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[essex2visuvesi]

Just bought a Robbe Seawolf from a member on here which I plan to convert to Static diving

I'm thinking about using a simple rolling pump and Bladder type system where the Lead acid batteries used to live and replacing them with a 3 cell lipo pack located elsewhere

Has anyone tried usin this method before?

[Subculture]

Yes many times, the system works very well.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=25170.0

I would fit a pressure switch inline with the pump, especially with peristaltics, If the pump sticks on through a fault in the control unit, it will not only burst the bag, it will keep on pumping water compressing the air inside to dangerous pressures.

The cheapest pressure switch are the ones used in the Thundertiger Neptunes, which uses the same type of ballast system. There's a chap in the States selling Neptune spares, he also sells the switcher, pump, bladder etc. So you could purchase everything you need for the ballast system in one hit

http://www.ebay.com/itm/390315372178

[essex2visuvesi]

Big thanks for that!

I had downloaded the manual for the TT neptune and was going to use that system.... Never even crossed my mind to source the ACTUAL parts from a Neptune lol 

Anyways I now have a shopping list:-
Control PCB Neptune PJ6174
Sensor Pressure Neptune PJ6176
Sensor Leakage Neptune PJ6177
Motor Mount Neptune PJ6109
Motor Set 550 Neptune PJ610
Ballast Tank Neptune PJ6110

Prices up quite reasonably compared to other options I looked into which involved buying a bit from here another from there etc and I know its a tried and tested system :)

[essex2visuvesi]

Big thanks for that!

I had downloaded the manual for the TT neptune and was going to use that system.... Never even crossed my mind to source the ACTUAL parts from a Neptune lol 

Anyways I now have a shopping list:-
Control PCB Neptune PJ6174
Sensor Pressure Neptune PJ6176
Sensor Leakage Neptune PJ6177
Motor Mount Neptune PJ6109
Motor Set 550 Neptune PJ610
Ballast Tank Neptune PJ6110

Prices up quite reasonably compared to other options I looked into which involved buying a bit from here another from there etc and I know its a tried and tested system :)

Oh and the pump!

[essex2visuvesi]

Duly ordered along with the pump

next payday will be bayonet upgrade
http://modelluboot.de/Zubehoer/Bajonettver_e.html
or
http://www.piranha-modellbau.de/Preisliste.htm
Not sure what is best.... Pirana is a little cheaper and offer a tech tray as well which is tempting


And maybe later a subtech leveller

All in all that 80 quid bargain has turned out quite expensive lol

[Subculture]

The original drive system for the Seawolf was a Robbe Navy unit, a 500 size motor geared down about 3:1 I think, although the reduction may be a little less.

Anyway, I think the Neptune motor will work okay. The watertight seal will work well, something that is missing on the original Seawolf set-up which just used a greased stern tube.

One thing you might want to change is that double dog-bone coupling they use. Replace with a straight connector that bolts onto the motor shaft and propshaft. If you don't have a lathe, you can purchase these from Engel (not expensive), they used in the Lafayette and 212 kits.

A few other things to think about before you start glueing things together.

The Seawolf has a most peculiar front plane assembly- with a set of bow planes AND sail planes. No conventional subs I know of have this arrangement, they have one or the other, because hydroplanes induce a surprising amount of drag and noise, so you want to keep them to a minimum. Therefore I would fit only one set according to your preference, bow mounted planes work a lot better than sail mounted planes BTW. If you don't intend to articulate the front planes (and it's not really necessary with a boat of this type and size) I would leave them off altogether, the boat will run faster without them.

The tech rack and hull seal is the Achilles heel of all the Robbe submarine kits. Where the front bolt attaches to the tray is a weak spot that most modellers reinforce with some brass plate. The seal itself relies on axial compression. The o-ring supplied with the kit is especially soft and compliant, because you only have one bolt to compress the seal. When this seal  wears or splits, modellers tend to replace it with a normal nitrile o-ring, which tends to be too hard. This can result in a poor seal and leakage. Silicone o-rings are softer and will work well and can be purchased cheaply from places like polymax.

A better arrangement is radial seal compression, where the seal compresses against the inside of the tube. You can purchase bayonet rings, nicely machined from billet aluminium (I think they all come from the same source BTW). Certainly the Rolls Royce treatment, with the price tag, but you can achieve the same result with a turned plastic ring for beans, but you will need either good bench fitting skills or access to a lathe to make this item.

The Piranha tech rack is a fair old bit of ironmongery. It's certainly much tougher than the original, I'm not sure whether all that metal work will tinker with the radio reception. You could copy it by making some plastic discs and trays using polycarbonate or PVC sheet, and threaded studding from the DIY store. But really the original equipment tray is more than upto the job with a couple of subtle modifications.

[essex2visuvesi]

The motor I ordered is the motor for the pump (I hope), I already have the drive motor from the kit

Thanks for the heads up re the techrack, I do want the bayonet fittings tho.

Building won't start until I have all the parts to hand (Sub kit is in the UK still)

What's the best glue to use? I do have a selection of modelling glues (Humbrol liquid poly etc) and a selection of Expoxy glues (5, 30. 1hr and 4hr) but dont mind buying a specific glue for this model

[Subculture]

The boat is made up of ABS components with some metal parts. Robbe recommend Pattex Stabilit express, which is modified acrylic adhesive. It's expensive, but you can get other brands which works just as well for half the price.

Staloc adhesives sell a comprehensive range of acrylic adhesives, which have names similar to branded products-

http://www.shop4glue.com/acrylic-sga-methacrylate-toughened-adhesives-66-c.asp

For instance the Stabilit express equivalent is called Stable-xpress. He, he!

They also do some that don't need mixing, which look interesting (I'm assuming they're anaerobic), haven't tried those yet. I have used modified acrylics however, and I would say they are the best glue I've encountered. Totally waterproof once fully set (24 hours), sticks just about anything, and very, very strong.

A lot of submariners swear by 24 hour araldite. Do not use quick setting epoxies on anything that will be exposed to water, becuase the connection will soften and fail in time. I think the acrylics are better.

I avoid superglues. I find them brittle, and they can degrade some plastics over time. You can use solvent cement on detail aparts, ABS fuses well with itself and some other thermoplastics. I use plastiweld. The problem with solvent welding is that it's sometimes difficult to get a large area of bond, that's the advantage with thick goopy adhesives like epoxy and the some of the acylics.

[essex2visuvesi]

Cheers for the insight, I will get some ordered ready, always nice to have just the right tool (or glue in this case) for the job

[Subculture]

I would go for the super acrylate- http://www.shop4glue.com/superacrylate-10-min-set-acrylic-methacrylate-glue-adhesive-plastic-welder-abs-perspex-grp-metal-108-p.asp

You could ask them about the clear set stuff they do if you want clear joints. You should be able to bond the entire model together with that stuff.

If you want thicken it further, you can mix ground or milled glass and other fillers with it, which will also improve strength. You basically treat it like you would a resin.

[StarLocAdhesives/FiveStar]

They also do some that don't need mixing, which look interesting (I'm assuming they're anaerobic), haven't tried those yet.

Acrylics / Methacrylic adhesives are all accelerated slightly by anaerobic conditions so will usualy set between parts faster than in a mixing tub,
They can be formulated to come in different forms, unlike epoxys mix ratios are not very critical , epoxys need part a to be close to part b as the hardener is used up in the cure, with acrylics its similar but different...you only need to trigger the cure to a certain level for it to completely cure ( eventualy, usualy more catylist and the faster it will set but it may vary the strength )


common types are


1/
a bottle of resin containing all the structural components and part A of the catylist  , and a primer containing part B of the catylist ( not a hardener like in an epoxy ) , contact with just a trace of catylist will set the adhesive due to triggering a chain reaction polymerisation


2/
basicaly the same adhesive as above, but the resin is split ( with exact formulation ) between the two parts A and B , then the 2 components of the catylist are split between them, put a drop on both sides of parts to bond and when pushed together the two parts react and trigger the chain reaction , the components are identical in formula other than catylist so dont need blending to get a correct bond strength 


3/
The equal mix type, used like an epoxy , blended well before use, not due to the catylist parts needing to be mixed its due to one side cointaining different blends of monomers or other components that may be seperated for other reasons, for example one may react with one of the catylist components prematurely, they often ( but not always need mixing well, it depends if the parts are different resins or not! )


4/
Products like Stable express are like a type 2, but still sort of like a type 3...they need to be mixed together but not to trigger the cure , the powder has other components, that effect use / performance etc


5/
Anaerobic acrylics like threadlock, they contain the resin and both halves of the catylist ( 4 part catylist system ) , they are very air sensitive as the stabiliser in the bottle needs air present to absorb the free radicals that are trying to polymerise the adhesive, as soon as air is gone the cure accelerates , often formulated to need metal contact as well as abscence of air


6/
Cyanoacrylates, a type of acrylic and not realy accelerated by anaerobic conditions, they set by contact with trace moisture that neutralises the stabiliser , setting rapidly when in a thin layer , if a thick layer is needed you can add an accelerator to cure them quicker 

[essex2visuvesi]

next payday will be bayonet upgrade
http://modelluboot.de/Zubehoer/Bajonettver_e.html
or
http://www.piranha-modellbau.de/Preisliste.htm

So its time to open the wallet and make a purchase.
Does anyone have any experience of buying from these 2 sellers?
Both seem to be highly regarded.

[Subculture]

The first link is reliable. I purchased some peices of Norber a few years back and received them within about three days of purchasing.

Piranha I have not had any dealings with.

[essex2visuvesi]

I've been very restrained on this build as I want to get it right first time,

While waiting on delivery of the Bayonet fittings I decided it was time to make a start on figuring out where everything will fit in the WTC






This is layout plan 1.0, a tight fit but everything fits nicely. I plan to make a platform to mount the Front plane servo above the rudder/rear lane servo along with the leveller.  The ballast pump will also be mounted to a fabricated plate


I have encountered a small problem with my chosen Ballast bag, its too wide! and Im worried it won't fill properly.  I'm not sure if this will be an issue or not, but have a backup plan and will purchase one of these bags instead.
http://www.ebay.co.uk/itm/281034213703?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649,
This also has a larger volume so should be able to get away with less static ballast making the sub lighter to transport.  So if anyone needs the ballast bag from a TT Neptune let me know :)


After taking the picture I noticed that the ESC will need to be mounted on its side and not flat as in the photo otherwise it will foul the rudder contol rod.


If I have made some blindingly obvious faux pas, please feel free to heckle or laugh and point :).  This is my first sub so any pointers/recommendations greatly received.

[Subculture]

You can place the bag inside a cylinder. This cylinder should have a few holes drilled in it so it can vent as the bag fills.

This constrains the proportions of the bag, and prevents it shifting position inside the boat. The cylinder can be made out of a piece of plastic pipe (PVC, ABS, acrylic etc.)

The other option is to search for a large syringe and pump in and out of that instead of a bag.

[essex2visuvesi]

I had thought of that, I have ordered the larger bag and another member has taken the TT bag off my hands.
The new bag will be a better fit and will be mounted so it cant move about, more on that later.


Tonight the build will start :)

[essex2visuvesi]

Now I have TX working how I want I can start with the build.


Been thinking about servos.  Could I get away with using smaller servos? Current plan is to use Futaba S3003 servos but I have some smaller mini servos from My Trex 500 and was wondering if they would be OK.... gives a bit more room to squeeze all the gear in


These are the bad boys I'm thinking of....
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=13421

[Subculture]

9-10 gram servos or larger will be fine. The Robbe boat uses bellows, so low in friction, and it's a fairly modest size, so you don't need a lot of grunt for the controls. The kit dates back over twenty years when micro and mini radio still cost a premium.

The ones in the link are more than adequate.

[essex2visuvesi]

Thought they should be ok, but always best to check... gives a bit more room as I can fit them side by side, rather than staggered as per the instructions

[essex2visuvesi]

Unemployment does have its advantages..... can actually get some building done


Have started on the tech rack with a few mods
Main mods being a mounting plate for the TT Neptune Dive pump, servo mounts for the rudder and rear dive planes (The instruction suggest double sided foam tape which is something I'm not happy with)




Also fitted some reinforcement to the front screw mount as research suggests this is a weak point.



I did buy a CNC bayonet fitting, but have decided not to use it as it requires quite a bit of fettling of the tech rack to make it fit


Next jobs:-
Cut and fit a plate above the servo mounts to increase strength and mount the ESC.
Make a servo mount that fits to the front end cap for the front dive planes.


I had a change of plan on the battery layout..... I will now be using two LiPo packs of different voltages
A 2cell lipo pack for the drive motor and BEC and a seperate 3Cell lipo for the Dive pump.  Why? the battery pack I had purchased didn't fit too well and after some jiggery pokery th 2packs are a far better (and neater) fit other added bonus is that I had them in the battery stash so no further expenditure was required.

[essex2visuvesi]

Custom Front plane servo fitted and working.  These are connected via a Y lead to a leveller and the rear planes.  The leveller only acts on the rear planes
[size=78%][/size]



I will not be gluing the front cap to the Tube, instead i plan to machine a groove into the endcap and fit a rubber o ring to seal it.  This will access to the front servo easier.


Mini servos fitted into custom servo mount with the motor ESC mounted on top.  This design gives far more room and saves relying on double sided tape to hold the servos
[size=78%][/size]


The dive controller board from a Thunder Tiger Neptune above the main drive motor.... A cheap way to get into static diving!  Mounted on standoffs made from 6x6mm evergreen rod



I intended to have the dive pump here but it would have put most of the weight at the rear of the WTC


Final pic is the battery area, batteries sit on top (1 x 2600 3s lipo and 1x 2600 2s lipo) with the dive bladder underneath



Tidying up the wiring is the next mission.... not one I'm looking forward to!

[Subculture]

Better to have the forward vanes on an independent channel. You then use them to regulate depth, especially when near the surface. For a boat like the Seawolf, you could really dispense with them altogether. One point can you get to that servo easily once it's all fitted together, because the model submariners law says the most inaccessible part will also be the most failure prone!

I'd also advise keeping the ESC as far away from the RX as possible. It's an excellent ESC, but they still chuck out a bit of EMI, and on a sub you need all the help you can get with good reception.

When running your cables try and keep signal cables running down one side, and power down the other. Twisting the power leads together is a good, free way of cutting down on any parasitic induced interference. You can also do the same for the servo lines, but not essential.

[essex2visuvesi]

The front servo will have reasonable access as I plan not to glue the forward endcap as per the instructions, but to seal it with a rubber ring like the rear cap.


Thanks for the heads up re the ESC.  I went for the microgyros as it came highly reccomended. I can move it to the other end behind the dive controller.


Not sure what do do with the front planes now


Here is the current TX layout





So I'm thinking I should change it to this:-


or have I completely missed the point?

[Subculture]

That little rotary dial on the top right, does that control a proportional channel? If so, I would use that for the front planes, and keep the layout you have in picture one, but have the rear planes only hooked up to the right hand stick.

Regarding the front cap- sounds like a recipe for leaks to me, as you have doubled the failure points by incorporating a front seal too. Plus it's an area not easily inspected. Don't do it.

Personally I'd ditch the front planes altogether, and remove them completely from the hull. This simplifies the boat, and makes it run cleaner hydrodynamically (fewer control surfaces equals less drag).

Bear in mind that on modern subs, a lot of them have retracating front planes, and small boats like midget subs, Hollands etc. had none at all. You won't miss them. On a very large model, they do have some benefit when running near the surface, but the seawolf is small, so you won't notice.

I would also make every effort to fit the bayonet ring you purchased. The hull seal is the real weak link in these kits in my opinion, and the bayonet ring completely eliminates that weakness.

[sharkbite0]

hi essex
i have glued the front end cap on my seawolf as in the instructions. one less leak to worry about lol
also i have used metal geard micro servos for the dive surface's and moved them to the motor end of the tec plate.that has left a lot of room for me to fit a balleast system later.which is what im planning to do
i will post a pic of my set up later to day when i have the pressure hull opend up and post on here if thats ok with you mate.
regards
mick