there’s no way back..

 Acroduster  Comments Off on there’s no way back..
Jun 182020
ribs glued to the spars

The ribs trimmed to size (sort of) Even at this stage the wing is very stiff. Normally in a balsa/built up wing, it is pretty easy to twist the structure. Due to the way the ribs are built, there is an decent amount of torsional stiffness, even at this stage. Next I have to make the root rib and tips ribs.

Next maybe the aileron, since that takes quite a bit of additional mechanical work. The TE can be added as the last bit. so that there is a nice curve along the ribs.

I’m still thinking about the tubular bracing in the wings. I don’t really need it. If I change my mind I can add it at the end. I will save quite a bit of weight, is there just ”because the original has it”. The leading edge covering will provide enough for-aft stiffness.

For my own reference: ribs are slightly under 10 grams before trimming to length. The whole wing at this stage is 335 gram, that’s including some metal. What the target weight is? No idea to be honest, I would think around 700-800 gram all ready. But up to a kilo for each wing will be ok, I need the weight!

it’s getting serious now..

 Acroduster  Comments Off on it’s getting serious now..
Jun 162020
around 40 ribs cut, and 10 glued up
looking ribly..

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.

Another day, another rib..

test fit one more time.

making ribs

 Acroduster  Comments Off on making ribs
Jun 052020
trial wing ribs.

With the wing spars ready, it’s time to start thinking about the ribs. On these wings, nothing is straightforward, every rib looks different. (which gives it those nice wings 😉

Luckily the designer was smart enough to keep all the ribs up to the aft spar the same, so the only difference is the rear section of each rib. Which means, after I sorted the profile, I decided to make some test ribs to see how it all looks.

These are really just for testing, the wood is something called lite-ply, which to be honest is pretty useless. It’s as light as balsa, but warps by just looking at it. Been carrying it around for 20 years, so time to get rid of it!

The profile is approx 13%, I might thin it down slightly, I think 12% will still fit. It’s roughly a NACA0013, so 12 will do just fine. Or 12.6, or something.. I’ll think about it. Have to make sure the servo’s fit as well!