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I am sure there are a lot more 601, 701 and 750's out there that have experience this than Cruzer builders since the numbers are still low on builders at the moment. So I wanted to post this in the general area. I do also realize this is a new airfoil for Zenith so the problem may only by with the different shape of this leading edge. I assume that STOL has a much more "blunt" nose.
There is about a 6mm small flange on the leading edge with eventually rolls into an 18mm flange for top/bottom of rib. I am having a hard time getting the metal to lay over with our crinkling up into a mess. Zenith press forms these parts into a die I assume, we are hammering them over wood. When scratch building do we need to remove some extra metal so there is less to bend over? Change fluting locations or add more? (photos attached).
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.
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
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.
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.
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)
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!)
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).
Same here on my SG Storm 400. You can see that approach on wings and stabilizer/elevator
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!
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.