Power, Torque. 9L vs 10L
 

Hello,

I'm a little confused and hoping someone can set me straight. I know that a 9L has a higher number of revolutions per volt than a 10L but which has more torque assuming the SAME input voltage?

For some odd reason I always thought (with brushed motors) that lower winds had more RPM but less torque. Recently I was told that is incorrect, a 10turn brushed has more torque than a 12turn brushed. I'm wondering which is the case in brushless.

Thanks!

DM

That is incorrect.

I have the 10L Feigao in my Hyper 7 PBS and it flies on 12 cells. Lots of torque and speed.

http://www.rcuniverse.com/magazine/a...article_id=467

So which has more torque the 9L or the 10L.

They can't be much differant from each other. I think the 9l would have more torque because its higher kv rating. But that is just a guess.

it depends on how many cells you run the motor on

Like I said, assume the same voltage. Which one has more Torque. There has to be a chart of this kind of thing somewhere...

Both have got the same torque. (the power the magnet can translate from electric energy into torque is the same)

the 9L will turn faster and can be geared a bit higher. the 10L will give you a longer runtime though and will run cooler.

9L and 10L are rated to the same maximum power.

But power is torque*RPM, so 9L has less torque then 10L.

Artur

This is the wall I've come up against. One guy says one thing and another says the oposite.

If

Power = Torque * RPM

Then

Serum is right and GriffinRU is wrong and the 9L has more Power

Or

GriffinRU is right and Serum is wrong and the 9L has less Torque.

I'm sorry to play you guys off eachother but the two statements can't be right unless the equation is wrong. I had a 9L which died and now I've got a 10L, I'm getting ready to replace it but I'm not sure which to get. Just thought knowing torque would simplify the purchase decision.

if you want more torque than go with an xl motor.

the maximum power the magnet can handle is reached at a certain point. at this point, both motors will have got the exact same torque because they use the exact same protocol to translate the electric magnetic energy into torque..

if this is neglected, or if this 'satisfaction' point is not reached, then yes, a 10L will have more power.

Well if the power = torque x Rpm The 10 L would have more torque at the same power for it has a lower rpm.
I think the 10L may have it by a fraction but it is not a great deal. The question would really matter is the amount of cells you have or plan to run.

Keep in mind that - The lower turn motor will give less runtime and get hotter quicker.

It all depends on how many cells you attach to motor...

For a example (not true for given motors, do not have datasheets):
At 12 cells 9L can produce more torque then 10L, but at 16 cells it would be opposite. In first case 10L doesn't have enough current to generate torque, while 9L is a top performance, in the second case 10L gets to its top - while 9L past sweet spot. So in first case 10L stays cool and acceleration sucks and in the second one 9L overheats (efficiency down, excessive current draw...) while 10L runs normal.

Artur

P.S. Check labels on both motors for current ratings, 9L has higher numbers, because rated for lower voltage at the same can size (rated can power)

What are the torque defining parameters?

Magnet size, Number of turns and core size
Both motors have the same size magnet and same core size. Motors with higher number of turns have more torque, with less have higher RPM at given Voltage all the rest is efficiency!

RIGHT!

and when they turn their energy almost directly into heat, you know that the satisfaction point of the magnet is reached.


if you calculate it back, the same motors from a serie with another winding will have the same power.

Here, take a look at these measurements;

http://www.lehner-motoren.com/diagra....18v_liste.txt

http://www.lehner-motoren.com/diagra....18v_liste.txt

if you look at the poweroutput of both motors and take a look at the 800watt line, you'll see that the 1940/10 has got 28.7 N/cm of torque and the 1940/12 has got 34.05 N/cm of torque. and if you take another look at the RPM's, you'll see that the the 1940/10 delivers 28.7@26797rpm and the 1940/12 34.05@22674.

these values mean, that the motor can lift;

28.7N@101km/h
34.5N@85km/h




so the motors will deliver about the same power, but the 10L will have got more torque (untill it reaches the satisfactionpoint of the power of the magnet) then, both motors will have the same power. but with this higher torque, comes a lower RPM, and RPM X Torque = POWER and you don't run your car on torque, but on power.

Well If the formula is right power = torque x rpm The 10l has it beat. The 10l has lower kv so it takes more torque to equal the same power.

I put an 8L in my EMaxx today it is insane. I have a 10L in my 1/8 scale buggy and it is just as insane but the 8L is a bit fast because higher kv per cell.I am temped to try to find a 10L with a 1/8 shaft if I could and use it in my EMaxx for the better run time.

@leroy, that is exactly my point. same power.

and you don't run a car on torque or on RPM, it's a mixture of both.

As a Look-Up Table
 

Torque Down < decrease < Number of turns > increase > Torque Up

Torque Down < decrease < Can (Core) Diameter > increase > Torque Up

Torque Down < decrease < Can Length > increase > Torque Up

Torque Down < decrease < Magnet Size > increase > Torque Up

Artur

Just for the record artur, I agree with everything you say here. BUT, the torque a motor needs to produce depends solely upon the load put upon it. The factors you hightlighted (number of turns, can diameter, can length, magnet size) affect the 'kt' of a particular motor. The 'kt' of a motor will affect how much current the motor will need to draw to produce enough torque to overcome that load.
Not critizising you; just trying to clear this up for everyone else

ps. to all those people who say 'if this formula is correct; power = torque x rpm' - there is no 'if' about it. This formula stems from moment calculations in physics, and believe me its correct!

It sure is maxxdude.. It sure is..
and that is the reason why i keep saying it's NOT ONLY about torque.

It's the mixture of torque AND rpm..

TORQUE determines the TIME the car needs to get to topspeed

and BHP (watts) determines the TOPSPEED of the car.

together with a whole lot other variables, but this is about torque and motors, so this is the thing that is relevant, without getting into useless details.


And in RC, you can take a 9L. and if you want more runtime, take a 10L...

If you want noticable more torque, get an XL.

Well to this table right here is right the 10 L has more torque to.
I think the 9l or 10l has a good torque but it would depend alot on the runtime and batteries to which one i would run. the 9L on 16 cells would have good power but would suck cause of heat issues.

like i said earlier if you want more torque just go with an xl size motor

http://www.rc-monster.com/forum/show...?t=2689&page=2

Artur