The use of 2.4 GHz radio transmitters and receivers is now legal for use in competition CL stunt models. Legal uses of the 2.4 system are motor shutoff and landing gear retraction and extension. For me this is the preferred method. For one thing, if I get a prop strike on takeoff, or from something in the air (a bird for example) and break a blade, I can shut the motor (or in my case, motors...) off and save the model from damage from vibration. It also prevents the possibility of the motor or engine from vibrating loose and flying off the model and hitting someone. Landing gear retraction and extension can be done at the pilot's discretion. Easy peasy. The actual hardware doesn't weigh much at all, and is now very cost effective.
Another method of retraction and extension is via one of Will Hubin's timers. The timers can be used in IC applications to just retract and extend the gear. The needle valve adjustment time would not be a problem if the helper or pilot simply pushes the timer "go" button after having adjusted the needle valve. In electric there is no need to adjust the motor speed after starting, so the timer function is a no-brainer there.
Retracts pose other problems, however. Most applications (especially single engine/motor planes) have the gear retracting inward, like a P-51 for instance. That would be no problem if it were possible to lock the inboard end of the strut into the wheel well. Under "G" loads the strut may tend to "sag" out of the well in inside maneuvers. This will disturb the airfoil and affect the model's flight. The lighter wheels available these days tends to minimize this affect, but it is still there. I've found that retracting the main gear on my twin designs forward into the nacelles (or up next to the nacelles in the profile test bed ship...) and the nose gear rearward into the nose of the fuselage circumvents this problem.
Just some thoughts..
Bob Hunt
Topic: New Retractable Landing Gear System (Read 3554 times)