Appropriate prop for my Super Scout XL electros???

[SEEBO]

I've been playing around with some of the various free prop calc websites and I've got some pretty wide swings in answers. I have a motor/esc combo from a wrecked Eclipson plane and I want to put it in my Super Scout XL SBK. Its a Sunnysky X series motor 2814 1250kv and a Hobbywing Skywalker V2 50a ESC. I've had one prop calc site tell me I need a 9 x 6 and I've also had 10 x 5 and even the Flite Test store page says a 12 x 4.5. I have plenty of both 4s and 3s batteries although I'm anticipating this plane running solely on 4s. I'm still a student of prop math so I'm hoping the hive mind can point me in the correct direction. Thanks in advance for the help folks!

 

[Piotrsko]

Your prop limiting is governed by how many watts the esc can switch, how much heat the motor tolerates, how much battery you have to push electrons through the system. Too hot and magic smoke escapes. Sometimes you can abuse stuff for a long time, sometimes it's just once. Go find the order page online for the motor, they usually give a reccomended prop, or find a similar sized motor and use what that recommends. You may not use the recommended size but it is a statting point larger diameter needs smaller pitch, smaller diameter needs more pitch

 

[SEEBO]

Yeah I have a ton of 9x4.5 from my other models I may try out. Also have 1 or 2 10x5 sitting around. May try some bench tests with it and do some probing with a multimeter.

 

[quorneng]

SEEBO
Be aware there is no perfect prop for a particular motor as it significantly depends on the plane you are going to use it on and how you want it to fly.
As Piotrsko has pointed out of more significance are the physical limitations of the motor, ESC, battery and in extreme cases even the size of the wiring.
The maximum amps the motor can stand are given as 55A for 15 seconds. It is amps that damages the motor not the volts
You would need a 70A ESC to safely handle that level of amps. Overload an ESC by much either amps or volts and it is wrecked - instantly!
The recommended props are 8x6 & 9x6.

How close to the maximum amps you will get on each prop will depend on the voltage of the battery (number of cells) and its capability (C rating).
To ensure you don't actually damage/wreck anything it is worth investing in a Watt meter. This will measure the amps the battery is giving in real time so if on test you find that the amps are getting close to the maximum then stop! Either use a lower cell battery or fit a a smaller or less pitch prop and try again..
If you operating well below the maximum motor amps then the best prop will be down to you actually flying the plane with props of different diameter and pitch to see what gives the plane that best characteristics you are looking for like speed, take off performance, climb rate or battery endurance. No one prop will give the best of all of them.

Unless you are expert in flying that particular plane it is quite likely you will find it hard to tell the difference between some of the props so by far the easiest solution is to fit the recommended prop, motor and battery for the plane and then fly it until you can tell the difference with different props.

I hope this helps.

 

[SEEBO]

SEEBO
Be aware there is no perfect prop for a particular motor as it significantly depends on the plane you are going to use it on and how you want it to fly.
As Piotrsko has pointed out of more significance are the physical limitations of the motor, ESC, battery and in extreme cases even the size of the wiring.
The maximum amps the motor can stand are given as 55A for 15 seconds. It is amps that damages the motor not the volts
You would need a 70A ESC to safely handle that level of amps. Overload an ESC by much either amps or volts and it is wrecked - instantly!
The recommended props are 8x6 & 9x6.

How close to the maximum amps you will get on each prop will depend on the voltage of the battery (number of cells) and its capability (C rating).
To ensure you don't actually damage/wreck anything it is worth investing in a Watt meter. This will measure the amps the battery is giving in real time so if on test you find that the amps are getting close to the maximum then stop! Either use a lower cell battery or fit a a smaller or less pitch prop and try again..
If you operating well below the maximum motor amps then the best prop will be down to you actually flying the plane with props of different diameter and pitch to see what gives the plane that best characteristics you are looking for like speed, take off performance, climb rate or battery endurance. No one prop will give the best of all of them.

Unless you are expert in flying that particular plane it is quite likely you will find it hard to tell the difference between some of the props so by far the easiest solution is to fit the recommended prop, motor and battery for the plane and then fly it until you can tell the difference with different props.

I hope this helps.

It absolutely helps and thank you both for the info. Since I made this thread I've done some deep digging and as I type this my 3D printer is making a thrust force meter with a built in Watt meter so I can monitor various parameters and help me dial in the ideal prop for the capabilities of my electronics.

 

[Piotrsko]

Change that to range of props. One will never be the best by itself because of atmospheric differences. Will be really close.

 

[SEEBO]

Change that to range of props. One will never be the best by itself because of atmospheric differences. Will be really close.

Noted! Thanks again for the input guys!