Blade Sailing

[rtrhd]

Twin Lakes (S17)
Kent Sapp
Just moved there from Northern California. I'm not instructing presently but I may when my M2 gets delivered/built. I'm on the production wait list.
I am a gyroplane CFI

 

[Burrengyro]

Interesting comments by the many experienced CFI's here on touch-and-go's etc., with reference to rotor rpms. I agree with this safe training approach. If I intend to do a touch-and-go, I sometimes deliberately approach the runway too high and do some sharp "S" turns to lose height but also to spin up the rotor as much as possible to land softly on the mains without losing too much rotor rpm. Once the nose touches down, I bring the stick back and roll on the throttle to immediately commence a take-off. This method reduces rotor rpm decay to a minimum. (I can see the usefulness of the GWS here.)

If I am on finals to land and decide that my approach is such that I will not touch down and stop at a planned point on the runway, be it the numbers or just before the runway exit, I prefer to abort my approach and at about 2 ft over the runway, I accelerate to best climb speed and go around to approach again. Of course, weather and wind direction must be considered and radio my intentions............

I am happy to be corrected if it prevents cock-ups for me or anybody else. Continuous training, learning, and loads of practice to maintain currency helps a lot.

 

[Vance]

I have heard of flight instructors recommend sharp S turns to speed the rotor up in a gyroplane before landing.

I have tried it and the increased rotor rpm does not seem to last till touchdown.

I feel it is possible to make a very gentle touch down simply by using the rotor rpm from the round out.

If there is a way for me to get the S turns to work I would love to try it.

Apparently I am not doing it correctly.

 

[Burrengyro]

Hi Vance and Abid,
I agree with your comments. With your huge and busy runways all over the USA, doing this sort of manoeuvre might not be appreciated by the control tower and others in the circuit might wonder what you are doing, especially fixed wings. On our short narrow grass runway, with very little traffic, I make the final turn only a few meters from the threshold. It works well with the heavier composite rotors on the ELA. One of my CFI's told me it is better to fly a low powered approach similar to fixed wings so the fixed wing pilots understand what the gyro is doing, especially at airports mainly used by fixed wings. I have to admit, doing sharp S turns is really practice for emergency landings in rough fields so that I can touch down in a tight space. Everything is dependent on the wind conditions. I envy the runway facilities you enjoy in the USA.

 

[Abid]

Hi Vance and Abid,
I agree with your comments. With your huge and busy runways all over the USA, doing this sort of manoeuvre might not be appreciated by the control tower and others in the circuit might wonder what you are doing, especially fixed wings. On our short narrow grass runway, with very little traffic, I make the final turn only a few meters from the threshold. It works well with the heavier composite rotors on the ELA. One of my CFI's told me it is better to fly a low powered approach similar to fixed wings so the fixed wing pilots understand what the gyro is doing, especially at airports mainly used by fixed wings. I have to admit, doing sharp S turns is really practice for emergency landings in rough fields so that I can touch down in a tight space. Everything is dependent on the wind conditions. I envy the runway facilities you enjoy in the USA.

Wait. Why do you use S turns? To lose altitude or to raise rotor RPM.
It’s as useless a maneuver as a hard slip if the goal is to lose altitude because you can simply do a vertical descent in a gyro to an appropriate height.
Raising the rotor RPM will happen but it will go away in a second after becoming level so it doesn’t do anything for actually touching down. You will have the same RRPM as if you flared to land normally. Flaring already raises the G load to about 1.4 to 1.5 and the RRPM are raised in less than a second. Trust me I can show you this with GWS graph data if you want.
You may be doing something not understanding it’s not really necessary.
I can show the data for this if you want. I know a lot of myths abound in the gyro world because there was no measurements done to prove them wrong.

 

[Burrengyro]

Wait. Why do you use S turns? To lose altitude or to raise rotor RPM.
It’s as useless a maneuver as a hard slip if the goal is to lose altitude because you can simply do a vertical descent in a gyro to an appropriate height.
Raising the rotor RPM will happen but it will go away in a second after becoming level so it doesn’t do anything for actually touching down. You will have the same RRPM as if you flared to land normally. Flaring already raises the G load to about 1.4 to 1.5 and the RRPM are raised in less than a second. Trust me I can show you this with GWS graph data if you want.
You may be doing something not understanding it’s not really necessary.
I can show the data for this if you want. I know a lot of myths abound in the gyro world because there was no measurements done to prove them wrong.

Hi Abid, Why do S turns: to shorten the distance from where you are now to the point at which you want to land. Of course you could do a zero airspeed descent and lower the nose to gain speed and land also. Doing these types of exercises is part of the fun of flying gyros. I definitely get some rotor rpm speed up and because I land within seconds of this rrpm gain, I get the benefit of a slower softer more precise landing where I planned to land. I defer to your data, if it proves me wrong. The ELA composite blades being heavy are inclined to hold the higher spun-up rrpm for longer. It seems to be useful in low wind conditions. I'm learning so much from this forum I am happy to be found wanting in my understanding if a better explanation is forthcoming. I have to say that the data from your work with Mike G on the GWS is putting real numbers where previously all we had was seat of the pants feelings. Maybe there is more fun in feelings than hard data?

 

[Abid]

Hi Abid, Why do S turns: to shorten the distance from where you are now to the point at which you want to land. Of course you could do a zero airspeed descent and lower the nose to gain speed and land also. Doing these types of exercises is part of the fun of flying gyros. I definitely get some rotor rpm speed up and because I land within seconds of this rrpm gain, I get the benefit of a slower softer more precise landing where I planned to land. I defer to your data, if it proves me wrong. The ELA composite blades being heavy are inclined to hold the higher spun-up rrpm for longer. It seems to be useful in low wind conditions. I'm learning so much from this forum I am happy to be found wanting in my understanding if a better explanation is forthcoming. I have to say that the data from your work with Mike G on the GWS is putting real numbers where previously all we had was seat of the pants feelings. Maybe there is more fun in feelings than hard data?

Ok. Of course you can do S turns for fun.

But trust me your rotor RPM gain due to S turns isn't there. Whatever your rotor RPM gain is at very close to touchdown, its simply due you you pulling stick back to flare. S turns rotor RPM gain at that point is long gone. Rotor RPM gain does not even last multi seconds. It lasts a second in Averso Stella rotor system which is 87 pounds. I really doubt that ELA composite rotors are that different even if they are heavy which they are actually a little lighter than Averso I think. I have flown ELA 07 with their composite rotors for 14 hours and its really not any different. So what I think is true is if you just did a vertical descent to nose down and sped up to 60 knots and then flared properly you will gain the same rotor RPM and touchdown should be the same soft one. You have to get to the same speed (airspeed) as you are with doing S turns. If you are getting to 70 knots instead of 60 then that is what you need to get in a final dive as well without S turns to compare apples to apples.

 

[WaspAir]

I get nervous when people talk about vertical descents in the pattern, especially when it sounds like maybe it's done on final. There should be an H-V diagram with an avoid region in the POH, and it's just as important as the takeoff rotor management section. Mess it up, add a touch of bad luck, and you'll end up in an NTSB report.

Gyros come down like bricks in normal power-off flight anyway (gliding like dead chickens) so there shouldn't be much need for vertical descents in the pattern.

 

[Abid]

I get nervous when people talk about vertical descents in the pattern, especially when it sounds like maybe it's done on final. There should be an H-V diagram with an avoid region in the POH, and it's just as important as the takeoff rotor management section. Mess it up, add a touch of bad luck, and you'll end up in an NTSB report.

Gyros come down like bricks in normal power-off flight anyway (gliding like dead chickens) so there shouldn't be much need for vertical descents in the pattern.

Yes of course. Vertical descent should be done to HV curve limit (usually for all new gyroplanes about 500 feet AGL at zero indicated airspeed) and from there you need to put the nose down and gain airspeed and get to your target speed to flare properly. Sometimes because of separation and coming in closer you can end up at 700 - 800 feet on final here at our airport (we have to fly a 1000 foot pattern). If you want to make the numbers you do a vertical descent. Also its not a maneuver a gyroplane pilot should be afraid of. He needs to understand his HV curve as well and demonstrate that understanding in the checkride somehow. If I see someone do a vertical descent and they are going down to 400 feet at 0 IAS and not pushing nose over yet. I know they don't get it yet.

 

[Burrengyro]

Ok. Of course you can do S turns for fun.

But trust me your rotor RPM gain due to S turns isn't there. Whatever your rotor RPM gain is at very close to touchdown, its simply due you you pulling stick back to flare. S turns rotor RPM gain at that point is long gone. Rotor RPM gain does not even last multi seconds. It lasts a second in Averso Stella rotor system which is 87 pounds. I really doubt that ELA composite rotors are that different even if they are heavy which they are actually a little lighter than Averso I think. I have flown ELA 07 with their composite rotors for 14 hours and its really not any different. So what I think is true is if you just did a vertical descent to nose down and sped up to 60 knots and then flared properly you will gain the same rotor RPM and touchdown should be the same soft one. You have to get to the same speed (airspeed) as you are with doing S turns. If you are getting to 70 knots instead of 60 then that is what you need to get in a final dive as well without S turns to compare apples to apples.

Hi Abid, Appreciate the feedback. I approach landing at 60 mph / 55 knots. I try to make sure rotor rpm does not decay during this phase. When I get my gyro back together I will record the rotor rpm and airspeeds using a Gopro to make sure there is some reality about my post. I appreciate rotor rpm and airspeed clocks may not be as accurate as one would like. I aim for gentle and almost zero meters landing roll on the grass.

 

[Burrengyro]

I get nervous when people talk about vertical descents in the pattern, especially when it sounds like maybe it's done on final. There should be an H-V diagram with an avoid region in the POH, and it's just as important as the takeoff rotor management section. Mess it up, add a touch of bad luck, and you'll end up in an NTSB report.

Gyros come down like bricks in normal power-off flight anyway (gliding like dead chickens) so there shouldn't be much need for vertical descents in the pattern.

Hi Waspair, Agreed! Zero airspeed descents are not good at any airfield used by fixed wings. I prefer a standard glide or low power glide approach so that fixed wing pilots understand what I'm doing. John H.

 

[Tyger]

Zero airspeed descents are not good at any airfield used by fixed wings. I prefer a standard glide or low power glide approach so that fixed wing pilots understand what I'm doing. John H.

Every airfield I have ever flown to is "used by fixed wings".
But I would say for about 98% of my landings none of those aircraft were actually flying nearby (a few busy (usually towered) airports excepted).

 

[WaspAir]

Hi Waspair, Agreed! Zero airspeed descents are not good at any airfield used by fixed wings. I prefer a standard glide or low power glide approach so that fixed wing pilots understand what I'm doing. John H.

If your engine hiccups while you're vertically descending in the HV avoid region, nearby airplanes won't matter (except to provide witnesses for the crash investigation).

 

[Greg Vos]

Hi Abid, Appreciate the feedback. I approach landing at 60 mph / 55 knots. I try to make sure rotor rpm does not decay during this phase. When I get my gyro back together I will record the rotor rpm and airspeeds using a Gopro to make sure there is some reality about my post. I appreciate rotor rpm and airspeed clocks may not be as accurate as one would like. I aim for gentle and almost zero meters landing roll on the grass.

Explain how you have any control over your rotor speed? Some of you confuse me….if you are at the the decision point and your to high come off the power, if your over the threshold you can cut the power a gyro does not need power to land ( it’s a nice to have if you muck it up) hold off and wait for it to gently fall vertically around 200ft agl invite the nose down and land ..it’s a non event and very gentle. Gyroplane is very forgiving if flown correctly and the argument that vertical descents take longer than S turns is IMO incorrect, with a vertical you are already lined up for the target no fussing about getting balance or other influences like the torque from adding or reducing power ….line up power off, correct it with the pedals wait it’s gentle judge height invite nose down …Land simple
as a reference ( we all already know this ) a fixed wing lands at 3 degrees a helicopter approach is around 10 degrees and the safe landing profile for a gyro is 30 degrees

 

[Burrengyro]

Explain how you have any control over your rotor speed? Some of you confuse me….if you are at the the decision point and your to high come off the power, if your over the threshold you can cut the power a gyro does not need power to land ( it’s a nice to have if you muck it up) hold off and wait for it to gently fall vertically around 200ft agl invite the nose down and land ..it’s a non event and very gentle. Gyroplane is very forgiving if flown correctly and the argument that vertical descents take longer than S turns is IMO incorrect, with a vertical you are already lined up for the target no fussing about getting balance or other influences like the torque from adding or reducing power ….line up power off, correct it with the pedals wait it’s gentle judge height invite nose down …Land simple
as a reference ( we all already know this ) a fixed wing lands at 3 degrees a helicopter approach is around 10 degrees and the safe landing profile for a gyro is 30 degrees

Hi Greg, I agree with your points on vertical descents and S turns. No control over rotor speed. However, I can have some influence by doing sharp S turns and flushing air through the rotors. The centrifugal forces generated by the sharp turn flushes more air through the rotors thereby increasing the rotor rpm. I sometimes deliberately increase the length of the base leg so that I have to do a sharp left hand 180 degree correction turn followed by a sharp right hand 90 degree correction turn to align with the runway. This manoeuvre gives me some extra rotor rpm to be able to float in low over the numbers and have enough extra rotor rpm to touch down at low ground speed for a next to zero landing roll to full stop. All this is done with 60mph airspeed and the throttle being closed at the downwind / base leg turn. One of the reasons I use this method is to simulate the practice of landing in a rough field, but at the safer environment of the airfield, should the engine quit. I hope I am making sense? I don't have Gopro footage of my instruments to show data to back up this method like Abid and Mike G show with the GWS. Next time maybe....

Concerning the approach slope: Gyros can do steep approaches and round out touching down to a short ground roll, if required. My examiner in the UK suggested using a similar shallow long approach slope used by fixed wing pilots so that the gyro is more visible in the pattern and is located in a position where fixed wing pilots expect other fixed wings to be as they complete the pattern. He suggested this as a safer pattern etiquette. If an airfield is not busy, then gyros can use any landing technique they choose. Any correctional advice gratefully received. John H

 

[WaspAir]

Pull some g in the final flare just before touchdown if you want some rpm boost at a useful time. Nothing you do in turns on approach will last more than a moment when you roll out (and turning at flare height is a mustering trick for scaring cattle, not a recipe for a good landing).

My A&S18A, with about 200 pounds of rotating mass - far more inertia than any teetering gyro system - won't hold turn-induced rpm boost for any useful period of time.

P.S. Flying a fixed wing pattern compromises safety for "etiquette". You can't glide like a fixed wing, and you'll be unable to make the field when the motor goes quiet.

 

[Tyger]

Pull some g in the final flare just before touchdown if you want some rpm boost at a useful time. Nothing you do in turns on approach will last more than a moment when you roll out .

I quite agree. For me, pulling back the stick and entering a steep descent (when necessary) makes a lot more sense than S-turns and such.
You just need to make sure you start to get some of that airspeed back when you are still a couple of hundred feet up.

 

[Greg Vos]

Hi Greg, I agree with your points on vertical descents and S turns. No control over rotor speed. However, I can have some influence by doing sharp S turns and flushing air through the rotors. The centrifugal forces generated by the sharp turn flushes more air through the rotors thereby increasing the rotor rpm. I sometimes deliberately increase the length of the base leg so that I have to do a sharp left hand 180 degree correction turn followed by a sharp right hand 90 degree correction turn to align with the runway. This manoeuvre gives me some extra rotor rpm to be able to float in low over the numbers and have enough extra rotor rpm to touch down at low ground speed for a next to zero landing roll to full stop. All this is done with 60mph airspeed and the throttle being closed at the downwind / base leg turn. One of the reasons I use this method is to simulate the practice of landing in a rough field, but at the safer environment of the airfield, should the engine quit. I hope I am making sense? I don't have Gopro footage of my instruments to show data to back up this method like Abid and Mike G show with the GWS. Next time maybe....

Concerning the approach slope: Gyros can do steep approaches and round out touching down to a short ground roll, if required. My examiner in the UK suggested using a similar shallow long approach slope used by fixed wing pilots so that the gyro is more visible in the pattern and is located in a position where fixed wing pilots expect other fixed wings to be as they complete the pattern. He suggested this as a safer pattern etiquette. If an airfield is not busy, then gyros can use any landing technique they choose. Any correctional advice gratefully received. John H

Doing sharp S Turns to increase Rrpm has very little purchase.. I think you need a bit of ground school and possibly some time with a different instructor … yes in a high G loaded turn you will see a brief increase in Rrpm ( let’s go back to the basics) that said as you level out that increase will be lost in the blink of a eye

To understand the value of Rrpm and lift please search this forum for the debate or Rrpm and take off distance ..( high pretotation) you will be surprised how that small increase in Rrpm you claim you have on touch down versus the normal Rrpm you exp during flight is such an advantage.

As for your instructor saying a shallow app will make you more visable in the circuit ? Now this gets my attention as it goes against the basics of Gyroplane flying, a gyro is not a Fw and therefore a 3degree approach is risky for a number of reasons ( separate debate) …the correct method is 30 degrees and possibly our instructor needs instruction
Did this instructor not mention spacial awareness and communication make one visible in the circuit pattern …. Eg: this is XYZ left hand down wind Runway then add number 1 or number 2 ….this is XYZ left base Runway xxx we all appreciate visual contact is nice but it’s not unreasonable to get a mental pic of who is where ,…when you call Final approach Runaway XYZ then it’s up to other aircraft and pilots to identify your position because they are expecting you on final approach ….just my comments

 

[Burrengyro]

Hi Folks, Many thanks for the advice and feedback. Greg, the instructor held the opinion that many fixed-wing pilots approach using long finals. Regardless of calls to the tower or local traffic, gyros are small and often hard to see. His idea was to fit in with what the general fixed-wing pilot is familiar with rather than do what gyro pilots can do which, as we know, is alien to the former. So if we want to fly in the same space as the crows, we may need to fly like the crows until we are out of their way. Then we can fly like gyro pilots.

Some say doing S turns is of little value with respect to increasing the rotor rpms. This might well be true. I have landed and stopped before the rrpm increase has decayed. On days with little wind, it has some merit. I need to get some recorded data to substantiate my theory. Hopefully this summer. Practicing doing the S turns as part of a landing routine in different wind conditions may prove useful when an emergency landing has to be carried out if the engine fails. I don't want to give the impression that this should be standard landing practice. I use all gyro landing methods on a regular basis to stay as fresh as possible, including landing in the center of the runway in strong cross wings. It's the takeoffs in strong crosswinds I find can be a problem.

 

[WaspAir]

A gyroplane cannot perform like a "crow" and shouldn't be flown like one.

Your first obligation is to operate your own aircraft safely, and following a fixed wing pattern isn't safe. You must be able to reach the chosen field/runway from any leg of the pattern if the engine fails. That means adapting your pattern to the characteristics of the aircraft in use. Airliners fly enormous patterns at high speed, twins fly bigger and faster patterns than single engine airplanes, and gyros need to fly patterns that suit their lower speed and steeper glide. Anything else risks crashing into trees short of the runway.

If you want to fit in and be seen, fly a lower, closer, slower pattern that takes about the same time to complete, and puts you in the sight line of a fixed wing pilot looking toward the runway from his higher wider path. Use your radio, landing light, transponder, and strobes if you have them.

Autorotation provides stable rpm through balance of the forces from driving and driven regions. As soon as you reduce to 1 g in the rollout from your s-turns, the rpm IMMEDIATELY drops to the prior stable value. You are fooling yourself if you perceive differently.

I would seek out a different instructor than the one who has been advising you.