Hi... Just starting out w/ my first trainer (TT Trainer 40), getting ready put it together this weekend and go flying. I've done A LOT of research on what are common mistakes, what to do and what not to do. The one thing that I'm not too sure on is Prop Balancing. I picked up a pair of 11x6 Top Flight Power Point props going on a 46fx. I just want to know what the best way to balance the prop is. I know you are supposed to spin the prop on the balancer, (which I am going to make myself) and it is supposed to stop in random places... my question is where and how do I remove excess weight from the prop without messing up the airfoil?? If someone would please describe the best way to do this it would be appreciated.

You'll probably get about as many different answers to this as you would if you'd asked how to run in an engine [img]i/expressions/face-icon-small-smile.gif[/img]

The first thing you should do before you even look at the balance is to lightly sand all edges of the prop including the tips to get rid of any mould flash. I hand start so I take particular care to round off the trailing edge more than usual where my finger will go. Then do an initial check for balance. If one blade is heavier then first sand off any paint such as brand names or tip paint. If it's still heavy then sand carefully and evenly all over the upper curved surface. There's no need to worry about altering the airfoil shape because you'll only be sanding off maybe a few thousandths of an inch and the props just aren't that accurately made, most of them have terrible airfoils anyway [img]i/expressions/face-icon-small-smile.gif[/img]

Chances are when you're finished the prop will always stop with the blades level and always the same orientation. This means that the prop hole isn't perfectly centred but for other than competition (extreme rev) engines this isn't a problem.

I sand the flashing off like downunder described, but to balance the prop, I add a little piece of aluminum duct tape on the light blade. The piece can be trimmed to size before pressing it down, then burnished to seal it down good. Place it on the rear of the blade near the tip. I've never had one lift or come loose and fuel won't penetrate the metal tape. Before balancing it's a good idea to paint the tips a contrasting color. This makes the propeller arc visible when the engine is running and may save a finger.

Molded propellers are pretty close to balance as manufactured. As matter of fact, a lot of fliers don't bother to balance the props and seem to do alright. It may effect engine life a bit but won't be any problem in operation. If in balancing the prop it takes a lot of sanding, or tape or whatever to get it in balance, you'd probably be better to discard it and get another prop.

This should stir up a lot of flak. There is an article out recently about not balbncing props at all. The ony part recomended is to put the heavier blade up when the engine is at TDC. I thought this was a bunch of hooey until I looked further into the argument. Single cylinder engines are impossible to balance internally. A counterweight on the shaft won't even do the job, although it does help some. The man who wrote the article is, and has been for sometime, profoundly deaf and tunes his engines by feeling the vibrations. His engines are some of the smoothest running at his field. Take it for what it's worth.

Sounds logical to me. I always thought it funny to balance a prop and then carve up the spinner to clear it.
later daveo