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Old Feb 01, 2012, 12:32 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Build Log
Thermal BLEED

Stumbled across a plank wing called Bleed the other day and thought I might try and do something with it. So I sat down and spent a few hours here and there with XFLR and my CAD, took the basic design, stretched the wings by about 200mm a side, kicking the aspect ratio up a touch to ~9.45 (if I did my math right) and I hope, dropped the wing loading down a few grams /sq.

The build plan is still a work in progress, with a few finer details left to do and I'm sure there will be a few small changes come along as the build goes through. Regardless, I'm posting what I have so far for review, so please, feel free to comment - good, bad, or ugly.

Should make it into town in the next day or two and get the plan printed out to build off of. In the mean time, I have printed out the rib templates and got some cut out today. Should get the rest of the ribs, along with the fuse parts cut tomorrow. Maybe even get the spars laminated up with CF tow as well.

The "new" things I am going to try with this build is a slide with those "super magnets" attached, with mating ones in the root of the wings for wing retention. The other is I am going to give this Skyloft covering a try and see how it works out.

Attached is a quick 3D rendering of the model, and the draft PDF of the plan. More as it comes...

Mark

EDIT - I just looked over the PDF and already see a few mistakes in the labeling of the ribs. Also, The sheeting will go over the LE spar and not butt up to it like the rib drawing shows.

EDIT - Fixed typos and sheeting layout on plan.
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Last edited by Quick61; Feb 02, 2012 at 12:23 PM. Reason: Fixed a few boo-boos in PDF / v1.2 beta posted....
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Old Feb 01, 2012, 05:20 AM
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ohmite's Avatar
Eden NY
Joined Sep 2001
540 Posts
Hey Mark,
Looks good, I will be watching to see how it comes along. Is this mainly for slope or thermal soaring? Well I guess by the name it is thermaling, but looks like some of the slope designs I've seen.
Good luck with the build .
Regards,
-Eric
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Old Feb 01, 2012, 10:30 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Eric, it was originally a slope machine and I do fly some slope, but with the extra wing area I am hoping to task this one to a dual purpose machine. If all goes according to plan, (which things hardly ever do), I'll be shooting for around 5 oz. / sq. ft. without ballast. We'll see.

Mark
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Old Feb 01, 2012, 11:06 AM
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Knoll53's Avatar
United States, CA, Marina
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I'm surprised at how far forward the CG is. Also, with such a long nose, you will surely need no trim ballast up front. Looks like a very very light plane. Should thermal well.

Kent
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Old Feb 01, 2012, 12:40 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Quote:
Originally Posted by Knoll53 View Post
I'm surprised at how far forward the CG is. Also, with such a long nose, you will surely need no trim ballast up front. Looks like a very very light plane. Should thermal well.

Kent
The CG was a toss into the ball park, from where it was on the original model and results from XFLR, then bumped a mm or two forward. Just as a starting point, which my prove out to be too much, but as the saying goes, "noes heavy flies poorly, tail heavy flies once". As said, the drawing is just a beta version and giving me something to work from. I thought the longer nose was a nice feature, and if any weight is needed to balance into trim, it should only take a little with that much leverage forward. I was just cutting out the rest of the ribs and got to thinking maybe I should slap in a set of spoilers, not so much for landing, but dethermaling.

Mark
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Old Feb 01, 2012, 11:00 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Pieces-parts starting to pile up. All ribs cut, along with fuse sides, and outside dimensions of the ply. Still have a bunch of sanding and such to do on the ribs and cutting out the holes and such in the ply but it's coming along. Sorry about the crappy pixs but the good camera just hitched a ride south and is on vacation for the next 2 months. All I have at the moment is my little key chain cam, but it's better than nothing.

Mark
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Old Feb 02, 2012, 01:39 AM
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The pics are fine. My high res photos just get beat up by the RC Groups import process.

So you're hand fabricating the parts? (as opposed to laser cutting). This is shaping up to be a quick build.

Kent
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Old Feb 02, 2012, 01:47 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Quote:
Originally Posted by Knoll53 View Post
The pics are fine. My high res photos just get beat up by the RC Groups import process.

So you're hand fabricating the parts? (as opposed to laser cutting). This is shaping up to be a quick build.

Kent
Yup, Exacto and utility knifes, sandpaper and the occasional cuss word. I know how the servers reprocess the photos. Lots of compression / derez. Just finished up the fuse doublers / slide.

Laser cutter? That's something I allow myself to dream about after indulging in a few/6 IPA's.
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Old Feb 02, 2012, 10:22 AM
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Quote:
Originally Posted by Quick61 View Post
Yup, Exacto and utility knifes, sandpaper and the occasional cuss word.
Now THAT'S what I call model building !

Kent
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Old Feb 02, 2012, 11:54 AM
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Quick1,
Keep taking the pics, I've always wanted to build a plank. I'm looking forward to seeing how you'll join the wings.
Thanks for posting the plans. Excellent work.
Swav
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Old Feb 02, 2012, 12:32 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Quote:
Originally Posted by swav View Post
Quick1,
Keep taking the pics, I've always wanted to build a plank. I'm looking forward to seeing how you'll join the wings.
Thanks for posting the plans. Excellent work.
Swav
Don't worry, I will. Crappy or not, pix will keep coming. Just fixed the boo-boos on the drawing and posted the newest PDF in post #1.

Kent, thanks, though at times, like when I'm carving on that ply, I might call it something a little different. I'm going to have to get my boy to dig out my old stepper motors and controller board (built to interface with the old DanCAD/CAM that was setup on a homebuilt router table for making sings) and haul it down with him next time he comes to visit. A small CNC router table for cutting out this ply sure would make things a lot easier on my hands.
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Old Feb 02, 2012, 11:15 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Got some more done today, After striking out finding any magnets that I wanted local, I got the plan printed and snagged up some more exacto blades and ordered some magnets on line. So with that setback, being several days until they show up and I can construct the fuse, I'll at least be able to milk out the wing construction. Laminated a few strips of CF tow onto the spars and they are now setting up, complete set of ribs all sanded down and sorted out, and I wrapped some CF/FG for the joiner tube. (we'll se how that playes out )

At any rate, the build is moving forward, inch by inch. A few more pics for the thread attached.....

Mark
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Old Feb 03, 2012, 11:32 AM
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I'm waiting for the magnets to arrive too I'm really curious about how you'll use them. I have few scratch builds under my belt, but I'm puzzling about the purpose of the part called 'slide'. I'm guessing magnets mounted in fuse and wings will provide necessary force to keep the wings attached to fuse after they are mounted on the joiner tube. Is that correct.

Keep up this great build.
Swav
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Old Feb 03, 2012, 12:03 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Quote:
Originally Posted by swav View Post
I'm waiting for the magnets to arrive too I'm really curious about how you'll use them. I have few scratch builds under my belt, but I'm puzzling about the purpose of the part called 'slide'. I'm guessing magnets mounted in fuse and wings will provide necessary force to keep the wings attached to fuse after they are mounted on the joiner tube. Is that correct.

Keep up this great build.
Swav
You basically got it. With this setup, the joiner pisn is not all that long and are straight. Wings with longer pins often use bees wax or the like to "stick" the wings on, or they use hooks and rubber bands, tape around the joint to a center section, etc. None of these looked all that good to me so I thought those "super magnets", like N45 - N50, have a lot of sticking power when in alignment with each other. Some, you just can't pull apart. You have to slide them apart. So the slide will allow the magnets to be in alignment when the wings are on, and with a pull string out the back by the fin, can be pulled to slide the magnets apart, breaking the hold the magnets have on each other and let the wing be pulled of the pin. Simple really, and no mucking about with extra hatches, tape, hooks, bands, sticky wax, etc., just slip the wings on and go.

It should be of note that I have not done this before, and this build is, on it's face, a test bed for several things for me. There is a chance that I'll be spending the most of my time during the maiden outing picking up pieces of balsa scattered across the field. But with some planning and cautious test glides, I hope to avoid that outcome.

Mark
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Old Feb 03, 2012, 01:34 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,524 Posts
Looking forward to seeing the flying results.

My only issue with using magnets for the wing retention is that the attractive force falls of very quickly with any separation. If the wings flex the rods and pry themselves apart by levering off the top contact point by enough to break the contact between the magnets then they may not have enough force to pull the wing back on against the friction of the wing rods. Once that occurs the forces on the wings COULD cause the wings to walk out on the rods. For this reason I'm more of a fan of springs or rubber bands used to retain wings. With the constant tension from a spring or multi wrapped rubber band the re-seating tension actually increases if the wing should be pried away from the fully seated position instead of falling off quickly.
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