OlliePackman
Active member
How do you calculate the size of the required prop for a motor? For example I want a 2840 1800kv motor on a 50a esc with 2200mah 3s on my motor glider. What size prop would be required here?
Solved How to know what prop size
- Thread starter OlliePackman
- Start date
TheFlyingBrit
Legendary member
Your prop specification is normally dictated by your motor size and current draw. It is usually supplied with your motor depending which battery size option it suggests.
Turnigy do a LDA2840A motor which is 400watts, you could get away with a 40amp ESC on that as it only draws around 30 amps max.
That motor runs anything from a 2s to 4s battery. However, using a 3s battery I would look at a 7x6 APC prop to start with and use a power meter to check out the motor as it ramps up to full speed (The 50 amp ESC is more than you would need, but will do the job better being over spec).
I certainly wouldn't go any higher than a 8x4 prop.
Turnigy do a LDA2840A motor which is 400watts, you could get away with a 40amp ESC on that as it only draws around 30 amps max.
That motor runs anything from a 2s to 4s battery. However, using a 3s battery I would look at a 7x6 APC prop to start with and use a power meter to check out the motor as it ramps up to full speed (The 50 amp ESC is more than you would need, but will do the job better being over spec).
I certainly wouldn't go any higher than a 8x4 prop.
quorneng
Master member
The only safe way to safely confirm the prop you chose is not over loading the motor or the ESC is to use a Watt meter. It will measure the amps actually being used.
Cheap enough to buy and if it saves you burning out an ESC or motor it is well on the way to paying for itself.
I use one of these bought off ebay.
You do have to solder on connection to suite your battery and motor connectors. More expensive version may give a choice of connectors.
Cheap enough to buy and if it saves you burning out an ESC or motor it is well on the way to paying for itself.
I use one of these bought off ebay.
You do have to solder on connection to suite your battery and motor connectors. More expensive version may give a choice of connectors.
TheFlyingBrit
Legendary member
I did mention in my post to use a power meter to check the motor as it ramps up ! Watts is the unit of power (so Watt meter or Power meter same thing)
. if it doesn't give a direct current reading (most do) you can calculate it from the voltage used and watts produced, current (A) =Watts/Volts.
TheFlyingBrit
Legendary member
One good rule of thumb start with a smaller prop and work up, its less load on the motor and ESC.
TheFlyingBrit
Legendary member
OlliePackman
Active member
There are no reccomended props on this motor that's why I asked
OlliePackman
Active member
That's a smaller prop than I was expecting. Would you say this setup would be suitable for a simple soarer?
TheFlyingBrit
Legendary member
The LDA2840A is also an 1800kv motor same as yours I would try the 7x6 with a 3s and to be on the safe side check your current with a power meter, it shouldn't exceed 30 amps.
I have one similar to this, they are not that much to buy and can save you a lot of expense in the long run.
I have one similar to this, they are not that much to buy and can save you a lot of expense in the long run.
TheFlyingBrit
Legendary member
The lower a KV the more thrust, therefore the props tend to be bigger, the higher your KV the more speed hence smaller props. For example the MT1806 is 2280kv and uses a 5" or 6" prop (commonly used on the Tiny trainer), the CF2822 1200kv motor will probably use an 8 or 9" prop they where classed as B type motors and where used on simple cubs.
so your motor being an 1800kv I would guestimate with a 3s battery that a 7" prop would be in the right ball park.
so your motor being an 1800kv I would guestimate with a 3s battery that a 7" prop would be in the right ball park.
