Research report on slips in a gyro

SGK

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I am sorry I don't know more than I wrote in the thread. But I am also eager to learn and will not hold back any information when I get the full written report.

Thank you Chris.
I hoped that someone else would jump in and try to answer my question before results of your analysis come to daylight. I've got information that German training material, at least a few years ago, advocated side slips to the side of the forward moving rotor blade. Our training material has been made by that time by good people with good intentions but with limited experience. The German routines, as most developed by that time, have been implemented into our training material and practiced by our instructors.
There are apparently many pilots around that use this method routinely after being taught during elementary training.

No one else in my neighborhood has ever questioned this method, often used for height reduction on approach.
I feel that there is no need for this manoeuvre and use to tell my students to forget this part of the book, especially the detail that advocates side slipping towards forward moving rotor blade.

Help needed to understand.

Roman
www.gyroflyg.se
 
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birdy

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My question, is what makes this a dangerous maneuver???
Rong combination of pilot and machine.
Sum machines will be more prone to rolln over than others due to different levels of side drag, and different power to weight ratios**.
The pilots awareness of the hazards will determin how hard he pushs it.
Been do'n um for years, in all sorts of air, generaly onder 100', horisontaly, decending or climbing, and only once have i felt the onset of torque roll, and yes, it grabs your attention like a shot in the ass, if your awake.

**High power to weight machines can, at low ASs, transfer a considerable portion of the machines weight to the prop, slown the rotor while addn alot of torque moment to the frame. If this machine has the rong pilot init, the limit can be reached without the pilot regestern the fact that he's about to go over. By the time he dose, its too late.
A low powered machine will sink long before the roll limit is reached.
 

SandL

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Slip Vs VD

Slip Vs VD

I generally use neither slip nor vertical descent (VD), shouldn't need to if you circuit is right your approach will be right etc.
But I have noticed whilst messing around in the upper air that the recovery height from a VD to approach speed is considerably more than recovery from a slip to normal approach speed , maybe this is the reason that people use slip as oppose to VD to get rid of unwanted height.
Personally, if for some reason I screw up my circuit on an engine out I would feel ok entering a slip of (varying degrees deppending on height) with airspeed at say 500 ft knowing I can kick it off at say 2-300 ft and still land softly. With my low experience, I would not consider entering a VD under 500 ft. I would rather S turn on base leg or if impossible then slip would be my only option .
Thanks to this thread I will always lead with left rudder (but not necessary with an engine out I guess !)
Great thread thanks so much
Peter
 

WaspAir

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Hi, Vance -
just catching up on this thread and I noticed this:

I had to fly both down wind and final so the slips were both to the left and right.

which confused me a bit.

Why would you ever need uncoordinated flight on downwind, when only ground track matters?
 

Vance

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Not a commanded slip.

Not a commanded slip.

Hi, Vance -
just catching up on this thread and I noticed this:



which confused me a bit.

Why would you ever need uncoordinated flight on downwind, when only ground track matters?

The gusts were out of line with the main wind so when I would hit a gust we would spend some time in a slip until she realigned herself and again when the gust stopped.

The response to the gusts reversed as I flew downwind and then final.

Thank you, Vance
 

ckurz7000

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Chris nice report.
some comments are... slip study is for the specific gyroplane (MTO / ELA etc) as they posses almost the same aerodynamics, and it is not the same to other gyroplanes.. ( we do not have any effect from slipping our gyroplanes either way).

Of course there will be differences between different models of gyros on how they behave in a slip. Nonetheless, the factors mentioned will be the same in principle. Their magnitude of influence may change but not the physics causing them.

also the effect of the downwash on the fuselage is true on helicopters.... but how much downwash is there on a Gyroplane????

There's enough of it so that it is partially responsible to cause a noticable ground effect. The interpretation that air flows upwards though the rotor and hence nothing below the rotor can possible have an effect doesn't hold true.

Other factors that effect the side slipping on those gyroplanes are the winglets on the HS masking the ruder and the frame reaction of the engine torque/ helical prop wash in conjunction with having the frame hanging from one side and not the center.

Yes, I agree with this.

-- Chris.
 

JAL

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I generally use neither slip nor vertical descent (VD), shouldn't need to if you circuit is right your approach will be right etc.
But I have noticed whilst messing around in the upper air that the recovery height from a VD to approach speed is considerably more than recovery from a slip to normal approach speed , maybe this is the reason that people use slip as oppose to VD to get rid of unwanted height.
Personally, if for some reason I screw up my circuit on an engine out I would feel ok entering a slip of (varying degrees deppending on height) with airspeed at say 500 ft knowing I can kick it off at say 2-300 ft and still land softly. With my low experience, I would not consider entering a VD under 500 ft. I would rather S turn on base leg or if impossible then slip would be my only option .
Thanks to this thread I will always lead with left rudder (but not necessary with an engine out I guess !)
Great thread thanks so much
Peter

The point of the slip is you should be able maintain the steeper approach all the way to the ground and then kick the gyro straight on the round out. A properly executed slip should not result in a change of airspeed, it should only result in a steeper than normal approach at the same airspeed (I am referring to using sideslip to steepen descent in the case of emergency, the actual opposite happens when using side slip to land crosswind, that is you crab down final (into wind) and enter the sideslip to align with the centreline when approaching the the ground.)

From what I am gathering from this thread is that most experienced gyro pilots don't use them as they achieve the same result with a VD even though you recover from the VD several hundred feet altitude.

Also I think the irony of this thread is that those gyros that benefit from slipping (ie those with a lot of side surface area to produce enough drag to make a difference) are the ones at most risk of drag over.

Open style gyros probably get little benefit from sideslip but are probably quite safe to do them in compared to the semi-enclosed gyros.
 
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ckurz7000

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Hi Vance, thanks for your questions and remarks which seem to come right out of your flying experience.

Vance said:
The gusts were out of line with the main wind so when I would hit a gust we would spend some time in a slip until she realigned herself and again when the gust stopped.

The conditions of your, more or less, inadvertant slips caused by wind gusts is quite different from an intentional slip. You didn't enter the slip in a defined way but -- at last that's how I understand it -- suddenly found yourself flying sideways through the air. Under these circumstances the "safe slip" procedure I posted can't be followed point by point, of course. You already should be flying at the reduced Vra (rough air speed). This would also not be conditions in which I would use intentional slips over and above those to which wind gusts subject me anyway.

In addition, different models of gyros will behave differently in slips. Whatever I say and write is meant to apply in principle but at varying degrees to different gyros. That's why stability in slips is part of the mandatory flight test program according to BCAR Section T.

The points I raise are meant to outline the existence of a stability margin and motivate the reasons behind it. The "safe slip" procedure I mention is, in my opinion and those of others, the safest way to ensure that you will never experience irrecoverable attitudes during slips. Of course you can enter slips at faster speeds, change throttle while slipping, lead with the stick on entering and all that. Will you tumble out of the sky because of this? Probably not, but your stability margin will be a bit less. If you had enough of it to begin with you wouldn't even notice it.

Greetings, -- Chris.
 
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ckurz7000

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The German routines, as most developed by that time, have been implemented into our training material and practiced by our instructors.
There are apparently many pilots around that use this method routinely after being taught during elementary training.

No one else in my neighborhood has ever questioned this method, often used for height reduction on approach.

Hi Roman, in my experience there are big differences among different countries regarding the collective knowledge about gyro flying in that country. Some countries have a longstanding tradition, such as France, Spain, Italy or the US. Other countries, among which I also count Germany, are relative newcomers to this sport.

It would have been great if the experience of people with a lot of gyro experience that have been flying and training students for decades, had been drawn on when writing a training syllabus. For example, the German syllabus initially taught students to taxi after landing with the stick back and the rotor spinning. The rationale was that a spinning rotor was less likely to encounter blad flapping. This is, of course, totally bogus und has since been removed.

The point is, if people instrumental in writing the German training syllabus had first talked to other CFIs abroad, who had much more experience, some mistakes would not have been made.

I feel that there is no need for this manoeuvre and use to tell my students to forget this part of the book, especially the detail that advocates side slipping towards forward moving rotor blade.

A larger reprtoir of maneuvers you can perform safely and with confidence makes you a better pilot. Having more tools available to you will also make you a safer pilot. Therefore I always try to enlarge my toolset and am proud of any new addition.

-- Chris.
 

SGK

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Hi Roman, in my experience there are big differences among different countries regarding the collective knowledge about gyro flying in that country. Some countries have a longstanding tradition, such as France, Spain, Italy or the US. Other countries, among which I also count Germany, are relative newcomers to this sport.

It would have been great if the experience of people with a lot of gyro experience that have been flying and training students for decades, had been drawn on when writing a training syllabus. For example, the German syllabus initially taught students to taxi after landing with the stick back and the rotor spinning. The rationale was that a spinning rotor was less likely to encounter blad flapping. This is, of course, totally bogus und has since been removed.

The point is, if people instrumental in writing the German training syllabus had first talked to other CFIs abroad, who had much more experience, some mistakes would not have been made.



A larger reprtoir of maneuvers you can perform safely and with confidence makes you a better pilot. Having more tools available to you will also make you a safer pilot. Therefore I always try to enlarge my toolset and am proud of any new addition.

-- Chris.

Well said, totally aggree. Unfortunatelly, lack of information, foreign language and cultural differences, milage and tradition as well as personal ego in some cases were obstacles to dig deeper into it than to cut 'n paste from, by that time, realatively well done and modern German syllabus.
Anyway, I'm still struggling to understand some details. Besides, as I can see, there are others here that need to reconsider their way of thinking.
I admire your attitude radiating from your last sentence. I would like to see more instructors with this kind of view.
Still, I use this particular case with mysterious side slips as a way of pointing to the students that in the whole toolbox available for angle of aproach adjustments, this one is both less effective and gives less safety margins than any other performed correctly. That definitely doesn't mean that we don't train it (in accordance with your ideas) but once more, not as a part of height reduction on approach.
 
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SandL

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Left slip

Left slip

Hi Peter,
Please explain. I can't see what you see in this thread.
Roman

It appears that a slip to the left is different to a slip to the right, a left rudder slip in a gyro with an anti-clockwise prop (viewed from the rear) appears less suseptable to torque and drag over... did I get it right ?, but I am in a low powered gyro right now, so not a big issue but worth while taking notice of
 

ferranrosello

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Gents, be aware that we are talking about what reduces to a minimum the stability margins in a side slip. Nobody is saying, by now, that our gyros become unstable in a side slip...

The only things we know, thanks to Chris first post, are:

.-the most aggressive the side slip, the smaller the stability margin.
.- If you are side slipping to the same direction that the rotor turns, the stability margin is reduced.
.- If you are slipping to the opposite side to which the propeller is rotating, the stability margin is reduced.

All these are wise considerations if you are going to perform side slips. But we don't know where is it the real limit. We know that some accidents have happened when doing extremely aggressive side slips. So we could infer that maybe that there is a limit. And the best advice is not conduct very aggressive sideslips.

That's to say fly properly. I understand why Chris states leading the side slip with rudder. But I'm entering a side slip using the stick and immediately using the proper pedal to avoid any heading change. This must be done coordinately. To end the side slip is the same, first less lateral stick, and with the rudder, just keep your heading. No more secrets... But the requested coordination requires practice and not rapid side slip maneuvers until you are skilful enough.

Doing the side slips in the proper way, imply no problems. The problems arise when overconfident pilots push the limits... Then they are not flying perfectly controlled side slips, but mechanically kicking the pedals and abruptly moving the stick in a totally uncoordinated maneuver.

I can summarize this question to only one: fly your rotor smoothly. A rotor cannot be mistreated in flight.

Ferran
 

XXavier

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It looks like this is shared by more people here.
I would appreciate someone's explanation.

It might have to do with the lateral inclination of the disk due to coning. The following is quoted from 'Development of the Autogiro: A Technical Perspective', by J. Gordon Leishman

[...]In addition, the rotor disk also has a tendency to tilt laterally slightly to the right (for a rotor turning in a counterclockwise direction). This effect arises because of blade-flapping displacement (coning). For the coned rotor the blade angle of attack is decreased when the blade is at ψ = 0 deg and increased when ψ = 180 deg. Again, another source of periodic forcing is produced, but now this is phased 90 deg out of phase compared to the effect discussed before. Because of the 90-deg force/displacement lag of the blade-flapping response, this results in a lateral tilt of the rotor disk.[...]

As seen by the pilot, if the rotor turns counterclockwise, you should be careful with tilting the rotor to the right, since the disk is already slightly tilted to that side. And, if the rotor turns clockwise, the left side is the one to be careful with...
 

C. Beaty

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A coned rotor tilts sideways because the leading blade has a slightly higher angle of attack than the trailing blade.

With the usual direction of rotation, the rotor tilts slightly to the right while in forward flight, requiring a bit of left stick to keep going straight and level.

That, combined with uncompensated propeller torque makes a slip to the right the coffin corner (CCW propeller rotation viewed from the rear).
 

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