Derby Talk

I've uploaded all the car photos we took at last Saturday's Pack 242 Pinewood Derby and placed them on a webpage at:
http://www.richardcmoeur.com/242pwd2016.html

We take four photos of each car: front left, front right, rear left, rear right. This way the boy and family has a record of the car (and we can take a look later if a car in a future year looks a bit "too familiar". )

Our family's cars:

• 3rd overall - Duncan (our son), "DuncMobile". Standard wedge with a marble "energy source" encased by 1/4" Pb wire "roll cage"/weight. Driver (apparently texting) came from a set of plastic "public safety workers".
• 4th place, Adult - my "Bus-ted" bus (tall block) - faster than expected, considering the size. Lighting system came from a deceased LED plastic sword.
• 8th place, Adult - I wasn't planning on making a second car, but my lovely wife wanted an oval car (see 9th place below) and this was the prototype. I looked at it and realized that it resembled a signal once you slapped on the proper color circles, and "Red Light, Green Light" was born.
• 9th place, Adult - my wife's "Emoji Mojo" car. Given that the little people in her phone are much more important than those annoying meatbags in real life, this was a natural. But even though I gave her the best set of wheels and axles I made this year (in terms of spin-testing), I'm still in the family doghouse because it finished behind my cars.

We also have event photos on the Pack's Facebook page at: http://www.facebook.com/media/set/?set= ... 2093002250 .

One more thing: several of the cars combined rear weighting with forward-placed wheels, and the resulting CG barely ahead of the rear axle made for some... memorable racing.

One more-extreme example, caught on video: http://www.richardcmoeur.com/scout/2016 ... blycar.mov( QuickTime .mov format)

That wreck was spectacular !!! It looked like it was out of control from the very start. Do you know what caused it to do that?

Looking at the video (and from my recollection), the car was fine until it reached the level segment at the end of the vertical curve (track is a 32' {27.7' start to finish} Piantedosi.) That's when something imposes a bit of up force on the car nose, and the dance begins.

As I mentioned above, there were several cars like this this year - rear weighted but with wheels forward (long part of the block to back). The result is a CG barely in front of the rear wheels, and any change in down force in front causes the front to rise and wiggle.

Correction: a frame-by-frame analysis shows yaw beginning around halfway into the vertical curve.