RADIO CONTROL SOARING
Mike Garton, 2733 NE 95th Ave., Ankeny IA 50021 E-mail: [email protected]
This month's column is aimed at those who want to get started in Radio Control (RC) gliders. The discussion includes a basic description of thermal and slope soaring, common mistakes new fliers make, and recommendations for first airplanes and radios.
Thermal Soaring
Thermal soaring is the art of guiding a glider into a rising air current and riding it upward. Thermals are generally shaped like tornadoes: larger in diameter up high and leaning downwind.
Thermal activity at low altitude is most common between midmorning and late afternoon. Lots of sunshine over varying-contrast ground is a sure recipe for thermal activity. The cumulus clouds that look like flat-bottomed cotton balls are each sitting on top of a thermal.
#### Launching for thermals: the hi-start
Before a glider can find a thermal, it needs initial altitude. Thermal trainer gliders are usually launched with a hi-start, which is made from 50–100 feet of surgical rubber tubing and a few hundred feet of line. One end of the rubber tubing is staked into the ground, and the other end is tied to the line.
The line is pulled downwind to stretch the rubber and is hooked to the glider with a simple metal ring. When the glider is thrown, it rises into the air like a kite being pulled up. As the model flies over the stake, the ring simply falls off the tow hook. With a little breeze, a hi-start will put a glider several hundred feet into the air.
#### Finding and centering thermals
To find a thermal, the pilot usually flies a search pattern while watching carefully for variations in airspeed, altitude, and attitude.
- If the airplane hits a thermal head-on, it will usually raise its nose and may stall.
- If the glider hits the edge of a thermal, it will bank away from the center. An alert pilot will notice the wing rock and turn back into the thermal.
- Turning slow circles within the thermal maximizes climb rate. It is common to stay up for 15–20 minutes before the thermal blows downwind and the glider is forced to move on.
A good pilot with a large glider can often stay up all afternoon by finding many thermals in succession.
Slope Soaring
Slope soaring is where a glider surfs on wind that is forced to rise over a hill. The wind must be blowing almost directly at the hill.
Pilots launch from below the lip of the hill when possible because turbulence right at the lip makes it a less desirable launch point. A good throw with a nose-down attitude will usually give enough airspeed to get the glider into the lift.
The quality of the lift depends on the strength of the wind, how perpendicular it is to the slope, the size of the slope, and the shape of the slope. Trees or other obstacles upwind can make the slope lift turbulent.
Once the glider is flying, the pilot can explore the lift band to find where it is strongest. The flight pattern is somewhat like surfing: turns are made away from the slope. When the wind is brisk, heavy, fast airplanes can fly. Low drag and high weight are two of the essential ingredients for speed.
There are organized slope races for gliders and a sport known as slope combat. In slope combat each pilot flies a simple, inexpensive glider made from expanded polypropylene (EPP) foam and tries to knock other gliders down by ramming them. Slope combat gliders are designed to withstand midair collisions and resulting crashes.
Many pilots use the slope to try aerobatics. If the glider is equipped with ailerons, it can roll and fly inverted. These maneuvers are possible without ailerons but are not easy.
Building vs. Buying
Those who don't want to build can buy an ARF (Almost Ready to Fly) glider. Imports from third-world countries don't cost much more than kits. Flaps and ailerons give added capability for "crow" landings, but are not suitable for a first-time glider builder.
Building a glider from a wooden kit can take 20–80 hours of assembly time. Twenty years ago everyone had to build their own gliders; now inexpensive manufacturing offers alternatives. An ARF typically requires three to 10 hours of assembly and radio installation.
A second consideration in choosing a glider is proximity to a slope. If you have access to a nice hill for slope soaring, it is the easiest way to learn.
Durable beginner models
- Zagi LE flying wing (Trick R/C): Costs roughly $45 (plus radio), takes 3–6 hours to construct. Designed for slope combat and durable in crashes. Requires at least a two-channel radio with one mixer. With a slope, a new pilot can build up hours of stick time quickly.
- Goldberg Gentle Lady (GL) and DJ Aerotech Chrysalis Two-Meter: Recommended kits if you like to build. Both have thorough instructions and good performance; the Chrysalis costs more due to its balsa-capped structure.
- Sig Riser: A common beginner glider with fine instructions but slightly dated design compared to the GL and Chrysalis.
- Panga (Sky Bench Aerotech): A slow, relaxing glider with a 118-inch wingspan; well designed but not a fast build.
- EPP thermal gliders: Trick RC Floater and Dave's Aircraft Works TCG-3 are more durable than wood gliders but slightly heavier, sacrificing some performance.
- Hangar 9 Aspire (ARF): Prebuilt option; wing halves need gluing and radio installation. Retails around $100 and can be ordered with a matched hi-start. Available from Horizon Hobby.
- Spirit ARF (Tower Hobbies): Similar to the Aspire; has built-in spoilers that can be hooked up or left uninstalled. Also available in a Ready-to-Fly (RTF) version with radio preinstalled.
Radios and gear
For a first radio, the recommendation is the Hitec Focus III FM three-channel with standard servos. Do not waste money on microservos for your first radio—the gear sets on microservos are fragile. Standard servos are more likely to last through training.
- The Focus III transmitter has built-in mixing and servo reversing on the two primary channels. Ni-Cd batteries and charger are included for the transmitter. Dry cells are used for the airborne flight pack. The Focus III typically costs less than $100 from Hobby Horse.
- A new pilot could buy a four- to eight-channel computer radio if certain they will continue the sport, but it will probably take two years or more to fully utilize those features. Buy only as much radio as you will use immediately.
Without access to a slope, the hi-start is the best launching method for beginners.
Getting help and clubs
The number-one thing that will ensure the success of a new pilot with a first glider is seeking out the help of an experienced pilot or several pilots in a club.
- It is critical that somebody check the airframe for problems; instructions are rarely complete enough to guarantee a perfect build in isolation.
- Learning to fly is a challenge, even with a perfect airplane. If you want to teach yourself, be prepared to crash and destroy several gliders before getting enough stick time to be proficient.
- Your local hobby shop should be able to tell you the names of local pilots or clubs. If you do not live near a hobby shop, call the Academy of Model Aeronautics and ask for the nearest club contact information.
- It is worth driving a couple of hours to get help for the first couple of outings.
Common mistakes of inexperienced builders/pilots
The average person makes most of these errors sometime in the first year. Experts still make them, just less often. Many of these errors can be eliminated with a good preflight inspection before each flying session.
- Built-in warps in the airframe.
- Built-in slop in the control linkages.
- Built-in friction in the linkages.
- Accidentally reversed controls (left stick gives right rudder).
- Intentionally reversed controls (up-stick gives up-elevator).
- Did not balance the airplane as designed.
- Did not charge the battery and verify its state of charge.
- Improper assembly at the field.
- Launch with the radio off.
- Overcontrolling.
- Not finding a good, steady-state trim condition.
- Not looking ahead of the airplane during flight.
- Orientation problems while flying the airplane toward oneself.
- Orientation problems when the airplane is a silhouette.
- Orientation problems when the airplane is far away.
- Pilot-induced oscillations because of improper setup, overcontrol, and correction time lag.
Final advice
Which glider is best for a new pilot depends on how valuable your time is and whether you enjoy building. If you prefer not to build, ARFs like the Hangar 9 Aspire or Spirit ARF save time. If you enjoy building, kits such as the Goldberg Gentle Lady or the Chrysalis are excellent choices.
Seek experienced help, do preflight inspections, and start with durable, forgiving equipment to maximize your learning and minimize costly early crashes.
Sources
Comprehensive Soaring Links page: www.eissc.net/eissclinks.html
Trick RC: 938 Victoria Ave, Venice CA 90291 (310) 391-1614 www.trickrc.com
Dave's Aircraft Works: 34455 Camino del Molino, Capistrano Beach CA 92624-1070 (949) 248-2775 www.davesaircraftworks.com
Hobby Horse: (800) 446-6229 www.hobbyhorse.com
Horizon Hobby: (800) 383-4639 www.horizon-hobby.com
DJ Aerotech: 719 Pilot St, Pismo CA 93456 (805) 773-6772 www.djaerotech.com
Sky Bench Aerotech: (219) 846-1222 www.skybench.com
Transcribed from original scans by AI. Minor OCR errors may remain.
