RCSD-2012-11 - RC Soaring Digest

• Weight of all elements and associated location in space and
inertia
• Profile(s) data (Camber, thickness and position in chord of
such…).
• Tail volume
• Center of gravity
• …
Aerodynamic characteristics are the consequences of such
physical definitions on plane behavior:
• Gliding ratio and speed associated
• Minimum sinking rate and speed associated
• Speed polar (Vz/Vx)
• Yawing, rolling, pitching moment
• Yawing, rolling pitching dynamic behavior (frequencies and
damping factors)
• …
Some of such parameters are real parameters, others are the
consequence of a conjunction of them and should be rejected.
We then need to have a clear picture and analyze everything.
So let’s look at the physical parameters that allow the accurate
aerodynamic characteristic behaviors that comply with our
classification and air conditions.
In reality, we will do the reverse:
For each flight phase, we have to determine and optimize the
aerodynamic characteristic that fulfills our classification and
find the associated physical characteristics that comply with it.
Altitude gain in lift
In order to optimize altitude gain in a thermal, we must first
study the thermals - their size, location, altitude...
Figure 3: A thermal can be modeled with few sinus functions.
Realistic? Let say this is not so stupid. That’s a start of the
understanding.
In Western Europe, most of the thermals are quite narrow at low
altitude. Let’s say that typically, the lifting air has a diameter of
20m at 50m altitude. This will then be a reference for our plane
design.
Their location and density in the field depends upon the field
itself - humidity, temperature difference, sun… Nothing to say
for the plane except that in some cases you might require going
far away to find them (so big plane, easy to fly). (See Figure 3)
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