Coriolis effect?

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Stan Pope
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Re: Coriolis effect?

Post by Stan Pope »

GimpyPaw wrote:This thread is EXACTLY why some people think there are a few of us who are a few feet shy of a short track. My wife walked by while I was reading this. She read it over my shoulder and made some incomprehensible comment about me being certifiable. :?
GP, I think that I resent the implication that I am only a few feet shy! :)

Joe,

Would your statements still be true if the car were rolling on the school's gymnasium floor?

As I understand, the apparent Coriolis force is a result of the earth rotating and gravity bending otherwise straight line path of a moving object. A stationary object is not subject to the effect. PWD cars are at their best when thay are moving. :)
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Re: Coriolis effect?

Post by M7 Racing »

I re-read my comment. You would actually want your car stearing to the right if this effect was significant enough, right?
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Re: Coriolis effect?

Post by Stan Pope »

Yes, but I wasn't going to say anything about something that was obviously a "typo." :)
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Re: Coriolis effect?

Post by Go Bubba Go »

Stan Pope wrote:DP: Not "advice" ... just a question. But you might consider asking them to move the race to Brazil. :)

The question is asked in a semi-serious vein. I don't know the magnitude of the Coriolis force, but I do know that PWD cars are sensitive and finely tuned devices. And PWD cars are deflected by much smaller forces than those which would affect the trajectory of a rocket or change the course of a hurricane. :)

As racing starts to "wind down" for the season, I thought some of the Truly Obsessed Pineheads (TOP's) would like an issue like this to mull over.
Guilty TOP here. Need to read up a bit and mull over while stuck in traffic.

Let me rephrase your question for my "thinking purposes", please let me know if I have misunderstood it.

Given that there is an effect (albeit potentially small) that will tend to drive the car clockwise i.e. to the right in the Northern Hemisphere, is it better to:

1) raise the right wheel and ride with the left, where the effect will be acting in concert with your desire to keep the left wheel on the rail (i.e. go with the flow)

OR

2) raise the left wheel and ride with the right, where the effect will be acting in opposition to your desire to keep the right wheel on the rail (i.e. fight the effect)

Is my rephrase correct, or have I missed your point?

I once read somewhere (or had someone tell me - I don't recall?) that carefully phrasing and understanding correctly the question at hand took you at least halfway down the path to finding the correct answer.
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Re: Coriolis effect?

Post by Stan Pope »

Bubba,

I think that you are correct in your desire to "pin down" the question. That is definitely helpful in finding the answer. However, I don't think that the "question" that you arrived at is the right one. To me the answer is obvious: Better that the force be with you than against you! :) If the apparent Coriolis force were with you, then you wouldn't have to expend so much of your energy to accomplish the RR.

At the time of the original post, I had not known the direction of the force, nor if it were "to the right in my local frame of reference" or if it were "eastward". I am catching up with the others who already knew that it nudged to the right.

So, I think that the question boils down now to what is the magnitude of the force in for instance Northern Illinois, and how does that magnitude compare to the force necessary to acvomplish RR?
Stan
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Re: Coriolis effect?

Post by Go Bubba Go »

Stan Pope wrote:PWD cars are at their best when they are moving. :)
Stan:

If ever a book of pithy PWD one-liners is compiled, I will suggest the above be selected for the title. LOL :D

p.s. Am I the only one who noticed you began your semi-serious inquiry at 0215 hrs? Prime TOP time.
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Re: Coriolis effect?

Post by Stan Pope »

HOOT! HOOT! Hoo Hoo Hoo HOOT!!! Yes, I am a bit of a "night owl." Especially during the past 6 months when I was a 24/7 nurse, cook, etc.

Thread-unrelated aside ... This coming week is the last week of PT for my bride. She is definitely getting feisty again. This evening she carried an armload of laundry (cane in the other hand) from the bedroom to the laundry room, set it up to wash, moved it to the dryer and got most of it out of the dryer ... all on her own! Angles are such that she can't reach far into the dryer with the limited ROM in her right shoulder, though, so she called me for help rather than hiking back to the bedroom to get her mechanical reach extender. (And I wasn't about to say a thing!) It has been a long 6 months! And, I hope that we have seen the last broken bone for a while ... a long while. I haven't been able to give away the cooking and dishwashing chores, though. :)
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Re: Coriolis effect?

Post by joe »

Joe,

Would your statements still be true if the car were rolling on the school's gymnasium floor?
Stan, I can't see why it would not. I would think that the track/car or floor/car BOTH already have the relative motion of the earth's spin applied to them -- that is, relative to the motion of the air. The air does not, as it is not attached to the earth, and has to pickup that motion or "spin" from friction against the moving earth.
If I throw a baseball for instance, that baseball already has the momentum of earth's spin attached to it, thus should not appear deflected relative to the thrower in the same way that a breeze would. However, it would be deflected relative to the atomosphere.
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Re: Coriolis effect?

Post by Stan Pope »

Joe,

Maybe you should amend the description in Wikipedia (http://en.wikipedia.org/wiki/Coriolis_effect). The writer there seems to have a rather different understanding. For instance, Coriolis effect on a thrown baseball is not absent, it is just insignificant in its effect relative, for instance, to the size of the glove that will be used to catch the ball. An unguided missile or long range shell passing through quiescent air has the same "attachments to the earth's spin" as the thrown baseball, but it moves far enough that the Coriolis effect is observable.
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Re: Coriolis effect?

Post by joe »

For instance, Coriolis effect on a thrown baseball is not absent, it is just insignificant in its effect relative, for instance, to the size of the glove that will be used to catch the ball.
A thrown ball, missile, airplane, or what have you would have the relative motion of the earth and the launcher imparted to it when it leaves terra firma. Over a long distance from a north latitude to a more southerly northern latitude, this would be negated perhaps by air resistance, but the effect would be then exaggerated by the faster movement of earth at the "landing pad" of the more southerly latitude. Point is, if I threw a baseball due south 3000 miles from Duluth Minnesota to Mexico city, an outerspace observer would see the ball traveling to the east at the same rotational speed of Duluth -- until air resistance slowed the ball's motion in that direction.

My thoughts anyway!
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Re: Coriolis effect?

Post by Stan Pope »

True, Joe, but note that you are not saying that there is no effect, just that the effect may be too small to make a difference. The relative motions, even over a short span are present but just very small.

The question at hand is whether they are so small as to be able to appear to nudge that moving PWD car's steering. I think that the effect is too small, but I haven't been able to demonstrate it yet.
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Re: Coriolis effect?

Post by Go Bubba Go »

Stan Pope wrote:Bubba,

...To me the answer is obvious: Better that the force be with you than against you! :) If the apparent Coriolis force were with you, then you wouldn't have to expend so much of your energy to accomplish the RR.

...I am catching up with the others who already knew that it nudged to the right.

So, I think that the question boils down now to what is the magnitude of the force in for instance Northern Illinois, and how does that magnitude compare to the force necessary to accomplish RR?
Interesting... In most of the discussions I have seen on the subject, and in the pictures of the cars I have seen with 1 wheel obviously lifted, it has almost always been the left wheel that is assumed (or shown) to be elevated and the right that is assumed (or shown) to do the riding.

The effect may be negligible, but it appears the default / popular setup is the "fight against it" value.

At first I thought it was an outgrowth of "right handedness", but I seem to recall that the profile of a TOP would tend to include many more left handed folks than the general population.

It would be an interesting question for the RRs among us to answer - How did you choose which wheel to lift and why?
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Re: Coriolis effect?

Post by Stan Pope »

Maybe there is a conspiracy amongst 'em, Bubba ... They got together and decided that they would keep the right side of the rail clean and smooth and let the left side do what it would. Hmmm?

Don't you love conspiracy theories? And all the wasted time tearing apart the faulty logic inherent in 'em?
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Re: Coriolis effect?

Post by Go Bubba Go »

Stan Pope wrote:Maybe there is a conspiracy amongst 'em, Bubba ... They got together and decided that they would keep the right side of the rail clean and smooth and let the left side do what it would. Hmmm?

Don't you love conspiracy theories? And all the wasted time tearing apart the faulty logic inherent in 'em?
When I have the time, it can be fun. Otherwise...

It did occur to me, though, to consider what effect rail riding has on the center rail. Assuming both sides start out in the same condition, does being ridden "improve", or does it "damage", the right side of the rail (finish, smoothness, graphite buildup?).

If it "improves" it, to some extent it would become necessary "When in Rome, to do as the Romans". The right side RRs would be "conditioning" the rail for themselves with each pass. A left side RR would not be getting the benefit of the "conditioning" performed by the rest of the racers, and would be at a disadvantage in riding the non-"conditioned" left side.

It if "damages" it, then the contrarian (left side) RR would be riding a better (i.e. less "damaged") rail and would have the advantage. At least until the others figured it out and also switched to the "less damaged" left side, at which point they would begin to "damage" the left and the right would become an advantage, at which time........ :shock:
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Re: Coriolis effect?

Post by ExtremePWD »

I predominantly use the right lane on our wood test track and it seems to have relatively improved over time compared to the less frequently used lane. No controls employed to document the change over time. We look for the new car running in the slow lane to beat the past year's car in the fast lane. :D
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