Flight of slope

The flight slope , also called Soaring , or surf tunes , is a technique gliding without towing or winching or engine. When a valley breeze encounters a relief, it rises generating a dynamic updraft , which accumulates most of the time in the mountains with thermal updrafts . By staying in this very holding region, the gliding, a RC glider , glider , glider or gliding may remain in the air all the time will this dynamic.

Slope flight enthusiasts are accustomed to associating a slope, the particular flank of a relief with the wind that will generate the updraft . For example, this or that slope will be usable and used only in the presence of a well oriented wind. While this effect is not very sensitive with a glider that can move over great distances, a glider smaller as a radiocontrolled glider will be very attentive to it: the amateurs of model airplanes choose the place of their exploits according to the wind dominant of the day.


Practicing the radiocontrolled glider in slope flight is also pleasant thanks to the very small means used to put the aircraft in flight. Most often, the operator holding the remote control in one hand throws the glider of the other by facing the wind. Almost all other aeromodelling practices involve a more complex takeoff procedure (motorized or towed).

The glider should not be thrown up, but rather down (and flat), so that it can gain speed. Throwing it up would slow it down, it would land then, and being only a few meters between it and the ground, the model would collapse.

The remainder of the flight consists of looking for ascents , whether they are thermal (due to the elevation of warm air) or mechanical (elevation of air masses because of the slope), to increase the altitude of the glider , and the duration of the flight. When one of these currents is present, the aircraft alone takes altitude, or tilts if only one wing is captured by the current. It is then necessary to “spiral” the glider, so that it remains in the area where the air rises, and that it is driven too.

The flight out of updrafts must be economical, because the maneuvering control surfaces are losing speed, so the altitude.

A risk for a model runner on a slope is to put his glider “the hole”, that is to say, to lose too much altitude, and have to land below, in the valley. The glider can of course be raised to a sufficient altitude, but if the ascending currents decrease (for example with a change of weather), the chances of landing in a nearby area diminish accordingly. Once “in the hole”, the glider and the landing zone are then very far from each other and not very visible, and the glider’s altitude estimate becomes difficult, and it can be damaged at landing.

Climbing speed

A simplified 2-dimensional model derived from the orographic wave model is considered . Is{\ displaystyle N = {\ sqrt {{g \ over \ theta} {\ partial \ theta \ over \ partial z}}}}the frequency of Brunt-Väisälä (of the order of 10¯²), ie U the wind speed, or h (x)the height of the ground at the point x , the rate of climb can then be modeled by the following approximate formula:

{\ displaystyle w (x, z) \ simeq Uh ‘(x) cos \ left ({Nz \ over U} \ right)} .

It can be seen that the rate of climb decreases with altitude. This formula does not take into account the turbulence that could form in the case where the slope is a cliff.

Activities practiced in slope flight

  • The gliding
  • the aerobatic
  • The fight

There is a category of special gliders intended for the flight of slope, it is the PSS ( Powered Scale Soaring ) which are mock – ups or half-mock-ups of motorized airplane or reaction which are used without engine in the moderately strong dynamics to very strong.


  • List of Slope Flight Sites in France  [ archive ]
  • Slope flight sites in France and around the world  [ archive ]

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