假若直路尾髮夾彎反車你會選用…(可選多項)

I can understand what you are driving at. I do agree that RC is a kind of "Chaotic Science" that involves a lot of uncertainties and element of luck, but I believe there are still a lot of 'truths' and formula that we can rely on and save our time.

Sometimes we don't always have to try out something by ourselves. Doing a survey like this sometimes helps. We can gain knowledge from others' experience. Afterall, knowledge is collaborative.
billy86che 發表於 2009-5-14 00:26

                               
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survey comes up with a common view not a theory.
a large amount of people elected a president does it means he/she is perfect?
I have no air to play with an ox skin lantern with text, discuss with you on track~

The charts show the view but the talking can show some theories, don't you agree?

By the way, I look forward to seeing you every Friday.

I put it this way, given the highest grip tyre all round of the same width,
other factor being CONSTANT (need to be rational of course), 2 major
factors contribute to the relation of spring-tension and
chance-of-traction-roll are:

1. Track width to CG ratio
2. Droop

The lower the above 2 value, the greater the chance of traction roll. It is
because they have different number of spring to choose from. Considering
there is a window of spring choice, different combination of the 2 value
adjust the window (size and location) of spring choice.

In graphical terms:
Hard(Solid)　　　　　　　　　　　　　Soft
|-----------[　window　]---------------|

For instance, a double decker bus (with default high droop value already), its window lies on some where here. Will a bus with solid suspension flip? no doubt.

Hard(Solid)　　　　　　　　　　　　　Soft
|--------[window]----------------------|

For a F-1 (ultra high Track width to CG ratio), its window like this.　Will a F-1 with solid suspension flip? I guess so.

Hard(Solid)　　　　　　　　　　　　　Soft
|-[　　　　w　i　n　d　o　w　　　　]-|

Do you agree my points?
The above is just my 2 cents, not a theory.

But it seems that you have not considered one very important factor on the difference between the bus and the F1, which is the distance between the roll centre and the CG. For a bus, the CG is certainly higher than the roll centre, but for an F1 they are very close to each other (CG can even be lower than the roll centre if your suspension system allows).

I suggest other than CG & width, you also have to understand the 'roll centre'.

Next, my hypothersis is that, provided a harder front spring, rolling is reduced and so is the traction, and that causes less steering and thus lower the possibility of a flip over.

One possibility of why you found softer front springs cause less flipover in your driving experience may be you change to a pair of softer springs without maintaining the same ride height. If you just change to softer springs, the ride height is certainly lowered (I hope you had not over preloaded your springs too much to the extent that your car did not droop) and thus lowering the CG and then the possibility of a flipover.

Tell me, when you changed the springs, did you readjust the shimming (shims) to KEEP the ride height you were running with?

I can understand what you are driving at. I do agree that RC is a kind of "Chaotic Science" that involves a lot of uncertainties and element of luck, but I believe there are still a lot of 'truths' an ...
billy86che 發表於 2009-5-14 00:32

                               
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非常同意, 遙控車甚至四驅車 都和 真車一樣, 是複雜的物理結果, 問題只在於我們沒有明白其中的知識和觀察力

use 40  front and 10 rear and try la.

by the way, if you only think about a part of the track, it is useless. see whole picture better than a small part of it.

I dont have professional knowledge in this area of engineering, all the points above just a summerization of my sense and experience. I merely know what is roll-center, also understand that spring rate affects the movement of roll center, but I cant tell where is the roll center in my AWD...XD

I agree, harder front spring, rolling is reduced and so is the traction. But, IMHO, harder front spring also has a more direct response when you entering a corner and so is the front traction. And it cause CG fliping in a larger dynamic rage. If the suspension and the chassis could not response to the rapid shift of CG, roll over is the result.

um...do you think a F-1 chassis mounted a double decker bus body and with the same CG of a real double decker has could turn fast without traction rolling when using solid block as spring in its suspension?

For the question "when you changed the springs, did you readjust the shimming (shims) to KEEP the ride height you were running with?" The answer is no unless the spring rate different is large, I see the difference neglectable.

I love this kind of fruitful discussion, but only me and you contributing is insuffisient and boring....perheps this is not the right place to discuss this kind of topic....

by the way, if you only think about a part of the track, it is useless. see whole picture better than a small part of it.
samy 發表於 2009-5-16 16:14

                               
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I wanted to point out this in the very beginning, but he wants to focus on a specific kind of turns and a specific kind of problems I try not to OT in this respect. XD

30# ganboy


You said,' harder front spring also has a more direct response when you entering a corner and so is the front traction. And it cause CG fliping in a larger dynamic rage. If the suspension and the chassis could not response to the rapid shift of CG, roll over is the result.'
You are absolutely right to have pointed this out. I had been thinking about that. A bumpy track gives an opposite answer, particularly when people put a 'disc' at the corner which 'stands' up. I have to admit that I had been assuming a flat surface. I wish to keep things 'clean' so we can focus.

30# ganboy


But when you said ,"The answer is no unless the spring rate different is large, I see the difference neglectable." I can't agree with that. I don't think the difference is negligible. A pair of softer front springs that give a lower ride height make a big difference. Though I do not always measure the ride height, I can still tell the difference. I do not usually use shims at the bottom to shim down the chassis. I usually let it droop so I can tell that more easily.

I love this kind of fruitful discussion, but only me and you contributing is insuffisient and boring....perheps this is not the right place to discuss this kind of topic....
ganboy 發表於 2009-5-16 16:42

                               
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Samy & Relo are joining. and I guess there are a lot others who read and later they will contribute too.

35# billy86che
經過多日研究兩位偉人嘅理論，以及嘥左成千銀去三聯書局買左三本字典去查你地啲咁深嘅英文，得出嘅結論係.........我揀等無人喺度嘅時候，鬼鬼鼠鼠咁改左條track，改到佢唔cup 車為止，想即刻唔cup又得.....慢慢唔cup又得.....得左

35# billy86che
經過多日研究兩位偉人嘅理論，以及嘥左成千銀去三聯書局買左三本字典去查你地啲咁深嘅英文，得出嘅結論係.........我揀等無人喺度嘅時候，鬼鬼鼠鼠咁改 ...
piano 發表於 2009-5-17 16:37

                               
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正衰鬼黎嫁!

改track是最根左性的,換乜鬼彈彈wo,不如討論乜星座配乜彈彈重好！

"改track是最根左性的"? I don't understand.

"改track是最根左性的"? I don't understand.
billy86che 發表於 2009-5-29 10:50

                               
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要洗多成千銀去買埋中文字典... 但結果都係唔明.