Prop sizing

[Fred Flintstone]

Is there any info on different props for different motors, weights, etc. I've seen 2 blade and 3 blade props on the same type of machines. Whats the difference between props? I know the part # has something to do with the size of the prop, but not sure what the numbers mean. I think it would be helpful for a newbie to be able t understand this.

 

[dotbox]

Essentially, the first number is the length of the prop or the diameter of the circle made by it in rotation the second number is the distance that the prop will move forward through the air in one rotation.
http://www.rc-airplane-world.com/propeller-size.html

 

[Paul-H]

Also the same motor need different size props depending on the number of cells in your pack

More cells = higher RPM which = smaller diameter prop ie 3 cell pack motor uses 10inch prop but use a 4 cell pack on the same motor and you have to drop to a 8 or 9 inch prop.

Best to test your chosen motor, esc and prop on a Watt meter to ensure you are not drawing too much current for the motor and esc and ensure your combined motors and esc's current draw does not exceed the max c discharge rate of your battery pack. Its all a bit of a balancing act, talking of which, don't forget tobalance your props as well.

Paul

 

[dotbox]

Also the same motor need different size props depending on the number of cells in your pack

More cells = higher RPM which = smaller diameter prop ie 3 cell pack motor uses 10inch prop but use a 4 cell pack on the same motor and you have to drop to a 8 or 9 inch prop.

Best to test your chosen motor, esc and prop on a Watt meter to ensure you are not drawing too much current for the motor and esc and ensure your combined motors and esc's current draw does not exceed the max c discharge rate of your battery pack. Its all a bit of a balancing act, talking of which, don't forget tobalance your props as well.

Paul

Who has a Watt meter? I, myself and an associate have used 8-9" props on 3-cells without problems. I don't know how that works out mathematically, but nothing smokes or drop to the ground. I was told larger props 9-10's need to be driven by lower kv (750-800) for 3 cells for decent output duration. I don't know how that works out on paper, but it seems to be functional, but I'm not flying mini's either.
Maybe I've just be really lucky for being so stupid. I can accept that. ;-)

 

[Paul-H]

For the minimal cost that a watt meter costs (£5 to £6) knowing that everything is balanced and within spec is not a bad thing.

Getting everything balanced can greatly extend your flight times and enjoyment and can save premature failure because something is run constantly at its limits or just above.