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Old Sep 23, 2006, 04:55 PM
If it ain't broke...break it!
Hangtight's Avatar
South Coast, UK
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Ring Thing

Does anyone remember those little chuck gliders you could make out of the ends of a styro cup and a drinking straw? I was looking at a couple of strips of Depron that were left on the bench, and came up with this...
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Old Sep 23, 2006, 04:59 PM
If it ain't broke...break it!
Hangtight's Avatar
South Coast, UK
Joined Jun 2006
912 Posts
Glides quite nicely. If I can find any info on the effective wing loading of this type of wing, next step is to figure out what size to make it for a small, cheap outrunner. I'm thinking of elevons and rudder tucked away in the big ring wing thing and the prop tucked out of harms way somewhere in the middle.

And a really effective colour scheme for orientation won't go amiss
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Old Sep 23, 2006, 05:19 PM
soar-ne
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Joined May 2005
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Hangtight:
A year or so ago a guy had something similar to your design. Think he used a IPS system tractor prop on a carbon fiber rod and the rear circle tilted for elevator and twisted side to side for rudder effect if I remember correctly. Cant recall what it was called to even do a search on it. Had a video of it also. Flew great as I recall. In a long camera shot it just looked like 2 circles gliding along in the air.
Keep after it!!!!!!!!
Bob
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Old Sep 23, 2006, 07:33 PM
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For something to further stimulate your idea check out this one. There is video as well.

http://www.rcgroups.com/forums/showthread.php?t=571269

Robert
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Old Sep 23, 2006, 08:06 PM
If it ain't broke...break it!
Hangtight's Avatar
South Coast, UK
Joined Jun 2006
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Thanks! Found that one a little earlier by accident when browsing another forum (VTOL I think). I like the minimal design, but this one and another similar version seem to be a little limited in their agility by only controlling the canard(?). I'm aiming for something with a little more zip!
One thing I did notice was the marked nose up attitude they both had. I wonder if it might be worth building the AoA into the structure? Mind you, my chuck glider seems to fly nice and level. Suppose there's only one way to find out
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Old Sep 23, 2006, 11:14 PM
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Forward speed and wind velocity has a lot to do with AoA. Also wong loading.

The slower your forward speed the higher the AoA. This is noticible with many flat plate designs as well. Notice the "hydro" planes too. Same thing. These planes are flying in what is more commonly known as "high Alpha" (high AoA) Very typical of low aspect ships.

The chuck glider should be pretty flat gliding. but when you increase the wing loading by adding radio gear or anything else the glider does not have will make a marked difference.

Another thing to consider is the C of G. many of those planes have a C of G that is further rearward than you might on another style plane. This allows high AoA to be more stable.

Robert
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Old Sep 24, 2006, 02:39 AM
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Another (slightly) related thread:
http://www.rcgroups.com/forums/showthread.php?t=524182
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Old Sep 24, 2006, 03:26 AM
If it ain't broke...break it!
Hangtight's Avatar
South Coast, UK
Joined Jun 2006
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Thanks minifly, I think that thread may have a reference to effective wing area of annular wings vs regular wings. Best I read it all again
http://www.rcgroups.com/forums/showthread.php?t=524182

Ahh. The sLOOP (see above link, very cool). Genius or lunacy? A good mix of both I think, and too be credited for getting my mind moving in neat little circles. Can't wait to see that fly. It should soar if powered by nothing other than the power of positive thought and encouragement

Willin, the position of the CoG was a little surprising, and eventually ended up about halfway along the total length. The high AoA shouldn't really be a problem as this is not really intended to go at high speed, more for messing around in restricted flying spots (note to wife: no that doesn't mean the living room...again. And I'm still very sorry about the lamp).

Some more research needs to be done I think. Anyone interested in an intermittant build log for something that is probably going to take me far too long and was proobably a stupid idea in the first place?
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Old Sep 24, 2006, 05:08 PM
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Hangtight, you may have been surprised where your CG fell on your plane but if you think about it, it is right where it is suposed to be.

Think this way. If you were to straighten each wing, yet leave it in it's original position on the fuse you would wind up with what is known as a tandem wing plane. ( actually yours is a Tandem. A tandem ring wing or annular wing) such a plane when you go to figure its CG would be the CG of each wing divided by the distance betweeb the 2 wings. So yes, the average lift would fall between the 2 wings, regardless of their shape.

Stupid idea? I hardly think so. Strap an egg to your forhead and jump on a rake simply to see if you can break the egg on the first try? That my friend is another thing.

The living room? Heh! It will happen again. When that lamp memory fades a bit, and more importantly when you get a design that you just KNOW will work inside... Or possibly the basement as opposed to the living room. But remember, you just know it will work!

Robert
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Old Sep 24, 2006, 05:37 PM
If it ain't broke...break it!
Hangtight's Avatar
South Coast, UK
Joined Jun 2006
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Did a little more reading today. The designer of the sLOOP suggests that the effective wing area of an annular wing is about 65% of it's total surface. My chuck glider has the front wing at 200mm dia and 70mm chord, and the rear wing at 300mm dia and 100mm chord with an overall length equal to the rear wing diameter. I think I can keep the overall weight to about 320g with a motor and battery that will provide approx 450 grams of thrust. Using a 2S LiPo should drop the weight to around 270g with 360 grams of thrust. Now all I have to do is decide on an approximate wing loading. Before I spend a while measuring flat plate wing aerobats, can anyone suggest a ballpark figure for an agile, fairly slow flyer?
I'm also tempted to retain the 120 degree spacing of the longerons, (because it looks cool) meaning I'll have elevons (but not flying surfaces) with a marked anhedral, and a rudder that may be more inclined to cause roll than yaw. I suppose it would be possible to rig a rudder that spans the full diameter of the rear wing, although this thing is going to look like a CND nuclear disarmament symbol from behind
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