Help! what motor to use in this plane

[Ronsplanes]

I need help with a clipped wing Mono coup balsa and covered no foam weight empty 1.5 LB's 36 " wing what size prop and motor can I use with a 3S 1300 lipo battery ?

I wanted to use the maximum amount of power that I can. I do not want a floater?

 

[DamoRC]

Ronsplanes,

Welcome to the forum.

When choosing a motor for your plane the first option should always be to find the same or similar model to yours and see what they are using. Often there is nothing new under the sun.

If you can’t find this information then your next step would be to use some of the common rules of thumb to determine which motor to use. A most useful “rule” is the watts-per-pound approach which works well for most situations. Here is a version of the rule;

• Less than 50W/lb - very lightweight / low wing loading slow flyer.
• 50 to 80 W/lb - light powered gliders, basic park flyers and trainers, classic biplanes and vintage ('Old Timer') type planes.
• 80 to 120 W/lb - general sport flying and basic/intermediate aerobatics. Many scale (egwarbirds) planes suit this power band.
• 120 to 180W/lb - more serious aerobatics, pattern flying, 3D and scale EDF jets.
• 180 to 200+W/lb - faster jets and anything that requires cloud-punching power

Using this rule I would suggest targeting 120 watts per pound (W/lb) to meet your desired flying characteristics.

Assuming an all up weight (AUW) of 2 lbs when battery, ESC, and motor are installed, you will be looking for a 240 watt motor.

Looking at the FT store you will see that this Emax motor and this FT Radial motor fit your needs well if you read the specifications and performance figures for each motor. Going with their suggested props should also work well for your needs and you should minimally have a 30A ESC for your setup.

I have not used the Emax motor but have been very happy with the quality and performance of the FT radial motor on similar planes with respect to weight and wingspan.

Of course there are many vendors with many motors to choose from and you can use the specs of the FT motors above to comparison shop.

Best of luck!

 

[Ronsplanes]

Ronsplanes,

Welcome to the forum.

When choosing a motor for your plane the first option should always be to find the same or similar model to yours and see what they are using. Often there is nothing new under the sun.

If you can’t find this information then your next step would be to use some of the common rules of thumb to determine which motor to use. A most useful “rule” is the watts-per-pound approach which works well for most situations. Here is a version of the rule;

• Less than 50W/lb - very lightweight / low wing loading slow flyer.
• 50 to 80 W/lb - light powered gliders, basic park flyers and trainers, classic biplanes and vintage ('Old Timer') type planes.
• 80 to 120 W/lb - general sport flying and basic/intermediate aerobatics. Many scale (egwarbirds) planes suit this power band.
• 120 to 180W/lb - more serious aerobatics, pattern flying, 3D and scale EDF jets.
• 180 to 200+W/lb - faster jets and anything that requires cloud-punching power

Using this rule I would suggest targeting 120 watts per pound (W/lb) to meet your desired flying characteristics.

Assuming an all up weight (AUW) of 2 lbs when battery, ESC, and motor are installed, you will be looking for a 240 watt motor.

Looking at the FT store you will see that this Emax motor and this FT Radial motor fit your needs well if you read the specifications and performance figures for each motor. Going with their suggested props should also work well for your needs and you should minimally have a 30A ESC for your setup.

I have not used the Emax motor but have been very happy with the quality and performance of the FT radial motor on similar planes with respect to weight and wingspan.

Of course there are many vendors with many motors to choose from and you can use the specs of the FT motors above to comparison shop.

Best of luck!

Thank you DamoRC I measured my Mono coup and its wing is 39" and the body 29" the empty weight is qpproxo,matley 2 LB's could probably addd another 1.5 LB's with the motor and gear all tucked in. heres some photos just taken of the plane.

 

[DamoRC]

Nice!

And it seems to have grown since the first post!

If it’s is currently complete except for motor, battery, and ESC then you are looking at maybe 10 more ounces given your choice of battery (1300mAh 3S) when you add these components. In this case my recommendation would not change much because I think if you move up a step in motor power your battery is going to struggle to keep up.

Assuming 20C for the battery (regardless of what the label says) you’ll be able to get maybe 25 amps max draw from the 1300mAh pack (approx 270 watts) at full throttle and at that rate you will get 2.5 mins flying time.

 

[quorneng]

Ronsplanes
To miss quote a famous line from the film Jaws at 3.5 lbs "You are going to need a bigger battery".
At least a 2200 mAh 3s, or maybe even 4s, along with an appropriate 350W motor.
At 3.5 lbs a 39" clipped wing Mono Coupe, like the full size, will be a 'hot ship'.

I notice you have posted an identical request under the "Everything Flight Test" heading. Simultaneous double posting is not a good idea. The same people are likely to see both and wonder if you are really serious. They might conclude a considered reply is a waste of their time.

 

[Ronsplanes]

Nice!

And it seems to have grown since the first post!

If it’s is currently complete except for motor, battery, and ESC then you are looking at maybe 10 more ounces given your choice of battery (1300mAh 3S) when you add these components. In this case my recommendation would not change much because I think if you move up a step in motor power your battery is going to struggle to keep up.

Assuming 20C for the battery (regardless of what the label says) you’ll be able to get maybe 25 amps max draw from the 1300mAh pack (approx 270 watts) at full throttle and at that rate you will get 2.5 mins flying time.

I'm starting out with a 3S Lipo 1600 Mah I'm hoping Ill get at least 6 minutes out of it in flight.