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Rudy Lee

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Joined
Apr 26, 2020
Messages
31
One reason for not gluing to ribs is that you want the fabric to be able to shift and equalize the tension across the entire surface when you begin heat shrinking it. If you glue it to the ribs, then bay tensions may differ and it will start pulling your ribs out of straight alignment. Once the fabric is taught from shrinking, then your paint application will soak into the weave and provide light adhesion to the ribs and skins.
That makes a ton of sense! Thanks for the explanation.
 

Rudy Lee

Active Member
Joined
Apr 26, 2020
Messages
31
Why not use the same material as the trailing edge?
We tried a bunch of different methods to get it to adhere along the curve of the leading edge, but it just wouldn't go on well. For the trailing edge we were just able to use a brake and bend the metal at an angle. For the leading edge we would need a giant roller to get it to shape
 

Rudy Lee

Active Member
Joined
Apr 26, 2020
Messages
31
Ok in a previous drawing there is a thin leading edge; is that gone now? If you removed that, I think you will have an airplane that does not fly well. It takes the impact of the air. I’m not saying it will not fly, but the airfoil will be changing constantly with the air hitting it. It will take a lot of skill to fly it. A leading edge is also first line of defense to hitting a bird. You don’t want all the ribs to be broken and loose shape. It will not fly enough to make an emergency landing. Glueing at the the spar is fine as long as it is a secure spot. Plenty of real covering jobs do this to hide a leading edge seam for looks, but they still glue to the leading edge.
Yes, there is no leading edge anymore. After some research, we determined that scalloping wouldn't be an issue.
 

TFF

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Apr 28, 2010
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14,529
Location
Memphis, TN
If you can change the shape with out a lot of pressure, it’s going to not be the best flyer. You will have an infinite number of airfoils on the wing at once. I’m not saying it won’t fly, but the flight character can change moment or moment. I would not like flying something like that. It might be easier to build, but I would not leave normal convention on your first design. Just for safety sake.
 

bmcj

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Apr 10, 2007
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Fresno, California
Yes, there is no leading edge anymore. After some research, we determined that scalloping wouldn't be an issue.
Not even something like a 1”x1/4” strip inserted int a leading edge slot (Kind of like balsa models do) to give the ribs more stability?
 

M Clarke

Member
Joined
Nov 8, 2020
Messages
12
Hi, just found this thread, good stuff! in regards to leading edge skins and fabric covering, I highly recommend looking at the skypup ultralight. It is almost entirely foam construction. uses a 0.8mm plywood leading edge epoxied to foam ribs. very easy to bend and gives your fabric a good surface to bond to. The construction manual shows a very simple process for covering the foam wings as well. You guys are not the first to run into these problems and the skypup plans and construction manual have a lot more useful info relating to this project. If you would like to borrow my copies, let me know and we can make it happen, Im located in socal and can mail or fly them there... I saw you tried aluminum leading edge skins with no success. I'm guessing you didn't use dead soft aluminum? dead soft aluminum should not take a lot of force to wrap around and wont want to spring back. 3m panel bonding adhesive has worked extremely well for me on sheet metal repairs. Id have to see how compatible it is with foam though.
 

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Protech Racing

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Joined
Jul 10, 2020
Messages
418
Nose ribs at 6 in will be fine . Over 100mph you may need a sheet covering .
I glued to each rib as I pulled the covering on.
 

BJC

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Joined
Oct 7, 2013
Messages
12,899
Location
97FL, Florida, USA
Would binding issues still be an issue if we're creating hinges that look like this? View attachment 108887
If so, then better not risk it and go with your suggestion with sticking to 1" aluminum. Sounds like a detachable tail is our best option then?
Not a recommendation, but an example from a new Aerolite 103:
D3BB59B3-05E2-4AAC-965B-2FBB44B4F1B0.jpeg
Two hinges per elevator, used on rudder and ailerons too. Light and simple plus easy to make and install. Note, also, the gap seal.


BJC
 

radfordc

Well-Known Member
Joined
Feb 5, 2008
Messages
1,432
Do you have any recommendations about leading-edge material?
Why not use what has been proven? A round aluminum tube for the LE and TE with compression ribs forming a strong ladder structure. Look at how almost every ultralight ever made was designed.
 
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