Unloading of the rotor?

[BeefBear]

Okay, I'll play the part of the dumb guy ( yeh I know it fits me to a tee) and ask a question or two. *I read all the time about fixed wing guys intentionally pushing forward on the stick when trying to stabilise the gyro but in an engine out one I assume needs to get the stick forward *to maintain 55 knots or better for descent speed. *What's the difference here except maybe the size of the movement and the missing power? *Doesn't the rotor become sort of unloaded for a moment as you position yourself for downward travel?

Anyone who speaks in double dutch to me on this one can expect Iraq type terror tactics between their house and their favourite drinking hole!!!

Ted

[russ]

? Doesn't the rotor become sort of unloaded for a moment as you position yourself for downward travel?

Don't factually know this answer.........ata guess, YES........so what [ would be minimal ]
Do know that in normal flite, tossin it around etc,and wind shears etc,severe downdrafts etc..blades momentarily become unloaded..........does'nt cause any probs here

As to maintaining 55kts or better with engine out..........phew, damn quick, would expect most if not all gyros would be better at around 40 kts glide speed.

Actually all pilots should experiment with THEIR gyro, to determine THEIR best glide ....distance .....speed rate.....could save em one day

[BeefBear]

This "what was a Raf" gyro of Waddles needed 55 knots when it was in the approach attitude

[rotor]

Ted,

I think the difference is that the fixed wing guy is trying to catch up with the gyro and is one step behind and the action of forward stick in an engine out is a direct input you initiate whilst maintaining control.

[BeefBear]

You are probably right. Its the " how far behind the aircraft" factor once again.

[GyRoss]

Ted
When the engine stops, your airspeed is generally going to drop off very fast.
As airspeed decreases, the angle of the airflow relative to the rotor disk increases.

With the increased angle of the airflow it is more difficult for the pilot to induce a negative airflow thru the rotor disk.

The other way to look at it is to consider a gyro travelling very fast, and thus with a very small angle between the rotor disk and the relative airflow. In this situation only a small disturbance( from pilot or atmospheric) is required to induce negative airflow thru the rotor.


Ross B

[BeefBear]

That's probably very true too ross.

[russ]

Scinario.................been flyin, get back it's blowin a howler........no probs landing, taxi off to shut down area.

Blades won't self wind down, you concerned bowt letin go stick to get up there to help stop em.......geez wat'll I do now............hell it's startin to gust even harder now.......shyte they is spinnin more

should I................hold stick full forward

part way

wait it out

back into wind

sideways into wind

[robP]

Any SMALL amount of forward stick done SLOWLY will not unload the rotors. If you are flying at say 60kn and you suddenly push the stick forward about 3", I would say you would run very close to unloading the rotors. You would go weightless in the seat, airflow would come over the top of the front section of the disk and its all over red rover. At 60kn if the engine quit, you would hold the stick steady until the machine stabilized as a sudden loss of power on some machines could slightly unsettle the pitch stability. You would probably be back to approx. 45kn at that stage. Then, very slowly, move the stick forward, probably an 1" or no more than 2". This will vary with each machine, depending on stick ratio and sensitivity. You need to get back between 45 and 55kn depending on weight of the aircraft, to be able to execute a successful landing. PIO or pilot induced ossilation has been the biggest culprit of unloading the rotors. It usually happens at higher speeds 50kn or above and it is caused by the pilot over correcting. All rotorcraft are sensitive in the pitch department and some control systems do not have enough forward movement back and forth. Stick should have a minimum of 12" for and aft. and preferably a bit more than that, for learning especially. Any forward movement of the stick that makes you feel lighter in the seat is to be avoided. So all movements are small and slow. That is basicly it but there more to the subject, regarding relative airflow at different speeds. This is a very important subject and one that needs to be thoroughly explained to the student, as it has unnecessarily ended a number of lives. Rob P

[bones]

Very good question Russ and one that i been meaning to ask myself, the way i had to stop them the other day yeah it was howlin, was to pull full back stick to get the gyro to back up behind the shed( i'm laxy i didnt want to start the motor agian) to get rotor(turbulence) from the shed to start putting wind throught the top of the rotors.
The old one wasnt a problem with the rotor brake, just engage it slightly and wait so them to slow...
But my first thought s for the original question would be to turn back into the wind with near full forward stick, just enough to see them slowing, but not all the way as if they went forward enough the wind could get under the back of them..
be gentle :pistoles:

[bones]

Nice to have you on board Rob, good advice... :wave:

[BeefBear]

Rob,

Thanks for your explanation. Most documentation talks about wind coming up through the rotors but in actual fact the relative wind acting on the rotors in normal flight is less than 45 degrees to the rotor would it not? What would be considered as a minimum safe angle for relative wind?

Ted

[Sonnyj]

Ted
It should be between 9 and 11 deg.
Rotor Thrust Vector – RTV:

The vector representation of Rotor Thrust usually depicted as an arrow with a specified magnitude and direction. In a gyroplane, the RTV is represented to be an upward and slightly aft pointing arrow approximately parallel and in-line with the spin axis of the rotor. The Rotor Thrust Vector is the vector sum of the Rotor Lift Vector and the Rotor Drag Vector. A common error in describing or attempting to understand the moments and forces acting on a gyro is to confuse or intermingle the use of both Rotor Drag and Rotor Thrust – one or the other convention must be utilized consistently throughout an analysis. For instance, if Rotor Thrust (combined lift and drag) is the representation of rotor forces used, then additionally describing the affect of a loss of Rotor Drag would be “double-dipping” the Rotor Drag component.
Sonny :beer:

[russ]

Rob.........firstly welcome on board, geez are we lucky here or what. :dance:

To the best of my knowledge this is the only forum "worldwide" that has an active blade manufacturer prepared to gives us all some factual feed back, rather than the second hand information we tend to get.

Your gained knowledge over these years is priceless, your preparedness to look outside "The window" and experiment with blades is applauded.

Looking forward to your teachings here :cheers:


post script...........another 2 credentialed guys are about to get onboard here also, mate are we lucky or what.... :dance: