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So Much For The Theory About Cornering Speed!

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  • So Much For The Theory About Cornering Speed!

    How much does the cornering speed effect the speed on the next straightaway?

    I was running a few laps testing some changes to my Sauber C9, and watching the top speed continue to increase as the motor warmed up.

    I recalled a discussion here about the cornering speed having a great effect on the top speed of a car.

    Ever since I have had the ability to measure the top speed at the start/finish line, I have wondered about this effect.

    The start/finish line is 8 foot 6.5 inches from the previous turn. The speed trap ends 2 foot past the start/finish line.

    The cars are approaching the main straight from two different radius turns, therefore different cornering speeds, but the carís top speed is the same in both lanes.

    When the C9 was warmed up it had increased itís top speed, at the start/finish line, to 20.5 f/sec in both lanes.

    To try to understand this effect, I stopped the car at the eight foot mark, the distance to the start/finish line, and ran an acceleration test in both lanes.

    The acceleration testís top speed in both lanes at the start/finish line was 20.5 f/sec from a dead stop, the same as the top speed coming on to the straight at maximum cornering speeds.

    I decided to try this experiment with one of my slower cars, the Porsche 911GT2. After a dozen laps itís top speed was 14.7 f/sec.

    I ran the same test stopping at the eight foot mark, same results in both lanes,14.7 f/sec from a dead stop.

    Next came my big gun, the R&D Jag. After ten laps the speed was 24.1 f/sec.

    I ran the same experiment again, stopping at the eight foot mark, and again the same results in both lanes, 24.1 f/sec from a dead stop.

    The R&D Jaguar, running on the 20.5Ē diameter skid pad, has a top speed of 7.9 f/sec.

    The same car travels through the 30.5Ē diameter inside lane 1 at a maximum speed of 9.7 f/sec.

    The same car travels through the 38.5Ē diameter outside lane 2 at a maximum speed of 10.3 f/sec.

    The photo shows the corner where the exit speed was measured. The dark grey area is a two foot speed trap set up to measure the corner exit speeds

    CONCLUSION.

    To answer the original question with all of this test information, the only conclusion I can make is that the cars are at their maximum speed some distance before the start/finish line and the cornering speed doesnĎt effect the carís top speed at the start/finish line.

    All the cars in these tests are geared for their best lap times, I believe the cars are reaching their maximum speed a lot sooner than I thought.

    A previous test I did about adjustable braking, bore this out. I used the 8 foot front straight where the speed trap was at the 4 to 5 foot distance from the previous 24Ē radius turns, and the Jaguar was already at 95% of itís maximum speed.

    This is a link to that test.

    http://slotcarillustrated.com/portal/forums/showthread.php?p=185569#post185569

    Dave
    Last edited by davejr; 09-15-2008, 05:44 AM.

  • #2
    That's very interesting , Dave.
    More great stuff/facts.

    ......now how can I fit a 2-speed auto trans in my C9 like my R/C truck has? ...mmmmm......

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    • #3
      Tried the two speed drive back in the 60s on a drag car. When I finally got it to work, it was outlawed.

      Dave

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      • #4
        One of these days, Dave, you are going to have to enter a proxy race so we can see the research in action, in a car, in a race. How about it?

        Comment


        • #5
          I agree with the conclusion: Cornering speed does not affect top speed.

          BUT, Cornering speed affects how soon a car reaches its top speed on a straight after a turn. More cornering speed = the faster the car is already going through a turn, therefore less acceleration needed to reach top speed on the striaght, which translates to quicker lap times.

          This statement says it all:
          To answer the original question with all of this test information, the only conclusion I can make is that the cars are at their maximum speed some distance before the start/finish line

          And I second Robert. I think you'd have fun entering a proxy race, dave.

          Comment


          • #6
            Originally posted by Mark View Post
            I agree with the conclusion: Cornering speed does not affect top speed.

            BUT, Cornering speed affects how soon a car reaches its top speed on a straight after a turn. More cornering speed = the faster the car is already going through a turn, therefore less acceleration needed to reach top speed on the striaght, which translates to quicker lap times.
            Exactly.

            Let's say we have a 12 foot straight, and we'll look at 5 points on the straight.
            Point A -- exit from the curve
            Point B -- 3 feet from exit
            Point C -- 6 feet from exit
            Point D -- 9 feet from exit
            Point E -- 12 feet from exit

            Cars #1 and #2 exit the curve at point A, #1 at 6 f/s, #2 at 8 f/s.

            At point B, both have accelerated an additional 2 f/s. Car #1 is at 8 f/s, car #2 is at 10 f/s.

            At point C, both have accelerated 2 more f/s. Car #1 is at 10 f/s, car #2 is at 12 f/s.

            At point D, car #1 reaches 12 f/s, and car #2 tops out at 14 f/s.

            At point E, car #1 tops out at 14 f/s, and car #2 holds at top speed, 14 f/s.

            Car #2 has a greater instantaneous velocity than car #1 at every location on the straight, right up until point E. The two cars have identical top speeds and identical torque/acceleration, but car #1 is losing ground throughout the entire straight until reaching point E, because it has a lower instantaneous velocity at every single point along the straight.
            Last edited by ElSecundo; 09-15-2008, 07:36 AM.

            Comment


            • #7
              I have been watching A grade drivers and cars and where the best tuned cars pick up time from the others and other than deeper braking etc which is variable from lap to lap but the good drivers seem to hit the brake spots more consistently. My thoughts are that is has more to do with the cars stability and the cars ability to exit the corner quickly that gains the most time. That is a combination of grip car setup and maybe a little of corner speed but many good drivers seem to "drive it straight" and are very on /off on the throttle. slot cars hit maximum speed very quickly as a rule but every little tiny waggle or slide on exit costs time. As my brother says grip = go slide = slow.

              Comment


              • #8
                A wise man once said he never won a race with a motor, but lost many races in the corners. Or something like that.

                I have no difficulty building cars which go faster than they have any business going on the straights, but I do have difficulty increasing the cornering speed of my cars. If you spend, say, two thirds of the time negotiating corners, and one third of the time on straights, which is more important? The answer is obvious. As long as you can build a car that has adequate speed on the straights (usually accomplished by using the right motor for the class), the race is won or lost in the corners.

                Comment


                • #9
                  Originally posted by Robert Livingston View Post
                  A wise man once said he never won a race with a motor, but lost many races in the corners. Or something like that.

                  I have no difficulty building cars which go faster than they have any business going on the straights, but I do have difficulty increasing the cornering speed of my cars. If you spend, say, two thirds of the time negotiating corners, and one third of the time on straights, which is more important? The answer is obvious. As long as you can build a car that has adequate speed on the straights (usually accomplished by using the right motor for the class), the race is won or lost in the corners.
                  Yes, but when you gain in the corners, you're also gaining on the subsequent straights. You not only gain in the 2/3 of the bent track, you gain in the 1/3 of the straight track. Cornering is the gift that keeps on giving...

                  Comment


                  • #10
                    Your title is a little misleading. Back in my 1:1 racing days, my driving instructor taught me to look at a road course like a series of drag strips. The goal of of corner was to exit at the highest possible speed so the time down the straightaway would be the shortest, like a drag strip. I drove a slow Ford Fiesta and though I never had much for top speed, I could always pass a faster top speed car by passing them coming out of the turn. They would be running at a faster top speed at the end of the straight but I got to the next turn first because I was going that much faster exiting the turn.

                    Racing a slot car is the same thing, the higher your cornering speed the sooner you get to your top speed and the "quicker" (time wise) you get down the straight away. This of course depends on the length of the straight away. Some of us that have tight home course many never see the actual top speed of the car.

                    In any case, cornering speed means everything. It does impact the amount of time your car gets to the top speed which in turns has a big impact on your lap times. When you are racing slot cars, lap times is what it is all about.

                    Comment


                    • #11
                      Originally posted by Smokeio View Post
                      Racing a slot car is the same thing, the higher your cornering speed the sooner you get to your top speed and the "quicker" (time wise) you get down the straight away. This of course depends on the length of the straight away. Some of us that have tight home course many never see the actual top speed of the car.

                      In any case, cornering speed means everything. It does impact the amount of time your car gets to the top speed which in turns has a big impact on your lap times.
                      Exactly, Mike. The only way exit speed doesn't affect the straight speed is if all cars accelerate to top speed instantaneously, which we all know they don't do. The longer it takes cars to accelerate to top speed, the more critical the exit speed is.

                      Can't emphasize it enough, really.

                      Comment


                      • #12
                        Hi

                        The critical number isn't the top speed but time spent on the straight. Remember you must slow for the next corner. Treating each part of the track in isolation doesn't illustrate the important parts.

                        Simply, time.... and ease of doing those times. The second is actually the more important point. How consistant are your lap times with a given set up. A car with a slower time is still a winner if you can hit that time every lap and the car is so comfortable that you run at your qualifier every lap.

                        Most cars can be expected to run consistantly for a race within 5% of its best time, a great car does within 1 or 2.

                        Fate

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                        • #13
                          Dave,

                          It would be great if you could gear the car so it has a higher top speed and repeat the tests. As long as the car needs more than 8 feet to reach top speed, you will better be able to see the results of cornering speed.

                          Best regards,
                          Brian

                          Comment


                          • #14
                            More interesting input from DaveJr, & a new Forum!

                            This certainly tells us a lot about the power-to-weight ratio of slot cars, and their remarkable acceleration. In a 1:1 car, as others have noted here, fastest time around a track is always going to be achieved by carrying the fastest exit speed out of a turn, thus spending the greatest amount of time at full throttle - with the result of highest maximum speed - on the straights.

                            One thing most of us have realized when racing slot cars is that the tidier you are coming out of a turn (i.e. no tail wagging) the sooner you can nail the power into the straights, and the quicker your lap times will be.

                            Meanwhile, sharp eyed observers may have noticed that Dave Jr's many and various well researched Threads of this type have now been collected and transferred to their own Forum, "Dave's Slot Car Tips". It's quite a collection of data, and much appreciated here on SCI.

                            Comment


                            • #15
                              Good job guys. I think it was a great idea! Dave truly deserves his own forum.

                              It's great to see someone so enthusiastic about proving theories and such experimentally for all to see. While some may know the outcome of the experiments before they are even performed (whether it be by experience, knowledge, or being Einstein's relative), many do not, and I think Dave has been a great benefit for many.

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