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.
Notice my super long sanding bar, it is a real help!
The tip section is sort of ok, I can work with that.
I’ve been looking at it for too long, so let’s get going. As always, first things first. The wings are what keeps us up there, the rest is only there to keep the pilot dry and comfy.
taking the glider by the tail…
The kit I have was produced by Heinz Maassen Flugzeugbau. (I believe Heinz passed away early 2015) ….Die Maassen ASK 21 resp. später Mario Hermani (MH)-Flugmodellbau wird jetzt durch Jetisfaction produziert und vertrieben I read somewhere. However Jetisfaction is gone too. What stays are the gliders.
Wings are of a typical foam/abachi construction with ample glass and carbon under the skin (I hope).
As copied from the wing root.
However, I think the trailing edge of the wings can be improved upon. So we starts the process by figuring out the wing profile. I don’t have a 100% guarantee I am right, but it looks like I have of Helmut Quabeck profiles.
To check I enlisted the usual suspect: Profili to import the profile coordinates (found at the top of the page on Helmut’s website), do the usual fake wing construction in Profili, print the ribs on a piece of paper and see how close we are. Main profile is close. And as already determined, the trailing edge needs work. Normally I would cut a plywood template, but I don’t want to mess up the router at present, I am still producing metal chips)
The red pen mark is what I have now.
Sanding the top of the wing down to the glass skin is easy enough, the bottom part is where it gets interesting. You need to keep the hollow bit accurate. Maybe I could make a printed sanding block? I do have the coordinates after all.
works! just had to add a steel wire, because the glass eats the plastic real fast.
With the knowledge of the profile, I can also print nose templates, the nose part is round-ish, but not the way a profile should be, that much I can say.
In the meantime I am trying to learn another CAD program, one that is a bit more up to date AND can talk to my router. Getting more difficult as the years go by. (not so much the learning, but trying to make old hardware work with new software)
This part was supposed to be a quick ‘slap on some glass and it will be ready’. You know by now, if I spot a challenge, I will go for it!
nose templates.
I think that I will sleep better if I change the leading edge. Will check the other wing tomorrow and decide then.
