CDrom motors again!

[bigandy]

Morning all,

I'm just about to embark on a mission to replace a speed 400 (6v) with a CDrom motor. I've nearly finished milling the motor at work (on the NC mill, woohoo!), and I now need to try and get the winding/magnets right to get a similar (if not slightly better) performance than a standard speed 400. IDeally, I would like to have the same power, for less weight and more efficiency.

Has anyone got any suggestions for windings/magnet layouts that will get me close?

It's for a delta wing by the way, either 7 or 8 cell nimhs, turning a Gunther spoon prop (5.5x4.3"?)

Cheers folks

Andy

[rdn1153]

...and you're only machining one???? hmmmmm???? What about your friends in California /ubbthreads/images/graemlins/tongue.gif

Nonetheless, I'll be watching this thread, I'm enjoying the learning curve. I'm thinking something along this line would work in my old gas, Cox, 1/2A racer. Hate to get rid of the old toys, just can't seem to let go of them, I'd rather crash than trash /ubbthreads/images/graemlins/cool.gif

...Rick

[bigandy]

Well I've got 6 cans machined, just waiting to parted off the bar stock they are attached to! (3 bars, one on each end!)

I might see about getting some made up in the future! Or I can supply the 3D cad file to anyone that wants it (Solidworks, or naything that Solidworks can export!)

Cheers
Andy

[Captain_Bodge]

Well, the C&K I use on my gryphon wing drives a Gunther prop at around 9A full throttle (on 2 liths) and gives ballistic performance. It's probably similar in power to a sp400, but at a great deal less weight. It's 9 turns, of whatever is the thickest wire you can use to get 9 turns, and stock C&K magnets (N48 I think).

[dongle]

second bodge there - my 10 turn home made was extremely powerful and due to the reduced weight the plane flew a lot better - I'd say it was a close match. If you are looking for something with a little more torque you could consider a double stator - weight wise it will go up to the mid to high 40 g's, so still only about 2/3rd the weight of a 400 but the available wind choices and hence current range are greatly increase for the power bands you'll be looking at.

[bigandy]

So 10 turns is about the wind to go for then. Good stuff. How does something like a 15 turn motor comapre to that then? Would the performance drop off considerably (or the current draw drop off considerably)?

One of the days I'll get round to trying out a double stator motor. I'm trying to get a list of single stator winds that are good for certain applications still though. My cut down gryphon is also ballistic on a C&K 7 turn motor with a 3*3 prop. It's not the most efficient though!


Cheers
Andy

[dongle]

Quite a large difference between a 15 turn and a 10 turn, it's going to pull considerably more amps on 10, but will also produce more power. The question I would be asking is just how much power does this aircraft sap from the speed 400 to fly well? If you are only looking at about 80 watts then you are going to be OK with a single, but if the prop is quite harsh on the motor and you are pulling nearer the max (about 160watts)to get decent performance then really a double is going to be the only sure-fire way - otherwise you'll end up with a melted single stator /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/grin.gif