120 Mph 1/10 scale electric rc car

[mcalpinerc]

Hi all!!!
I've built a 120mph 1/10 scale 4wd electric rc car
goto www.brainlubeonline.com and click on "The ALX-1 super RC car"

please email me with suggestions and comments

thanks,
Am
www.brainlubeonline.com

[SerpentKing101]

crazy name, but im liking the dual motor thing :D Guess i got beat to the punch.

oh well. Owning the worlds fastest TC3 will be good enough for me.

[Sorcerer001]

Not to be rude, but there's nothing about your car that would lead anyone to believe it'll hit 120 mph. Did I miss the video or something? The only thing you've done is make a dual motor mount. Adding an additional motor will do very little in terms of upping top end. 05 motors will not hold up to 14.4 volts, so I assume each motor will see 7.2 volts. On hot mod will spin a spur just as fast as two of the same motor. The only real advantage would be with regards to torque. You could run taller gearing. But why not save weight, run a larger diameter can that can handle higher cell counts, and mess around with gearing.
Don't forget about the tires. Any commercially available rubber tire on the market will most likely blow apart at anything above 90 mph.

[studysession]

Nice design.

[Spoon37]

interesting, and very cool.....

but IMO - make it longer. CF sheet isnt that hard to come by or work on(just dont inhale the dust, especially if using power saws!), and the centre shaft should be a peice of cake. making it longer will make it more stable, allow more room for the 24? cells u plan to run( "they will run at 14.4 volts with seperate power supplys.), and should get the power down better.

I am presuming that you have worked out the best power/weight ratio and therefore the weight of 24 cells and 2 motors will still be ok for your gearing? - dont forget gearing calcualtions need to be overkill for your intended speed as you will have transmission and grip losses all over the place.....

but sorcerer has a point on tyres - it will be the achiles heel of many entries.....

but still a cool project nontheless....

:D

[Voodooboy52]

Go to materials, then final car. Theres more to it.

[moddedsnrally]

i was thinking, if you are going to run two motors, why not have one for getting up to speed and the other have a really tall gearing so that once you get up to speed on the first motor, the second motor will take it even faster, i know it might be overkill, but why not try.

[minitdriver]

120??I don't believe it.Sorcerer is right 2 motors won't help for that top speed advantage.Those tires got to go.Where are your cels going to go???Plus you need to spend more time on your gearing then diobnium brushes or whatever.But still a nice car.
Ken

[racerrandy]

Cliff Lett ran 96 mph, with 14 cells and a 05 motor. The limiting factor in normal 05 motors is the magnets. Cliff's used a drag can with neo mags. I have two of them coming myself.

He also used store bought tires on the tc3 at 96 mph, and l30 at 111 mph.

You guys should really do a little homework before you slam the guy. I don't see how anybody can say his project won't work unless you know for a fact!

Later,Randy

[RS4ss]

racerrandy is right, store bought tires hold up under high speeds, it you have them glued right or use a hard enough compound. i just ran 92 with my twin .70 and used proline tires. but, they were balooning. so we changed to hard compound foam and changed gearing. we dont know speeds yet. but it out ran a 5.0 mustang chase car. im estimating it hit near 125, easy, but not for sure. we'll see you at the competition...

[studysession]

I ran 93MPh with my Colt10 using tires manufactures by Carson Models. I get them for free from my sponsor. So I am not going to go buy others if I get the for free. I think 93MPh was a good run myself.

http://studysession.com

[StevePond]

Wow, looks like a WHOLE lot of trollin' happening in this thread. :D

[Spoon37]

hmmm hard compound tyres work best huh? cool - so that means there is going to be a roaring trade in stock Tamiya Tyres?! lol :p

;)

[TrickSpeed]

Cliff Lett ran 96 mph, with 14 cells and a 05 motor. The limiting factor in normal 05 motors is the magnets. Cliff's used a drag can with neo mags. I have two of them coming myself.


Where did you get the cans?

[racerrandy]

Here is the link. If you give a call tell him I sent you.

http://www.neomags.com/

Later,Randy

[WheelNut]

Ok, after looking at your design (ALX2), it certainly seems novel. But why would you use this PDT steering system, I really cannot see any advantage. Yes you reduce the unsprung weight, only slighty though, the weight of 2 Al ball studs, 4 plastic ball cups, 2 Ti turnbuckles is almost nothing, and a small amount of added plastic on the hub, is really hardly anything. Mabye over 15g. And this system looks to use many, many more moving parts, plus it would be alot heavier. Also why bother with the rear steering? It looks like extra bulk, and by all accouts I've ever heard 4ws is not an andvantage. A very small amount I assume will be benificial, though it could induce serious oversteer farily easily. The Honda prelude used to use a 4ws system.

The suspension seems to be basically a Pan car setup with rigid lower arms and in this case rigid upper arms. But I dont see in the drawing how those arms from the top of the hub to the rocker for the suspension would compress the shocks at all? The hub looks like it just moves vertically and the rod would need some horizontal motion to compress the shocks.

Mabye you could give us some more detailed, higher res pictures, using different colours that are easier to see, or just change the lighting.

Looks like you could have a fast car on your hands, though I think the complexity could hurt it. Also have you looked into Li-poly batteries, or are you going to use old school nickle based cells?

Are you actually going to make this car?

[Hz-R]

Some intresting ideas there, and cool to put them out there!

I have also found some points that don't quite match up:
- I noticed the same thing as wheelnut, how are the shocks actuated? They just seem to be connected to the top of the kingpin.
- You mention your steering system is ackerman reducing. Ackerman is normally a good thing, cause it makes your tires follow the right radius in the corners. How is reducing this an advantage?
- 'The chassis is very flexible' , this is not a good thing, cause the suspension won't be able to do it's work properly. Then again, maybe you won't need them shocks!
- Your motor mount adds rear traction. Can you explain this a bit more, would be intresting!

I'm also not so sure it will get up to 120MPH, but with some improvements, who knows! Build it and prove us wrong!

I don't agree with the idea that 2 motors won't give you a higher top speed as some mentioned. You have more power (which you need) and can therefore gear the motors higher because they have less car to pull while accelerating. It won't double the speed, but if build right, the top speed should be higher!

keep up the good work!

Robbert

[ajg]

How much higher top speed will neo magnets give you? Also, my store bought foam tires can go over 100mph and not come apart.

[Hz-R]

Maybe Schumacher red compound tires are the way to go. Used them on my buggy for races on asphalt and it took a whole summer to wear them out.
How's that for hard compound!? :eek:

[racerrandy]

The main purpose of the neo mags is the abillity to run more voltage. Normal ferrite mags will work for 6 to 7 cells but more cells will over saturate the mags and kill them.

Later,Randy

[ElectricThunder]

Don't neos also give more torque?

[ajg]

Would I be ok running 8 cells on my Epic 10 turn motor? Or do I need noe mags?

[p.n.e]

The main purpose of the neo mags is the abillity to run more voltage. Normal ferrite mags will work for 6 to 7 cells but more cells will over saturate the mags and kill them.

Later,Randy
i wasnt aware of this, i ran 10 cells thru a 9 turn motor with ferrite magnets and didnt notice any damage

[WheelNut]

Yes you can run over 7 cells on ferrite magnets, its just that once you get over 7 cells having more and more cells gets less and less effective. Probably exponentially. Lets say you had two motors, one with ferrite mags and one with neodyum (sp?), both on six cells, then went up to 12 cells the improvement you will see in the neo motor will be much greater than the improvement in the ferrite motor.

[Andrewg]

The limit on 05 motors are not the magnets - the main limit is the electro-mechanical commutation.

The Neo magnets give better torque and improved efficiency at high current levels -above 55-60 amps - they also slow the motors rpms which allows higher cell numbers - voltage being cool power - amps creating heating.

On low cell counts power output is only marginally different between ferrite and Neo but neo wins because of much higher torque, better efficiency and less power drop off between max power and max efficiency.

In boats which use high continuous current setups - even the best motors (plettenburg) seem to suffer from increasing brush resistance due to heating in straightline events - dry ice in a cooling vent directed at the brushes might help - or a servo releasing a cooling gas - anything that can sustain cooling directly to the brush-comm interface

IME - 12 turns seem too few - altho you will have extra Ir in the motor 14s ón 12 cells will let you use more voltage - which will give you better efficiency and more power.

My experience has been while fat comms have lower resistance and rpms. The tapered shank arms are not as effective as the small comm standup brush setups in making power when you are pushing the setup as hard as the cells can give. It may because the brushes/comms can only stand so much heat.

Also the Nicad 2400 are no where near as good as GP 3300's if cell numbers are restricted. The GPs have a significant voltage and current advantage - in 12 cell setups it is like an extra cell over 2400's - on the other hand an extra 12X2400 plus a 13th cell is like 12 GP300's and weighs about the same.

[asw7576]

no hard feeling, 120 mph its a bull ......