Question on Motor,prop size and Pitch

[shoyn]

Hi all. Recently got advice from 14 Blades and sun storm.

Normally prop size goes like this:
28mm motors
800 - 900kv = 12 to 13 inch prop
1000-1100KV = 11 to 12 inch prop
1000-1100KV = 10 to 11 inch prop
1100-1200KV = 9 to 10 inch prop
1200-1300KV = 8 to 9 inch prop
1300-1400KV = 7 to 8 inch prop
1500-1600KV = 6 to 7 inch prop

35mm motors
800 - 900kv = 13 to 14 inch prop
1000-1100KV = 12 to 13 inch prop
1000-1100KV = 11 to 12 inch prop
1100-1200KV = 10 to 11 inch prop
1200-1300KV = 9 to 10 inch prop
1300-1400KV = 8 to 9 inch prop
1500-1600KV = 7 to 8 inch prop

Credits to 14 Blades

And from what sunstorm said, higher KV motor and higher pitch increases the speed of the plane.

But i am still not sure of motor kv suits what prop size and pitch? Then also how do you determine the KV of a motor if the manufacturer had not stated it on the motor. Thank you. Hope this can be a guide too to all those who are new to the hobby and would like to know what prop size and pitch complements with the motor.

[foxkilo]

Hmmm... normally if I'm using the garden-variety about 1000+KV brushless motor, I limit the prop diameter to 8 inch, so 8x4 or 8x6, esp if using 3S lipo. So far, so good. 9 inch diameter is the largest I would use with 2S.

There are many parameters coming together, so the best way is to get a wattmeter and bench-test your electronics setup. Even the motor spec data sheet cannot be fully relied on, sometimes.

[Sunstorm]

Hello.

Well, why don't you download this software.

http://www.drivecalc.de/

From there, just pick and choose a motor, and prop. It would give you an ESTIMATE of the amps drawn, pitch speed and thrust.

If your motor is not listed, just pick a similar motor to it in terms of weight and KV.

Then also how do you determine the KV of a motor if the manufacturer had not stated it on the motor.

You use a KV meter which is sold in our local hobby stores

[shoyn]

Thank you for the reply. Yup, got myself a watt meter. But how would know the maximum wattage the motor can withstand if the manufacturer does not state it on the motor?

Thanks sunstorm, will definitely put the software to good use. What do you mean by weight? Then also must the motor size and shaft diameter be considered too?

[Sunstorm]

some motors have different naming convention. E.g. axi 2820 and turn igy 3542 is the same size. Weight is one way you can 'see past' the different naming conventions. they both weight about 130 - 140 gms if i recall.

play around with the software, in time you would get it. Shaft size is not that relevant where that software is concerned.

[shoyn]

I see. By the way how would know the maximum wattage the motor can withstand if the manufacturer does not state it on the motor? Can i use the software to find what type of motor is suitable for what type of prop size?

[Sunstorm]

I see. By the way how would know the maximum wattage the motor can withstand if the manufacturer does not state it on the motor?

I don't know, but the software has some guidelines

Can i use the software to find what type of motor is suitable for what type of prop size?

Yes, play around with it already!

[shoyn]

Playing with it now.