Balancing a spinner trick
 

I've got the basics under control ;)

However, I was looking at some vids where the counter balance weight is NOT applied directly to the light side of the spinner. Rather at 2 places " eleven & two o'clock" of the spot (in smaller weights) Why?

Is that the way to do it for fast RPMs?

RE: Balancing a spinner trick
 

Why would you add weight to balance a spinner? I remove from the heavy side with a Dremell. First balance the back plate alone. Make an index mark on it and put the cone on the backplate and balance the cone back to neutral.

RE: Balancing a spinner trick
 

Big difference in static balance (which is worthless) and dynamic balance (which is not a trivial effort). So I just use Tru-turn and don't worry about the spinner.

RE: Balancing a spinner trick
 

A few years back World Models was selling a highly polished spinner for the 46 size P-51, it came in a paper box. The same spinner also came with the Voodoo and Dago Red Mustangs for a while.
All of those we saw were badly out of balance, both back plate and cone. We could balance static, but still it shook like hell. You can't go wrong with Dave Brown or Tru-Turn for metal spinners! Du-Bro is not bad for plastic.

RE: Balancing a spinner trick
 

That's kind of my thought as well.... When you balance a prop you don't add weight, why would you add to a spinner?

RE: Balancing a spinner trick
 

Personally, I don't see any problem adding small weights instead of grinding. More control I guess. Plus if it doesn't work out the first time due to static balancing being not perfect, you can undo.

I always balance the backplate first (there i use a large drill to grind some material in the desired spot).
Then, I ad weight little by little in the middle of the spinner (not at the extremities) to minimize the "counter balance" at the wrong end problem.

I was just asking about the theory of adding weight a 11 & 2 o'clock. anyone knows?

RE: Balancing a spinner trick
 

I know there are those that do this when balancing a tire on a dynamic (spin) balancer.. This is usually because they missed the spot the machine told them to put the weight and the second weight is countering the initial mistake.. The solution is to move the first weight not add a second one.. Rule number 1 (well maybe not first but right up there) is that rotating weight robs horsepower..

RE: Balancing a spinner trick
 

Nelson mills out some material in the backplate. He mills a rut 2/3rds of the full circle. The heavy part of the backplate is opposite the piston.
The cone of the spinner is a machined part and only a doofus would think that it needs balancing.

RE: Balancing a spinner trick
 

At TDC ? Same side as crank weight?

RE: Balancing a spinner trick
 

FF...yessir, he's got the heavy part of the back plate in phase with the counterweight.

I don't always get the back plate indexed perfectly after a prop change and it doesn't make that much difference...not with these 6 7/8 inch diameter props.

RE: Balancing a spinner trick
 

Hell, you can break off half a blade of the prop and it will run fine as long as the blade that remains is lined up with the counter balance.

RE: Balancing a spinner trick
 

I had that happen inflight with a hand carved pusher prop on a Cox TD and it made the model seem faster. I ran it that way until the other blade broke off.

RE: Balancing a spinner trick
 

I blew off half of a blade on an ST X-40 powered F1 at a race. Engine picked up just over 1,000 rpm on the tach and plane went 4 seconds faster than it's previous best time. Vibration level was about the same.

RE: Balancing a spinner trick
 

On a Diamond Dust with a YS 45, I threw one blade at the hub on a 9X9. I tell you, that was about the loudest sound coming from the sky I ever heard. I killed the engine immediately and landed. The only thing was the engine was loose. Just tell me how violent it was to back off four nylock nuts that far!

With a DF powered Dust, I was testing grey pylon props. Every one I tested lost 3/8" off the tips of both blades at the same instant, usually during an abrupt turn. It didn't seem out of balance, It just wound up higher and dropped air speed.

RE: Balancing a spinner trick
 

On the X-40 we used rather small light wood props, about 8 1/4" diameter. Plastic props most likely weight too much.

RE: Balancing a spinner trick
 

And you didn't loose a whole blade:)

RE: Balancing a spinner trick
 

No, it split on a diagonal line following the wood grain. It was full blade width at the hub, down to a point at the tip with the back half gone. I can't say what the long term effects on the engine bearings would have been, but it didn't seem to bother them after a two minute run on the ground and in the air. I might have pursued the method a bit more for racing, but a buddy that knew of it decided that it might not be the best technology to allow into racing, so a ban was put into effect the next rule cycle. Now (since about 1998) pylon rules state that the prop must have two blades of equal size and shape.

RE: Balancing a spinner trick
 

Ya know, as I get older, I have learned to keep a lot of things to myself[sm=47_47.gif]........Also how to plant a seed and watch rumor run rampant to my designs. [sm=stupid.gif]