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Old Jan 05, 2013, 07:52 AM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Day 5 -- Fuselage Formers

Finally finished up the formers, and should be chopping balsa this afternoon. That Gimpscape dragon just doesn't want to die quietly. It's a DPI issue between the two programs which appears to be user-settable, and I'm just not setting them correctly.
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Old Jan 05, 2013, 07:56 AM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
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Originally Posted by kkphantom View Post
Having had a good look at the plan on outerzone, the flying surfaces on the Envoy bear an uncanny resemblance to the KK Gipsy. The upper and lower wing spars have been transposed but you could put the Gipsy's wing and tail on an Envoy and not tell the difference.
Slight difference in the sweep of the tips, but otherwise looks like it could match up. Same span and general taper...

Might make for an interesting bash -- The "Gypsy Envoy"...
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Old Jan 05, 2013, 08:12 PM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Day 5 -- First Formers Cut

I'm a little disappointed by the flimsiness of these first formers, and I may re-cut them from 3/32" sheet instead of the original 1/16" sheet before starting the glue-up of this build.

The scrap pile is smaller this time. I managed to arrange the pieces a little better.

ADDENDUM: The Mint 13 to 14 upgrade went well, and I managed to get an NVIDIA driver installed today (GT520).
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Old Jan 05, 2013, 09:29 PM
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Something I've done in the past is to dope tissue to both sides of the balsa before you mark and cut out the formers, it stops it splitting when you cut notches for the stringers and makes them much more manageable although I think that when you install the stringers, they'll stiffen up just fine. They are only there to give the rear fuselage shape so they are under no real stress. Maybe a 3/32" square strip across the bottom of each former will reinforce them and provide some extra gluing area as it looks like the grain is vertical.
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Old Jan 06, 2013, 01:44 AM
I like real wooden aeroplanes!
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The strip of 3/32" sq or 1/8" x 1/16" glued across the grain is a method I often use for formers like these, and works well, better in fact than simply cutting them from thicker sheet.
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Old Jan 06, 2013, 10:46 AM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Quote:
Originally Posted by kkphantom
Something I've done in the past is to dope tissue to both sides of the balsa before you mark and cut out the formers...
Quote:
Originally Posted by Sundancer
The strip of 3/32" sq or 1/8" x 1/16" glued across the grain is a method I often use for formers like these...
Thanks for those tips. I also noticed I had the notches sized wrong, so cutting out new ones is still needed.

The idea of "sandwiching" the balsa between doped paper reminds me of something I do with model rocket fins. I take self-adhesive label paper and attach it to both sides, creating a "composite" structure. The edges get sealed with thin CA to prevent them from de-laminating. In addition to the strength it offers, it gives me a smoother surface for paint to adhere to. Using a label, I could print the pattern out first, then apply it to the balsa, and have an accurate shape to cut by.

Adding the stiffener should resist the tendency to break and warp...

I'll post pictures of the next attempt...
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Old Jan 07, 2013, 12:22 PM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Tried a label, no improvement in the final result. I'll pick up some nitrate and tissue this week and try your method, KKP. Especially with the last two formers (F7 and F8) is the reinforcement needed. Another idea is to sand the notches instead of cutting them out with an x-acto.

Years ago I picked up a package of sanding sticks, essentially thin strips of stiff foam with sanding grit glued to one edge, that might be of the correct width. Time to dig them back out again...
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Old Jan 07, 2013, 12:43 PM
I like real wooden aeroplanes!
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Originally Posted by cpmcgraw View Post
Tried a label, no improvement in the final result. I'll pick up some nitrate and tissue this week and try your method, KKP. Especially with the last two formers (F7 and F8) is the reinforcement needed. Another idea is to sand the notches instead of cutting them out with an x-acto.

Years ago I picked up a package of sanding sticks, essentially thin strips of stiff foam with sanding grit glued to one edge, that might be of the correct width. Time to dig them back out again...
I use a trio of home made tools for cutting stringer and wing spar notches. These consist of snapped off sections of WORN junior hacksaw blades taped and CA'd together and mounted in blasa handles. 2 blades = 1/16" slots, 3 = 3/32", 4 = 1/8". Work a treat - see below.
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Old Jan 07, 2013, 02:10 PM
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Sundancer beat me to it with the hacksaw tool. I also tape a piece of wood along the blades at the depth needed for the notch.

Another useful tool is permagrits notching tools - comes in 2 sizes - 1/8 and 1/4" and simply file the notches in.

john
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Old Jan 07, 2013, 10:45 PM
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Ilkley, West Yorkshire, UK
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I use the flat file from a cheap set of needle files that I've had for years. One edge has the file...er....'teeth' on it. File down to the correct depth, then apply sideways pressure to open up slot. Keep checking with a scrap piece of stringer material......
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Old Jan 07, 2013, 10:50 PM
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Originally Posted by Colonel Blink View Post
I use the flat file from a cheap set of needle files that I've had for years. One edge has the file...er....'teeth' on it. File down to the correct depth, then apply sideways pressure to open up slot. Keep checking with a scrap piece of stringer material......
My preferred method as well, Colonel!
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Old Jan 08, 2013, 03:45 AM
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I find the neatest method ( and simplest!) is to reduce the formers by the depth of the stringers, eliminating the notches altogether (except for the first and last as these need to be full for tissue support.) The stringers are glued to the now undersize formers and produce a very neat job with no notches to line up at all.
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Old Jan 08, 2013, 05:13 AM
I like real wooden aeroplanes!
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South-west France
Joined Sep 2007
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Originally Posted by kkphantom View Post
I find the neatest method ( and simplest!) is to reduce the formers by the depth of the stringers, eliminating the notches altogether (except for the first and last as these need to be full for tissue support.) The stringers are glued to the now undersize formers and produce a very neat job with no notches to line up at all.
That is certainly the best way to avoid the dread "wavy stringer syndrome". Also means you don't have to scallop the intermediate formers away between stringers after assembly to avoid the covering sticking to them in a random and unsightly manner.
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Old Jan 08, 2013, 11:04 AM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Quote:
Originally Posted by kkphantom View Post
I find the neatest method ( and simplest!) is to reduce the formers by the depth of the stringers, eliminating the notches altogether (except for the first and last as these need to be full for tissue support.) The stringers are glued to the now undersize formers and produce a very neat job with no notches to line up at all.
Thanks, KKP! That's a good suggestion. Keeps the formers from being compromised by a wayward cut or tear. More INKSCAPE work...
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Old Jan 09, 2013, 03:00 PM
Experienced Balsa Mangler
United States, AL, Tillmans Corner
Joined Oct 2012
668 Posts
Day 9 -- Fuselage Formers, continued...

I'm still working on getting the formers cut and shaped. What I've started doing is to use 3/32" sheet and to cut them as KKP suggested. I switched to 3/32" because I had plenty of it in the scrap pile, and thus didn't have to go out and buy any.

I am making a change in material, though, for F2 through F4, switching to 1/16" plywood instead of balsa. This allows me to reinforce the wing attachment system and distribute the loads better into the fuselage. It should also help me in installing the radio mount and servo rails. Firewall F1 may need some minor changes to accommodate the motor and power system.

If all goes well, I should begin actually applying glue to some of these pieces in the next few days.
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