I was wondering if nylon props being used on a nitro engine need to be balanced...I was looking to throw a new prop on my nexstar before I go flying tomorrow but I was sure if they need to be balanced......and I wouldnt want to damage the engine......

If you're going to be with the hobby for some time , getting a prop balancer is a good investment. Severly unbalanced props will cause a lot vibration to the whole plane. Most new props are pretty well balanced and I've found APC's to be the best.

thanks for the advise...so how so I go about balancing a nylon prop...how do you go about shaving a prop?.....

If you have a balancer, even a finger one: you hold it until you determine the heavy side. Then I take an Xacto knife and scrape the heavy side a bit. I always scrape on the front because that is the side that is least effected by and distoration. Scrape a little bit at a time until you have it in balance. I know other people who do the opposite and add weight to the light side. Usually they use a little paint or epoxy until it is balanced.

I would never run an engine without balancing a prob. I've also had good luck with the APC being pretty close on balance.

I have a Great Planes prop balancer. You can get them from Tower Hobbies for about $20. They are a good investment if you plan on being in the hobby for a while.

THanks
Barry

The front of the prop is least affected by distortion? The prop is an airfoil, and must remain so to be effective. Shave some off the top of your wing and see how it's affected by distortion. I wouldn't bother balancing props--you're asking for trouble. Either way you do it, you're creating drag to the airfoil, which washes out any positive effect of balancing the weight, IMO. If you have a severely out of balance prop, throw it away and use a different one. I've used hundreds of props, and have yet to experience a "severely out of balance" prop. maybe in the old days, but I simply haven't had that problem. If it's a very expensive prop that is severely out of balance, send it back and get a replacement before you use it. props are produced to pretty good tolerances. Single cylinder engines are inherently out of balance anyway.

Always check your props for balance. Due to the material and construction method, composite props are usually pretty much in balance. I like to use the tried-and-true Dubro Teeter balancer.

I strongly disagree with shaving the front, back, or trimming the tip of a prop to balance it. One may change the airfoil, one may change the pitch, and one may change the dynamic balance. I simply spray a light coat of clear poly-u on the front of the light blade. If it takes more than 2 or 3 light coats, trash the prop.

Contrary to 2slow2matter's opinion, I ALWAYS balance my props. It's true that 2-stroke engines are always slightly out of balance, but why make the situation worse by running an unbalanced prop?

Dr.1

before i sand/scrape i use clear fingernail polish,if you have a prop that is much more out of balance than that like was said trash it.if you do sand i have done this,all the prop manufactures recommend sanding or applying any coatings to the front outer sections.here is what master airscrew says about them.
http://www.masterairscrew.com/techbull.asp#F

this is from zinger,i think wooden propellers though.

http://www.zingerpropeller.com/Ballance.htm

hope this helps...happy flying