Prop balancing

rv72004 · #1 04-11-2006, 12:35 AM

I am considering removing the outer rivets from the doubler plate of the spinner backplate and substituting with 6/32 screws and nuts. This will enable me to balance the hartsell constant speed prop . ie it will enable a place to add weights for balancing.
What have others done?

jonbakerok · #2 04-11-2006, 06:01 AM

Quote:

Originally Posted by rv72004

I am considering removing the outer rivets from the doubler plate of the spinner backplate and substituting with 6/32 screws and nuts. This will enable me to balance the hartsell constant speed prop . ie it will enable a place to add weights for balancing.
What have others done?

Personally, I wouldn't go to that much trouble. It usually doesn't take that much weight. All I had to do when we balanced mine was to replace one of the spinner mounting screws with a longer screw and a thick washer.

dan · #3 04-11-2006, 07:50 AM

Don't know about your hub, but my C2YK hub has no fewer than 6 built-in provisions for adding weight -- two at each blade root and one on each side of the rear of the hub (maybe more if I missed 'em). When I had my prop balanced, it was an 8 gram weight that needed to be added. We're talking miniscule. Take a look at your prop hub and you'll probably see the "built-in" locations I'm talkin' about.

AlexPeterson · #4 04-11-2006, 08:52 PM

The guy who dynamically balances props around here (http://www.propbalancing.com/) puts the weights, which are small AN3 bolts, in the holes on the ring gear. What else would those holes be for?

dan · #5 04-11-2006, 09:05 PM

Quote:

Originally Posted by AlexPeterson

What else would those holes be for?

Harmonic dampener? Just a guess. I'll ask the guy I know from SoCal who recently installed one how he mounted it...

sprucemoose · #6 04-11-2006, 09:17 PM

Harmonic dampeners (at least the Landoll) are mounted using these holes, but I don't know if that was the intended purpose for them.

13brv3 · #7 04-11-2006, 10:48 PM

Quote:

Originally Posted by AlexPeterson

The guy who dynamically balances props around here (http://www.propbalancing.com/) puts the weights, which are small AN3 bolts, in the holes on the ring gear. What else would those holes be for?

I've seen this done, and have done it myself as well. It sure seems to work well, and it's convenient as can be.

Cheers,
Rusty

osxuser · #8 04-11-2006, 11:54 PM

They holes are actually to mount a spinner bulkhead on, see also Mooney M20J spinner installation. (You should know that one Dan

).

dan · #9 04-12-2006, 12:10 AM

Quote:

Originally Posted by osxuser

They holes are actually to mount a spinner bulkhead on, see also Mooney M20J spinner installation. (You should know that one Dan

).

I was oblivious when I had my Mooney...I'm probably still oblivious.

Bryan Wood · #10 05-03-2006, 11:22 PM

Today I was driving into the airport on my way to convert avgas into noise and saw a Lancair getting a dynamic balance out on the ramp. Wanting to have this done on my airplane for some time now I stopped and asked when he could fit me into his schedule. What a nice surprise to be told that he could fit me in within the hour.

The change in the airplane cannot be overstated. From idle as the power is applied the engine is silky smooth. After settling up with this gent he turned me loose to have a flight and try out the new feel of my baby. Prior to the balance there was a feeling of power when the throttle was push in on the runway as the plane surged forward and the acceleration sits me back into the seat. There was a particular point in the take off roll where the prop felt like it was cavatating for lack of a better description and then it pulled hard again, or at least the sound gave this appearence. When flying the factory 9A with the MT I didn't notice anything like this and just thought that it was a characteristic of the Hartzell. Now as the throttle is advanced the engine feels smooth and the pull sounds and feels steady. If the truth be told the plane feels less powerful with the new smooth feel. On climb the same could be said. The cruise climb was good at around 1100fpm and 130mph indicated and the tower gave a frequency change at mid field on downwind, but the plane just felt less powerful. After leveling off and setting up for cruise I was beginning to like this smoothness as I got used to it, a lot. The feel on the rudder pedals was different and placing my hand on the glare shield showed the vibration that I never truly realized that my plane had was gone. On decent I've had a vibration that shows up as the manifold pressure is reduced below 20 inches or so with the prop set at 2300 or above. I've just been compensating for this by slowing down the prop on decent to 2200 and as this became habit I kind of stopped thinking about it anymore. This was a subject that I talked about to several people running my engine prop combo and almost everybody had the same vibration which made me think it was normal. Well this is gone now too. At this time I'm thrilled with the improvement and embarrassed that it took me almost two years to have the prop balanced. If your wondering about having yours done the results have the potential to be a big improvement. I haven't read the print outs yet, but we started at .19 and ended up at .031 after the balance. With no experience with this it is unkown to me if this is a miracle case or if gains such as this are common. It is also unknown to me how bad .19 actually was. All I know is this was money well spent.

Blue Skies,