AG-1 - Las Vegas - N15LU

Steve_UK

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I'm not a pilot but have been lucky enough to fly in Mi-24 Hind, Mi-2, Mi-17, Lynx HAS3, Gliders, GA
Todays FAA ASIAS tells us on 18-12-17

GYRO COPTER BLADE AND PROP STRIKE ON TAXIWAY, LAS VEGAS NV
 
I never thought about this as I taxi with the rotor fore and aft, but can the wind blow the rotor aft enough to contact the prop even if its not turning.

I don't know if that's what happened here but it something to think about.
 
Many rotors can strike both the Prop and the Vertical Tail with the stick fully aft and the blade at the Aft Teeter Stop.
It takes Both situations to make it happen.
If the Rotor has sufficiently speed it will not approach the teeter stops.
If the Stick is held forward it can not teeter far enough to hit anything.

Remember...
If the Rotor is not turning at pre-rotation speed.the stick needs to be held forward at all times.

The Auto-Gyro products reverse pressurize the Pitch Trim Cylinder whenever the Rotor Brake is engaged.
This forces the Stik to the full forward position when the Rotor is in Brake Mode.

It is Bad Form to take your hand off the stick while Taxiing.
You should hold it Forward and Centered whenever the Engine is running.
 
Your right Uncle Willie the stick would have to be in the aft position,I was taught to always keep your hand on the stick and hold forward pressure when taxing.
 
Another outstanding design quality! With the stick full aft and no blade flapping, Sport Copter and Magni have a non-interference designs where the rotor will not contact the tail or prop. (I'll throw in Air Command and RFD as well). Pilots should not be put in the situation to compensate for a bad design. These design flaws are safety and cost ramifications to ownership.
As I stated in another thread, we can add this "feature" to the list! (in no particular order)
*Gyroplane design that allows rotor angle in a non-flapping scenario to impact the prop or tail.
*forward canting non-castoring nose wheels
*ADs to exclude rotor G forces and beyond 60 degree banks (characterized by extruded rotors)
*Structural integrity of the aircraft comprised of stainless steel that is not used in other areas of aviation construction. (ADs on weld cracking)

These features are starting to impact the public's view of gyroplanes as accidents and costs mount.
 
Every gyroplane rotor I have flown will hit the tail or the prop if I leave the stick full aft below eighty rotor rpm in windy conditions.

I have flown Magnis and Dominators.

Just stand behind the gyroplane and see how little force it takes to pull the rotor blade down into something with the cyclic full aft.

Every instructor I have with flown with taught me to keep the cyclic full forward when the rotor is slow.
 
Any rotor on any gyroplane when not spooled up enough that I have ever seen including Magni, RFD etc. can touch the prop and rudder. I doon't know what you guys are talking about that Magni or RFD doesn't do it. They sure do. If you flap the rotor blades, you can expect chopping of the prop or rudder. AG-1 when taxiing should be in BRAKE mode which forces stick forward via pneumatic pressure. This is purely pilot error. You cannot make a design of an aircraft idiot proof.
 
You guys are right its not a design flaw,its a pilot flaw,every instructor on the planet teachs to keep the stick forward for safety when taxing or at a low rotor speed.
 
NOT a design failure. Holding the stick forward during taxi is one of many things a pilot must do to not break his gyro or kill himself. If you are not prepared to assume the responsibility for being a pilot then don't become one.
Rob
 
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.
 
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.
 
One feature I like about my Sport Copter rotorhead's air-trim system is that I can taxi after landing with the teeter bar pushed forward to the stop.
This is welcome on very gusty days when the rotor is not prone to slow down as easily.

Regards, Kolibri
 
I have watched that video before and have had a divergent definition of rotor flap and a different procedure when rotor flap in observed.

This is exactly why I said to Not Listen to the Audio! ... Now that you opened that can of worms... :rolleyes:

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.

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.

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.

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. :cool:
 
Uncle Willie;n1128185 said:
This is exactly why I said to Not Listen to the Audio! ... Now that you opened that can of worms... :rolleyes:



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. :cool:

We have a divergence of opinion Bill.

I feel I have had a rotor flap event without hitting the teeter stops.

In my opinion the disk angle is often part of a rotor flap event and it is best to get the cyclic full forward and get stopped as soon as possible.

I feel getting the cyclic full forward makes it less likely for a rotor blade to hit something.

In my opinion at the onset of rotor flap the rotor begins to slow rapidly and simply reducing power (slowing down) is not enough.

I have nursed a flapping rotor up to speed and although it was successful I feel it was a poor aviation decision.

I have not had success with telling people to just watch and not listen. I had seen and heard the video previously.

I felt Desmon was just redefining what he felt was rotor flap so I thought I would share my definition of what I felt was commonly referred to as gyroplane rotor flap.

I have flown with Desmon and in my opinion he flies well and is knowledgeable about aviation.
 
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. :eek: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?

The problem I have with the video is where it is implied that the flapping originates at the Rotor Tips.
He induces an oscillation in the rotor that causes the Both Rotor Tips to flap Up and DOwn in unison and states that the flapping is similar to the wings of a bird instead of the Forward Rotor Tip flexing Upwards while the Rear Tip Flexes Down.
What is never explained is the source of the energy causing the oscillations.
The analogy with extension cord does not make any sense to me.

I was going to disagree with the FAA's Rotorcraft Flying Handbook, Page 20-1, about Rotor Flapping but I find that I am in agreement with them.

During Pre-Rotation into a brisk headwind, it is not uncommon to feel a Teeter Stop Bump or two on the first few revolutions of the Rotor. ( A Mini-Flap!)
This stops very quickly as the rotor gains speed. It is mostly a non-event as the stick is being held forward at this point.
 
Did this happen after landing or taxing to take Off? I don’t spin up until lined up to take off. It doesn’t take much time and traffic can wait.
 
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. :eek: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?

Unless there is more trim than I like to use there is some pressure involved on the cyclic as the rotor comes up to speed and I bring it forward to balance on the mains.

I have felt normal pulsing of a two blade semi rigid rotor become stronger indicating to me I am not managing my airspeed and rotor rpm well.

I felt it several times in Cavalons when the clutch on the pre-rotator failed to fully engage and I was trying to nurse the blades up from around 160 rotor rpm and a few times in The Predator that only has a one hundred rotor rpm pre-rotator.

It is usually in gusty conditions and I feel the best thing to do is get the cyclic all the way forward and stop the aircraft.

It has been my observation that rotor can go from a slightly divergent tip path to enough divergence to hit something very quickly.
 
I find the topic of "Blade Flap" is poorly explained in the Rotorcraft Flying Handbook and overly confusing. It would have been fine if it stopped with:

"Unequal lift acting on the advancing and retreating blades can cause the blades to teeter to the maximum allowed by the rotor head design. The blades then hit the teeter stops, creating a vibration that may be felt in the cyclic control."

In short, it is Dis-symmetry of lift which causes the blades to flap to the limits. And there are two components to the dis-symmetry: The speed of the blade to the relative wind, and the angle of attack.

Certainly one way to experience "blada flap" is a slow rotor on the ground, where movement or wind can cause the blade to flap to limits. This is frequently observed in the early stage of pre-rotation or when the rotor is slowing down to a stop. Having the stick forward is important for two reasons: 1) When forward and at the teetering stops, the blade should not impact the tail or propeller. and 2) the stick forward reduces the amount of lift the advancing blade produces, which reduces the dis-symmetry of lift (so you don't hit the stops).

Blade flap/mast bumping can also occur at high speeds as well (like take off with a slow rotor). Reducing the power will reduce the speed, and hence the relative wind difference. Pushing the stick forward will reduce the angle of attack (and amount of lift) on the advancing blade.
 
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