Empirical Data on RR Value and Track Setup Variations

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Master Pine Head
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Empirical Data on RR Value and Track Setup Variations

Post by PWD_addict » Mon Apr 06, 2009 8:33 am

We ran the District races yesterday on the same track that we run our Pack races on. I was the Chair for both (we won--another post) so I have empirical data on a couple of intersting topics.

First, (and less interesting IMO), is the difference in track setup and speed variations. Exact same track. Challenger style track--about 10 years old. 45.5 feet from start pin to finish sensor. Solenoid starting gate. THe Judge finish line. When we set the track up for Pack, one of our helpers set it up with a minimum number of pins at each track joint. If you know how Challenger tracks go together, there are two pins per lane (we have 8 lanes) that help align it. That would be 16 pins per joint. I would estimate that they used 4 pins per joint at Pack. As you can imagine, the track was rough.

Now, for Districts, we got several more pins and installed between 8 and 16 pins per joint--more when we knew a joint was particularly bad. The result was a MUCH smoother track.

Now, the empirical data. Cars that were not touched between Pack and District (all were relubed) were an average of 0.1s faster (about 5 cars for the sample size) at District than Pack. Most were almost exactly 0.1. One was 0.2 and one was 0.08s. One car that I suspect wasn't relubed (I must have forgotten to ask or someone else checked him in) improved only 0.01s. It may have been played with as well--I didn't ask.

The conclusion is that how a track is setup can make a SIGNIFICANT difference.

Now, on to the RailRiding data. My son's car was possibly the only railrider in our Pack. His speeds only improved about 0.015s. Now, we increased the drift from 3" to 4" over 4 feet and canted the DFW down, instead of up. Freshened up the wheels--switched the chipped DFW with a clean rear. Sanded off the surface and inside edge and reburnished inside edge and innner hub and outer hub. Not much to learn with that as there are too many variables to draw conclusions.

The tell-tale data comes from one of our Wolf cars--it was called White Lightning. White lightning came in 3rd in Wolf races at Pack. Average of 4.3606s over 8 runs. The Mom asked if I'd look it over before Districts and see if we can improve it. Being the Cubmaster, I was glad to help. They came over the Monday before the Districts and I checked it out. Lifted left front wheel but the car was drifting towards the DFW by about 1/4" in 4'. Rear wheels, although not intentionally canted, drifted gently out to the axle head in both forward and reverse--good rear alignment. COM was about 1.5" in front of rear axle. By rotating the DFW, we were able to achieve about 1" in 4' drift away from the DFW (DFW headed toward the rail). Much better. I explained the value of this. Next, we let it go down the alignment board with the 1.5" latte acting as the rail. Rear dominant side wheel was rubbing the rail pretty bad. We pulled the DFW (grooved axles :o ) and Dad filed off about 3/64" from the front dominant side. Rear was still rubbing so we pulled the rear out about 1/16" until it didn't rub. Now, we had a good railrider--although I felt that we'd want more than 1" of drift, we didn't want to bend the axle to get it. So, they ran it after some relubing. Now, given the track setup was better, we'd expect about 0.1s improvement. So, from 4.3606s we'd expect 4.2606s just from the track setup. Well. over the first 8 races, White Lightning averaged 4.1322s. :o :o :o That's an improvement of 0.2284s by adding rail riding--subtract the 0.1s gain from a smoother track and you still have 0.1284s gain from RR. Now, given that it was drifting the wrong way to begin with, some of that gain could be attributed to not spinning up the raised front wheel. Standard deviation improved from 0.0389 to 0.0212. That could be from the improved track surface as well--all of our boys STDEV improved at Districts--none quite that much (average about 0.01s improvement).

The conclusion on railriding on our track is a benefit of at least 0.1s on average with possibly more consistent times. I know this is only for a sample size of one but it's too large of a benefit to ignore.

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