Wattage calculation for gear box
11-08-2007, 08:31 PM
#1
Junior Member
Thread Starter
Join Date: Jan 2004
Location: Spokane,
WA
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Wattage calculation for gear box
Does anyone know of a wattage calculator that can be used with a brushless motor that is in a gear box. It is one thing to know how many watts per pound for an outrunner, but what about with a geared motor. The geared motor does not produce as many watts as say the same outrunner with the same prop\battery for the given range. Is there an easy to calculate the wattage based on the kv\#cells\gear ratio= wattage?????? I hope I have given you enough infor to understand what I am trying to figure out. I have such a calculator for electric heli's but what about planes.
Thanks in advance.....
Perry
Thanks in advance.....
Perry
11-10-2007, 08:57 PM
#2
My Feedback: (21)
Join Date: Jul 2002
Location: Spencerport, NY
Posts: 7,350
Likes: 0
Received 0 Likes
on
0 Posts
RE: Wattage calculation for gear box
Both Electricalc and Motocalc can handle gearboxes.
I'm not sure about your assertions about geared, motors, however. As a general rule, higher Kv motors, typically inrunners, are more efficient than lower Kv motors, typically outrunners, at the same power levels. Sure, you lose a little in the gearbox, but overall the efficiency is close to, or even better than, outrunners turning the same prop at the same RPM.
Additionally, because of the thicker wires in a high-Kv motor, you can put a lot more power through a lot lighter motor setup. People are finding that they can get incredible amounts of power from inexpensive CDROM motors, for example, by winding them for high RPM and using gearboxes.
I'm not sure about your assertions about geared, motors, however. As a general rule, higher Kv motors, typically inrunners, are more efficient than lower Kv motors, typically outrunners, at the same power levels. Sure, you lose a little in the gearbox, but overall the efficiency is close to, or even better than, outrunners turning the same prop at the same RPM.
Additionally, because of the thicker wires in a high-Kv motor, you can put a lot more power through a lot lighter motor setup. People are finding that they can get incredible amounts of power from inexpensive CDROM motors, for example, by winding them for high RPM and using gearboxes.
11-10-2007, 10:04 PM
#3
Senior Member
Join Date: Aug 2002
Location: West Middlesex,
PA
Posts: 868
Likes: 0
Received 0 Likes
on
0 Posts
RE: Wattage calculation for gear box
The bad thing about gearboxes is it gives you another instance for point of failure.
And don't forget that its gonna cost you more money if your dork you plane in fixing/replacing the motor power system.
Given the option of running an outrunner as compared to a motor w/gearbox, I'll take the outrunner every time.
Dave...
And don't forget that its gonna cost you more money if your dork you plane in fixing/replacing the motor power system.
Given the option of running an outrunner as compared to a motor w/gearbox, I'll take the outrunner every time.
Dave...
11-11-2007, 07:34 AM
#4
Senior Member
Join Date: Oct 2006
Location: CanberraACT, AUSTRALIA
Posts: 1,814
Likes: 0
Received 0 Likes
on
0 Posts
RE: Wattage calculation for gear box
Perry,
Motocalc will no doubt give you a real accurate answer. However, if you are just after back of the napkin accuracy then take the kv of your inrunner and divide it by your gearbox ratio - so, 4000kv inrunner with 4:1 gearbox = 1000kv at the prop shaft. Now go and look at some 1000kv outrunners, see what sort of props they turn and the amps they pull - that's a starting point for you.
Cheers,
Oz.
Motocalc will no doubt give you a real accurate answer. However, if you are just after back of the napkin accuracy then take the kv of your inrunner and divide it by your gearbox ratio - so, 4000kv inrunner with 4:1 gearbox = 1000kv at the prop shaft. Now go and look at some 1000kv outrunners, see what sort of props they turn and the amps they pull - that's a starting point for you.
Cheers,
Oz.
