Prop Motor/ESG/Battery combo for a Masala Sailplane

grampayeehaa

grampayeehaa

Member
As you know from my last post, I wish to put together a Masala E powered Sailplane from Nitroplanes. I am now working on the power train for the bird. I took the general information supplied by Nitroplanes, (motor,esc and battery), to work out the combination, (870kv motor, 60amp esc and an 11.1 v 3800-4000maH battery). I am concidering a Big Foot 25, 870kv, 550watt motor, a Dynam 60a esc with a 3a bec and a a Sky Lipo 11.1v, 4000maH 20C battery.

I used Toni's formulas he posted on YouTube to make my calculations. I took the watts of the motor,(550) divided by the voltage of the battery, (11.1) to get the amp usage to the motor, (49.5). Watts/volts=amps. That told me that, by applying Toni's suggestion of using an ESC 10-20% larger than required, I needed a 55-60amp esc. Next came the battery. By using Toni's formula, mah*C/1000=amps 4000*20/1000=80. That gave me a continuous draw capacity of 80amps. More than enough for my requirements. Are my calculation sound?

Next question. I don't understand what the "can" dimensions have to do with the motor. The Big Foot 25 has the suggested shaft size and "can" diameter. It is only a couple of millimeters short in length.

I would like to thank Toni. I have learned a lot from his tutorials.
 
Tony

Tony

Staff member
Your calculations are perfect, and that setup, with the proper prop, should prove to be great.

And the can size lets you know what the actual outside size of the motor is going to be. Some of the tight fitting spaces in some of these planes are hard to find motors for. A lot of times, you will see things like 2215-1300. What that means is the ARMATURE size is 22mm x 15mm. IT's quite confusing and I wish everyone would just stick to a standard of measurement.
 
Tony

Tony

Staff member
Don't get me wrong, it's a great name! And if you want to make it rhyme, "there is no "i" for a guy" lmao. Sorry, had to do it.
 
grampayeehaa

grampayeehaa

Member
As best as I can figure, the plane uses a 13X6 or 14X8 folding prop. Because I am a little fuzzy, more like a lot fuzzy, about props and what diameter and pitch does, what can I expect/difference between the 2 props?
 
Tony

Tony

Staff member
The 14x8 will pull quite a few more amps from the battery. One thing to remember though is that the plane is a sail plane so you won't use the motor except to climb. I think you will be fine with the 13x6. I'm running a 13x8 on my Edge with a 32 size motor, and the suggested prop for that is a 12x6. 14x8 is a LOT of prop.

The first number is the overall length of the prop from tip to tip. The second number is how far it will go through the air, or how far it will push the air in inches per one revolution. If you were to put this in jello, where there is force applied per revolution, one turn of the first prop would move forward 6". The second prop would move forward 8". Hope this makes sense.
 
grampayeehaa

grampayeehaa

Member
That does make it a little clearer. I am sure you are right about going with the 13X6. This whole prop size thing is still a bit confusing. My Radian uses a 9.75X7.5 prop and it rockets into the air like its being chased by savages. Radian is half the size, both in weight and overall size than the Masala. My 6' Telemaster is using an OS46 glow motor with a manufacturer's suggested prop size of a 10X7 to a 12X?. I split the difference an went with an 11X7. The Tele seemed sluggish and labored so I dropped to a 10X7 and she perked right up. While the Tele is no speed demon it can move around at a fair clip. I was thinking that it might be a good idea to pick up a few other/smaller props at $5.00 each and see which one does the better job.

Thank you Tony. Hey I spelled it with a "Y" this time.
 
Tony

Tony

Staff member
Your phone typing makes no sense lmao. It's that tiny little iphone that's the issue. Get an android! lmao
 
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