GAUI 200 SD torque tube conversion kit .. part .. 4 finally I did It correctly .. 👍😁 ..

This time I did not forget main shaft bearing ... 😁 ..
RC Helicopter Autorotation Explained
Autorotation (auto for short) is the method full size helicopters use to glide down safely and under control when there is a loss of power.
Our helicopter does have wings - they are called rotor blades. Rotor blades are simply rotating wings, and as long as they are rotating fast enough, they provide lift. The question is how to keep them rotating fast if there is no engine power?
You need two things to achieve this...
1. Autorotation Requires Collective Pitch
First - do you remember me talking about the other benefits of Collective Pitch in the Fixed Pitch or Collective Pitch section?
Well, here is one of those benefits.
When your engine quits, you immediately change the pitch angle of the main rotor blades from positive pitch to slightly negative pitch (assuming you are not inverted, when inverted, you do the opposite).
The whole idea behind this is to maintain rotor speed/energy as the heli descends and then as the helicopter nears the ground you change the collective pitch angle of the rotor blades back to positive. The kinetic energy built up in the rotor disc allows you enough power to stop your descent and make a soft landing.
This is actually quite tricky but once you do a few autorotaions, it can get pretty fun.
Having the right amount of negative pitch and positive pitch is very important; generally at least -3 degrees up to +12 degrees but it depends on your helicopter. Larger birds auto better than small ones because there is lots of blade area and rotor mass.
Auto rotations work much better if you have some forward speed providing "clean" air (also referred to as translational lift )
This is generally referred to as "glide path" or "glide slope" and a forward glide path of about 45 degrees provides a good slow descent rate at around -3 degrees collective while maintaining ample amounts of rotor energy.
The key to a successful autorotation is all in the timing and knowing when to slow your descent and forward speed by flaring with a rear cyclic command, applying positive collective pitch, and then leveling out the heli just before touch down with forward cyclic to land gently. All that without dissipating all the energy in the rotor before you land. Remember, you only get one shot at this. Boom strikes are common if you over-flare and lose most of your rotor energy before touching down.
This way, you can still come in with a little forward speed if you don't flare enough and "slide" out the landing. Sliding out an autorotation is far better than boom striking.
Performing an autorotation into a slight head wind is also much easier than trying it downwind so take that into consideration when setting up your approach. You generally want to be about 50 to 75 feet or so high when you hit your throttle hold.
The glide in phase of the autorotation should have the very slightest amount of nose down attitude to maintain that 45 degree glide slope.
In other words, if your heli is about 50 feet high, you should start the auto about 50 feet away from the spot you want to land. Remember, your glide path is going to be about 45 degrees so if you hit throttle hold as the heli is passing overhead right in front of you at 50 or so feet, it's going to be about 50 feet distance away from you when it touches down.
Blade grip tightness is pretty important as well. If the blades are too loose in the grips, they will lag excessively with all that positive collective pitch drag and rapidly decaying head speed during the landing.
This is heli size dependent of course, but the blades should be at least tight enough in the grips that they don't pivot downwards when the bird is held on edge and given a light shake. Blade mass also plays a roll. Most stock blades are fine but do stay away from super light rotor blades.
If you had fixed pitch or kept the rotor blades at a positive pitch angle, they would soon stall and stop rotating. Yup - the helicopter has now become an expensive rock. This is why autorotations rely on collective pitch.
2. Autorotation Requires One Way Drive Bearing/s
The second thing your helicopter needs to perform autorotations is a way to disconnect the main rotor shaft from the rest of the drive or gear assembly (the engine/motor and in some cases, the tail rotor).
Plus you don’t need the tail rotor spinning during an auto rotation since there is no more torque being developed with no power going to the main rotors.
That said, most aerobatic RC helicopters do keep the tail rotor spinning for yaw control during the auto. Keep in mind however, the more tail input you give, the more power you are robbing from the rotor disc so keep tail inputs small when first practicing.
With no engine noise, the only thing you can hear is the rotor slicing through the air. Hearing how the noise changes as the blades are changed from negative to positive pitch just before touch down.