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It's Jacob again and this video wraps up my "Basics" playlist by combining all the aerodynamic factors into 1 video. That said, hopefully you've watched the previous videos leading up to this one because I use this video to tie everything together.

So let's get started.. for simplicity I've broken down the takeoff process into 3 stages: Stationary Hover, Transition, and Forward Flight. During the Stationary Hover phase the rotor system has zero airspeed and is operating in its own rotorwash / wing tip vortices. This disturbed air causes the rotor system to be less efficient and require more power to sustain lift. As the helicopter moves forward, the rotor system is affected by Dissymmetry of Lift where the advancing side of the rotor creates more Lift than the retreating side. Gyroscopic Precession causes this to manifest as a pitch up tendency. Also during the transition phase, Transverse Flow affect takes places between 10-20 knots. This is the unequal Lift between the forward half and aft half of the rotor disk. Gyroscopic Precession causes this effect to manifest as a right roll. Dissymmetry of Lift, Transverse Flow, and Gyroscopic Precession cause the Transition stage to have a pitch up/ right roll. As the helicopter outruns its vortices and transitions through Effective Translational Lift, the entire rotor system is more efficient and creates more Lift. Dissymmetry of Lift is still present here and causes a nose up tendency in forward flight that can be counteracted by forward Cyclic inputs.

Simply said, stationary hovering requires more power than forward flight. And as a helicopter transitions into forward flight it will pitch up and roll right until it reaches ETL airspeeds. The reverse is true for landing. The rotor goes from high efficiency/ low power requirement to low efficiency / high power requirement with a right roll as you slow below ETL.

Once again, thanks for watching. Hit like and comment below if you enjoyed the video.

Here are the links to the first 6 videos that build into this one:
Dissymmetry of Lift (   • Dissymmetry of Lift in Helicopters  )
Compensation for Dissymmetry of Lift (   • Compensation for Dissymmetry of Lift ...  )
Gyroscopic Precession (   • Gyroscopic Precession in Helicopters  )
Transverse Flow Effect (   • Transverse Flow Effect in Helicopters  )
Airflow at a Hover (   • Airflow at a Hover in Helicopters  )
Effective Translational Lift (   • Effective Translational Lift (ETL) in...  )

If you're just getting started and want more information, pictures, and more explanations, I'd recommend reading the Rotorcraft Flying Handbook - http://amzn.to/2ifPlnZ

If you've already got a basic understanding, and want to further your professional helicopter education with advanced helicopter concepts, I'd recommend reading Cyclic and Collective, by Shawn Coyle - http://amzn.to/2ifQGLx