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AR-1 N923DJ Texas 15-12-18

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  • #76
    The Rotor RPM (RRPM) during a flare should go a bit higher. As far as the rotor is concerned, it thinks the weight of the aircraft has gone higher. You could see 1.1 to 1.2 G during a flare and you do.
    Another simple way to see it is that inflow air velocity or volume has gone higher as flare is executed. We are opening the rotor disc to see or eat more air.
    Many people also cite Coriolis effect but for most modern gyroplane rotors, this effect is negligible.
    I would be a bit worried if a gyroplane rotor RPM went lower instead of a bit higher when starting a flare.

    I don't know which 4000 hour CFI agrees that rotor RPM will definitely go lower as flare is executed but let them know that vector diagrams and Nick Lappos completely disagree with them. Let me know how with vector diagrams or by proof in video your RRPM go lower as you start a flare. Something does not add up here.

    Comment


    • #77

      Some thoughts of mine:

      Vance described his landing sequence, that is exactly how I teach students. I find it disconcerting to be coming in at high speed close to the ground.
      What I do during gusty winds is keep the rudder effective by some increased engine RPM and be prepared to go round with power as required.

      Rotor RPM always increases in flare and high G moves. In a heli, this could easily be controlled by the collective. In the Lama, during flares, the goal was to try and increase rotor RPM to get a better cushion effect when pulling collective for touch down.

      In a gyro, there is no collective and hence no direct control in dropping RRPM, and if there is a rapid rise in RRPM close to the ground, it is possible to get into the situation described by Birdy/Doug and even though there may not be a hover, the airflow reversal effects can be pretty drastic. It would be good if this phenomenon is better understood and taught.
      Antony Thomas
      “Learning without thought is labor lost; and thought without learning is perilous”
      ― Confucius

      Comment


      • #78
        Originally posted by thomasant View Post
        Some thoughts of mine:

        Vance described his landing sequence, that is exactly how I teach students. I find it disconcerting to be coming in at high speed close to the ground.
        What I do during gusty winds is keep the rudder effective by some increased engine RPM and be prepared to go round with power as required.

        Rotor RPM always increases in flare and high G moves. In a heli, this could easily be controlled by the collective. In the Lama, during flares, the goal was to try and increase rotor RPM to get a better cushion effect when pulling collective for touch down.

        In a gyro, there is no collective and hence no direct control in dropping RRPM, and if there is a rapid rise in RRPM close to the ground, it is possible to get into the situation described by Birdy/Doug and even though there may not be a hover, the airflow reversal effects can be pretty drastic. It would be good if this phenomenon is better understood and taught.
        Why would you find it disconcerting coming in at a moderately higher airspeed (say half the gust spread) in a gyro, if this would provide some protection from changes in lift close to the ground? With stronger gustier wind conditions this should not result in significantly increased groundspeed. Add to this the ability to effectively use the rotor as a brake on the aircraft during touchdown, I'm still a little puzzled as to why in a gyro one should not follow a similar approach as one would a FW to build in a safety factor.

        Comment


        • #79
          First off, neither I nor my CFI believe or have claimed that RRPM decays at the moment of a roundout/initial flare or a full-flare.
          I never wrote that it did.
          Vance misinterpreted it that way.



          __________
          Why would you find it disconcerting coming in at a moderately higher airspeed (say half the gust spread) in a gyro, if this would provide some protection from changes in lift close to the ground? With stronger gustier wind conditions this should not result in significantly increased groundspeed. Add to this the ability to effectively use the rotor as a brake on the aircraft during touchdown, I'm still a little puzzled as to why in a gyro one should not follow a similar approach as one would a FW to build in a safety factor.
          loftus, you're asking the right questions. Glad to see it.
          We gyro pilots can scrub off excess AS (and thus GS) any time we like.
          We also enjoy powerful rotorwash as a cushion.
          Why not use them both?



          __________
          I find it disconcerting to be coming in at high speed close to the ground.
          thomasant, I agree, so maybe we're not seeing eye to eye about what is "high speed" close to the runway.

          I've been thinking about a rule of thumb for this. Perhaps 1 foot off the deck for every 10mph of groundspeed?
          (I'm speaking of groundspeed because of the imminence of landing, or possibility of being smacked down by wind shear. I'm not conflating GS with AS.)

          So, say, after 60mph GS roundout/initial flare at about 6 feet, adjust power/stick to reach 50mph@5', 40mph@4', 30mph@3', and 20mph@2'.
          Along the way, you will see a slight decay in RRPM, although still in the lower 300s (using my Sport Rotored RAF as an example) and in the flight RRPM range.

          Note: the above is simply a thought experiment to roughly illustrate what I've been trying to describe.
          Please resist the urge to peck it death as if I'm spouting POH doctrine.

          Antony, you reported having 10mph GS at 4 feet, which, IMO, was a bit too high for that speed. Or, a bit too slow for that altitude.
          I'd have felt somewhat vulnerable to downdrafts during those numbers.

          Regarding that, I'm interested to see how Vance will try to reconcile two of his contradictory statements:


          "In my opinion Antony was not smacked into the ground from a down draft because down drafts have nowhere to go as they reach the ground
          and lose their downward velocity well above the surface unless it is a collapsing thunderstorm or a microburst
          ."

          and:

          "My feeling is that a wind shear started the challenge
          [at 4 feet AGL] and several other factors exacerbated the event."

          What, then, is "well above the surface"? 3 feet? 2 feet? According to Vance, it's not as low as 4 feet.



          ___________
          In a gyro, there is no collective and hence no direct control in dropping RRPM, and if there is a rapid rise in RRPM close to the ground,
          it is possible to get into the situation described by Birdy/Doug and even though there may not be a hover, the airflow reversal effects can be pretty drastic.

          With adequate AS, one simply pitches down and increases power to avoid the hover. Keep flying. Keep moving forward at the chosen low altitude.
          Then gradually reduce power with gradual aft stick to time the moment for a nice full-flare and 0-5 mph touchdown.

          I see two different forms of "insurance" when landing during turbulence:

          1) Drop in mostly vertically from the classic 20' roundout/initial flare but with maybe a bit more power for rudder authority.
          (RISK: pancaking in below 5-10 feet from loss of lift and/or downdraft.)

          2) Fly through mostly horizontally after a within-rotorwash roundout, then getting to 1-2 feet in preparation for the full-flare landing.
          (RISK: being involuntarily set down by a strong downdraft with a-higher-than-desired-though-not-necessarily-unsafe groundspeed,)

          As I and others see it, #2 shortens the amount of time in a block of turbulence, and reduces the vertical impact component.
          During either technique, one must pass through what I consider the vulnerable altitude of 3-10 feet.
          I'd rather pass through that with more speed and lower to the deck than technique #1.

          Regards,
          Kolibri
          PP - ASEL complex (Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, SC2), soloed in gliders

          Wasn't happy with my RAF's pitch instability, so I installed a Boyer H-Stab to my great satisfaction!

          "
          When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

          Comment


          • #80
            Fixed wing aircraft always land with significant airspeed (with only speed and altitude storing energy), have a stall condition to avoid before touchdown, and must shed kinetic energy with drag and wheel-braking on the rollout. That stall avoidance is where much of the safety margin comes from. There is no corresponding benefit for an aircraft that has no stall, stores additional energy in the rotor, and is best touched down at the lowest speed possible, shedding most of the energy in the air. (As Igor Sikorsky said, it's better to stop and then land, than to land and then stop.) I always use the rotor as a brake at touchdown, but don't find an advantage in a need to do more braking arising from extra airspeed. I agree that the extra energy you propose isn't huge, but it also isn't terribly helpful.
            What I typically do in strong wind conditions is change my pattern shape, with a base leg closer in. In case of a power failure, penetrating against a wind in a low glide ratio gyroplane is pretty difficult, and can leave one well short of the intended landing spot. The same principle is true of most fixed wing aircraft, but in my experience, they typically penetrate wind on final much better with a little extra speed than a gyro will.

            Comment


            • #81
              From Kolibri's post 71.
              "I see two different forms of "insurance" when landing during turbulence:

              1) Drop in mostly vertically from the classic 20' roundout/initial flare but with maybe a bit more power for rudder authority.
              (RISK: pancaking in below 5-10 feet from loss of lift and/or downdraft.)

              2) Fly through mostly horizontally after a within-rotorwash roundout, flying at 1-2 feet to the full-flare landing.
              (RISK: being involuntarily set down by a strong downdraft with a-higher-than-desired-though-not-necessarily-unsafe groundspeed,)

              As I and others see it, #2 shortens the amount of time in a block of turbulence, and reduces the vertical impact component.
              During either technique, one must pass through what I consider the vulnerable altitude of 3-10 feet.
              I'd rather pass through that with more speed and lower to the deck than technique #1."

              Rotor wash: air turbulence caused by a helicopter rotor.

              Perhaps Kolibri is writing about ground effect.

              The Principals of ground effect according to Wikipedia:
              When an aircraft flies at a ground level approximately at or below the half length of the aircraft's wingspan or helicopter's rotor diameter, there occurs, depending on airfoil and aircraft design, an often noticeable ground effect.

              So a gyroplane with a thirty foot diameter rotor that is ten feet in the air needs to be less than five feet above the ground to experience ground effect.

              In my opinion fling a gyroplane less than five feet above the ground at fifty to sixty knots is dangerous and pointless.

              There is a third option; round out at fifteen feet and land normally with a little more power to enhance rudder authority.

              In my opinion based on my experience flying in strong gusting winds; Kolibri’s method is dangerous and relies on a consistency of conditions that simply don't exist anywhere I fly.

              I have clients try something approaching the Kolibri method in calm winds and quickly abandon it the first time they fly in strong (15kts to 25kts) gusting winds.

              Kolibri's fantasies about the wind and how it affects a gyroplane during a landing are unrelated to what I experience flying in California, Arizona, Utah, Indiana, Wisconsin and Florida.

              I don't understand why a low time gyroplane pilot imagines that they have thought about it enough to invent a new way of landing a gyroplane in strong gusting winds that is safer without trying it.

              I am confident that Kolibri does not have the skill set to land as he describes.

              Try flying the length of the runway at 60kts indicated air speed 50 feet above the ground in strong gusting winds and I suspect you will discover why it is a bad idea to fly at 60kts indicated air speed five feet above the ground.


              Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

              Comment


              • #82
                What Kolibri claims in post 71: "When Vance landed at Victorville during extreme gusts with mountain wave action and rotors off the hangars, he posted that he lost lift from 20' at 30mph AS.
                That placed him right on the H:V line, and little wonder that he barely saved himself with aggressive application of power.
                (From above that 20' while <42mph, he was vertically descending within the hatched no-fly area.)"

                It appears to me that Kolibri exaggerates for the sake of drama.

                What I wrote:

                I asked for a wind check and it was 150 degrees at 28 gusting to 38.

                I slowed to 30kts indicated air speed and made a vertical descent to the ground at the intersection of runway 21 and taxiway Bravo with a little excitement near the end when the wind speed diminished. Touch down was as nice as could be with a burst of power and no forward speed.

                30kts indicated air speed is 34.5 miles per hour and I typically begin my round out at 15 feet and 50kts so I was probably lower when I reached 30kts knots indicated air speed.

                Federal Meterological Handbook No.1 chapter 5:
                5.4.4 Wind Gust. Gusts are indicated by rapid fluctuations in wind speed with a variation of 10 knots or more between peaks and lulls. The speed of a gust shall be the maximum instantaneous wind speed.

                A ten knot gust is only a barely reportable gust, hardly "extreme gusts."







                Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                Comment


                • #83
                  I find it interesting to observe on this thread some references by posters as to what I may have experienced.
                  According to my logbook, I have over 6100 landings by day. I need to remind myself regularly that a gyroplane is not a helicopter, nor an airplane. It is a gyroplane and has its unique characteristics. Airplane pilots sometimes forget that a gyroplane cannot stall, but the rotors can stall if the conditions are right. Helicopter pilots sometimes forget that the gyroplane cannot hover in still air and there is no collective to cushion the landing. The most sobering fact is that a rotating rotor packs a punch unlike any fixed wing even at zero ground speed.
                  For me personally, the landing itself is a non event, except for the accident one. IMHO, there is no point in getting bogged down by the numbers of whether 4 or 5 feet height, or 10 or 15 mph ground speed, or 15 to 20 mph wind speed gusting can make a huge impact on the landing, unless one is ill prepared to deal with a situation which entails a go round.
                  During my accident landing, I was not prepared for a condition that I now believe could have caused an airflow reversal on my rotors unlike any gust or wind shear that I have experienced. What I have since learned from this experience is that aggressive turns and flares close to the ground can cause an over speed of the rotor, and the consequences of that over speeding can cause a situation which may be difficult to handle if close to the ground.
                  Regarding what technique to use for a landing under crosswind or gusting conditions, I believe Fara, Vance and WaspAir have covered the topics which I believe are tried and true.
                  Antony Thomas
                  “Learning without thought is labor lost; and thought without learning is perilous”
                  ― Confucius

                  Comment


                  • #84
                    Antony, if you go through the NTSB accident statistics, you’ll find that nearly all rollovers occur with gyros having rudder/nosewheel coupling.

                    That’s not to say you weren’t the victim of some freakish occurrence but back in the day when I was flying high inertia, tip weighted rotor blades that would thump you down if normal landing procedure was followed, I enjoyed rolling out of a tight turn immediately prior to landing and playing helicopter for a few seconds.

                    High inertia rotor blades such as from a Hughes OH-6 accelerate more slowly than low inertia blades so during the landing flare, more time must be allowed for the blades to accelerate and develop the extra lift to cushion the landing.

                    Pilots often mistake tail heavy blades for high inertia blades. Tail heaviness provides pseudo collective pitch that can also cushion a landing.
                    **************
                    It just occurred to me that when playing helicopter using excess energy from rolling out of a tight turn, the gyro really is helicoptering and if the gyro is too high, the transition back to gyrocoptering might be fairly abrupt, involving a bit of a drop.

                    Comment


                    • #85
                      Originally posted by Kolibri View Post
                      When Vance landed at Victorville during extreme gusts with mountain wave action and rotors off the hangars, he posted that he lost lift from 20' at 30mph AS.
                      That placed him right on the H:V line, and little wonder that he barely saved himself with aggressive application of power.
                      I think you misapprehend the nature of the H-V diagram. The avoid region reflects an unwise energy state for continuous operation, a serious matter especially for climb out and cruise phases of flight (note that I did not say landing phase, for reasons to follow). The underlying theory is that if an unexpected engine failure happened while flying along at the speed and altitude combinations shown, while you are dependent upon the engine to maintain flight, it would be difficult to put the aircraft down safely if a surprise emergency landing became suddenly necessary. But if you are already in the process of landing on short final, already descending, and already at a greatly reduced power setting as is customary on final, while merely clipping the corner of the avoid region for a brief moment, it is not at all the same risk as continuous powered operation there. Moreover, the HV diagram is not intended to address atmospheric surprises such as wind shear, but engine out dangers for those who would otherwise cruise/climb along blithely ignoring risks of power failures. I think you misstate the nature and the severity of the risk faced by Vance when you describe it in HV terms.

                      Comment


                      • #86
                        Originally posted by Kolibri View Post
                        If the gyro is very low to the runway before the full-flare/touchdown, and one is gradually reducing power meanwhile, and there is hardly any settling from 2 feet, what else can RRPM do but decay?
                        The gradual aft stick adds a little bit of load (and thus RRPM), but (unless you balloon) not more than the simultaneous slowing AS decays RRPM.
                        I.e., there is a slight and gradual net loss of RRPM. (Or do you touchdown with cruise AS level of RRPM?)
                        Timed correctly, most of the rotorwash has been dissipated by the time one reaches nearly 0 groundspeed.[/COLOR]
                        Whatever would inspire you to fly along at two feet without any settling? If you want to get farther down the runway, aim farther down, don't aim early and float to it. Otherwise, if that's not what you want, don't stop at two feet, just keep descending and LAND.
                        I teach (and fly) the "roundout" and "flare" as the beginning and end of one uninterrupted continuous process. My face is smiling when I reach a few inches of altitude and zero ground speed at the same time, with a high deck angle, and find myself sitting on the mains (nose up) just a moment later. Between 50 feet and 0 feet I perform no level flight at all. Rotor rpm DOES NOT decrease in this process. The behavior you describe (slight and gradual net loss of RRPM) simply doesn't happen, and makes absolutely no sense from the standpoint of basic physics or from my rather extensive experience.

                        Please use "ground effect" if that is what you mean; your use of "rotorwash" seems to be nonstandard and is confusing.

                        Comment


                        • #87
                          Originally posted by WaspAir View Post
                          I teach (and fly) the "roundout" and "flare" as the beginning and end of one uninterrupted continuous process. My face is smiling when I reach a few inches of altitude and zero ground speed at the same time, with a high deck angle, and find myself sitting on the mains (nose up) just a moment later. Between 50 feet and 0 feet I perform no level flight at all. Rotor rpm DOES NOT decrease in this process. The behavior you describe (slight and gradual net loss of RRPM) simply doesn't happen, and makes absolutely no sense from the standpoint of basic physics or from my rather extensive experience.
                          Therein is the essence of the "Flare" and the term "Happy Landings". I find it hard to understand how anyone could execute a successful flare and landing any other way.



                          "It just occurred to me that when playing helicopter using excess energy from rolling out of a tight turn, the gyro really is helicoptering and if the gyro is too high, the transition back to gyrocoptering might be fairly abrupt, involving a bit of a drop."
                          Thank you Chuck
                          , I appreciate your insight.


                          Well, I guess having to pay for a new set of rotors, prop, etc is the cost of an education. I'm just thankful that I'm alive and in one piece. I shudder at the prospect of what could have been. Dead or hospitalized with serious injuries and untold hospital bills without the ability to work!

                          I hope this thread has given some useful insight. Pointless for folks to continue arguing about anything else in this thread. I actually thank SteveUK for bringing this thread out.




                          Antony Thomas
                          “Learning without thought is labor lost; and thought without learning is perilous”
                          ― Confucius

                          Comment


                          • #88
                            It appears to me that Kolibri exaggerates [my Victorville landing] for the sake of drama.
                            Not really, Vance.
                            Your truncated account here left out the most important thing: when the gust subsided you were at 20 feet, and you barely saved it with the prompt application of power.
                            Here is your own description from another thread:


                            I was making a vertical descent from about 20 feet when the gust went away and dropped us down pretty quickly. I added power and flared aggressively
                            (You'd already rounded out, thus above 20 feet.)
                            Let's be honest: Had that happened a couple of feet lower, or had the gust subsided more, you'd have dropped in hard.
                            What I summarized then I still believe: you were operating at that moment with very little margin for safety.
                            My impression is that you do so more often than you realize.


                            _____
                            So a gyroplane with a thirty foot diameter rotor that is ten feet in the air needs to be less than five feet above the ground to experience ground effect.
                            IIRC, my 30' rotors are not 10' high, but about 9'. Thus, a roundout/initial flare at 6 feet for me is within ground effect. It certainly feels like it.

                            I don't understand why a low time gyroplane pilot imagines that they have thought about it enough to invent a new way of landing a gyroplane in strong gusting winds that is safer without trying it.
                            Real professional of you to implicitly call me a liar, Vance.
                            a) I didn't claim to invent it, and b) I've used it many times.

                            It is axiomatic that flight inertia which is more horizontal than vertical will better handle turbulence, as well as more quickly penetrate a dirty block of air.
                            And the lower to the ground one does so, the less the turbulence and the less drama it can impress upon the aircraft.
                            If, for example, I'm plopped down from 1 foot at 10mph, it's merely a hard landing of slightly involuntarily timing.
                            However, get plopped down from 4 feet . . .

                            But, hey, keep dropping in mostly vertically from your classic 20 foot roundout. You've already admitted to many close calls.



                            I am confident that Kolibri does not have the skill set to land as he describes.
                            I am confident that nobody flying with one-eyed vision has the required depth perception to confidently and consistently roundout/initial flare at 6 feet.
                            For such a pilot, such would indeed probably be a bad idea, or even dangerous.

                            Regarding Vance's calling B.S. on me, I've GoPro videos of my training days in a Calidus rounding out at or below 6 feet.
                            I could do so then in my first several hours of gyro flying. (I was already a PP-ASEL, thus not an ab initio pilot.)
                            Only one time did my CFI Chris Lord ever reach for the stick, and that was when I experimented with rounding out at probably 3 feet.
                            I had already preceded his reaction with ample back stick, and he apologized for nearly adding to it as he thought we might have pancaked in.
                            I apologized for not giving him a heads up that I was going for a bit lower that time.

                            Just to make sure I wasn't misremembering things, I reviewed some of those landings. I was definitely rounding out in ground effect.
                            In fact, I watched the stick dip forward a tiny bit to compensate for the initial cushioning and not balloon up.
                            I.e., instead of using back stick to arrest descent in my roundout, I was using the gyro's ground effect to arrest my descent.
                            The video is also clear enough to carefully see the altimeter at roundout vs. touchdown.

                            So, anybody sufficiently confident that I do not have the skill set to land as I've described, should PM me to place a $$$$ wager on it.
                            I'll install my GoPro and gather some witnesses to also film it from the ground.



                            Try flying the length of the runway at 60kts indicated air speed 50 feet above the ground in strong gusting winds
                            and I suspect you will discover why it is a bad idea to fly at 60kts indicated air speed five feet above the ground.
                            Wow, really? This assertion from a gyro CFI?
                            It's not a
                            "bad idea" because . . . gusts and wind shear are less severe at 5' than 50'.
                            You've said so yourself many times: downdrafts don't reach the ground, they decrease in velocity the lower they go, etc.
                            Ever seen a winds aloft table? Winds are almost always stronger with altitude.

                            Doesn't anybody recall their earliest student pilot landings during gusty crosswinds?
                            On short final at 100 feet being buffeted around, and having the CFI assuage your nervousness with "
                            Don't worry, ride this out, things will settle down once you're lower to the runway."
                            He was right, and I often say the same thing to any nervous passenger during a gusty short final.

                            So, I've NO IDEA why getting quickly low and below much of the turbulence is so controversial here.
                            My CFI can't understand it, either.



                            ___________
                            Please use "ground effect" if that is what you mean; your use of "rotorwash" seems to be nonstandard and is confusing.
                            Fair enough, WaspAir, willco.

                            But if you are already in the process of landing on short final, already descending, and already at a greatly reduced power setting as is customary on final, while merely clipping the corner of the avoid region for a brief moment, it is not at all the same risk as continuous powered operation there. Moreover, the HV diagram is not intended to address atmospheric surprises such as wind shear, but engine out dangers for those who would otherwise cruise/climb along blithely ignoring risks of power failures
                            Yes, I agree with all that.

                            I think you misstate the nature and the severity of the risk faced by Vance when you describe it in HV terms.
                            I disagree. He didn't even lose engine power, but merely experienced a subsided gust, and yet he still nearly crunched in.
                            His own account corroborated what it's like to be right on the H:V line when something unexpected happens.


                            Whatever would inspire you to fly along at two feet without any settling? If you want to get farther down the runway, aim farther down, don't aim early and float to it.
                            Otherwise, if that's not what you want, don't stop at two feet, just keep descending and LAND.
                            I wrote "hardly any" settling.

                            Between 50 feet and 0 feet I perform no level flight at all. Rotor rpm DOES NOT decrease in this process.
                            The behavior you describe (slight and gradual net loss of RRPM) simply doesn't happen, and makes absolutely no sense from the standpoint of basic physics or from my rather extensive experience.
                            During such a vertical descent with no level flight, sure, I agree. In fact, I've already conceded that, as the rotor is consistently loaded.

                            However, during turbulence I've been describing a much flatter descent, with less rotor loading between the roundout/initial flare and the full flare landing.
                            There is very little [additional] rotor loading from 6 feet to 0 feet, but much more reduction in AS. Thus the slight RRPM decay within the lower 300s.
                            Why this is so difficult to accept for some, I don't know. Perhaps I should film it as proof?



                            ____________
                            During my accident landing, I was not prepared for a condition that I now believe could have caused an airflow reversal on my rotors unlike any gust or wind shear that I have experienced. What I have since learned from this experience is that aggressive turns and flares close to the ground can cause an over speed of the rotor, and the consequences of that over speeding can cause a situation which may be difficult to handle if close to the ground.
                            Antony, I've played around with high-G base-final turns and noticed the increased RRPM.
                            However, I've found it to quickly dissipate and RRPM returns to normal values for the AS.
                            I don't recall any base-final overspeeded RRPM lasting into the roundout.

                            Since you didn't describe your flare as anything vigorus, nor mention any ballooning, it's hard for me to envision an oversped rotor from that flare.

                            But, if, now, you've come to believe that when you were at 4 feet and 10mph that you still had some overspeeded RRPM from either your turn or your flare,
                            which then began to decay causing an airflow reversal and sink, then I hope you're correct in your appraisal and have learned what you needed to learn.

                            However, since you're a gyro CFI, I admit to some surprise that this was something you didn't already know.

                            The other thing that surprised me was that you actually closed your eyes before impact.
                            As Bob Hoover was famous for saying,
                            "Fly the aircraft all the way into the crash."
                            I've actually commanded myself to "Aviate! " during dicey moments, and it helps.

                            _____
                            Thanks for everyone's participation; it's been enlightening, and my particular thanks to Antony for sharing his experience here.

                            Safe flying,
                            Kolibri
                            PP - ASEL complex (Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, SC2), soloed in gliders

                            Wasn't happy with my RAF's pitch instability, so I installed a Boyer H-Stab to my great satisfaction!

                            "
                            When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

                            Comment


                            • #89
                              Originally posted by Kolibri View Post
                              During such a vertical descent with no level flight, sure, I agree. In fact, I've already conceded that, as the rotor is consistently loaded.

                              However, during turbulence I've been describing a much flatter descent, with less rotor loading between the roundout/initial flare and the full flare landing.
                              There is very little rotor loading from 6 feet to 0 feet, but much more reduction in AS. Thus the slight RRPM decay within the lower 300s.
                              Why this is so difficult to accept for some, I don't know. Perhaps I should film it as proof?[/COLOR]
                              I'll try one last time here.

                              First, for clarity, I did not advocate any "vertical descent" in my description of continuous uninterrupted roundout and flare without intervening level flight. An approach with a 4:1 glide is about 14 degrees from horizontal. An airplane pilot used to long 3 degree VASI approaches (19:1 glide) would find it steep, but rotorcraft pilots don't.

                              I strongly suggest that the time between 6 feet and 0 feet is exactly when the rotor loading should be highest.

                              If you want to avoid getting tossed around, put the thing down; don't prolong the hazards or fly through more air when you don't need to.

                              Comment


                              • #90
                                First, for clarity, I did not advocate any "vertical descent" in my description of continuous uninterrupted roundout and flare without intervening level flight.
                                WaspAir, regardless of what you advocate, vertical descent seemed exactly what you described:

                                Between 50 feet and 0 feet I perform no level flight at all. Rotor rpm DOES NOT decrease in this process.

                                __________
                                If you want to avoid getting tossed around, put the thing down; don't prolong the hazards or fly through more air when you don't need to.
                                You seem to be imagining that I'm floating for hundreds of feet. I'm not. I am putting the thing down.

                                It's almost like the FW technique of "
                                flying it to the ground" during turbulence.
                                (On the way to 2013 Oshkosh, I recall my FW go-around from Runway 30 at MML, where I flubbed the classic roundout and flare continuum.
                                Winds were variable and gusting, so I tried Runway 2, and that time very deliberately flew it right to the ground with a decent flare touching only the mains.
                                Just watched those videos. They were, back to back, my worst and best FW landings that summer.)

                                Back to gyro landings in turbulence, I get lower more quickly.
                                The hazards are less there. The winds are less severe there.

                                I suspect that my time between roundout and touchdown is also less.
                                In fact, my Calidus training video I just reviewed shows a time interval of 4-5 seconds.
                                How is that prolonging any hazards?

                                Regards,
                                Kolibri
                                PP - ASEL complex (Piper 180, C206, RV-7A), SP - Gyro (Calidus, RAF, SC2), soloed in gliders

                                Wasn't happy with my RAF's pitch instability, so I installed a Boyer H-Stab to my great satisfaction!

                                "
                                When an honest but mistaken man learns of his error, he either ceases to be mistaken -- or he ceases to be honest."

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