I’ve been sanding and plastering and sanding more and then some more and still there’s more to sand. All in an effort to make the ASK21 wing profile as accurate as I can. It’s a real effort, and very time consuming.
The root section is the worst, especially the nose of the profile was not even close. I do understand the foam cutting process very well, and know where the problems are. Especially in a long tapered wings.
Anyway, every small step is one step closer to being finished.
The tip section is sort of ok, I can work with that.
AcrodusterComments Off on it’s getting serious now..
A good day was had, is the saying. Over the last week or so I have been bending the cap-strips. It is a time consuming job. First you soak them for a few days, then clamp them in a jig, then let dry for at least 24 hours. Repeat.
Since there are always minor variations in the construction, my plan is to route the outline to final shape once I have enough ribs done. That would make them all exactly the same, which is the whole purpose of all this effort.
At some stage, after laminating the wing spars, I needed to bevel them at 4 degrees for the forward, and 6 degrees for the aft spars. Could have done it by hand, but this was quicker. (After spending 2 hours thinking about it, and trying to mount the planer. ) Only do this under adult supervision. You’ve been warned. Count fingers. Keep them.
Anyway, looks good. The main spars cut to length came at 97 grams each. That’s the great thing about wood, if it is too heavy, sand some more, until you get to your target.
There are some small errors in the laser-cut parts, but nothing that I can’t fix quickly. If I remember right, at one stage I thought that I needed a bit more material around holes, so added 0,5mm to the outer contour. Should not have done that, stuff is strong enough as it is! The rear attachment point is now a bit tight, but as I said, easily fixed.
AcrodusterComments Off on Nothing like a good plan..
After many thinking’s and deliberations, I came to the conclusion it would be better to build the bottom wings first. The mounting points are already fixed to the fuse, so their alignment is hardwired into the frame. When the bottom wings are done, I can align the top a bit easier.
I had planned on making the spars from sticks I have saved for 15 years now. They are vintage, but appear to be in good straight shape. These were once destined for a Waco project that never took off. There’s enough of them, and laminating thin strips gives a nice strong spar. Rear one is approx 26 x 7mm.
I hope that having wings will make other parts easier. (famous last words.) The wing structure is going to be per full size, the hard way. The spars are what carries everything, and fore/aft stiffness is provided by 1″ alu tubing. The stuff that would be available is actually heavier then stainless steel, so I am going to use that. Which means I also need to make brackets for those tubes. And when I am at it, do all the other bits I need as well.
Glueing strips together is not that exiting, but this is the result.
And for the rest, a bit of sanding and shaving to get to the correct size. I love the smell of pine!