Help electric motor size for 46 size trainer
08-01-2013, 08:50 AM
#1
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Help electric motor size for 46 size trainer
Can someone help determine electric motor and esc size for a balsa 46 size high wing trainer that weighs 5 - 6 lbs. Thanks batdog
08-07-2013, 10:25 AM
#3
EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.wattflyer.com/forums/showthread.php?t=31368
http://www.rcuniverse.com/forum/m_7100376/tm.htm
See the chapter on sizing electric power systems.
You would want to target approximately 100 watts/pound
e-flite has a Power 46 motor that will likely work for you
http://www.horizonhobby.com/products...70kv-EFLM4046A
http://www.wattflyer.com/forums/showthread.php?t=31368
http://www.rcuniverse.com/forum/m_7100376/tm.htm
See the chapter on sizing electric power systems.
You would want to target approximately 100 watts/pound
e-flite has a Power 46 motor that will likely work for you
http://www.horizonhobby.com/products...70kv-EFLM4046A
08-07-2013, 01:04 PM
#4
For a trainer you could install a power 32, 40 , or 46 size motor. An Eflite Power 46 and an Eflite 60amp ESC would work and would give you the extra power if you wanted to convert it to a float plane, ski plane, etc... You could also put in a Power 32 /equivalent and that should fly it as a trainer. If you don't want to spend that much on Eflite then you could try motors from here
I would run the Power 46 on a 4-cell LiPo with a 13X6 prop and a Power 32 on a 4-cell Lipo with an 11x7 or 12x6 prop.
I would run the Power 46 on a 4-cell LiPo with a 13X6 prop and a Power 32 on a 4-cell Lipo with an 11x7 or 12x6 prop.
08-12-2013, 10:59 AM
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Try the Hobbyking NTM 3548-900KV with a 4 cell 3000-4000MAH battery and an APC 13x6.5 prop. I use the DETRUM ESC because it has a switch mode BEC, you can het that from HobbyPartz.com. I've been using this setup for the last 2 years and have been very satisfied with it. D.H.
09-12-2013, 11:03 PM
#6
Senior Member
If the trainer's all up weight is say 6lb.
The rule of thumb is about 100W per pound for "gentle" non aerobatic flying.
150W per pound for mild to moderate aerobatics.
~200W for 3D
An E-Flite power 32, if memory serves, is a 600W motor.
An example of a trainer might be an Alpha 40 ARF trainer. (Horizon Hobby)
Listed weight 5.25 lb .40 2cy Glow E Flight Power 25 motor, 3or 4C LIPO, 60A ESC
This particular model may need to have weight added to the nose for electric power, or move the wing back about an inch or so.
It flies quite well with a power 25 or 32. A three bladed 12" prop may be needed for grass fields.
A Power 46 is usually used for about a 7lb model.
I like the Power 52, for 10-11lb models and a 6C LIPO
Another rule of thumb is to use around 9,000 - 10,000 RPM as a rough guide for the E-Flite 25 and 32 motors
The bigger motors seem to be happy ~8,000 - 9,000 Has to do with voltage and prop size.
The rule of thumb is about 100W per pound for "gentle" non aerobatic flying.
150W per pound for mild to moderate aerobatics.
~200W for 3D
An E-Flite power 32, if memory serves, is a 600W motor.
An example of a trainer might be an Alpha 40 ARF trainer. (Horizon Hobby)
Listed weight 5.25 lb .40 2cy Glow E Flight Power 25 motor, 3or 4C LIPO, 60A ESC
This particular model may need to have weight added to the nose for electric power, or move the wing back about an inch or so.
It flies quite well with a power 25 or 32. A three bladed 12" prop may be needed for grass fields.
A Power 46 is usually used for about a 7lb model.
I like the Power 52, for 10-11lb models and a 6C LIPO
Another rule of thumb is to use around 9,000 - 10,000 RPM as a rough guide for the E-Flite 25 and 32 motors
The bigger motors seem to be happy ~8,000 - 9,000 Has to do with voltage and prop size.
Last edited by chuckk2; 09-12-2013 at 11:09 PM.
09-13-2013, 06:18 AM
#7
If the trainer's all up weight is say 6lb.
The rule of thumb is about 100W per pound for "gentle" non aerobatic flying.
150W per pound for mild to moderate aerobatics.
~200W for 3D
An E-Flite power 32, if memory serves, is a 600W motor.
An example of a trainer might be an Alpha 40 ARF trainer. (Horizon Hobby)
Listed weight 5.25 lb .40 2cy Glow E Flight Power 25 motor, 3or 4C LIPO, 60A ESC
This particular model may need to have weight added to the nose for electric power, or move the wing back about an inch or so.
It flies quite well with a power 25 or 32. A three bladed 12" prop may be needed for grass fields.
A Power 46 is usually used for about a 7lb model.
I like the Power 52, for 10-11lb models and a 6C LIPO
Another rule of thumb is to use around 9,000 - 10,000 RPM as a rough guide for the E-Flite 25 and 32 motors
The bigger motors seem to be happy ~8,000 - 9,000 Has to do with voltage and prop size.
The rule of thumb is about 100W per pound for "gentle" non aerobatic flying.
150W per pound for mild to moderate aerobatics.
~200W for 3D
An E-Flite power 32, if memory serves, is a 600W motor.
An example of a trainer might be an Alpha 40 ARF trainer. (Horizon Hobby)
Listed weight 5.25 lb .40 2cy Glow E Flight Power 25 motor, 3or 4C LIPO, 60A ESC
This particular model may need to have weight added to the nose for electric power, or move the wing back about an inch or so.
It flies quite well with a power 25 or 32. A three bladed 12" prop may be needed for grass fields.
A Power 46 is usually used for about a 7lb model.
I like the Power 52, for 10-11lb models and a 6C LIPO
Another rule of thumb is to use around 9,000 - 10,000 RPM as a rough guide for the E-Flite 25 and 32 motors
The bigger motors seem to be happy ~8,000 - 9,000 Has to do with voltage and prop size.
A very standard recommendation is 100 watts/pound as more than enough for sport aerobatics on most planes. Of course, again, how do you define sport aerobatics?
When people are converting from glow, 100 watts/pound is typically what is recommended. 150 watts/pound will hover almost any aircraft.
Now, if you are in competition and feel you want more power reserve, that is fine. But I do want to put a little context to these power discussions. Having extra is not a problem.
The downside is usually more weight and cost. You will need a bigger motor, bigger ESC and bigger or higher C rated battery to support higher powered systems.
Last edited by aeajr; 09-13-2013 at 06:35 AM.
09-13-2013, 07:30 AM
#8
Senior Member
From E-Flite Power 46 data
Up to 800W
From Power 32 data
Ideal for 30- to 36-size sport and scale airplanes weighing 3.5 to 6 pounds (1.6 to 2.7 kilograms), 25- to 36-size 3D airplanes up to 4.5 pounds (2-kilograms), or models requiring up to 800 watts of power.
From Power 25 data
Ideal for 25-size sport and scale airplanes weighing 3- to 5.5-pound (1.4- to 2.5-kilograms) 15-size 3D airplanes up to 3.5 pounds (1.6 kilograms), or models requiring up to 600 watts of power.
(My memory was placing the 32 at 600W)
Anyway, these are maximum watt ratings, not continuous.
I generally consider sport as the minimum level to have as a goal.
Besides sheer power, you also have to consider such things as wing loading as well as overall weight and the desired performance.
Even with a trainer, it's better to have at least a 1:1 power weight ratio. An argurment concerning this has existed
I prefer to set up for more power in order to allow for a short ground roll, rapid climb out, etc.
(Planes belong in the air, not trundling along in the grass!)
Electric Motors, when chosen properly, and with the correct prop can get (in theory) fairly high efficiency, say in the 80's.
There are some practical limits as well. Most ESC's are rated for 4C LIPO's. 6C rated ones are more expensive.
With all the variables, I'd start at the lower end, say around 500W, and play with the numbers. (Prop size and clearance, RPM, weight, and so forth.
If low cost is a major consideration, 3C or 4C LIPOs, and 40 to 60A ESC's. An often ignored cost related issue has to do with the current draw of the servos
and any BEC built into the ESC. BEC's rated at 2A or so may be adequate for four to five servos, or not, depending on the exact servos used.
Worst case might be fast, narrow dead band digital servos, and certain models of a 2.4Ghz digital receiver.
I fly from a grass field, and prefer to have additional power available for that reason.
So the first question might be what prop size is appropriate for the model. Then what motor sizes produce enough power with that prop size.
Is that appropriate to the weight and wing loading?
Some of the "trainers" have very low wing loading (floaters) and others are intended for an introduction to such things as pattern models, or the more general
run of the mill models.
A low wing trainer I use is an Advance 25, with a Power 32 motor. It is intended for use with 500-800W motors, and I set mine up to behave much like a scale warbird.
(Higher than the usual wing loading, a bit "hot", and so forth.) With a 12x8x3 prop, and a 4C LIPO, it will cruse at 1/2 throttle, or hammer down, is fast, and has no problems with aerobatics.
Due to overall weight and wing loading, landing is also similar to that of a warbird. The same model can be flown with a much lighter, lower power powertrain, and due to reduced wing loading,
behave more like a "gentle" trainer.
Our club has members that prefer models that just float along, members that only like/fly scale models, members into high speed racing, and others in to 3D.
Up to 800W
From Power 32 data
Ideal for 30- to 36-size sport and scale airplanes weighing 3.5 to 6 pounds (1.6 to 2.7 kilograms), 25- to 36-size 3D airplanes up to 4.5 pounds (2-kilograms), or models requiring up to 800 watts of power.
From Power 25 data
Ideal for 25-size sport and scale airplanes weighing 3- to 5.5-pound (1.4- to 2.5-kilograms) 15-size 3D airplanes up to 3.5 pounds (1.6 kilograms), or models requiring up to 600 watts of power.
(My memory was placing the 32 at 600W)
Anyway, these are maximum watt ratings, not continuous.
I generally consider sport as the minimum level to have as a goal.
Besides sheer power, you also have to consider such things as wing loading as well as overall weight and the desired performance.
Even with a trainer, it's better to have at least a 1:1 power weight ratio. An argurment concerning this has existed
I prefer to set up for more power in order to allow for a short ground roll, rapid climb out, etc.
(Planes belong in the air, not trundling along in the grass!)
Electric Motors, when chosen properly, and with the correct prop can get (in theory) fairly high efficiency, say in the 80's.
There are some practical limits as well. Most ESC's are rated for 4C LIPO's. 6C rated ones are more expensive.
With all the variables, I'd start at the lower end, say around 500W, and play with the numbers. (Prop size and clearance, RPM, weight, and so forth.
If low cost is a major consideration, 3C or 4C LIPOs, and 40 to 60A ESC's. An often ignored cost related issue has to do with the current draw of the servos
and any BEC built into the ESC. BEC's rated at 2A or so may be adequate for four to five servos, or not, depending on the exact servos used.
Worst case might be fast, narrow dead band digital servos, and certain models of a 2.4Ghz digital receiver.
I fly from a grass field, and prefer to have additional power available for that reason.
So the first question might be what prop size is appropriate for the model. Then what motor sizes produce enough power with that prop size.
Is that appropriate to the weight and wing loading?
Some of the "trainers" have very low wing loading (floaters) and others are intended for an introduction to such things as pattern models, or the more general
run of the mill models.
A low wing trainer I use is an Advance 25, with a Power 32 motor. It is intended for use with 500-800W motors, and I set mine up to behave much like a scale warbird.
(Higher than the usual wing loading, a bit "hot", and so forth.) With a 12x8x3 prop, and a 4C LIPO, it will cruse at 1/2 throttle, or hammer down, is fast, and has no problems with aerobatics.
Due to overall weight and wing loading, landing is also similar to that of a warbird. The same model can be flown with a much lighter, lower power powertrain, and due to reduced wing loading,
behave more like a "gentle" trainer.
Our club has members that prefer models that just float along, members that only like/fly scale models, members into high speed racing, and others in to 3D.
