Gliders > Slope Soaring
I'm drowning, in bits of an Mu28
Happy Days:
Yea, Don’t have a hot wire I’m afraid Bill, and certainly not one 2 mtrs long.
Fred told me that the width should be between 25 and 50mm. I brought the tape believing it was 35mm wide, but on measuring it, it turns out to be 37mm. :!:
I’m in a bit of a dilemma, don’t know whether to go ahead and sand out the groove or not. Let’s see if anyone else has an idea?
K.
johnfireball:
Hi Keith,
Why not use what you have and smooth over to profile with a lightweight spackle filler available in diy shops.
John.
gerryb:
hi keith, i have used 35mm wide spruce spars at the wing root and tapered the tips to 6mm. this taper started about 2/3 of the way out the wing. i also tapered the thickness from about 6mm at root to 3mm at the tip, also from 2/3 span.
is it possible for you to taper your carbon tape?
another 'filler' idea is to allow an extra 1mm in fred's sanding block idea. when the carbon tape is fitted and cured, glue 1.5mm balsa into the channel and then sand the balsa to the wing section shape. i have done this on spruce spars as above and it works very well.
Happy Days:
Yea, thanks for your suggestions lads. They both refer to over filling on top of the carbon tape and then re-sanding to return the wing to profile.
I guess what I am unsure about is just how critical is it to get the correct profile throughout the entire length of the wing. Remember each wing half is two meters long, and the profile changes. At the root it’s an SB96, and at the tip it’s an SB96V.
I’m thinking, okay, so I sand the groove too deep for the carbon tape. I glue the tape in place. When the glue had gone off I use filler to make up the difference, slightly over filling the remaining groove on top of the carbon tape so the filler stands proud above the original wing surface. When the filler has gone hard I start sanding. Here comes my point.
1/ The sanding block has a flat surface, the top of the wing is curved.
2/ if I just sand away the filler until I expose the foam sides of the top of the groove in the wing, then because the sanding block has a flat surface the top of the wing will now have a flat section running along the length of the top of the wing. (ie, the part of the wing above where I glued the carbon tape in.)
Because the top curvature of the wing is no longer there, (I sanded it away to make a groove to glue the tape into) I don’t know how much of a curve to sand the top of the groove to.
Have a look at the picture. (I’m not very good with “paint pot” I’m afraid.)
The picture is supposed to show the top of the wing profile.
Imagine I’ve sanded away a grove and fitted the tape and filler on top of it.
The white line shown the straight or ‘flat’ top that the sanding block would produce naturally.
Although exaggerated, the two coloured dotted lines show possible curvatures that I could shape the filler to, BUT… which curvature would be correct? (Having sanded the original curve away I no longer know what the correct curvature should be.)AND how do I sand it correctly for the entire length of the wing,…….and ensure that the other wing half is sanded to the same profile.
OR
Does it not really matter that much??? You see I have no idea how critical these profiles are.
Of course, what I don’t want to do is build the plane only to find it flys like a pig because the profile isn’t right!!!
I’m sure there is an answer to this matter, I just don’t know what it is, YET!
K.
billscottni:
If you let me know the root & tip chords Keith, I can send you full size wing sections that will help with the sanding
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