How do you know what brushless motor to use?
08-11-2007, 10:53 AM
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How do you know what brushless motor to use?
Hi-
I'm not familiar with an easy way to determine how to pick a brushless motor for a plane. In the past ,I've always just looked for the plane's weigth recommendations for a motor but not all websites give you that. I like the E-flite series that names their brushless motors to the power of a glow engine... .25 or .40 and so on.
Is there a rule of thumb or something you can rely on to pick the right motor size?
Boot
I'm not familiar with an easy way to determine how to pick a brushless motor for a plane. In the past ,I've always just looked for the plane's weigth recommendations for a motor but not all websites give you that. I like the E-flite series that names their brushless motors to the power of a glow engine... .25 or .40 and so on.
Is there a rule of thumb or something you can rely on to pick the right motor size?
Boot
08-11-2007, 01:26 PM
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RE: How do you know what brushless motor to use?
If you don't get the answer you are looking for here, try emailing Jeff at Heads Up RC. He's great to work with and is loaded with information. His email address is [email protected] Just tell him what you have and he'll recommend something. Then you can take it from there.
Take a look at some of his products, too. http://stores.ebay.com/Heads-Up-RC
Take a look at some of his products, too. http://stores.ebay.com/Heads-Up-RC
08-11-2007, 05:21 PM
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RE: How do you know what brushless motor to use?
Bootstrap,
The watts per pound method is the only one I know. With a rough figure for the all up weight you then compare it against a table that looks something like:
50-70 Watts per 450g - Minimum for reasonable performance flight. Slow flyers and slow park flyers
70-90 Watts per 450g - Slow flying scale models, Trainers.
90-120 Watts per 450g - Sports aerobatic. Fast scale models.
120-150 Watts per 450g - Advanced aerobats. High Speed Models. Excellent Vertical performance
150+ Watts - Very High Speed, Unlimited Vertical Performance.
NB - 450grams = pound.
However, when picking a motor you need to also choose the correct engine speed (rpmv or sometimes kv) - this is harder as you need to know what voltage you plan to run on the plane 2s/3/4s for parkfliers, 4s/5s/6s (and beyond) for glow conversions etc as well as taking into account what sort of prop you need to run (wide slow flyer prop with lots of thrust for 3d, or small prop with lots of pitch speed for speed, and everything in between).
I know it can seem daunting at first. I guess the thing to keep in mind is that the reason it seems daunting is because of the number of options. This gives you a lot more flexibility in tailoring the power system for your electric aircraft. You might find these notes useful if you are new to electric aircraft:
http://www.oz********.com/2007/01/el...ic-flight.html
unitedhobbies.com also list some much cheaper (and not as good a quality, but much cheaper) outrunners with a "this would replace a .40 glow engine type ratings".
HTH.
Cheers,
Oz.
The watts per pound method is the only one I know. With a rough figure for the all up weight you then compare it against a table that looks something like:
50-70 Watts per 450g - Minimum for reasonable performance flight. Slow flyers and slow park flyers
70-90 Watts per 450g - Slow flying scale models, Trainers.
90-120 Watts per 450g - Sports aerobatic. Fast scale models.
120-150 Watts per 450g - Advanced aerobats. High Speed Models. Excellent Vertical performance
150+ Watts - Very High Speed, Unlimited Vertical Performance.
NB - 450grams = pound.
However, when picking a motor you need to also choose the correct engine speed (rpmv or sometimes kv) - this is harder as you need to know what voltage you plan to run on the plane 2s/3/4s for parkfliers, 4s/5s/6s (and beyond) for glow conversions etc as well as taking into account what sort of prop you need to run (wide slow flyer prop with lots of thrust for 3d, or small prop with lots of pitch speed for speed, and everything in between).
I know it can seem daunting at first. I guess the thing to keep in mind is that the reason it seems daunting is because of the number of options. This gives you a lot more flexibility in tailoring the power system for your electric aircraft. You might find these notes useful if you are new to electric aircraft:
http://www.oz********.com/2007/01/el...ic-flight.html
unitedhobbies.com also list some much cheaper (and not as good a quality, but much cheaper) outrunners with a "this would replace a .40 glow engine type ratings".
HTH.
Cheers,
Oz.
