Can't break 60kmph on snow, need ideas
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So under idea conditions, 20'F with 2" of fresh snow on a hard packed road, I could not break 60kmph, despite my gearing and motor setup. OK, visibility wasn't ideal with the storm and all, but road conditions where.
Here are the specs: Rustler VXL Stock Traxxas ribbed 2.8 on the front Proline Sand Paws 2.8 on the rear Motor is a Leopard 3650 2930kv 4 pole ESC is a Leopard 60A Battery is a 2s 5000mah 20C Tonight Pinion/spur is 26/76 Final gearing is 7.97 Total power at the wheels should be 444W (0.6hp) Theoretical top speed with not tire ballooning should be 67.6kmph (42.7mph) Top speed hit is 56.6kmph (82.3% of theoretical top speed without ballooning included). It sounds like I'm close, but these tires balloon huge (close to 2"). I know I'm running into cold battery issues and did notice it hesitate if I'm trying to back up with the wheels turned. Thoughts? |
Forgot to mention, ESC and motor where cool. Lots of snow dust keeping the motor cool.
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Going to use a bit of left over thermal reflective fabric from my winter hammock project to keep the battery warm. The stuff has the thermal rating of R6. One piece under the battery and one on top. Sides are too tight to fit the fabric into a bag arrangement.
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Dare say that's as fast as its going to get on snow.
on concrete u will get closer to the theoretical top speed...but u probably will never hit it.... don't worry about ballooning to much... I suspect the voltage drop cancels that out. id recommend re-thinking the setup My LCG slash set up for a carpet off road track goes faster... its running 23/87, 35a esc, small 380 3900kv 2poll motor. on a 2s lipo with 2.2/3 jc subcultures... for speed... u have a 540 low kv 4 poll motor.... it wouldent even be braking a sweet on that gearing and voltage.... Id recommend gearing up and/or going to 3s |
Hey just another thought that might help u get closer to the top speed.... Ski's
Like this http://i140.photobucket.com/albums/r...ustlerSki3.jpg |
I've considered the skis but would like to do the wheels of I can. The car looks soo much sweeter blasting by with the wheels in the front barely touching the ground.
For gearing, does traxxas or anyone make a spur that is smaller then 76 in 48p? |
Not that I know of....
But with the 76 spur u can go up to a 34t pinion possibly more... I did it with my old rustler but I can't remember that spur it was... All I had to do for a 35t pinion was elongate/lengthen the adjustable bottom screw hole for the motor screws. here.... one way to look at a cool ESC and motor is... they are cool from great cooling and a low load on the motor (low gearing) if we increase the gearing, it will increase the load and current draw. does that make the motor more powerful?....... Big YES....why? power is volts times amps. So if u increase the amps and the voltage remains the same. It increases the motors power so the idea is to gear the motor and ESC so they don't overheat but are hot-ish. when u start getting it really hot and overheating. Sure it's producing more power but u start running into efficacy and durability issues Been a 4 poll motor its straight away more efficient and will run cooler. So in theory u should be able to gear it a lot higher than a 2 poll motor. But keep in mind..... One other thing that effects the motors power.... Traction. If its excessive loosing traction the current draw will drop right off and so will the available power |
Or u could just fit a 3s lipo on the current gearing.... Then go from there?
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3s has been ordered and should fit.
The traction was good with the 2" of snow. Will look at the bigger pinion |
Well.... Lake run was a fail. We got 6" of snow at my place and probably a foot or more at my parent's place. Way too much powder snow on the lake. I got the car moving, but couldn't break more then 10mph on it. Ended up bashing in the driveway/field with my brother's kids and mine. Turned out to be a good time when we figured out where to hit the snow bank to jump one of the wood piles. A good time all around. The battery "blanket" I pictured above worked reasonably well. It probably worked more to keep the snow off the battery then anything.
I think I got my dad hooked on land based RCs. Something about the front wheels skimming across the top of the snow with a roster tail of snow behind just has that cool factor to it. |
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