Re: World's Fastest R/C Car, anyone?
 

My prediction for the flat out, fastest car at the track will be a factory sponsored 'car'.

It'll probably be a 2 foot long dragster looking deal. Power will be from 1-2 high voltage brushless motors, possibly hand made or modified specifically for this car. Battery packs will be made up of sub-c cells or smaller, but not Lithium chemistry. Nickle will carry the day. The tricks will be in reducing rolling friction and weight as far as possible, and maximizing gearing. The winner will have two gears. A relatively low accelerating gear that could top out around 60-80 and a taller gear, 1:1 or higher to push over 115 mph.

High speed stability should be interesting. The crashes will be pretty spectacular. I don't expect the winner to waste much weight on a brake. How to stop it?

The winning independent car will probably look a lot like the factory winner, only slower.

-Andy A.

Re: World's Fastest R/C Car, anyone?
 

one thing i thought was cool was a college built a all electric car that tops off at 300 mph! :ahh: i saw a film it was absolutely amazing!

Re: World's Fastest R/C Car, anyone?
 

I'm just wondering, why not Lithium Polymers or Lithium Ion battery packs? Lithium is the same weight or less than NiMH or NiCD for almost twice the ampheres. It's lighter so higher top speed...or is it just because of the safety involved with Lithium?
I have a friend that runs a micro with Lithium and he always has to be careful with it. I think it's because he's scared of them catching on fire or maybe blowing up.:ahh:

Re: World's Fastest R/C Car, anyone?
 

Ever wonder why lithium catches on fire so often?

Lithium based batteries do have great energy density. The problem with using them on an R/C car like this is that they are very limited in how much current they can deliver over a short time.

NiMH don't have those same restrictions. Current draws can get pretty high with out starting a fire. This is good when your using low turn motors with high speed gearing.

-Andy A.

Re: World's Fastest R/C Car, anyone?
 

yeah does anyone know what the Milliamp per minute output for lithium batteries compared to similar batteries of different composition.

Re: World's Fastest R/C Car, anyone?
 

If they were of different composition then they wouldn't be similar right. :D But maybe you mean similar voltage and capacity.

Re: World's Fastest R/C Car, anyone?
 

Yes i do, but thank you for pointing out my lack of ability at articulating my thoughts clearly at 2 in the mourning. :D

Re: World's Fastest R/C Car, anyone?
 

I don't mean to find flaws, I just want to make sure I understand. :)

So anyway about the lithiums, the only thing I really know about them is that they are much more expensive and are used in long period low current applications like cell phones.

Re: World's Fastest R/C Car, anyone?
 

im almost positive i read an article about a company making a lithium power hand saw (im bad with tool names. its the one that is used for wood cutting. it has a flat area that the blade extends from, and the blade is cicular. looks like a jigsaw.)

Re: World's Fastest R/C Car, anyone?
 

A circular saw? Most portable power tools use NiCad batteries.

Re: World's Fastest R/C Car, anyone?
 

Well...
A 7.4V 4950 mAh LiPoly packs can be the same size as a 7.4V 3300 mAh NiMH pack, maybe a 3800 mAh because they're the same size too, but the LiPo pack will be a few grams lighter.


I know that the chance of catching fire because of the large amount of current going through the system. They have been rated at around 50 Amps discharge, while most NiMH packs are rated at 20-30 Amps discharge. But really, the LiPo packs are used just to save weight and for longer run times because a motor usually sucks just 25-30 Amps and so a 4950 mAh Lipo will last probably 1.303 times longer than a 3800 NiMH. A NiMH pack would probably last ~15-20 minutes, while a LiPo would last 20-26 minutes. Once I really think about it...A LiPo wouldn't actually mean much in this kind of competition as it's not going to be endurance. It's more or less just a sprint race to see the top speed, but a LiPo of lesser ampheres could be used just for weight.


And Mechanicalbrain, are you talking about a table saw?

Re: World's Fastest R/C Car, anyone?
 

hehe. yeah a cirular saw and im 94.2376% (to the dot) sure it was lithium and had a super long battery life which is why it was in a article in the magazine. it had to do with new lithium battery technology. ^ thanks thats exactly what i was wondering!

Re: World's Fastest R/C Car, anyone?
 

Here is the best battery info I have ever read on Lipo Batteries. I fly a micro helicopter and this is the best battery supplier. The Doc is long, but very good reading especially for our group.

http://www.fmadirect.com/support_docs/item_1115.pdf

I hear FIRST was going to us Lipo's next year in robotics. I guess the are now wanting to compete with robot wars and have fire and smoke. JK

One other thing Lithium is that stuff your science teach used to keep locked up because is self ignites in the presence of Oxygen. Ours cut a small piece off and made it ignite, then a girl freaked out and they ended up evacuating the whole school. It was a little bigger piece then normal. He got in big trouble for that one.

Re: World's Fastest R/C Car, anyone?
 

Oh yeah, I forgot about that. We actually did something similar in Chemistry...okay so we watched in on TV, but he dropped a small piece of Lithium in a petri dish of water and when it had being quite an exothermic reaction. All of the elements from Group 1A will react the same way, Sodium, Potassium, Rubidium, Cesium, and maybe Francium...I'm not sure about the last one though, does anyone know if it is or not?

So is its reactiveness the reason why they are a safety hazard if one of the packs were to get damaged and the Lithium was exposed to the air?

Re: World's Fastest R/C Car, anyone?
 

I wanted to post these two things for general amusement and i thought this would be a good thread although neither is directly related.
One: the worlds fastest car clocked at over 300 mph.
http://www.buckeyebullet.com/

Two: found this and thought it was just plain cool. Its a turbine jet powered gokart.
http://www.big-boys.com/articles/jetcart.html