Before you fly a Single Rotor Helicopter
Single rotor heli's are more complex than co-axial heli's and require more tuning and adjustment to fly well. You should carefully inspect one every time you fly it. Small faults that a co-axial helicopter might fly with will throw a single-rotor machine too far out of balance to fly.
If you are flying a helicopter that you bought used do not assume that any part of it is correctly assembled or adjusted! Check everything.
Pre-flight Checklist
1. Broken parts - check the frame, skids, tail boom, mechanical moving parts. Don't fly with broken parts. Repair them or replace them.
2. Main rotor blades - check for damage and make sure they are in balance. Don't fly with broken blades and don't attempt to repair main blades for this type of helicopter. Small abrasions or tears in the heat-shrink coating of balsa blades may be carefully taped down. If you do this, be sure no loose tape edge is facing the blades' direction of travel. Damage to wood blades' structure makes them unusable.
3. Flybar paddles - must be equidistant from the center of rotation and parallel to the flybar frame and each other. It is worth takingtime to get them right because the helicopter will fly much more accurately.
4. Control links - ball links and connectors from servos to the swash plate must be in place.
5. Tail rotor retainer - if the heli has a tail motor the tail rotor is kept on its shaft with a piece of tubing. The tubing must be pushed all the way towards the rotor so it will mate with the driven gear, which in turn will mesh with the pinion gear on the tail motor shaft.
6. Main motor pinion - the fit between the gear on the main motor and the main gear should not be too loose or too tight. Slowly rotate the main gear and check for play. Some main gears have low spots, and a small amount of play is all right as long as there is no play at the high spots.
7. Center of Gravity (CG) - with main blades straight and the flybar perpendicular to the fuselage, hold the heli by the flybar and look at it from the side. It should be level or very slightly nose-down. Move the battery forward or backward to adjust the CG.
8. Turn on the transmitter (Tx) with the antenna fully extended. Always turn on the transmitter first. This is important! If you plug in the flight battery without turning on the transmitter the main blades may start turning and the model can even take off by itself! If this happens you will not gain control before it crashes. After you turn on the Tx place it out of the way so you will not accidently hit the left stick while you are getting the helicopter ready to fly.
9. Plug in the flight battery on the helicopter. (The plastic 'JST' connector only allows you to plug the wires in the right way.) Wait for the LED (light-emitting diode) on the 4-in-1 in the helicopter's nose to stop flashing and show steady green.
If the LED keeps flashing the throttle stick may be raised. If it alternates between red and green the radio link is not established. Push the throttle down all the way. If the LED shows steady green you are good to go. If it keeps flashing or shows red you need to track down the cause. The radio crystal on the Tx or the receiver (Rx) in the model may not be seated. You can remove the crystals, see how they fit, and carefully re-insert them.
10. Slowly move the left stick upward to gradually spin up the main blades to 30% or 40% power. Do the blades turn smoothly or is there vibration? A bent rotor shaft can cause the heli to vibrate. So will damaged or broken rotor blades. If the tail swings insistently to the left or right the gyro settings may need to be adjusted.
11. Blade tracking (CP heli's) - both main rotor blades should fly in the same horizontal plane. You can check them before taking off by spinning them to 40% power and looking at them edge-on. Stay at least a yard away from the ends of the blades. If you see 'two blades' they are out of track and need to be adjusted, usually by means of the short links on the flybar frame. The other way to check tracking is to hover the helicopter at eye level. Distinguish the blades from each other with different colors of tape near the ends so when you change the length of a link you will remember which blade it affects.
If anything seems wrong you must find and cure the problem before flying.
12. If the main rotor turns smoothly, the heli doesn't shake or spin, and there is good power you are ready to take off.