Props
- Thread starter rwilabee
- Start date
Vortex
Member
I was always taught to multiply the diameter by the pitch to give you a PF or Power Factor. The higher the PH the more load will be exerted on the motor and hence the current draw will increase and the battery will not last as long.
Bigger diameter props like to rev slower where the smaller diameter will be more efficient with higher rpm. Check the motor Kv/rpm to see what is the maximum for your motor and then check the actual rpm which will give you a good starting point. Then you can look at current draw and you have something to start working with.
9 x 5 gives a PF of 45
10 x 4.7 gives 47
It's a rough guide but has always worked for me....
Regards,
Lance
Bigger diameter props like to rev slower where the smaller diameter will be more efficient with higher rpm. Check the motor Kv/rpm to see what is the maximum for your motor and then check the actual rpm which will give you a good starting point. Then you can look at current draw and you have something to start working with.
9 x 5 gives a PF of 45
10 x 4.7 gives 47
It's a rough guide but has always worked for me....
Regards,
Lance
Macsgrafs
Active Member
Well I learn something new everyday, thanks Lance....you were my lesson for today..PF.
So my 12 x 6 props have a PF of 72 & if I went to 14 x 4.7 I would have a PF of 65.8, so I might be better off with a larger prop, but it takes longer to spin up & my octo would be less responsive??
Ross
So my 12 x 6 props have a PF of 72 & if I went to 14 x 4.7 I would have a PF of 65.8, so I might be better off with a larger prop, but it takes longer to spin up & my octo would be less responsive??
Ross
Interesting. Is there a multiplier for 3-blade propellers? I've read (on the internet, so it must be true!) that the rule of thumb in comparing 3-blades to 2-blade props is to 1ncrease the 3-blade's diameter by 1" and decrease it's pitch by 1. So a 9x5x3 prop would be comparable to a 10x4 2-blade prop.
Does the same hold true for the PF rule of thumb?
Quick & easy calculations like these are super helpful.
Does the same hold true for the PF rule of thumb?
Quick & easy calculations like these are super helpful.
Vortex
Member
Hey Ross.....Happy to be able to help
Basically the answer is yes. There are a lot of factors at play and at this point an ammeter is your friend and a very useful tool to see if you are nearing the maximum motor load.
Regarding 3 blade props I have heard the same thing but not having spent a lot of time playing with 3 bladed props I am not able to help a lot.
Regards,
Lance