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Old 02-26-2007, 05:06 PM   #1
Sackie
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Question about wing twist at building stage


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I am just in the process of constructing the wings of an old Great Planes Super Sportster 60 and I notice that they do not mention building in any twist to reduce stall issues. My question as this is the first low-wing aircraft I have built, is there a reason for not including this?...do low-wing aircraft not suffer to the same extent as high-wing aircraft regarding stalling and dropping a wing?...or was this possibly not considered in the original kit.

So, should I build in some?.. if so how much?... each wing just under 30" I believe and chord is roughly 10". Airfoil is symetrical with a few degrees of positive incidence.

Suggestions are fully welcome.

And before it is said, yes I know the aircraft built to kit specs used to fly quite well, but I wish to improve on a good thing and make it great if possible.
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Old 02-26-2007, 06:29 PM   #2
igor_throw_the_switch
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Sackie: The term is "washout" Some planes do well without bothering with this, and others benefit. I haven't flown an SS 60, so I really can't say if it's a problem. I'd think Great Planes would advise adding washout if it was a problem, however. Build it stock would be my advice.

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Old 02-26-2007, 07:20 PM   #3
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Thanks Brad,

Sorry, I was having a senior moment as I typed the original thread, I just coule not remember the terminology 'Wash-out' but that is correct.

I just wonder why some aircraft need it and others do not....but as mentioned previously, I have never seen 'wash-out' built into a low-wing aircraft.

I also wonder if wash-out is somewhat negated by dihedral, comments please....if so what amount of degrees would be the point of zero wash-out need.
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Old 02-26-2007, 07:46 PM   #4
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Most of the WWII combat planes have washout.

My pet theory is that it is compensation for a thin wing at slow speeds to help prevent tip stall.

A Super Sportster, being a recent design and a low speed sport plane, has a thicker wing (aspect ratio?) and performs much better at slower speeds.
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Old 02-27-2007, 06:28 AM   #5
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Planes with symetrical wings are meant to fly inverted. washout would be detrimental in this case.
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Old 02-27-2007, 08:56 AM   #6
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I had a Super Sportster 60 many years back. The only inprovement I made to the plane was to the landing gear blocks. After a few rough landings the landing gear blocks came unglued (ripped from the wing rib). I added a piece of hard balsa to the short hard wood block. This piece of hard balsa was glued to the side of the rib and extended to the leading edge. I also put one on the other side of the block (trapping it) into the trailing edge. After doing this I never had a problem with the L.G. again. In fact, I flew the plane for several years. I passed this plane on to Jabba and he flew it for many years also...I was sure happy to finally see the plane die. It was really looking old and oil soaked..
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