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What is the real downside of biplanes?

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  • What is the real downside of biplanes?

    You see very few biplanes in IMAC, and I’m a HUGE fan of biplanes. From a judging perspective, what are the downsides of biplanes? They can obviously do the sequences.

  • #2
    For me, its the extra work involved. Assembly takes longer, more surfaces to get trimmed, and Bipes tend to be shorter coupled making them more sensitive to my dumb fingers.



    • #3
      I flew a bipe (Aeroworks) for a couple seasons and liked it very much - easy to see. With all the extra drag, downlines were very manageable but had to manage power well to make them fly nicely. Didn't have the coupling issues mentioned as the fuse was quite long for a bipe. On the downside : 1) weight - expect a pretty big penalty there - snaps and point rolls sluggish and difficult to stop precisely. Have to anticipate reaching the point.. 2) Time to assemble. On average it would take me 30 minutes to assemble the aircraft and be ready to fly. Disassembly a little faster - about 20 minutes. 3) Have to get up and down off the ground several times during the assembly / disassembly process. As you get older this becomes a larger problem. 4) Trimming. I never did come up with a method of reliably trimming the aircraft. Sticking that wing up top makes a giant difference everywhere. I got it to fly well but there was always a nagging thought in the back of my mind that it wasn't quite right. Don't have that with a monoplane.

      I also love bipes but doubt I will ever have one again for competitive IMAC. There's a old adage to goes "Everyone wants a biplane until they have one".


      • #4
        There aren't really any issues from a judging standpoint; if anything, bipes show off wings level errors more than monoplanes. Most of the major downsides have already been mentioned. In addition what Brad and Steve brought up, I'd add that orientation can be a real challenge for some pilots as bipes can tend to turn into a "box" visually at certain points in the airspace.
        The aw 20-300 was probably the closest to being a competitive bipe for mortal pilots, but it had some serious issues. They were wildly inconsistent weight wise from one plane to another - two identically up fitted planes were known to vary by as much as five lbs in finished weight - and the wings were plagued with structural issues. The one I had was impossible to balance with anything short of a quad on the front, or multiple pounds of dead weight. I think the 20-300 is the right plane to model for precision flying, but it would be a monumental project to undertake.


        • #5
          I’m contemplating a biplane to be my backup plane (Flex Mamba 120cc). I don’t mind the extra time to setup. I had a Beast in the past, and that wasn’t too bad (4 screws and 4 pins). I never had the Beast setup with IMAC-level throws, so I’m not sure how it would have been. I just know it was an absolute blast to throw around the sky. Nothing is available right now, so I have some time to decide.


          • #6
            I had a Beast with a DA120, and it was fun to fly. Didn't track like a Carden and even with low rate throws it took a lot of work to fly smoothly thru maneuvers.

            The orientation issue that Ty mentioned was the main reason I decided to sell. Lost count of the heart spasms when flying in overcast or other sky conditions that caused it to "become a box "

            The assembly/disassembly is a pain, when storms roll thru during a contest.....or when one's back/ knees are acting getting old.


            • #7
              I competed with a Weeks Solution during my first season. Actually went very well (3rd in very first contest), but like everyone says getting it trimmed out and setup is more labor. BUT, the cool factor is there (always lots of compliments)...


              • #8
                I picked up a Flex Mamba (based on Pitts Model 12) as my backup plane. Haven’t flown it yet, so I can’t comment on flying. I can comment on how sweet it looks!

                My primary plane will be a KAM-Aero, but it will not arrive until late April. Then I still have to set it up and trim it, so most of my season will be with the Mamba.



                • #9
                  KAM-AERO is what I would like when I grow up!
                  Doug Pilcher