Daniel's 2nd build

sat_be · January 7, 2024, 11:07pm

Started almost 3 years ago with my 2nd build. I started with some wings (rear and main wing) to test molding with 3d printed molds.

Rear wing:
the printed mold was glued together and coated with gelcoat, then sanded.
after treating with release agent, gelcoat was applied with a brush. Next 80g glass, when the gelcoat is sticky. Then twill and biax layers.
Each half shell was vacuum bagged (-0.6 to -0.8 bar) with peel ply. Be careful with heat (like heating blanket), pla with 15% infill will deform under pressure, if it gets above 50 degrees C.
The two cured halves need to be trimmed until they fit into the mold again.
Last step is to fill the mold with a mixture of cfk flakes and thickened epoxy with micro balloons and thickener. Trimm again. I made a 3d printed drill jig to drill the holes.

printed in esun pla+, 15% infill gyroid

glued the two halves with 2k epoxy glue

Templates from masking tape

a little bit of spray glue helps to keep the cfk edges nice

200g/m2 twill and some layers of 300g/m2 biax

reserved for link to thingiverse:

link to another backwing I designed: Hydrofoil rear wing mould by dfi - Thingiverse

backwing collection:
from top: 320cm2, 280cm2, 220cm2

Front wing:
Front wing was built the same way but with a strut from cfk covered balsa.

the mold consists of 2x4 segments that need to be glued together

spray glue to keep a sharp edge

Layers from outside to inside

trim the cured halves to fit the mold

balsa wrapped in cfk

vacuum in position with film between the shell and the strut

add some 50g/m3 foam, sanded to fit

fill with thickened epoxy mixed with micro ballons and cfk flakes

close an cure with camps

drill jig

end result

sat_be · January 7, 2024, 11:42pm

Mast:
The mast was built the same way as the wings. The mold is slightly more complicated as it consists of more than two parts. Design is from @visor360.

Glued the pieces and aligned them to be straight/90° respectively

Reinforced it with wood and glassed it over on the outside

Built an insert from forged carbon to hold the FR motor. The insert was built with a 2 part mold, filled with epoxy and cfk flakes pressed together. Pin holes to fix the motor were kept with two 5.5mm alu rods.

Finished insert

3 cfk tubes 10x8mm serve as cable channels. I put a 4th in front that could be drilled open later for passive water-cooling if necessary. The tubes just fit between the two halves. 60kg/m3 foam core sanded to fit the rest of the core.

Glued in 3mm cfk rods for better bonding

Inserts from stainless steel 1.4301. It was a pain to cut threads into this material, especially M6. I broke 2 tappers and had to drill the core a bit bigger and order some special tappers for stainless steel. Hole pattern is for RL and Flite

Put some caps to the end of the threads to get space for the screws and covered it with epoxy and cfk flakes.

Added some grease to the screws as a “release agent”

Printed a tool for alignment of the motor insert when putting the halves togetter

There are many layers of 300g/m2 biax bent around the edge at the top of the mast (@ the inside, not visible here)

3d printed tool to drill the fixing pin hole into the shell

Made the pins from titan to prevent corrosion and because I had never worked with it an wanted to try it. Quite easy to lathe, drill and even cut threads. Sanding/grinding it is really hard!

The 5.5mm pins are held in place with an M3 grub screw

Drill jig for the mast mounting holes (90x165) with bearings as drill guides. Arrows should point to the seam

HA wing from post above

RL and Flight hole pattern

Flight copy with Flyer800 wing and diys rear wing (needs an adapter to make it fit better)

sat_be · January 9, 2024, 12:35am

Board:
The board is from 30kg/m3 XPS with Airex75kg/m2 Top and bottom (flat part). It is shorter than the first one, length is 133x55x13.5cm.

The main compartment was cut with hotwire (nichrome 0.5mm)

same for the “connector” compartment

The slots for square cfk bars and the connection to the main compartment were made with an over router.

Connector plate

Square CFK tubes

connecting piece of 5mm cfk to spread load to the board and to the top

Vacuum bagged the connector box, 2 layers of cfk 200g.

connector plate with inserts was laminated into place to be flush with the main compartment,

Stainless steel inseerts to hold the mast

5mm full carbon board to fix the mast (is a bit overkill an heavy but strong)

Sandwich from 5mm CFK board an 5mm and Airex75kg/m2. Inside 1 layer of glass 280g/m3, outside 200g/m3 CFK. 3d Printed caps to cover and hold mast nut inserts in place

Glued in bottom plate and laminated the edge of the inside

Laminated front compartment for receiver and GPS. The hatch is connected through a 16mm electrical tube to the main compartment.

12mm Airex board glued on top. The4 cutouts on the side are for handle inserts.

3d printed hadle inserts, covered with 3mm CFK Board. 4mm Stainless rod to hold a Velcro loop covered with neoprene

Magnet cap with magnets to find the insert after laminating

Made a screw router addon for the Dremel flex wire extension

Routed slots for printes inserts with nuts to fix stuff later. Nuts were filled with play doh like sealing called “Coltogum”

Flatened the walls with filler.

Frame with M5 square nuts to screw the lid

Consists of 2 parts, frame an screw cover

Routed holes for the frame with a template and Dremel

Glued it in

Laminated the inside of the compartment with 2x 280g glass. Reason for glass is transparency to find the inserts!

Cut the outline with hot wire

Shaped the rails (cut and sanded)

I did not like the shape of the back, the round corners of the template were a mistake

I had to change it! glued some pieces with 1k foam

better

Windigo · January 14, 2024, 2:20pm

Wow your building everything from scratch that deserves respect!

WeightShift · February 6, 2024, 6:31pm

Amazing. Awesome detail - thanks for sharing!

sat_be · May 6, 2024, 11:18pm

Update:
I like the screw hatch design from my first build but there is a limitation in size of the commercial ones available. Therefore I built my own screw hatch. It has an M240x6mm thread with an opening of 234mm. printed in ASA-X

The epdm seal sits on the bottom side of the lid.

Magnetic phone holder

The result is a screw hatch that is flush with the deck.

sat_be · May 8, 2024, 10:40pm

Some more pictures of my progress:

Vacuum laminated the board,
3x200g cfk plus 1x100g glass on the top side. 2x200g cfk plus 100g glass on bottom side. The bag needs to be big enough to go into the cavities on the top side, otherwise the pressure from the bottom is too hard and bends the bottom plate. Applied 0.6bar vacuum.

Filler plus sanding before the last layer of cfk. I used a light 2k filler and colored it with black pigments.

Taped the edge and sanded to the tape, this is a painfull process. When the remaining cfk layer was thin enough, I cut it.

3 layers of top coat, with sanding (120 grit) in between. Then sanding with grit 120, 200, 400, 800, 1200, 1500, 2000 and polishing paste.

If I would do it again, I would not put the last layer of glass on top as this caused some visible spots where it is not transparent. It protects the cfk but without I would have got a cleaner cfk finish.