Motor size vrs. prop size

R

ram1000

Well-Known Member
Is there an explanation of motor sizes and the relation between a number (2213 or xxxx) and the kv and prop size usable with these motors?
 
ram1000 said:
Is there an explanation of motor sizes and the relation between a number (2213 or xxxx) and the kv and prop size usable with these motors?
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The first number has to do with the torque, and the second with RPM per Volt (k/v)

Usually you use the wattage and KV to decide what a motor can do.
 
GJH105775 said:
The first number has to do with the torque, and the second with RPM per Volt (k/v)

Usually you use the wattage and KV to decide what a motor can do.
Click to expand...

Huh. I was under the impression that the first number, 2213, was the size of the motor. In this case; 22mm in diameter with a magnet 13mm high. I was also under the impression that a formula involving amp draw and KV was how to determine torque ( efficiency measured as lbs/hp ) for A/C motors and thrust is the measure of horsepower. Now I'm confused. Please help.
 
I just went and measured a 2216 motor I have loose and sho 'nuff it's 22mm in dia. and the magnet is 16mm. I still need to research the torque, horsepower measurement. I am also curious how wattage relates. Nuts. I thought I had this down. Google here I come!! Haha!
 
HDtallrider said:
I just went and measured a 2216 motor I have loose and sho 'nuff it's 22mm in dia. and the magnet is 16mm. I still need to research the torque, horsepower measurement. I am also curious how wattage relates. Nuts. I thought I had this down. Google here I come!! Haha!
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Hahaha, in general the bigger the diameter of the bell the more torque(just using torque though that is not the proper measurement) the motor will have, same with the magnets (the relation between the two also affects the frequency of the phasing). The wattage is how many amps the motor can do at the said voltage before the coils burn up.
 
Hi guys motor numbers are can size 22mm x 16mm, the kv is the rpm per 1 volt of power , the lower the KV the more torque it has the bigger prop it can spin
 
Hope this helps.

The Kv is simply the RPM the motor will spin (unloaded), given one (1) Volt. Meaning, if the motor is a 1000Kv motor, then if a voltage of 10V is applied, the motor will spin 1000 RPM/V x 10V = 10,000 RPM.


The efficiency is the propeller blade, motor, and ESC all in combination, and it’s the amount of thrust generated per amount of input energy (Watts).


In this regard, efficiency in Metric units is grams / Watt.


Efficiency in Imperial unit is lbs / hp.


Watt and hp are just different units of the same thing, aka, energy.


Lbs and gram are just different units of the same thing, aka, force (thrust).


Thanks,

Patrick Koegler

Owner, KDE Direct

To clarify further I called and was told that considering the KV rating of a motor as the only measure of torque is oversimplification. He went on to say that for general help in choosing a motor for a quad it can be used as a guide. Lower KV will swing a larger prop and create more lift more efficiently than a higher KV motor swinging a smaller prop. I left it there because it was getting into confusing technical stuff after that.
 
xD Hahaha, exactly. You can have a big commercial 1000kv motor that would weigh a hundred pounds and drive a lot more because of the wattage. Also many trains are driven by brush-less motors powered by generators that are powered by diesel.
 
Haha! The train analogy was one used as the discussion started to head into really technical stuff. That's about when my eyes glazed
over..........
What I came away with is that for our purposes in trying to put together the right motor and prop combinations, using the KV as a signifier of torque is an easy short cut. Something lay people like me can understand. The engineer I spoke with constantly emphasized the important roll the ESC plays. He went on to explain why they went with a clean slate design and talked about avoiding built in BEC's and how they affect the performance of the ESC, depending on the amount of amps being drawn. I got lost right after "hello"........ Hahaha!
 
HDtallrider said:
Haha! The train analogy was one used as the discussion started to head into really technical stuff. That's about when my eyes glazed
over..........
What I came away with is that for our purposes in trying to put together the right motor and prop combinations, using the KV as a signifier of torque is an easy short cut. Something lay people like me can understand. The engineer I spoke with constantly emphasized the important roll the ESC plays. He went on to explain why they went with a clean slate design and talked about avoiding built in BEC's and how they affect the performance of the ESC, depending on the amount of amps being drawn. I got lost right after "hello"........ Hahaha!
Click to expand...
Hahahahaha
 
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