A common language shared by divergent cultures can inhibit communication.

C. Beaty

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Takeoff and landing rollovers are primarily confined to gyros with hard linked nose-wheel to rudder coupling and less frequently in gyros with “soft” nose-wheel/rudder coupling.

The only rollover in a Dominator with free castering nosewheel and toe brake steering resulted from a phenomenon called “duck-walk” due to main wheel suspension geometry; a result of excessive tire scrub during a misaligned landing.
 

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"Having flown a stable powered approach, roundout to come level, and float at about 2 feet."
Gyroplane/gyrocopter landing technique & errors (from 1:41-)
Phil, that's what I prefer also, and was pleased to see such in your video.
You may have just missed a recent thread which ended up debating this very point.

However, even if one did not descend so slightly, but kept level for a short distance at 2 feet while bleeding off airspeed,
how is that worse in turbulence than floating down at 14 degrees in a classic gyro descent?

Simple (and yet unanswered) question: when turbulence is present, is it generally stronger at 0-10 feet or at 20-50 feet?
That's been my central point in this entire thread.

During turbulence, I want to negate as much of it as possible by getting lower ASAP.
What turbulence remains will pose less risk because I've nearly no height left to drop from and my strong ground effect acts as cushion/spring against downdraft energy.


The long shallow round out at higher speeds near the ground shown in your video would not be my choice in gusting conditions.
Yes, Vance, because you prefer vertical descents in gusting conditions, e.g., your 2018 Victorville landing with a first-time gyro passenger in variable winds of 30G38.
Glad you pulled that one off when the gust subsided and you had pounce on the throttle to save the touchdown.

Regards,
Kolibri
 

Doug Riley

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I've wrestled a Dominator out of a duck-walk without capsizing, but a successful escape isn't always possible.

I also rolled one over, though, in a situation unrelated to duck-walk. My tandem Dom had a violent nosewheel shimmy early in its career. As a result, I kept the nosewheel off during landing, until it dropped on its own even with the stick back. This technique didn't pay off on a gusty, cross-windy day. The crosswind got under my tipped-back rotor and rolled the gyro over ever so gracefully.

"Flying like a gyro pilot" in my mind means normally holding the nose off until it settles, BUT it also means changing technique when dealing with wind. The better technique when facing wind is to set down without a full flare, and instantly push the stick all the way forward to "kill" the rotor. I couldn't do that with my Dom until I found the nosewheel swivel friction collar.

In this type of landing, you should have very low ground speed because of the wind, but clearly it's better not to have the nosewheel linked to the rudder pedals. Either differential braking (a la the Dominator) or un-linked nosewheel steering (a la Bensen) is more wholesome. It's likely that only someone who "flies like a gyro pilot" would appreciate why.

All the obsession in the fixed-wing world with V-numbers has to do with the lethal danger of stalling. Gyros fly (or not) based on rotor RPM first, and airspeed second. Fortunately, rotor RPM is so well indicated by control pressures (in the classic offset gimbal head) that a rotor tach is pretty redundant. A quick look at airspeed on takeoff is enough to keep you off the backside of the power curve.
 

C. Beaty

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Another reason rollovers are so rare in a Dominator is the tall tail.

In the case of a gyro with the tail dipping in the lower half of the whirlwind coming off the prop, a last minute throttle blip to save a botched landing will jerk the gyro sideways.

A tall tail eliminates the throttle-yaw coupling.
 

Philbennett

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jm-urbani;n1142042 said:
they land gyros with engine power, they gradually reduce rpm during their flare until they touch the wheels with ground speed .. and there are roll overs ..

Quite aside from the fact the technique you highlight isn't one being promoted by anyone in this thread. One assumes the use of power is nothing more than a method of getting to a particular point more efficiently than being at idle for..how long??

However once more can I get a reference to the accidents you are suggesting happen? Additionally can you show how these roll overs are due to something that relates to what is being discussed?

I completely agree that gyroplanes will roll over because the pilot has touchdown with poor yaw control but poor yaw control is just that. Yes if the pilot approaches on a reasonable power setting and chops the power to land that will promote a yaw change - but nobody is suggesting that is a good idea! So aren't we creating an argument nobody is actually having?

I think you discussed via my YouTube channel about take offs and again I wonder if you could illuminate the issue:-

jean michel Urbani

i will never ever apply full power without stick fully back, never, and i never wait for front wheel to lift before pushing bak the stick, i just wait fort the front wheel to get lighter and i put the stick ahead
also i will never fly an autogyro, the v shape keel allows the gyro to lift it nose too high making possible all those accidents you show , there are no magnis or doms only ela or autogyros
with a magni if you put too much power too early the tail wheel will touch at only 12 degrees and the gyro won’t take off , it is idiot proof

Gyrocopter flying club

Ref: 100% power and stick position. Would you expand your own thinking? What is your rational?

If you look at this video [which gives more in cockpit detail] you will see the technique you advocate verse the new thinking and I can only see upside. But happy to have it explained otherwise.

Usually however the objections can not be explained! However on the flipside I can explain a lot of reason not to use the technique you use.

No.1 is that it is fundamentally inefficient aerodynamically as keeping full back stick means you are in a very draggy state for longer.

No.2 Keeping the stick fully back does not accelerate the rotor to flying speed any faster. [so now we have the situation where you are not building rotor speed nor are you building airspeed as efficiently which is a compromise to taking off].

No.3 Once you get to a position that unstick is possible because you have been in a state of high drag you also have little acceleration such that at unstick you are almost starting the acceleration phase in order to get to a climb speed outside of the H/V curve.

No.4 An additional consequence of No.1 & No.3 is that at unstick the aircraft will yaw and roll more because the tailplane is not working as efficiently.


I do agree with your point on the straight keel of the Magni design that it does not encourage over rotation (for what of a better phrase) but that only cures over rotation it does not solve all of the points above which are primarily about drag and inefficiency. Neither does it help those who are determined to force the aircraft into the air within the H/V curve - just see the M24 pilot at 2m 20sec! Aircraft are very far from idiot proof.
 

Philbennett

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jm-urbani;n1142046 said:
if you don't like coments on your you tube disable them, I don't promote anything... I have nothing to sell .

I enjoy the comments and if you read my reply im inviting you to comment some more to tell me about the technique you use.

Im not selling anything either.

Or you could give a view on why all your landings need to be from the glide to a spot landing.
 

Doug Riley

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JM -- I have some hundreds of hours in an Air Command, including landing on unprepared surfaces.

Yes, the link between the pedals and the nosewheel is soft -- but the nose still will turn abruptly when it touches the ground while the pilot is holding rudder. Maybe it's possible to use even softer springs. The centering force is pretty weak.

The original Bensen B-8M's nosewheel assembly was a massive thing, made of a 3/16" thick steel baseplate and a fork bent from the same material. It had tremendous surface area to create anti-shimmy friction and about 3" of "trail" to provide a centering force. Nosewheel steering was completely separate from the rudder pedals. It was more difficult to master initially, but it eliminated the unintended "swerve" on landing that has apparently caused rollovers. The nosewheel steering was done with the heels of your foot, so that the rotation of your foot on the footrest was the same for a given direction of turn, whether using the pedals or the nosewheel; steering bar.

Bensen later bowed to customer preference and provided a soft link between pedals and nosewheel.
 

Philbennett

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Hello Jean Michel - as I said the comments are welcome and I don't assume to know everything so I'm happy to share ideas.

That said if we talk about something being "dangerous" then I think it is fair to ask for the reason why - and I don't see any explanation around why you think it is dangerous, you merely proclaim that it is.

It is also clear that we are talking at crossed purposes. As an instructor in the UK my work and experience is inevitably in 2 seat aircraft (all Auto-Gyro and Magni aircraft) where you are perhaps relating issues that concern single seat aircraft?

The point is the most popular aircraft have keels that do allow over rotation so it is essential to be mindful of this issue. It is also important to put things into the correct context, in the UK typically pilots become licence holders after 40-50hours of total time and 10hours P1. So we are talking about very new and inexperienced pilots. That we all might be able to "wheel balance" during a take off for the entire runway OR that we maybe able to do consistent spot landings to a point at will is irrelevant. We may have multiple 1000's of hours. It is not the same and the accident data suggests that this aircraft type has, by a significant margin, more accidents than any other class. Interestingly these accidents are also quite unique to the class in that the majority happen in take offs and landing (and actually I don't know of a single UK accident with a gyroplane of CFIT in poor weather - which is a common aeroplane / helicopter accident type).

So my point is the current established thinking is not looking after people very well. As you say - you practice glide approaches for the time your motor stops. I don't know what motor you have and perhaps if its a usual 2 stroke motor found in single seaters that might be valid. However most 2 seat types use a Rotax 9 series motor and they are significantly more reliable, indeed I could not think of more than a handful that have failed in a UK gyroplane EVER. And remember if we fly an approach even with power and the motor stops we just land short, likely still inside the airfield boundary or the field on its approach. It really isn't a huge deal. But making everything a glide approach means you don't fit well in the circuit pattern as you are not easily visible and you are slow. Then it also makes the roundout harder work for the (remember the context) our 10hours P1 pilot, who now has 1 bite of the cherry, which when he fails to take it well starts grabbing at the power....that creates yaw....then they roll over... That is exactly what we see..

In this situation I ask myself - I have my student for a period of time, is it more important to give him a technique that looks after him for the 99% of his flying time than a technique that is useful in the 1%? Going for the 99% just seems an intelligent thing to do?

Finally you use the term behind the power curve. This is a poor term for the one you really want which is behind the drag curve.
 

C. Beaty

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Doug Riley;n1142051 said:
JM --

Bensen later bowed to customer preference and provided a soft link between pedals and nosewheel.
Bensen’s footpeg nosewheel steering never bothered me in the least Doug, since the first vehicle I operated was a tricycle which steered the same way. In fact, when first learning to fly a gyro, the rudder pedals seemed backwards and I seriously considered crossing the rudder cables just as the Wright Brothers had done.

The Wrights were bicycle riders so crossing the rudder cables and making the rudder bar move in the same direction as bicycle handlebars was the natural thing for them.

Glen Curtis came along and taught himself to fly without crossing the rudder cables and that’s the way it’s been ever since.
 

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Philbennett;n1142086 said:
Finally you use the term behind the power curve. This is a poor term for the one you really want which is behind the drag curve.


From the FAA Rotorcraft Flying Handbook, Flight at slow speeds: "Like airplanes, gyroplanes have a specific amount of power that is required for flight at various airspeeds, and a fixed amount of power available from the engine. This data can be charted in a graph format. [Figure 20-13] The lowest point of the power required curve represents the speed at which the gyroplane will fly in level flight while using the least amount of power. To fly faster than this speed, or slower, requires more power. While practicing slow flight in a gyroplane, you will likely be operating in the performance realm on the chart that is left of the minimum power required speed. This is often referred to as the “backside of the power curve,” or flying “behind the power curve.” At these speeds, as pitch is increased to slow the gyroplane, more and more power is required to maintain level flight. At the point where maximum power available is being used, no further reduction in airspeed is possible without initiating a descent. This speed is referred to as the minimum level flight speed. Because there is no excess power available for acceleration, recovery from minimum level flight speed requires lowering the nose of the gyroplane and using altitude to regain airspeed. For this reason, it is essential to practice slow flight at altitudes that allow sufficient height for a safe recovery. Unintentionally flying a gyroplane on the backside of the power curve during approach and landing can be extremely hazardous. Should a go-around become necessary, sufficient altitude to regain airspeed and initiate a climb may not be available, and ground contact may be unavoidable."

The Rotorcraft Flying Handbook is the primary text in combination with the FAR/AIM that is used for knowledge tests and oral tests for gyroplanes in the USA.

I feel this is a good example of common language shared by divergent cultures inhibiting communication.

In the USA behind the power curve would be correct and behind the drag curve is not used in any of our FAA texts.

I tried to find "behind the drag curve" on Google which tends to be more international and was not successful.

JM Urbani's first language is French compounding the challenge. He is kind enough to translate French to English so we can more easily understand on this USA based Rotary Wing Forum.
 

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Yet the curve drawn and the rational related by you and written by the FAA is of course nothing more than total drag. In explaining the effect you will talk of drag. Furthermore the term "flying behind the...curve" relates to airspeed that falls to the left of the total drag curve (as it is not a linear curve). Your power curve is not related to aurspeed but engine RPMs and i can not articulate how you fly to the left of that curve.

if the FAA cant do so that is hardly an excuse to repeat the error. Normalisation of deviance.
 

C. Beaty

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This chart from the Bensen manual shows power required vs airspeed.

In this example, minimum power occurs at 35 mph and flying either faster or more slowly requires more power.

It seems to me that flying more slowly than 35 mph can logically be called the backside of the power curve, whatever variety of English one speaks.

The negative slope makes that portion of the power curve slower than 35 mph an unstable region, requiring constant throttle/pitch manipulation to hold a constant speed.
power curve.JPG
 

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Philbennett;n1142090 said:
Yet the curve drawn and the rational related by you and written by the FAA is of course nothing more than total drag. In explaining the effect you will talk of drag. Furthermore the term "flying behind the...curve" relates to airspeed that falls to the left of the total drag curve (as it is not a linear curve). Your power curve is not related to aurspeed but engine RPMs and i can not articulate how you fly to the left of that curve.

if the FAA cant do so that is hardly an excuse to repeat the error. Normalisation of deviance.

For language to work for communication; definitions understood by both parties are required.

As you can see from the Rotorcraft Flying Handbook behind the power curve has nothing to do with engine rpm and everything to do with power required.

In my opinion not rejecting accepted phraseology and inventing your own definition for a phrase does not make everyone who does not share your perception wrong.
 

Philbennett

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For language to work for communication; definitions understood by both parties are required.
As you can see from the Rotorcraft Flying Handbook behind the power curve has nothing to do with engine rpm and everything to do with power required.
In my opinion not rejecting accepted phraseology and inventing your own definition for a phrase does not make everyone who does not share your perception wrong.

First of all I've not rejected the accepted phase - what I'm picking up on is the lazy application of language and the use of a term that describes one thing miss applied to something else.

That the FAA have it in a handbook still doesn't make it right. You have just added a new element which has not been used before and that is power REQUIRED. But that is absolutely NOT the same as the power CURVE. Neither is the power curve attached to the post by C Beaty accurate as since when does horsepower at full throttle vary to that extent with airspeed?

One might accept that at the margin with a fixed pitch prop the engine RPMs will change but I do not believe that at the 35mph engine horsepower at full throttle is that low. That graph is utter nonsense, attached is the actual power curve for the 912ULS motor and that will show that 100% throttle would give circa 5800rpm and 100hp, showing very much that power has everything to do with engine RPM.

What we might be saying is that the FAA handbook has created a term that is as you quoted before which is this:-

[QUOTE
This data can be charted in a graph format. [Figure 20-13] The lowest point of the power required curve represents the speed at which the gyroplane will fly in level flight while using the least amount of power. To fly faster than this speed, or slower, requires more power. While practicing slow flight in a gyroplane, you will likely be operating in the performance realm on the chart that is left of the minimum power required speed. This is often referred to as the “backside of the power curve,” or flying “behind the power curve.”
][/QUOTE]

So as we all agree that language is important then it follows that we can not be lazy and we must put our term in the correct CONTEXT. Hence the highlighting of the FAA use where they DO put the term in the correct context of what they mean. Just rolling out the term in a lazy manner - again to student who might not know any better - is why people make mistakes.

Therefore if we put all this in the context of what has been written here. Jean Michel used the phase behind the power curve when describing a take off accident. That is not in the same context of how the FAA are using their phrase. At take off one hopes we all agree it is done at 100% throttle and therefore 100% power. These accidents occur NOT because they were flying at <100% power and failed to recognise that they needed more power to fly slowly (as per the FAA message) BUT because in the desperation to climb they over pitch and are very definitely flying behind the drag curve.

The use of the FAA's definition of flight behind the power curve should only apply to slow flight because it is their attempt to highlight how you need - in some circumstances- as much power to fly slowly as more quickly.

It maybe nuanced but it is important to be accurate.
 

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C. Beaty

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Power equals force x velocity. James Watt, based on measurements obtained from Welsh mine ponies pulling coal carts, reckoned one HP to be 550 ft-lb/second.

No matter how much much force is applied to a stationary object, zero power is received by that object.

If a 550 lb. gorilla could climb a rope at the rate of 1 ft/sec, we would have a 1 hp ape. Simply sitting on his hind end, he would be exerting a force of 550 lb against the floor but delivering zero power.

Bensen’s power curve is exactly that; if drag needs to be known at any speed, take the power required at that speed, multiply by 550 and divide by velocity, fps.

For example, if drag at 60 mph (88fps) needs to be known, take power required, say 30 hp, multiply by 550, divide by 88 and we have 187.5 lb of drag.

Any misunderstandings about this subject have nothing to do with language variations and everything to do with the understanding of elementary physics.
 

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and how is any of that relevant to the graph which has a curve labelled "engine power available at full throttle" verse airspeed? If one puts full throttle at zero airspeed is engine power not available?
 

Philbennett

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I think this nonsense has everything to do with language and dear oh dear some have accepted these poor terms for so long they can not see the woods for the trees.

The power made by the engine is graphed as per the Rotax item in post 38. That is a typical power curve. Now you might describe other things but when you talk about an engines "power curve" not power required curve or power available curve BUT power curve then it looks like the Rotax curve. Any other derivative should be described and applied in its correct context.

The Bensen graph - without seeing any other description or article where that graph is referenced the basic labelling is poor. The dashed line labelled "Engine power available at full throttle" is firmly at zero when airspeed is at zero. That is nonsense.
 

Philbennett

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jm-urbani;n1142105 said:
phil , again if you fly a magni, or my gyro and apply full throttle stick back without pushing the stick early enough to prevent the front wheel to lift too much, the gyro will lift it's nose but , as the tail wheel is low the gyro won't take off ( we can do the test together anytime you want) .. you will be forced to push the stick ahead to take off, it is idiot proof, no need to release the brakes stick ahead or partially ahead fo 4 seconds to avoid getting behind the power curve or to avoid you blades to touch the ground behind you which is dangerous in my opinion and in my instructor opinion ( planet gyro montelimar, all them and speak about it with them)
I have 2 friends who were used to do what you advise folks to do and the ended up pulling the stick to late and the both flapped their blades and destroyed their gyro

Hey JM - I think its a matter of understanding or having the technique demonstrated. As I said if you have (in a MTO or Magni) 220RRPM and positively increasing from that it is impossible to flap the blades putting the stick 1-2x fist width forward. Simply impossible. The guys that destroyed their aircraft did not do so in the conditions I describe.
 

C. Beaty

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Power equals force x velocity, no matter which language.

Power may also be defined as the rate of doing work.

A stationary object, no matter how much force is applied, receives zero power.

A gyro tied to a tree with engine going flat out receives zero power.

The tree receives zero power as long as it remains stationary.

The 100 or so HP the engine applies to the propeller churns the air but applies zero power to the gyro.

This confusion is not a matter of language; it is the result of a lack of understanding of elementary physics.
************************

Wikipedia has good explanation of power:

https://en.wikipedia.org/wiki/Power_(physics)
 

Philbennett

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jm-urbani;n1142115 said:
yes he did I saw it myself, when he realised he had not yet pulled his stick he was already too fast he tried to pull his stick and flapped his blades , a consequence of the bad method you are discribing, still in my opnion but you are an instructor not me .

So that isn't a technique promoted by me... We have been spinning our wheels over a none event. My technique starts with the stick fully back, etc. Watch it and learn.

https://youtu.be/kW65IY39MPU

The 100 or so HP the engine applies to the propeller churns the air but applies zero power to the gyro.

This confusion is not a matter of language; it is the result of a lack of understanding of elementary physics.

Again we are arguing a different point. The engine as you now concede is making 100HP which it is applying to the prop. The label on your graph references engine and available power.

How is that 100HP that is churning the prop NOT AVAILABLE?? Enough semantics.
 
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