rusty land speed record

[klown]

ok so I'm wanting to set a land speed record with a rusty... i have a black chassis with all metal gear tranny and a vxl setup, with a small 3s on its way here... from what i am able to find out from traxxas and forum boards across the net, 65 - 70 mph is attainable from this tiny truck. i used this, http://scriptasylum.com/rc_speed/_top_speed.html to give me a good idea of the current gearing setup i have. which is a 32tooth pinion and a 72 tooth spur gear, with a traxxas vxl setup and a 3s lipo... its telling me around 65-66 mph.

what concerns me is motor and esc heat from the gearing. can some guru's take a look at my figures and tell me real world what i am gonna cook... besides the rusty, i know that its gonna sprout wings and nvr return. lol

 

[alpinehyperlite]

From personal experience, it will catch fire.

 

[klown]

it will catch fire.

interesting results. any idea what would cause the fire result?

 

[flm_savage]

define "small lipo"

my guess is that with it so severely undergeared, running a low kv motor and with IMO low voltage, when you hit the throttle you will simply max out the battery and the result will either be a thermal shutdown on the esc or a smoldering battery.

 

[alpinehyperlite]

it will catch fire.

interesting results. any idea what would cause the fire result?

too much strain on the motor = heat = fire

 

[klown]

i got the gearing idea from the book that came with the velinenien system, it did say not to use nimh, the system requires a battery that has a continuous rating of at least 70A.
the gearing combo i have is slightly off compared to the book, it is showing a speed of 70+ by using a 31 pinion and a 76 spur... i have a 32 pinion and a 72 spur... on paper that should peel the paint off the body when its wide open... as long as it dont catch fire first apparantly.

if this edevour is gonna end up with a pile of smoldering plastic and a raging lipo fire, how is it that i have seen vids on you tube of rustys and revos doing right close to 100? and how are they achieving that kind of speed and it not have catestrophic results?

 

[SMaxxin]

Please get this on video!

 

[abadk9420]

For what you are trying to do i would find a 3 cell lipo with a high C rating, like 40C, also i would roll into the throttle and gradually bring it up to top speed to reduce the load on everything, I would also only keep it at WOT long enough to measure your top speed. This should reduce the chance of a fire or thermal overload, but there is always still a chance you could burn things up, good luck and definitely get it on video.

 

[alpinehyperlite]

For least risk of failure by flame, keep it on the road.

 

[flm_savage]

Links to the 100mph revo please

 

[alpinehyperlite]

I had my tmaxx and scalers going 100, in my trunk.

 

[syphon68]

I had my Rusty geared 31/83 on 3s for speed runs and even though I didn't get GPS on it I can say that is the fastest I have gone with an RC. As far as heat I just kept my speed runs to a minimum and the motor never went above 135 deg. I say go for it but watch your temps and know that you are putting your equipment in danger

 

[flm_savage]

how are they achieving that kind of speed and it not have catestrophic results?

much higher voltage (ideally 6S) and electronics that are of higher quality. (medusa and neu motors along with mamba monster or other high/current high voltage esc's )

 

[alien13]

Make a cold air duct. Get some lightweight plastic tubing, warm it up and form it as needed. The front should sit low, the rear should blow right at the motor. Now the faster you go, the more cool air you blow at the motor.

Don't run on fresh asphalt in the sun.

 

[klown]

here is a good link for really fast rc's... sorry, i misquoted the revo... http://rc-isc.com/index.html...

the air intake idea sounds good and i may do that with a junker body and see how well that works.

with the kind of speeds i am wanting to achieve, off road is out of the question.

rolling into the throttle untill the rc is up to speed def sounds like it would decrease alot of strain on the motor/esc combo.

the one thing that really worries me is a crash at speed would be disasterous to both the truck and my ego... lol, i can't wait... and i do plan on some video when its ready for daylight.

 

[flm_savage]

IMO if you only want speed its going to take alot more than just electronics. i would run ceramic bearings and your wheels need to be balanced precisely. All of your suspension/steering geometry needs to be dead on. One twitch and its all over at that speed.

 

[klown]

alright, i got my lipo today... gotta put the vxl in the rusty and charge and balance the battery... its smaller than i would like, but this is my first lipo so i am gonna start small first. after reviewing everyones thoughts on the gearing i am gonna start out with a slower gear ratio and ramp up from there. i def do not wanna cook anything this early in the game. after everything is put together and charged i will def post up some pics and hopefully a video. thanks for all the insight and info. this is one awesome place full of helpfull people.

 

[flm_savage]

What battery are you running?

 

[klown]

at this point it is a turnigy 3s 1600 mah. after i feel comfortable with the lipo and charging i want to move up to a much larger mah rating for longer run times.


*****update*****

so i put my velineon system in the rusty, charged and balanced the lipo. i am running a 14 tooth pinion with a 81t spur(i think) and a couple starts and stops on the living room floor later leads me to believe i need more speed and less torque. the front end wants to come up with almost no throttle. i may tear my tranny down and take out the locked diff so both back wheels wont dig, that may help with the tremondous low end torque. i didnt have time to take it over to the grocery store parking lot, literally less than a minutes walk from the house. the wife wanted to go swimming, and i would much rather see her in a bathing suit than play with cars!! lol. gonna do some more testing today and maybe a little gear work. there will def be a video in the werks soon!!!

 

[flm_savage]

What's the c rating on that lipo? You are probably past its limits