Speed Fluctuation

[Black Fox]

Gents

As many of you already know, my son took 1st place at our pack PWD. Despite his win, I noticed some big speed fluctuation, I was able to get the track data.

Here are the times of his car.

2014 Speed Records

3.177
3.214
3.105
3.101
3.107
3.286
3.21
3.218
3.177

As you can see, there are some big difference in speed.

When I compare this to the car that took first 2 years ago, his speeds where more consistent.

2012 Speed Records

3.189
3.181
3.147
3.135
3.176
3.128
3.189
3.18
3.183
3.195
3.194

Now I mentioned in the "Steering Question" thread that his FDW was loose and we stuck dental floss in to tighten it up. So I'm thinking maybe his wheel was bumped and allowed the pitch to change thus creating big speed fluctuations.

However, Kinser and Papa V racing mentioned that graphite on the rear wheels could cause problems. I had my son wipe the wheels but not the inside of the wheels. After the race and reading their comments I noticed there was a fair amount of graphite left over on the inside of the wheel from when we burnished it. So I'm wondering if graphite got on to the wheels and caused sporadic slippage which caused the time to fluctuate.

Perhaps you all might have some other ideas as to why the speed fluctuated so much.

 

[Obsessedderbydad]

Couple questions. Are those times in order of his runs? Also, who staged the car? Scout? Leader? You? If the car is staged the same every time you wont see these different times, because hypothetically the car should run down the track the same each time. Granted, lanes run differently and also different cars your running against will effect your car as well. If the car is staged differently each time, your times will be inconsistant. As I saw in my sons car at districts. The first 8 were Den and Finals race. The last 4 were the Grand Finals. You can tell where the starter took more time in staging the car. This was also 12 runs, not 8 like most do. So we were more consistant and faster at the end. 4 Lane 35' Best Track, so dont freak about the times.

2.210 216.0 1

2.204 216.5 1

2.230 214.0 1

2.223 214.7 1

2.208 216.2 1

2.213 215.7 1

2.214 215.6 1

2.207 216.3 1

2.207 216.3 1

2.207 216.3 1

2.207 216.3 1

2.208 216.2 1

 

[IAE Racing]

Hand start or solenoid start? Staging. Track setup. the cars beside you Like ODD mentioned. All would have an effect. Some cars are also more consistent than others.

 

[Obsessedderbydad]

Not to mention, if you added graphite right before you checked in your car. If you didnt spin the wheels enough, that extra graphite you added can slow you down for the first few runs.

 

[DEW36]

I would also check your DFW for a steer change. I had my son's car set to 3" over 4' and when we took some damage and his car slowed down some, I rechecked his steer and it was now 8" over 4'. One other thing I noticed with our race was the track looks like it has never been cleaned and two of the lanes had a ton of graphite on them and it was hit or miss if my daughter's car would get the wiggles from it.

 

[quadad]

Those time differences are HUGE ! If you really want to understand where the issues are you would have to be able to correlate track lanes with each of those times. I would guess however that because there are some similar values repeating at different times and no real pattern (i.e. getting faster then getting slower) that much of the issue is with the track (lanes, release mechanism, etc.). Graphite cars always seem to vary more, but not that much. I don't think a little graphite on the inside of the wheel is any issue.

His FDW axle was loose so you put dental floss in the axle hole ? That must be pretty loose. Did you check drift after the race ? Is there any way to get on another track (any decent track) to see how it is doing before district or council race ? Careful about tuning on a different track style (wood vs aluminum and shorter vs longer) though. We always drilled tiny holes to glue the axles in because of our Pack's stop section, etc.

 

[Black Fox]

Thanks guys. This really helps. I'll see if I can get tha data on the other cars to see if they were inconsistent too.

It seems that it may have been a combo of how the cars were placed on the track and the graphite. I was the one who placed the cars on the track. I wasn't planning on being the staging guy but I was asked just before the race if I would do it. We have had problems with our solenoid s in the past with the gate releasing after a minute or so. Our tech guy said he fixed this but just in case there still was an issue, I was trying to load the cars quickly and as a result I probably didn't line the cars evenly. Also, I never realized that placing could create such a big difference. I will let the guys know about this for next year. I'll also have them test the gates to see how long they'll hold before releasing. So the person staging the cars will know how much time he has to set them.

As for the graphite. I do not know if the track was cleaned before the race or not. But After the race I helped take the track apart and my hand was covered in graphite when I was done. I've taken the track apart before and I can't recall my hand being that dirty. So I'll pass the word to make sure that the track is cleaned before the race and also put the word out to the scouts to wipe their wheels clean before bringing their cars.

About the time I presented. The spread sheet indicates that the times are in order with the bottom time being the first race and the top number being the last race.

 

[quadad]

Your gate solenoid must be energized in order to hold the cars (i.e. keep the gate "closed") ?

If so, that is pretty unusual. Usually the solenoid is only energized to release the gate open. That allows us to use solenoids at their momentary rating as opposed to a continuous duty rating. It sounds like maybe your solenoid can not handle the one minute continuous operation. If so, I would change the operation or the solenoid.

 

[Black Fox]

Those time differences are HUGE ! If you really want to understand where the issues are you would have to be able to correlate track lanes with each of those times. I would guess however that because there are some similar values repeating at different times and no real pattern (i.e. getting faster then getting slower) that much of the issue is with the track (lanes, release mechanism, etc.). Graphite cars always seem to vary more, but not that much. I don't think a little graphite on the inside of the wheel is any issue.

His FDW axle was loose so you put dental floss in the axle hole ? That must be pretty loose. Did you check drift after the race ? Is there any way to get on another track (any decent track) to see how it is doing before district or council race ? Careful about tuning on a different track style (wood vs aluminum and shorter vs longer) though. We always drilled tiny holes to glue the axles in because of our Pack's stop section, etc.

My son accidentally put graphite on the axle then stuck it in the hole. So I think that was why it became loose. He also could have put it in properly which may caused it as well. Before that it was snug.

I did check the drift and it was turning in a bit harder. I didn't know about the 4" & 4' rule until after the race and the board i was testing it on is only 3-1/2'. Butt after doing some calculations it seems I had the car set a 5.5" @ 4'. When I check it just now it was about 4.5" @ 4.

 

[Black Fox]

Not to mention, if you added graphite right before you checked in your car. If you didnt spin the wheels enough, that extra graphite you added can slow you down for the first few runs.

Yes you mentioned that before in the Burnishing thread. Just before the race we did add graphite but spun it 3 or 4 times before checking it in.

 

[Obsessedderbydad]

Even after adding graphite and spinning the wheels normally the first few runs are slower. Your drift isn't terrible though. 5.5" over 4' isn't bad. Something was defineately off for the times to be that different

 

[Guest]

What kind of track was it? I know our pack track is a 6 lane 48’ home made aluminum track that has a few lanes that much slower than the others.

 

[Black Fox]

I'm not really sure and I don't have a picture of the track. It's a 6 lane 42' aluminum track. The track is completely flat and you lift one end which gives it a gentle curve. There are 2 folding supports attached to the track which hold the track up.

 

[IAE Racing]

Your gate solenoid must be energized in order to hold the cars (i.e. keep the gate "closed") ?

If so, that is pretty unusual. Usually the solenoid is only energized to release the gate open. That allows us to use solenoids at their momentary rating as opposed to a continuous duty rating. It sounds like maybe your solenoid can not handle the one minute continuous operation. If so, I would change the operation or the solenoid.

I would want a person controlling the release. If racers/stagers have to ever hurry -not good.

I'm not really sure and I don't have a picture of the track. It's a 6 lane 42' aluminum track. The track is completely flat and you lift one end which gives it a gentle curve. There are 2 folding supports attached to the track which hold the track up.

If the track is that flexible, there could be A LOT of variance between lanes. JMO

 

[Quicktimederby]

The time variance is HUGE!! I would think the gate and the track would be the most likely cause. And if you car happened to wiggle bad enough you will see big slowing like that. On a scout car the stage really wont slow you down much unless the car is on the edge of being stable. People make a big deal about staging, which from my testing doesn't effect the time that much not enough time for a scout race. A league race is where cars are separated by .00xx then it could be a issue. For fun I ran my bearing car 4 times, 1st staged like I like it, next with the rear non dominate wheel on the rail, 3rd with the dominate rear wheel on the rail, and last just set it up there. There was only a .004 difference between the fastest and the slowest. And go figure the fastest was when I just set the car up there!!! I should have payed attention on how I set it up there!

 

[Black Fox]

Half of the races my son's car had no wiggles. When he didn't he was running under 3.2 sec. When he did, he was running over 3.2 sec. The wiggles were light to moderate but in one run it wiggled a lot. That's when he got the 3.286 time.

 

[Kinser Racing]

Wiggles (IMO Drift, lol) will slow you down but IDK if it will slow you that much. It could be a combination of the start gate, drift (wiggles), and dirty wheels.

 

[Black Fox]

I'm almost starting to wonder if I put the car in the wrong lane on that race. It's just so way off from the others.