A Quick and Dirty Guide to Coaxial Rotors

A quick setup guide to building a coaxial rotor helicopter using the stock gyro.

Introduction

Building a helicopter can be a frustrating process for new players. This guide will demonstrate how to configure a very basic coaxial helicopter.

Step 1) Build your helicopter

I am not going to offer many details here. I went with a simple design for this demonstration, consisting of a medium motor, batteries, a chair, a gyro, and the two rotors. There are two very important things to keep in mind as you are building:

a) Place your bottom rotor at the default rotation, Forward/Right Positive according to the arrows near the top of the rotor. Press U to flip the rotor across the x-axis, and then place your top rotor. It should be in a Forward/Left Positive position. Set both rotors to Neutral position.

b) Try to keep your center of gravity directly below your rotors. This will ensure stable flight.

Step 2) Add Needed Components

To your helicopter, add the following components and logical connections:

a) A Throttle component with output connected to your engine or motor's Throttle node
b) A Numerical Inverter controller with output connected to the Roll node of the top rotor
c) An Addition controller with output connected to the Collective node of the top rotor
d) A Subtraction controller with output connected to the Collective node of the bottom rotor

Step 3) Wire Your Chair to the Gyro and Throttle

Connect your pilot seat's logical nodes to the gyro's nodes as follows with the appropriate (Settings):

a) W/S(Reset) - Pitch
b) A/D(Reset) - Yaw
c) Up/Down(Reset) - Up/Down
d) Left/Right(Reset) - Roll
e) Hotkey 2(Toggle) - Auto-Hover

Connect your chair to the Throttle component as follows:

a) Hotkey 3(Push) - Throttle Down
b) Hotkey 4(Push) - Throttle Up

Set the Sensitivity on your Throttle component to 10%.

Step 4) Connect the Gyro

Connect your gyro's logical output nodes as follows:

a) Stabilized Pitch - Connect to the Pitch node of both rotors
b) Stabilized Yaw - Connect to the B nodes of the Addition and Subtraction controllers
c) Stabilized Up/Down - Connect to the A nodes of the Addition and Subtraction controllers
d) Stabilized Roll - Connect to the Roll node of the bottom rotor and the input of the Numerical Inverter controller

Step 5) Check your connections

Double-check electrical hookups. Make sure your throttle and gyro are connected to electrical. Check logical connections and pilot seat settings.

Step 6) Take Flight

You are ready to fly.

To take off, throttle up some using Hotkey 4 and then tap Up arrow until you start to lift off. My craft only needed about 15% throttle to take off. Use Down arrow once airborne to settle into a hover.

To fly, use W/S to pitch forward slowly. A/D will rotate your craft, Left/Right arrows will roll your craft. Hotkey 2 will flatten out your craft.

And that's it. You now have a working model of a coaxial helicopter.

Yes, I am terrible at flying helicopters.

Below is a working version based on the above instructions. It's a simple electrical equipment helicopter with about 20 minutes of run-time.

https://steamcommunity.com/sharedfiles/filedetails/?id=2422043866

[Aven]

@Rexboy909: Yes, it would, but the goal of this guide is approach-ability by using stock parts. You can absolutely build a single microcontroller that bridges the chair controls and gyro outputs with the rotors, but that is beyond the scope of this guide.

[Rexboy909]

I think it would be pretty easy to make the logic into a microcontroller

[Aven]

@tekelidook: Not sure on that one. Double check your rotor placement and center of gravity. You can post it to the workshop as well and I can take a look.

[tekelidook]

I am having a weird problem where shortly after takeoff, the helicopter starts twitching violently back and forth in pitch, which escalates until it flips over. What am I doing wrong?

[Abyss]

I missed that, thanks

[Aven]

@Adventure888: They are connected to the collective nodes of their respective rotors: a+b goes to the top rotor, a-b to the bottom. It's listed in Step 2, letters c) and d).

[Abyss]

what do you do with the a + b and a - b nodes?

[SeeFights]

Never mind i had a trim active : )

[SeeFights]

I followed this and when im flying the helicopter tends to roll to the left when flying and if it tilts too far itll roll and spin and freak out

[HappyHeatPump]

Thank you! This worked great.