Announcement

Collapse
No announcement yet.

A frame fairings.... any good?

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

  • A frame fairings.... any good?

    Hello,

    I see the ace cyclone wing comes with A frame and pylon fairings. Has anybody tired it with and without the fairings? Does it make any measurable difference to anything?

    happy new year

    colin

  • #2
    A frame fairings.... any good?

    From my days teaching this stuff - the drag associated with round tube as compared to aerofoil tube is significantly more - so must show a better fuel economy.

    Comment


    • #3
      A frame fairings.... any good?

      Here's two articles from Oz Report:

      Yet, more on aluminum aerofoil base tubes

      Relevant section:

      [i]The decrease in coefficient of drag between a round and an airfoil section is remarkable. An airfoil section can have a coefficient of drag as little as 1/20th that of a round section.
      Don't believe it? Stick a round upright out of the car at 60mph, then stick an airfoil section out. The difference in air resistance is amazing.

      For the section used in the Moyes (read now available to every one) bar it is reasonable to expect the coefficient of drag will be

      Comment


      • #4
        A frame fairings.... any good?

        Bit more info on drag of round v streamlined tube.. by Ken Kuhn EAA (1966)

        http://a.moirier.free.fr/A%E9rodynamique/Tra%EEn%E9e/Parasite%20resistance,%20struts%20and%20wires.pdf

        Comment


        • #5
          A frame fairings.... any good?

          paul,steve,wally

          thanks guys for the info (some good stuff there) , i kinda understand the theory. i can see how a perfect aero shaped strut would be much better than a round tube, but how does a mylar fairing folded around an existing tube (with what i'm guessing is a 4-5mm wide velcro closure) perform at 50mph on an already draggy structure.

          just something i was wondering about while its not flyable

          colin

          Comment


          • #6
            A frame fairings.... any good?

            It won't be worse than the round tube, and will be a lot better. Felix Ruhle at AIR did actually put Mylar fairings around the flying wires, but concluded it wasn't worthwhile.

            If you want to know the answer in terms of drag, then the easiest way is to head over to either JavaFoil or XFoil and then load the relevant stuff onto your PC or run the applet with Java enabled, then model your imperfect fairing and see what the lift and drag co-efficients turn out to be. You can compare this with a round tube or the perfect thing. Don't forget you'll need to pick a symmetrical aerofoil if you want to use a library one.

            I last used this about 4 years a ago when I was trying to get a handle on how reflex affected the lift co-efficient and Cp of a paraglider/paramotor reflex wing.

            It's a bit of a faff getting the profile loaded in but once you have, you can then tweak things like the imperfection in the trailing edge.

            Comment


            • #7
              A frame fairings.... any good?

              Chaser short uprights are not much drag compared to a fat bloke in a flapping Ozee though.. Pointing your toes on a pod less trike might make more difference...

              And it will trim slower - as A frame drag below the hangpoint applies a little bar back pressure..

              And it will be heavier - which will produce more induced drag..

              And profile drag is a square law so on a slow plane it's less effective than on a fast one.

              However I would do it ( and have done it) looks better and makes you feel like you are improving it. And it will reduce drag - even if the difference is too small to measure definitively in terms of speed or fuel consumption.

              It's easy to do with some thin plastic sheet and a sewing machine to attach the Velcro - the self adhesive stuff will fall off after a shortish while. The Air Creation upright fairings are a good model for how to do it. Ben and I first used them when we flew in the 1993 European Championships in Czech. Ben made them, and then Air Creation ( who's machine we were using) liked them and asked if they could copy..

              When I was competing in a chaser I used strong cable ties ( one at each end each side) to pull the two flying wires together one behind the other - which in theory reduces the drag of the set by over 1/2.

              Paul

              Comment


              • #8
                A frame fairings.... any good?

                Hi paul

                with a little tongue in cheek.. i'm not a big fan of doing stuff that makes me feel like its better, at the cost of complexity risk, which was why I was wondering if someone had done it and notice a real world improvement in the 50mph world.

                Simplistically, if it was so simple why did p&m not make kits for blades and quantums back in the day if anything could be measured?

                cable ties on the wires is interesting, i'll put that on my list of things to test should it ever be flyable again.

                oh, and its already been pointed out to be me that work on the 'fat bloke in the ozee' should be a higher priority that getting the sewing machine out. :-)

                cheers

                colin

                Comment


                • #9
                  A frame fairings.... any good?

                  Got some Blade Aerotrak alloy fairings on the Magic Trike undercart legs, they may reduce drag and add strength, but the real reason was to make them look chunkier.

                  Ace have been researching the Kamm tail section; this has a chopped off trailing edge, exploiting the aerodynamic false 'tail' that forms behind.

                  I did some CAD drawings for John of the section as a favour, he then put that into an extrusion company and he's going to introduce it soon, I wanted to buy some but got the Aerotrak fairings first so didn't bother.

                  It would make lovely upright fairings, or swap for the existing, with care...

                  Cheers

                  Kev

                  Attached files
                  G-KEVA
                  BMAA 5696

                  "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

                  R.J. Mitchell :- Designer of the Supermarine Spitfire

                  Comment

                  Working...
                  X