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Sidewinders - Controlling Wheel Stands

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  • Sidewinders - Controlling Wheel Stands

    The first video demonstrates the effects of free revving a sidewinder slot car with over 12 volts, using an on/off switch.

    [ame="http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=SIDEWINDERFORCEDEMO-1.flv"]SIDEWINDERFORCEDEMO-1.flv - Video - Photobucket - Video and Image Hosting[/ame]

    The second video demonstrates the amount of force, in grams, created on the front of the car by free revving a sidewinder slot car with over 12 volts, then allowing it to run at full speed.

    [ame="http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=SIDEWINDERLOADDEMO-2.flv"]http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=SIDEWINDERLOADDEMO-2.flv[/ame]

    The third video demonstrates a sidewinder accelerating at over 12 volts with the power connected directly to the motor.

    [ame="http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=12VOLTVIDEO-3.flv"]http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=12VOLTVIDEO-3.flv[/ame]

    The fourth video demonstrates a sidewinder accelerating at over 12volts with the guide in the slot and the braid adjusted flat against the bottom of the pickup.

    [ame="http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=12VOLTTRACKVIDEO-4.flv"]http://s164.photobucket.com/albums/u20/davejr-photos/?action=view&current=12VOLTTRACKVIDEO-4.flv[/ame]

    The first photo below shows how the chassis is suspended with a string at the center of the chassis, just above the center of gravity. Suspended at this point, the chassis is close to being unstable and is very sensitive to any forces.

    Placing the mounting point 1/16Ē lower, the suspended chassis was unstable and unable to balance in any direction.

    The second photo shows how the braids are adjusted, almost flat against the bottom of the guide with a slight arc. There is only 3 grams of weight added to the front of this car.

    The third photo is a composite of the third video. With the power connected directly to the motor there is nothing to stop the wheel stand. In the second and third frame the rear wheels are off the track.

    The fourth photo is a composite of the fourth video. With the car in itís normal position on the track, the power is conducted through the braids. When the braids lose contact the car stops lifting and the guide stays in the slot.

    The Slot it Ferrari 312 weighs 70 grams, 25 grams front, 45 grams rear. The right rear weighs 20 grams the left rear 25 grams.

    Dave
    Last edited by davejr; 01-20-2009, 10:52 AM.

  • #2
    Okay, I'll go first

    and ask the obvious dumb questions

    Isn't what we want - to have the power go through the braids without interruption - ie, the nose stay on the ground, to obtain maximum acceleration.

    Sooooo, waiting with baited breath for your calculations on weight placed in various positions from above the motor (joke), to on a little fishing rod 6 inches in front of the car, and everywhere in between.

    I have one of these with a yellowbell. I ended up with 9 grams weight, all forward of the front axle, front corners of the chassis; braids not quite flat, to enable what APPEARS to the easily fooled naked eye, un-interrupted power and max. acceleration.

    Depending on track surface characteristics [read amount of grip] using S2s, I can get it to barrel roll on an ultra clean, grippy track, or rear end spin if severely overcooked, but on semi-gloss surface with the S2s, it's hoking along as fast as I have been able to get it so far.

    Awaiting your further wisdom......and I am starting to turn blue in the face, so be quick.

    Comment


    • #3
      Seems to me to be too much power or too much grip. Rather than weight down the car, my 'fix' would be to more smoothly apply power, or to get some less grippy rear tires, or even a less powerful motor.

      I have a Slot.it Alfa 33 in which I put a red endbell motor and while it is blazingly fast, even down at 11-12 volts, it is also too much motor for the slower parts of the track. A standard orange end bell version is only a little bit slower and much easier to control through the slow bits. The time one spends staying on the track is worth the slower motor.

      Scott

      Comment


      • #4
        Interesting - and obvious, if you think about it - how much better the car behaves when dependent (pardon the obvious pun) on braid contact for power. I'm not sure, yet, what other conclusions to draw.

        Can't imagine sticking a yellow endbell motor in it, would seem like overkill.

        Comment


        • #5
          Point missed

          I could slow it down by putting a tourquise bell slot.it motor in it, or use dirty tyres ----surely the point of Dave's thread is greater than the obvious "if you wheelstand a short wheelbase car the braids stop connecting with the track, and you accelerate slower"

          I think anyone who has driven the 312PB knows that awfully well.

          I would presume that Dave is demonstrating the well known in his usual clinical way, and next will offer some pearls of solution, based on his great grasp of physics.

          I am thinking based around length of chassis, ratios of weight to distance from the folcrum (rear axle) and so on.

          Braids completely flat against the underside of the pickup is not an ideal solution either, because any slight tilt in the chassis or in the track surface means loss of contact at times you DON'T want to lose contact, and thus lose power or braking.
          Tracks with sharpish undulations are deathly for cars with pressed flat braids.

          The reason for a yellow bell in my case is simply track/racing rules situation in which I will be driving it, and what it has to run against, but it did the nose dance equally well with a stock orange bell on my home track. In fact I could pop it out of the slot very easily.

          "Applying power more slowly" is not logical when you are trying to go fast. Show me the man with a 100 step controller, and the reactions and eye-finger coordination to lift the voltage perfectly, and quickly contract him to an F1 team......

          In this case, on my home track, which has only one 10 foot straight and a 7 foot one, plus 6 turns esses, and a reverse flick in 60 feet, but I knocked lap times for it down from 6.3 as stock, to 5.8 by using a yellow bell geared down to obtain better punch and braking, and adding said lead.

          I haven't got around to the fancy stuff yet, but that gives an indicator of the value of the lead. The motor, based on other longer wheelbase cars I have repowered, was good for 0.15 of the improvement, the lead 0.35, by allowing the power to be utilised.

          Comment


          • #6
            I have found that adding any weight to a Slot it car reduces the cornering speed on my track. For this reason I donít add any weight to them.

            The Ferrari 312 used in this demonstration has a 20 watt motor and a 3.09 gear ratio. This car holds the track record for fastest lap time, fastest acceleration on the ten foot drag strip, and fastest skid pad times. The car will run the same times with the 3 grams removed, I installed the weight originally for handling.

            I set up all my cars with the softest braids (SP 05) and they are adjusted the same way as shown for the Ferrari 312. I have never had a car de-slot from a wheel stand in normal racing conditions.

            With a clean track and the front wheels on the track surface, the cars never lose contact with the tape, lose power or braking.

            Dave

            Comment


            • #7
              I tested the Ferrari 312 again the see what effect added weight would have on this carĎs acceleration.

              With the three grams of extra weight added to the car, these are the elapsed time and speed for ten foot acceleration @ 10 volts.

              0.694 sec. @ 15.47 mph

              With the three grams removed.
              0.695 sec. @ 15.54 mph.

              With ten grams added to the nose on the number 85.
              0.689 to 0.698 sec. @ 12.88 to 14.86 mph.

              With the extra ten grams of weight, the car was spinning the tires at the finish line causing the drop in top speed.

              On the Magnet Marshal.

              With the three grams of added weight, the car weighs 70 grams, 25 front, and 45 rear.
              With the extra ten grams added in front of the front wheels, the car weighs 80 grams, 40 front, and 40 rear.

              Other cars tested.

              R&D Jaguar.
              0.682 [email protected] 16.29 mph.

              Schiesser 956K stock orange motor.
              0.748 sec @ 13.36 mph.

              Dave

              Comment


              • #8
                Same but different

                for lack of a cuter saying. Thanks for that info. Dave, it just shows how different cars have to be set up different for each track.

                On my track, the stock 312PB is about 6/10ths slower than a McLaren or Nisan, which in turn are quicker than the "non-offset" cars, like 956, Lancia etc.

                The Ferrari WAS almost slowest of the Slot.its, and on a par with an NC-5 powered Ninco GT (that had been well set up)

                My goal, to make it run with the "out of era" quicker cars.

                I don't recall the surface of your track, mine is semi-gloss acryclic (water-based) clear usually used for glossy wood flooring; over acrylic (latex) paint.
                It is a silicons track - urethanes do okay, but silicons stick like glue.
                The old "push it sideways" trick to check grip, can actually pull tyres off the rims unless you glue them on.

                Because of that, I can make a stock 312pb wheel stand at part throttle, just flick the controller triggeer quickly, and pop it straight up out of the slot if I don't add weight to the nose.

                Haven't got round to de-boxing an Alfa yet, I suspect that will be similar.

                If I ran urethanes on the same car, my track, I probably wouldn't need to bother using weight, unless I was using very small amounts, trying to re-balance front to rear, and make it a little less tail happy.

                Wet, you remember commenting on the high speed we could carry round the sweeper at my track..... that was early days, 6.5 - 6.7 seconds laps you were seeing on that video. We now run same cars at around 5.7 - 5.9 laps, just with clean track, better setup cars.

                Now, back to tuning my new baby.... the Boutsen/Bellof Shiesser 956K from 1985.......
                resisted taking this one out of a box for months......then watched the video Group C tribute just once too many today........ DANG that is a wonderful car and proud history. ...and sad ending at Spa......

                Comment


                • #9
                  Originally posted by SlotsNZ View Post
                  I don't recall the surface of your track, mine is semi-gloss acryclic (water-based) clear usually used for glossy wood flooring; over acrylic (latex) paint.
                  It is a silicons track - urethanes do okay, but silicons stick like glue.
                  The old "push it sideways" trick to check grip, can actually pull tyres off the rims unless you glue them on.

                  Because of that, I can make a stock 312pb wheel stand at part throttle, just flick the controller triggeer quickly, and pop it straight up out of the slot if I don't add weight to the nose.

                  Haven't got round to de-boxing an Alfa yet, I suspect that will be similar.

                  If I ran urethanes on the same car, my track, I probably wouldn't need to bother using weight, unless I was using very small amounts, trying to re-balance front to rear, and make it a little less tail happy.

                  Wet, you remember commenting on the high speed we could carry round the sweeper at my track..... that was early days, 6.5 - 6.7 seconds laps you were seeing on that video. We now run same cars at around 5.7 - 5.9 laps, just with clean track, better setup cars.

                  ..
                  From this post it sounds like we race on almost identical tracks. All I have to say is pull that Alfa out of the box. I run my 312pb with quite a bit of weight added, but to my amazement, the Alfa required NONE. And its about a 1/10th faster around my track, could be due to the fresh motor though.

                  Comment


                  • #10
                    Being an obedient little slotter

                    I pulled that Otto Zipper out of his wrapper, and did a couple of laps....


                    ...okay, I did a couple of hundred laps....

                    yes, I was surprised at the difference. I had expected performance nearly identical to the Ferrari, as they were built to run together, ad the wheelbase, track ad shape are pretty similar. But like you, I found I can run it with no weight, and it is 1/10th quicker stock than the Ferrari after "work" and a LOT faster than the Ferrari was stock.

                    Mind you, still 2/10ths slower than the 956K after a pod relief and braid upgrade (softer braids)
                    Enoyable to drive, but still requiring more concentration than the long wheelbase group Cs.

                    More tuning tomorrow, the riesling and Lao food have me quite mellow, so this advert break at the PC must end.
                    Last edited by SlotsNZ; 11-14-2008, 01:08 AM.

                    Comment


                    • #11
                      My track surface is semi-gloss finish Sears latex paint that is sanded and polished.

                      This car was used in a previous article where it demonstrated that it could lift 78 grams of weight on the front wheels the instant power is applied.

                      To control this lifting force you can add weight, or as I did, limit the power by using the braids as a governor. The small amount of acceleration that is lost by governing the power is more than made up by having less weight to accelerate.

                      The added weight also lowers the cornering speed when using S1 or S2 tires by quite a bit. Adding 5 grams to the center of this car lowered the skid pad times by 0.060 seconds.

                      The Alfa Romeo that I did the article on, ran 7.2 second laps with just basic race preparation, S2s and too low of a gear ratio. The cornering speed was a little slower than the 312s, but the lack of top speed limited itís lap times. With the S1 tires and a 2.83:1 gear ratio it would run laps in the 6.7 to 6.8 second range.

                      The Ferrari 312 with a 20 watt motor holds the track record at 6.473 @ 15.9 mph.

                      Dave

                      Comment


                      • #12
                        curiosity

                        Thanks for the info. Dave.

                        I'm curious, do you have a pic of your track we could see. How long is your track?
                        Interested in the layout and length.

                        15.9 MPH sounds snot fast if that figure is an average lap speed, that's 23.3 feet a second.
                        We can't get a magnet sled around plastic with a hot motor any quicker than that, so I am assuming that is a max speed at some point through a straight section with sector timing?

                        The old benchmark I always used was for small tracks, anything over 10ft a second average lap speed was either a quick track design, or a quick car, and for medium sized club tracks, maybe 12 - 15 feet a second depending on design, tyre choices etc.
                        (all non-magnet of course)

                        My unloaded rear wheel speed for a slot.it sidewinder 20.5 tyres with red-bell motor and pulled down for torque and braking on the small track to 9/38 gearing is about 20 MPH flat out.

                        My lap record is just under 5.3 seconds for 61 feet, which is 11.5 feet a second, (8MPH average lap speed), and I thought that was moving fairly quickly for sillies on a small woodie.
                        Last edited by SlotsNZ; 11-14-2008, 07:22 PM.

                        Comment


                        • #13
                          I have to ask ...

                          15.9 MPH sounds snot fast if that figure is an average lap speed, that's 23.3 feet a second.
                          ... just how fast is the snot in your part of the world?

                          Comment


                          • #14
                            The 15.9 mph is the actual speed the car is traveling that is measured in the speed trap at the 8 to 10 foot distance on the main 16 foot straight.

                            The fastest mph ever recorded in the speed trap on my track was 20.45 mph.

                            The track is 79 foot long and the average speed for the 6.473 record time is 12.2 f/second or 8.32 mph.

                            Dave

                            Comment


                            • #15
                              Originally posted by SlotsNZ View Post
                              . . .
                              The old benchmark I always used was for small tracks, anything over 10ft a second average lap speed was either a quick track design, or a quick car, and for medium sized club tracks, maybe 12 - 15 feet a second depending on design, tyre choices etc.
                              (all non-magnet of course)
                              . . .
                              My lap record is just under 5.3 seconds for 61 feet, which is 11.5 feet a second, (8MPH average lap speed), and I thought that was moving fairly quickly for sillies on a small woodie.
                              Coincidentally, I have a 61 foot wood track, with a 16 foot main straight. I run at 13.6v, and the best dry-tire lap time is by an RAA car (Smokeio's Saleen) at 4.458 sec. That car had a Slot.It Boxer 24 motor, anglewinder Slot.It McLaren chassis, and Super Tires "Classics" (silicone). Well-tuned Slot.It cars can lap in the 4.6 range (with Super Tires). Smokeio's Saleen has an 8.1 watt motor. Generally, extremely powerful cars are held back by their excess torque, as they are difficult to drive through the corners on the voltage I use. The surface is not particularly high grip (Benjamin Moore rolled interior flat latex, no sanding, just run-in), and cars rarely de-slot due to wheel-stands. The typical maximum lap speed, at 4.65 sec/lap, is 13.1 feet/sec.

                              Cars with NC-1's will lap at 10 fs (6.1 sec laps).
                              Last edited by Robert Livingston; 11-15-2008, 02:30 PM. Reason: 5.458 was supposed to read 4.458

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