A moderately high AR plank flying wing - Page 2 - RC Groups
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Jan 25, 2017, 09:34 PM
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Carolynne's Avatar
Hi Kent,

Attached are some rather impromptu photos that might give you an idea of where I am up to. A few caveats though: The top sheeting is just laid in place and so will fit much better when it is finally glued after i have finished organising aileron servos and wiring. likewise the wing fillets are just cured epoxy and micro balloons and so look very rough at present.

As for your comments about the aileron/ elevator layout, I appreciate your comments. I have my own pet theories which have resulted in the layout that I sketched in the initial drawings which I am trying out here:

Bearing in mind that the Calliope was designed as a best L/D type aeroplane rather than a minimum sink type of floater. I guess with a less than 7% thick wing and as much streamlining and drag reduction as I could organise, this is pretty obvious. So, broadly, I wanted to keep the tips as clean as possible so as to not interfere too much with flow around the tip and also to limit the moment for adverse yaw. Similarly, I wanted the possibility of using splitters ( and as few as possible of them ) between the elevator and aileron so as to minimise trim drag. I also have a vaguely formed thought about using the ailerons as a 'trim' surface for the elevator. For similar reasons, I wasn't really going to consider putting spoilers in the wing.

Anyway, when it finally gets to feel the air, I will know if I'm all hot air (Gliding pun!)
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Jan 26, 2017, 10:45 AM
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Knoll53's Avatar
Now THAT is some mighty fine bench flying !
Split rudder looks good. This plane is going to look good in the air. You've done a nice job of adding interest to the often stark lines of a plank. Love the fuse.

I get your thought about limiting the moment arm for adverse yaw. So that is a good thing when you have a limited tail volume, as planks often do.

I would expect that you will land this one at fairly high speed, even with the split rudder. I hope that you can manage a video or two when comes time to land.

Jan 26, 2017, 05:07 PM
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Hussle's Avatar
I'd love to be able to see this in person Carolyn (as well as your Taborca). Whereabouts do you fly?
Jan 28, 2017, 11:19 PM
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Carolynne's Avatar
Hi Kent,

Thanks very much for your compliments! Thankfully, I like the way it is coming together too. I'm not yet sure how fast it will land as Klaus' wing using the same airfoil can, with some persuasion, slow up quite well. As for videos, I'll do my best when we get to that point!

Hussle, I'm very sorry, but I don't live in Sydney any more. In fact, I only get to Sydney quite infrequently these days. So, perhaps it might be easier for both of us if I help your curiosity by answering any questions you might have on this forum.

Carolyn
Jan 29, 2017, 03:30 PM
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Hussle's Avatar
Ah well, that's a shame. I will be sure to ask questions!

Many thanks,
Hussle
Jan 29, 2017, 07:23 PM
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Knoll53's Avatar
That IS a shame Hussle. You shoot some mighty fine video. Love the winglets blowing off in slow motion. It's better than being there. The only guy better is Martin who has a 4K camera.
Feb 03, 2017, 10:52 PM
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Carolynne's Avatar
Well, the Calliope is currently surrounded in a cloud of fine dust as I sand epoxy and micro balloons on the fuselage, and so she is not very photogenic at present. Next on the list is to arrange aileron servos, close the wings and remove and hinge control surfaces.

While that is all going on , I have been flying my Little Plank and learning stuff:

I have learnt that a small amount of negative aileron differential ( approximately 80% of the downing movement as up-going movement ) gives me a very axial roll response. While I am not yet sure why this works, I do wonder if this is a general rule. Has anybody tried this on high AR wings?

I have also learnt that you must slow the aeroplane down for landing and touchdown nose high or else it is likely to bounce back into the air with hilarious results. My Taborca has a small downward pointing fin on the rear of the fuselage that touches down first and forces the wing into a negative Aof A. The Taborca never bounces, irrespective of touchdown speed. With this in mind, the fuselage of the Calliope was designed with quite a high 'heel'. This firstly allowed me to dispose more rudder area below the vertical CG and will also help the aeroplane 'stick' when it lands.

Carolyn
Feb 04, 2017, 10:21 AM
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Knoll53's Avatar
I have a rather large ventral fin on this plane and just as you describe it makes the nose hug the ground as soon as there is contact with the ground. Regardless of speed or wing tip strike or roughness of ground. It does work quite well. My fin is rather large so it took several layer of glass and Kevlar to keep it attached to the plane. Maybe you could experiment with different sized ventral fins on your little plank to see just how small of a fin is effective at keeping the nose down.
Feb 04, 2017, 09:46 PM
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BMatthews's Avatar
LOOK AT THE GROOVE IT CUTS! ! ! ! You could plant crops in there! ! ! !
Feb 04, 2017, 10:14 PM
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Carolynne's Avatar
OK Kent,

Im sold. Calliope's heels stay!

Carolyn
Feb 04, 2017, 10:34 PM
B for Bruce
BMatthews's Avatar
Quote:
Originally Posted by Carolynne
OK Kent,

Im sold. Calliope's heels stay!

Carolyn
Keeping it is a wise idea anyway. It will aid in preventing the rudder halves dragging in the more dense grass or other items closer to the actual surface during landing if you should land with the speed brake deployed. Might just prevent a stripped gear tooth or damaged hinge.
Feb 05, 2017, 09:08 PM
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Carolynne's Avatar
A very good point Bruce.

I hate to say it, but hadn't even thought about actually landing in long grass as yet. I guess that between the high heel and retracting the split rudder just before touchdown as they do with flaps in f3/5. J/B I should ( i hope) be able to keep things more or less intact.

Carolyn
Feb 06, 2017, 01:32 PM
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Knoll53's Avatar
Although a low ventral fin will never allow for a touch and go, it does solve this problem (see 11:38). With a very forward first contact point and effectively no aft contact point, landings become a real art form. At the slopes, we used to just stuff the nose down (and hold it down) when within 1 foot of the ground.
Feb 08, 2017, 06:28 PM
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Carolynne's Avatar
Thanks Kent,

Thanks very much for the video. My Little plank doesn't get quite so wicked in its hi-jinks when I land too fast, but its definitely in that vein!

Carolyn
Feb 10, 2017, 05:42 PM
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Knoll53's Avatar

It's a catchy name...


Quote:
Originally Posted by Carolynne
So, with pencil in hand and little else to lose I started sketching the 'Calliope'.
Your Calliope project has inspired me to spin off my own swoopty doopty moderately high aspect ratio plank called the "Catastrophe".
I have yet to build a plank with top spoilers, so this should be interesting.

Have you calculated your aspect ratio yet?


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