius?

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.

 

I can't help, but please do post pictures after you build it.

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Jan 2 2007, 11:25 PM) [snapback]369871[/snapback]</div>

That would be better than getting the angles.

 

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

 

post-troll:

 

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.