RE: Jetmach floating on landing
I now have time to explain the above a little deeper...</p>
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Consider your elevator stick on your Transmitter... it is spring loaded to return to centre...</p>
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Lets call this centre position 0% deflection..</p>
Lets call Full back deflection (UP Elevator) 100% deflection</p>
Full forward would then be -100% deflection But we can forget about that for this discussion..</p>
Exact numbers will change for each aircraft type but the theory is the same for all...</p>
If your aircraft is trimmed to fly level at full throttle with 0% elevator deflection - The angle of attack of the main wing is approximately 2 to 3 degrees in normal level flight..</p>
The more you deflect your elevator, the greater the angle of attack on the main wing..</p>
Assume that 100% deflection gives you 20 degrees angle of attack..</p>
It follows that 50% deflection will give you 11 degrees (half way between 2 degrees and 20 degrees)</p>
Any aerodynamic text book will tell you that an average aerofoil will stall at 16 degrees angle of attack</p>
at 15 degrees it will be unstalled and at 16 or more it will be stalled..</p>
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In this example, you would reach 16 degrees with about 78% deflection of the elevator joystick</p>
So regardless of speed or attitude, if you don't pull more than 78% elevator, your aircraft will not stall..</p>
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Again, regardless of speed or attitude, pulling more than 78% elevator you WILL stall.</p>
:When landing a real aircraft you aim to approach at 1.3 xthe 1 g stall speed in the landing configuration.</p>
In this example.. this would require an angle of attack approximately 12-13 degrees during the stabilised landing approach (disregarding flaps)</p>
Which means, flying a stable final approach at the correct speed, you should be holding steady back elevator of about 55 to 60% deflection..</p>
If this amount of deflection produces a pitch up or zoom climb then you are approaching way too fast..</p>
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These figures are just for explanation purposes and any number of factors can change the actual figures / stick position for the stall on your aircraft...</p>
EG, dual rates, how much elevator deflection you have set up with your servos, C of G changes etc etc.. but the theory is solid...</p>
For your aircraft there will be an elevator position that produces the stall.. without changing your rigging or CG significantly this position will remain the same..</p>
It will change slightly if your aircraft has flaps, but again there will be a new position that causes the stall when flaps are extended and this again will be constant for a constant flap position..</p>
Its almost impossible to get a feel for the stall speed with an RC aircraft because you are not in the aircraft and you don't have an airspeed indicator, temperature and wind can change the appearance of actual speed anyway.</p>
But it is very easy to get a feel for the stick position of the elevator when your aircraft stalls, and once you understand this concept and develop the muscle memory of knowing exactly where your aircraft stalls you will be able to fly it much more accurately during tight aerobatic manoeuvres and during landing approaches.</p>
I hope my humble attempts to explain this in text will help, usually this is something best demonstrated practically..</p>
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