Uncle Willie;n1128168 said:This Video demonstrates the interference between the Rotor and the Tail when the stick is Aft with full Aft Teeter.
Keep in mind that the normal takeoff procedure uses Full Aft stick.
With the Rotor turning at sufficient speed, teeter is minimal and the tail strike does Not happen!
Notice at 0:30 in the Video where the Rotor Brake is released and the Rotor Head falls full aft.
At 1:40 the Rotor Brake is re-engaged and the Head return to the forward position.
It is best to watch this video without sound as the music is annoying and the dialog about Rotor Flap is dubious.
I have watched that video before and have had a divergent definition of rotor flap and a different procedure when rotor flap in observed.
My definition of rotor flap is when one or both blades stall on a two blade semi-rigid rotor tending to lead to divergent tip paths.
In my opinion, the cause is too much forward speed and back stick with too little rotor rpm.
In some cases this may lead to the retreating blade stalling and the advancing blade continuing to fly pushing the retreating blade rapidly down often into either the rudder or the propeller.
In my opinion when encountering rotor flap recognized by sharp quick movements in the cyclic the safest procedure is to get the cyclic forward and stop. In my experience simply reducing the power may not be enough to stop the flapping before some damage is done.
Uncle Willie;n1128185 said:This is exactly why I said to Not Listen to the Audio! ... Now that you opened that can of worms...
Rotor Flap is caused by too much forward speed and too little Rotor RPM.
The Teeter Angle hits the stops, most commonly with the stick Fully Aft, But not a requirement.
The Teeter stop strike causes the stick to be forced Aft. If it is already at the Aft Limit, the blades bend (Flap) and bad things happen.
In a Helicopter, this is called Mast Bumping.
We should be calling it Teeter Stop Bumping, but it is commonly called Flapping.
As seen in the video, it is possible to have a tail strike before the teeter stop limit is reached.
If the stick is positioned forward of the Aft Limit, the sharp quick Movements of the cyclic is the aft teeter stop being bumped and shoving the stick Aft.
As the cause is too High Airspeed with too Low Rotor RPM, the exit plan would be either to increase the Rotor RPM ( I don't know how that is accomplished!)
or reduce the airspeed. This means reducing the throttle without delay. (This, I know how to do!)
So. the way out of the predicament is to reduce Power, Slow Down, Wait for the Rotor RPM to increase, and then judiciously add the power back in.
The Slowing down part is often carried to the Stopping Point to give time for your Adrenaline to recover.
Steve_UK;n1128133 said:a news item on the owners website suggests the AG-1 had only recently moved to LV
http://www.luciaair.com/blog/index.php?id=as29xr63
Uncle Willie;n1128218 said:Hi, Vance,
The original discussion was about whether a stopped rotor could strike the Prop while Taxiing.
Bear in mind that the "Don't listen" request was done mostly Tongue in Cheek as I was trying to avoid going into a Flapping discussion.
But here we are. hwell:
It seems like we are 90% in agreement.
I agree that stick forward unloads the rotor and reduces the Teeter (Flapping) angle causing the flapping to cease.
And that the primary contributing factor is Excessive Airflow with insufficient Rotor speed.
I do not understand how you propose that the flapping is initiated without hitting the Teeter Stops.
What do you feel causes the Sharp Quick Movement of the Cyclic felt during a Flapping event?