controller advice for fastest car event
 

Hi there.

Im entering into the fastest r/c car challenge in march and ive got a specially modified rustler to equip with brushless.... i wont go into much detail but i need the help/advice with the setup...

Ive got a 7xl handy and a maxamps 6s 4000mah lipo....

Im torn between the quark 125b and the MGM 9032 car controller.

Yes the quark 125b is alot cheaper. but from what ive seen by searching this forum i can bring up 5-6 burned out 125b controller threads.. i dont want it smoking on me! :-(

Is it worth spending nearly £200 instead of £150 on a better controller...

Cheers
Matt.

I haven't tried it personally, but there was talk of problems with 6S on the 125B, even though it's supposed to handle it (not sure if they've made any changes to fix this). Other than that, its a great controller and I've had no problems.

I'd want a greater cushion on the amps from the MGM90 - 7XL will pull a lot....

This is rated to 8s which would be fine - is the same price and goes to 160amps...

http://www.rc-monster.com/proddetail...MM160243sHCS01

I would say that your choice of motor is slightly unmatched to your spend on ESC. Also don't know what that motor will do at 60k.

I had a 9XL magnet shatter on 4s...

Q125 - no one seems to run it on 6s for long...

yes but thats out of stock mate.....

i need to order so need somthing in stock.... ether on rcmonster or elsewhere...

7xls r sooo cheap tho soo not worried bout that...

Matt.

I would say that a l can feigao motor around 3000kv will hold together better than the 7xl, and spin faster. You will need some ceramic bearings in the motor too. As for the esc, a qaurk may work, but you will need to add extra caps to it, this is a must.

sod that...

how long will MGM's be?
ive already got the motor so...

Matt.

What an eloquent way of saying something!

ok ill rephrase.

sod trying to do that, ill nak it up lol..

Matt.

Dogs Bollucks!

7XL works fine on 6s with the MGM 16024.

Well whatever you do don't by from Mattymaxx. He has messed up transactions from unlimitedengineering.com forums and has a paypal dispute.

You should not have messed up geaorge16, an active military member in the Navy like you did.

Not to worry Matty, the word is being spread to every forum you are a member of,
Mattymaxx does not delive what he has been paid for of a few occasions, and makes very make excuses and takes his time to respond to any info requested. If anyone is reading this do not do business with him as he is unreliable.:gasp::intello:

the cheek of you pal. im not the sort of person to discuss my transactions online and publicly give out every detail. I have indeed sorted this out with paypal and have sent george numerous emails about it so dont you dare start dishing out rubbish which is NOTHING to do with you.

fool.

Matt.

So I say again, DOGS BOLLOCKS!!!

sorry mate i cudnt understand a word of that, u talk shit...
its note to do with u ether u freak.

im sick of people getting involed and jumping to conclusions when they have no right.... and they dont no the full story

Matt

what a fun day to be on the forums. remember thr hickoryhead scandal? the cheek of some people!:lol:

nitronaught; you mind not getting involved with this on this forum? your first two posts are not exactly contributing anything here.

if you disagree, you can contact me by PM.

Licpimp; if i where you i would stay out of this.. We all know you carry your own opinion, that's all known by now.

If anyone has got anything to say about this, feel free to PM me.

It's simple. And george16 explained everything to me in quite some detail.

BTW you mess with a serviceman on active duty, and I know about it. I'll say something.

Silly boy, tricks are for kids.

I'm not dishing out any rubbish, truth hurts! I've been around a long time. This is something I normally don't do.

You just need to get a pair, grow up. Stand up and be honest.

I love the story of how you shipped the item and it was returned cause the package was damaged. That's a good one.

How long has he waited? Over 1 month since payment? Humm. You could have delivered personally in that time.

I don't blame you not wanting to talk about it publicly. Just grow up boy, and be a stand up guy. Especially when dealing with U.S. Navy active servicemen. You mess with one of them, you mess with all of them.

I was one of them. SO your stuck.

And yeah, if you pull a bad transaction and mess someone over you ushould expect some flack. Your gettin it.:diablo:

I think preventing people from getting ripped off is contributing. What, you would not want to know that someone has jerked someone around on a private sale? loll
If that's the case feel free to buy expensive parts money up front from someone who has not kept their end of the deal.

Sorry I feel it's quite contributory. It did what I wanted to do anyways. brought Mattymaxx out..:intello:

With all respect;

I HATE it when unjustice is done,

But this is post number three of you on this forum regarding this matter, and not a single other post has been made. and if you question me I'll rather discuss this with you by PM.

For the sake of RC-Monster I ask you to back out of it, unless you are planning on contributing something to the world of brushless RC. Mattymaxx has been a member here for a longer period of time and i hope this entire situation comes to an end soon, i am sure that he can solve it. if there is anyting I can do in this matter just let me know.

@nitronaught; If you fire off another post regarding this subject, i want you to contact me first and tell me the entire story.

PM sent. http://www.rc-monster.com/forum/images/icons/icon6.gif

Oh, the drama, the drama.... never a dull moment 'round here.

bottom line is, he has my money and my parts now....

So lets get this straight he has his money back, and he has the supermaxx parts. So im such a scammer arent I :-/


Matthew.

Dang, Never a dull moment!! :lol:

yeh your helping mate.....

OK, I have a novel idea: How about we all go back to the original topic now?

We don't want to have Serum get back here to find the conversation has continued in his absence. You wouldn't like him when he's angry. Ever see an angry grown man in an anteater costume? 'Nuff said...

sounds good to me. im sick of the lies and people jumping to conclusions anyway....

Matthew.

What are you doing for the aerodynamics of the car? This seems to be the biggest problem in this event from what I have read. Traction and aero seem to be the biggest problems?

Yes, traction and aerodynamics are a problem.

For a 10th scale car, you can achieve 90mph with 2 hp and good tires (caps or foamies) and some aero work. 100 requires 3hp at least, VERY good tires (BSR caps work best), and VERY good aerodynamics.

Matt

well im basically just going ot giv it the power then at least i can just play with the thing to make it go faster splitters, ride hiehgt, etc....

power wont be an issue im sure!

Matt

You would be surprised! I thought the same thing. When it comes to high speed, power is ALWAYS an issue.

Matt (the other Matt) :mdr:

Anyone know how to calculate drag coefficient for a given speed? I'm sure that's a major issue at those speeds. I'd look it up, but I'm lazy. :oops:

CD (coefficient of drag) is a hugely complex thing to calculate. There is alot more than merely frontal area to consider. There are factors like screen friction (air dragging on the sides of the car), the cowanda affect (spelling?). That is the tendency of the air to hug the body as it rounds a corner rather than skipping off the body creating turbulence and, therefore, drag.

When I designed my CF body, I stood it up (nose in the air) and ran water over the body (steady stream of water running over the body) looking for turbulence in the water and the tendency of the water to hug the body rather than skip off at various curved areas. Water is 800 time more dense than air, yet the same fluid dynamics apply with air as water. So, you can get a good idea of how the air will behave with your body by watching water run over it.

Am I making any sence?

Matt

The Quark will handle 7s A123 no problem, not quite 6s lipo under acceleration.... but for top speed, it will hold near 23volts, which is all that matters for you, right?

Although, you might want to solder two extra low-esr caps onto the input power leads. I did.

Water and air are both fluids yes, but water cannot compress like air... the only way to test a shape for air turbulence is, well air.

How about a Pheonix HV 125amp? Isn't that what Nic Case was using for his serpent?

btw, where will the speed challenge take place? If its in CA again, I may attend. I don't have a crazy fast car since all of my rides are purpose built for tracks and bashing, but I'd love to go and watch. I may even enter one of my slow rides just to say I took part in it... lol.

Seriously though, I was thinking about entering my zip zap in the event. I think I can get that thing to about 10mph... plenty fast enough to take home a trophy... don't you think?

I kinda figured it would be extremely difficult to calculate, but was hoping for some miracle constant. :lol:

Like ZPB said, using water is not exact, but it sure is a lot better than nothing. At least it gets you in the ballpark. ZPB: you have a wind-tunnel I can borrow? :wink:

You have a link to that? The only thing I can find in the Phoenix line is the HV-110...

There's always the Hydra ESCs; a 120, 180 or even a 240 would be plenty enough! Or, you could wait for the MMM; that too should be plenty, and will of course have brakes you can use.

The think about the Hydras is the price (compared to the Phoenix) and need to replace the water-cooling tubes with a finned heatsink...

D'oh...good point! I didnt think of that lol... :)

One thing I know though, is if you use the general shape of fish... if you have some gold fish, these have a nice curve ratio that is appealing to a car body.

I have heard Mercedes made a van that has 80mpg and doesn't even look aerodynamic really, they used a 'box fish' design.

Another thing I know is to keep the front profile shorter and more rain drop looking, and the tailing end more prolonged (fish like).


I agree, someone else said a while back that frontal area has little to do with aero's.... it's all to do with the profile. Anyways, I better stop, I am yabbering again. ;)