NORTHERN IRELAND MODEL SOARING ASSOCIATION
(NIMSA)
NAVIGATION
Thermal Soaring
Thermal soaring relies on the differential heating of the air to provide lift and keep the glider in the air. Gliders are always falling out of the sky relative to the air they are flying in. If the air is static ie not rising or sinking the glider will be falling. In rising air (a THERMAL) the glider will still be falling, but if the air rises faster than the gliders descent rate, the glider will appear to rise relative to the ground. It is this rising air or thermal which keeps our planes aloft.
First however, we have to get the glider in to the air or launch it. There are 3 main methods for pure gliders:
There is one other method, the ELECTRIC SOARER, which I will deal with separately
A bungee consists of 30m of elastic shockcord or surgical tubing, attached to 120m of 50kg breaking strain fishing line. This is securely pegged to the ground at the elastic end, the other end being attached to the glider. The bungee is then stretched and the glider released. The stored energy in the bungee catapults the model to approx. 150m
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A winch is a powered drum with line leading out to a pulley at about 150m and back to the start where the pilot hooks it up to to the glider. A foot switch controls the winch and the plane is basically hauled in to the air.
Click the picture for a short video of winch launching from three perspectives
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| Watching the Launch (0.5Mb) | Looking backwards from the model (8 Mb) | Looking sideways from the model (1.8 Mb) |
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This is fairly self explanatory. A runner tows the glider in to the air.
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Thermal soaring models are lightly built using either balsa wood and foam or in the case of the modern competition aircraft they are fully moulded from fibreglass and carbon fibre. The lighter the aircraft, the more sensitive it is to lift and the longer it will stay aloft in even light thermals.
A selection of sports soaring models
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Any of these would be a good beginners model. It really depends on whether you want to build and fly, or just fly. In the latter case the ARTF or EPP models are very quick to get in the air and you get an almost guaranteed airframe.
Two Competition Models
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