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Author Topic: OTW Vanguard help  (Read 78515 times)

merriman

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Re: OTW Vanguard help
« Reply #275 on: February 25, 2012, 12:19:00 AM »

Ferric Chloride. Same stuff they sell for acid-etching/cutting circuit boards and PE part frets. Warm it up a bit, dunk the part and scrub it with a brush (acid-brush ... duh!) till the metal turns dark, oxidizes. Pull out of the acid, put into some soapy water, scrub with the brush but do not polish. Dry, prim and paint.






















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Re: OTW Vanguard help
« Reply #276 on: February 25, 2012, 07:04:24 AM »

Dunno if you can get that window sticker stuff over here. You can get builders scrim, that works well.

Etch primer has acid in it already, so it does the etching and priming in one hit. You can get 1k Upol etch primer in aerosolf form from Halfords, quite expensive (about a tenner for acan), but you only need a little bit, so a can will last a long time.

Dave's method works well too, but be warned Ferric Chloride will stain anything it comes into contact with, clothes, furniture, skin etc. So make sure you wear an apron old clothes when using it, and work somewhere non-critical to domestic harmony. Silicone bronze will end a bit more of a dunking than white metal.

thegrimreaper

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Re: OTW Vanguard help
« Reply #277 on: February 25, 2012, 02:07:33 PM »

I wouldn`t know where to get Ferric Chloride from not seen it on the shop shelves over here they have all the fun in the U.S. will use an etch primer. as to the scrim we got builders on site where I work so I will ask a Bob the builder for some but I dont know how well black will show up on dark volvo gray will give it a try anyway, if I have to repaint then so be it cant have it not looking right can we.

Regards Mark
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Re: OTW Vanguard help
« Reply #278 on: February 25, 2012, 03:05:43 PM »

You can get Ferric Chloride from Maplins, Rapid and other electronics warehouses. It comes ready mixed, or in pellet form where you mix it with water and store it in a plastic bottle

thegrimreaper

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Re: OTW Vanguard help
« Reply #279 on: February 29, 2012, 06:51:10 PM »

New test tank was picked up today .................................and inflated



Then filled with H2O     :D O0 :D

Balance of the Vanguard is not to bad need to add about 700gms to the rear of the sub to balance her then going to slowly add weight to her midships to get her down to the correct water line took two photos of her in the test tank ................






no leaks at all on the front and rear chambers  BUT found a tiny leak on a  seam of the ballast tank which I have resealed lost the light now so will start again on Monday now

Regards Mark
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merriman

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Re: OTW Vanguard help
« Reply #280 on: February 29, 2012, 07:04:16 PM »

Did someone delete my post here?

David D Merriman lll
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thegrimreaper

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Re: OTW Vanguard help
« Reply #281 on: February 29, 2012, 08:28:12 PM »

Didn`t see a post from you David.
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Re: OTW Vanguard help
« Reply #282 on: February 29, 2012, 08:59:56 PM »

Will that larger forward compartment will move the centre of buoyancy too far forward I wonder? You may need to put some foam in the stern to bring it in line with the centre of gravity.

thegrimreaper

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Re: OTW Vanguard help
« Reply #283 on: February 29, 2012, 11:04:50 PM »

I have put 700 gms of lead into the stern of the sub and that got it to sit level but the water line was well off. I will have to sort out some lead sheet for under the ballast tank to get the sub to sit at the correct water line was not enough weight in the sub at time of test for a compleate dive plus the top was off hopefully the next test will rectify any problems

Mark.
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Re: OTW Vanguard help
« Reply #284 on: March 01, 2012, 09:52:44 AM »

Adding and moving the lead about until the boat sits level on the surface will align the centre of gravity with the centre of buoyancy. The latter is most likely forward of where you want it to be, because the forward cylinder is longer than the rear cylinder. So it will look fine on the surface, but might go pear shaped once you fill that ballast tank, because that will shift the centre of gravity aft, and throw out the boats trim.


The large lead acid battery up front will help you out though. they weigh far more than they displace. So you will need more buoyancy up front to compensate for that.

You'll find out one way or the other when you fill the tank to take it under. If you look at the commercial cylinders, the compartments are almost always of equal volume e.g. your Sheerline Akula. So much of the hard work has already been done for you.

You get the position of the centre of gravity with the boat on dry land. You can hang a piece of string underneath the boat like a sling, aligning with the centre of the ballast tank- if the weight distribution is correct, it should balance at that point. Tricky hanging a boat this size, but you get the idea.

With the boat in the test tank, flood ballast and observe the boat. If it isn't sitting level you will need to add foam or some other form of buoyancy below the waterline to compensate.

thegrimreaper

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Re: OTW Vanguard help
« Reply #285 on: March 01, 2012, 10:10:11 AM »

Fantastic explanation of how to ballance the sub, greatly received Andy, work has had to stop now until Monday/Tuesday due to work getting in the way

      Mark
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thegrimreaper

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Re: OTW Vanguard help
« Reply #286 on: March 01, 2012, 09:49:50 PM »

Thinking about your hanging a large boat from a sling probably better to ballance boat on a peice of dowl on a flat table you would get the boat to ballance that way

     Mark
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Re: OTW Vanguard help
« Reply #287 on: March 01, 2012, 10:22:52 PM »

Helmut Huhn in Germany has an interesting way of mounting his subs- notice they're balance at the C.G point-

merriman

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Re: OTW Vanguard help
« Reply #288 on: March 02, 2012, 01:10:02 AM »

(deleted, I got stupid)
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timsenecal

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Re: OTW Vanguard help
« Reply #289 on: March 02, 2012, 05:12:12 AM »

septuplets?
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Re: OTW Vanguard help
« Reply #290 on: March 02, 2012, 10:07:21 AM »

He's been building those boats since the 1960's (nothing is really new...). Saw an article in a an old issue of Model Boats magazine from about 1968 I think it was, and it was about these subs, although there were fewer then. The boats feature high levels of automation, so he can sail several at once from one transmitter. Control looks like it is reed based- note the banks of relays!

There is lots more to see at the link, not much text, but plenty of nice pictures. Worth going to the home page and taking a gander at some of the other stuff there too.

http://www.ubootmodelltechnik.de/helmut_huhn.htm

thegrimreaper

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Re: OTW Vanguard help
« Reply #291 on: March 05, 2012, 02:15:51 PM »

Right I have just been to the scrap yard and bought what feels like a 100 weight of lead  %% bit to much weight if you ask me has anyone got a rough guesstimate of what a vanguard should weigh in at only roughly now I know I have built the wtc non standard and I will have to allow for that also in an earlier post it was mentioned that I may need to put some foam in the rear of the sub bellow the water line to compansate for the front chamber of the wtc if that is so what foam do I use ? can I use the foam that they wrap pipe in ??
thanks in advance

Mark
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Re: OTW Vanguard help
« Reply #292 on: March 05, 2012, 04:18:11 PM »

Because it's a wet hull, the amount of lead needed depends on the size of cylinder used, so it will vary from Vanguard to Vanguard, even though they're the same size boat.

The easiest way to get a pretty accurate estimate is to first calculate the volume of your cylinder- 3.14x cylinder radius squared x cylinder length.

Your cylinder is 10cm diameter, not sure on length, but it looks about 90 cm so I'll use that figure as an example.

3.14x25x90= 7065 ml displacement or 7.1 litres. 1 litre equals 1kg (metric makes things so simple) so that's 7.1kg.

Weigh the cylinder with all it's components installed, lets say it weighs 2kg with everything plumbed in, then subtract that from the 7.1kg. Subtract a further 0.5kg to allow for the extra density of the GRP hull, and you will also need to factor in the lead acid battery which will weigh considerably more than the water it displaces. I don't know what figure will be, but it's easy to calculate- area of base times height, all in cm will give you the batteries displacement in ml. divide that figure by a 1000 to give you a figure in litres.

Weigh the battery in kg's, and subtract the displacement figure. Lets say the figure you get is 0.5kg.

So for our hypothetical cylinder, we have 7.1-2-0.5-0.5= 4.1kg of lead

This is gross simplification, because there are many things I haven't factored in, like the heavy metal propulsor at the stern, the external tie rods, and even the displacement of the lead weight itself, but it gives you an idea of what you need, and you should get a figure between 10-15% of what you need.

Regarding foam, most people use the closed cell pink or blue coloured foam, it's quite firm to the touch. But there it's quite likely you won't need any.

All the above assumes the cylinder sits completely below the waterline when the boat is surfaced. Anything that sits above will reduce the amount of lead you need in the keel.



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Re: OTW Vanguard help
« Reply #293 on: March 05, 2012, 04:47:30 PM »

I think I've posted it before, but I'll post it again as it's a very useful link that allows you to quickly and accurately calculate all kinds of volumes, including some really tricky shapes, like ellipses, truncated cones and even barrels. Saves a lot of time.

http://grapevine.abe.msstate.edu/~fto/tools/vol/index.html

The old saying of rubbish in, rubbish out applies, so you need to be careful any numbers you put in are correct. I use cm for all my measurements, and the results given back are in millilitres (ml).

Patrick Henry

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Re: OTW Vanguard help
« Reply #294 on: March 05, 2012, 04:53:53 PM »

Mark, should you need any blue foam, give me a shout, I have loads of it here.
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thegrimreaper

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Re: OTW Vanguard help
« Reply #295 on: March 05, 2012, 05:12:58 PM »

Thanks Andy I worked out very roughly and got to about 4Kg`s. Think I bought to much lead ah well it will go into the Traf when I start her. so if the weather is nice tomorrow then the test tank will be re inflated and filled and the real testing will begin O0. thanks for the offer of the blue foam Rich I will let you know if I will need some thanks again for the offer

Regards Mark
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Re: OTW Vanguard help
« Reply #296 on: March 05, 2012, 05:25:02 PM »

You may need to add foam and more lead to get it stable.

Patrick Henry

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Re: OTW Vanguard help
« Reply #297 on: March 05, 2012, 05:37:48 PM »

Thanks Andy I worked out very roughly and got to about 4Kg`s. Think I bought to much lead ah well it will go into the Traf when I start her. so if the weather is nice tomorrow then the test tank will be re inflated and filled and the real testing will begin O0. thanks for the offer of the blue foam Rich I will let you know if I will need some thanks again for the offer

Regards Mark

No worries Mark, I had a stack of the stuff given to me, so if it helps you out...I'll give some to you.
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bonehead

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Re: OTW Vanguard help
« Reply #298 on: March 05, 2012, 07:08:50 PM »

When we were trimming mine, with the immense help of Dennis Pond, we found it would go down parallel fine to the top of the tower and just that bit of bouyancy from that mad it go down stern first - it tokus a heckof alot of head scratching and moving a tiny amount of lead around to get it right - then low and behold the minute it was in water a tad higher in temperature than that we trimmed at, it went out again. My battery is up front, is a gel type Yuasa of 12 volt, 3 amp approx - I chose this as it was a tad smaller than my original 4 amp one that stuck up above the water line - the lower curent one is just below the water line but we had to compromise and have the water line a bit lower than I would have liked. If I was doing it again, and I may do a refit sometime, I'd choose a smaller diameter WTC, but slightly longer to keep the tank volume, just to get as much WTC below the required water line and more importantly get the batteries either below or inside the wtc...... I think this design suffers from its length against diameter  - long 'n thin, and the tower not being more central. I think mr Sheerline had similar issues with his Ohio?? I am lead to understand it is in drydock being looked at presently?? Incidently my WTC is a bog standard OTW one which I had an increased volume water tank fitted to because of trimming issues.....!

Good luck and I look forward to sailing with you at the next Dive-in. Andy - when is it??
 Cheers
Jim



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Re: OTW Vanguard help
« Reply #299 on: March 05, 2012, 08:20:01 PM »

I'm sorry I can't commit to any dates for a Dive-in at the moment (had many enquiries already). This is a busy year for me- all got to do with some obscure sports event taking place in London!

If there is a Summer event, it will be more modest than last years event, and it's also likely to take place at a different time, because quite a few show dates have been moved forwards this year for some reason and June is now packed with dates!

Regarding the trim issues with the Vanguard, Dennis knows his onions, but are you sure there is no air getting trapped underneath the deck?

Failing that, a servo controlled weight may be the answer, don't think you'd need much.
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