stunthanger.com

Engine basics => Engine set up tips => Topic started by: Phil Goldberg on August 13, 2015, 02:28:45 PM

Title: Prop Balance
Post by: Phil Goldberg on August 13, 2015, 02:28:45 PM
Using a prop balancer I have gotten my props to stay put in any position, I assume this indicates a balanced prop.  I have had to add thick CA to the hub on a few that has quite a build up and takes the shape of the hub out of round.  Does this matter as long as the hub is in balance?  
Title: Re: Prop Balance
Post by: Howard Rush on August 13, 2015, 04:22:26 PM
It shouldn't matter.  A swipe of sandpaper on the end of the prop blade might be quicker.  A prop that shows significant imbalance when the blades are vertical is suspect. 
Title: Re: Prop Balance
Post by: bob whitney on August 14, 2015, 08:34:04 AM


 i think he is talking about when the blades are level and u flip it 180 degs and it flips back ,with my carbon props i sand off some of the heavy side of the hub ,rather than adding to the lite side .

being so close to the center ,it is hard to tell how much it will affect the running of the engine

after spending 30 min balancing a prop a greasy fingerprint will throw it out of balance so go figure

many a race has been won with a prop that was damaged half way through the flight ,and more than one speed event has been won with a prop that had the tips shortend with a pair of side cutters and rounded off on the pavement  .that said, the better the balance the better your engine will run in the long run.
Title: Re: Prop Balance
Post by: Bill Johnson on August 14, 2015, 09:43:16 AM
I balanced about 25 props 2 weeks ago. They were APC, Top Flight, Zinger and Master Airscrews. Various lengths and pitches. I always started sanding the face of the heavy blade, then the back until the finish was gone or the blade balanced. Very, very few were. Next sand the hub on the heavy side. Gave up on the sandpaper and switched to the Dremel with a fine sanding drum. A few more came into balance. Added one light coat of Aerogloss to the light blade. A couple more good. Finally, the puddle of CA on the light side of the hub. Maybe a little tweaking after that.

I've run 4 of the props with the lump of CA on them and absolutely no problems with vibration.

What was amazing was how far out so many props were.
Title: Re: Prop Balance
Post by: Jim Carter on August 14, 2015, 10:14:19 AM
 LL~ LL~  I jus' mount'em on a plane, crank up da' engine and hold it close to the cement til I git da' RPM I want!!  n~ Sho'nuff quick an easy!!  LL~ LL~
Title: Re: Prop Balance
Post by: Bootlegger on August 14, 2015, 01:32:11 PM

 Jim C, that is what we call "field" trimming here in Baton Rouge La. Per Big Ron here on the hanger... y1 y1 y1 :! :!
Title: Re: Prop Balance
Post by: bob whitney on August 17, 2015, 02:18:10 PM


with my carbon props i check the balance then take the lite blade and finish it to 320 paper , then bring the heavy blade to match . if i do the heavy blade first i then need to match again
Title: Re: Prop Balance
Post by: Phil Goldberg on August 17, 2015, 04:42:50 PM
I seem to have had some success balancing the hub by taking equal amounts of material off from each blade that are on the heavy hub side. This is after balancing the blades.  Is this a good alternative to adding unsightly CA to the hub. This way the hub stays in round.