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dk prop balancer


jock
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Made the prop balancer 2day.waiting for glue to set in the dowels i will balance them of the hub and then see what they r like on the hub,first time ive tried this.when i took the prop off one of the holes was enlarged by a few mill due to prop strike.ive plug it..

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573363f3b6239_GTi201(Small).jpg.6741b0a9

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Colin, it doesn't quite work like that. If you took a perfectly balanced 2 blade carbon prop apart and then taped a coin to one tip and then an identical coin to the other blades root they would both weigh the same on the scales but would each have completely different rotational inertia and therefore would be completely unbalanced when in use.

It is actually possible to have a single blade prop so long as it has a suitable counterweight on the opposite side. Because of the short moment arm of the weight it will be much heavier than the blade however the prop will be 'balanced'.

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Hi Jock,

Why not weigh each blade on a set of digital kitchen scales, Then add paint or lacquer on the two lightest blades to match :D

Colin B

HI i saw some info on what u said.but this looks ok i hope.. use the tip of a table with a thin alloy sheet put the heavy prop on first and find the pivot point mark it then do the same with the other 2, mark them then tape/paint to macth the heavy prop and hopefully iam there, the small piece of wood is the sliding weight to move along the board to find the pivot point then mark.i shall see if its as easy as ive said.if it aint i will have a good bone shaker....

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Colin, it doesn't quite work like that. If you took a perfectly balanced 2 blade carbon prop apart and then taped a coin to one tip and then an identical coin to the other blades root they would both weigh the same on the scales but would each have completely different rotational inertia and therefore would be completely unbalanced when in use.

It is actually possible to have a single blade prop so long as it has a suitable counterweight on the opposite side. Because of the short moment arm of the weight it will be much heavier than the blade however the prop will be 'balanced'.

The paint / laquer idea works 'well' I have used it many mny times as a method. The reson it works is becsue of the 'spread' of weight over the entire blade and not one point.

SW :D

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Hi simon yes paint and varnish i shall try that on the doodlebug prop,well ive just fired the gx up to see if i did ok on my first prop balance,and ive gone from bone-shaker to smoothie its great,im sure its chucking out more thurst the more i run the engine in,,just need my harness back and im ready to roll..paul bailey is taking an intrest in us gx nutters.is there a bailey gx on the drawing board.paramotorbart is putting one in a bailey frame,it looks brill.he is making his own pulleys etc,will be one to wacth...

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The paint / laquer idea works 'well' I have used it many mny times as a method. The reson it works is becsue of the 'spread' of weight over the entire blade and not one point.

SW :D

Never said paint and lacquer doesn't work. What doesn't work is thinking that if 2 blades weigh the same when weighed on scales they will balance when rotated. Consider swinging a 1kg weight round your head on a negligible weight piece of 1m string. Now oppose that with another 1kg weight on the opposite side on a 10m negligible piece of string. Both sides would weigh the same on a set of scales but they wouldn't they be balanced in rotation.

Use paint/lacquer for fine tuning the balance but verify the balance by use of a pivot at the prop center. Even then this is only a crude form of balancing with limitations. Improperly balanced props ruin perfectly good engines.

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