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Old Jan 21, 2009, 10:32 AM
Mike Brinker
tr6world's Avatar
SouthEast Michigan
Joined May 2008
555 Posts
Gluing First half of Fuselage to Keel

The first piece of the body we glued was where the razorback begins. We planned to work from the center outward in case we needed to make any minor adjustments. Using Sig-Bond general purpose modeler glue. Drying time is about 15 - 30 minutes. Mark has used this glue before and says that it gives great bonding and sands very will. Most forms of CA dry very quickly, but sanding is a problem.

We used the "Gulliver" technique to hold the pieces in place while they dry. If you don't know what this is, that is OK, I just made the name up because it reminded me of "Gulliver's Travels" and the picture of the giant being tied down to the ground. My pictures below will better describe what I am talking about. We used pins and rubber bands to hold each piece of foam in place. It was actually a really good idea Mark came up with. We would wipe glue on three sides; both ends of the foam that adhere to the keel and one side of the foam that will butt up to the foam that is already positioned and rubber banded( see pictures).

Some sanding was necessary on a few of the foam pieces. The sides needed to match/mate up as perfectly as possible to provide a straight and flush bond for additional strength. I alternated from the right side to the left as I continued to glue each fuselage piece in place.

After a couple of hours, the complete left side of the fuselage is glued to the keel. After drying all night with the rubber bands in place, the fuselage will be ready to have the other side put together.
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Last edited by tr6world; Jan 21, 2009 at 04:23 PM. Reason: added a few more pictures
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Old Jan 21, 2009, 05:10 PM
ARFs make me BARF
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United States, MI, Roseville
Joined Dec 2000
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The keel is not only there for added strength but also to provide a sturdy surface to mount the stab and fin. It also provides a more solid structure to , above all things, make a straight unit. Foam, especially when cut to a wall thickness of 1/2", has a tendency to flex and my experience thus far with using a central keel has been positive.
Mark
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Last edited by mrittinger; Jan 21, 2009 at 08:08 PM.
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Old Jan 21, 2009, 05:22 PM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
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Thanks, Mark and TR6 for your reply. Mark, I have admired your published designs and may have to put some of them on my build list (which seems to be quite long already and getting longer). I wouldn't have thought that flexing would have been that much of a problem. With a fiberglas skin, it seems to become somewhat of a monococque structure, but I guess that might require a pretty heavy layer of glass. I was thinking that it might be a good method for building a Globe Swift that I have in mind. In 1/8th scale, it would be about the same size as your '47.


Tony
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Old Jan 21, 2009, 06:53 PM
Gentle 'Bella'
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Augusta, KS USA
Joined Dec 2007
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tpfing -

I've used methods very similar to the build in this thread. Odd things crop up from cutting out the parts, like they will take on a warp and not sure just why. It appears to be some kind of stress in the formation of the foam which hot wiring sometimes interacts with. Once it is glued up (that keel is a good feature!), it has pretty much been overcome. Lightweight glas or polycrylic and silkspan make a fine finish and is sturdy.
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Old Jan 21, 2009, 08:01 PM
ARFs make me BARF
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United States, MI, Roseville
Joined Dec 2000
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tpfing, The twisting or bending is a sometimes a problem while building, not after assembly. Once it is monocoque, it will remain straight for the most part. A nice feature of a keel is that you have a perfect reference line for a centerline to line up your fin, and measure from for you wing aliagnment as well. The central keel, while very simple, can actually transfer some stress throughout the fuselage on an inpact and thus reduce damage .
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Old Jan 26, 2009, 09:16 AM
ARFs make me BARF
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United States, MI, Roseville
Joined Dec 2000
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Here we have the starboard side glued in place on the keel/port side.
It was then set aside to dry over night. Mike will be now sanding the fuselage to it's nice streamlined shape, then adding the firewall and cowl ring on the nose.
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Old Jan 26, 2009, 10:46 AM
Retired and Lovin' it!
United States, KY, Sturgis
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Super!

Tony
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Old Jan 26, 2009, 10:56 AM
North East England
Joined Feb 2004
3,181 Posts
I've never built with foam before, being a confirmed 'balsa basher' but I must admit this thread is fascinating for it's construction methods. To build the same thing in balsa with bulkheads and sheet skinning would be far more complex. Look forward to seeing how you do the wings.

Steve
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Old Jan 26, 2009, 12:39 PM
ARFs make me BARF
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United States, MI, Roseville
Joined Dec 2000
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Wings will be done in inner and outer panels to allow for the ellipse.
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Old Jan 27, 2009, 08:26 PM
Imagine That!
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Tularosa, New Mexico, United States
Joined Jan 2003
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Quote:
Originally Posted by mrittinger
Ft Sill huh? Spent my basic and AIT there.....hope to not see that place again! 13B20R
Mark
Mark, are you a cannon cocker? Fort Sill is the coldest place on Earth, or at least it seemed that way when I went through FAOCS during the winter of 1969-70.

Tom
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Old Jan 27, 2009, 09:55 PM
ARFs make me BARF
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United States, MI, Roseville
Joined Dec 2000
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I was, 8" M110A2 SP guns.
Ft Sill was hotter than Hades in July , August, Sept. 86
Then I went to Frankfurt (Babenhausen, RERALLY the coldest place on earth!)), then Aberdeen Proving Ground. Then I ETS'd (Honorable Discharge) only to go IRR callback to Operation Desert Storm.....hot AGAIN! I ETS'd out with a medical the second time,(injured Medial meniscus).

Mike and I got the fuse worked on again tonight, I am sure he will post his pics soon. It is looking very nice for a hunk of insulation
Mark
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Old Jan 28, 2009, 07:57 AM
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Lawton/Fort Sill, OK
Joined Sep 2002
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I am an Air Defender (retired last year) and the Air Defense school is moving from El Paso to here. Got a job supporting said Air Defense school. It is cold (not as cold as Ft Riley KS) and we have 1/2" of ice on the roads.
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Old Jan 28, 2009, 01:20 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Sanding the Fuselage

Mark & I worked on the fuselage last night. Let me say that I was quickly humbled. The time spent to make it look nice really makes me appreciate every scratch built project found in these forums. With my project, I am taking the time and effort while trying to remain patient , but the skill only comes from experience. Mark's experience was very clear as he showed me how to work with the complex curves of the razorback portion of the plane. Getting too agressive with the sandpaper would make it difficult to fix the mistakes. As a matter of fact, sanding slowly and using very little pressure usually gives the best results. The experience that Mark shared with me was invaluable.


Techniques used:
As we took turns sanding, Mark showed me several different techniques used to get a smooth flowing line along the length of the fuselage.

Shadows - By using shadows, flaws like bows, humps and other imperfections were quickly discovered. Holding the fuselage out in front with the tail pointing towards me I stood under a light shinning directly from above. Now, as I roll the fuselage to the left (as if I were doing a barrel roll ) I carefully watched the shadow line on the side of the fuselage. A consistent line should flow across the fuselage. If there were any high spots or dips, they could be clearly seen using this technique.

Line of sight - Holding the fuselage out in front and facing the tail towards me. I compare the left to the right sides of the fuselage, I watch for waves, high spots and low spots. Any flaws noticed were addressed. We made small changes to ensure we didn't take too much off. . It was amazing to see a chunk of foam with a shape that somewhat resembled a P-47 fuselage to turn into a very smooth flowing P-47 fuselage. I am really geeked!

3. Touch & Feel - touch is very important. Sometimes our hands can do a better job of sensing imperfections in a surface than our eyes. I Smoothed my hand back and forth along the length of the fuselage searching for ripples, high spots or other imperfections. The fuselage should be smooth without gaps, dips, bumps, or lumps or waves anywhere.


Tools Used:
Mark showed me how to use several different tools including 3 different autobody hand sanding tools in a variety of shapes and lengths. One of the pictures will show a couple of the hand tools used laying on the workbench.
We also used sandpaper rolled up into a small tube, a small paint can that we wrapped sandpaper with and our hands. Each of these tools were used to level, smooth and shape the foam. We used some 80 grit sandpaper for a few of the really high spots just to cut them down, but then quickly changed over to a finer 120 grit.

Next will be the firewall & front cowl.

Mike
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Old Jan 29, 2009, 10:27 PM
I eat glue
Canada, NS, Yarmouth
Joined Jul 2006
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You guys want cold? Try Winnipeg, Manitoba Canada in January!
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