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Prompted by the latest magazine article & plan, I have started to build the Mike Birch Moonglow VI. The mag build shows quite significant dihedral yet the original plan and articles (available on outerzone) doesn't mention it. Can anyone advise if there was any dihedral on original models?

Thanks, Martin

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  • 2 weeks later...

I built mine from the outerzone plans early this year. It has 2" dihedral under ONE wingtip with the other panel flat on the board. The rudder response is neutral with this dihedral and that is what is needed for a competition pattern ship. Other things to do are 1) Get the COG at the rearwards point shown on the plan with either an empty fuel tank or with batteries etc. if electric. An electric conversion is tricky since the nose is relatively short for the lighter electric motors..2) If running off grass increase length of nose leg (1/2" to 1" or so) so that you have some positive wing incidence on the ground. It will then take off on its own as you build up speed. Zero incidence on the ground is OK for tarmac because you can do a smooth take off run. On grass it gets a bit bumpy and it is tricky to do a proper competition style smooth take off. 3) Keep the weight down. An electric conversion is likely to come out heavier than specified on the plan/article. They say to keep it below 6lbs but mine came out at 6lbs 5ozs RTF as an electric conversion. 4) Thrust lines. On the plan it shows zero down and zero right. I changed this to 1 degree down and 2 degrees right. Again, this is how my F3A pattern ships were set up in the past and it has resulted in clean vertical climbs and no changes to attitude under different power settings.
My Moonglow flies very similar to my F3A competition models from the late 1990s when set up this way. That shows what a good design it was in the late 1960s. The only real difference is that, with the rearward COG, it flick rolls so quickly that it is tricky to do just the one controlled flick. The axial rolls are not quite as axial, possibly due to the outboard ailerons.


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