Motors can be fun, but it can be thrilling to soar without one. Soaring becomes a “game,” testing your skill in a constantly changing aerial environment. This experience is quite different from using gas or battery power. While soaring, external energy provided by the environment is used to gain and maintain altitude. To a glider pilot, altitude is stored energy—like gas in a tank. It takes knowledge and skill to extract this energy from the air. A famous aviator (who started as a modeler), Dr. Paul MacCready, had a motto of “doing more with less.” This minimalistic approach captures the essence of soaring.
Not all sailplanes are created equal. You’ll want to choose a model that matches your skill level and the type of flying site available. Starting with an inexpensive foam or balsa model allows you to learn without risking a costly airframe.
Classes of RC gliders
(based on wingspan): Class A (60” wingspan) Class B (2 meter) Class C (100”) Class D (>100”)
For each type of soaring (detailed below), there will be specific gliders that use specific lift in the air. Determine the type of soaring you’ll be doing and use the following tips to pick your plane!
The majority of thermal soaring is done with large Class C or D gliders in competitive formats. These gliders test pilots for their ability to soar for a specific duration and their ability to land at a precise location at specifically the required time after a thermal flight.
Pilots start their Class C or D flight by using a winch or a “hi-start” (rubber tubing with a string) to launch the planes into the air. For Class A, the common launch method is “discus launch,” during which the pilot holds the plane by a wingtip, spins and throws the glider into the sky. While this results in a launch of only 200-300 feet above the ground, good pilots are able to keep their RC gliders aloft for long durations if they know how to read the thermals properly.
Another less common aspect of thermal soaring is cross-country soaring. Pilots launch their gliders, ride thermal currents to altitude and hop in a vehicle to follow their glider as it goes for a distance. This special type of soaring requires a large suitable area, a team, significant planning and, in some cases, airspace permission. Cross country soaring is for advanced pilots.
Some modelers specifically create and scale their planes to look as close to real sailplanes as possible. These enthusiasts enjoy flying their scale models in a manner that may trick a bystander into thinking their model is a real plane! Scale models are generally large and expensive. There are, however, myriad small scale models available— even some made out of foam suitable for beginners. Scale sailplanes can be flown using slope or thermal lift, and pilots generally launch their planes using aerotowing (towing the RC model sailplane behind an RC model powered towplane) just like the real sailplanes do.
Soaring is like fishing. To catch a fish, you have to understand its environment and its instinctual tendencies. To keep a sailplane aloft, you have to understand its environment and the way it reacts to it.
Due to the force of gravity, gliders are continuously falling. A good pilot learns where to look for lift in the air to maintain or gain altitude. Without this knowledge, flights will be short and often frustrating. Encountering and understanding lift in the air for the first time, however, can be an extremely rewarding experience.
To pick a flying site you have to understand there are three basic types of soaring based on lift in the air.
Makes use of lift created when wind hits a hill or ridge and is deflected upwards. As long as the glider pilot keeps the falling glider in air that is rising at a faster rate than the glider is falling, the glider will climb.
The Ideal Flying Site
Lift at any site is determined by wind velocity and the degree of slope in the hill. Slopes free of trees and buildings are best— where the wind flow is interrupted the least. The wind should be 10-20 mph and blowing straight into the slope.
Makes use of hot air bubbles that exist in the atmosphere. These are the same bubbles that make puffy cumulus clouds. As some air is heated more than others, the hot air ascends like an invisible hot air balloon. A soaring pilot keeps their glider in the rising column of air as it ascends to great heights.
The Ideal Flying Site
Dark surfaces such as parking lots, absorb heat from the sun, heating the air above. This creates the thermal, or the rising columns of air that lift aircraft. Nearby fields provide soft places to take off and land.
Makes use of a difference in wind speed over terrain to gain energy. It is a more complex process, but it is possible to extract tremendous energy from the atmosphere using this approach. Momentum is gained as the glider moves between the still air near the ground and moving air that is pushed over the edge of a ridge.
The Ideal Flying Site
A ridge with a leeward side accompanied by a bowl is ideal, as the defined boundary line between the fast moving wind and slowing moving ground air is necessary for dynamic soaring.
Membership with the AMA connects you with local clubs and flying sites where you could meet your next instructor. It also allows you to compete in nationwide events, disseminates current information on the status of model aviation and provides flying insurance.