Sm Tall alk M
any years ago a friend that I flew with regularly started skip- ping a day here and a day there when winter came around. I asked him one time after not seeing him at the field for a month or so what the deal was. He said that he was simply not able to han- dle the cold like he could in his younger days. Well guys, I can definitely see where he was coming from now. My tolerance for cold temps is definitely at an all time low too, and now I find myself watching the weather a good bit more closely than in years past, and picking my flying days a lot more carefully.
Something else I see developing into a trend in recent months has been servo fail- ures in colder temps. “Back when”, I would fly in temps from about 10° on up and don’t ever recall a temperature related servo fail- ure, but over the last couple of winters when the temp dips below freezing, servos start dropping like flies.
Now grant it, I’m not buying the latest and greatest high dollar state of the art stuff, but even using the lower cost equip- ment, failure rates of 25–30% are getting hard to take. We’ve even seen a rash of Hitec HS-55s bite the dust over the last month or so. And it’s not just in airplanes either; I’ve had a rash of small servo failures in boats lately, too. I certainly hope this is not an in- dication of declining quality of the compo- nents coming from China, or worse, what we might come to expect as the new standard for the industry? We will definitely be keep- ing an eye on this one.
Selecting the right motor I get a good bit of mail asking about select- ing a motor when converting wet fueled models to electric power, so I thought it might be a good time to touch on the subject. Don’t worry guys, I’m not going to turn this into an “Electric Column”, and I promise not to step on Stew’s or Don’s toes, but instead will offer the simple, low tech method I’ve used to pick power systems for electric mod- els from the beginning.
What it boils down to in simple terms is
by pat tritle You can reach Pat Tritle at 10313 Snowheights NE, Albuquerque, NM 87112 or via e-mail at
patscustommodels@aol.com
PHOTO: PAT RYAN
Every shop needs a few models hanging from the ceiling to set the mood for building, and Pat Ryan has done just that with several Dumas kit builds. A handful of plastic scale models grace the ceiling as well, built to honor his Dad and Uncle who flew in WW II.
“watts per pound”. In the spirit of simplicity, watts are just a measure of power; 746 watts = 1 horsepower. Then to determine just how much power you’ll need to fly a given model, the best indicator will be in watts per pound. And since we’re dealing with “Small” models, we’ll keep it in the Park Flyer realm and work with models weighing in at two pounds or less, though the principals are the same for any size model.
So here’s how it all breaks down: First, PHOTO: LEN ROZAMUS
guesstimate the weight of your finished mod- el, it doesn’t have to be precise, close is close enough. Then for models with a wing loading of 10 ounces or less, 45–50 watts/pound will give good solid performance for scale models. For an aerobatic sport model that will do ba- sic aerobatics, 75–100 watts/pound will work fine. For an all-out 3D acrobatic model, 175– 200 watts/pound will do the trick, though a bit more won’t hurt.
Now, since we’re talking watts per pound,
PHOTO: PAT TRITLE
Pat’s Stinson Reliantwas built from the Dumas 30-inch rubber kit (above) and is scheduled for an electric power conversion to replace the original rubber system. Len Rozamus pulled the Sterling Corsair(at right) from his attic and is planning a full restoration for the model. Restoring an old “false start” is a lot of fun, and even if they don’t get flown are great insights into the modeling style from years past.
52 MARCH 2014
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