Imagine you have whale2's Infernal robotics config and infernal robotics itself installed. You want to build a Helicopter to flex in forums, reddit and discord. Here's the guide of doing so!

Building the helicopter itself

• make sure RCS build aid is also installed.
• Drag a cockpit. Make Any "dry" structures(no fuel or consumables) you will Want(such as tail fins) . Don't add too much or it would be too heavy!

Engines

Procedual wings blades under FAR(which is the standard mod responsible for RO aerodynamics) do not work.

• Use Merlin 66 prop engine as it is the best-preforming engine on sea level in RO.
• NOW TURN ON MECHJEB AND SEE IF YOU NEED MORE THAN One (turn off cosine loss) Merlin 66.(at least 1.4 SLT is needed)
• Now move the engines where RCS build air shows no Torque.

Control

Now if you simulate the launch, it will just crash a few seconds later due to lost of control.

Alternatives

Why not just use rcs and remove the need of IR? It's because RCS need their separate fuel, which is really hard to deal with when your CoM is so sensitive. Also they have weak control in the atmosphere.

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Why not make thrust vectoring on engines, just like real helicopters controlling blade pitch? Because any robotics in ksp are soft, and they bend like wet noodles when a strong force is applied.

The standard

Just like stock ksp, we can use reaction wheels. Now you may ask:

isn't reaction wheels nerfed to death in RO?

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But you can make one yourself by using Infernal robotics. Grab 3 rotatorons, stick them on the center of mass, and attach a plate on each by procedual structures(the larger diameter the better, but see if you can fit those in you helicopter) . Now turn all rotatorons to control input mode and rotor mode(instead of the default manual and servo mode). Drag the pitch, yaw and roll control slider of the corresponding rotatorons. After some simulation and test, you can proceed to the next step.

Fuel

Add thick procedual wings to the Center of mass. Store Aviantion Gasoline in it. See if any torque is generated on full fuel and 0 fuel. If yes, adjust.

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You would roughly result in this kind of helicopter configuration. Make sure you have enough thrust to liftoff!