stunthanger.com
Engine basics => Engine set up tips => Topic started by: Kim Mortimore on October 16, 2007, 08:36:46 PM
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I haven't flown with wood props for years, until recently at the field I had left my only APC 11-5 at home and asked if anyone had an 11-5 I could use on my Brodak .40. A friend said no, but he had a Top Flite Power Point 11-6. I said what the heck and gave it a whirl. What an eye-opener! I had gone thru about half a dozen different props looking for the right one, all APC and Thunder Tiger, except for one carbon and one MA 3-blade. Several had been OK, and the engine was medium happy with a wide range of sizes, but the Top Flite really woke the engine up. It produced more power, better line tension everywhere, especially overhead. Maneuvers felt somehow crisper to me, although I'm not sure if I might be reading more into it due to my enthusiasm. Possibly the lighter weight beechwood has something to do with this.
Anyway, I noticed that the prop is starting to fuel soak. I ordered a half dozen more, and I would like to do a little sanding and rattle-can clear refinishing to improve fuel resistance, and possibly (if this works) to balance the prop by spraying extra finish on the light blade.
Any suggestions as to a fuelproof rattle-can clear to use on props, and any other points?
Thanks,
Kim Mortimore
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The only fuel proof rattle can clear that I know of is clear Lustercoat---some others are fuel "resistant".
I just use thinned Sig Supercoat clear and brush it on, L'coat being closely related to $$$cote.
Cheers,
Jim
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What I use is a trick taught to me by Pat Johnston so I take on credit. After sanding and balancing, reshaping or repitching, I use finishing epoxy brushed on and let sit for a few minutes. Then wipe it dry. Pat sets his oven for I think 200? and as soon as it gets there he turns it off, I cant do that, the girlfriend isnt real freindly with epoxy and dinner mixed. Do this three times, wipe on, wipe off, and cure, lightly sand with 600 between coats. REally makes a nice tight finish and it hasnt caused any balance changes in the props I have done. I have used spray lusterkote and it HAS caused some balance changes for me in my experience. I like the epoxy better because it seems to strengthen the wood as well.
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Use minwax polyurethane varnish and rub it into the wood with a lot of enthusiasm. This can take a while to dry but it gives a good fuel resistant finish.
H^^
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I just use rattle can spray polyurethane, look at the can and if it says something about being alcohol resistant after cured it will be fuel proof. Light coats on the heavy blade and heavy coats on the light blade.. Spray the hub also, this is where fuel enters the wood.
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The way i do it, i learned from Windy, and thats to use CA. Put a lite coat/thin, let dry then sand lightly with 220 and repeat a couple of times. I have not had to re balance after, also hardens wood. You can also use this to harden wood in other areas of the plane when building and another plus is you can use up your old CA in this manner, as long as it still gasses off. IMHO y1 y1 Ron.
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Lots of good replies, lots of possibilities for finishing materials. Thanks, guys.
Kim Mortimore
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Epoxy fumes and food are NOT a good combination. Don't! But a heatgun...or a warm heater duct...no harm, no fowl (sic). LL~ Steve
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spoilsport Steve, jeez, your as bad as my girlfriend! actually I have one of those radiator styled heaters that keeps the back bathroom warm, it works pretty good as well. On the subject of epoxy being not good, it really is one of the more problematic chemicals we deal with, there are a great number of people who develope allergys to epoxy, latex or Nitrile gloves are a really good idea when working with epoxy and no Benzyne based cleaners or solvents from what I recall, it actually makes it easier for the chemicals to penetrate the skin.
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Anyone tried timber oil of beeswax to feed the timber and make it tougher and more resiliant ?
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Kim,
Pardon my ignorance, but is this a modern day Topflite Powerpoint prop (aka a Paint Stirrer? S?P ) If it is, was it cleaned up or stock?
Thanks