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Fuselage Construction Types (Read 8490 times)
Reply #14 - Feb 5th, 2018 at 9:16pm

Sky9pilot   Offline
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Kittyfritters posted this picture of truss type fuselage construction and I wanted to add them to this section.  Thanks again KF for the pictures.
Tom
 

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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Reply #13 - Jan 23rd, 2018 at 4:02pm

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THE HALF SHELL CONSTRUCTION...
They say a picture is worth a 1000 words... here's a picture of Thymekillers P-40 build on a CU (Cook Up) thread here on S&T...
As you can see this is very similar to the keel and former construction except that the formers are applied 1/2 a side at a time.  then the stringers are added and once the first side is completed, the  have shell is lifted from the board and the other side formers are added and  then the stringers to complete the fuselage.  Care must be taken to keep the fuselage from warping , giving you a banana shape!!!!
 

AlexADWhalfshell.jpg (121 KB | 2 )
AlexADWhalfshell.jpg

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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Reply #12 - Jan 23rd, 2018 at 3:41pm

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KEEL AND FORMER STRUCTURE
The keels are  usually suspended between a jig structure that allows the formers to be placed on the keels without touching the building board...here's  a picture of the Koutney P-51H showing this construction method...
The keels and formers suspended between 2 inch sq  wood blocks as a jig.  The keels are held by temporarily gluing balsa sticks 1/16 X 1/4 inch to hold the keels level through the construction process...
Pic#5 shows a more professional jig for keel construction.


Once all the formers are added to the jig upright the keels (dorsal and ventral and horizontal are added.
Then stringers are added next. Add stringer to one side and then the other/opposite side.  Once you have several stringers on each side, then remove the fuselage structure from the jig  and complete the stringers on the on each side. When complete the temporary sticks are removed by applying some acetone to the glue spot on the keels and remove the temporary stick.... Once they are removed any additional stringers can be added...here's a pic of the Bf-109F...


« Last Edit: Jan 26th, 2018 at 5:46pm by Sky9pilot »  

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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Reply #11 - Jan 23rd, 2018 at 11:04am

Sky9pilot   Offline
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THIS THREAD HAS BEEN RECONSTRUCTED DUE TO THE PHOTOBUCKET SNAFU...SORRY FOR THE PICS THAT WERE MISSING FOR A WHILE.  I'VE TRIED TO REPLACE THE PICTURES AND SOME MAY BE A BIT OUT OF ORDER! THANKS FOR YOUR UNDERSTANDING
EDIT AND REDO 23 JAN 2018.
« Last Edit: Jan 23rd, 2018 at 3:31pm by Sky9pilot »  

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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Reply #10 - Nov 28th, 2012 at 9:56am

thymekiller   Offline
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Thanks Tom. I was just curious if there was a way to do it with thinner or maybe just a tiny bit of thinner.
Thanks.

 

",,,The road goes on forever, and the party never ends..."
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Reply #9 - Nov 27th, 2012 at 11:44pm

Sky9pilot   Offline
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Don't see why the thinner couldn't be sprayed.  The dunking saturates the foam quickly allowing the wood to be moved out of the thinner quickly.  It is possible that the super glue can be affected and possibly loosen joints with continued exposure.  I haven't experienced this. 

One other note.  The super glue will attack the foam unless it is the foam safe cyano.  So application of the super glue must be done carefully.

Tom
 

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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Reply #8 - Nov 27th, 2012 at 8:19pm

thymekiller   Offline
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Pretty sure it's the same as investment casting. The mold is lost after the casting.

I have to ask, could a person just break off tiny bits of foam and pull it out that way instead of using thinner? Maybe with needle nose pliers?

Also, could a person spray the thinner on instead of dipping in a container?

Just thoughts, curious. 
 

",,,The road goes on forever, and the party never ends..."
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Reply #7 - Nov 27th, 2012 at 8:09pm

Sky9pilot   Offline
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I would assume that's true but have never done the lost wax process.

I have enjoyed this process and am planing on doing another one for an upcoming build.

Tom
 

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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Reply #6 - Nov 27th, 2012 at 1:15pm

TJH   Offline
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It's not rocket surgery...or
is it?
Central Pennsylvania

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That's a pretty cool process! It sounds like the same as an investment casting (lost wax).
 
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Reply #5 - Nov 27th, 2012 at 12:34pm

Sky9pilot   Offline
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Fernando,

The lost foam is an interesting process. 

The foam is cut and sanded to a dimension that is just less than the desired size. I use reed for the formers and balsa for the stringers and sheet areas.  So if using 1/16 balsa over the reed formers the dimension of the reed (approximately 1/16 diameter) and the stringers. 

I use cyano glue (super glues) to glue the reed former and the stringers in place.  The nose plug was just tacked on for sanding purposes.  You must leave an opening large enough to remove the foam as it dissolves in the lacquer thinner.  Some builders split the structure and remove the foam and then re-glue the outer structure back together. 

I do prefer the lacquer thinner removal because it leaves the structure intact and you need not worry about the structure warping on the re-gluing process.

Depending on the size of the fuselage a pvc pipe filled with the thinner is used to soak the foam which will immediately begin to dissolve.  You may then pull the puddy-like disolved foam through the wing saddle area or the nose block area.

Strain the thinner and place it back in the thinner container for the next fuselage.

I hope this answered your questions.  I'll be happy to answer any other questions you may have.  The super glue is not affected by this lacquer thinner.  I use a dunking motion to soak the foam and remove it as it shrinks.

Tom
 

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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Reply #4 - Nov 27th, 2012 at 11:43am

thymekiller   Offline
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Your English is fine. No problem.
Tom will be back very soon to answer your questions.
 

",,,The road goes on forever, and the party never ends..."
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Reply #3 - Nov 27th, 2012 at 11:17am

Fernando   Offline

I Love to built
Toledo ( Spain)

Posts: 6
 
I never worked Lost Foam.
It seems a very interesting technique.
No problems with the thinner?
Can be used balsa wood?

Sorry for my bad english.
 
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Reply #2 - Oct 28th, 2011 at 9:06am

thymekiller   Offline
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Excellent work Tom.  That's perfect.  Thanks. 

thymekiller
 

",,,The road goes on forever, and the party never ends..."
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Reply #1 - Oct 28th, 2011 at 5:23am

Sky9pilot   Offline
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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 11:02am by Sky9pilot »  

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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Oct 28th, 2011 at 4:19am

Sky9pilot   Offline
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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: Jan 23rd, 2018 at 3:58pm by Sky9pilot »  

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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