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[salmon]

That is one gorgeous sub. I like the way your flood holes came out.

[tomp]

Thank you the kind comment OTW Designs do make a fantastic looking sub.

Spent a few hours on it today, I decided to remove the weld lines as I will try put these on when airbrushing the sub. I have also started putting on the flood holes I had made they look great really really pleased with them.

[salmon]

Ah, I see said the blind man......Those look EVEN better!
HAve you figured out a paint scheme for her?

[tomp]

Hi Salmon, Yeah I have been basing this on HMS Stonehenge as best as I can.  As you can see in this picture that's what I'm going to aim to do dark grey deck, light grey sides and dark grey hull.



Got a question I need help with, Started drawing the WTC and checking it will fit in the sub, I was thinking of using stainless steel rods externally like the Sheerline module but I can't fit it into the sub the larger end cap discs will hit the casing. So they will have to go internal but how do I seal these? also how do I seal this disc to the tube tried a few places asking about an O ring or flat seal, they were not interested in helping. Anyone know of somewhere that might be more helpful?

I have got a choice of either 100mm diameter tube or 120mm, I think I'm going to struggle fitting both motors side by side in the 100mm but will try. 

Going to put the batteries inside the WTC as there will be not a lot of room under the WTC if I have to keep it as low as possible in the sub

Again thank you for any help Tom

[Subculture]

Gnerally o-rings are used for sealing endcaps. Sheerline use a custom flat seal, not sure if there is any advantage in those, I've always found o-rings work fine, and they're easy to get hold of. There are two ways of sealing and endcap with an o-ring, radial compression and axial compression.

Radial compression seals on the inside of the tube, the advantage is that the the seal is compressed without any requirment for rods to pinch up the caps. The disadvantage can be the tubing itself- often far from perfectly round on the inside, so you can get leaks if you're not careful. This is especially the case with larger diameter tubing. Examples of commercial WTC's with axial compression are Caswell Sub Drivers and Ron Perrot's piston tank WTC's

Axial compression seals up against the end of the tube. This is usually machined for a nice flat edge. This is how Sheerline and OTW seal their modules, OTW use o-rings, Sheerline do their own thing with seals as mentioned eariler.

You need rods to compress the seals, three is plenty although some use four. To seal the ends of if running internally, you can use o-rings again or flat rubber washers e.g. tap washers. Not that you will need capped nuts to avoid water working it 's way past the seals via capilliary reaction. OTW use very nice custom machined knurled nuts. A cheaper and no less effective alternative is to use brass domed nuts (try screwfix) with washers soldered on the end, which hep spread the load, and give a nice flat surface for the seal to compress against.

For o-rings you can try the following suppliers. Most use either Nitrile or silicone The latter are softer, but a little more fragile.

http://www.simplybearings.co.uk

http://www.polymax.co.uk

I would recommend  the following sizes of o-ring seal (o-rings are always specified by internal diameter)-

100mm diameter tubing radial compression- 90mm diameter 3mm thick
100mm diameter tubing axial compression-  95-96mm diameter 3mm thick

120mm diameter tubing radial compression- 108mm diameter 3mm thick
120mm diameter tubing axial compression-  114mm diameter 3mm thick

Note that if you choose radial compression, you will need to machine a groove into the endcap. This groove should be toleranced to allow the o-ring to extrude as it is squeezed, as the rubber will not compress. The amount of squeeze can be from 15-30% of o-ring thickness, I recommend the lower figure, and personally aim for 15-20%. Size to the following for both tube sizes-

Groove width 3.7-4mm, depth 2.1-2.5mm

[tomp]

Thank you Andy will have a look and get some ordered.

Done a little bit more not a lot of time at the moment slowly getting there

[tomp]

collected my next project today, makes my s class look very small

[spooksgone]

That's going to be one big model. I am pretty sure that the type 21's where mostly of welded construction, so you won't have to start knocking out about 38 thousand rivet heads. I had a 1/48th scale type 21, brought it from a guy called Maurice Rickett, fitted it with r and r tank's. That will certainley go well under the water, very stream lined. Nice. Where did you aquire it from?
Cheers
Phil

[U-33]

Maurice Rickett? Now there's a name from the past, Phil...ex Yorkshire policeman if I remember  correctly, he was in the AMS back when I first joined.

[Subculture]

It looks like the 32nd Parallel hull Andy Kiernan was flogging a while back.

Dave Wright has one of Maurices XXI's. Very nice boat- lots of detail. Was also originally fitted out with R&R tanks, but he decided to replace all the guts with a cylinder based ona  water pump ballast system.

[spooksgone]

Thanks for that Subculture. It's nice to know that some of Maurices boats are still out there, ans still going strong. Tomp has gone and got him self a real big project now!!! That will look fantastic when completed. Thanks again.
Phil

[tomp]

It looks like the 32nd Parallel hull Andy Kiernan was flogging a while back.

Dave Wright has one of Maurices XXI's. Very nice boat- lots of detail. Was also originally fitted out with R&R tanks, but he decided to replace all the guts with a cylinder based ona  water pump ballast system.

Yeah it was off Andy met him at the weekend he has a lot of subs to be working on. I tried the pump today on a Robinsons squash bottle, it filled it to half way then wouldn't pump any more, then the hose popped off the bottle shot off and I got soaked made me laugh.

[wullie/mk2]

an old friend of mine he was a submariner for 15 years,he  has a few subs, that i,d like to share with you,..they are all static divers,either Engel,or OTW...+ an early Krick,...his first, then after that,he went nuts, he has 2 x Seraph,whatever they are,2 x Gato,s,1 x Akula,...and a monster that has 2 x engel tanks side by side,and what looks like 2 x kort nozzle i forgot to ask what it was,here are some pics

[Subculture]

I tried the pump today on a Robinsons squash bottle, it filled it to half way then wouldn't pump any more, then the hose popped off the bottle shot off and I got soaked made me laugh.

Yep- 15 psi will half fill a bottle, but no more, so the manufacturers spec is spot-on. You have to vent the tank in some way to get more water in. OTW vent into the dry spaces. With that system you need probes or a float switch in the tank to ensure you don't pump water past the vent flooding the module.

The test you ought to try is, to fill the bottle with water, then see how much you can pump out, drawing a vacuum in the bottle.

[unseen]

Re Maurice Ricketts,

His Type XX1 mouldings were sold to R&R Model Engineering many years ago along with the Surcouf which OTW is now marketing.  The Type XX1 U boat was not detailed when Maurice sold them to Ron, in fact the hull was rather poor.  The hull and tower was remodelled and detailed by me during the nineties to what it is today.  Didn't know they were still around to be honest.

[Subculture]

Some of the hulls are still around, but the original tools were damaged I believe.

[unseen]

I just don't know about that at all.  I was asked to rework the hull and bow, which I did from Rossler drawings and close up photo's and detailed it in alloy plate.  After I gave it back to Ron he had new mouldings made and that was the last I saw of it, although I did see one of the first hulls from the new mouldings prior to being sold.

[tomp]

Slowly collecting bits and pieces for the WTC, looking for a decent fail safe any recommendations on one, needs to switch 12v if possible Cheers Tom

[Subculture]

Failsafes tend to operate an R/C channel, they don't switch power directly. Exceptions to this are some of the Subtech products- http://subtech.co/acatalog/SubTech_-_Products.html

Some products incorporate a failsafe directly. Also many modern receivers incorporate failsafes whih are programmable,  e.g. Shulze.

If you're planning on a system like the OTW module, then you might want contact Mike and ask him if he has one of these kicking about in his box of tricks-

http://microgyros.com/servo_ballast.html

Mike designed that for use with such a system, it has probes for full and empty on the tank, failsafe and can control a servo with microswitches or a speed controller to switch the pump, and valve. ou could use a pinch valve instead of a solenoid actuated valve, cheaper and smaller.

[tomp]

Made a quick test rig for the sub internals need to add in a solenoid, level sensor, fail safe, servos, 2nd motor and the mixer. Going to put it on a board and test it before installing it in a WTC. Tried a optical LED fluid level sensor but didn't work for some reason need to test it see what happened just run out of time.

[spooksgone]

Hi there Tomp. It looks like it is all coming together for you now, I take it that you are going to stand Subculture a pint some time then?
Cheers

[tomp]

Made a quick test rig for the sub internals need to add in a solenoid, level sensor, fail safe, servos, 2nd motor and the mixer. Going to put it on a board and test it before installing it in a WTC. Tried a optical LED fluid level sensor but didn't work for some reason need to test it see what happened just run out of time.

Yey got it working helps if you read the manual. Quick video of it working http://youtu.be/J_ZwVVTzgWA
now to tidy it up put it on a board and test it

[tomp]

Hi, need some help getting there but now I have come to the front torpedo tubes I am struggling with lack of space to work on it. I made a cardboard cut out to try get the correct shape but still can't get it perfect. I have been thinking about cutting the front of the boat off so I can do what I want then fibre glass it back on again when finished. Doing this is it going to make it weak at the front and could possibly break?

[spooksgone]

Hi there Tomp. That seems to be a bit of a drastic move. If you have to cut the bow off, you can all ways make a couple of bulk heads , one for each part of the hull end, the ones that will meet each other, fibre glass them in, and bolt them together. This will have an effect on the boat as the water will hit the bulk heads as it comes through the torpedo tube doors though. I will do a sketch in the morning if you like. Tired now, just had a thousand mile drive around the uk this week!!! some holiday!!

[Subculture]

Providing you glass it back together again, it will be very strong.

[Batfish]

Tom,

Pm Ken on Subcommittee.

User name is corsairman,
He built an S and a surcouf. he might have an idea regarding the torp/bow area. maybe even a template he could scan and email you for the correct shape...

http://s181686668.onlinehome.us/phpBB3/viewtopic.php?f=21&t=10589&p=63053&hilit=corsairman#p63053

[tomp]

Hi Batfish, yeah I have seen pictures of Kens S class, nice sub really good choice of colours. I am a member of the Sub Committee also so have seen Darrin’s build log on there again really nice build. It got converted to the OTW dive module from Darrin’s own I there is a video on you tube of it.
Still not sure how I am going to do the torpedo bulkhead yet but I have chickened out of cutting the front off. I will probably get a miniature contour gauge and build the front bulkhead, then slide it into the boat it seems the best way I can do what I want with it, we will see.
 You will not be disappointed with the kit it is very good, I will get an OTW type VII once I have finished the Type XXI so that might be a while yet. As for the module I’m trying to build my own I have had some great help from Subculture and Spooksgone without them 2 I would not know what I was doing, well that s a lie I would be parting with £860 and becoming a single man again!!
The motors are now sorted along with all the controls for the pump, failsafe, solenoid, level detectors and sump detector all works nicely.  Still hasn’t gone wrong on my little test bed for it so It’s now time to make the module just need the time to do it, most of my time is spent on a trampoline with my 2 year old little boy, loves the 'blinking!' thing but I have to be on there also! Cheers Tom
 

[Batfish]

Ah Trampoline... horrible thing's cheap poles and the safety net's are rubbish, break in next to no time. Good laugh when wind takes it and it flys past the window  

It's good to hear your getting thing's sorted with module and worked out your motor space issue.
Re the pump and probes, I'm sure andy mentioned microgyros and i'm sure mike at MG has updated it. Also subtech seems to be coming out with some new levellers etc. Might be worth a look at there web page.

I know what you mean about the Otw dive module, Not being rude to bob, but it's rather expensive for what it is!!

Have you sorted out a TX and RX??? I noticed a Robbe F16 on ebay for 200 quid seller had 8 avaliable.
Also worth checking Engel as they sometime's have good deals going on Graupner Mc and Robbe/Futaba gear.

Re, own module.. http://www.directplasticsonline.co.uk/PVCSheet  &  http://www.clearplasticsupplies.co.uk/acrylic_tube_clear.htm

I look forward to seeing more of your build Tom,

regards
adam

[tomp]

I have been lucky with our trampoline net is on the inside so can't get trapped in the springs and its really well built plus an added bonus was given it for free (I know I'm a cheapskate young family and wife part time that’s my excuse) I am going to use LED Optical fluid level sensors and my own relay board in the module, I can get these for £22. 2 types wet sink in the sump and dry sink in the module, they have a 12mm thread that will screw into the bulkhead and are self sealing due to the o ring on the end no other parts needed and cheap enough for me to afford plus they are good for 250psi. I have everything now for the module and total cost is just under £350 but I was lucky to be given a few parts for free which I owe Spooksgone a massive thank you for. I have a 6 channel 40mhz radio from a helicopter so I am sorted there thankfully can't afford another £200. I can kind of understand the cost of the modules they are very well built and a lot goes into the design of them I just can't afford it. It’s just this hobby is expensive, for the money I have paid so far I could of bought a Fleetscale kit with all the fittings and running gear, and electronics. But then it can't go under water!! Cheers Tom

[Batfish]

So have you worked out a ballast tank size as yet??
Are you placing the main batteries underneath your module??
Does the top of the module sit above or below the waterline??

[spooksgone]

I love this thread. Nice to see tomp getting on well, and it's nice to see every one helping out where they can. Whan it's finnished and at a show somewhere, I think we should all meet up and have a pint together???
Cheers all.
Phil

[tomp]

Yeah I owe a few people a couple of beers! Yeah getting there I hope by the end of the month building will be complete. Then the module that's going to be fun and frustrating also. Hi batfish module is going to be 120mm acrylic tube not sure on length yet nor how big ballast tank will be I have been told needs to be aprox 1.5 litres. Yeah module is under the water line and batteries might be in the front of the module to balance it out with the motors pump etc in the rear we will see how it balances out once all built. Have you picked up your kit yet? Cheers Tom

[Batfish]

Hi Tom,

Thanks for info re Module.
Could you not place batteries below module. Nimh stick pack, Maybe F cell's 12v 13ah.

Kit still being sorted out, Tower and casting's done. just the hull to go as far as i know. I believe propshop on hol's at the moment so perhaps running gear might be 2nd delivery.

When i emailed bob and jeff larue, they both confirm the overall ballast tank length of 305mm and 110mm/OD. Giving a total of 2.65 litre capacity.

I'm toying with the idea of a Hybrid system, possibly compressed air as Mbt and 2 piston tanks as Mtt. will watch how you get on with yours.
With overall ballast volume.

regards
adam

[tomp]

Hi Batfish, yeah I remember the waiting worth it though. Yeah I could put the batteries under the module but I wanted to add weight here to make it more stable. The top casing and conning tower are quite heavy and I wanted to use the batteries as a counter weight to the motors, pump, solenoid speed controllers plus also the rear skeg etc. Going to complete the build and then see how it all balances up. S class is going to be on hold for another weekend going on the Ace cafe reunion on Sunday and on to Brighton

[Subculture]

Will F cells fit? Big old batteries, and yes it's a big old hull. What's the width of the hulls keel I wonder? 13A is a lot of capacity, probably more than you need to be honest.