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Old 04-12-2009, 08:48 AM   #1
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Default rc speed record?

After finishing school and defering my uni degree, I've had alot of time on my hands. I need something to do Lately my interest in the hobby has regrown and I've been pondering the idea of attempting an 18th speed record. It is early days yet and I'm not sure if I will follow through with the idea. I don't know what the speed records are for 18th scale or the best way to achieve them but I'd like to hear peoples thoughts on my ideas.

My image is a micro rs4 running on a 6s2p lipo. The battery layout will have to be whacky because the rear needs to pivot for the suspension to work and I need to make room for the belt also. I only have 2 of the size battery i want to use (3S) but for the 6S2P it will require 4 so I will try to illustrate as well as I can with photos. Just add both battery placements together to make 4 batteries. For the rear suspension pod to pivot, the backmost battery will be raised slightly and mounted to the upper deck. Setup like this the batteries will output 40C and 3000mah at 22.2v. These are only cheap batts though so higher quality ones like thunder power etc. would most likely have a higher discharge rate.

because of the battery placements, I would have to put the motor behind the back wheels and the servo infront of the front wheels. This would only need a custom motor plate and the front axle hubs switched which are minor mods. But I am worried about the motor being further past the rear suspensions point of pivot, meaning virtually a larger unsprung weight upon the chassis and larger "shudders" to the motor. The motor wouldnt be the 380 shown in the photo for illustration but most likely a 430 because i believe they are the largest that can fit between the rear wheels.

I know the micro rs4 is more or less an expired chassis and the M18 is far more recent and advanced, however I think the MRS4 driveline and weight distribution is more suitable for high speeds. I do know that the MRS4 does have some weak points however, like the front end drivetrain which breaks under any strain. What I am most worried about is weight, weight distribution, aerodynamics and tires though.

It is still only ideas in my head, though. I need to save for uni more than anything and this won't help that haha. But I still wouldn't mind trying this.

I'd like to hear some hobbyist thoughts and ideas on this. Cheers
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Old 04-12-2009, 04:53 PM   #2
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hey,nice to see more people into speed.

firstly, (asuming your from america) go to isc.com as they are the speed guys over there (im from uk)

for a speed run car, your pretty on the ball, shame there isnt a ball, anyway...

i think the 6s2p, is ambitiouse, and for it to be official it has to stick to production parts. i sugest maybe a smaller battery.

your plane is...ambitiouse, stick to smaller batterys, maybe a flightpower EON 33 as they have high discharge rates. for wheels, go with foams as they wont balloon. aerodynamics, a normal body is fine, you could cover up (i.e not cut out) the rear wheel arches and add two little spoilers to the front for extra downforce.

packed with a decent brushless and good gearing, that will make a good starting point.

also another thing to look out for is radio range, it needs to be big. the current record i think is in its 80's (mph) so it will be tough, but good luck!!

if you have any other questions pm me, and ill point you in the right direction...

thanks
chris
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Old 04-12-2009, 08:33 PM   #3
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Quote:
Originally Posted by kwik-kid View Post
hey,nice to see more people into speed.

firstly, (asuming your from america) go to isc.com as they are the speed guys over there (im from uk)

for a speed run car, your pretty on the ball, shame there isnt a ball, anyway...

i think the 6s2p, is ambitiouse, and for it to be official it has to stick to production parts. i sugest maybe a smaller battery.

your plane is...ambitiouse, stick to smaller batterys, maybe a flightpower EON 33 as they have high discharge rates. for wheels, go with foams as they wont balloon. aerodynamics, a normal body is fine, you could cover up (i.e not cut out) the rear wheel arches and add two little spoilers to the front for extra downforce.

packed with a decent brushless and good gearing, that will make a good starting point.

also another thing to look out for is radio range, it needs to be big. the current record i think is in its 80's (mph) so it will be tough, but good luck!!

if you have any other questions pm me, and ill point you in the right direction...

thanks
chris
Thanks for your help. Actually, I'm from Australia mate I had a look at the EON 33. It does have a very high discharge rate for its size, but they all seem to have small capacitys. I think the 6S2P idea is ambitious too. It will add an enormous amount of weight to the car and also give it a higher COG, but it would be good to run a larger brushless. For the body, I was thinking of sealing it to the chassis (as much as possible) to make a much more aero underside and maybe also a custom body for increased aerodynamics. So for the record I need to stick to production parts you say? Even if the end result still has a perfect 1:18 wheel-base?
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Old 04-13-2009, 02:20 AM   #4
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You really don't need battery's like this. A 1500mAh 11.1V pack will be more than enough (With a good brushless motor/esc)
There was/is a 540 motor conversation for the Micro RS4. Even with a 6cell Nimh pack and an old 17t motor, there was more power than I could handle. The short wheelbase makes it hard, to go fast (even straight away)
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Old 04-13-2009, 03:31 AM   #5
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You really don't need battery's like this. A 1500mAh 11.1V pack will be more than enough (With a good brushless motor/esc)
There was/is a 540 motor conversation for the Micro RS4. Even with a 6cell Nimh pack and an old 17t motor, there was more power than I could handle. The short wheelbase makes it hard, to go fast (even straight away)
yes the 540 conversion was hard to handle fast, but I believe that would be mainly due to it requiring a wider wheel base and a really heavy rear end. The 540s needed the rear tires to be significantly far apart to fit the motor, I think by memory even further apart than the widest standard setting. A more narrow wheel-base, like the one I'd plan on using would be more stable at higher speeds. ATM I have been running 3S lipo on my mamba 25 comp x. I'd estimate its speeds at about 80-90km/h at which I have absolutely no problem controlling the car. But the record is roughly twice as fast so I'm not so sure how the car would handle at that speed.

I know that a 6S2P lipo seems extravagant, but I really want the 2P so that I can boost out the amps needed to support a powerful brushless. I might just try 3S2P and see how that is with a large brushless, or get 4 2S packs and use 4S2P. On that note, my layout has now just changed dramatically

What I now need is to find a place to obtain a pinion to fit a larger shaft with MRS4 pitch teeth... Anyone?
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Old 04-13-2009, 01:47 PM   #6
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I seriously don't think you need the 2p. Maybe a cell that's twice as big, but 2p will make it harder to mount.
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Old 07-20-2010, 04:44 PM   #7
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Smile my speed record

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Old 07-20-2010, 07:01 PM   #8
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for any and all info on how to accomplish ur goals with speed records...

"Seek out Mr. Nic Case."

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Old 07-28-2010, 03:11 PM   #9
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"Seek out Mr. Nic Case."

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Old 07-28-2010, 07:07 PM   #10
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The current ISC 'mini' class record is 87.98 mph by TJ Kendall, so that would be the number to shoot for.
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Old 07-29-2010, 12:07 PM   #11
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I got my Tamiya F201 up to 110 MPH for about 2 miles on the beltway.... I held it out the window of my Mustang.....

Does that count?
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