Dynamic Rollover

[BOP Flyer]

HI everyone,

Can anyone tell me if gyro's suffer from dynamic rollover effect the same as a two blade helicopter such as the Bell Jet ranger ?

Cheers Barry

 

[GyroChuck]

Reynamic Rollover

Dynamic rollover in a helicopter is a result of the rotor thrust pulling the copter over and not having enough cyclic to correct for the tip over motion. Once the critical roll over angle is reached recovery is impossible. The corrective action is to drop the collective and get both skids back on the ground. Dynamic rollover in a helicopter mostly happens when lifting off from a surface and one of the skids gets stuck.

In a gyro a rollover usually occurs when landing with a crosswind and enough corrective action is not taken to account for the crosswind. Then what happens is the wind from the side will get under your rotor, causing more lift on the one side. Thus picking up the gyro on the one side and tipping it over. Again once the critical angle is reached there is no point of return. Corrective action would be to keep the stick into the wind and once the gyro is stopped get the stick forward. Once the stick is forward the rotors will not produce enough lift to tip you over.

So I would say Dynamic rollover occurs in both but the cause is for 2 different reasons.

 

[BOP Flyer]

Reynamic Rollover

Hi Chuck, Thanks for the reply. I now understand how it happens and it is good to know how to prevent it. Again shows the importance of good training, and practice!

It is really great how everyone on here will help out everyone else. This is a wonderful resource for both the experienced and the new pilot.

Thanks Barry

 

[gyropilot]

Reynamic Rollover

GyroChuck said:

"In a gyro a rollover usually occurs when landing with a crosswind and enough corrective action is not taken to account for the crosswind. Then what happens is the wind from the side will get under your rotor, causing more lift on the one side. Thus picking up the gyro on the one side and tipping it over."

Chuck,

Rather than saying the rotor disk creates more lift on one side than the other (the upwind side), wouldn't it be more accurate to say:

When landing in a crosswind with sideways movement (in relation to the ground), the downwind main landing gear tire can become a pivot point, by which the rotor can lift the gyro over onto it's side.

Similar to a dynamic rollover in a helicopter, the gyroplane's roll rate can quickly build whereby a critical roll angle is exceeded making roll recovery impossible, even with full opposite lateral cyclic input.

Then again I could be wrong!

John Landry

 

[Gary_in_Orygun]

Reynamic Rollover

John, we know you are never wrong. ;D

 

[GyroChuck]

Reynamic Rollover

John, I would say you are correct with your statement. If landing with a sideward movement it's the same as a dynamic rollover.

With most of the people I have taught, they have gotten into trouble after touching down in a straight line. Then on rollout and almost stopped and both wheels on the ground. They get lax and stop correcting for the cross wind. Before they know it one wheel gets picked up and the gyro starts getting tipped over. They usally get supprised so I correct with stick all the way into the wind and forward.

I guess you could get into this same situation on takeoff also. The upwind wheel wheel comes off the ground. But the gyro gets airborn so quickly the dynamic rollover doesn't have enough time to fully develop. The gyro just gets blown sideways off the runway after airborn. Till the pilot realizes he needs a little more correction.

So in both these situations a pivot point is needed.

I could have added more to my first post, but I'm a lazy writer and I don't like writing. Thats why I try to leave the answers to people who seem to have a flair for writing and explaing things simply.

 

[gyropilot]

Reynamic Rollover

Hi Chuck,

I understand what you mean about putting complicated thoughts in writing... it's sometimes difficult and takes practice. I'm not very good at it myself... you ought to see how many time I have to revise something on my end prior to making a post before I feel it conveys a point clearly enough to share with the public.

Anyway... one of the main things I wanted to point out in this discussion was that technically speaking, unlike the wing of a fixed wing aircraft, a gyro rotor disk isn't lifted more on "one side" or the other. If I'm not mistaken, in a teetering rotor system the lift created by the rotor disk always acts through the teeter bolt (unless of course the hub bar is hitting the teetering stops... but that's not normal and not what I'm taking about). The teetering action of the rotor assures lift is equalized and passed through the teeter bolt.

Now of course this lift is vectored in some direction, and *that* is what causes the gyro to roll up and possibly over if the conditions are right (such as having a pivot point and insufficient lift to get airborne).

All that being said, obviously the most important thing is what you are already teaching your students... land without a crab (or shrimp, steak, or baked potato for that matter) and then upon landing get that rotor disk tilted into the wind! But I still feel it's important for students to correctly understand how the teetering rotor system works and why things happen the way they do. Ignorance and / or misconceptions can lead to a tragic result (like a PPO death caused by a high thrust line).

Best regards,

John L.

 

[Chuck Irby]

Reynamic Rollover

Chuck and John,

We newer pilots can learn a lot from you more experienced pilots. Thank you both for your input on this topic. I, for one (and I am quite sure there are many others), would really like to hear more from you guys on anything you feel might make us newbies better and safer pilots.

Thanks again,

 

[gyropilot]

Reynamic Rollover

Chuck Irby said:

"We newer pilots can learn a lot from you more experienced pilots. Thank you both for your input on this topic. I, for one (and I am quite sure there are many others), would really like to hear more from you guys on anything you feel might make us newbies better and safer pilots."

Thanks Chuck, but I don't consider myself very experienced... just a student who's always learning something new.

Here are some flying suggestions I try to live by...

• Never fly over something you can't successfully land on... or at least live to tell about it. While flying, frequently ask yourself what would you do right *now* if the engine were to quit. Evaluate and critique your options at that moment and be honest about it. Change your flight path if needed.
  
• Practice engine-idle landings frequently to simulate real engine-out landings. (Some pilots practice real engine-off landings, which is even better). Once you initiate the maneuver, don't use the throttle unless absolutely necessary to prevent an accident. In a real engine failure, the throttle won't work.
  
• Don't getting complacent. Fly like everyone and everything is trying to kill you... that includes your own gyro! Assume no one can see you or hear you... because usually they can't.
  
• Never overestimate your's, or the aircraft's, limitations. Proceed slowly and always be ready to back off. Don't feel pressured into doing things you don't feel ready for. When you're still alive, there's always tomorrow to go fly. If you're dead...
  
• Forgetting something important can kill you! Check everything twice and never assume "it'll be all right." When in doubt, land and check it out!
  
• Stay legal and act professional at all times. Gyroplanes are rare out there, and like it or not, each one of us is a representative for the entire gyroplane community. There's a lot of well-deserved prejudice against gyroplanes and gyro pilots out there which we're slowly overcoming.
  
• Stay well clear of Gary Kaminsky's gyro when he's landing in a crosswind.

Best regards,

John L.

 

[Chuck Irby]

Reynamic Rollover

Thanx John, I'll take it all to heart, especially the last line.

 

[mceagle]

Reynamic Rollover

A dynamic roll over in a gyro is not normally something that can happen out of the blue, it is normally pilot induced. The exception is when a pilot is compelled to land sideways on a slope of 9 degrees or more.
When doing a normal landing, The gyro is "flared" 6" to 12" above the ground and held off until it sinks on with full back stick. The sinking on indicates that the rotor speed has started to decay and the rotors are no longer able to support (or lift)the aircraft.
Landing into a strong wind is a different matter. The gyro cannot be fully "flared" or it will touch down going backwards. Consequently it must be flown on with a bit of power, and even though you may have no forward speed as far as the ground is concerned, the rotor is still flying and supporting the aircraft. As the gyro comes to a standstill, the stick is gently moved to the centre full forward position and the power is bled off just the right amount to stop the Gyro rolling backwards. With the stick full forward, the rotors loose speed very quickly and the gyro is safe to taxi in any direction within a few seconds. If any side stick is used in a strong cross wind, it should only be a small amount into wind and even then only after a few seconds have elapsed to kill the lift in the blades.
The other time that a dynamic roll over can ocurr is with a crabbing take off or landing. This is piolot error and is usually seen with beginners doing their first hops.