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Hot Topic (More than 10 Replies) Fuselage Construction Types (Read 15107 times)
thymekiller
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Re: Fuselage Construction Types
Reply #2 - Oct 28th, 2011 at 8:06am
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Excellent work Tom.  That's perfect.  Thanks. 

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Sky9pilot
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Re: Fuselage Construction Types
Reply #1 - Oct 28th, 2011 at 4:23am
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LOST FOAM AND REED CONSTRUCTION...
Lost foam and reed is a fairly new construction method...
Those of you who used to make the carved block models will understand the process of carving the foam to the shape of the fuselage.  Taking care to make sure it's 1/8 inch under the required size to allow for the reed formers that will be wrapped around the foam plug....
Pic #5
The fuselage side view and top view is cut from the plan (I prefer to use copies of the plan) and they are placed on the fuselage block.  Usually laminated from Pink or Blue insulation foam.  Most of the foam has a plastic film moisture barrior...be sure to remove this before laminating the block pieces together....don't ask me how I found this out Embarrassed Roll Eyes Sad

Once the block is ready, it pays to have a few of the blades for the breakoff blade knives from the Dollar Store or similar.  Make sure that you use a sawing motion when cutting/carving the foam block.  If you don't the foam will snag on the blade and begin to rip and chunck off and you'll have a mess... Foam really dulls blades so don't be afraid to change blades often when it starts to drag a lot...

Once the rough shape is attained finalize with 80 grit sandpaper on a block with very little pressure then 100 grit then 320 grit.  This should give you a fairly smooth surface.  

Once you have the shape then mark off all the former positions on the foam block...
Pics #1&2
You may want to mark wing root positions as well as former positions.

Now comes the addition of the reed formers. The reed was purched HERE You want the #1 reed approximately 1/16 inch diameter (1.5mm) This will be enough reed to make probably more models than you'll get to in this lifetime.  I cut the reed in length so that I'll have approximately 1 inch over lap.  I soak this in the same solution of water/amonia 50/50 over night.  This is where it gets tricky...If you're going to have balsa glued flat to a former the reed needs to be butt joined and reinforced with a short piece of reed behind the joint so you'll have a flat former to glue to.  Otherwise you can just wrap the reed and over lap the joint and glue it there.  I use Cyanoacrylate glue with kicker to glue the reed.  Cyano will attack the foam so application of the cya needs care.  I use a very small tube attached to the cya bottle that allows small amounts of glue to be applied. I then use a piece of balsa scrap dipped into some kicker and applied to the joint to harden the Cya immediately.  This keeps the Cya from running and makes a nice hard joint of the reed.  Once the reeds are wrapped around the fuselage plug and all the stringers and wingroot saddles are added the foam can be removed by soaking in laquer thinner.  The black plastic plumbing pipe 3 or 4 inches diameter works well if the fuselage will fit inside it for dunking.  Make sure there is a large opening in the structure to remove the foam through.  Nose blocks can be temporarily tacked on for shaping and then removed for the dissolving of the foam.
Pics #3&4
Feel free to ask any questions and I'll try to give you an answer or send you to additional help...
Tom
« Last Edit: Jan 23rd, 2018 at 10:02am by Sky9pilot »  

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Sky9pilot
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Fuselage Construction Types
Oct 28th, 2011 at 3:19am
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Hello...I was asked to put together a thread on fuselage construction and the different ways they can be constructed...

First lets all take a look at the BOX STRUCTURE...
Pic #1 box style fuselage
The above photo shows the begining of box construction highlighted on the plans in Bold Black lines.  The box will be constructed in 1/16 sq balsa stick (or whatever is called for on the plan) with the top and bottom of the box done and the uprights connecting the top and bottom  1/16 sq sticks.  
Pic #2 box sides built on top of each other
Once one side is completed the second side is constructed on top of the first side.  Some place wax paper or plastic wrap between the sides other just use a single edge razor to slice the sides apart.  This can be done easily if alphatic or duco cement is used.  I don't recomment not using some paper or plastic if using cyano glue.  Some purist will not like using cyano glue Embarrassed Sad Wink (cyano glue/super glue is very fast curing but is heavier than alphatic or duco type glues)

Once the sides are completed they are then joined over the top view of the plan and while held vertical by blocks of wood or metal with a ninety degree vertical edge the cross members are glued between the sides.  Usually the same sq balsa sticks are used for the cross members.  Taking your time to keep the sides vertical unless otherwise called for on the plan...
A very simple box structure is seen here in the Island Flyer which doesn't use any formers on top of or on the bottom of the fuselage box...
Pic # Island Flyer box fuselage
The box construction most of the time uses partial formers on top and on the bottom of the box structure...
the Ryan ST is an example of partial formers...
Pics #3 & 4

Once the formers/partial formers are added to the fuselage box structure then sq balsa stringers are added to the formers usually starting with the center dorsal (top) stringer(sq balsa stick). Once the dorsal stringer is in place then the ventral(bottom) stringer is placed.  Then the remaining stringers are added placing them opposite each other to to keep a balance in the tension of the balsa stringers.
Make every effort to keep the fuselage straight in this process.
Here's a pic of the Ryan with all the stringers in place on the box and former structure...
Pic @6


« Last Edit: May 22nd, 2019 at 2:01am by Sky9pilot »  

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If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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