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My winter project.

Old 10-31-2002, 05:39 AM
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Default My winter project.

Here's a plane thats been in my head for a few years. Last winter
I used a program called MetasequoiaLE to produce the plane in the images for the FMS simulator. To me this is the ultimate airplane in that it has the features I love: two wings, a Gee-Bee-ish like barrel fuselage, and a round engine (golden age looks) . I have some of it drawn out on a cad program, but I think it's time to make this virtual Bad Boy a real flyer. One undesirable trait I can see that this plane may have is nosing over easily on landings. If I can build the upper wing really light maybe it won't be so bad.
Any comments or suggestions?

Terry
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Old 10-31-2002, 05:47 AM
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Default My winter project.

Love the looks of it. Add some Bendix pylons to that pic and you'd be hard pressed to tell it from the real ones.

As for the nose over thing moving the landing gear can help but from what I've seen making a larger model seems to help as well. Less likely to trip over the clods of grass with the larger wheels.
Old 10-31-2002, 06:20 AM
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Default My winter project.

Here's another pic.
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Old 10-31-2002, 06:40 AM
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Default My winter project.

I've never seen a gee bee biplane styled like this before. I really like it :thumbup:

The only problem I can think of is that it appears to have elliptical wings. elliptical wings do have a tendency to tip stall, but with a little washout that shouldn't be a problem.
Old 10-31-2002, 02:38 PM
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Default My winter project.

Thanks for the positive remarks. I didn't realize elliptical wings tipstalled any worse than other wing planforms. I wanted them because I think they just looked the best on this plane and would also have less weight and drag because a good portion of the wing has a thinner profile. How much insidence would be a good place to start with on each wing if they had a couple degrees of washout? I was thinking of 2* positive for upper wing and 0* for lower wing if they didn't have any washout. Or should it be the other way around, 2* pos for bottom wing and 0* for the top one? or something else?
Old 10-31-2002, 03:19 PM
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Default Re: My winter project.

Originally posted by LoopyLewi
two wings, a Gee-Bee-ish like barrel fuselage, and a round engine (golden age looks) .
Neat ! I love it. But it should be named a Bi-Gee ! hehe...

Bernard
Old 11-02-2002, 08:57 PM
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Default My winter project.

Does anyone know what airfoil the real Gee-Bee R2 and Z used?
or can recommend one for me to use. All help much appreciated, thanks.

Terry.
Old 11-02-2002, 10:35 PM
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Default Great mines think alike?

I was just looking at a Tower ad with a Gee Bee ARF and thought "That should be a biplane."

The foward wing should be the one with the most incidence 2* more is good. That's what I used on these planes and they don't stall they just mush and sink like a stone.
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Old 11-02-2002, 10:41 PM
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Default elliptical wings

I haven't found elliptical wings to tip stall, the Spitfire is noted for its low speed handling also.

This plane I built doesn't tip stall, it has no washout and hardly any airfoil, it just 1/4 sheet balsa.
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Old 11-02-2002, 10:44 PM
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Default Airfoil?

Probably a Clark Y, it should be easy to check on the web.

The Clark Y has a zero lift AofA -3.51*
Old 11-02-2002, 11:45 PM
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Default My winter project.

Soarrich I think you're right about the top wing having a couple of degrees pos incidence and something like a clark Y for an airfoil , maybe thinned or even modified a bit. I have the Profili program so i would be able to do that easily. What does AofA stand for?
Old 11-03-2002, 12:58 AM
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Default My winter project.

The Gee Bee R series, the E, and the Z all used a NACA M6 airfoil that was a rediculous 8% thick. You will probably want to go a bit thicker than that. I think your design looks a bit like Steve Wolf's "Samson" biplane, except for the elliptical wings.
Old 11-03-2002, 01:11 AM
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Default My winter project.

Thanks chad. I'll see if that airfoil is in the Profili Library. Thats
a neat looking bipe in the pic. Never seen that one before.
Old 11-03-2002, 02:11 AM
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Default My winter project.

Originally posted by LoopyLewi
What does AofA stand for?
Angle of attack. Zero lift at -3.51* AofA means that if the airfoil goes throgh the air at any more postive AofA than -3.51* it makes lift.

The plane below which I built is set up with 0* downthrust, 0* main wing and 0* on the stab, flies great. With the wing set at 0* it's wing which is a Clark Y is making 3.51* of lift. The 1150 sq in wing picks up the 16 pound plane at about 20 mph.
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Old 11-03-2002, 07:05 AM
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Default My winter project.

That's a different looking plane in the pic. Did you design it? Thanks for the info. I designed a 18" long Gee-Bee monoplane powered by an old .10 os a few years back. I banded on a flat bottom wing and also made the mistake of trying to fly it without the cowl on because of engine problems. I've never seen another plane do what that thing did. The hairy flight lasted about 45 seconds. I could only get about one step behind it the whole way, then it pile drove itself into the ashpalt. I'm going to do my best to get this one right.
Old 11-03-2002, 08:16 AM
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Default My winter project.

I remember reading about a model of a racer with a large radial cowling like your design. He also tried to fly it with the cowling removed and almost crashed it as a result. When they are THIS big I gather that it needs to be on there to keep the airflow in control.

BTW, the big selling point with the M6 or any other airfoil with similar reflex in the trailing edge is that it has a minimal center of pressure travel with changes to the Angle of Attack ( that AofA I gather).

If you want to keep a smallish stabilizer area for aesthetic reasons then you need an airfoil with this minimal, zero or even positive pitching moment. You may want to look at the EH series of airfoils that are intended for swept flying wings. They tend to have pitching moments close to zero.

The other way to get a zero pitching moment airfoil is to go full symetrical. If you plan on much aerobatic flying this wouldn't be a bad choice either. But if the model comes out a little heavy then the landing speeds will be higher.

The advantage of a low pitching moment airfoil is that the stabilizer won't be overloaded at any normal flight regime and the model will handle more consistently at different speeds and attitudes. You won't get as much lift as with more negativley pitching airfoils but if you can keep the model light the lower wing loading can make up for this.
Old 11-03-2002, 03:39 PM
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Default My winter project.

Originally posted by LoopyLewi
That's a different looking plane in the pic. Did you design it?
Yep! That was last winters project.

http://www.netlabs.net/hp/soarrich/G-BRIT.html
Old 11-03-2002, 06:21 PM
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Default Love your design

I love your design, it looks similar to a project I was considering. Some time ago, I was looking for a Gee-Bee like plane to build as a profile aerobatic plane, and I was considering doing a Biplane.

The plane I found was the Laird Super Solution. Beautiful plane, elegant lines. I only abandoned the project because of the packaging problems of putting the radio in the wing. Might still be a great project on down the line.

Please keep us updated on how yours is going!
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Old 11-03-2002, 08:22 PM
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Default Laird Super Solution

That's a nice looking plane. I like that there is no top wing cabans, the wing's just sitting on the fuse, makes it MUCH easier to make. Fatten the fuse some, put your elliptical wings, you got your dream plane.
Old 11-03-2002, 08:27 PM
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Default My winter project.

I forgot to mention ypu'd be better off moving the gear to the fuse from the wings like you have it designed. The wings in the fuse let you stand the fuse up for transport, and the don't have to come forward so far.
Old 11-04-2002, 12:47 AM
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Default Re: elliptical wings

Originally posted by soarrich
I haven't found elliptical wings to tip stall, the Spitfire is noted for its low speed handling also.
That's because a spitfire doesn't have true elliptical wings . In fact, I really don't know of a real plane that does have true elliptical wings, though I'm sure there is one somewhere.

An elliptical wing will generally stall from root to tip at the same time, which won't give you much warning unlike a conventional rectangular wing that stalls at the root first. Also your ailerons probably won't be very effective, or totally ineffective during the stall. To counteract this most elliptical wings will have some washout (though real spitfires don't have any washout) and should help the tip stall problems, (if you have any)

I'm not saying to get rid of the elliptical wings, in fact I would most defiantly keep them. Elliptical wings have some nice features too, like less induced drag. I'm just trying to let you know of some of the problems you might encounter with that planform.
Old 11-04-2002, 02:00 AM
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Default Re: Re: elliptical wings

Originally posted by AKMac

An elliptical wing will generally stall from root to tip at the same time,
I don't want to get into a pissing contest, but that's not tip stall.
Old 11-04-2002, 03:03 AM
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Default My winter project.

Ok it's time to get Ollie in here
Old 11-04-2002, 03:20 AM
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Default My winter project.

Originally posted by Chad Veich
The Gee Bee R series, the E, and the Z all used a NACA M6 airfoil that was a rediculous 8% thick.
Does not M6 means that he has 6% thickness ? At least its what I believe to remember reading Dietmar Benjamin's book.

Bernard
Old 11-04-2002, 03:25 AM
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Default Re: Re: elliptical wings

Originally posted by AKMac
(though real spitfires don't have any washout)
huh ! Were did you get that from ? reall spitfires, at least the ones that I have seen up close and personal, HAVE washout !

Bernard

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