RADIO CONTROL SOARING
Peter Carr 2030 Sturbridge Dr., Columbus OH 43209 E-mail: pscarr@juno.com
About the author
I'm Pete Carr from Columbus, Ohio. I'm a Contest Director, AMA 536, with a ham ticket of WW3O, and I am a past-president of the National Soaring Society.
I'm working on the eight-hours and distance tasks to finish LSF Level V (since 1982!). I also subscribe to the R/C Soaring Exchange and welcome postings from you all.
I'd like to commend Dave Garwood for the fine work he did as your Soaring columnist. Dave did a wonderful job of bringing us a cross-section of activities from around the country. His interviews with the "legends" of soaring were particularly interesting to those of us who are working to master the seven-minute task.
Cumberland Soar-for-Fun (Old Knobley Hill)
Late October is the time of year for Cumberland, Maryland and the annual Soar-for-Fun. Old Knobley Hill is a westward-facing slope with a beautiful view, located just west of town. RC pilots gather here for one last flying session before winter's arrival.
The site is a meadow, with a row of low trees near the edge of the slope that can cause severe turbulence to low-flying airplanes. When the wind is up the hill and blowing, it is possible to hand-launch even the biggest models by punching out through the rough air.
The 1998 gathering was a case of good news/bad news. The good news was that the tree line didn't produce the usual "chop" because of the bad news: there was no wind. A high-pressure area sat over the hill, producing beautiful, cloudless skies and still air. As a result, pilots were forced to winch-launch or use two power airplanes to reach altitude on piggyback.
Skip Schow has organized the affair for several years, and has arranged for food, a winch, and a Saturday night banquet. The local club built a small wooden building with large windows at the top edge of the meadow. In previous years, when the wind was up and the temperatures were down, it was possible to slope-fly for hours while seated comfortably in this building. This year, the building served only for food preparation as warm, calm weather prevailed.
One of the icons of the contest circuit in the 1970s, Otto Heithecker, visited the Hill. He designed a three-meter sailplane called the Challenger that used flaps and spoilers for glidepath control. The radios of the day were quite large, so the cockpit of the Challenger was roughly four inches wide. Otto and his model were the combination to beat at contests on the East Coast.
We chatted about those times and he mentioned that he had gone into full-scale soaring, which he still enjoyed. His presence at Old Knobley Hill was the highlight of the weekend.
Ray Hayes of SkyBench Aerotech in Michigan is producing kits of Otto's Challenger, complete with a Clark Y airfoil and the original construction article.
Saturday's banquet was attended by Gene Shelkey, AMA Soaring Contest Board Chairman. Gene flew a Sailaire to many wins on the East Coast and is well-known for his scale Schweizer sailplane called The Great Pumpkin. We are lucky to have Gene and his fellow board members looking after our interests with AMA.
Servo mounting methods
Methods for mounting servos in wings are like opinions — everyone has their own. If you are looking for alternatives, post a question on the Soaring Exchange and be prepared for E-mail overload.
Three methods have gained recent favor:
- Wrap the servo in tape, then epoxy it into the wing well against the sheeting. Removal is by cutting the tape to free the servo.
- Fabricate a servo box snug enough to keep the servo from twisting under load. Epoxy the box into the wing with MonoKote or similar trim-sheet covering the opening in the wing. Removal involves cutting the trim-sheet covering and lifting out the servo.
- Use double-stick carpet tape to hold the servo in place in open-bay wings. Glue a plywood plate between two ribs, apply tape to the servo case, position the plate, and drill the plate so a nylon tie can hold the servo in place. This works particularly well for spoilers directly actuated by a wing-mounted servo.
EPP foamies
Expanded Polypropylene (EPP) foamies are nearly indestructible models. Slope combat events would favor EPP foam construction of tougher models. For new pilot training, no model can take nose-first landings or trips into trees like EPP; they seem to thrive on abuse.
Because the threat of damage to the model becomes a low priority, the new pilot can relax and concentrate on learning. Fewer repairs also mean the new pilot gets to fly longer using the same airplane, which improves the learning curve and makes the whole experience more enjoyable. Makers of EPP models would find a market for beginner models. F3B might interest a whole new group of pilots who could learn various tasks without risking kilobuck-worth sailplanes. An Esteem or Prism replica made of EPP would be a very interesting training tool.
Servo specification
Servo specifications take some very careful reading. The three big numbers are speed, torque, and voltage. Sailplane builders understand that no two control functions will take the same servo power to activate.
Most radio systems come with three or four servos of the same size, so there is little chance that the stock servo will be the right one for each application. Flaps, for example, need a lot of power but must be small enough to fit inside the wing. By comparison, the rudder requires far less power, yet size is less of a consideration.
In an effort to make their servos seem more powerful, some manufacturers quote their specifications at six volts. This would be like using four dry cells or 1.5 volts as the flight pack battery. Most servos will operate just fine on six volts, but most sailplanes run on 4.8-volt rechargeable batteries. This impacts the speed and torque numbers, and also the current drain.
To further cloud the issue, some servos that are physically large have less speed and torque than some smaller units. This may be because of the use of cheaper motors, since they are also lower in price. The compromise of numbers for each control can take as much thought as the choice of airfoil.
Aerotow '99 — Elmira
Dates for the 1999 edition of Aerotow "99" Elmira are June 10–13. John Derstine has coordinated this event the last several years in conjunction with the Harris Hill Museum and the Harris Hill Soaring Corporation. Acting as cosponsor is the Eastern Soaring League, which will assist with flightline and field operations.
In addition to scale sailplanes from the U.S., EMS of Germany will return with some new aircraft, including the new Discus II. They will also produce a UHF version of a thermal telemetry system that is very small and operates from the flight pack. These may also be on display.
Launches are by aerotow, where a tow plane uses a long line to tow a sailplane to altitude. This calls for close cooperation between the pilots. When properly done, the resulting flight is an exact miniature of full-scale flight operations.
Harris Hill is a unique site because the runway ends at the edge of a very steep slope. With wind from the northwest, it is possible for a sailplane to do a touch-and-go, then fly off the end of the runway into the lift and climb out again.
Combined with the exhibits at the Museum and the full-scale sailplanes of the Harris Hill Soaring Corp., Aerotow '99 will be a modeler’s and a photographer’s delight.
Transcribed from original scans by AI. Minor OCR errors may remain.
