splais

My Feedback: (25)

I purchased the Dubro balancer and am very happy with it. The price is right and it is easy to use. But I'm having a problem I never got an answer too last time I got into this balancing thing. I'm getting conflicting information on where to sand. The only sure thing is to not sand the front. But I got one article that says sand the leading edge of blade and another article that says sand the back side [] So how am I suppose to decide which is correct, or if it even matters?

TFF

The face of the prop is the back side. Most say sand the back but the front is more right because it changed the thrust less when modified. It is really what can you get away with. I sand the front first and if I need a little more the face is fine. You dont want to change the camber on the face. My BUT is do what works for you.

N1EDM

My Feedback: (2)

Here's another tip, if you like. I use acetone to remove the finish from the front (i.e., label side) of the 'heavy' blade. In many cases, that's enough to bring a prop into balance. Then I shoot the entire blade with Krylon clear. Shooting the entire prop will protect the now-bare wood and by shooting the whole prop, it doesn't re-introduce balance problems.

As a bonus, when I look at a prop and see that the logo has been removed (from at least one blade) then I know that the prop has already been retouched.

Take the usual precautions when using something like acetone (ventilation, gloves, etc. Read the safety instructions on the can).

Just my $.02

Bob

splais

My Feedback: (25)

Do you realize that what you just wrote is about the most confusing thing I ever read. "The face of the prop is the back side"! What on earth does that mean?

acerc

splais, I sand the front of the prop. Sanding the front is not going to have any effect on the pitch which is what is grabbing the air. For what it's worth the front for me is the side facing forward. BUT! In simple aeronautical terms the face is the flat side of the blade, in our use the side facing rearward.The following article covers props real well, http://www.experimentalaircraft.info...ropeller-2.php

splais

My Feedback: (25)

OK, so I have been unconfused at last. So the back actually faces front - go figure

PS: I guess a prop doesn't have a "front"

LesUyeda

"The only sure thing is to not sand the front."

Since the prop is actually a small wing, that goes round and round; you want it to act like a wing, with the airflow being similar. Sanding the front, will change the airfoil, and thereby, the airflow.

Splais. I don't know where that picture came from, but I would argue with its definition. The camber is the underside, in my definition.

Les

splais

My Feedback: (25)

That picture came from the referenced article in the link a few posts above. Non of this is getting any clearer AT ALL. What should be a simple subject has gotten way to complicated

What I consider the "front" of the prop (which is the side of the blade facing forward) has the airfoil part of the prop and is what generates the lift (pull) of the prop. To me, this is not the part of the prop you would want to change much. The "back" of the prop which according to the article is actually the "face" is the part that cuts into the wind, but it is flat and it would seem sanding this side of the blade would have little effect on performance. Have no idea about the article that told me to sand the leading edge.

And I still don't have a link to something definitive on this.

abufletcher

Schrödinger's cat is quantum child's play next to balancing a prop!

abufletcher

Here's link to an RCU discussion I started a while ago about balancing large props.

http://www.rcuniverse.com/forum/m_11...m.htm#11332975

LesUyeda

I would consider "leading edge" and "front" to be two different things. I would consider the leading edge to be the sharp edge of the prop, where all the left over flash is; sand to remove that.

Les.

TFF

http://www.zingerpropeller.com/Ballance.html
http://www.apcprop.com/v/html/balancing.html
http://www.bolly.com.au/1998%20Bolly%20Book%20v3.pdf
http://masterairscrew.com/images/selecting_a_prop.pdf
here is some of what the prop makers say.