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Making the tail rotor ¡@ |
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making the main body
making the cyclic control system ¡@ an introduction to electronic components building an airborne video system ¡@ |
¡@ | The tail rotor consists of a motor, tail
blades, tail shaft holding tube and a blade holder. The tail control is
managed by changing the RPM of the tail motor. The drawback of this kind
of control system is its sluggish response as the rotor pitch is fixed.
However, it makes the whole design much more simpler and reduces a lot of
weight.
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¡@ In an ordinary R/C helicopter, the gyro work together with the tail servo. However, in this design, the gyro has to work together with the ESC (electronic speed controller). Will this work??? At the beginning, I try this with an ordinary gyro ( the large one for the gas helicopter). The result is really bad that the RPM of the tail rotor changes from time to time despite the helicopter is standing on the table. I buy a micro-gyro later which is specially designed for small electric helicopters and to my surprise this works great.
¡@ ¡@ ¡@ Here is the measurement of the tail blade. It can be shaped easily from a 2mm thick balsa. the tail blades make an angle of ~9¢Xon the blade holder ¡@ ¡@
The photo shows all the things that the tail part consists. The two balsa blades are hold by a hardwood holder which helps to give a fixed tail pitch. It is then secured on the gearwheel by 2 screws. The motor is simply glued on the tail boom by epoxy adhesive and the tail shaft holding tube with the same way on the motor. The tail blade is made of balsa. They are covered with heat shrink tube in order to reduce the friction between the blade and the air. The pitch and the weight of the two blades must be exactly the same. Tests must be performed to ensure that no vibration occur. ¡@ ¡@ |
Ben Hui - web master 2002 |
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