Draganfly DraganFlyer V Ti, Manual

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18
How the Draganflyer Flies
continued
The Power System
This set of components is located on the horizontal circuit board and is essentially a set of 4 speed
controllers – one for each of the 4 motors. The most obvious components are the large square
devices located near the rear of the circuit board called FET transistors. FET means Field Effect
Transistors. These devices may be thought of as an electronic valve. There are 3 wires on each FET.
Two of the wires supply voltage to its motor, while the third wire (the trigger) is how the “valve” is
opened. Apply a small voltage, the valve opens a little and the motors start to turn. Apply a little
more voltage, and the motor turns faster still. Now just imagine that the FET is responding to your
raising and lowering of the throttle stick on the transmitter (via the radio receiver) and you now have
a grasp of just how the speed control works.
The wizardry in my opinion is how, by applying certain aspects of physics, the Draganflyer is con-
trolled. Let me give you an example. When something turns, in this case a propeller, a force is gen-
erated by the motor called “Torque”. The propeller wants to turn one way and the motor, the other
way. I am referring to Newton’s law that states that a force in one direction will produce the same
force in the opposite direction. Another force caused by uneven thrust of the propellers at differing
attitudes, is known as “P factor.”.
Conventional helicopters overcome these forces by using a tail rotor. As the main rotor blades are
turning via the engine, the opposing force is trying to turn the helicopter’s body in the opposite
direction. The tail rotor has a variable pitch mechanism that simply pushes more (or less as the case
may be) air and produces more linear thrust that offsets the effect of torque and “P factor”. Without
a tail rotor, a conventional helicopter’s body would spin out of control. To actually cause the heli-
copter’s body to turn (or pirouette) the pilot either increases tail rotor pitch or decreases tail rotor
pitch depending upon which way the turn is to be initiated.
In the case of the Draganflyer, the exact same forces apply. The speed controller is designed to
match the front and back, left and right motor-rotor speeds to be exactly the same. But the
Draganflyer rotates the left and right motor-rotors in the opposite direction from the front and back
motor-rotors. This, in effect neutralizes the torque and “P factor” allowing the Draganflyer to hover
without spinning out of control.
So what happens when you push the right transmitter stick to the right or left as you would in a turn?
Simple, this is called Roll. The Draganflyer’s electronic brain receives the signal through the remote
control receiver. The signal received tells the motor controller to send more power to the left motor-
rotor and simultaneously reduce the power to the right motor-rotor by the same amount. This caus-
es the Draganflyer to maintain altitude (total thrust has not changed) but to tilt up on the left side
and thus begin a right turn. The exact same thing happens, albeit in the opposite direction when the
transmitter stick is pushed to the left.
When the right transmitter stick is pushed forward or backward for a Pitch control (either nose up
or nose down) a similar series of commands are given to the front and rear motor-rotors. Lastly,
when the left transmitter stick is pushed to the right or to the left, simulating “rudder” on a conven-
tional helicopter, the Draganflyer’s electronic circuit responds by increasing (or decreasing) the
front and back motor-rotors opposite from the left and right motor-rotors. This in effect upsets the
torque and “P factor” balance of the aircraft and the machine begins to pirouette in response to
whichever direction the left transmitter stick is pushed.
Kept in either left or right pirouette, the little machine can get a wicked pirouette going that will
make your head spin just watching it!
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