Author: Dave Garwood
Edition: Model Aviation - 2008/08
Page Numbers: 134,135,136
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Radio Control Slope Soaring - 2008/08

Dave Garwood [[email protected]]

In the great Northeast we have wind and plenty of hills, but so often they are covered with trees. We have suitable terrain and plenty of wind for slope soaring, but trees keep the pilot from seeing the sky and rob us of landing areas.

Finding slope sites in New York and New England generally means looking for hills with clearings. Another characteristic of a great flying site is water in front of the hill. Wind passing over water is smoother than wind passing over terrain, and it makes for smoother lift. We like flying with an ocean, a lake, or a river out front.

The eastern shore of Lake Ontario presents a productive slope-flying site at Sterling, approximately 30 miles northwest of Syracuse and roughly 15 miles south of Oswego. At Sterling bluffs we have public-park land that includes a 100-foot, northwest-facing hill with water upwind, a 300-foot ridgeline clear of trees, and a huge, grass-covered landing zone (LZ).

The LZ may be the flying site's best feature; it slopes gently toward the lake and serves well for test flights of a new sailplane—a final check of balance and control throws before committing the model to big lift. The landing area is the size of a football field and not only makes landing for beginners a snap, but also allows safe landings of large, fast sailplanes.

One drawback to the site is recovery of a downed model out front. The gravel-covered beach is approximately 3 feet wide, and the steep slope gets muddy in damp weather. It is possible to recover a model on the slope face, and there are paths to the beach, but recovering out front is not nearly as pleasant as a walk through the pasture at the top of the ridge.

We don't do a lot of foamie combat here. One other possible hazard is the trees on both ends of the ridgeline. There's roughly 300 feet of cleared corridor between the tree lines, but it's possible to get in trouble with them in certain moments of inattentiveness. I remember a time when Wayne Rigby was flying my scale Mitsubishi A6M Zero. I had built four slope scale models at that point and wanted to get Wayne hooked on these "iron horse" warbirds. During the flight, which he appeared to be enjoying, I mentioned that I bought the glider built and finished for $350. It had been through a lot and had received many repairs, but it still flew extraordinarily well. I told him I figured it was 90% used up and that I'd sell it to him for $35 plus the two $10 servos. Wayne said, "Okay," and before the next turn the Zero flew into the trees. I figured the title to the aircraft passed at the moment Wayne said he wanted it, and it was his airplane. The Zero fell out of the tree and, in typical style, had no more damage than a 5-square-inch chunk torn out of the wing leading edge and the foam-core-sheeted wing. I repaired the wing damage, Wayne refinished the sailplane, and he flew it for five more years. A $350 model is cheap if you fly it 350 times.

Although Buffalo, Syracuse, and Albany slope pilots flew at this site in the past, we did not write about it because we were unsure of the land ownership. Now it is a Cayuga County park, and we know we are not trespassing. We mix in with the hikers and picnickers, and we pack out our trash.

A trip to Sterling becomes a priority for me when we have 20 mph winds from the northwest in the National Weather Service marine forecast. I've flown a Bob Martin Coyote in 5 mph wind there. Almost any foamie will fly at 10 mph. At 15–20 mph, you can rip up the sky with F3F racers and scale iron horses. Sterling is the flying site where, on one memorable day, Joe Chovan and I decided that a 60-inch-span Leading Edge Gliders warbird was a must-have sailplane.

To get to the ridge, drive to the end of McIntyre Road as shown on the online map, park at the barrier, and walk a few hundred feet westbound down the gravel road. When the trees on your left open up, head into the open field, where you'll find trails through the tall grass. By now you'll see gulls and turkey vultures slope soaring. Just walk to the edge, launch, and fly.

Did I mention that the lift is good at this site? Yeah — it is, in spades!

Potting Servos

EPP foam is terrific for airframe construction in models that need to land in rough areas and survive collisions and bad landings. This material's springy action is an advantage in shrugging off impact damage, but it can make it trickier to install tight servo linkages.

"Potting" a servo takes care of this problem. The more "slop-free" a servo linkage is, the more accurately the control-surface positioning will be. This includes the desirable trait of having a servo consistently return to the same center point after being deflected in either direction.

We go to some trouble in servo-linkage hardware selection and fitting so that all parts move freely, without binding, but have no extra clearances that would cause play or looseness. All components can be carefully installed, but a servo mounted in a slot cut into the foam alone commonly exhibits movement as the control surface is deflected. EPP foam has give, so the servo moves in use.

An easy way to eliminate the foam flex and the servo movement is to "pot" the servo in epoxy that surrounds it in the locator slot cut into the foam. This makes a rigid, tight-fitting receptacle that is bonded firmly to the surrounding foam.

Procedure:

  • Cut a slot for the servo with a blade and remove the excess foam with small-nose pliers or a rotary tool. Making the hole slightly oversized does not present a problem with this mounting method.
  • Mix a small batch of epoxy and add microballoon filler for weight reduction and to make it easier to cut or grind off excess epoxy. Use approximately a 1:1 ratio of epoxy to microballoons.
  • Put some epoxy/microballoon mix in the slot and lay one thick or two thin sheets of plastic over the hole (a plastic bag or two sandwich-bag thicknesses work well).
  • Press the servo and bag down into the slot until the servo reaches its intended position. The epoxy/microballoon mix should ooze out on all sides. If it doesn't, remove the servo and the bag, and add more mix.
  • When the epoxy has cured, remove the servo and carefully peel the plastic out of the slot. Remove hardened oozed-out epoxy with sandpaper or a rotary tool. You will now have a rigid servo slot with enough clearance to get the servo in and out easily.
  • Finish mounting the servo with a dab of Goop or silicone glue on each of its long sides, and let that cure. Apply this adhesive so that when it comes time to remove the servo, running a blade along the sides will free it from the adhesive and make it removable.

I have finished construction of three new foamie sailplanes for the cross-country driving trip to the Midwest Slope Challenge in Kansas. Each of the new models has potted servos. Shown is the servo in the Leading Edge Gliders P-80 Shooting Star wing. I potted aileron servos in the new SkyKing RC Products DAW Schweizer 1-26 wings, and I did so with both aileron and elevator servos in the Magnum Models F-5 Tiger.

Good Equipment

I purchased a Peak Electronics SuperTest Pro lab-quality battery tester and soon wondered how I ever maintained RC airplanes without it. I think I have discarded too many good receiver battery packs and continued to use marginal packs.

To use the instrument, charge a transmitter or receiver pack and connect it to the tester. The device slowly discharges the pack and records its capacity, letting you know if the pack is delivering its rated capacity. If it's below 80% capacity, discard the pack.

In the first two weeks I used the SuperTest, I found two 10-year-old receiver battery packs still putting out their rated capacity and four packs of various ages that were substandard. Using this device delivers great peace of mind. RadioShack stores accept old batteries for recycling or environmentally friendly disposal.

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Transcribed from original scans by AI. Minor OCR errors may remain.