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Old Jun 19, 2012, 10:13 AM
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Curious........Has anyone built or tried to build a Bi-plane Sailplane

I was wondering if anyone has built or tried to build a Bi-Plane Sailplane? Something in say a 2M size. Hi-Start,Winchable or electric. Maybe even a Bi-plane DLG

I just thought it might be a fun project if it's at all possible.

Any thoughts,ideas,pictures,etc.or am I just one step closer to the nut house in my old age.

Eddie
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Old Jun 19, 2012, 10:36 AM
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Michigan's Upper Peninsula
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Eddie,

About four years ago a new guy showed up at our field with an electric biplane glider. He had some pretty old technology in terms of motor and battery, but he did manage to get it in the air. It really struggled. A very short flight then he had to recharge. Very sluggish on controls as well.

The plane was very heavy and the wings seemed to be over-built for a glider and the wingspan in relation to the size of the fuselage seemed short. I was impressed with the guy's perseverance since it looked like this was quite a project. If memory serves me, it kind of looked like a motorized Gentle Lady or that general layout but with two wings, one "stacked" on struts above the "regular wing". They seemed a little too close compared to a regular bipe.

My thought is that a longer, well-designed single wing would perform much better than a biplane arrangement for sailplanes. Just an opinion. Maybe an aero-engineer will pop in with some ideas.

By the way, I never saw that guy again. Think he could have made some contributions to the club considering his imagination and willingness to experiment.

Dave
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Old Jun 19, 2012, 10:39 AM
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A friend has a Stagger Wing Beech craft sloper. Fly's pretty good too. It's all ePP foam as well.
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Old Jun 19, 2012, 11:58 AM
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Granada Hills Ca.
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Hi Eddie

Was thinking about your 2 wing idea, you just might add quite a bit of weight in the wing to wing and to the fuse hook up stuff.

Plus a 2 m would be a 13 footer and that is good size, so maybe smaller would be better to keep it lighter and use 2 sticks for the rear fuse half and hook to the stab at each end.

And a small pod between the wings for the RC gear, you could use up a few sheets of paper getting this one together.

Have fun !!

G Don
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Old Jun 19, 2012, 12:19 PM
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Old Jun 19, 2012, 12:30 PM
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There was a full scale soaring bipe

Here's some info on a full scale soaring (more gliding than soaring I suspect) biplane, an early homebuilt, the Heath Super Soarer. A model of this would certainly raise eyebrows at your flying field.
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Old Jun 19, 2012, 12:39 PM
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Well, of course it is possible. But I don't see any advantage of having a second wing and it will more than double the drag. As a thermal glider it's performance would be very disappointing. But on a slope with unlimited energy available you can afford to have an aerodynamically inefficient plane and not have any problems staying up. But still there wouldn't be any other advantage than novelty value.
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Old Jun 19, 2012, 02:41 PM
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I just thought it might be a fun project. Something different.

I wouldn't expect it to be a competition type plane. But would love to see the looks on all the guys faces as you took it to the winch.
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Old Jun 19, 2012, 03:24 PM
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Buchanan Mi
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Years ago in one of the magazines (remember those things?? ) there was a picture of one that was slapped together from the remains of several gliders that died at a contest.
If it actually flew or not I don't remember.
Anybody else have something to ad???

Joe
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Old Jun 19, 2012, 09:12 PM
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I hope the link works:

http://modeliste01.skyrock.com/28082...-colab-n1.html
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Old Jun 19, 2012, 10:36 PM
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Biplanes have lower induced drag than monoplanes of the same span. Especially if the wings are fairly far apart (in the vertical direction). Of course, the wings get in each others way a bit. Perhaps the best thing for that would be to stagger them a lot, although if you don't stagger them much, you can join the tips for even less induced drag. If you swept the aft ones forward and the forward ones aft....Hmm...sounds like we just reinvented the joined wing. If the wings were not joined, it would probably help to use anhedral on the lower ones and dihedral on the upper ones. At least until it's time to land!

I think you could get a glider which had a lower sink rate than a conventional one, but it would likely have some extra drag when trying to go fast. And if you measured things in terms of L/D per building hour, it would be hopeless.
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Old Jun 21, 2012, 03:45 PM
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I remember back about 1978 I saw someone flying a biplane hobby hawk at Torrey Pines CA. It seemed to fly ok.
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Old Jun 21, 2012, 10:00 PM
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I am surprised no one reacted to the video I linked to...

Unfortunately it is a french site and you have an add that covers the video window for a few seconds before you may access it. You as well can click on the top right corner of the add to make it disappear quicker...

This project went all the way to full scale application but never passed the prototype/experimental stage as far as I know while showing some very interesting results and performances

http://modeliste01.skyrock.com/28082...-colab-n1.html
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Old Jun 22, 2012, 01:22 AM
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The wing spacing should be at least equal to the cord length of wing to keep both wings effective.

I miss my 2x4 that had great maneuverability with its short wing. Maybe with a biplane design you can create a super floater with all that wing area but that would be slightly more aerobatic than a typical 2m.
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Old Jun 22, 2012, 08:12 AM
Herk
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Quote:
Originally Posted by fnev View Post
I am surprised no one reacted to the video I linked to...

Unfortunately it is a french site and you have an add that covers the video window for a few seconds before you may access it. You as well can click on the top right corner of the add to make it disappear quicker...

This project went all the way to full scale application but never passed the prototype/experimental stage as far as I know while showing some very interesting results and performances

http://modeliste01.skyrock.com/28082...-colab-n1.html
Maybe this is the reason you didn't get a response:
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