2005.01.12, 02:05 PM
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#61
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Registered User
Join Date: Dec 2002
Location: Southern NH
Posts: 583
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[QUOTE=InZane]
Our theory is that a slightly higher roll center makes the car less prone to have problems with “traction roll” (the center of gravity and the roll center are moved closer to each other) – this is a much bigger problem on carpet or rubber tracks (rm makes things even worse) than low traction.
QUOTE]
Please explain your theory on roll center to me. High roll center pretty much is the worst thing to have with a car that traction rolls. Lower the roll center you gain rear bite and the front pushes instead of digging in and flipping Your talking about weight thrown over the front axles the higher it is the easier it is to throw the weight.
Also explain to me how RM is inferior Look at the balance point of the cars or any pan car. Even with RM the balance point isn't as far back as it is with a 12th scale and they have 3 times wider foam tires in the rear. Spinning rear tires aren't going forward My theory is to plant all the horsepower.
You can get away with a lot with a stock motor or x speed Kinda like the Ferrari and a mini van driving a round a crowed parking lot, they both take turns about the same. Anything handles at low speed
Your car is different from the mini z but what has improved. I see about the same CG as the MR-02 balance point is further forward great for traction roll, smaller cells less run time. Looks to me like you just made something diffrent. Maybe even alittle worse than stock from my point of view.
Enjoy your Sweden World Cup I'm having the championship of the universe at my house.
Feel free to pick apart the pro-z please back it up with facts.
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2005.01.12, 03:33 PM
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#62
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Don't get mad-Get InZane
Join Date: Jan 2004
Location: Sweden
Posts: 182
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Designing chassis is a question of personal choices.
There are no simpel answers for what is wrong or right.
A forum like this can be a perfect place for exchanging idéas and experiences with others.
You don't have to get mad if not everyone share your opinion - maybe you can learn something from others instead!
All that it takes is curiosity and thirst for knowledge.
Please - Pro-Z racing, I'm not critisizing either you or your products.
One of the reasons for the rapid growth of prototype class racing in Scandinavia is a very "open" climat between drivers/developers - maybe we should try having this international as well.
The theory behind less roll moment less traction roll is described >> here >> .
Please feel free to explain in a polite way if you disagree.
I hope we can get an invitation the the championship of the universe - I'll be there
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2005.01.12, 04:25 PM
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#63
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4play
Join Date: Nov 2001
Location: Reflex Racing, everywhere
Posts: 2,602
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ruknd - as for rear end options on the Pro-Z, we will be trying an Atomic damper plate system on the Pro-Z V.6 next weekend.
Pro-Z - while I'm no moderator, I'm going to suggest that you watch your tone. You are quickly taking a technical discussion of different chassis concepts and turning it into an antagonistic debate. InZane just expressed the opinion and reasoning behind his design, and made no criticisms towards your design. I have been more than diplomatic about my experience with the Pro-Z V.6, and I would expect the same courtesy from anyone else in this discussion.
That having been said, back to roll center and it's effects on traction rolling. A lower roll center increases the effect of the cg about the chassis. It increases roll. While this is good for generating traction, it encourages more chassis roll at the same spring rate. Traction and chassis roll combined at extremes produces traction rolling or snap rolling. By raising the roll center, the cg has less leverage on the roll center and reduces total traction. By reducing traction and limiting roll, you effective counteract traction rolling. It doesn't matter if it's in the front or the rear as it's affecting the roll axis either way and taking traction away from the car. Now keep in mind that you are reducing side traction (sidebite), but maintaining forward drive traction which is based primarily on tires and weight shift. By raising the roll center, you can theoretically dial in as much or little sidebite as your chassis/tire combo can handle, while maintaining all of the forward drive associated with running fat sticky tires.
Also, I for one would love to be able to run the smaller lighter cells. AAA has way more runtime than is necessary for even 8min racing.
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2005.01.12, 04:29 PM
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#64
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Un-Retired R/C Racer
Join Date: Jan 2005
Location: NYC
Posts: 18
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Quote:
Originally Posted by ruf
ruknd - as for rear end options on the Pro-Z, we will be trying an Atomic damper plate system on the Pro-Z V.6 next weekend.
Pro-Z - while I'm no moderator, I'm going to suggest that you watch your tone. You are quickly taking a technical discussion of different chassis concepts and turning it into an antagonistic debate. InZane just expressed the opinion and reasoning behind his design, and made no criticisms towards your design. I have been more than diplomatic about my experience with the Pro-Z V.6, and I would expect the same courtesy from anyone else in this discussion.
That having been said, back to roll center and it's effects on traction rolling. A lower roll center increases the effect of the cg about the chassis. It increases roll. While this is good for generating traction, it encourages more chassis roll at the same spring rate. Traction and chassis roll combined at extremes produces traction rolling or snap rolling. By raising the roll center, the cg has less leverage on the roll center and reduces total traction. By reducing traction and limiting roll, you effective counteract traction rolling. It doesn't matter if it's in the front or the rear as it's affecting the roll axis either way and taking traction away from the car. Now keep in mind that you are reducing side traction (sidebite), but maintaining forward drive traction which is based primarily on tires and weight shift. By raising the roll center, you can theoretically dial in as much or little sidebite as your chassis/tire combo can handle, while maintaining all of the forward drive associated with running fat sticky tires.
Also, I for one would love to be able to run the smaller lighter cells. AAA has way more runtime than is necessary for even 8min racing.
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This man knows what he is speaking about.
__________________
Formerly of Alpha & Omega Racing Products. Hitec/RCD, RRP Mini-Z newB!!
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2005.01.12, 04:31 PM
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#65
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4play
Join Date: Nov 2001
Location: Reflex Racing, everywhere
Posts: 2,602
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And nelson is gh3y. And he likes to hang out around truck stops.
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2005.01.12, 08:35 PM
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#66
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Registered User
Join Date: Dec 2002
Location: Southern NH
Posts: 583
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Yes, i apologize I shouldn't be so testy.
We have discussed the world championship thing before.
Ruf - if we were talking about a 4wd 10th scale i wouldn't disagree But not so on a 2wd pan car. You are right about the difference in traction roll and snap rolling. With the decreased weight the rear is more likely to slid untill the side wall bites and snap rolls. With the short wheelbase and high horspower rear grip is already scarce.
And I believe we discussed this alittle bit with your car (brian's car ) tri poding as the soft side spring rate would lay over, not snap roll. This lets you run stiffer spring rate and cut harder into a turn. Granted this is a preference but compared side by side a car that cuts harder will carry more speed through a turn.
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2005.01.13, 12:57 PM
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#67
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Don't get mad-Get InZane
Join Date: Jan 2004
Location: Sweden
Posts: 182
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Our reason for using 2/3AA cells is not because they are smaller/lighter - in fact they are slightly heavier than AAA cells (1,5 gram).
The best cells that we have found are KAN batteries - much favoured by the electric RC flyers because of their ultra low internal resistance (much more important than capacity).
The two cell types differ only by the dimensions - 2/3AA are shorter but have a larger diameter. The characteristics are otherwise very similar as you can see on the attached chart.
We have chosen to use these cells because they give more space for the electronics on the chassiplate. Another advantage is the low price and their superior ability to "survive" large amp loads (this makes them even more economical in the long run).
>> The CBP 750 cells >> are said to be very good - romours say they are originaly Kan cells with a CBP label.
If you're planning to build a 1:27 prototype chassie we think you should strongly consider this alternative!
I'm also attaching a picture of a new Scandinavian prototype - the MGZ- MkII
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2005.01.13, 01:36 PM
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#68
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Don't get mad-Get InZane
Join Date: Jan 2004
Location: Sweden
Posts: 182
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Oval racing - European Style
I know it's off topic - but you just have to see this video by my friends from France!
>> Oval InZanity >>
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2005.01.13, 03:12 PM
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#69
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fast and out of control
Join Date: Oct 2004
Location: New York
Posts: 2,507
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InZane...I'm confused does your car take these batteries or standard aaas?
One thing that concerns me when you use a three point suspension as inzane has is that the dampening rate, friction, and movement are not equal all around...this is why I like the friction damper on a set up where the shock is essentially mounted horizontally.
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2005.01.13, 04:36 PM
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#70
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Don't get mad-Get InZane
Join Date: Jan 2004
Location: Sweden
Posts: 182
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We are using 2/3AA KAN cells.
The most important thing is to have some kind of multi directional damping of the rear end. Both disc dampers and tri shock set ups are OK.
If you use a disc damper you need an extra spring loaded damper pointing forward for dialing the in-steering (I'm sorry if my English sometimes can be a bit cryptic).
There is a problem because this damper gets a more forward position than if you use tri shocks (small car - no space).
Most of todays 1:12 pan cars have damper tubes instead of a damper disc - we haven't had any problems with unequal damping rate or movment with the Pro27.
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2005.01.17, 03:47 PM
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#71
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4play
Join Date: Nov 2001
Location: Reflex Racing, everywhere
Posts: 2,602
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Pro-Z - perhaps you are right about pan car design. I personally want my Z to handle more like a TC anyways. Just something for me to experiment with.
InZane - I stand corrected on the weight of the 2/3AA. I would like to run 2/3AAA or something to get the weight down. Eventually I want to start experimenting with thin film batteries just for fun. The thing is that the battery standard needs to be locked down eventually for competition purposes.
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2005.01.17, 04:27 PM
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#72
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Registered User
Join Date: Dec 2002
Location: Southern NH
Posts: 583
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Ruf - That will be tough with a 2wd straight axle car. Pan cars are more a point and shoot driving style Xmods feel more like a TC but the drive train is inefficient. Li- Poly cells are great nice and flat. I have been using some LI-Ion AA cells in my car they are surpassingly light and have 3.7 volts per cell the 2 li-ions AA weigh less then the 4 NiMH AAA and 7.4 volts 700 mAh to boot.
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2005.01.17, 04:41 PM
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#73
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4play
Join Date: Nov 2001
Location: Reflex Racing, everywhere
Posts: 2,602
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The new thin flim battery technology is basically an upgraded li-poly cell. They are using a new technology in forming the film electrolyte. It will blow any current flat battery out of the water when it finally becomes available. Incredible cycle life, charge and discharge rates, and energy density.
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2005.01.17, 05:31 PM
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#74
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Registered User
Join Date: Dec 2002
Location: Southern NH
Posts: 583
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I heard NEC has some new carbon Oxygen somthing based cell that will have a 2 min recharge
Definaly some killer stuff around the corner.
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2005.01.17, 07:34 PM
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#75
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MAN SHOOT
Join Date: Nov 2003
Location: bay FARRRM
Posts: 400
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INzane, is it possible for people in US to order this chassis of yours? And how much will it be when it comes out? Thanks.
__________________
FastCraft
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