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Sauber Mercedes C9 Sidewinder, Part 2 Conclusion

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  • Sauber Mercedes C9 Sidewinder, Part 2 Conclusion

    I ran a direct comparison with a new car to see how much better a sidewinder chassis is than an inline chassis. With all of the talk about sidewinder and angle winder chassis arrangements, I thought there should be a noticeable improvement over an inline chassis.

    The Sauber Mercedes C9 has to be the best Slot it car I have ever run. Out of the box with new S1 tires and a little body tweaking it ran the fastest laps for a C1/Prototype car on my track.

    The conversion to sidewinder was simple and straight forward. The car ran impressively smooth and appeared extremely fast. After running over 900 laps in the sidewinder configuration, the car broke itís own inline lap times.

    Before I changed it back to the inline set up, I tested it on the skid pad to see if itís times had improved.

    I also tested the sidewinder and inline setup on the chassis dyno to see if there was any difference in performance.

    These are the results of the chassis dyno tests.
    InlineÖÖ 251 g/cm Ts, 31225 maximum RPM.
    Sidewinder 247 g/cm Ts, 32145 maximum RPM.

    The performances listed below are the best results for each motor set up, with the best performing gear ratio and chassis tuning for each.

    After running over 900 laps with the sidewinder setup these are the best average times for this car.

    Skid Pad CW 0.781, CCW 0.771 seconds.
    Race Track lap times with 3.27:1 gear ratio
    Average of 10 fastest laps 6.675 seconds.
    Fastest lap in both lanes 6.613, and 6.610 seconds.
    Top speed 16.35MPH


    After the sidewinder tests, the car was changed back to the inline chassis setup, the original C9 rear wheels were installed and the car was run another 200 laps.

    These are the best average times for the inline car with a 3.50:1 gear ratio.
    Skid Pad CW 0.729, CCW 0.741
    Race Track lap times
    Average of the 10 fastest laps in both lanes 6.625 seconds.
    Fastest lap in both lanes. 6.556 and 6.563 seconds.
    Top speed 15.64MPH

    The Sauber Mercedes C9, back in the original inline set up and with very little tuning, now holds the track record for my race track.


    Dave
    Last edited by davejr; 09-17-2008, 06:23 AM.

  • #2
    Why did you change the gearing to 3.50:1? I read your other thread and I don't understand why you added 1gram of lead to the front of the car when switched to the sidewinder configuration. That's defeating the purpose of the test because you're changing one of your constants.

    I'd believe the gearing had more to do with the record breaking lap rather than the motor orientation. Not trying to offend you, but are you really getting the "most" out of each setup when you drive them?

    I'm just wondering because your conclusions go completely against my experiences. I recently replaced the inline pod in my C9 and placed a sidewinder in its place. With the same motor and similar gearing, the sidewinder configured C9 is more predictable, like you said, has more out of the corner grip, like you said, and can be pushed a lot harder. This resulted in a .4second faster lap in the big Ninco track and .3 in my home track. My home track being a short, technical 20ft track while the big track having a 70ft straight and super long.

    No matter the track configuration, the car was simply more predictable, easier to drive, and had a more comfortable "turn-in" characteristics compared to the inline. It could be driven in deeper and accelerated earlier.

    I believe that's what timkoul was trying to point out to you. Your skid pad readings simply show how the car will do in the "middle" of the turn. I believe to get the advantage out of the sidewinder configurations is going to be up to the driver to take advantage of its better corner entrance and exiting capabilities.
    Last edited by Mark; 02-21-2008, 09:25 AM.

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    • #3
      Originally posted by Mark View Post
      Why did you change the gearing to 3.50:1? I read your other thread and I don't understand why you added 1gram of lead to the front of the car when switched to the sidewinder configuration. That's defeating the purpose of the test because you're changing one of your constants.
      I agree, Mark. The idea behind comparative testing is to isolate changes to a single characteristic, and observe the results. If 1 gram of lead needs to be added to the sidewinder in order to make it driveable (or for any other reason), then 1 gram needs to be added to the inline as well. 1 gram changes the weight of the car by 1.33%, and makes an even bigger swing in weight distribution. When the difference in average lap times is only 0.75%, that can easily be attributable to a change that's entirely unrelated to the configuration. And that's not even touching the gear ratio change, which can have monumental effects.

      Not knocking your effort in any way, Dave -- we're fascinated by what you're doing, and always looking forward to your results!

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      • #4
        In the first article about the Sauber Mercedes C9 I said that the sidewinder drove smoother in all aspects and appeared to be faster.

        The inline car weighed 75 grams the sidewinder weighed 74 grams, I added the 1 gram so both setups had the same total weight. The sidewinder still had 2 more grams on the rear tires.

        I geared and tuned both setups to get the best performance that I could out of each.

        The 10/34 gearing only slowed the sidewinder setup over the 11/36 gearing. It became more erratic in the turns and acceleration from the turns, and didnít improve the braking.

        The change from 3.25:1 to 3.50:1 only improved the braking, all other aspects remained the same with the inline setup.

        Maybe if I used rubber tires on my track there might be an advantage to the sidewinder setup.

        After spending the money to do this test I was hoping for some improved measurable results.

        The Sauber Mercedes C9 is my R&D toy, and it has replaced my worn out Bud Light Jaguar. I am continually trying to improve the performance of these cars and lower the overall track record with it.

        Dave

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        • #5
          Guys, I understand what you're saying about changing only one variable at a time to make valid comparisons, and generally I would agree with you. In fact, when I first saw this, I thought the same thing. But as I think about it a bit more, I have to go with Dave on this one.

          Although it might also have been instructive to see the lap times for equal weights and gear ratios, if one configuration has better chassis balance without adding weight, then a valid comparison of the two configurations should reflect the weight difference. And if one configuration allows better grip out of corners and can handle more power, then a valid comparison of the two configurations should also reflect the optimum gear ratio for each one. You can't evaluate the total advantage of each configuration without optimizing each one.

          And finally, the closeness of the results and Mark's findings that somewhat contradict Dave's, show the inherent fallacy of drawing too broad a conclusion from too narrow a sample. I think it also shows that there really isn't as much difference between the two configurations as some people think, and a lot of the perceived advantage of either is just due to individual preference or driving style.

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          • #6
            Yes and no, Jim. If you're comparing chassis balance, then you absolutely can't make up for one car's deficiencies without doing the same for the other.

            But what you're saying leads us down what I think is the correct path -- that several configurations need to be tried for both the sidewinder and inline, because what's optimum for one may not be optimum for the other.

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            • #7
              Kurt, most would agree that a front-motored car is at a disadvantage when compared to a rear inline car. You seem to be implying that a front-motored configuration, which needs significant weight added for best balance, can only be compared to a rear inline configuration when you add unecessary weight to the rear inline car to make the total weight equal? I disagree with that. The rear inline configuration has an inherent advantage because it doesn't require additional weight for proper balance. If you make them equal in weight, you nullify the advantage of that configuration and the comparison becomes moot. (Or maybe just moo, who knows?)

              As I see it, the same approach should be used for a rear inline vs. sidewinder comparison. The rear inline car has an inherent weight advantage because it is better balanced. Any valid comparison of the two configurations must take that into consideration.
              Last edited by Zoom Beedo; 02-21-2008, 10:01 PM.

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              • #8
                Originally posted by Zoom Beedo View Post
                Kurt, most would agree that a front-motored car is at a disadvantage when compared to a rear inline car. Are you saying that a front-motored configuration, which needs significant weight added for best balance, can only be compared to a rear inline configuration when you add unecessary weight to the rear inline car to make the total weight equal? I disagree with that.
                No, that's not exactly what I'm saying. I'm saying that in order to be complete, it'll take more trials. It's probably fair to say that there's an optimum place to add lead in an inline and in a sidewinder car.

                First trial -- no lead added to either car
                Second trial -- 1 gram added to each car's 'sweet spot', wherever that may be
                Third trial -- 2 grams added to each car's 'sweet spot'

                Keep adding weight and running them. Both cars will reach a peak of performance, then start to fall off. This does not necessarily happen during the same trial, but when you are done, you can compare peak performance vs. peak performance.

                How does that sound?

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                • #9
                  I agree with Dave' s testing conditions. One that prepares a car for club racing, would like to tune it to the optimum extend of a given configuration. If an inline is faster with a 3.5 ratio and a S/W is better with 3.25, then he should choose the appropriate ratio on both circumstances. Same applies to the weight. I too, like the inline cars, because I can easily change the rear track without looking for washers, and I can run tires as low as I need to. But the fact remains that, on our track the S/W car was significantly faster.
                  What rings a bell here is that, Dave did not use rubber tires. On practice sessions, I noticed that, as traction builds up, the I/L setup gets closer to the S/W. Maybe it has to do with the available amount of traction.
                  Still the difference in layouts and driving styles, is the most important factor I think...

                  Comment


                  • #10
                    Originally posted by ElSecundo View Post
                    ...How does that sound?
                    Sorry I misread your statement, Kurt. That sounds like a proper application of the scientific method, just what's needed for an evaluation of this type (although, not the preferred methodology of our government lately - where's that tongue-in-cheek icon?).

                    I suspect, though, that Dave performed a lot of these trial iterations in arriving at the configurations he tested, but just didn't burden us with all the interim data.

                    Comment


                    • #11
                      Originally posted by Zoom Beedo View Post
                      I suspect, though, that Dave performed a lot of these trial iterations in arriving at the configurations he tested, but just didn't burden us with all the interim data.

                      I think you're right, Jim. I just don't think that I can take it at face value that 1 gram behind the guide on the inline, while adding no weight to the sidewinder are 'optimum' configurations. If they have shown themselves to be the best possible setups for both, then it's a good test, but they HAVE to be the best possible setups in order to be a valid test. Otherwise, the only fair test is no weight for either car, or identical weight for both cars.
                      Last edited by ElSecundo; 02-22-2008, 07:29 AM.

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                      • #12
                        Hi Jim, Kurt, Dave, and everyone,

                        I am partial toward Dave's testing methods and results so I cannot make a proper judgement as to whether Dave's methods were scientifically correct. Actually, to be scientifically correct, the scientific method must be employed. First, the person performing the test makes a postulation that " The Sidewinder motor configuration will produce no noticable improvement in performance."

                        Second in applying the scientific method is to gather baseline data on the car with an inline motor configuration. Third, the car should be converted to a sidewinder config and data obtained in order to compare the results. Placement of the weight can have a huge impact on the performance depending on where it is placed, however, if the weight is placed in front of the front axle, the only effect you will see is that it will keep the nose pinned to the track. It should not affect performance. I observed this in person while reviewing the Fina McLaren.

                        Having performed tests with Dave and sharing data via SCI and email, I can say without a doubt that Dave's testing is ALWAYS very thorough. Once he and Robert Livingston start trying to explain the math and physics, I get lost.

                        As for Dave's re-gearing of the car, I have had the same experience. We run Group C cars with the stock Slot.It mag. I have found that the best gear ratio on my track is 9:26. Since I am in the process of testing and learning to drive 2 Slot.It 956's for the Alabama vs. Georgia race meet, the 9:26 ratio left me with terrific straight line speed but virtually no brakes. I changed to the red crown gear, resulting in a 9:30 ratio. All of a sudden, straight line speed droped, however, the car was faster through the corners and upon exiting the corners without changing any weight placement. Perhaps that is why Dave changed the gearing.

                        Anyhoo.......cool thread with loads of good information. What would be a great project is for each of us to have one of the new C9's and we all conduct the same test as Dave has on our own tracks to see how this would affect the car in different configurations.
                        Anyone up for this idea?

                        KIITS,
                        Lawrence

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                        • #13
                          A little more clarification is needed.

                          One gram was added to the sidewinder to make both chassis setups weigh 75 grams.

                          33/42 inline and 31/44 sidewinder.

                          There is no way to get the front to rear ratio the same without adding more weight, which will only slow the cornering speed for both chassis setups.

                          The motor used in this test works best with a 3.50:1 gear ratio, which isnít available in sidewinder. The only close gear sets, close to what I needed, are the 3.25:1 and 3.27:1 ratios.

                          The fastest lap with the 3.25:1 gear set was 6.634 seconds.

                          The fastest lap with the 3.27:1 gear set was 6.613 seconds.

                          The fastest lap with the 3.40:1 gear set was 6.575 seconds which I didnít use because I couldnít back it up. I like to have at least 5 laps within 1% before I accept it for a fastest lap. For some reason the car was very erratic with the 3.40 gears and the best fastest laps were in the 6.675 second range.

                          When I changed the car back to inline with the 3.25:1 gear set, the fastest laps were in the 6.620second range.

                          With the installation of the 3.50:1 ratio the car was in itís best performance range, acceleration, braking, maintaining itís cornering speed, and top speed.

                          If I had a 3.50:1 sidewinder gear set I am sure that the sidewinder and inline lap times would have been close.

                          The only difference that I found between the inline and sidewinder setup was the sidewinder gear sets are much smoother and make the car all around easier to control.

                          The biggest difference with the sidewinder is the weight on the rear tires. When the weight on the rear tires is over 40 grams the cornering speeds start to slow.

                          The inline set up is a little noisier and creates a vibration when slowing from top speed.

                          As far as overall performance I think it is to close to call, and again the results are just for my track and my car set ups.

                          Dave
                          Last edited by davejr; 02-22-2008, 08:14 AM.

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                          • #14
                            Originally posted by davejr View Post
                            One gram was added to the sidewinder to make both chassis setups weigh 75 grams.
                            Excellent, thanks Dave. In that case, would you agree that the best place to add the weight (to equalize the testing) would be at the center of mass of the car, rather than behind the guide?

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                            • #15
                              What I would prefer to do is remove weight to get both chassis setups at 31/40, the only way to do this is to start grinding out the body. This setup usually proves to be the fastest weight for a Slot-it car with S1 tires.

                              Dave

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