Replies to This Discussion

Permalink Reply by david shrader on February 9, 2015 at 4:38am

Bryan,
Yes I would start by reducing the amount of flange on the leading edge. Try to start at the leading edge an work out both directions. If it's still fighting you trim back the flange a little above an below the leading edge. Also try widening your "V" notches in your forming blocks. Keep playing with it and you'll get it. And yea the 701 is no different as far as forming nose ribs goes. Good luck
Dave

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Permalink Reply by Michael Sipman on February 9, 2015 at 6:08am

Hi Bryan, I had this problem with some of the smaller parts i have built, have a look on Jesse Hartmans page

the use of a small square faced hammer and a round dolly with a 3mm radius takes all those wrinkles out. 

if you get the flange close to shape you can use the dolly before working the metal too much and then refit in the form if required for final finish. Works really well thanks Jesse.

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Permalink Reply by Bryan Walstrom on February 9, 2015 at 1:36pm

OK..... What about this suggestion? Cutting off the nose and installing a piece of "L" angle. Or if forming new, cutting the form block square and hammering the flange over instead? This gives some extra maneuvering room when installing the skins as well.

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Permalink Reply by Chris Aysen on February 9, 2015 at 2:14pm

No, you will not be able to contour the nose skin properly. When I was building my 701 I annealed the nose area (everything in front the first rivet) . I cleared that process with Chris Heintz himself at Sun-N-Fun several years back.

Chris / 127LA

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Permalink Reply by Bryan Walstrom on February 9, 2015 at 2:21pm

Just to add to some information I may have left out. The CruZer now has .025 leadng edge skins and the radius will have to be formed (to some degree anyway) before it is installed on the wing. Not during/after. The previous skins I believe was .016 and than  can form to nearly anything.

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Permalink Reply by Bryan Walstrom on February 11, 2015 at 8:28am

OK.  So... it is official. This is an acceptable option for scratch builders to create the ribs as per Roger. (These are his photos). This makes the rib much easier to create as well as giving a little play room when installing the wing skins later on. A quick Google search will show you that Vans RV12, Sonex, and CX4 all have a similar design in the nose ribs as well.

The top measurement is 350mm from the rear flange, and bottom is 340mm from the rear flange. (to keep things uniform). :-) Use typical "L" as a doubler on the leading edge.

Attachments:

• P1070755.JPG, 5.4 MB
• P1070751.JPG, 5.3 MB

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Permalink Reply by Bryan Walstrom on February 11, 2015 at 10:06am

I don't know exactly. I am not an engineer. Although I like to play one in my own garage! :-)

  Either way of construction is said to be acceptable. I do feel that the original idea is a little more "rigid" with certain twisting forces (twisting by hand). But in the real world functionality the rib's strength is found more in "compression" and then some "tensile"? The twisting forces of the wing are absorbed by the skins and wing attach points. (Hence the upgrade to .025 on the leading edge and .040 on bottom inboard skins). So the nose at the radius doesn't offer much/if any structural support, just leads the path for the shape. Which... does have me a little concerned for installing the skins per spec. We (the scratch builder) may need to make a wooden "Go-No-Go" gauge for the pre-bent skins to ensure conformity to the radius before bringing over to the wing skeleton. Otherwise how much or how little you pull the skins over the wings will change the leading edge... "foil" as you say.

(Am I correct in my thinking here? Again... I am NO engineer)

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Permalink Reply by Curtis Eggen on February 13, 2015 at 4:17pm

Regarding the "L" doubler and the rivets, could one instead leave enough material to add a flange to the new, flat nose and form it over just like the rest of the rib? (Apologies if this is a dumb question - I have yet to form a part!)

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Permalink Reply by Bryan Walstrom on February 13, 2015 at 4:48pm

I asked this very same question. No dumb questions here.  Roger replied that it would be best to cut it clean, add the L (which will also act as a doubler).

I am still deciding on which option I will take at the moment. I might try shortening the flange from 6mm to 3 -4mm and hammering another one out. Now that I know this area can simply be cut clean off... it takes some of the stress away of modifying to make it "work." (for the scratch builder).

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Permalink Reply by McDev on November 19, 2015 at 5:28am

Same here on my SG Storm 400. You can see that approach on wings and stabilizer/elevator

Attachments:

• IMG_0440.JPG, 2.4 MB

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Permalink Reply by Robert McNaught on February 12, 2015 at 5:32pm

Bryan

  Were that is a tighter radius than the 701 which I built. I used mbf board hardened with loctite at the radius for my form blocks. I would suggest adding a 1/8" aluminum plate radiused and mounted to your existing block and make the part nose edge between 4mm and 6mm sticking out past the block. Try using short sample pieces to practice with. other than that your parts look perfect!

                        Rob McNaught

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Permalink Reply by Bryan Walstrom on February 13, 2015 at 9:25am

Thanks. I may try it again before going with the new option of cutting the nose off. It doesn't look all that bad I guess. I was more concerened about thr roughness of the leading edge nose. But in truth... as long as the 1/8' radius is smooth and the flanged portion is lower than the skin, I guess it doesn't matter how ugly that part is. It is NOT making contact with the skin.

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