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What Type of Rotor Blade?

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  • What Type of Rotor Blade?

    What are the in-flight characteristics of the different blade materials? ( Extruded Aluminum, Laminated Aluminum, Fiberglass/Carbon )
    What are the safety concerns with each type?

    Thanks.
    Jerry
    435-201-9888

  • #2
    There is so much more to rotor blades than the material they are made out of I feel there would be little value in assigning characteristics to the material.
    Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

    Comment


    • #3
      Why did you choose to fly the blades that are on your gyro? Safety, performance, weight, looks, price point???
      Jerry
      435-201-9888

      Comment


      • #4
        Originally posted by Gman View Post
        Why did you choose to fly the blades that are on your gyro? Safety, performance, weight, looks, price point???
        There are not a lot of choices for a 1,400 pound gross weight gyroplane Jerry.
        I had composite RAF blades on The Predator and they were cracking on the trailing edge.
        I purchased Sport Copter blades and they have held up well and seem to perform well.
        They are fabricated aluminum.
        I feel the hub bar is a particularly nice design.
        They seem to perform well.
        Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

        Comment


        • #5
          Gman:
          This is a very loaded question.
          I have heard the following arguments
          1) Composite blades are better because there is no life limit on them
          2) Aluminum extruded blades are bad because they have life limits
          3) Aluminum bonded blades are good because they have no life limit and are stronger

          None of these three arguments really hold technical merit to me. Without getting into pissing matches, I'll throw some points that you yourself can think about

          Composites usually achieve their best strength to weight ratio with 35:65 ratio of resin content versus fiber content. That is why prepreg's are considered better because they have ideal strength to weight built-in. However, they require strict environmental controls for storage as well as process control with temperature and pressure. Composites are only good in structural applications when the process is controlled extremely well.
          The generalization that carbon fiber is stronger than fiberglass is also not completely technically true. It depends on the application. Fiberglass actually is similar in weight and strength to carbon fiber but more flexible. Carbon fiber is certainly stiffer and harder than fiberglass but not generically extremely stronger than it.
          In rotor blades one of the strengths we are looking for during each revolution is force pulling outward which directly relates to tensile strength and the ability of the material to bend (tensile modulus) without breaking. It is not necessarily true that a pure carbon fiber rotor blade is technically and structurally superior to anything. For instance, it can be shown that fiberglass rotor blade may be able to take more abuse without incurring damage or micro cracks than carbon fiber.
          https://www.linkedin.com/pulse/diffe...lass-shao-liya

          It is also misleading to state that composite structural elements as important as rotor blades have no life limit. Though it is generally accepted that composites have better fatigue resistance, they are certainly not immune. And the more you take the resin out (which provides more flexibility thus improving fatigue properties), the more you are prone to complex fatigue interactions. FAA put out a whole report on the subject in 2011
          http://www.tc.faa.gov/its/worldpac/techrpt/ar10-6.pdf

          In the gyroplane for recreational flying industry, the use of composites needs to be carefully evaluated against the amateur nature of the owner/builder and maintenance available to them. NDT methods like dye sublimation inspections to determine the condition of the substrate are not going to be common place at annual inspections to mechanics and builders. A ding on metal that causes a dent and is visible is a lot better than a ding that causes no visible damage on a composite blade but starts micro cracks that result in problems later on.

          In short there are pro's and cons to each material. Composites are usually a better material where complex curved shapes are needed and weight is a concern. In helicopters

          Comment


          • #6
            Originally posted by Gman View Post
            What are the in-flight characteristics of the different blade materials? ( Extruded Aluminum, Laminated Aluminum, Fiberglass/Carbon )
            What are the safety concerns with each type?

            Thanks.
            Gman:
            This is a very loaded question.
            I have heard the following arguments
            1) Composite blades are better because there is no life limit on them
            2) Aluminum extruded blades are bad because they have life limits
            3) Aluminum bonded blades are good because they have no life limit and are stronger

            None of these three arguments really hold technical merit to me. Without getting into pissing matches, I'll throw some points that you yourself can think about

            Composites usually achieve their best strength to weight ratio with 35:65 ratio of resin content versus fiber content. That is why prepreg's are considered better because they have ideal strength to weight built-in. However, they require strict environmental controls for storage as well as process control with temperature and pressure. Composites are only good in structural applications when the process is controlled extremely well.
            The generalization that carbon fiber is stronger than fiberglass is also not completely technically true. It depends on the application. Fiberglass actually is similar in weight and strength to carbon fiber but more flexible. Carbon fiber is certainly stiffer and harder than fiberglass but not generically extremely stronger than it.
            In rotor blades one of the strengths we are looking for during each revolution is force pulling outward which directly relates to tensile strength and the ability of the material to bend (tensile modulus) without breaking. It is not necessarily true that a pure carbon fiber rotor blade is technically and structurally superior to anything. For instance, it can be shown that fiberglass rotor blade may be able to take more abuse without incurring damage or micro cracks than carbon fiber.
            https://www.linkedin.com/pulse/diffe...lass-shao-liya

            It is also misleading to state that composite structural elements as important as rotor blades have no life limit. Though it is generally accepted that composites have better fatigue resistance, they are certainly not immune. And the more you take the resin out (which provides more flexibility thus improving fatigue properties), the more you are prone to complex fatigue interactions. FAA put out a whole report on the subject in 2011
            http://www.tc.faa.gov/its/worldpac/techrpt/ar10-6.pdf

            In the gyroplane for recreational flying industry, the use of composites needs to be carefully evaluated against the amateur nature of the owner/builder and maintenance available to them. NDT methods like dye sublimation inspections to determine the condition of the substrate are not going to be common place at annual inspections to mechanics and builders. A ding on metal that causes a dent and is visible is a lot better than a ding that causes no visible damage on a composite blade but starts micro cracks that result in problems later on.

            In short there are pro's and cons to each material. Composites are usually a better material where complex curved shapes are needed and weight is a concern. In helicopters where blades are hit by power pulses of the engine, fatigue is a much bigger concern than in auto-rotation. If you engineer the blade right for tensile strength, chord wise rigidity tensile modulus, bending loads etc. you can get away with any of these materials and construction methods and achieve good life span from the product.

            Comment


            • #7
              I wrote a good 3/4 page response with citations but the forum on submitting said "unapproved". Not sure if I am on some moderation list now or this forum is just as bad a buggy format as I think. Ah well ...

              Comment


              • #8
                It's painful to come here anymore. I think the forum has done the "one step forward" and now it's in the "two steps back" portion of the journey. Thanks for trying Abid, I appreciate it.
                Jerry
                435-201-9888

                Comment


                • #9
                  I wrote a good 3/4 page response with citations but the forum on submitting said "unapproved".
                  When writing a longer text I have made a habit of doing so in my favourite editor and then copy and past it to the input area. Or the other way round when you're done writing and before hitting "Post Reply" hit ctrl + A and ctrl + C which copies your whole text to the clipboard. If you hit a forum snag you can copy it to an empty text file afterwards. This would also save all the links and the formatting you have in the text since a sort of ASCII based tag system is used in the forum like "[QUOTE]" etc. Ever since I found out how to retrieve old posts I found the other problems in the forum not too bad and by no means killer snags.
                  Cheers,

                  Juergen

                  ..Il semble que la perfection soit atteinte..
                  ....non quand il n'y a plus rien à ajouter,...
                  ...mais quand il n'y a plus rien à retrancher...
                  - Antoine de Saint-Exupéry -

                  Comment


                  • #10
                    [QUOTE=kolibri282;n1123328]

                    When writing a longer text I have made a habit of doing so in my favourite editor and then copy and past it to the input area. Or the other way round when you're done writing and before hitting "Post Reply" hit ctrl + A and ctrl + C which copies your whole text to the clipboard. If you hit a forum snag you can copy it to an empty text file afterwards. This would also save all the links and the formatting you have in the text since a sort of ASCII based tag system is used in the forum like "
                    " etc. Ever since I found out how to retrieve old posts I found the other problems in the forum not too bad and by no means killer snags.

                    Comment


                    • #11
                      Uhmm.. Abid, it looks to me as if the purpose of your post was to highlight some technical problems of the forum software....;-)
                      Last edited by kolibri282; 08-16-2017, 02:19 AM.
                      Cheers,

                      Juergen

                      ..Il semble que la perfection soit atteinte..
                      ....non quand il n'y a plus rien à ajouter,...
                      ...mais quand il n'y a plus rien à retrancher...
                      - Antoine de Saint-Exupéry -

                      Comment


                      • #12
                        Uhm...kolibri282, after a 12 hour workday, the last thing I need is to see someone getting flamed for being honestly disappointed by a sorry excuse for a forum software implementation. The last thing I need is to have to become expert in current web technology, in order to ask/answer a few questions about gyro technologies.
                        Frank

                        Comment


                        • #13
                          Originally posted by kolibri282 View Post
                          Uhmm.. Abid, it looks to me as if the purpose of your post was to highlight some technical problems of the forum software....;-)
                          Hi
                          No. The point of my post was simply frustration. As I wrote, I compiled a fairly comprehensive answer citing sources and my opinions and it was may be 3/4 to a full page worth of composition. I did use Ctrl + C as I always do and tried to post. Said unapproved. So I logged off, logged back on, tried again. Same "Unapproved" message. Finally I gave up. This forum is used less and less because its more difficult to use. Though I have a computer science degree and you may be well versed in IT tech trends. Not everyone else is and should not have to be. The previous forum was certainly easier to use, imo.

                          Comment


                          • #14
                            You're right. Since the 'upgrade', the forum is difficult to use. Fortunately, and thanks to the URL posted by Alan_Cheatham, I can at least check the new postings...
                            Last edited by XXavier; 08-17-2017, 02:03 AM.

                            Comment


                            • #15
                              Abid,

                              Apparently the forum software flagged your post as possible spam. Maybe it was the link to LinkedIn.
                              When it does that, one of us has to approve each post. We can't do a blanket approval for each member.
                              Sorry about the trouble.
                              Mike Gaspard
                              Forum Administrator
                              Kaplan, Louisiana
                              Bensen B8MG, NX36MG

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