Cliff Charlesworth Olympia build in Bishop, CA.

[Barry_Cole]

Greg,
If you have a problem with uploading, just send them to me:-

modelgliding@aol.com

BC

[Greg Smith]

Thanks, Barry! I need to reduce the size of my images and they should post. Watch this space!

[Greg Smith]

Trying a new way for a picture...

[Greg Smith]

Fitting the canopy!

[Greg Smith]

So I've started on the wings. I'm trying to construct the main spars accurately. The lines on the plans are not perfectly straight,so I'm using steel straight edges rather than the plan. The spruce spar parts are required to be tapered, over a distance of 36 inches, by about 1/16" top and bottom. How could this be achieved accurately, or is accuracy not that important? I really can't imagine producing such a shallow slope accurately with hand tools! Added to which, the spruce itself is, naturally , not perfectly straight. Can the taper be approximate, i.e. the best I can do, without serious result? On my usual models, I would just push the spar into the existing rib slots,having attached the ribs at TE and LE, so making the spar first is new for me...

[Greg Smith]

OK, I've looked at Peter's method again: build the ribs over the lower spruce spars: much more conventional and manageable, I think?Am I right that this is not as on the plan? You fit the box sides of the spar box (balsa) after the ribs are in place, so the front of the box is in separate pieces of balsa, and the back in larger ones. This is difficult to describe! The tapering question still stands, though. How do you do it?

[Peter Balcombe]

Greg,
You are correct in thinking that my way of building the wing (ribs added onto lower spar) is different from the Cliff Charlesworth plan.
Cliff liked building up a complete spar assembly first, then added front & rear sections of each rib to the spar assembly.
(Obviously, any spanwise wing taper has to be built into the spar assembly in addition to any chord wise thickness taper).
I like keeping the ribs in one piece to preserve the wing section profiles.

I cannot remember now if my laser cut ribs from Cliff Evans had building tabs on them at the start (I am pretty sure they did not), but otherwise I would have built up the whole assembly onto the lower spar over the plan, with the lower spar sitting on thin spacers as neccesary to allow the rib notches to sit fully onto the spar, and a TE tapered balsa wedge to give the specified washout on the outboard section as shown on the plan. The lowest part of each rib sat on the building board and the TE sat on the building board or tapered wedge.
The wing thickness taper is then defined by the steadily reducing wing rib height towards the tip & the top spar follows this taper when put in place. The overall shape is then set in place by adding the spar webbing & then the D box skins in due course.

[Greg Smith]

Thank you, Peter: your explanation is perfectly clear, and I'm going to follow the same procedure. I still don't see how to make an accurate cut for the taper of the spars: I'll just have to hack and sand, I suppose. If the wing slots have to be adjusted as I go along, then so be it.I know the main thing is to get the ribs fitting the LE and TE properly, although I have occasionally used gussets when they are too short (Dept. pf embarrassing admissions). I noticed on the plans that the wing joiner box is a different length in plan and side view: 8.5" side view, 8.75" on plan view...

[Peter Balcombe]

Greg,
Just use the plan to get the correct angle for the wing joiner boxes.
I used the plan to cut a 1/8” ply core with joiner box cutout - height tapering as per plan for distance between top & bottom spars, length to allow joiner box to reach from root side of rib R4 to at least flush with outside of root rib - then face the core each side with 1/16” ply.
Epoxy the 3 ply pieces together with brass tube inside to get a solid joiner box assembly with correct dihedral angle, which can then be epoxied into the slot left above lower spar after you have carefully removed the rib sections out to (but not including R4).
It is all made a bit easier if you temporarily dry insert a length of spar material in the upper spar slots and then epoxy ply front and rear spar webbing in place out to R4 (glued only to lower spar and ribs. (Dry fitted top spar is only being used as a spacer for the webbing pieces)
Then when the temporary top spar is removed, you can remove the rib sections with a razor saw to leave a spar-width channel into which you should be able to slide the prepared joiner assembly. You will probably need to clean out the channel/sand the joiner assemblyto get it to slide in without stressing the wing assembly.
Make sure the height is ok for to allow the top spar to sit down in its slot, then epoxy the joiner assembly into place, adding the top spar at the same time.
N.B Make sure that you put the joiner assembly in with thedihedrl going the right way!!
I always have a steel joiner strip inserted during this process to (a) give something to help push the joiner assembly all the way home & (b) to check that the outer end of the joiner is ABOVE wing end rather than BELOW. This can be removed once joiner assembly is in place, prior to putting the top spar on.

I did a brief explanation of my wing joiner technique somewhere on the forum - possibly on another (1/5 scale Dart?) build thread.
Hope this helps.

[Peter Balcombe]

Greg,
Look in my Oly 2b Update build thread (Dec 2015) post where I show a couple of photos of a wing ready to have the joiner assembly added.