Control conundrum

[Vance]

Thank you Doug, sorry it lost your long answer.

I was trying to use ground effect to calibrate my altitude, it seemed like the aircraft would go right through ground effect before I could respond unless I came in with a little power.

Dave wouldn’t let me land his Dominator, but he did five landings and I could always feel the ground effect. I believe that he was uncomfortable with my handicap. Could it be that the heavier machines take a different technique?

I will try landing with my eyes closed. That might be a good way for me to become more sensitive to the aircraft.

I have 319 landings in my logbook and it is still my week spot. I am beginning to feel dispirited. I haven’t bent anything yet, but my landings lack style and consistency.

Thank you, Vance

 

[Doug Riley]

Vance, I have no experience with the really big iron. My Dominator grosses around 900 and has a 28-foot rotor. I'd suspect that even the lead sleds have a detectable ground cushion if you get low enough and are travelling at the right airspeed.

 

[Vance]

Thank you Doug,

I have good control of my approach speed, the flare is the challenge.

I am going to work on being more sensitive to what the aircraft is telling me.

I am looking forward to trying the eyes closed landing.

Thank you, Vance

 

[Doug Riley]

Vance, some of the input is in the form of stick pressure. So some of the "feel" is in your hand, as well as in your posterior. The pressure is light; I'll try to get conscious of it next time I fly, but I believe it's a slight forward pull. If the instructor is also holding the stick, the input may not come through to you.

One thing you DON'T need once you "get" the process is the ASI!

 

[Ralph]

Vance,

Early on, the terminal portion of the landing, leading to touch-down, seems to run at warp speed. There doesn't seem to be time to do anything sophisticated and one tends to think of the "flare" as one thing which you are challenged to do at exactly the right time.

With time and practice, that terminal phase begins to run in slow-motion, stretching out for what appears to be a long time. You simultaneously perceive nuances you never had the time to notice previously and the whole thing stretches to provide lots of time to respond. Now the "flare" ceases to be an event and becomes a feedback-moderated sequence. Once you get to that point, you will wonder why you started by viewing the whole landing sequence as a rushed series of pre-programed responses.

Ralph

 

[Vance]

Thank you Doug,

You pined down another challenge I have. I have trouble equating the angle of the cabin with airspeed. I am inside too much. That is what I particularly liked about the Dominator, I could feel the wind and I found it cathartic.

Thank you, Vance

 

[Vance]

Thank you Ralph, I have found that with many things.

An unintended dismount from a motorcycle at speed seems interminable.

I will look forward to a slower and more relaxed experience.

Thank you, Vance

 

[Ga6riel]

Gabriel: Low speed bunt? What moment creates the bunting action? I trust you haven't fallen victim to the "gyroplanes inherently try to bunt over" fallacy. That is nonsense, but it's nonsense that has been promoted (in my opinion) by the ill-advised use of the vague term "bunt." We'd be better off sticking to "power pushover" and "drag-over."

Some gyros will nose over in low G because their designers made a mistake and deployed the moments and forces improperly. These "flips" are not an inherent or normal characteristic of gyroplanes. They ARE an inherent or normal characteristic of tailless aircraft with high thrustlines and/or moment-generating bits stuck out in the airstream. Flying wings and trikes are just as bunt-ish as gyros if they have unbalanced pitching moments. For that matter, if the H-stab falls off a Cessna, watch IT tumble, too.

A sharp gust from above-and-behind, in a CLT machine, is just as likely to generate a violent nose-UP moment. If actual tail-first airspeed were achieved, there'd probably be movement toward a violent yaw pirouette, as the tail feathers got back-winded. It would not be pretty. As Udi advises, stay out of mountain rotors; they're simply an unsafe place to be in a flying machine.

Something like this MAY have caused Ken Rehler's accident last December, although honestly it seems a bit far-fetched at 20 feet over a flat runway.

Vance, you're right about the potential for a torque rollover in low G, if the gyro uses rotor thrust as compensation for engine torque. Either a tall tail or differential incidence on the two sides of an immersed HS are better for this purpose, however, since they aren't G-dependent. At cruise power or more, the prop blast is much faster than the gyro's airspeed, so our hypothetical gust-from-behind isn't as likely to reduce the immersed tail feathers' airspeed to zero.

thanks Doug
my concerns centre around an issue that I failed to describe, that even where there is a stab airspeed can be so slight as to make the stab ineffective, ie the surface provides insufficient balance control.

Ive no idea where, but I thought I saw a description of such a condition that resulted in a bunt. It seemed feasable to me that low speed / nose down hence flatter rotor disc pitch to relative air and slowing rotor would present a dangerous condition

 

[Doug Riley]

"Slowing rotor" is indeed dangerous if it progresses to the point of a full blade stall in some sector of the disk. This is true of helicopters as well. We expect the gyro to "catch up" with any wind shears quickly enough to avoid catastrophic RRPM loss. In theory, a violent enough wind shear (or series of them) could put the rotor into non-recoverable, low RPM flap. This is an area where I'd like to see some numerical research... but we're talking about violent turbulence, enough to put any small aircraft in peril.

Low/zero G does not automatically induce "bunting" (hate that expression; it creates a mystery where none need be). Pitchover does not involve the rotor at all; it's caused by engine thrust or torque, or by the aerodynamics of the fuselage at higher airspeeds.

Obviously, the latter cause isn't a problem at zero airspeed. The HS and the draggy windshield, wheels or whatever both lose their force at the same rate as you slow down.

In contrast, the engine doesn't lose thrust or torque as you slow down. However, if the craft is CLT, then there's no engine-derived pitching moment to worry about at any airspeed. If the craft is HTL, then there IS a nose-down moment at zero airspeed. The logical way to counter this moment is with an immersed HS. If the HS receives slipstream air from the prop, then the HS's airspeed ISN'T zero, even if the gyro is standing still. The HS therefore continues to do its work at low airspeed, preventing pitchover.

Ditto in the roll axis. An immersed HS and/or an immersed tall tail can provide the moment needed to counter engine torque. These items will work even at zero aircraft airspeed, thanks to the prop blast.

Buntover is not a necessary concomitant of low/zero G. Low/zero G simply allows a design flaw (one that's always there, but normally masked by the rotor) to reveal itself. Fix the flaw, and pitchover is no longer an issue. RRPM is still an issue in strong turbulence.

 

[Brad_King]

Unnerving

Unnerving

Just yesterday, i found myself in an unnerving situation.[ well, it was unnerving 4 hours later when i was thinkn bout it.]
When i was turning tight in me 'new' ferel, i noticed the rotorhead was obsquering my vision of wot i was lookn at on the ground. This is nuthn new, but my headset/helmet is, and coz im ruged up like an eskymo and its a full face helmet, my neck movement is restricted and i have to 'lean out' of the seat in order to keep an eye on the critter. IOW, when the machine exceeds a 90* bank, i have to lean up[ like ona bike] in order to see the target.
As i sad, its nuthn new, but this occasion i happened to fly into a strong sink, and nearly fell out. But it was coz of the pitch control i still had in the 0g situation[ and full 912s power] i didn't loose control.

Man,what an interesting life the SCG has. Birdy you probably see more "unnerving" situations in a week than most pilots will see in a lifetime.

My hat's off to you sir.

Brad King
N6372K
Mad Max II LTC

 

[Aussie_Paul]

Thank you Paul, My wife is diabetic and she uses a needle, but what is the refrence to lumber? Is HTLMs a different kind of disease? What is cheek?

Thank you, Vance

Brian fly’s a High Thrust Line Machine (HTLM). The 4 X 2 lumber is to bash me around the ears for my stance on stable machines. He reckons maybe I have something else in the syringe!!!

Any time I make reference to stable machines like I did in post #13 they give me cheek as in a cheeky, disrespectfull kid!!!

There are quite a few Aussies who still think the pilot is the main stability provider in a gyro. They have not flown or flown in a truly a stable gyroplane yet.

I hope that I got around all of that for you Vance.

Vance, I have been an Insulin dependant Diabetic for over 36 years and my endocrinologist, whom I see 4 times a year to keep me flying, says I am in the best shape he has ever seen for Diabetic on Insulin for that many years. This I guess is due to my commitment to control and also some luck. The same commitment I have to safer gyroplanes and good training!!!!

Aussie Paul.

 

[Vance]

Thank you Paul and congratulations on controling you Diabeties.

Thank you, Vance

 

[Udi]

...2000fpm down [ or up] drafts are not theoretical, wether its caused by thermal activity or mechanical disturbance...

I never said they are theoretical Birdy, I said they are rare. Many people have flown thru them. However - 2000 fpm up or down drafts will get your attention reall quick - even if you are Birdy And they may be the door to the next world if you are flying an unstable machine and lack the experience to handle it.

Udi

 

[birdy]

Just a tip Vance;
I'v found with all side by side machines that if you flare to 0 or near 0 AS at touchdown the machine will all ways yaw to the side of the lightest person. The extra weight on one side of center, when the rotors are your breaks, will make it yaw if you have it at idle.
I saw a bloke landing his SH[ the only one i'v seen] and tho his touches were very neat and gentle, he'd always roll for bout 20', with the nose wheel in the air and rudder on full lock trying to stop the yaw caused by his weight being off center of the machine. If, for wot ever reason, [ like a lull in the head wind] that nose wheel touched the ground when it was pointing one way, and traveling another, it woulda been messy.
The symple solution is to keep a little power on for rudder authority, till you get a no roll landing sorted.
[ I didn't want to see the SH fall over, so i suggested to him to keep the rpm above bout 1500 for the rudder. to my supprise he listened to this SCG and i could watch him fly again without holding me breath.]
And i think he was just as supprised I gave a sh!t.

We expect the gyro to "catch up" with any wind shears quickly enough to avoid catastrophic RRPM loss. In theory, a violent enough wind shear (or series of them) could put the rotor into non-recoverable, low RPM flap.

I probably shouldn't post this but I'd like your thoughts on this Doug.
Whenever i fly into a sustained and streghtening down draft, that'd have the rotors looseing too much RPM, I hit full power[ if i'm not already on it] and start a hard bank to feed sum Gs in to the system.
In my small mind, this dose 2 things ,it Keeps the RRPM up and seems to lessen the 'jolt' when you exit the downer, probably coz the disc isn't being hit with such a high AOA when the airflow civilises.
This is a little unnerving at the first time, but i think its saved me ass a few times.

 

[Vance]

Thank you for the tip David. I am a zero roll landing enthusiast myself.

I have never had to use full rudder on a landing, but I always had somebody in the right seat. I suspect that Terry is 100 pounds lighter than I am, but the rudder was only to correct for cross winds unless I flared too high and gave it throttle. Then it would pitch up and turn right.

Thank you, Vance

 

[Chopper Reid]

Brian fly’s a High Thrust Line Machine (HTLM). The 4 X 2 lumber is to bash me around the ears for my stance on stable machines. He reckons maybe I have something else in the syringe!!!

Any time I make reference to stable machines like I did in post #13 they give me cheek as in a cheeky, disrespectfull kid!!!

There are quite a few Aussies who still think the pilot is the main stability provider in a gyro. They have not flown or flown in a truly a stable gyroplane yet.

I hope that I got around all of that for you Vance.

Vance, I have been an Insulin dependant Diabetic for over 36 years and my endocrinologist, whom I see 4 times a year to keep me flying, says I am in the best shape he has ever seen for Diabetic on Insulin for that many years. This I guess is due to my commitment to control and also some luck. The same commitment I have to safer gyroplanes and good training!!!!

Aussie Paul.

Thanks for giving the explanation although I wasnt refering to you being a diabetic, rather that your reply on stable gyros is the same every time !

Paul, I agree, a stable gyro is a good thing, particularly for those who have trouble flying ,doing only a few hours a year etc, I'm fortunate enough to feel very much at home and extremely safe in my gyro. I have had most stuff that weather can throw at anyone and never felt like the gyro was out of controll or that I wasnt in controll.

 

[Vance]

Thank you Brian,

That is why I asked. As colorful as colloquial speech is, it doesn’t work if everyone isn’t on the same page. Clearly Paul wasn’t on the same page and I don’t even have the book. Oops, that reference to a book is a colloquialism, it is speaking of a rulebook. Thank you for explaining your reference.

I find great value in accurate communication. It is exciting that we have people of so many backgrounds here, but sometimes it makes it a little harder to understand each other because we lack a common frame of reference.

To be sure I have it right, you’re saying that Paul should be hit with a large stick because he is like a scratched phonograph record that makes the needle skip and play the same part over and over.

In my experience that only exacerbates the challenge.

Thank you, Vance

 

[Aussie_Paul]

Thanks for giving the explanation although I wasnt refering to you being a diabetic, rather that your reply on stable gyros is the same every time !

Paul, I agree, a stable gyro is a good thing, particularly for those who have trouble flying ,doing only a few hours a year etc, I'm fortunate enough to feel very much at home and extremely safe in my gyro. I have had most stuff that weather can throw at anyone and never felt like the gyro was out of controll or that I wasnt in controll.

"Any time I make reference to stable machines like I did in post #13 they give me cheek as in a cheeky, disrespectfull kid!!!"

Brian, I rest my case!!

Ah ha, the stuck grammaphone needle repeating the same words. We have mp3 players now!!!!

Brian, I take that as a compliment, because it is working. Just look at how the gyro pics in the magazines, forums etc. have been changing over the last few years to stable designs. Thanks. Much appreciated.

Aussie Paul.

 

[Doug Riley]

Birdy, I asked the first gyro guy I ever met about this "zero G" stuff. He said he'd roll into a bank in response to it. If you're talking about a simple downdraft that creates a one-time change in AOA, the event is over before you can react to it. No need to bank and no time to, either.

But I think I know what you mean --a downer in which, as you punch deeper into it, the down-airspeed increases. This is NOT a single event, it's a gradient. In effect, it forces the gyro to do through a series of tiny down-accelerations.

Like the perfect storm, a certain combination of gradient and gyro airspeed will keep the gyro in low G longer than a simple downdraft. The gyro is trying to keep up with the down air, but the down air keeps speeding up and running away from the gyro. This leads to sustained low or zero AOA, which costs you rotor RRPM.

In true zero G with a teeter hinge, you can't bank because you have no rotor thrust left to create the bank. Conversely, if you CAN bank, you're not in zero G. I agree that you ought to bank while you still can. A downer that approaches a banked rotor is attacking it slantwise rather than squarely on top. This means that it will affect rotor AOA less.

My own tactic for dealing with rough stuff (I'm sure I haven't been in 2000 fpm vertical turbulence) in my old HTL unstable rig was to slow down to, at most, the airspeed that required the least engine RPM. Often I'd go even slower than that (e.g. 30 mph) and tolerate a gentle mush. The thinking was that (a) a low airspeed means the gyro passes through any gradients at a slower pace, allowing more time for RRPM to adjust and b) a lower power setting leaves less prop thrust to power a PPO.

Now, in the Dominator, I hold the stick firmly and don't power down. I do slow down to economy cruise, though.

I'm only joyriding, not working moo-cows. Your needs may differ!

 

[Ralph]

With respect to "sustained" events, once the aircraft has stabilized in the moving air mass, there are no further issues until it transiitions into still another air mass with different properties. Once "inside" a moving mass of air, the machine operates normally, whether the air is rising, falling, or moving laterally at any velocity, and that includes the ability to maneuver and maintain autorotation.

It is the transitions into or out of air masses with very different properties that pose a hazard, not "sustained" conditions. Of course relativity only goes so far. If you are flying in a mass of air headed for terra firma at -2000 fpm, you had better hope that you started high and that it won't take long to fly out of the cell! :=)

Ralph