Announcement

Collapse
No announcement yet.

Unbalanced sportcopter blades

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #46
    Mike, I'd noticed the 2004 vs. 2012 discrepancy, but didn't know the history of Gyro-Tech. It seemed a "previous owner" kind of thing.
    Good news that the Polish company was not the subject of that AD back in 2004.

    I'd like to see some photos of G-T's hub bar and rotorhead. I've found a few grainy ones online, and their website is a bit sparse.

    Regards, Kolibri

    PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

    "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

    Comment


    • #47
      Kolibri, perhaps an apology to the Polish Gyro Tech is in order, you implied they had a failure and that wasn't true hence their reputation could have suffered, as could SportCopters after Eddies comments and you thought that that merited an apology.



      It seems we have a number of Gyro Techs

      Gyro Tech in Poland making the carbon blades we're discussing here.

      Gyro Tech subject of the ASRA directive covering delamination.

      Gyro Tech in US with, perhaps, Tim Blackwell

      Gyro Tec in Germany who make the very nice single seat DF-02 http://www.gyrotec.de/

      Perhaps an unfortunate choice of company name.

      Mike G

      Comment


      • #48
        Mike, thanks for your support and understanding.
        Best Regards,
        Eddie Sigman,Polvadera,nm
        (575) 835-4921

        Comment


        • #49
          Kolibri, perhaps an apology to the Polish Gyro Tech is in order, you implied they had a failure and that wasn't true hence their reputation could have suffered, as could SportCopters after Eddies comments and you thought that that merited an apology.

          It seems we have a number of Gyro Techs

          Gyro Tech in Poland making the carbon blades we're discussing here.

          Gyro Tech subject of the ASRA directive covering delamination.

          Gyro Tech in US with, perhaps, Tim Blackwell

          Gyro Tec in Germany who make the very nice single seat DF-02

          Perhaps an unfortunate choice of company name.
          Sure, Mike, that's a fair point. My apologies to Gyro-Tech of Poland for unintentionally misconflating the 2004 AD with them.

          Regards, Kolibri

          PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

          "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

          Comment


          • #50
            Why will Eddie need more prerotation RPM if he goes with the shorter blades?
            Oh, btw, just in case the answer wasn't obvious to anyone else but Vance,
            I'll begin with his own quote from the Rotorcraft Flying Handbook:



            More advanced gyroplanes use a prerotator, which provides a mechanical means to spin the rotor. Many prerotators are capable of only achieving a portion of the speed necessary for flight; the remainder is gained by taxiing or during the takeoff roll.
            A "portion" means a percentage. A particular gyro's prerotator proportionality (i.e., xx% of takeoff RRPM) remains more or less constant, and if takeoff RRPM is increased, then so is prerotational RRPM.


            I suspect a smaller disk will have a higher flight rpm.
            Then, that gyro's prerotation RPM will be correspondingly higher because the same p/r horsepower available to the ring gear is now spooling up a lighter rotor disk.

            This is what I meant in my post #16 by "[a 28' rotor] will require significantly more prerotation RPM for take-off [than a 30' rotor]".



            It is my observation a higher rotor RPM in flight has nothing to do with the pre-rotation speed [of ~80 RRPM] required for the blades to become stable.
            I never limited my remark to some minimum prerotational RRPM for stability.
            Most pilots spool up much higher than that to shorten the takeoff roll, and it was in such obvious context that I wrote what I did.

            Even from my older RAF, its p/r can manage (depending on how recently serviced it is) 180-202 RRPM. I usually begin my takeoff rolls at 150-170.



            Gyro-Tech's web page says maximum length of the blades is 4 meters.
            I went to the Gyro-Tec website because the information in your original post seemed flawed; turns out it was.
            Turns out it wasn't. The modified 8H12 airfoil blades which can be made up to 4m in length are
            (according to their website) only 8" chord and perform only to a
            "maximum flight speed is 120-130 km/h"
            and thus unsuitable for a 1320lb. RAF of 200+hp. This leaves the original 8H12 airfoil blades of 3.85m max length.


            __________
            One of the advantages of using carbon-fiber for rotor blades is that complex 3-D shapes are possible (vs. only 2-D for extruded aluminum).
            Gyro-Tech's current rotors have no such complex shape, and also use the very dated NACA 8H12. ???
            In another thread about other rotors, Chuck Beaty commented on this airfoil:


            The thing that puzzles me is why they should select a failed 1940s helicopter airfoil (NACA 8H12) that Bensen picked for ease of hand starting. There are a number of modern rotorcraft airfoils that offer better lift/drag ratios.
            The French ONERA OA-212 airfoil is one of several modern rotorcraft airfoils that offers improved performance over an obsolete NACA 8H12.
            The 8H12 was designed by NACA in the 1940s with the hope of improving the performance of early helicopters. It did not, based on the whirl tower test listed above and no farther testing was conducted. There is no high speed data for the 8H12.

            Bensen picked the 8H12 for its flat stall and resulting ease of hand starting. It has become the standard rotor airfoil for amatuer gyro designers.
            ____________
            Instead of ordering (originally, or subsequently as SC and I and others had long recommended) an SC rotorhead which would have solved his vibration issue, he monkeyed around with the SC rotors by eventually adding "6"s of 3/32" diameter lead solder wire in one blade". (!) Then he fashioned a shimmy dampener from $25 parts. Finally, he had the idea of swapping out RAF rotorheads.

            Put another way, even after installing the SC rotors, his RAF still had "dandruff" (i.e., the OEM rotorhead). Instead of buying some "Head & Shoulders shampoo" (an SC rotorhead), he made himself a "tweed coat" (shimmy dampener) to mask the dandruff.

            If, as I suspect, Gyro-Tech is also supplying eddie with a new rotorhead with their blades, then I hope he will have the grace not make a specious "apples to oranges" comparison about how much "smoother" they are vs. his SC rotors in that unbalanced RAF rotorhead.

            Why not throw your G-T blades in his (least worst) RAF rotorhead as a first step? That would be interesting.

            As far as new owners of G-T rotors go, this is the only comment I've so far found on RWF, from July 2016:


            Spent a full day balancing & tracking blades , getting close to being acceptable ......maybe half a day again tomorrow fine tuning. Certainly weren't 'ready to fly' as claimed on website.

            Only my opinion but I think the design has a little too much reflex on trailing edge. There is no actual fittings to allow string lining blades ....I just used two 6mm allen keys in cap head bolts in end of blade with the string line tied to them . It would have been maybe half an inch out initially .....but a few gentle taps ( bashed it with a block of wood & a hammer ) got it aligned.
            (Kolibri NOTE: This was Hosko's last post on the subject.)


            ____________
            I look forward to your report, Dave.

            What facts did eddie have in mind when he wrote ď
            the polish machining,craftsmanship,engineering and quality products are second to noneĒ?

            I donít know what that means or how Gyro-Tech supposedly achieves it.
            Their website claims, "
            We use composite fiber that makes our blades very light, durable and stiff."

            I donít recall having a problem with my gyroplane rotor blades not being stiff enough and it is my opinion
            that some blade flex can be good for stability and ride quality.

            Please understand I am not denigrating the blades; I have not seen them or flown them.

            I am trying to understand the superiority of these blades as publicized by eddie.

            Regards, Kolibri
            Last edited by Kolibri; 11-14-2017, 10:08 AM.
            PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

            "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

            Comment


            • #51
              Originally posted by Kolibri View Post
              Oh, btw, just in case the answer wasn't obvious to anyone else but Vance,
              I'll begin with his own quote from the Rotorcraft Flying Handbook:




              A "portion" means a percentage. A particular gyro's prerotator proportionality (i.e., xx% of takeoff RRPM) remains more or less constant, and if takeoff RRPM is increased, then so is prerotational RRPM.



              Then, that gyro's prerotation RPM will be correspondingly higher because the same p/r horsepower available to the ring gear is now spooling up a lighter rotor disk.

              This is what I meant in my post #16 by "[a 28' rotor] will require significantly more prerotation RPM for take-off [than a 30' rotor]".




              I never limited my remark to some minimum prerotational RRPM for stability.
              Most pilots spool up much higher than that to shorten the takeoff roll, and it was in such obvious context that I wrote what I did.

              Even from my older RAF, its p/r can manage (depending on how recently serviced it is) 180-202 RRPM. I usually begin my takeoff rolls at 150-170.




              Turns out it wasn't. The modified 8H12 airfoil blades which can be made up to 4m in length are
              (according to their website) only 8" chord and perform only to a
              "maximum flight speed is 120-130 km/h"
              and thus unsuitable for a 1320lb. RAF of 200+hp. This leaves the original 8H12 airfoil blades of 3.85m max length.


              __________


              Regards, Kolibri[/COLOR]
              In my experience the prerotation rpm is unrelated to the rotor flight rpm.

              In my opinion your supposition that the prerotation rpm is some percentage of the flight rpm is flawed.

              In my opinion the required pre-rotation rpm is governed more by the blade profile and it appears to me an 8H12 is very tolerant of low pre-rotation rpm.

              Perhaps what Eddie is getting is not on the Web page.

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

              Comment


              • #52
                Your absolutely right Vance,Kolibri is clueless about what we have ordered.
                Best Regards,
                Eddie Sigman,Polvadera,nm
                (575) 835-4921

                Comment


                • #53
                  Steven thank you for you kind words and input,you are truly an awe inspiring human.
                  Best Regards,
                  Eddie Sigman,Polvadera,nm
                  (575) 835-4921

                  Comment


                  • #54
                    In my experience the prerotation rpm is unrelated to the rotor flight rpm.
                    In my opinion your supposition that the prerotation rpm is some percentage of the flight rpm is flawed.
                    Then, according to you Vance, the same/but shorter airfoil will have a higher flight RRPM (as you've already admitted),
                    but the same max prerotational RRPM?



                    ________
                    Kolibri is clueless about what we have ordered.
                    So, eddie, your Gyro-Tech rotors will not have the 8H12 airfoil?
                    They will be longer than 3.85 meters?
                    And your hub bar will be significantly improved over what I've seen on their website?

                    What's the Big Secret to what you've ordered? Why not post some photos?



                    ________
                    You are on the page where you can now buy the best composite blades in the world to your gyrocopter.
                    http://helicoptersblades.com/naca-8h...irfoil-blades/
                    http://helicoptersblades.com/naca-8h...irfoil-blades/

                    It is not unusual for a manufacture to make unsubstantiated claims about imagined features
                    and it is not unusual for a new customer to repeat those claims.

                    I wondered what the person who made the claims was thinking and what the basis for the claims were.

                    Given the challenge of using carbon fiber in rotor blades and the often poorly understood loads involved
                    in the operation of a gyroplane rotor system I feel that my inquires and statements have been reasonable.

                    I hope the testing has been more rigorous than seeing how strong the blades are in bending.

                    I feel the rotor blade is a flight critical component of a gyroplane and it is natural to wonder if the manufacturer
                    has the wherewithal to design and manufacture a quality product.

                    It would be interesting to me to know what has been done to manage the inherent challenges of carbon fiber blades.
                    That is a much bigger question than the reason for this thread.

                    Regards, Kolibri

                    PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

                    "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

                    Comment


                    • #55
                      Kolibri you are truly a wonderful and compassionate man to worry about our safety like you do,thank you.



                      Best Regards,
                      Eddie Sigman,Polvadera,nm
                      (575) 835-4921

                      Comment


                      • #56
                        eddie, my gratitude is directly proportional to your statement's sincerity.

                        Thank you, Kolibri
                        PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

                        "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

                        Comment


                        • #57
                          Originally posted by Kolibri View Post
                          Then, according to you Vance, the same/but shorter airfoil will have a higher flight RRPM (as you've already admitted),
                          but the same max prerotational RRPM?


                          Regards, Kolibri[/COLOR]
                          Yes, the pre-rotator rpm where the rotor becomes stable is unrelated to flight rpm and has more to do with the blade profile.

                          In my opinion how fast to pre-rotate has everything to do with the strength of the pre-rotator system and the need for the blades to become stable.

                          Mark Givans originally started the blades by hand on The Predator and was running 30 foot RAF blades that typically spun a little over 300 rotor rpm.

                          The Predator now has thirty foot, eight and a half inch chord Sport Copter rotor blades and my electric pre-rotator might spin them up to 100 rotor rpm. If I have a need I can let the wind take over at 80 rotor rpm.

                          I have seen the Sport Copter Blades on The Predator spin as high as 400 rotor rpm in flight.

                          Many Bensenís have an Armstrong pre-rotator that might see 60 rotor rpm and I have seen the blades well over 300 rpm in flight.

                          Puff the Cavalon was capable of seeing 220 rotor rpm during pre-rotation and the blades turned 350 to 375 rotor rpm.

                          The Predator and Puff the Cavalon took about the same distance to lift off.

                          In my opinion the flight rpm of a rotor system is governed by more than the length of the rotor blades and the weight of the gyroplane.

                          In my opinion the appropriate pre-rotation rpm has nothing to do with the flight rpm of a gyroplane rotor system.

                          When a helicopter is in autorotation one of the tasks of the pilot is to keep from over speeding the rotor system. Changing the length of the rotor blade or the weight of the aircraft is not an option during the autorotation.
                          Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                          Comment


                          • #58
                            Yes, the pre-rotator rpm where the rotor becomes stable is unrelated to flight rpm and has more to do with the blade profile.
                            Again -- and please my posts carefully -- I was never speaking about "where the rotor becomes stable" but max p/r RRPM for the shortest takeoff roll.
                            This is even more relevant in eddie's case, as his turbo can give him excessive takeoff roll AS before the RRPM has caught up. He posted about that.
                            He certainly doesn't begin his takeoff roll once the rotors have merely become stable at ~100 RRPM.



                            In my opinion the appropriate pre-rotation rpm has nothing to do with the flight rpm of a gyroplane rotor system.
                            Such was not what I claimed. I wrote that they are "related", and they are with respect to the element I'd brought up: a change in rotor diameter.

                            Also, given your many examples of p/r RRPM vs. flight RRPM, you apparently think that I believe that the first is some constant percentage of the second.
                            It's not. You seemed to misinterpret my assertion as one of causality, when I'd only described correlation.



                            In my opinion how fast to pre-rotate has everything to do with the strength of the pre-rotator system . . .
                            I partially agree, however the same p/r system will spin (assuming identical airfoils) a 28' rotor faster than a 30' rotor.
                            Less weight and lower drag are being spun by the same p/r horsepower. Of course max p/r RRPM will be higher.

                            Whether, however, the carbon-fiber airfoil of length will spool up faster remains to be tested.
                            Maybe eddie's takeoff roll will be shorter or about the same, who knows?

                            Regards, Kolibri
                            Last edited by Kolibri; 11-17-2017, 06:29 PM.
                            PP - ASEL (Piper 180, C172, RV-7A), SP - Gyro (Calidus, RAF), soloed in gliders; checkride soon

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

                            "My expectations: disclose the truth I need to fly safely, and act like you truly care about quality. Anything less is greed or laziness."

                            Comment


                            • #59
                              I expect my takeoff distance to be about the same,I prerotate to 150 rpm and then start my roll,what has made a difference is the position of my mains having,
                              moved my wheels aft enables me to get a better rotor angle which increases my rotor speed in a shorter distance,this causes my increased ground airspeed to be equalized
                              by my ability to increase the rotor speed/distance ratio to match the increase in power. which gives me a shorter takeoff roll without having a blade flap issue.
                              Best Regards,
                              Eddie Sigman,Polvadera,nm
                              (575) 835-4921

                              Comment

                              Working...
                              X