Foam Addict
Squirrel member
Hey all,
I am almost as obsessed with the motor and propellor theory side of this hobby as the building and flying side, and since there aren't a lot of motor experimentation/ basic info threads around, I decided I would compile some basic rules and tricks here.
Please add to this list with your own observations, this is a Noob's guide to motors and props
My sources are Rcgroups, The Ezone, and personal experimentation.
This is the Chart I usually use for powering my planes, sourced from Pat Mattes Ezone articles:
A 25 watt per pound (final weight) airplane is typically hand-launched, and not terribly aerobatic. 50 watts per pound gives you a nice flying airplane that will take off of pavement and do loops, rolls, etc. 75 watts per pound will take off in grass. 100 watts per pound gives you an airplane that will go vertical.
I find these rules to be very accurate for 5-15 oz/sq Ft. Wing loading, above that add 25 watts to these numbers.
Also, links for rewinding motors:
http://www.rcgroups.com/forums/showthread.php?t=1456812
Some rules for motors:
Ohm's Law: Remember V=IR. There is no such thing as a free lunch, but increasing voltage to a motor is close to one. Adding voltage will increase power for very low heat increase, albeit at a weight expense.
Lower KV/higher gearing+higher voltage=More voltage for fewer amps for the same power draw.
A couple of basic rules for props: larger, slower turning props with a higher pitch tend to be more efficient than smaller, faster turning props with a lower pitch.
APC electric props are usually more efficient than Slow fly props, and unload less in the air, leading to higher thrust and amp draw than Master Airscrew props.
Fewer blades are more efficient than than more blades.
I am almost as obsessed with the motor and propellor theory side of this hobby as the building and flying side, and since there aren't a lot of motor experimentation/ basic info threads around, I decided I would compile some basic rules and tricks here.
Please add to this list with your own observations, this is a Noob's guide to motors and props
My sources are Rcgroups, The Ezone, and personal experimentation.
This is the Chart I usually use for powering my planes, sourced from Pat Mattes Ezone articles:
A 25 watt per pound (final weight) airplane is typically hand-launched, and not terribly aerobatic. 50 watts per pound gives you a nice flying airplane that will take off of pavement and do loops, rolls, etc. 75 watts per pound will take off in grass. 100 watts per pound gives you an airplane that will go vertical.
I find these rules to be very accurate for 5-15 oz/sq Ft. Wing loading, above that add 25 watts to these numbers.
Also, links for rewinding motors:
http://www.rcgroups.com/forums/showthread.php?t=1456812
Some rules for motors:
Ohm's Law: Remember V=IR. There is no such thing as a free lunch, but increasing voltage to a motor is close to one. Adding voltage will increase power for very low heat increase, albeit at a weight expense.
Lower KV/higher gearing+higher voltage=More voltage for fewer amps for the same power draw.
A couple of basic rules for props: larger, slower turning props with a higher pitch tend to be more efficient than smaller, faster turning props with a lower pitch.
APC electric props are usually more efficient than Slow fly props, and unload less in the air, leading to higher thrust and amp draw than Master Airscrew props.
Fewer blades are more efficient than than more blades.
