Research report on slips in a gyro

All_In

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Most excellent thread and information, and it makes sense.

Thank you so much for sharing.
 

Doug Riley

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In fact, no more lift is made on the advancing side of the rotor disk than on the retreating side.

This WOULD be the case were it not for the flap or teeter hinge(s). These hinges cause an automatic cyclic-pitch change pattern at a 1/rev frequency for each blade. This cyclic pitch change happens to lead the dissymmetry of blade airspeed by 90 degrees. It eliminates the (potential) dissymmetry of lift caused by the dissymmetry of airspeed.

As a slip develops, the rotor's "blowback" effect should kick in. The rotor disk should begin to tip away from the direction the slip. The gyro therefore should begin the slow its travel in the slipping direction, unless more side-stick is added.

No doubt a large source of drag located below the gyro's CG can easily overwhelm this weak dihedral effect and produce a tendency to capsize at high speeds and throttle settings.

I would REALLY be relieved to see the designers of the expensive Magni-class Euro-gyros move their body pods higher, so the slipping drag is not centered below the CG. That would make the cautions in the report less necessary IMHO.
 

Vance

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Dissymmetry of lift and the Teetering rotor.

Dissymmetry of lift and the Teetering rotor.

Thank you Doug.

That was my understanding also so I was surprised to find that it is obvious to Greg that more lift is created by the advancing blade than the retreating blade and this apparently couples with torque roll in gyroplane slips.

Greg seemed to have gained some understanding from the report that I had missed so I asked.

There is so much about how a gyroplane flies that eludes me.

I am not able to visualize what Greg describes.

Perhaps it is because I don’t understand his terminology.

Thank you, Vance
 
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EI-GYRO

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I would REALLY be relieved to see the designers of the expensive Magni-class Euro-gyros move their body pods higher, so the slipping drag is not centered below the CG. That would make the cautions in the report less necessary IMHO.

That would make them Predators, no ?
 

cburg

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Thanks Abid, I’m familiar with the gearbox. However, I’m building a twin engine coaxial shaft re-drive for two 582’s…a poor (or frugal) man’s 914.


I saw a pilot at the same airport that Chris flies at (near Austria) in his MTO that did a lot more than this gentleman. Probably some of the most aggressive gyroplane slips and turns I have seen including the guys in Florida. Obviously these can be done safely based on pilot technique.

An acquaintance of mine in Austria designed a trike with a Rotax 582 Blue Head with his own gearbox with counter-rotating propellers. Trikes don't have a tail so the torque problem is hard on them and the designers do some tricks to reduce the effects of torque. I am not sure what happened to his gearbox but he had quite a few hours on it and it seemed to be successful. I guess its more complex and expensive and that's why not very popular in aviation compared to dealing with torque effects in design and pilot technique.

Chuck: If you are interested in a counter-rotating gearbox. Here is the website of my acquaintance
http://www.sunflightcraft.com/en/coaxp.php

You can see the trikes it has been installed on already. He is a nice guy and a great trike enthusiast.
 

cburg

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The Law of the Pioneer…”if someone else did it and survived it must be safe enough.”

It’s a common and dangerous notion…but admittedly through incrementalization the envelope is pushed and things advance.

Bless the pioneers of this world…and hope for their continued survival. We enjoy the fruits of their risks, successes and failures every day.

Much of our technology and knowledge is written in blood…unfortunately.



If everything is the same, the outcome will be the same. Feeling has nothing to do with it.
The outcome is only different because something was not the same. The variable are weather and pilot technique if the machines are the same.
 

Vance

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I seem to be doing everything wrong!

I seem to be doing everything wrong!

Hello Chris,

I have hesitated to post this because I don’t want to muck up your useful thread.

Based on the summation I did a lot wrong today.

I had cruse power in at more than 80 kilometers per hour (43kts) and had enough power in to fly straight and level at 129 kilometers per hour (75kts).

The winds were 320 at 20 kts gusting to 350degrees at 28kts for landing on runway 30.

In other words there was not a way to avoid a transient 30 degree slip.

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

I did not lead with the rudder because I was responding to the gusts.

My ASI was showing gusts of about 10kts and the highest readings were typically at the maximum slip angle. My sense was that the ASI was reality based despite 30 plus degrees of slip.

In gusting conditions I like to have some power in to give The Predator more rudder authority so if a gust drops me down I am still lined up with the runway.

I typically manage a gusty landing at 60kts indicated air speed until my round out and descend at 500 feet per minute with 400 less rpm than cruise power.

My engine turns anticlockwise as viewed from the rear and the rotor turns anticlockwise as viewed from above.

I did not notice a difference between a left or right slip although I was at 75kts IAS on down wind and slowed to 60kts IAS on final so if there is a difference I might have missed it. In aggressive maneuvering one of us likes to turn left better than right.

The lateral cyclic and rudder never achieved neutral.

The landing was uneventful but as I understand the summery I did nearly everything wrong.

My current wind limit is 35kts with a ten kt gust spread so I have been in much more difficult conditions than today. I have had the gusts at well over forty degrees divergence from the wind direction.

Please understand I am not disagreeing with the summation.

I would like to understand how close to the edge I am.

I didn’t ever see more than around 15 degrees of bank and all of her responses seemed proportional to my cyclic and rudder input.

My descent rate was all over the place including a balloon near the ground with a very nice touch down.

None of my CFIs taught me how to fly in this sort of wind so I am just winging it.

Thank you, Vance
 
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feedpro

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I am really dumb about flying a gyro, but dumb old me would simply land into the wind at a taxi way, same as I did for years with my fixed wing when the wind was too strong, the hell with a slip.

Why is this wrong?
 

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I am really dumb about flying a gyro, but dumb old me would simply land into the wind at a taxi way, same as I did for years with my fixed wing when the wind was too strong, the hell with a slip.

Why is this wrong?
Hello Karl

That is the correct procedure = at any time the wind speed and/or angle is past your maximums, even for those who always use slips!
 
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Vance

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In a strong steady wind I land into the wind.

In a strong steady wind I land into the wind.

I am really dumb about flying a gyro, but dumb old me would simply land into the wind at a taxi way, same as I did for years with my fixed wing when the wind was too strong, the hell with a slip.

Why is this wrong?

I don't remember anyone posting that landing into the wind in a gyroplane is wrong Karl.

The report and my question is about slips.

I could land into the wind if the gusts were coming from the same direction as the main wind.

There was a thirty degree spread and the gyroplane could not keep up with the gusts so she was often flying in a slip.

I am trying to apply what Chris has summarized to the conditions I often fly in and the gyroplane I am flying.

I am not a slip enthusiast although I agree with Chris that it is easier to pull off a quick descent with a slip than a low speed or vertical descent.

My questions are not related to slips for descent either although The Predator descends more quickly when she is in a slip even when the indicated air speed increases.

If an incorrectly done slip can tip a gyroplane over and I am doing so much wrong I am wondering how to do it better.

Thank you, Vance
 

Doug Riley

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Fergus, regarding your #44: yes, the Predator, Hinchman H-1, Xenon and other designs have placed the pod up on a nose gear leg and so lessened the amount of proverse slip-roll coupling. It's not hard to test for this problem with a large mock-up of the pod and crew and a roll pivot located where the CM would be on the real craft. Mount the mockup assembly on the front or roof of a truck and drive. A spring scale can be used to gather numbers for the rolling moment created during skewed flight.

The effect of the wake of the fuselage on airflow into the rotor, as mentioned in the report, is harder to test for in a simple simulation.
 

feedpro

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Another dumb question.

My limited knowledge does not ever include slips as a necessary part of normal flight.

Cross winds can be handled safer by landing into the wind and that might be across a runway or at an angle. At home, I am like Birdy and land in front of my hanger. Power off, a gyro decends very steep. Compared to a fixed wing where a slip is sometimes necessary to get rid of altitude inorder to spot land in a tight spot.

I do not roll when I land even in calm wind. I will never land at a tower controlled airport in my gyro, but would suspect that they would be happy that I lit across the runway and was able to exit immediately.

So point me in the direction where a slip would be necessary for a safe flight.
 
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Vance

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I am not a slip enthusiast.

I am not a slip enthusiast.

Another dumb question.

My limited knowledge does not ever include slips as a necessary part of normal flight.

Cross winds can be handled safer by landing into the wind and that might be across a runway or at an angle. At home, I am like Birdy and land in front of my hanger. Power off, a gyro decends very steep. Compared to a fixed wing where a slip is sometimes necessary to get rid of altitude inorder to spot land in a tight spot.

I do not roll when I land even in calm wind. I will never land at a tower controlled airport in my gyro, but would suspect that they would be happy that I lit across the runway and was able to exit immediately.

So point me in the direction where a slip would be necessary for a safe flight.

Hello Karl,

I suspect I don’t understand your question Karl.

I feel there is value in defining terms so from Wikipedia we have:

A slip is an aerodynamic state where an aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow. In other words, for a conventional aircraft, the nose will not be pointing directly into the relative wind (in the side-to-side sense). A slip is also a piloting maneuver where the pilot deliberately puts the aircraft into a slip.

Chris has posted that it is an advanced maneuver.

In my experience an intentional slip is another way to get the gyroplane exactly where I want it.

Why wouldn’t I want to practice slips if it is an option?

In my opinion it is not necessary to do advanced maneuvers.

I find in turbulent air The Predator is often in a slip and generally she weathervanes into the relative wind quickly without much input from me.

The situation I describe in post forty seven is another situation where I end up flying in a slip.

I am trying to understand how to manage it better.

One of the things I love about flying gyroplanes is all the options I have.

I love to practice those options.

If you like always landing into the wind with no forward roll that is probably what you should do.

I cannot think of a compelling reason to intentionally slip a gyroplane.

Thank you, Vance
 

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Another dumb question.
...
So point me in the direction where a slip would be necessary for a safe flight.
Karl, I do not have the experience in a gyroplane to know, what would you do in an emergency landing when there is only a road surrounded by brush with a crosswind or a small beach with the ocean on one side and a cliff on the other, forcing you to land in a crosswind? (like in So. Ca.)

I would think that with our terrain it would be nice to be good at this maneuver in other instances too when the only place to land off airport is with a crosswind?

PS:
In a FW without a slip it would be impossible for me to land many places I can now, so it is hard to understand why I would not wish to learn how with my gyroplane as least for emergency landings. (Which means I need to be good at it)
 
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Aviomania

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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).

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

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what would you do in an emergency landing when there is only a road surrounded by brush with a crosswind or a small beach with the ocean on one side and a cliff on the other,
Same as normal.



but how much downwash is there on a Gyroplane????
Next to nuthn, definatly not enuf to have any advers effects.
[ cept of course, in an inertia hover. ;)]
 

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Hello,

I would doubt, that lifting the dragging body up, will remove ALL banking problems. Clearly it would improve the negative effect, but, as opposed to prop-torque and PPO effects, this time it is not about the torque around the CoG, but the torque about the rotor head.

The Rotor has a certain, not much changing air resistance, if you keep flying the same airspeed. Turning the fuselage sideways will suddenly increase the air resistance below the rotor, regardless of CoG position.
The higher the fuselage, the less it has effect, but still, there is an effect. I trust that a small sideways profile of a gyro will reduce the difference between straight and slip flight and therefore have no ill effect, but then again, also no intended brake effect. Why would you then slip, other than frighten onlookers?

Kai.
 

Gyro28866

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I am a little confused, with this discussion. I come from the Fixed wing world. I started in Gliders, transitioned into a J3 Cub. Then purchased a Cessna 150, then a 108-1 Stinson. Then I took a ride in a gyro.
For fun, this is the only way to fly!!!
In the gliders and the J3, slips and skids were part of normal flight, especially the landings. Loved the side slips, push it and see how close in alignment you could get the wing tip to the runway. Slips are used to reduce lift and increase drag in a controlled manner. Or in other words, Increase rate of decent and not increase airspeed!
This is a controlled Un-coordinated flight maneuver. There are specific/designs of fixed wing aircraft which place design limits on this maneuver. In a Forward slip on an approach to land you can run out of rudder authority to align the longitudinal axis to the runway in a strong crosswind; this is known as the aircraft's maximum crosswind component. I have found my rudder pedal at full deflection and still not able to align the aircraft, I just go around and try again in a few minutes.
So, I have tried to explain my perception of all this so I can ask some questions?

When we are doing a little showing off, and pass (in the demonstration "BOX" at Mentone) by some spectators and "fly sideways" we are executing a "Forward Slip and maintaining Altitude. To me, this is a ground reference maneuver. Depending on the crosswind component, a yaw (rudder input) to the left or to the right is basically the same, but you will run out of rudder authority on one side before the other. The control stick will be cross controlling the rotor (wing) just as in the fixed wing. If the crosswind is 45 degree to the flight path and if the rudder can provide 45 degree input; then the result is what appears to be a sideways flight to the spectators.
I have executed this maneuver in both my Bensen and in the Dominator with no noticeable bad flight handling characteristics demonstrated by either machine.
We have all seen this done at fly-ins.

My question, is what makes this a dangerous maneuver???
 

Gyro28866

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Sorry, left for a while to go to church.
In the fixed wing world; if we are in a slow flight configuration just slightly above the stall speed. Apply hard rudder to yaw the aircraft and also apply opposite aileron (cross control) and then pull back on the stick to apply a pitching moment up. The aircraft will stall one wing and roll on its longitudinal axis. This is a classic Snap Roll.

And most obviously a snap roll "looking" maneuver in a Gyro "rotorcraft in an autorotative state" would end badly.

Oh, when executing a side slip and maintaining altitude (passing a ground based observer), the added drag requires additional power to be applied; possibly to full power, why is this so inherently dangerous???
Is it that the added power provides the up pitching moment to stall one wing. I did not think we could stall a rotor; per say. Or is it the torque which provides the pitch and roll and we enter a torque over? Are all gyro's subject to this in one degree or another. Or can it be some designs are more prone than others.
I really want to learn something here.
Thanks for the thread!
 

Vance

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My observations of an MTO Sport.

My observations of an MTO Sport.

Sorry, left for a while to go to church.
In the fixed wing world; if we are in a slow flight configuration just slightly above the stall speed. Apply hard rudder to yaw the aircraft and also apply opposite aileron (cross control) and then pull back on the stick to apply a pitching moment up. The aircraft will stall one wing and roll on its longitudinal axis. This is a classic Snap Roll.

And most obviously a snap roll "looking" maneuver in a Gyro "rotorcraft in an autorotative state" would end badly.

Oh, when executing a side slip and maintaining altitude (passing a ground based observer), the added drag requires additional power to be applied; possibly to full power, why is this so inherently dangerous???
Is it that the added power provides the up pitching moment to stall one wing. I did not think we could stall a rotor; per say. Or is it the torque which provides the pitch and roll and we enter a torque over? Are all gyro's subject to this in one degree or another. Or can it be some designs are more prone than others.
I really want to learn something here.
Thanks for the thread!

I think you are nibbling around the same question as I did in post forty seven only in a different way David.

It was my observation that an MTO Sport when slipped tends to lean in the direction of the rotor tilt more than The Predator.

The pilot in command, not Desmon, applied opposite cyclic to manage this uncomanded roll.

It was my observation that when the pilot in command made a rapid addition of throttle we experienced significant torque roll.

My observation may be distorted by my trepidation about this seemingly unnatural response as well as being a poor passenger with control issues.

I imagine that if these two tendencies were combined it would compound the uncomanded roll tendency.

I imagine entering a slip at higher speeds could exacerbate this tendency.

I will not try to explain the why of this.

I hope if these were accurate observations that some of the more technically astute on this forum will attempt to explain the uncomanded roll of the MTO Sport that I observed.

If they were not accurate observations please disregard this post.

Thank you, Vance
 
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