Swashplate levelling

The swashplate is the heart of a collective pitch helicopter's control system. If it isn't level, or the servos aren't set correctly, the helicopter will drift, need lots of trim and never fly quite right. Getting it right takes half an hour and makes a real difference.

How the swashplate works is explained in how an RC helicopter works. This guide is the practical setup.

What you need

• A swashplate levelling tool for your helicopter's shaft size (optional but recommended).
• A pitch gauge.
• Ball-link pliers.
• The flybarless unit's setup app, menu or programming box.

See essential RC helicopter tools.

Step 1: put the flybarless unit in setup mode

Follow the unit's manual to enter servo setup. Most units hold the servos at their centre position and let you adjust each one. Set the transmitter's collective stick to centre (with a straight pitch curve) and check there are no trims or sub-trims in the transmitter.

Step 2: servo arms at 90 degrees

Each servo arm should sit exactly at 90 degrees to the servo body (or to the pushrod, depending on the manual) at centre. Use the closest spline position, then fine-tune with the unit's servo centre setting rather than transmitter sub-trim.

Step 3: level the swashplate

Adjust the pushrod lengths between the servos and the swashplate so that:

• The swashplate is level fore-aft and side to side.
• It sits at roughly mid-height on its travel, so it has equal room to go up and down.

With a levelling tool, the tool sits flat on the swashplate when it's level. Without one, measure each ball's height from the frame and make them equal.

Step 4: zero pitch

Fit the main blades (or use a pitch gauge on the grips). With the swashplate level at mid-stick, adjust the links between the swashplate and the blade grips until both blades are at zero pitch. Check both blades read the same.

Step 5: cyclic and collective limits

Follow the unit's manual to set:

• Cyclic travel: many units ask you to set a specific reference cyclic pitch value; makes differ, so use the figure your manual gives.
• Collective range: a typical sport setup is about ±10 to 12 degrees; check your helicopter's manual.
• Swashplate limits: so the servos never bind at the extremes.

Step 6: check directions

Move each stick and check the swashplate moves the right way. Then, with the motor disabled, tilt the helicopter by hand and check the unit corrects the opposite way. See gyros and flybarless units.

After setup

Fly gently, then check tracking: see blade tracking and balancing. Recheck the swashplate after any crash, because servo arms and links move. Back to the RC helicopters hub.