Prop balancer?

They, do, kinda...

It's one of those "just to be on the safe side" things.

I always check the balance of any new prop - after boiling to relieve any moulding stresses and ensure a reasonable moisture content with nylon props - and can't remember when I found one that didn't need some attention especially if there is any moulding flash or remnants of sprue.

Sometimes one seems OK until I turn it over on the balancer and then it seems way off - one side of the hub proves to be heavier than the other - or the hole is slightly off centre.

Malcolm

Often plastic props are very close, even after sanding or scraping of the mold flash. However, I have never seen a wood prop that didn't need some adjustment.

I always clean up the flash and balance any prop , plastic or otherwise. Very seldom do I come across one that does NOT need balancing. After making contact with a hard surface such as asphalt or concrete and scuffing the prop I rebalance.

Ken Day

Most composite props will be in balance due to the manufacturing process: cast or injection molded with a constant weight material. Wooden props by the nature of the material should ALWAYS be checked for balance. If the heavy blade bangs down on the table, take the prop back, it's too far out to save. If it swings down slowly or hits only lightly, spray clear poly-U on the front of the light blade. I'm generally against sanding a blade to balance a prop, or doing anything to the back side since that's where the pitch comes from.

Dr.1

Nylon??? Are they even made any more? I remember having to boil pure nylon props, and I sure as hell wouldn't use a nylon prop on anythnig larger than a .09, or ANY type of high RPM engine.

Dr.1

After making contact with a hard surface such as asphalt or concrete and scuffing the prop I rebalance.

You're taking big chances, any prop that contacts a surface such as asphalt or concrete should be thrown away and replaced.

Dr.1

You're right Dr1 , I should have elaborated on what I meant by scuffing...like on those bad landings when you nose over and scoot on tip of your prop a ways....stuff like that. Then I would clean up the tip and rebalance , but not with a wood prop. I would never use a wood prop that hit anything at all. Thanks for pointing that out.

Ken

There are still a number of plastic props available which may or may not be nylon. Some nylon props are "glass filled" and much more rigid than pure nylon.

I don't know what plastic Graupner use for their props but they recommend boiling for a few minutes or soaking in cold water for a couple of days.

I have a number of Kavan props in a range of sizes which are also boiled from time to time.

"Bendy" props are useful on sport models and control liners having no undercart - they last more than one flight.

I have never had any plastic prop, nylon or whatever, shed a blade except during the occasional violent contact with terra firma and have used them on engines from .020 up to .60 cu. in. capacity.

Often I carve my own props from suitable hardwoods and find my balancing jig invaluable for these.

Malcolm

I have seen many that ran fine - I have seen a few that bounced around really bad, but ran fine after balancing.