Scratch build Skipjack-conversion : Project 1710 Beluga in 1/63 scale

[JHapprich]

Hi everyone!

Back in 2012 i purchased the carbon-fibre upper and lower hull of a Skipjack SSN at about 1/72 scale that looked nice on E-Bay but would require a lot of scratch-building and so went to storage shortly after arrival.

Some time later i stepped over a website descriping in detail both original and the construction of very large BELUGA rc submarine. That Project 1710 drew my attention as the hull shape loosely resambled the Skipjack's so i had the idea to convert the mothballed kit.

Found some decent plans then and made a foam sail master and a fin master from glued sheets of papercard, covered with parcel tape. The sail was then used to make a large plaster mold for a final grp sail while i the fin was used for making rtv molds. At that time i did not know of urethane resin so i made grp fins as well.

The hull itself was stretched too much to mimic a beluga, so i had to cut out sections to achieve the proper shape and length-to-beam ratio. I ended up having several hull portions that were aligned with each other on a dead-flat construction board.

The project was then (2014) interupted in favor for some other projects ( ALFA, SIERRA, DELTA, MIKE ) and waited in a box for some years. I sometimes gave it a short look and realised i would have to make major adjustments to my original work in order to make the boat look right.

To be continued

Wait for the pictures

[JHapprich]

Sidenote: i figured the picture size i uploaded caused the post disapproval. In the past, i was informat the uploaded file did not match the allowed max. size did not happen this time...
new interface?
Bob, sorry for double posting

I will now continue here

Jörg

[JHapprich]

Back to the subject. I do not have any pictures of the poor hull portions, but i dug out the old sail master and the mold for the fins with the original papercard plug.

The white dtyrene sheet is the template for the lateral passways of the actual sail to show the difference. The old sail plaster mold was destroyed due to retrieve the grp product. Last time i used pva insulation for molding...

[JHapprich]

Finally, i took the hull parts out of storage some month ago and started to glue them back together, as i looked for another shell fir my ZERO BUBBLE ZB-1 dive cylinder.

I was better prepared with a new set of plans and knew, i got the sail all wrong, too short, too wide, too round. Furthermore, with the old longer styrene stern cone gone, i had a better idea how to produce a grp substitute.

So i first put the hull together to get started. Seams were taped and clamped in place, fixed with ca and then ground till the fabric lay bare. Cleaning with alcohol, then laminating from the inside with heavy weave. I included creating the z-cut in the process and corrected some warping that i knew from the hulls 2-piece Skipjack days.

[JHapprich]

I cut out indexing lips from the remaining hull cut-outs to align the hull halves and installed my usual locking assembly: one threaded brass block with indentions and recesses beeing laminated onto the inside of the lower bow portion, protruding over the edge with the thread for the locking bolt; and a corresponding hole outfitted with a small aluminum tube. When put together, a m4 stailess cylinder-bolt would be screwed down onto the brass block, the head sitting gapless inside the aluminum tube. The hull halves carry themselves, the bolt only prevents shifting it does not have to jold any load.

[JHapprich]

The sail needed some more work to it, i.e. it was cut longitudinally, halves ground to a different angle at the cutting edge and glued back together again to match the proper appearance.

Did not work...

I had to do something else. First, i scaled the blueprints to model scale and made some 3-side sketches. I then cut a "spine" from 1mm styrene sheet and glued it into a slot at the sail's rear. The outer shape was then filled with fibre-enhanced filler and roughly ground to shape. Voila!

The hull was then installed into the assembly jig for more measuring and further alignment.

[JHapprich]

Time to make a new stern cone! A plasticbottle with the right taper would be the template/mold. I decided to install the cone in a small tournable jig with an inner support disc instead of laminating just into the inside for some reason. First the thin wall thickness prevented a perfect circular diameter of the later grp piece, second i would achieve a perfectly smooth inner sourface that would easily match the super-smooth outer surface of the hull. However i would have to fabricate a separate tip for the cone that would later be the stern.

The primary cone was then laminated in a glass/polyester layup. I undertook quite some effort into maintaining symmetrie towsrds the center axis, this beeing necessary for grinding it to consistent wall thickness on the belt grinder in a special setup.

Beeing done, the inner bottle "core" was removed and temporaily attached to the hull to identify the correct point of overlapping, where the cone would end and translate smoothly into the main hull after filling. After doing so, the necessary length of the separate stern tip could be determined.

To produce the tip, i ground a piece of wood to proper shape. Initially, i planned to make silicon molds and pour the entire tip from Urethane with all the bushings for the propulsion shaft in it, but in the end, i again used the small jig assembly to laminate the tip directly onto the stern cone. Again, the cone was ground to shape with the beltgrinder, afterwards the stern cone was algned on the by-then shortenend main hull and fixed in place with perpendicular screws. After insulation with tape, resin was poured into the gap between the overlapping parts and glassed over after pulling the wooden plug.

[JHapprich]

On the hull for checking:



Making the wooden stern tip "plug" :

[JHapprich]

I also made a simple plane master for the control surfaces. Only a basic shape; the individual plane sets would be made from that one. Made a two-piece mold from silicone and poured 6 units from PU. 4 for the rear planes and two for making the forward diveplanes

[JHapprich]

The model was once again rigged into the jig for installation of the fins:

[JHapprich]

The present day: I drilled the holes for the forward diveplane bushings and installed the sail with CA. The small deck portions around the sail will later be made from glas/resin/filler using an outline template. I made a 3mm steel reaming rod to finalize the pivot points of the rear plane nishings for the plane axes. I will use 2mm stainless rods gor the shafts and 3mm brass tube for the bushings. The stern tube for a 4mm driveshaft will be installed, afterwards i plan to prepare the hull for grey primer and scribe on the primer surface. I also need to cut out deck "windows" and replace that portions with grp to allow the radio signal to penetrate the hull because of the carbon layup.

[He Who Shall Not Be Named]

Damned fine model building practices on display here! A massive conversion project with excellent methodologies employed at each step. Good stuff, sir.

David

[JHapprich]

Thank you, sir! Took me only ten years...

[He Who Shall Not Be Named]

Thank you, sir! Took me only ten years...

Good things take time to ferment properly.

[trout]

I have a friend that built a carbon fiber hull, thinking of stopping the surface targets from damaging his hull. It turned out signal was not getting to the receiver. He made a fiberglass top half and kept the lower half for ramming speed. If you do 2.4GHz through a scope it is a mute point.
your build will be fun to watch.