Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Submarines => Topic started by: TomP on October 08, 2012, 10:00:51 pm
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Hi, Well this will be a slow build but I have started by marking the weld lines onto the hull from the Fritz Kohl drawings I have blown up to 1:32 scale. Started also drawing the deck which I will get made out of brass along with the flood grates along the hull. Only 1 thing where to cut the hull to gain access to the inside? Hull comes in two halves so will need joining. Cheers Tom
(http://s8.postimage.org/udkr6dz2p/photo.jpg) (http://postimage.org/image/udkr6dz2p/)
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You could split it radially, two cuts, one towards to the front, another towards the rear. This will make the boat easier to transport and store.
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Some pictures of the XXI
(http://s18.postimage.org/6k2574ijp/image.jpg) (http://postimage.org/image/6k2574ijp/)
(http://s18.postimage.org/yy7kr063p/image.jpg) (http://postimage.org/image/yy7kr063p/)
(http://s18.postimage.org/kt1rp6x2d/image.jpg) (http://postimage.org/image/kt1rp6x2d/)
(http://s18.postimage.org/j2iqnpfj9/image.jpg) (http://postimage.org/image/j2iqnpfj9/)
(http://s10.postimage.org/6su2hs6hh/image.jpg) (http://postimage.org/image/6su2hs6hh/)
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Just had the proof back from phd-design-etchings.co.uk slowly very slowly moving forward
(http://i1248.photobucket.com/albums/hh485/tommy3781/IMG_1677_zps6b41eba6.jpg)
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Hey Tom!
How old is your kit?
I thought 32nd Parallel stopped trading years ago....
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Yep, they stopped trading over 15 years ago. AFAIK the XXI was never officially a kit as such, there were a few prototype hulls punted out, and this is one of them.
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Design work back from phd-design-etchings.co.uk for the Fumo transmitter I'm very very pleased! (http://i1248.photobucket.com/albums/hh485/tommy3781/4B7CDB54-886C-4103-A837-5F72530E204B_zpsjxv07c3b.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/4B56106C-579B-4AF6-AFF1-DF6EE56F0F71_zpsjsu5vy6a.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/2051BB08-6CEA-421E-8875-2756935F0DDA_zpsvpnwqf4k.jpg)
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Wow! That is very impresive. How is the rest of the boat coming along, and the S class?
Cheers Tomp.
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Hi Phil, yeah really pleased with it, S class is also slowly moving on will be painting soon few lumps and bumps to sort first hope it wont take too long hows your destroyer going??
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Pm sent
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I have the deck now but what would be best to use to bond nickel silver to the GRP hull?
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Twin part acrylic glue. Have a word with Starloc adhesives, they'll advise you on the best product.
A good quality slow cure epoxy should also work fine, but I think the acrylic glue will be superior.
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Thanks Subculture used slow cure epoxy worked well cheers
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Good stuff. The deck shouldn't tax the adhesive much, as there is a lot of surface area and the expansion rate of GRP is fairly close to nickel silver.
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Hi Tomp. Any chance of some pics of the progres so far? I would love to see some.
Cheers Tomp.
Phil
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Hi Phil, how are you? Your wish is my command, spent a few hours on it Saturday put the deck on and joined both halves(http://i1248.photobucket.com/albums/hh485/tommy3781/338AB337-0D5A-4B22-B2E9-EA8C6F7B5D6A_zpsdhuyblx7.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/53E28FDA-7709-45A9-80A3-495A68434170_zpsahhq84og.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/12B2D63F-227D-4FA8-AD04-75B3EF1650BE_zpssu6jigrk.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/65092537-EB69-473F-8920-7E6213E1B461_zpsluiyqhmo.jpg)
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Looks very nice. I'd get some braces in that hull though, otherwise it'll move. G10 expoy glass sheet is very good for this, or you can make you own fibreglass sheet inexpensively by sandwiching saturated cloth between waxed melamine boards.
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Wow, looking very nice so far, the missus just asked me why I have turned a funny shade of green. Thanks for the pics Tomp.
Regards.
Phil :-))
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When you come to painting, I recommend you use a either a good two part epoxy primer or a decent etch primer. My preference is with the former as it's better stuff. Otherwise any paint you put on will merrily chip off your photoetched deck.
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Thank you both, yeah I'm quite pleased with it. I was going to build a Skelton inside consisting of bulkheads and braces to give it some strength. I was recommended Teroson etching primer which should be ok with acrylic paint when I get to that point a long way off from that. Once I have done the internal bits then need to build some parts for the stern
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Temporary tacked the bulkheads in to see how well they fit just need to make the cross braces and then secure it in place. Will it be ok to use Fast Glass from halfords to secure it in? The plastic is PVC I think
(http://i1248.photobucket.com/albums/hh485/tommy3781/B6D9560B-FC0E-417F-8F39-B714CBB66537_zpsoyr9o8uq.jpg)
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I've personally found that polyester resin isn't a very good glue except when bonding other polyester resin parts together, and is also best used in conjunction with glass tape reinforcement as polyester resin alone is rather brittle. I would suggest using a good acrylic adhesive (best), or more of the slow cure epoxy as this is tougher and will deal with the wide variation in expansion rates between PVC and the glass fibre hull which will stress those areas.
Rough the PVC parts up well where the bonds will be, as the adhesion will be mechanical not chemical.
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Hi TomP,
Very nice build log. I wonder if you have given much consideration to the rudder and turning circle?
I say this because I have recently put a partial rebuild of a Darnell Type XXI back on the water and my experience backs up most people's experience of the Type XXI - the rudder is not very effective.
David
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Some builders cheat a little and put in parallel mounted shafts and/or extended rudders. Another possibility if you have splayed shafts is to make a topsy turvy motor mixer which speeds up the inside motor on a turn and slows the outer one down.
I guess this is why the Russians put in a third prop on the Type XXI inspired Foxtrot class.
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Hi David, thank you yeah I have thought about it. I had an email from Mike Dory about the XXI he built he said it didn't turn very well. I'm currently building the rear planes but like Subculture said I'm going to make the prop shafts come out parallel with the hull. The other things I have planned to move the pivot point forward on the rudder and the motors will be on a mixer. I had planned for a bow thruster know this will be useless when it's moving but it might come in handy, it's just how the outlets will be hidden.
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Hi Tom,
That's good.
The Darnell XXI has splayed shafts as per the original. I have extended the rudder forwards backwards and downwards with some slight improvement in turning circle. At the moment it is in clear polycarbonate but that is not fooling anyone!
I would suggest certainly extending the rudder forward and perhaps leave it at that. (Depending on how much you value scale.)
On the plus side, she turns quite quickly when stationery using the props. So you can get out of a tight spot on the pond!
Hope this helps you at this stage of your build.
David
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Hi All,
Just an update on this and the Type XXI turning problems:
This version worked quite well but is not awfully scale and the "Yachties" in my club the Furness MBC pointed out that it was a "brake."
(http://i1079.photobucket.com/albums/w507/david_forrest1/XXIoldrudderextension_zpsf5fa2b4d.jpg)
This version met the "Yachties" approval and turns her quite well. Also easy to remove.
(http://i1079.photobucket.com/albums/w507/david_forrest1/TypeXXInewrudderextension_zps73c67367.jpg)
This photo taken at the Norwich Sub Weekend 2014 (More photos and videos on the AMS Forum.)
David
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Not great in shallow pond though. How about a triple rudder arrangement. The two out rudders would be in the prop wash, and it won't extend the draught.
Or perhaps if you had an auxiliary thruster e.g. a pump jet pushing though a slit in front of the existing rudder that only came on past say half rudder. More complex.
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I have been thinking of pivoting the rear of the boat like the picture so the rudder would then be in the prop wash just an idea may or may not work(http://i1248.photobucket.com/albums/hh485/tommy3781/xxitailidea_zps02f17718.jpg)
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Hi Tom,
I'm sure that would work too - though it is always a trade off with complexity.
Those "Yachties" (or Rag and Stick chaps!) do know a thing or two. If you have ever sailed an R/C yacht they turn on a sixpence.
It also backs up my experiences with my R class sub. You seemed to need rudder below the hull ( in non-turbulent water perhaps. ) I even found the turn sensitive to trim - stern down gave a tighter turn.
The rudder extension is designed to "knock- back" if she touches anything.
David
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Just a thought, (and perhaps pure idiocy) but competition ski boats add a skeg at the middle of the hull to decrease the turning radius...
perhaps putting a removable translucent skeg on the bottom of the boat, mirroring the sail, so they work together when the sub is submerged...
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No, not idiocy that obviously works. Also rather like the centre board of a sailing dinghy.
However the difference between surface skimmers and submarines is the very big difference in the displacement of the hull. A sub has the whole length of the hull several inches under water so probably more difficult for a skeg to function unless it is very big.
David
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You could also consider putting universal couplings between the shaft and propellers and with a mechanical linkage to the rudder with only a few degrees of side movement will improve the turning circle.
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Not given up been a little busy saving pennies for a new garage in the garden, roof going on this weekend so hope to carry on building in a few weeks. Wife has taken over my current garage for dog grooming so I'm building this for myself, insulated with heating a better lighting and space for a lathe finally
(http://i1248.photobucket.com/albums/hh485/tommy3781/IMG_3304_zpsd52c851c.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/IMG_3310_zps89317486.jpg)
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Are you building a workshop or a mausoleum? ;)
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Nice one Andy. I did begin to wonder where tomp had got too.
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insulated with heating a better lighting and space for a lathe finally
Better than room for a pony ;D
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Man cave nearly ready not long now I can get back to building.
(http://i1248.photobucket.com/albums/hh485/tommy3781/43CB3DC4-6A28-4130-BD59-817360AB01A3_zpsgoelgekd.jpg)
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Looks ideal Tomp. Have you got a kettle in there? I can't build anything with out a cuppa, not that I build much these day's. oh, and chocolate bisquits of course.
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If you are wiring it up don't forget to put the fuse box near the door. That way, when you close up for the day, everything can be switched off in one go.
I have this system but 'er indoors' always trips out afterwards to check on me. %)
ken
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Workshop nearly complete just a bit of painting but at least can start building again
(http://i1248.photobucket.com/albums/hh485/tommy3781/E1D1AFE6-3506-47A9-B76E-B5CBAFE34B56_zpszshu5ykc.jpg)
(http://i1248.photobucket.com/albums/hh485/tommy3781/C90472FB-825C-4C0F-8A99-EF9721ED6B74_zpsmclnhxoo.jpg)
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Very nice in steel. I'll bet you're looking forward to some 'time out'. I like the 'Hi Fi'. Is it for the vertically challenged ? {-)
Cheers
ken