25mm for slightly more power

[swatson144]

Well I upped the test on my 25mm frankenmotor into the database. Also put a pic of it in my album along with the plane I am going to use it on.

The gbv single (installed on it) is giving very little thrust over it's 7.0 once AUW, but at 3.8 A it gives good flight on a 720mAH 2s1p lipo. Which begets the problem of hotter motor draws much more current than I want WOT.

I figured if I build a 25mm motor I'd get a nearly free 9% increase over the installed 22.7. Or could it be that simple?

Testing showed that the 8x4 gws (same prop I was using on the 22.7)gave me 8oz at 3.83 A. I still need to test the single and see what I get out of it. Probably anecdotal at this stage I just thought it was interesting. I perceive the 9% increase in stator size appears to have given me a smidgen less than 9% increase in thrust. which should make a world of difference in this plane. Waiting for another calm day to try it.

As soon as my raw materials arrive I'll build a leaner/lighter version of the same frankenmotor. Well I guess I might as well test the single gbv now as the only props I have left are the smaller ones suitable to singles after fridays windy flights. i still have a 10 pole I need to test also.

[LBMiller5]

I think that you would get more than a 9% increase. The power out in a motor equals the torque times the RPM. Torque = force x moment arm. Going from a 22.7mm Stator to a 25mm stator gives a change of (25-22.7)/22.7. This is 2.3/22.7 = 10.1%.

I believe you calculated the formula by taking (25-22.7)/25 which equals 9.2%. I know it is not much, but every bit counts!

Lucien

[swatson144]

Yep you caught me out :oops: . That at least partly explains why I got so close to 9% more power despite a larger airgap in the 25.

[DadHav]

Hi Swat, Did you build using a 9 or 12 leg stator. I finished a 12 leg single and really got a lot more power than the 9 leg, not to mention a much more power than the 22.7 single. I don't have my notes in front of me, but my guess is you will be really happy with the way the motor works when you cut down the air gap. I'm using .005 in American thousands. Good running but you really can't get any kind of debris in there.
I'm not sure how to add test results into this data base, but maybe I should take some time to figure it out.
Oh, by the way I finished my first motor with the steel tube stock for the flux ring. I owe ya pal. I'll put some pictures in my gallary, but there's a few on the string about the stator edges. Below is the 25 mm single that I just finished last week. She really runs good. So far I have been matching the AXI motors that I have and replacing them with the hand made ones. The others are on E-Bay right know. I'll use the money to make more better ones. Sorry I mean gooder.
Thanks again.
John

[swatson144]

It was a 9 arm 3 stacker. I had to turn the stators down to get an air gap. I'm workin up the nerve to wrap a 12 arm 5 stack, I have finished except wraping and finish reaming the shaft hole. I fly mostly over a dirt lot and I keep the gap .006 - .01" 006 if I launch em and catch them. .01 If they have landing gear, If I know it's gonna be a victum of serial crashing I'll even go .015, Like on the planes I let others fly to get em hooked :twisted: . Hey the more people buying this stuff the cheaper it gets. I'm waiting on the nail polish to dry on my 25mm 12arm x 10mm I broke the sharp edges with a diamond christmas tree bit and wrapped it in un waxed dental floss, then coat it with 3 coats of "hard as nails" clear nail polish. Glad I could help with the source for the metal. After I chucked up my 1st piece of 4130, and started cutting, I was grinning so hard my ears hurt! For the data base PM JayC and tell him you can and will give Volts amps thrust and rpm, include your email address and I bet he'll send a login. I just opened a new motor and wrote the blanks down in order to facilitate testing and closed the window without saving. Testing is a chore and takes almost as long to do as makin them. I need to get in the habit of setting up the gear and do some machining while I top off the battery. then test a prop and machine while topoff etc. Unfortunately You can't really enter none standard stators and cans. I seem to remeber JC mentioning doing some changes, maybe soon since he's finished with the motorcalc and his kid is old enough to feed himself :wink: and he of course has nothing else to do :twisted: Or maybe just post them with proper notes in the remarks?

[DadHav]

Yep, I understand. The triple 25-12 that I made was GB stators and magnets. I would imagine it not making a difference that I did the beauty pagent thing with the outside, I did just remember that on the single LRK above I used N50 5x5x1.5 magnets. I thought for a single, being in-between the 1mm and 2mm thickness might work well. I wonder how much better it would run with the 2mm magnets? Thanks for the suggestion about Jay. I've e-mailed him a couple of times with regard to testing 25-12 stator motors. I'll try to get caught up on things and get back with him.
John