outrunner - inrunner etc.?!?!
 

i just got myself a troy built monte park flyer. i saw one of these things hangin on the prop and can't get my hands on one fast enough. anyways my questions are endless. can someone explain to me th difference between an outrunner motor and an inrunner? whats the deal with the li-po high discharge is what your lookin for batteries or something? also what is this Kv stuff? is it the higher the Kv the better? i was looking at one motor the himax 400 and it comes in the 720Kv and the 920Kv or something for the same price and it also comes in a like 4200Kv or someting. also between mounting these motors whats the options. i am just really lost being new to this park flying. looks really fun but i really need to understand it before i get flying! thanks

RE: outrunner - inrunner etc.?!?!
 

Look at hackers website:

http://www.hackerbrushless.com/motors_a20.shtml

they have a nice picture showing the outrunner and list some advantages. You will also notice in their specs that the higher kv engines spin smaller props.

RE: outrunner - inrunner etc.?!?!
 

Go to MotoCalc.com and download there 30 day deal. I just got back in this hobby and this program can help answer a lot of your motor-plane set up ?s. What I have learned is outrunners are the newest motor design and have more power then inrunners so they don't need high KVs (volts-RPM) like inrunners do. If I undrstand it correctly the lower the KVs the longer the flight times but may have a little less power then the same motor with a little higher KV rating(890-910) (flight time vs power and amp draw). Outrunners are good motors but I don't think there good for all set ups according to motocalc.

RE: outrunner - inrunner etc.?!?!
 

Bryan,

The basic difference between inrunner and outrunner is which part of the motor spins. Inrunner == inside spins. Outrunner == outside spins. Outrunners tend to have higher torque and can spin largish props without the need for a gearbox. Outrunners are much simpler to deal with, making them ideal for newbies to electric. Outrunners don't have gears to strip in a hard landing, making them ideal for newbie pilots. Inrunners tend to be capable of much higher RPMs, so they either spin a smallish prop really really fast, or require a gearbox to turn larger props. Inrunners are more complicated to deal with because of the extra calculation involved in the gearbox. Inrunners have the ultimate efficiency advantage.

Usually, outrunner motors are more than "good enough" for a given application. You don't always need the most efficient setup.

With LiPoly discharge rates, the higher the better. A LiPoly rated for higher discharge tends to give up its charge to the motor more efficiently, applying more power to the motor and/or running longer. Again, usually "good enough" is good enough. You don't necessarily need the best of the best available.

Kv is an RPM/Volt rating used on motors. There's nothing better or worse about a particular Kv. It's simply a description of how the motor behaves. Kv gives you a means to compare otherwise similar motors. The higher the Kv rating, the "hotter" the motor is. That is, the faster it turns on a given voltage. The lower the Kv, the more torque the motor has, and the larger the prop it can turn.

If this is your first plane, I suggest simply looking at what other people are using, and copy their setup. It's much easier to see how things work if you can play with it in your hands.

RE: outrunner - inrunner etc.?!?!
 

Thanks Matt, I now have a better understanding of KVs. The guy's at my local hobby store away's seem to shy away from answering these type of ?s.