Wheel and static prop balancer

Dusting off this old thread to ask Roger, what type of wheel weights do you use and how do you affix them to the wheels when balancing? My wheels are two-piece Matco aluminum wheels.

Hi Jim,

Many of the ones I do are Matco. Mine on my Flight Design CTSW are Matco. I helped design those for FD. I use real 1/4 ounce lead weights. I buy them online. Many places have gone to tin weights which are 2-3 times the lead weight size and a pain to use on small wheels. When I use my Marc Parnes balancer I take some duct tape (rip it into 3 long narrow strips) on lets say 4 weights to start. I just tape the 4 weights at the 12 o'clock position to start (6 o'clock is the heavy point we are counterbalancing)  and then see if the tire needs more or less weight. I can usually tell if it needs a little or a lot by how fast it spins towards the heavy spot at the 6 o'clock position. I start there because most tires take 4-8 weights. I'll put 4 on the front of the wheel to start and if it needs more I put them on the backside. Once I get the tire to be dead on which usually means you turn the tire to any position and it stays there without turning by itself. Then I take it off the balancer and then use a magic marker to put a mark on the wheel where the new permanent weights will go. Then I remove my test weights. Then I was told this by some tire stores to take lacquer thinner and clean the area where I'm going to stick the weights. I was told to clean it three times. Then I peel the paper off the back of the weights and stick them on. I usually take a small plastic hammer or flat object and kind of tap them down in place to make sure the sticky surface is flat and there is no air bubbles under the sticky part that might cause a weight set to loosen.  I've been doing it this way for more than 25 years and I don't have weights come off and the tires are balanced and don't shake the plane.

Balancing a tire takes me maybe 10 minutes.

I buy my tires and tubes from Desser Tire. If I remember right you can ask them to pre-balance the tire before they ship it which helps make sure you don't get one of the really bad out of balance tires.

Interesting!

My last aircraft had a Fiti, two blade, ground adjust, composite, propeller. The blades were easy to remove from the hub, so static weighing was a doddle.

Not having prior experince in balancing, I came up with the following:

Laboratory electronic digital scales (left over from my paid life) but any quality scales would do the trick

Two short lengths of aluminium angle. One cut to suit on the scales (bridge) the other on a piece of plywood (bridge). The apex of each angle exactly the same height.

Scale placed on level flat workbench - position of scale, marked on bench, "ditto for bridge". Position of scale bridge marked on scale. The marking is necessary for repeatability.

Note: Scales tared of/zeroed (with bridge) between each weighing.

Each blade had piece of masking tape wrapped around the chord, at the 750mm measured from hub. The exact 750 mm point carefully measured & marked in with a nice sharp pencil.

Stage 1.

Each blade was weighed horizontally. Using the aluminium bridges as the exact resting point for both at hub/750 mm end. Alternating between tip on scale & hub on scale, I recorded the weights.

Stage 2

Each blade was weighed in its entirety, by balancing the hub end/blade vertical on the scales (must be in draft free room/area) and recorded.

With the information gathered I was able to determine a light/heavy blade & the weight distribution. Turned out the tips were almost exactly the same weight with the small difference being concentrated at the hub.

It seemed easier to me, to add weight than subtract. I weighed a number of variations of  nuts + bolts + washers, until i found a combination that made up the difference between the two blades.

The aluminium hub had a handy hollow that allowed me to place the weight in a nice secure spot - weighed again to check - all good - small quantity of epoxy (weight allowed for) then secured the nut/bolt/washer weight in position.

Assembled & adjusted pitch.

Aircraft flew with no discernable propeller vibration.

Some months later, I had a professional Dynamic Balance done - A small number of M6 washers were added to the inside of the spinner. On the flight home I tried, at various rpm, to see if I could notice any change - no  apparent improvement over the Static Balance.

Despite there being no discernible improvement,Static to Dynamic Balance, I still think a Dynamic (after a carefully Static) is a good investment in your engine/gearbox/avionics and possibly the airframe wellbeing.

Just a note**

Remember the human ear can't hear some things and the body can't feel many vibrations, but the engine can vibrate without you being able to tell and over the many hours uncorrected vibration can and will damage gearbox's and other things.

Hi Roger,

Now that you have delved a little deeper into prop balancing (PB), how about a bit of a refresher on Dynamic Balancing:-

# Advantages (Pro) V Disadvantages (Cons) ?

# Standard - what should be the vibration goal (mm/s & ip/s) ?

# Is it true that a very precise balance, will only last until the next bug splatters itself on the prop?

# How often should a PB be done, assuming no prop damage ?

# Is it worthwhile having your own balancing equipment (eg Dynavibe) ? or is this more of a group/club investment ?

# Can you recomend a cost effective "home/ semi professional " PB system ?

# Anything else ?