Thermal Duration Soaring

What is it?

Themals are naturally occuring rising columns of warm air. The goal of thermal duration soaring is to find these invisible sources of lift and fly a sailplane within them long enough so stay airborne. Since a thermal cannot be seen, one has to develop skills in detecting subtle changes in the environment, which can signal the presence of thermal activity. This can be a great challenge for both the novice and skilled pilot alike. Successfully finding a thermal and soaring up into the sky is also one of the most rewarding experiences in the hobby!

In order to start searching for thermal lift one has to first get their sailplane into the air. Typically this is done with what is know as a hi-start or a winch. A hi-start is consists of a length of surgical tubing and nylon line that is stretched out and released with a sailplane on the end of the line. As the surgical tubing contracts the model moves forward and jumps up several hundred feet into into the air. A winch is a more complicated launch device and there are many different designs in use. All of them include a spool with at least 600' (or more) of braided nylon or monofiliment line which is connected to a 12V motor and operated with a foot pedal. The winch is placed at the flight line and then the line is pulled far upwind, through a turnaround and then back to the winch again where it is connected to the tow hook on the model. As the operator steps on the pedal the winch motor starts up and begins reeling in line. This pulls the model forward and up into the air in a similar fashion to the hi-start. The winch is much more expensive, more complicated, requiring more maintenance and time to set up. It also offers much more control, power, and the ability to launch larger models higher than the the hi-start.

A fairly large and open field is required to set up and use a hi-start or winch. For that reason much of our thermal duration flying is done on a sod farm. Folks wishing to fly thermal duration on a smaller field such as a park may find that electric powered sailplanes are preferred.

Contests

MRCSS has traditionally had one thermal duration flying contest per month from May through September. The contest format is up to the contest director and it will vary somewhat from month to month. Like almost all thermal duration contests, ours include two components. They involve flying a series of timed flights with each one requiring a precision landing of some sort. The flights may include rounds of 5, 7, 10, 12 and 15 minutes. A point is scored for each second of flight time up to the goal for the round. Points may be subtracted for each second of flight beyond the goal. Additional points are scored for landing within 1.5 or 3 meters of a target.

Almost any kind of sailplane is eligible to fly in our contests, and tasks vary somewhat depending upon what class your model falls into. We usually have people fly in one of the following classes:

  • 2M (up to 2-meter wingspan)
  • RES (rudder-elevator-spoiler for controls)
  • Unlimited (anything else)

Pilots compete against others for placement within their class and an overall placement is determined for the contest with LSF points awarded when possible.

The League of Silent Flight

The League of Silent Flight (LSF) is a special interest group to the AMA for soaring. The LSF was established by a group of R/C sailplane modelers in 1969 to provide a collective identification for radio control sailplane enthusiasts. The LSF quickly became very popular and has since grown to a membership of over 7,500 modelers. The non-profit LSF fosters and supports all phases of both sporting and competition activity for model sailplanes and encourages the advancement of model aeronautics and related aspects of RC soaring.

Many MRCSS members who fly thermal duration are participating in the LSF Soaring Accomplishments Program. This program challenges the pilot to increase their flying skills in both the area of thermal duration and slope soaring. Visit the LSF web site to learn more and consider joining us as we work towards becoming better pilots.

Popular Models

Following are two lists of models. One includes those which are especially well suited to new modelers, while the other lists some of todays most popular models that are flown by the advanced or competitve pilot.

Beginner Models

Advanced Models

Wood

Foam / Electric

Composite

 

Thermal 1
Thermal 2
Thermal 3
Thermal 4

Thermal photo galleries: