Ok, I have one .40 size superstar trainer and a easy2 trainer converted to a float plane running a .46 engine. I'm currently using wood props. Do I need to balance these? Whats your option on this. I have some say .40 size engines don't and some you should alway balance the prop. Also, I'm using a plastic spinner on those. How do you balance those if need be.

I never use wood props.....but of all the props i've seen wood seems to be the worse for out of balance......some say you should some say you don't need to. I do balance all my props>
I figure it can't hurt anything

The problem with wood props is that the wood density on one side may be different (and often is) than that on the other side. So, in some cases, trying to balance them may cause enough distortion on one side to make the prop ineffective, or useless.

I've been using APC props now for years. They are inexpensive, and although they claim that they do not need to be balanced, I put them on the balance anyway, and often need to hit them with a piece of fine sand paper to make them balanced.. although there are some that say that it is not necessary. I do them all.. electrics as well as glow engine props. I don't know what it would be like to fly with an unbalanced prop because, as I said, I balance them all.

Your choice, though. If you like the wooden props, you may have to go through several just to find one that is correctly balanced.. then again you may not. I don't know because, as I said, I don't use wooden props.

DS.

I think I might have to switch to plastic props. There around the same price and stand up a lot better. I've heard that wood was safer for the model engine if you have a prop strike or your hand if you get it in the prop. Any truth to that?

You need to balance ALL props, ESPECIALLY WOOD PROPS. The density in each blade on a wood prop is frequently different. The easiest way I have found to balance a wood prop is to paint a bright color (red or yellow) on the tip of the light blade and let dry. When dry recheck the balance and repeat as needed. The bright color serves as a visual warning of where the tip of the spinning blade is.

APC props SAY they do not need balancing. While the majority of them are typically quite close, they are usually off a little.

Whether you fly glow, gas or electric you need to balance your props. The vibration to the airframe from an unbalanced prop can litteraly shake the firewall off the plane.

As for spinners, unless you have to cut the prop openings larger, I don't bother balancing the spinners. Any weight difference will be neglidgable AND it will be close to the crankshaft (not way out like a prop blade ) so it will have little if any effect.

If you have to enlarge the prop openings I balance mine as follows:

1. I have a 2/56 bolt that is 1" long that has a wire soldered to the middle of the bolt head.

2. From the INSIDE of the spinner drill a 3/32" hole in the tip of the spinner.

3. Insert the bolt and secure with a 2/56 washer and nut (It does not have to be tightened ).

4. Pull the bolt until it is against the tip of the spinner and then hang the spinner.

5. Mark the heavy side and carefully sand the INSIDE of the spinner.

6. Repeat as needed until the spinner hangs level.

If you are careful enlarging the prop openings this is usually not needed. If I need to enlarge the prop openings, I mount the spinner and a balanced prop on an engine and run the engine. If I have vibration, THEN I pull the spinner and balance it.

Thanks for the info! I'm off to the LHS.

If you get your hands in the spinning prop, please make sure your health insurance premiums are paid up... [:@] and that goes for wooden, plastic, titanium, even kriptonite. They will cut you pretty badly before breaking.

What do you all recommend for a balancer?

In addition to all the points from posters above I just wanted to say since it seems the airplanes you first posted about are float planes.

Wood props are almost always a mistake on a float or seaplane. Seldom surviving sometimes not more than a few flights due to spray. This varys among different designs and arrangements of the aircraft.

John

I also noticed when I broke in one of my new engines the prop seemed soaked with caster oil. I wonder if the LHS would take back the few extra wood props I bought. Worth a shot I guess. I'm in a there a lot.

opps

I had an APC prop (on a OS40) that was out of balance.............vibration was severe enough that it caused bubbling in the fuel tank and lines. This was not a problem at high RPM....but at idle, the engine would run fine for a few seconds and then collect one of those air bubbles and die. Tank and all fuel lines (internal and external) were inspected 2 or 3 times. No holes or leaks.............a more experienced member suggested checking the prop balance.......put on a balanced prop and have not had a problem since.

How would one balance a plastic or wooden prop?

Light sanding on front of prop. Do a google search for "balalncing rc prop" and you will find several webpages with detailed info.

you can also valance the prop by painting the tips of the prop. I use white or yellow paint, kinda like the full size planes, put some in a epoxy mixing cup (use a 2oz shot glass), and then dip both of the tips, let dry and check for balance then just re dip the light side. This will give you a nice visible arch when the prop is spinning. If it takes too many dips try the sanding method.

hope it helps.

Ok, I bought the Top Flite Power Point Balancer last night at the LHS and three props. All the props were Master airscrew brand G/F Series. One was a 10x6, 10x7 and I had one that wouldn't balance, it was the 11x6 prop.

This is what it was doing. This is from the manual.

If the prop comes to rest in a
level position, but is still obviously out of
balance (hole slightly off-center), you
may need to add weight to the lighter
side of the hub (see method 2).

I had a glob of ca glue on the light side but it would not balance out. Did I just get one lemon of a prop? The other ones balanced perfectly.

I balance ALL my props. To me sometimes it's time consuming.

I had to rebalance one of my props for the PTS Hanger 9 Mustang after I painted the tips yellow. Painting the tips most always makes ther prop unbalanced.

I found out the hard way when I put the prop on the plane and she started to vibrate much more than usual.

I took off the new yellow tiped blade and put my other prop on that was unpainted. ( I knew better than try to fly it that way, I don't take chances)

It took me a few minutes lightly scraping the trailing edge of the blade to balance it correctly.

I've seen planes go down, and heard of planes crashing due to excessive vibration, everyone should have there props balanced.

I know of a few who rubber mount there motors as well on the bigger planes, just to cut down on the vibration. ( But that's just another topic)


Luftwaffe Oberst
Radio Aero Modelers Club
AMA District II
Pulaski, NY

CA glue is very very light stuff.

If the prop has an off-center hole and it's an MA prop with cavities in the hub (they're visible from the back, not the front) then place a weight into one of those cavities and check the balance. Epoxy the weight into the cavity. The cavity will be sealed when the prop is on the engine, but you don't want to lose the weight later.

It's always worthwhile to check the balance. But you really don't have to get the balance dead perfect. It's nice if you do, but really not a biggie. The real value of balancing is to cull out badly balanced ones. They happen less and less often nowadays, but still do. And seems the ones you do find would be killers.