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Wing profile shape

Matching to fuse

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Bill Reed19/06/2019 13:14:40
80 forum posts
2 photos

I am building a hi wing "trainer" style model from plans, first time .

The rib shape/profile does not match the fuse cut out very well, the gap in places is not consistent. Wing seating tape is mentioned and I do not know if the gap is allowance for this?

When cutting the ribs should I match the fuse cut out OR go with the rib shape shown?

Andy Meade19/06/2019 13:21:02
2671 forum posts
681 photos

Always stick to the rib shape yes Fuselage seat can be adjusted later with a P38 fillet and packing tape on the wing to stop it sticking.

Bill Reed19/06/2019 13:29:08
80 forum posts
2 photos

So adjust the fuse to the rib then? seems easier to do prior if the chance is there? Not altering the (angle of attack?) of course.

Robin Colbourne19/06/2019 13:38:00
443 forum posts
6 photos

If you could name the design it would help. The likelihood is that someone on the forum has built one in the past.

Sometimes if a design has the option of being three channel or four channel, the aileron wing on the four channel model might have a semi-symmetrical wing section, whilst the three channel wing will be flat bottomed.

kc19/06/2019 14:01:00
6078 forum posts
169 photos

Of course the ribs might be sheeted and maybe covered with a fibreglass bandage etc in some designs ( not just foam wings but built up in some US designs ) which would alter tthe way it matches the fuselage.

I like to make a master template with the datum line marked on to get the fuselage cutout correct. Then a pencil datum line on the fuselage to match ( maybe exactly 1 inch lower as you cannot draw on fresh air! ) Then the master template is used to make the wing rib template - usually smaller by the thickness of the wing sheeting, probably 1/16.

Bill Reed19/06/2019 15:26:34
80 forum posts
2 photos

I am no expert BUT i think its just a variation on the plan. The top leading edge is sheeted so the rib is recessed to allow that. The fuse cut out is "generally" the same as the rib BUT it touches here and a gap here, i do not know if its a case of building as is and the seating tape OR as mentioned fettle once done. Or do the "proper" builders get a good fit from the start?

I could even ask, if the rib was a exact fit in the fuse cut out, does this seating tape need to be allowed for? I think i am back to the get it right now or fettle later, sorry lads this is new pastures for me.

kc19/06/2019 15:39:19
6078 forum posts
169 photos

The important thing is that the wing seats firmly in the correct position every time to avoid changes in trim. Slight gaps don't matter althought they might let in oil from the exhaust . If the design uses dowel and wing bolts then it's nice to have it feel that its seated solidly ( but not crushed) If it uses wing bands ( everyone uses 6 and puts them on diagonally ) it is a bit free to move back under a slight crash.

Tell us what plan it is and we can probably help a bit more - there is always someone with experience of any design.

Nigel R19/06/2019 17:13:38
3156 forum posts
479 photos

I've always cut a bit oversize (1/16 ish) in the fuselage, then filled the gap with something - RTV, or wing tape.

Martin McIntosh19/06/2019 21:56:25
2970 forum posts
1090 photos

Always a problem, but usually only if wing fairings are involved. I normally coat the wing with Sellotape then apply silicone sealant to the fus, bolt the wing on and leave for a day. The important thing is to get the wing LE and TE centre lines to the plan.

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