PROP Balancing

[t michael jennings]

Gentlemen,

Last week I purchased a wood Master Airscrew 10X6 prop from the LHS.

Checked out the balance.  One end fell like a lead weight.  This is the most out of balance that has ever crossed my bench.

Where on the prop is the safest place on the prop to remove the excess wood, such as the leading edge, trailing edge, or tip?

Thanks for your answers.

T Michael Jennings         
Knoxville, TN.

[david beazley]

I am sure others will chime in on this, but I have always removed material from the face of the heavy blade.  Taking it off the rearcan change the pitch.  Taking off the LE or TE can change the width and create other issues.  Instead of removing material from heavy blades I tend to add weight to the light one.  You can use paint, dope, or just add CA to the light side and smooth out with a finger inside a baggie or use rubber gloves.

[Douglas Ames]

If it's that bad I'd mic the blade thickness near the tip.
Check for symmetry in the way the blades were carved/sanded.
Are the blade lengths equal? (hole centered)

[Keith Miller]

I gradually sand material off the rear face of the heavy blade starting at the tip (greatest moment).  Usually the rear face is already flat, so some material removed won't change pitch. 
For ugly cases, I agree with David - add some weight to the light side.

[Hoss Cain]

Gentlemen,

Last week I purchased a wood Master Airscrew 10X6 prop from the LHS.

Checked out the balance.  One end fell like a lead weight.  This is the most out of balance that has ever crossed my bench.

Where on the prop is the safest place on the prop to remove the excess wood, such as the leading edge, trailing edge, or tip?

Thanks for your answers.

T Michael Jennings         
Knoxville, TN.

Mr. Jennings:

   Yes there are as many thoughts to this question as there are props. HA!  As one when very young and had to even carve some props without much to go on, I did get some flying in.
I have a few points to make here. First, when I was an airline pilot and when we did not have so much "security" to worry about and the fact that I did a lot of pylon racing back then, I spent many an hour in a hotel room with some wood props, sanding blocks and other small tools.
One of the most disappointing things was when I spent hours and would have  2 props all the same measurements and the same weights, etc.
Well you guessed it, one would really move the machine through the air and the other might be just absolutely garbage.   
   Still I can give a few items that one can look for.
1. The old thing that "never take from the bottom..."  POOF, worthless!  Today's wood props have a lot of paint. I find taking down the back side starting at the tip and with good hand (block or flat blade) sanding and checking can be an easy place to remove paint weight.
 2. Taking off thick paint (paint meaning varnish of whatever kind) with sanding lightly and long is a good method, on any side.
3. Keep balancing as you work. Another good spot is to take off the razor trailing edges. Use of 1/64th to 1/32nd of the trailing edge is fairly good. Don't overdo it. However it can help when finger starting (The right way for a real CL flier. Right? 
4. If your prop/s have a squared off tip, you can get a lot of weight off by a nice sweeping oval of the front edge. Be sure to not change the last 1-3" OF THAT OVAL too much but have it more to the last 15% of the blade length. Don't get too slender.
Balance, balance, balance, as you work. You don't want to overkill so take it easy, and work gently.

IMO square blade tips are not much for good flying.  L.E. Tapered are best and especially the last 15% of the blade length.
You can get some better blades if you take your time and try different shapes. Kind of fun but at times  very much LESS than fun!   
Good Carving and sanding!!

[Steve Helmick]

To avoid this situation, I'd suggest one of the little fingertip balancing gizmos. Several companies make them. Take it into the shop and pick the prop with the best balance! You might want to engrave your name on the outer face of the cones, in case somebody accuses you of lifting the balancer. Tower is supposed to have this one from Thunder Tiger...and the LHS is not likely to carry them, so it's yours by default.  Steve

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXBFRT&P=7

[Motorman]

The face is the flat side, the back is the hump side.

I guess taking it back is not an option? I would determine why it's out of balance first. Is one blade thicker, is the hole drilled off center, is the wood radically different, is your balancer ok? If it's that bad just cut your losses.

MM

[Brett Buck]

Gentlemen,

Last week I purchased a wood Master Airscrew 10X6 prop from the LHS.

Checked out the balance.  One end fell like a lead weight.  This is the most out of balance that has ever crossed my bench.

Where on the prop is the safest place on the prop to remove the excess wood, such as the leading edge, trailing edge, or tip?

   Reduce the thickness instead of the blade area or diameter.

     Brett

[Avaiojet]

Gentlemen,

Last week I purchased a wood Master Airscrew 10X6 prop from the LHS.

Checked out the balance.  One end fell like a lead weight.  This is the most out of balance that has ever crossed my bench.

Where on the prop is the safest place on the prop to remove the excess wood, such as the leading edge, trailing edge, or tip?

Thanks for your answers.

T Michael Jennings         
Knoxville, TN.

I purchased this gizmo thingamabob many eons ago. Used it plenty of times. The prop balancing shaft actually sits on double wheels. Really sensitive, works great. Not sure if it's still produced?

Took it out of moth balls just for the shoot. Here's my spread, like ebay.

Bob Hunt packing foam? 

Gotcha Bob!   

[John Rist]

To avoid this situation, I'd suggest one of the little fingertip balancing gizmos. Several companies make them. Take it into the shop and pick the prop with the best balance! You might want to engrave your name on the outer face of the cones, in case somebody accuses you of lifting the balancer. Tower is supposed to have this one from Thunder Tiger...and the LHS is not likely to carry them, so it's yours by default.  Steve

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXBFRT&P=7

Not possible. LHS have stickers all over a prop.  e-props come in a sealed plastic sleeve.