Alexv2024

iTrader: (2)

For what motor? For what track? For what outside temp?

The rocket v4/v5 motors I think like less timing than the Fantom and Reedy motors I run. Or the R1 v21s I ran before. But Im not sure, and it totally depends on what motor you're talking about.

The Reedy S+ 17.5 has a rpm and torque version and they react very differently to timing and gearing and thats the same brand motor.

rcgod

iTrader: (33)

The 5-6a range I gave was just a starting point. There are too many variables to say that’s a hard number. I had my xfactor 13.5 at 6a which was about 49 degrees on the end bell. It was fast and didn’t run hot. I dropped it to 5a last week which was about 47 on the end bell and went up 2 teeth on the pinion and it’s a whole new beast. More punch and more top end. You have to experiment with timing and gearing to find the sweet spot for any motor/car/track conditions. If I would have left the timing where it was from the factory it would have probably run hot and not performed like I wanted.

Bry195

Thanks Marcos.

There is a guy on here who started with some of my first comments maybe over a year ago (and took it further) about creating power curves at different timings by just using onboard data logging. It looks like it worked and it was allot of work. Maybe Ray57 has some advice and has worked out some shortcuts. His power curves are indistinguishable from torque/power curves. It would be great for an ESC mfg to combine there data logging with this type of IP.

the shape of the curves are identical when you compare a single timing value with motor only, on chassis, and on chassis on track. the end points of the curve just expand or contract from a mech load.

Ray deserves applause for his diligence. I dont have the patience to run through as many tests as he did.

I think for the average person who just wants to race... the stop watch is really good. start with a rough setting like maybe 5 or 6 amps. adjust the gearing to the clock. as the average motor rpm increases or decreases follow suit with the timing. when the clock no longer shows allot of impreovement play with the last degree or two to cool the motor down.

timing does 1 of 2 things. if you hit it right on the nose for the rpm you are running you get as much peak power as the motor can give. the second use is to remove peak and widen the curve. this may get ore power under the curve for some motors which makes the car more forgiving. if you go to far you lose the peak and the bottom end to get a really wide curve that spends too much time heating itself up.

gigaplex

iTrader: (2)

I don't know how you're struggling with this. Let's try again.

You said this. I'm directly replying to this statement. And I disagree with it. I don't want anything from you, except for you to realise I'm telling you that I disagree with this method. Some motors will not stay under this thermal time constant when set to 6A. They will overheat.

Bry195

im not struggling. I’m confident in the structure of my sentence and the concept it conveys. Is there a reason I should care more about your comment other than what I stated?

@ rcgod. makes perfect sense. you started with a higher timing that created a wider power curve. you lowered the timing and got more peak torque.

the reason someone would want higher peak torque over wider power is for a track that requires more acceleration and deceleration. If someone was interested in doing something similar to you they could run 10 short laps on an oval (just cones) and advance or retard the timing. the quickest time for all 10 laps will come from the timing that is best for acceleration and deceleration.

lowspark

iTrader: (7)

I find setting the amp draw vs timing to max rpm before it does not increase. Then back if off a touch. Track time will then dictate how the power works vs heat (gearing).
The part that makes sense is to measure this amp setting at X timing and note it down. So that when you clean, rebuild, install new bearings, you have a setting to match when you put it back together and drop it on the track again...

lowspark

iTrader: (7)

note that I use a GForce analizer to check the settings. I have started with using just a multi meter and trial and error LOL

Bry195

there are a couple shortcuts to get people close. Close is a relative term but lets define it as peak torque and really good efficiency.

set the timing to 40 degrees.
measuring time over a distance allows you to calculate speed.
speed of the chassis allows you to calculate rpm of motor.
if you run a 10 foot distance and calculate the average motor rpm it will be lower than average motor rpm of 100 foot because of acceleration and deceleration.

your fastest foot per second will come from an average rpm that is on the peak of power.
time 20 feet
startover and do 40, then 80 then whatever.

find the quickest average feet per second.
calculate the motor rpm for that quickest average.
that will be pretty close to the peak torque of that motor and because timing is at 40 it will be efficient as well.

now take what you learned about calculating feet per second and find the distance and time of your favorite track. what does the average speed néed to be in order to run say 400 feet in 10 seconds? 40 feet per second. take the motor rpm you calculated from the first test for peak power lets say it was 10000 rpm and calculate the gearing to run a motor at 10000 rpm 400 feet in 10 seconds. you will be pretty close unless traction is pretty bad.

if traction is bad then do the first test over again on that traction limited surface.

this is the same as using the tried and true method of running laps to a stop watch. a couple teeth up or down to get the motor to an average rpm that delivers the most power. the only difference is that when you are done you will calculate the RPM of the motor that did the best for you. you will take that motor rpm and use it as a starting point for other tracks.

you can play with timing to lower you peak torque and widen area under the curve to a point. outside of RC if you had to adjust to a track that you could not gear for you wouldnt change timing. you want peak torque in most situations so you pick a different motor that the peak torque can be used with a gearing change. a torque motor for short tracks and an rpm motor for longer tracks.

dont continue reading if you dont want to get confused. continue reading if you want to talk traction.

Im sure someone wants to talk about the effect traction has if you have a short track with a torque motor and the tires slip. the method to control slip isnt by minimizing peak torque and widening the curve although you can do that. the method outside of RC is in controlling the rate of acceleration and deceleration. Punch, brake rate, are single stage methods to control traction. because torque is not linear a single stage control for traction may not be enough. usually 3 points are enough to limit slip. an initial rate that requires more current because motor efficiency is low followed by a second stage because the motor will be moderately efficient (more torque for each unit of current) followed by a 3rd where you get lots of torque for every unit of current. outside rc this is called s-curve acceleration. its based on velocity not current though but you can figure out how you trigger finger introduces current at different rpms that increases velocity and torque. The multi point curves that allot of radios have is used to convert our current controlled esc into something that generates a linear velocity for a motor that has low efficiency at low rpm that gets very efficient as rpm goes up. my point is that these multi point curves can be used to take the friction in the chassis, non linear current efficiency, and limited traction and make the trigger linear to the track from a velocity perpective.

Coops500

Wow. That got serious very quick. Lol

oldfool

What did they draw out of the box, before you set the amp draw yourself?