Track Speed Change in Mid-Derby?

[Curse You Red Baron!]

At our PWD event my son ran an average of 2.337 in his webelo Den to claim first place. The top two cars of each Den competed in the Pack Championship race, which took place about 90 minutes after the Webelo Den race. His time improved to 2.236 seconds: a full .1 second improvement. The same was true of the second place car in our Den. I didn't have the Den race data on the other cars.

The only explanation I can think of is we have a manual gate, not spring loaded, but the gap seems too consistent. Any Ideas why this would be?

[drathbun]

Lots of graphite falling on the track, making the surface slicker.

[pgosselin]

It could be the manual gate. It could be a problem with the timing software. It could be the graphite. Maybe it wasn't fully distributed on his runs during the Den races, but was fully broken in by the championships. Or it could be the style of car. If it's a straight runner, he might have had a few near perfect runs towards the end where the wheels almost never touched the rail.

There are some here who are far more qualified than me to figure it out.

Paul

[sporty]

Just sounds like something was bumped to me. just enough to change it a little. Does not take much.

Thats not a bad jump, and it was consistent for you and the other and perhaps more.

I am sure going back to the data, you could see when it happened.

For a manual release, no spring, wow thats not actually a big differance. I use to see bigger swings in time than that.

[Curse You Red Baron!]

We ran a rail-rider, and seemed pretty consistent on our times, relative to the lanes. Car had good physics, but not quite optimized, due to time and Cub skills, as he did the work or participated significantly ( ). Also, the 2nd place car had the exact same change in time (and going purely off of memory, the Pack Winner had picked up a similar amount of speed also) so I really don't think it's either car.

Drathbun, you may be right about the graphite, tongue in cheek as your comment may have been (!), I had always thought that slicked or irregular wheel tread tended to slow a car (I slick the edges and hubs, but try to keep the tread clean) due to reduced traction. Maybe it depends on the track? Maybe graphite on the track slows you on an aluminum track but helps on a wooden track with it's share of dings and irregularities... interesting. Thanks for the input!

[drathbun]

I keep the track for our pack now, and our former cubmaster has forbidden me from cleaning it. He thinks the years of accumulated graphite makes our track faster. I have no idea if he's right. We do have a wooden track, but we've kept it in relatively good shape. Our overall pack times have continued to get better every year.

[sporty]

On wooden tracks, the graphite tends to stick on the wheels and make the track more bumpy also. The same for a aluminuim track.

Graphite on a aliminuim track would make it more slicker and could cause wiggles or RR issues. No so much as on wood.

A track should be cleaned or wiped down after a days racing is done.

Also if they were using rubber bands for the manual release gate, one of the rubber bands could have broken or began to stretch out more, after being used all day. I would highly doubt it woudl re related to graphite on the track, that woudl slow you down, not speed you up.

Sporty

[Curse You Red Baron!]

Sporty, just saw your comment, that does probably make the most sense. thanks! I have to say, in an arena where my cub is struggling for another .03 seconds or so of speed (I know it's there, and more, I just need to help him get there!), that's a pretty big swing just built into our Pack race process, makes you think. A few folks with cheater bars got full advantage of the slow manual release, including the 2nd place in Pack, but council uses a spring-loaded gate so it won't be a variable there.

[sporty]

no problem.

I have had two wooden tracks , 3 years worth of running on it. sold my last track last year.

I have ran on a variety of tracks over the years. Back in 2006/2007. i was going over to my friends place every week starting on october and finally in 2008. he said here you can have it. lol.

They were done with scouts, in 2010 I got one from woodworx on here, be built it and thats the one I sold last year.

I still haev access to the two tracks I use to own. but no need to go and use them. lol.

Sporty

[RRS73]

I don't buy the graphite theory. The finish line timing sensor probably got bumped. All it takes is a little bump and your times improve (or get worse) drastically. Our race times this year on a track that is nearly 50 feet long were an average of 0.2 seconds higher than last year.

We borrow the track from another pack, and they run our races for us. I know the other pack's leaders well, and they asked that I bring our car from last year on test and tune night (cub was 2nd place for the pack last year). They wanted to calibrate their timer, and had my cub's times from last year. Old car was well kept in a baggie, checked the weight, lubed it up good with graphite, and wham! It was 0.2 secs slower than it was last year. This year's car smoked it, but it registered a slower time than last year's car in last year's race.

When the other pack was running their races later that day, they found that the timer wasn't set properly, and bumped it back to where it was supposed to be before they ran their heats. The other pack was getting times near our pack winners with seemingly slower cars.

All it takes is a small bump on the finish line timer. Someone probably bumped into it.

[drathbun]

Our timer goes through holes in the track and screws in place. I'm not sure I can see how it can be bumped one way or the other, at least in our case.

[RRS73]

Our timer goes through holes in the track and screws in place. I'm not sure I can see how it can be bumped one way or the other, at least in our case.

I think the one we were using was set with magnets (?). Could it be that the screws weren't in all the way and it got bumped. If it is a laser, could the angle not be perpendicular to the track surface if screws weren't in all the way and it got moved?

[Curse You Red Baron!]

RRS73 our timer is a screw-in also, though I imagine it would work when the top is anywhere within about a half inch of vertical... I'm not sure of the play. I can definitely see a loose timer, the Boy Scouts of the Pack often help, and their construction tends to be a bit... haphazard.

As for the graphite theory, one of the folks with a real track at home will just have to test it! I'm skeptical, but in the real world there are sometimes variables whose importance we misjudge (Bumble-Bees should not be able to fly, anyone?), so until someone tests it I'll keep an open mind.

One other year to year variable if you happen to change sites is the slope of the room you are in. We've been in three places the last three years. Last year the track itself was on on a downward slope and I didn't realize it; I was wondering how the cars could be so much faster than the year before! Knocked about .15 seconds off the best times.

[idpwdnut]

I have had temperature changes affect the times. One year while my son did some testing for a science fair project, shop had overhead heaters. Had ran probably 30 heats prior to heaters being turned on, then times increased. Turned heaters off, track cooled back down and times returned to normal. I did not think the effect would take place so quickly but it did.

Barring temperature differences, maybe ramp portion of track got bumped lowered starting gate height.

[FatSebastian]

I have had temperature changes affect the times.

Us too (although I don't think it amounted to the ~1/10 of a second that CYRB is looking for).