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Old Aug 11, 2003, 07:56 AM
275mph club
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
Building full-molded F5B-ships (Raketenwurm and Eisvogel)

Due to having a few days holiday, I have enough time to build two or three new full-molded competition F5B-ships called Raketenwurm and Eisvogel!
The Raketenwurm is a design from Wolf Fickenscher (Euro contest tour winner 2002 and German champion 2002), has 170,5 cm span, a MH 33 airfoil and a V-tail!
The Eisvogel is a design from Erwin Schamburger and is used by Remo Frattini and Erwin Schamburger for competition! The Eisvogel has 173 cm span, also a MH 33 airfoil and a T-tail!

Here I want to post some pictures of the different steps of the building to get a light and strong competition plane from polishing the mold up to flying the ready plane!

Last weekend I started with the painting of the fuselage and stab-molds after using the release wax for some times and polishing them! Picture shows my wing mold for the Raketenwurm!
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Old Aug 11, 2003, 08:00 AM
275mph club
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
After painting the stab-molds I did the first layup with the glass, carbon reinforcements, the tear-off tissue (nylon tissue) for the hinges and the light weight balsa! After vacuum for 24 hours I could sand the trailing edge and make the cut out for the main spar of carbon fibre!
On the picture you can see the molds for the Eisvogel-stab (I do it for a friend, who crashes his Surprise 6 and needs a new stab), the Twister-stab and the V-stab of the Raketenwurm ready for getting their main carbon-spar and the inner glass layer!
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Old Aug 11, 2003, 08:19 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
The next pictures show the molds, after getting their spar and inner layer, beeing in the vaccum bag, where they have to stay the next 24 hours!
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Old Aug 11, 2003, 08:24 AM
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Laurel, MD
Joined May 2001
12,684 Posts
nice!!! Please keep the pictures and descriptions coming...
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Old Aug 11, 2003, 08:29 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
The tear-off tissue is complete over the mold to get a fat-free surface for later bonding. The tissue and the paper over the spar and the glass absorbs the excessive resin for a light-weight sandwich!
New pictures from the fuselage-building of the Raketenwurm following tomorrow!
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Old Aug 12, 2003, 07:12 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
Here are the pictures from the building of the Raketenwurm-fuselage!
The first picture shows the two molds after painting with 2-component car paint !
The layup for the fuselage is made of thin glass for the coat and 2 layers aramid (diferent orientation) with several carbon and aramid reinforcements!
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Old Aug 12, 2003, 07:14 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
The next picture shows the molds after vacuum bagging with tear-off tissue and paper to absorb excessive resin for 24 hours. The tear-off-tissue is already removed and the edges of the molds cleaned. You can clearly see the carbon reinforcements! I use a bonding ledge (you can see in the next picture) to put the two halves together with a resin/microballons mixture coloured with epoxy paint! This makes it very easy to join the halves, getting a perfect seam-line without any bubbles and you don’t have to use a glass band or something else what is really difficult in small or curved fuselages!
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Old Aug 12, 2003, 07:15 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
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Near view of the bonding ledge!
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Old Aug 12, 2003, 07:16 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
Due to having a little time left yesterday evening, I made some carbon covers for the aileron- and flap-linkages and a carbon turbo spinner. The first picture shows the cover-molds which are designed for bigger sailplanes to cover the whole servo. I only need the small cover for the linkage because my servos are installed before the wing-molds are closed and only the rudder- horn look out of the wing!
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Old Aug 12, 2003, 07:17 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
The ready covers!
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Old Aug 12, 2003, 07:18 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
The last picture for today with the spinner-mold and the new carbon turbo-spinner!
More pictures perhaps tomorrow!
Ciao, Marcus
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Old Aug 12, 2003, 07:58 AM
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Laurel, MD
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Great!!! We must have MORE pictures... Nothing like seeing how the molded ships are built. Question... How are the MOLDS built?

Jay
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Old Aug 12, 2003, 08:43 AM
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M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
Hi Jay!
Look at my other article: Maiden flight of my new selfmade F5B-ship Eisvogel ! There is described how the molds are built!

Ciao, Marcus
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Old Aug 12, 2003, 12:07 PM
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Helsinki, Finland
Joined Jul 2002
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Great thread!
Marcus, how do you get right shape to that bonding ledge? And what weight is that kevlar in the fuselage (in g/m^2)

PS. I've been laying the carbon reinforcements to top and bottom but in (rough)landings your way to do it must absorb shocks better and keep the fuse in one piece!
Keep posting pictures, please!
/Antti
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Old Aug 13, 2003, 01:46 AM
275mph club
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
509 Posts
Hi Antti!
To get the right shape to that bonding legde you have to build a fuselage in a normal way (wet in wet; glass band) and put it back in one half of the mold! Use PVA on this mold and fuselage, screw a 6-8 mm thick plywood to the upper or lower side of the fuse with about 5-10 mm distance between the fuse and the plywood!
Fill the distance with thickened resin and you get the exact rounding of the fuse. A little bit sanding and ready is the bonding legde! On the other mold halve you have to do the same on the other side! It´s a little bit hard to describe, so i post some pictures next week when i do the layup for my Eisvogel!
When you do the layup (here aramid 63g/m² 45 degrees, 110 g/m² 90 degrees) you add all the layers and reinforcements exept the inner layer! Now you have to screw the bonding legde to the mold, looking about 0,5-1mm in the mold (a little bit more than the strengh of the later fuse-wall) add a corbon tow in the edge and add the inner layer! Ready!
I have no reinforcements at the top and the bottom because the fuse is stronger there because of the bonding legde and the added carbon tow for the edge!
Because of the good glas,aramid,carbon/resin proportion (about 60/40% weight) of the fuses using high vacuum in building the fuse don`t break so easy because they have less resin-matrix to break! They only flex and go back in their old shape! Using no vacuum you have only a glas,aramid,carbon/resin proportion of about 40/60% weight. A lot more resin that can break!
With this method you get very strong and light-weight fuses between about 95 g (Raketenwurm) and 120 g (Eisvogel, Twister) including the servo and cable!

Ciao, Marcus
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