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Author Topic: British S Class  (Read 40897 times)

spooksgone

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Re: British S Class
« Reply #100 on: September 02, 2012, 01:36:18 PM »

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
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TomP

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Re: British S Class
« Reply #101 on: September 02, 2012, 10:31:57 PM »

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
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16-21

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Re: British S Class
« Reply #102 on: September 03, 2012, 01:00:42 PM »

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
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TomP

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Re: British S Class
« Reply #103 on: September 03, 2012, 08:34:26 PM »

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

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Subculture

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Re: British S Class
« Reply #104 on: September 03, 2012, 08:37:48 PM »

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.

TomP

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Re: British S Class
« Reply #105 on: September 03, 2012, 09:12:33 PM »

F's would not fit, C's would but the module would need to be raised slightly to get them in. Plus getting at them with the module in place would be a pain in the @#%^. Maybe you could put the battery's in where the saddle tanks would of been on the side of the module. Weight is quite high then though not sure if it would cause stability problems?
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Subculture

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Re: British S Class
« Reply #106 on: September 03, 2012, 09:31:37 PM »

Why would you need to get at them though? The power leads run round to the front of the dive module (assuming you're mimicing the OTW arrangment) , so you just hook them up to the charger in situ. You can get 5A capacity cells, that should be good for over an hours running time providing your drive motor(s) are efficient.

16-21

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Re: British S Class
« Reply #107 on: September 04, 2012, 11:24:22 AM »

Tom,

Nice R1!! wish i still had mine, decent bike but front end a bit to light!!! wheelie happy thing!!!
Ok when you mean to do it on private ground.... but scary at silly speed on rough patches.... Private track again.

Atleast that one does not have the weird pink/red frame.

Pity about the F cells, i would of thought that overall length of 900mm would have fitted in underneath, is it the height issue with module??

C cell, 25.2mm dia / F cell, 32.2mm dia

adam
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TomP

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Re: British S Class
« Reply #108 on: September 04, 2012, 12:00:14 PM »

Hi Adam, Thank you yeah it is quite smart, so fast. I changed it for my R6 this year which I have had for 6 years I was a bit gutted to see it go. Did a tour around France this year covered 3k miles on it so got used to the power it has over the R6. I have hit the rev limiter in 6th gear which was very very fast 186mph (track obviously). It is quite light but Iím used to it as the R6 was very light on the front, I didnít have a steering damper on that wish I had at times ,cats eyes and hard acceleration = change of pants. Thankfully this has one not so scary under hard acceleration.
I will take some photos for you later show you what I mean itís easier to see why rather than describe it. I have 100mm tube and 120mm so will show both. Cheers Tom
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Subculture

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Re: British S Class
« Reply #109 on: September 04, 2012, 01:14:25 PM »

You might want to look at Lithium LiFEPO4 batteries. These are available in cylindrical and flat cell styles. They come in various diameters, and are slightly higher energy density than NimH. You do need a charger designed to be used with LiFE batteries, fortunately these are becoming more common now than they once were.

Ebay is a good source for these batteries, you will almost certainly have to order from overseas though, as availability in the Uk is a bit shabby.

16-21

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Re: British S Class
« Reply #110 on: September 04, 2012, 04:41:34 PM »

Change of pants lol. Come close to doing that 1st time I had a tank slapper. 
Friend of mine was on back of r1 filtering through traffic, his eye's where on stocks bricking it. I still remember him saying mum....

Give him a lift on blackbird back in march ruddy cold here that day punch the ice of seat, I thought I would have to wash the seat down after he on back.... Lol.


Is it not feasible then to fit nimh batteries within wtc? If your tight for space... Check grimreaper vanguard and rameshs tireless build. Thats where I got idea of seperate motor wtc.

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TomP

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Re: British S Class
« Reply #111 on: September 05, 2012, 09:15:41 AM »

I always wanted to have a go on a Blackbird, guy next door had one and raved about it.

Pictures of batteries and tube in the hull, only had type D batteries





These are with a 100mm tube over the batteries 1m long







These are with a 120mm tube over the batteries 1m long







These are how I am going to do it, 120mm tube laid on the hull so the top of the module will be level with the water line (not sure if thats a good thing or bad thing??) The 100mm tube I won't get the 2 motors side by side, I could do as you said Batfish but its more tubes to make water tight so I wanted the minimum amount of failure points as possible.







The reason I don't want to put the batteries under the module mainly is that I would have to buy new battery packs, I have 3 sets of 12v 5000mah packs from Component shop for my 1:24 Perkasa so would like to use these in this also, I can't afford to buy more at the moment spent all my overtime money on the parts for the WTC and another sub (XXI) DOH!!
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salmon

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Re: British S Class
« Reply #112 on: September 05, 2012, 04:39:37 PM »

Is your sub cut at the waterline? If so, then your WTC will be higher than the waterline and a liability rather than an asset for buoyancy (not sure what reserve you have in that so please forgive my ignorance). Without the batteries in there, does it lower your WTC closer to the waterline? Just some thoughts.
Peace,
Tom
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Subculture

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Re: British S Class
« Reply #113 on: September 05, 2012, 05:14:28 PM »

If the cylinder projects above the surface of the waterline, it means a bigger ballast tank. It does tend to improve the sea keeping ability of the boat when on the surface especially if you're sailing in choppy water. It also tends to help increase the metacentric height of the boat as it submerges, by raising the centre of buoyancy.

Generally as we like to keep ballast tank volume to a minimum, it's considered best practice to keep the cylinder below the waterline where possible, but don't sweat it too much if that doesn't work for you- after all fullsize boats tend to have a pecentage of their pressure hulls above the waterline when surfaced.

TomP

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Re: British S Class
« Reply #114 on: September 05, 2012, 09:32:54 PM »

Well the water line is a bit of a pain because it starts below the top torpedo tube at the front and angles down to the bottom of the top casing at the rear. But when the sub is submerged it's level. The module will be level in the hull, the front of the tube is 20mm above water line at the Center of the hull it is level and then at the rear it will be 20mm under the water line. Glad it doesn't cause to much of a problem. Had the discs for the WTC machined today with a groove for the O ring. Question could this be secured in the groove with silicone? Cheers Tom
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TomP

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Re: British S Class
« Reply #115 on: September 05, 2012, 09:42:07 PM »

Is your sub cut at the waterline? If so, then your WTC will be higher than the waterline and a liability rather than an asset for buoyancy (not sure what reserve you have in that so please forgive my ignorance). Without the batteries in there, does it lower your WTC closer to the waterline? Just some thoughts.
Peace,
Tom
Hi Tom, no the cut is below the waterline, it looks as if part will be above and the majority will be below the waterline. I have taken the batteries out from under the WTC to try get it lower in the hull cheers Tom
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salmon

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Re: British S Class
« Reply #116 on: September 06, 2012, 01:39:30 AM »

It is a beautiful sub, regardless of the location of the wtc. Look forward to seeing this sail! Someone mentioned LiPo batteries, I use them, but might be changing to LiFe batteries. You have a lot of options don't you?
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Subculture

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Re: British S Class
« Reply #117 on: September 06, 2012, 10:50:53 AM »

Had the discs for the WTC machined today with a groove for the O ring. Question could this be secured in the groove with silicone? Cheers Tom

Why would you want to do that? Just let it sit in the groove without adhesive, when you button up the seal compresses. if you bond it in, it makes it difficult to change, and you will need to replace at some point. If you're using axial compression of the seals, you may want to consider using silicone o-rings instead of nitrile. Unlike nitrile, the usual choice for o-rings, silicone is pretty much inert to o-zone, this means you can leave them exposed to the air and they don't degrade. The disadvantage with silicone is it's more fragile than nitrile, and you have to be careful what lubricant you use on them. You shouldn't require any lubricant with axial compression of the seal, and silsicone o-rings tend to be softer, so they 'squish' up better.

Polymax.co.uk supply silicone o-rings. They have a £10 minimum order, so get all the seals in one hit.

Regarding the slanted surfaced waterline versus the level submerged position. The early Holland boats took this to an extreme, with a pronounced bow up attitude when surfaced, and level or perhaps a little bow down when submerged. In the case of the Holland boat, this was achieved by offsetting the position of the main ballast tank, positioning it forward so that with it empty the vessels C.G is aft of the centre of buoyancy. With the tank flooded the C.G moves forward, and the boat levels off.

Unfortunately different water densities, will have an impact on your submerged trim. So how do you deal with that?

Well if you're using a single main ballast tank like the OTW system, you can add a means of weight shifting, or fit auxillary trim tanks.

In the case of the afore mentioned Holland class boats the boat had a smaller ballast tank used for trim. The main tank was completely flooded,  and then the smaller tank, which was positioned directly over the submerged C.G, was used to adjust the final few pounds of buoyancy.



Thus the boat could be adjusted for differing water conditions without upsetting the longtudinal trim. Water density only varies by about 1-2%, so this tank can be very small compared with the main tank. All the submarines I've looked at use main and trim tank systems, in models this is rarely followed, as it means building two separate systems independent of one another, so the trim and main tanks are usually merged into one system. In the case of the Piston tank/Engel system, the trim can be very accurately set, but you still require two tanks to permit accurate positioning of the boats longitudinal C.G.

In the case of a boat like your S-class, a trim tank would need to be about 120-150 ml assuming you're using a 12cm diameter cylinder 100cm long. Another alternative is to make a sliding tray for one or more of your battery packs, and couple this to a servo, so you have a proportional method of weight shifting.

Another method sometimes used is to have a small set of trim tanks mounted fore and aft, these are coupled together via a reversible pump (peristaltic or geared), with a fixed quantity of ballast pumped fore or aft to modify the boats angle. This is closely follows fullsize practice, on small submersible craft, mercury is often used, larger boats pump water. For a model, I think shifting the battery is better, because it's easier to implement, and it's totally proportional and therefore easy and repeatable to control.

spooksgone

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Re: British S Class
« Reply #118 on: September 07, 2012, 08:18:32 AM »

Wow, that's cool.  lot's of food for thought there Tomp.
Cheers Subculture.
Phil
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spooksgone

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Re: British S Class
« Reply #119 on: September 07, 2012, 08:39:42 AM »

I just had a rumage through the work shop [garage] I have a peristaltic pump if you, or any one else needs it. Could you not use the fuel tanks the the model fly boy's use in thier aircraft as trim tanks? Just a thought, not my strong point I know!!!
Cheers
Phil
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Subculture

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Re: British S Class
« Reply #120 on: September 07, 2012, 09:38:47 AM »

If the tanks are placed within the pressure hull, then model aeroplane fuel tanks could be used. In the free flood area they may be a little too squishy under pressure, as these tanks will incorporate an air bubble. If the tanks are going in the wet, then you could make some tanks out of PVC or acrylic pipe. If possible mount them end up, this keeps any sloshing to a minimum, although with small tanks this is less of an issue.

But I wouldn't bother with this system, shifting the battery pack is easier.

TomP

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Re: British S Class
« Reply #121 on: September 07, 2012, 10:38:58 AM »

Wow, that's cool.  lot's of food for thought there Tomp.
Cheers Subculture.
Phil

Hi Phil, yeah too many options! still itís good to be able to pick and choose what's best for me and like you said it's great having people who have a lot (and I mean a lot) more experience than me. I read in one of the Subcommittee reports about Ken and his S class, seems he really enjoyed ballasting the sub..... NOT!! Seems the top is rather heavy making it want to roll, still like he did persevere and it will work. 

I do have a spare fuel tank from my helicopter crash but like Subculture says it is quite soft we will see lots and lots of options need to try a few see what works best

Hi Subculture, Thank you once again for your knowledge, I like the idea moving batteries instead of another container because that would mean another pump plus controls for it, got to think of the pennies.

Little boy thought he would help by using a wire brush on the hull, nicely scratched now!! Still he was only trying to help. Cheers Tom
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Subculture

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Re: British S Class
« Reply #122 on: September 07, 2012, 11:11:18 AM »

Etched brass deck doesn't help matters with regards to stability, but you have a big wide hull so plenty of scope for building instability if it's required.

Can't claim any credit for the battery shifiting idea, it's all in black and white in the traplet publication Model Submarine Technology. There's a chapter that covers this subject in that book and it includes a simple formula that enables you to quickly calculate how much ballast you need to shift and how far to get a certain angle of tilt.

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Re: British S Class
« Reply #123 on: September 07, 2012, 11:48:30 AM »

Hi Tom,

Do u want me to email u the 3 build info of kens?

Looking at 1 of the pic's otw place battery beneath and modul sits very high as a result,
Perhaps that why the ballast tank is the size it is.

Anyone else want the S class build pm me.

Regards

Adam
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Subculture

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Re: British S Class
« Reply #124 on: September 07, 2012, 03:51:17 PM »

Another technique to consider, is placing some buoyancy (e.g. foam, a tank etc.) in the stern of the boat, and above the waterline. As the boat submerges this will move the centre of buoyancy forwards, so that the boat takes a more level attitude. The size of tank/foam will require some experimentation to get right, but this is the lowest tech solution to the problem.
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