colmo-RCU

Please, somebody explain to me the numbers on the rimfire motors, and all brushless in general. How to match motors and planes, and also how to know what prop and reduction gear to use.


SOS

Thanks, Colmo

coolbean

Check this out.
[link=http://www.rcuniverse.com/forum/m_4176153/tm.htm]http://www.rcuniverse.com/forum/m_4176153/tm.htm[/link]

Matt Kirsch

My Feedback: (21)

Colmo,

Right off the bat, it's crucial to understand that you're not going to become self-sufficient in designing electric power systems overnight. There's quite a learning curve to it, and the best way to start out is to pick a plane you like, then copy what someone else has done to a similar plane. In fact, you can power practically any airplane nowadays without having to crunch a single number.

Secondly, the "numbers" are meaningless with regards to determining whether a motor is suitable for a particular application or airplane. Every manufacturer has a different numbering scheme. Some use the dimensions of the outside of the motor. Some use the inside dimensions of the motor. Some use completely arbitrary numbers. In any case, they do not give you any indication of the capabilities of the motor. They're arbitrary model numbers, much like the model names used on cars. Think about it this way: Would you know if a Toyota Corolla was a heavy-duty pickup truck or a compact car by simply looking at the words "Toyota Corolla?" You wouldn't be able to tell without looking at the specifications, and that's how it works here.

The key to electric is in asking the right question. Most people come to electrics with a "glow engine" mentality, asking, "What motor goes with what plane?" or something similar. The correct question to ask is, "How much power do I need?" Figure out how much power you need, then design a power system that can provide that power.

colmo-RCU

Thanks a lot, Ill just start trying. Actually I designed a small pattern plane that I think would fly well with a Norvel 061, and I installed an AMMO 3600 with a 910 mAH lipo and 5:1 gear with a 8/6 prop. It is greatly overpowered, which I actually like. Now Im thinking of using 2 of these systems to power a twin engine super sportster 40, which was supposed to use 2 .25s. What do you think? We`ll see if it moves.

Anyway, thanks a lot,

Mariano

exeter_acres

My Feedback: (2)

See...you are still thinking like a glow builder...
You can't do that!


When I set up a system... the first thing I figure out is how heavy will the plane be when it is ready to fly (AUW)...
then I think about what kind of plane it is and what style of flying.....
then I think about the power ratio in relation to watt output of the system....

50 to 75 watts per pound for scale
100 to 125 watts per pound for sport
150 and more watts per pound for 3D and unlimited vertical

just general guidlines, but will work well...
and then piece together a system

One way I think about it... that little chunk of metal that spins the prop isn't the motor... it just uses the watts it can get..
The BATTERY is the key... if you set up an amazing motor/esc combo, but don't give it the watts it needs, it won't work....
so you have to think about the output capabilities of the battery....and go from there...


I hope that helps a bit...