I have a scale LA5 (Brodak kit) that is powered with a Turnigy C3548-900. I am swinging an APC 11 X 5.5 EP prop at around 10,000 rpm.  The problem I have is that the scale of the aircraft requires a large spinner, 2 1/2 to 3".  None of the off of the shelf spinners seem to work.  The motor is mounted as an outrunner and vibrates big time at the higher rpm.  It is true that I am modifying the spinner opening for the pusher prop.  I have balance the prop and spinner - helped some but the problem still exists.  http://www.truturn.com/index.html   Has anyone tried a Tru Turn spinner.  They will custom cut for a pusher prop.  However a 2 1/2" black spinner with adaptor for my 6 x 1 mm prop shaft cost $70 + shipping.  Pricey but worth it if it works.  What say you all.  By the way the setup works well when using the spinner nut that came with the motor.

         

Keep in mind that E-flight makes spinners specifically for electric applications, built in collet, though with a rear mounted motor that wont likely help you

Hi John,
Okay, the motor is always an outrunner ... but you have it rear-mounted: right?
Even a tiny imbalance on the long overhang can cause problems.
It's not very likely, but a big spinner may cause problems, even if it is well balanced. See Igor's post in the "Start spin-up transition vibration" thread.

Dean P.

Correct - it is rear mounted.  Pushing on the prop revales a lot of flex in the motor shaft.  I have come to the conclusion that it's not likely a big spinner will ever work on this setup.  For the next contest I will just run the spinner nut.  After that I will flip the motor and rework the mounting system accordingly.  I knew better form the start but I figured it should be OK.  This is my first electric so there is a learning curve.

   Thanks for the input.

John,
I just read the post again, Look at the pic. I am currently running the new OS motor with a Tru-Turn 2.5 in spinner
mounted directly to a 6 mm prop shaft and it works fine with no vibration at 9600 rpm I have run similar Turingy motors in the past with the same spinner at 10000 rpm and never had vibration issues. The best way to figure that out is a test stand. If any thing goes wrong U can always push the panic button.  

Every time I've had a balance issue on the test stand most times the shaking have been severe and it could be a prop or spinner. Once I've solved the issue I never had a vibration on the airframe itself. But with that being said I did check
for vibration on a airplane just a few days ago. On the new OS motor I discovered the first time I was running a .250
bushing for a 6 mm prop shaft. Went flying any way there wasn't noticeable any vibration for that flying session. Next session trying the new APC props. I put the spinner on and wondered why the spinner wobbled. Since it was on the airplane any way. Translation too lazy to put it on the stand    I let her spin and sure enough there was some vibration. Shut er down and found out I needed a 6 mm bushing. So a quick trip to Tru-Turn ( I live just 3 miles from there!) produced a 6 mm bushing. And every thing has been just fine. Speaking of which I just got off the phone with Tru-Turn I'm going to pick up one of those newfangled fan cut spinners for one of the models I'm building for next years Nats. And by the way they way they can cut those back plates for pusher rotation as well.