Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Submarines => Topic started by: Jack D on December 04, 2014, 10:46:47 pm
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I recently decided to buy a new model boat which I could build relatively quickly and have few hassles transporting (when your fleet consists almost exclusively of 5ft ships and you have no car, getting out to sail can be tricky). I've also liked the idea of RC submarines for a very long time and it just so happens that Engel's Type 212A submarine neatly fits the size requirement.
It also boasts that it is easy(ish) to build. I will test if the instructions and kit are idiot proof, because I have no experience of subs whatsoever, apart from a couple of hours playing with another 212A and getting a very good impression.
I purchased the brushless drive version of the submarine set which was released in November, along with the Hall Effect Sensor upgrade. First impressions are very good, with the kit coming pre- painted (though I will be adding considerably to it), perspex windows covering navigational light details already installed, all of the rudder linkages already in place and a really nice magnetised aft hatch for access to said rudder linkages.
So far I've only had time to do a basic inventory of the parts but it seems that everything is in order. Work will begin in earnest on the weekend. Here is a photo of what you get in the box.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0946_zps734f4c9e.jpg)
Wish me luck- I'm going to need it!
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That's a nice kit, you'll enjoy the building and the sailing...keep the build log going, and plenty of pictures are mandatory!
Rich
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I will be following this with great interest Jack. Very well engineered, good instructions, but I became a bit stuck on mine a couple of years ago so would appreciate lots of photos and info, especially on assembling the three hull mouldings. ie epoxying the bayonet-ring section to the long hull section.
I have seen one sailing, very quick and agile.
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Nice photograph - It looks like an early Christmas!
Enjoy the build and let us know how you get on.
David F
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The men you need to ask questions about this kit are Ramesh (Wheelerdealer) and Andy (Subculture), both members on here.
Ramesh has built a 212A so he'll know all the answers to those little problems you may come across, and Andy knows all about bayonet fittings.
Rich
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Looks like an assembly job rather than a traditional kit. I don't think Engel could make it any easier could they?
It's a fantastic performing model. I would advise dialling the throttle down a bit as it's you first submarine, these get a lick of speed up on brushed power, so on brushless they should be even livelier and you'll find it easy to scuff up the nice paint finish when you're learning the controls. If you've done any model flying, then you might fin it easier to control, you tend to 'fly' this boat rather than sail it.
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First of all, thanks to all of the replies and advice posted in this thread so far. While I might not be able to respond individually to all of it, rest assured it is all being taken on board. Who knows, it might help other people browsing the thread in the future too (hello future people!).
I will be following this with great interest Jack. Very well engineered, good instructions, but I became a bit stuck on mine a couple of years ago so would appreciate lots of photos and info, especially on assembling the three hull mouldings. ie epoxying the bayonet-ring section to the long hull section.
I have seen one sailing, very quick and agile.
I've also seen one sailing and I've had the pleasure of sailing it as well. They are very fast- especially as you get to periscope depth and the rounded bow becomes more efficient (whereas of course a pointed bow works best running at the surface and less well underwater). This brushless version should be able to easily beat 10kph submerged. Of course I bought the brushless version for a longer running time so I'll be using the bare minimum of available throttle (most of the time- surfaced the extra power might come in handy and the underwater rocketship could be fun after a bit of practice).
As to the bayonet lock ring, this version of the kit comes with it pre-installed and lubricated. I also believe it's been pressure tested. I have taken some photos if it helps, but as U-33 already suggested it is probably best to ask other people with more experience. As Subculture said, this IS an assembly job. While I don't have much experience with traditional kits either, I do have a couple that I inherited and are waiting for my skills to develop and this submarine arrived much further along, with all of the watertight bulkheads already installed it seems. Which I'm grateful for- I wasn't relishing the prospect of installing watertight bulkheads. That being said, I don't want to give the wrong impression. This is not an Almost Ready To Run boat by any stretch of the imagination. A great deal of wiring is required and some amounts of construction.
Below are pictures of both the bow and stern O-ring mounts in situ which at least shows the way they're orientated on this model (whether you could have them another way I don't know).
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0954_zps579b9517.jpg)
Stern locking ring
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0956_zps3c719ba1.jpg)
Stern ring alignment
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0957_zpsceba45bf.jpg)
Bow locking ring
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0955_zps97ce73cd.jpg)
External shot of the locking ring.
On to today, I started work on the kit this evening after recovering (slightly) from the most vicious cold I've had in years. It was all pretty basic stuff, assembling the battery compartment, fitting said compartment to the piston tank and putting the pressure switch in place with associated brass and tubing. The two tubes with nothing attached yet are used as handy routing for power cables from the batteries at the bow to the electrical systems in the stern. The first potential flaw I've seen with the kit is where the tube to the ballast tank is routed, cutting access to the battery compartment in half which could make completely removing the batteries for recharging potentially problematic, but I'll have to cross that hurdle when I get to it. So far I'm impressed by how well everything goes together- the only hiccup was the routing holes for cable runs were out of alignment by about half a millimetre and needed some filing.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0950_zps8778a025.jpg)
Battery compartment assembled and attached to the piston tank. The unit at the opposite end to the piston is the pressure switch.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0952_zps8df1272d.jpg)
With various routings for air, water and power cabling installed.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/DSC_0953_zps487f3ce3.jpg)
Finally an image of the same unit as above but flipped so you can see the reverse. Maybe it was because I was tired, but I was initially stumped as where this water line should be routed going from the photo in the manual. I think it took reading the thing five times to finally realise it should go into the piston tank, which was clearly stated in writing.
I'll try to get a bit more done in the weekend proper.
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Don't forget there is also a nice article by John Parker on this build in "Model Boats" September 2013.
Lot's of detail on finishing, trimming and sailing with no major problems in construction you will be pleased to note!
Enjoy the build.
David F
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I've heard about that article before- I should probably have a read of it!
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Yes, I must admit I'd forgotten about even though it is only a year ago!
I found a reference to it by searching on the AMS Forum and then realised I had kept a copy.
Pm me if you have problems finding a copy.
David F
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As to the bayonet lock ring, this version of the kit comes with it pre-installed and lubricated. I also believe it's been pressure tested. I have taken some photos if it helps, but as U-33 already suggested it is probably best to ask other people with more experience. As Subculture said, this IS an assembly job.
Sounds like Engel have done some major improvements to the 212A kit. Having the hull sections effectively built and pressure tested is a real boon. Maybe customer feedback encouraged the hull upgrade. My problem is that it's not clear how the ring is epoxied in to get the right 'locked' orientation. A wrong guess . . . Fatal !
Apart from that it is incredibly well made, and as you've said it goes like a rocket. Once I can get the hull parts problem solved I look forward to completing it.
Bob K
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Looks like a lot of the tricky work is done. I still would have liked to seen them selling a full kit version. I will be interested to see how the sub performs with the new power plant.
Do you know what paint is used for the hull? You will be needing some to touch up the bottom hull due to scrapes etc...
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They still do the regular kits with the brushless propulsion as an upgrade- I believe if not bought in a set they don't have the same level of pre construction.
I'm glad this set already has had a large amount of work done to it- as my first submarine (indeed, my first Kit boat built from the beginning), I wouldn't be too confident in some areas and the progress would be very slow.
The colour is referenced in the manual- I think it may be an uncommon shade so you'd have to get some made up. I will probably be buying a durable aerosol version to touch up scratches etc on the bottom from a local paint manufacturer.
I've been working on the sub quite a lot this weekend- the piston unit is assembled as is the servo tray. I'm currently constructing the main power plug which will be able to isolate all of the batteries at once, which will be handy for powering up and down at the lakeside. My only niggling feeling so far is about the pressure switch- so far there haven't been any instructions to wire it up and I get the feeling I'll need to sacrifice another servo extension lead to do it. Photos will follow, I haven't had the time to do a detailed report.
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I've again been at work on the sub today. I've been sorting out the power distribution system today and now there's one plug to easily disconnect everything, so the batteries can be arranged nicely and plugged in to the tech rack and left for a while before operation (the original intention was for the port to act as a single charging point for the receiver and drive batteries while the batteries are still in the rack but I decided firmly against it). The only thing left to do with the power system is to connect the ESC to the drive battery leads and install the receiver for everything else to draw power from.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/12_zps68dc4433.jpg)
From last weekend's work, here is the beginnings of the reciever block which fits to two circular bulkheads which make up the servo compartment. The rectangular slot in the facing side is for the main power plug to sit neatly in.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/13_zps97610128.jpg)
Here are the two sections of the plug which fits in the aforementioned piece. The plug on the left goes to the main and receiver batteries and there is no heat shrink on the strain relief circuit board (the board makes it much easier to solder connections to than the pins on the plug itself). As it turned out there space inside that small compartment was at such a premium heat shrink would have become a hindrance on the left section.
On the right is the part of the plug which feeds power to the rest of the boat. The two large wires supply the ESC while the smaller cables are running in parallel off of the receiver battery. One set goes to the receiver and another to the piston control board.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/11_zpsb35b02b7.jpg)
Here is a close up of the piston control end as it stood last week. Most of the work is complete- the white microswitches have been connected to the motors and the circuit board and you can also see the small cuboid magnets on the large gear. The Hall Sensor is the red bar mounted close to the magnets (visible here just above and running parallel to one of the brass support rods). The only connections missing is the cable from the pressure switch which plugs into a two pin connector visible at the top and on the reverse side of the board and the main power to the unit which is provided through the small blue block labelled with black and red paint.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/14_zps90c283fa.jpg)
As the tech rack stands currently with leads of the batteries installed and the servo/esc/receiver block installed aft of the piston tank. the three black wires from the ESC on the left plug into the motor and need little to no further work, but the battery leads need hardwiring to the supply cables from the main battery. The receiver will be mounted on the grey plastic plate facing the viewer into which all four channels will be installed along with the power lead from the receiver battery, which you can see as the only Red/Black coloured servo lead in the picture.
You can also see the servos mounted sideways in the boat just forwards of the ESC.
It's starting to look like a proper tech rack now and will soon hopefully be ready for it's first power up and calibration of the main systems.
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Looking great. You want to use a multimeter to check that current can't flow between adjacent contacts of the MPX connector. I fried my first one, turned out the flux i used to make it easier to solder was a conductor and bridged some of the contacts. It was only a tiny current that could pass but it managed to melt the connector after a while.
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Looking great. You want to use a multimeter to check that current can't flow between adjacent contacts of the MPX connector. I fried my first one, turned out the flux i used to make it easier to solder was a conductor and bridged some of the contacts. It was only a tiny current that could pass but it managed to melt the connector after a while.
That's a very good idea. I checked while I was constructing it and there were no issues, but I went back and double checked and yes there is a slight short circuit on the male plug between the reciver power leads. It shouldn't be too much trouble to correct it and putit back together.
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As it turned out, the 'short circuit' was actually the resistance across the piston control circuit- there weren't actually any faults with my dodgy wiring.
Still, now with the ESC power cables soldered together and all the power systems in place, I installed my 40MHz receiver as per instructions (though the aerial will likely be modified later for use in salt water) and got ready to do all of the calibration and set up of the electronics.
As is the custom, I built an ad-hoc shrine around the 'test rig' to the machine god to bring me good fortune.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/15_zps8c496c08.jpg)
Well, I guess it sort of worked? The ESC worked fine, although the power leads as marked in the manual were the wrong way around (the water cooling ports were also missing so it could have been a slightly different model of ESC). I also set up the autolevel which works now and I *think* I've successfully set the servos to 60% throw, but I'll only know for sure once the whole lot is connected up to the control planes.
Setting up the piston tank though is a can of worms. It seems to go through the setup of the proportional unit all right until the end then the red light of low voltage doom comes on. Since I don't have a proportional slider for the dive unit yet I then switched it into non proportional mode and the tank just sits there with the red low voltage LED on (after turning everything off and on again). According to my voltmeter the receiver battery was still running at nominal voltage so I'm not entirely sure where the problem lies. My voltmeter might be lying though so I've put the receiver battery on charge to see if that solves the problem. If it doesn't I might have to muck around with the voltage cutoff potentiometer which I REALLY don't want to have to do.
The piston does automatically move to 'empty' then the power is first switched on though which is good.
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And a very, very quick update- I think I've found the cause of the problem. I've only just found the wiring diagram for the whole sub (I have no idea where that piece of paper's been lurking, I didn't know it existed until an hour ago) and it turns out the ballast tank should run from the 12v drive battery, not the 4.8v receiver pack.
The instructions as written in the step by step guide I somehow interpreted as needing receiver power to the ballast tank, whereas in fact the one step was referring to two entirely different things, probably because it made the logical assumption whoever was building the thing would have noticed the separate wiring diagram!
I short, I am one of the world's biggest idiots for not going over the paperwork more carefully before starting!
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Jack....you certainly are not JC on the cross with misinterpreted black magic >>:-( instructions :embarrassed:........keep us posted :-)) ..... Derek
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What radio are you using, Jack?
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The piston tank is now commissioned in non proportional mode. I re wired the plug, made sure the auto-bail function worked, plugged in the reciever battery and... nothing. Then after unplugging the reciever battery and inserting it the correct way around (it's the first battery of that kind I've used where the male has no guide rail, it will take some getting used to) and it works as intended.
Next up is sorting out the propshaft then sorting out the rudder linkages and connecting the tech rack to the hull. Not really a whole lot left before it will hit the bath (I hope!).
What radio are you using, Jack?
At the moment I'm using a 40mhz Futaba 6EX-PCM. I haven't popped the hood yet to see if a proportional control can be fitted to channel five or six. If not then I will be most likely buying another transmitter with a proportional slider option fairly soon- managing the piston on the same stick as the throttle I can see becoming tiresome, fast.
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Hi Jack.
if you make a good job of the build it can make silly money in germany.
http://www.ebay.co.uk/itm/281521952930?_trksid=p2060778.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.co.uk/itm/281521952930?_trksid=p2060778.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT)
frank
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Hi Jack.
if you make a good job of the build it can make silly money in germany.
http://www.ebay.co.uk/itm/281521952930?_trksid=p2060778.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.co.uk/itm/281521952930?_trksid=p2060778.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT)
frank
If you read the ad properly you can see that's not the engel. It's twice as long and more than three times as heavy!
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Not many digital sets can be reconfigured by exchanging switches for pots. The FC16 is pretty good in that all 8-channels can be configured as switches or proportional channels, and it's still available new and not too pricey.
If you don't mind searching around for a 40mhz module, a Turnigy 9XR (or a 9XR pro) is extremely versatile and they cost peanuts. A FrSky Taranis is really flexible but about three times the price, still very good value though.
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Didn't realise you could put a 40mhz modual in a 9x, that's very good to know!
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You would need to make some mods for the aerial. Another alternative is to look at the higher frequency modules.
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I have to admit I am tempted by the F-16's, they do look very good.
I don't have any experience modifying transmitters (just like I have no experience with submarines!) so I'd need a fair bit of help both sourcing a module for converting a 2.4Ghz and then installing it.
One of the next steps in construction is installation of ballast, for which it reccommends using decent fibre reinforced tape. I'm hoping that kind of stuff is available in hardware or home improvement shops. I'd like to follow the instructions and reccommendations by the manufacturer as closely as possible during this build.
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Fibre reinforced tape- duct tape fits the bill.
If you're not confident tinkering about inside a transmitter, then your best bet is to source either a decent secondhand 40mhz transmitter, or get a new unit.
A synthesized set is the preferred option, but there isn't a whole heap of choice, and they tend to be upper end transmitters. An exception being the Multiplex Cockpit SX, if you can find one.
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I've started working on the hull of the boat now, things are really starting to come together- it might even float soon!
I've added the main ballast weight into the hull. In the manual it said to do this after putting in the rudder linkages, motor, etc but I believe that it would make an already tricky job harder while putting in the linkages and motor won't really suffer from the very slightly reduced room.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/16_zpsa7440188.jpg)
The first strip in the forward section. Note the two brass pins as guides- this section must be 1mm off centre and those pins are it's guide rail, so to speak. Really very useful!
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/17_zps165ba52a.jpg)
The second strip- this is where things have gone a touch wonky. The two pieces are supposed to be perfectly parallel and as close to the sealing ring as possible. They're out of alignment by a few degrees and are about 2-3mm back from the locking ring, which could cause some trim issues. Given that the opening here is just about big enough to accept my hand, it is much harder than it looks to get everything lined up- this took three or four tries.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/18_zpse249d0c2.jpg)
The stern ballast- now this I'm MUCH happier with. It's as it should be more or less exactly. But, given that I can hold the back end while putting it in it is far, far easier than the bow.
Next up, the push rods for the rudders and the prop shaft!
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I have to admit I am tempted by the F-16's, they do look very good.
I don't have any experience modifying transmitters (just like I have no experience with submarines!) so I'd need a fair bit of help both sourcing a module for converting a 2.4Ghz and then installing it.
One I did earlier, works perfect, switchable between 40Mhz and 2.4GHz. Never use it as I moved to more exotic gear.
(http://i136.photobucket.com/albums/q191/Wheelerdealers/118522d1_zps4eb4025c.jpg)
(http://i136.photobucket.com/albums/q191/Wheelerdealers/1c6288e1.jpg)
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Well, last night the sub was ready for bath testing, but somehow overnight the O ring has developed the ability to leak air like nobody's business no matter how much its' cleaned or has sillicone lubricant applied.
Add to that the fact that after putting in the batteries there is woefully inadequate room for battery connectors you have the problem of said connecting block coming out and rubbing on the side of the hull, which causes the dual headaches of scraping the lovely yellow paint off of the lead ballast into great big chips which then get adhered firmly to the lube on the O ring AND breaks the battery compartment into it's respective bits trying to get the tech rack out.
It's the latest in a string of minor issues that have been popping up over the last few days which have been driving me to distraction. I actually had hoped this sub being small and easy to manage I'd be able to sail it often but if it keeps throwing wobblers like this it isn't going to happen.
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Jack,
Take a breather. Rarely does everything go smoothly. I adopted the mindset knowing it will get frustrating and at times I had to walk away or there would have been more parts than original because I smashed things.
Not having built your sub or know which o ring is giving you problems, but on some of my subs, I had to wrap Teflon tape two or more times in the channel the o-ring goes in. This in effect pushes the o-ring out to fit tighter against the tube. If it is a shaft o-ring, it might need replacing. Although tolerances are good, I cannot imagine that it is perfect or that there might not be a nick or damage on the o-ring. Anyways, stuff happens and if it gets to you, take a break. You are doing great on this build.
Peace,
Tom
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Are you sure the leak is on the main hull seal, and not one of the other smaller seals?
You shouldn't need to break out the Teflon tape.
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I've omitted a lot of the photos and details of the build since last time. I've put everything in the stern section together and immersed it in the bath prop down. There wasn't any leakage around the propshaft, rudder linkages or air/water lines. When put together and testing out of water air can be heard escaping around the bayonet lock holding the two sections of the boat together.
I have decided to leave it for a couple of days but I will add the other construction details later.
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That's surprising given that these parts are generally accurately made on Engel kits. I would use the old gas fitters trick of pressurizing the inside and brush some soapy water around the suspect areas, that will pinpoint the leak very quickly.
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One part to pay attention to (given this was glued in the factory) is the inner part of the hull where the bayonet lock is glued to the hull. I found it was easy to get a little void.
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I've just tested this with the soapy water technique and it confirmed a leakage around the bayonet lock. But it was inconclusive as to whether where was air leaking from the stern bulkhead so I filled up the bath, filled the ballast tank out of the water to increase the air pressure in the sub and immersed it. Tilting it every way I could I couldn't see any bubbles in the wet stern compartment (with the auto pitch control on the servos were wiggling about a fair bit to testthe bellows).
However, as I thought there is a constant stream of small bubbles coming from the bayonet ring, specifically in one place- on the port side where the 'hump' would meet the main cylindrical part of the hull.
Before doing the test I cleaned off the O ring of dust and grime as much as possible and the lock on the inside too then gave the whole thing a generous coat of universal silicone lubricant- less thick and sticky as the kind which came with the sub but easy to acquire and apply in liberal quantities, potentially before each sailing.
Tomorrow I'm going to take the O ring off completely for an absolutely thorough clean and inspection then try the bath test again. If it still leaks then it's probably as Mankster suggested and there's a void in the bow bayonet lock- while the hull was pressure tested before sale I've found it requires a generous application of force to initially separate the two parts of the boat so the factory seal may have given up under stress.
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You really shouldn't need much if any grease. I put a tiny smear on the seal just to reduce the friction, but it's the rubber that does the work. If you're having to ladle it on, then it's a sign there's a problem elsewhere.
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You really shouldn't need much if any grease. I put a tiny smear on the seal just to reduce the friction, but it's the rubber that does the work. If you're having to ladle it on, then it's a sign there's a problem elsewhere.
A problem elsewhere is the most likely issue. I'm glad you don't need a lot of grease- that would rapidly turn into a nightmare.
If the bond to the hull with the plastic part of the bayonet has got a void in it how would you reccommend sealing it? I'm thinking of using some silicone sealant if it isn't a big gap but I'm not sure if that would be a good idea.
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Epoxy, Stablit or Devcon Plastic Welder. Silicone has its uses, just not to waterproof a sub. I would locate the hole if possible and dig it out with a burr in a hobby drill before re-sealing the problem area.
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I was thinking may be Deluxe materials Fusion. Set's up very strong, and totally waterproof, but it's runny when mixed so it seeps into gaps better than some other acrylic or epoxy glues.
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Unfortunately I only just checked back here after Subculture made the last post and I've already done done some work here.
I've taken the O-ring out and thoroughly cleaned the mounting- there was a lot of 'gunk' for want of a better description, mostly fibrous trapped under or around the O ring which could have been causing the issue. I inspected the O-ring itself after cleaning and I can't find any damage, only very slight irregularities on the surface around the inner and outer edges probably as a result of moulding but nothing major.
I've started putting epoxy in the bow just in front of the bayonet lock to seal it. A big thanks has to go to whoever told me how epoxy works when hot (probably Unbuiltnautilus)- after carefully applying to the area and pushing it into the gap as much as possible with a spatula without getting any on the inner surface of the bayonet lock (which would cause serious drama!) I heated it up with a hairdrier. The epoxy went very, very runny very quickly, so I could actually move it around about half of the ring and it seems to have left a veneer behind and hopefully havs seeped into cracks. I let most of it pool where I noticed the leakage and it set hard in under five minutes.
I'm going to let it set for a few hours and repeat the process on the other side of the sub before testing the seal again.
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Jack....must agree with UBN here....Dow Corning Silicone type material may have uses if scientifically placed in a clean room environment with equally clean mating parts which were also designed for such adhesion
However the above I suggest precludes it for any general use of Silicone GOOP <*< in the modelling or home repair water proofing arena
O-ring's were designed to be a pressure energised seal element........they also necessarily rely on correctly dimensioned cavities, [compression] clearances & surface finishes to effect fluid tightness
One of the difficult things here is that both British & Australian Standards for o-ring cavities are based on a pressure application....[~~~200 Bar]...so are not necessarily suitable for static conditions of say 1 Bar or atmospheric conditions
I also agree that an epoxy sealant is the better plan for your rectification work, however maintaining the manufactures cleanliness of the surfaces to be joined is of paramount importance......Derek
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Most problems with sealing o-rings on subs stem from either sealing against a surface like the Himalayas or dirt contamination.
I find 10% compression is about right if both pieces are machined or known to be concentric, and move up to about 15% if the sealing surface is bit indifferent e.g. when sealing against internal bore of extruded plastic tubing which is often quite wavy.
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Well, I'm pretty sure I solved the dirt problem and to be sure sealed the inner join to the hull with epoxy, but it's still leaking in the same place, in fact it's actually gotten worse (beforehand the periscopes would at least retract and it would take a while for the air to leak out). The seal seems pretty tight, it takes a lot of effort to get it together and apart. I'm pretty much all out of ideas now.I could try the teflon tape idea but since it's already a tight fit I'm not sure if that's the solution either.
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Well, it's been a while since I last posted and a bit has been done in the meantime, although it still hasn't hit the water yet (I've been very busy with work). I also made an absolutely fatal error in the build which I will share here in case anyone else comes across the same situation.
Where I left off with the pictures was just after putting the pre sealed ballast in the hull. After this the stern section starts having its equipment fitted. It starts off with the bellows which will take the brass rods for the tail planes.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/19_zps505e55e9.jpg)
This was actually a remarkably fiddly job with a pair of long nosed pliers trying to get the bellows which are deeper attached. There's less room to work within that access hatch than you might think.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/20_zps1bd21e9e.jpg)
Now here are the pushrods and the main drive battery, which is two 6v batteries linked in series to make one 12v unit. It's done this way to save space in what is a relatively small hull. The instruction manual says that the threaded rod ends should either be soldered or superglued. Here you can see that they have been soldered, but later one linkage did break so I then superglued it and it seems to be a good bond now. These rods are then passed through the bellows to be linked to the X-rudder linkages, which have been pre assembled.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/21_zps147bb02c.jpg)
Here are the pushrods in their final positions. Note that the rod closest to the hatch is bent- this is to stop the pushrod from flexing when the rudder is moved, which puts pressure on the bellows and can cause the rod to seize in place. Judging the angle is difficult, especially since the bend must be done in situ, as it will be very difficult if not impossible to feed the rod in from the stern section (or was when I tried).
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/22_zpse558e187.jpg)
Here's the dry side of the aft bulkhead after installation of the servo pushrods. Note that the clips put on the threaded end caps are out of focus.
Now this next step is where things went badly wrong, installing the propshaft. I followed the instruction book to the letter as was recommended and so I missed a key step which came back to haunt me later. To prevent confusion, I'm going to put the next photos in the order in which you SHOULD install this thing, not how I DID the first time. The error I made was very simple and anyone with a little more experience probably wouldn't have made it, I'm pretty sure.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/30_zpsdndnm2rx.jpg)
Here you have the propshaft assembled but everything isn't quite put together. The coupling is very simple, just a piece of brass machined through with four grubscrew slots. Given the tech rack and stern bulkhead's precise machining, there shouldn't be any mis alignment of the motor and propshaft. Note you have to put the motor mounting plate on before linking the motor to the shaft, because that mounting plate is also where the shaft leaves the watertight compartment and has a rubber seal- if you push the threaded end of the shaft through, you will destroy the rubber seal and your boat will leak, a lot. Luckily the shaft is long enough that this plate doesn't get in the way when you're joining the shaft to the motor.
NOTE: the prop and spinner are attached in this photo. In the instructions, the prop is attached after the shaft is installed and here it will need to be removed to fit into the submarine. However, I strongly recommend at this stage putting the prop on and giving the prop in one hand and the motor in another a firm tug. This ensures that your motor and propshaft linkage are on properly and the shaft won't come out if you go into reverse.
It is important to do this check at this stage, because the brass linkage will fit snugly into the mounting plate and will be totally inaccessible without completely taking the stern to pieces if you do have a problem. I can't stress enough how much of a total pain that is. In my case I followed the instructions and essentially completed the entire sub. Then I had leak issues, which made me take the submarine to the clubhouse, where it emerged that my leak problems were caused by having too much silicone grease on the O-ring and it managed to go into the water, dive and emerge just as it's supposed to. Then I put it into reverse and the propshaft came loose. After taking the entire thing apart and putting it back together, lo and behold it's leaking again, caused by something I did taking it apart. If I'd tested the prop linkage at that much earlier point this sub would most likely have been sailing happily for a while (or something else might have come up, who knows).
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/23_zps6f2d8baa.jpg)
Here's the propshaft with the motor mounting plate on and greased. Note how the motor and propshaft linkage is now inaccessible. the green grease is also pretty cool- when it's no longer visible on inspection it is time to grease again.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/24_zpsa732c17c.jpg)
Now the motor is mounted, plugging the largest hull in the stern watertight bulkhead. I HIGHLY recommend a nut driver for this step, if you don't have one it is impossible to do by hand due to the depth and restrictive size of the compartment. I first put these nuts on with pliers and it took over an hour. With a good driver, it takes five minutes.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/25_zpsc2380703.jpg)
The wet half of the propshaft. Note how most of the rotating part of the propshaft is entirely exposed to the water. It probably cuts down grief with keeping it greased but I can't help but wonder what the hydrodynamics are like inside that wet compartment when it's going.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/26_zps3423892b.jpg)
Next is installing the servos into the tech rack. Due to limited room and the fact you use the third hole from the centre, the end of the servo arm has to be cut off. Since there are two, here is a picture between an original arm and one I prepared earlier(tm). The servos then literally snap into place in the tech rack.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/27_zps4dffad3a.jpg)
Here's the watertight stern bulkhead with everything bar the tech rack support bars attached. The large pipe takes water in for the ballast tank. I found handy advice to run it under hot water immediately before installation to soften the end of the pipe, which makes it easier to slot over the brass collar by orders of magnitude. Again, due to depth and narrowness of the compartment you need to use pliers to do this which isn't the easiest thing in the world. The smaller tube routs to the pressure switch, which will hopefully return the sub to the surface if the model goes below 3m of depth, which runs the risk of pressure and other, more sinister unknowns killing the model and making it irretrievable under its' own power. This smaller lead is easier to install, but with pliers you do have to be wary of ripping it if you aren't gentle.
At this point the tech rack is joined to the stern section. Here a lot of things need to be done simultaneously- the ESC must be linked to the motor (which given the positions of the two bits of kit and the length of cable provided means the pliers come out again and you have to be very careful. I also found that the bullet connectors didn't have quite enough rubber coat to completely cover the connection, leaving a small golden strip visible so I wrapped each connection with electrical tape to prevent any unlikely short circuits (as said earlier, you want to disassemble the stern as infrequently as possible so mitigating issues before they arise is essential). The piping is connected to the routing in the tech rack and then finally the pushrods are connected to the servos. This is done last because the reach of the arms only gets to the final position of the servos, so the tech rack has to be physically bolted on for it to work.
There wasn't a lot of point trying to take photos of these steps because they're all pretty straightforward, even for a build as simple as this and given their nature getting photos of this work would be tricky.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/28_zps397f87f2.jpg)
With everything installed, this is what the sub looks like from the outside. Which is to say, identical to when I started! Picking the model up however there is now a very healthy weight to it which is immediately apparent.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/29_zpscaa2fa99.jpg)
Then the prop and spinner are screwed on and the dive planes are fitted. Take note, when the instructions say use only the tiniest drop of superglue, they mean it. Luckily, for most of these planes, the fit is tight enough that they can really go on without any glue at all, but if you do need to glue them as they're resin superglue will bond them to anything and in lightning time (something I somehow forgot from my many years of sci-fi modelling with resin). As a result, one of the tail fins (the lower starboard one) is about a millimetre further from the hull than it should be because it got momentarily stuck pushing it on and the superglue went off before I could push it in further. Every attempt to remove the fin have ended in failure so far and since it is only minor I probably won't try much more to fix it (unless there's a chemical I could use which doesn't harm plastic and resin but attacks superglue, in which case I might), for fear of damaging the submarine.
At this point you are ready to test the submarine. This is where I discovered the leaks, found the solution to the leaks, lost the propshaft, took everything apart, fixed the shaft, leaked again, took everything apart again thinking one of the water lines had come off (they hadn't), still leaking etc etc etc.
When I build up the will to go leak hunting again it will be time for trimming and I'll take photos of the trim weights and the completed tech rack et al.
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So, today has been a mixture of ups and downs.
I took apart the stern (again) on Sunday, discovered that the ballast feed had come loose, fixed it back in place and I installed the reciever for my shiny new MC-15 and got the Hall effect sensor put into action, then had a look at the tailplanes and servos and had a look to see if I could get them to change in all directions. In everything I was met with success. Here's how the tech rack looks.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/33_zpsurg4rbjs.jpg)
The power leads need neatening up at the bow but that's all that's visually going to really change on this tech rack now.
I decided to power it all up, seal it and check for leaks on Monday evening and to my surprise, it passed in air, so I filled the bath and tested it in the water. It seemed that there was a minor leak from the O-ring on the starboard side so I took it out, cleaned it up and it appeared not to leak any more.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/32_zpsc1ybwbfa.jpg)
Amazingly for surface running the model seems to sit right in the water and it does look good.
The sub then managed to dive and surface multiple times using the piston and I was ecstatic. You can see the video of it doing this here:
https://www.youtube.com/watch?v=tvqEhNBnMk0 (https://www.youtube.com/watch?v=tvqEhNBnMk0)
(the video is unlisted, so only people with the link can see it).
Unfortunately, the problems started literally flooding in. As you can see in the video, one pair of tailplanes has become totally unresponsive to anything and I have the sinking feeling that the servo has burned out. Also, after being prompted to do a motor test the prop screwed itself into the back of the hull as there is no gap between the threading and the hull. After gently putting the prop back in it's original position spinning up the prop makes a very unhealthy noise (which I hope against hope is just the linkage inside coming loose again). Also the sub is trimmed with the stock trim weights and is nose heavy, so some of the trim weight will need to be removed (though that particular issue is so far down my list I'm not really worried about that at all).
There also seems to be some pretty major interference which crops up from time to time, which is annoying (but since I get odd servo chatter even on all of my 2.4Gz models I'm rapidly coming to accept this as an annoying fact of life), most worryingly which sometimes prevents the piston tank from emptying (though the auto bail on signal loss system is still working).
After taking the model from the water, I discovered everything in the bilges was wet and an alarming amount of water came out, so the leak is still there, it just doesn't show very well on leak tests.
I'm now getting that horrible sinking seeling that I'm horribly out of my depth here.
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Looking at your pictures, and going by your description, you have a leak on one of the seals, but it's possibly being masked by all the grease you're slapping on. You only need a very small amount of grease just enough to relieve friction. Water works and I would try that for initial bench tests.
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I didn't know water could be used to help seal the O ring, that will be useful for the tests.
You are almost without a doubt right about too much grease. That caused the leaks last time. I'm going to tackle the issues that came up in the test one by one, starting with the drive and rudders since I might have to order in replacement parts.
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Water doesn't seal anything, it just reduces friction. Course it dries out, hence why grease is used. But use it sparingly, you are ladling it on!
Do a leak down test, pressurize the inside and see if it holds air, You can use the piston tank to pressurize the inside. Ensure the tank is empty before you button up, put the hull halves together and operate the tank to full, that should put a one or two pounds of pressure inside, and leave it overnight. if it doesn't hold this pressure, then you're no good for diving.
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That process is, more or less, detailed in the manual to check for leaks, though it only reccommends doing it in air for a couple of minutes, (possibly because of the piston's automatic safety features which could cut in) then transferring it to the water after pressurising the inside and checking for bubbles. I'll see if I can get it pressurised for at least half an hour in the air before trying it in the water though.
I think at the moment I'll be focusing on the mechanical issues and sorting the seal last because it's likely I'll disrupt it, get dust on from prolonged periods of being open on the workbench, etc.
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Managed to fix the issues with the propshaft by using a very tight locking nut in conjunction to the plastic spinner to stop the prop over tightening itself when coming to a stop and the momentum of the prop wants to keep going. Unfortunately I have blown one of the servos. Taking them both off for testing on a seperate reciever one makes an awful buzzing of a stalling motor at anything but idle position. I took it apart to see if there was something jamming the gears but now the servo is completely dead, I've now ordered a new one.
I think the throw on the servos might have been too long so the servos were trying to push past the point they should have, encountered too much resistance and broke. I did follow the instructions to reduce the servo throw to the best of my ability and it seemed to work though, so the other possibility is that the bent metal push rod is at the wrong angle leading to a similar problem. I've ordered a new servo and other miscellaneous spares and I'll be completely disassembling the stern and rebuilding- probably with at least one other person checking especially with regard to the bent push rod.
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I've done some more work on the sub. I've started painting it now and trying my hand at airbrushing for the first time in a very long time! Fortunately it seems to be working better than the last time I tried it, where I killed the airbrush completely. Unfortunately there are still a lot of kinks to work out- the first go at masking off was a disaster with paint leaking everywhere, which will require a lot of work to fix. however the second set, the darker grey paint was a much better result.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/34_zpsqwzany29.jpg)
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/35_zpsczudoutt.jpg)
Still to do there is another dark brown a dark brown colour to go on, having taken my inspiration for this unhistorical scheme from some Swedish Navy patterns I've seen. My choice of acrylic paints is coming to haunt me though as masking tape on airbrushed layers is bringing up the paint in places even when left for over a day to set. On the other hand, it will be much easier to distress the paint below the waterline to get a nice fading away effect. The whole sub will also be given a generous coat of matt varnish to keep the paint scheme on when it is finished.
I do like the light grey on the submarine though, it brings out a lot of the hull details which the darker colour keeps hidden.
I'm also glad to report that the mechanical issues have been sorted. A long day in the workshop with Unbuiltnautilus and a lot of biscuits saw the dead servo replaced, the prop shaft assembled properly and last but by no means least the X rudders were trimmed and set up correctly so that not only is there decent throw in all directions, but also the servos aren't being overly stressed in any position (solving this took hours). The only water testing it got was the stern immersed in a bucket to check for leaks and then running the motor and ballast tank in water to check function. The results of running at full speed in reverse were impressive- it was like having a large water pump throwing water out of the test bucket.
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I've put the brown colour of the camouflage on now, using a mixture of airbrushing and regular painting using the thinned down paint. I've gone overboard with it I think- the brown should cover the second smallest amount of area after the very dark base colour. I think I'll be adding a lot more of the middle grey and covering over some of the brown to compensate. there's also a lot of 'touch up' work needed where paint has run or the masking take has lifted paint off. I'm wondering if there's an oily residue on the ase dark grey coat which I didn't manage to remove when I was preparing for painting which is causing the paint on top to lift. If that's the case I could have some real trouble in the future, but I'm not sure that it is.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/37_zps3jkez29u.jpg)
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/36_zpspey1llru.jpg)
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All dinks and dents help with the weathering :-)
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If you ever operate that in a swimming pool, it will completely disappear!
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Didn't manage to get a great deal done this weekend, but I have managed to put some more of the Mid grey on and cleaned up the damage from the masking tape- it's a spot the difference round! But I am happy with the camouflage, it's now moving on to gently teasing the bottom line with warm soapy water and a scouring pad to get it to gradually fade out (I hope!), which I should in theory get done this week, if work isn't too long and stressful.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/39_zps3djwfh8a.jpg)
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/38_zpsebn4gu0p.jpg)
If you ever operate that in a swimming pool, it will completely disappear!
It would certainly be interesting to see! Sadly I don't have any swimming pools big enough I'm allowed to operate it in at the moment. I do sometimes wonder if have made the right choice with the camouflage though. While it'll probably look interesting on the stand at shows (at home she'll have to be stored in half, like O ring subs should), she will only have about three inches above the water, all camouflaged to blend in with light reflecting off of the water, things could get interesting. The only subs I've really seen in operation with any regularity are the much larger 6-7ft type 7 U boats and they're hard enough to see sometimes.
I'm thinking of either painting the tops of the periscopes, snorkels etc some horrendously bright Day Glo colours to aid in visibility and hope it doesn't ruin the overall look of the model, or try and make some kind of attachment for the stern part of the sub akin to a long pole, probably with red and white striping. This could also be used to extend the aerial for diving in salt water- which could be useful since my home water is very salty indeed.
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Perhaps a simpler method would be to incorporate a strobing LED in the fin pointing through one of the openings in the top. That should show up well in any water, and won't use much juice.
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Perhaps a simpler method would be to incorporate a strobing LED in the fin pointing through one of the openings in the top. That should show up well in any water, and won't use much juice.
That's a brilliant idea! Positioned correctly you could have light coming out of the top and the windows for better visibility. The only issue is implementation- on the sail you can't have any penetration into the WTC as there's absolutely no room between the hull and the tech rack. There is a lot of space under the 'hump' which is removable on the front section to use. It would be a case of making sure the weight doesn't cause top heavy issues and waterproofing the entire circuit, which could be a bit of a pain.
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A couple of brass bolts through the rear endcap, fed off the receiver bus. Then solder some flyleads up to the LED, which won't weigh very much at all.
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Or even simpler, use two of the pushrods as your conductors
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If I ran it off the sub's internal power I'd have to put the light on the tail end rather than the sail, but it still has legs. Using the pushrods is a good idea, I'd just have to look into what effect the current could have long term- the pushrods are resistant to corrosion and in theory the back end of the sub shouldn't have to be dismantled for a long, long time.
I was thinking of mounting a small round lithium battery under the hump with a very simple swtich- it should last for a very long time without needing to be replaced.
I've actaully just found a small bicycle rear light (it's amazing what you find lying around) which has two very bright red LEDs and a simple push button to make it work, powered by some lithium batteries. It would take very little work to chop the LEDs, extend them and seal the rest of the unit in the 'hump'. It would only weight a few grams and looks like it wouldn't create any more air spaces.
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I tested the sub in the bath last night and it worked perfectly. Took it to a display today and while it got some attention on the bench I really wanted to test it in the small pond we had. I ran into a lot of issues with the O ring, despite it having worked great yesterday. I cleaned it thoroughly to get rid of any grease, dust, water etc and it didn't actually work, it kept leaking when the hull was unpressurised to force air out of leaks. I then wetted the O ring with some water and by some miracle it sealed properly. Turns out the 212 is an utter pig to turn when it's on the surface with half of the x tail out of the water, but once it's down it turns much better and also becomes much, much faster when it is under water due to the hull shape.
She's also very bow heavy and needs the weight there reducing quite significantly.
It was a gloriously sunny day and the pool small, so the air inside the sub heated fast and tripped the pressure sensor within five minutes. I reset it successfully once, but it glitched the second time and I foolishly decided to turn the sub off and on again. It worked, but involved opening the seal which then refused to set.
It is one problem area on the lower third of the port side. Feeling around it on the outer edge of the area the O ring should sit there is a slight machining defect, but it shouldn't protrude into the area where the O ring sits when it's locked. I'm thinking of putting the thin film of Vaseline over the ring, since the water did seem to help it set.
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Using a grease or some other substance to effect a good seal isn't the way to go with an o-ring fitting.
A small amount of grease helps reduce friction when pushing the two halves closed, but that should be its only function.
Engel use a moulded fitting on this boat, so I would inspect that very carefully, and also check the o-ring for any nicks or damage.
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I'll check the fitting before putting any grease on, it's a very good idea to go over every part in the join carefully. I'm not sure it's the O ring itself because I removed it and cleaned it and it's leaking in the same place despite moving the ring around, although it's still worth checking. If it is the bayonet it would be a pain.
It is encouraging though that it does sometimes make a perfect seal, so whatever is there is probably very minor (which worryingly, also reduces my chances of finding it).
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Will if you get really stuck and it turns out to be the fitting, bear in mind that you can get different thicknesses of o-rings e.g. if it uses a 3mm o-ring, you cfould look at aan imperial size of 1/8", which would be 3.175mm. That would give you a bit more squish. You could perhaps use a silicone o-ring which tend to be a bit softer than nitrile.
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I took the submarine to Sumner's Ponds Model Show on the weekend- the same show where I had a play with another 212 last year. Those people were there again and took a look at the bayonet ring. The fitting itself is OK, the O ring might also be fine but could be drying out, so very lightly greasing it with a marine grease could help.
Unfortunately, sometime between Netley and Sumner's Ponds (6-20th of June!), the hose running from the wet bulkhead to the brass tube for the ballast tank gave up and ruptured at one end. Luckily it didn't do it in the water.
Despite heroic efforts and the generous donation of more hose on Sunday, she didn't sail- the replacement tubing is 1mm thicker than the original. Whilst this makes fitting it much easier (although it'll want a cable tie collar for security), the precision cut nature of the tech rack meant that shoreside installation was impossible. However, five minutes with a rat tail file should remedy the issue.
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Blimey you if you didn't have bad luck you'd have no luck! Hats off to you for sticking with her, hopefully the end product goes as well as she looks!
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Well, after something of a break in building (partially caused by me starting to work six days a week, one of them unpaid- I wonder if I'm sane sometimes) I've ordered myself a magnetic switch- I figure if I'm going to be messing around with the back end to fit the new ballast lead I might as well put the switch in as well. In addition to actual grease (Lewmar was reccommended), this should help a lot- once it's nice and watertight at home in the bath, I can turn it off without breaking it down, then if luck holds it would be fine at the pond the following day. Also if it runs into a computer glitch which needs resetting, again no need to disturb the seals.
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The magnetic switch has been wired up and tested. It works pretty well, although I've noticed that near other relatively highly powered electronic devices (such as my soldering iron), it doesn't work and merely causes a lot of servo chatter when the magnet is passed by the switch, which is something to bear in mind (also in this situation it threw off a ton of radio interference that really messed with my radio across the room, although this didn't occur with the soldering iron off). It's most likely due to the interaction of the magnet with the fields generated by the coils in the iron when it's on.
Wiring is very easy, with pinch based connectors for the unit which is very convenient. I did have to extend the battery leads from both the main power and the Rx though to reach the unit's final position aft. The biggest issue is mounting to the hull. Because of the O ring and bayonet lock, installation on the forward hull is completely out of the question, which leaves the small aft part of the WTC which is rapidly becoming very full of equipment. The only place I could fit it was near the waterline on the starboard side with the entire circuit board laying against the hull because with the detectors sitting flush to the hull there was no way to prevent contact with the outrunner. Luckily it seems there should be enough range on the switch for it to work like this.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/40_zpspwcziihe.jpg)
Above is the magnet switch wired up. The rx switch module is to the left, overlapping the orange brushless reverse detection unit.
There will be final checks to make sure the switch works in it's intended position, then it will be fixed in place in the hull. Following this will be installation of the new ballast leads and proper greasing of the O-ring and with luck, she should be almost ready to sail.
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Hey Jack, I'm slightly curious as to why a magnetic switch was required? On my lafayette the great thing was that you only had to twist and pull the tech rack and you had easy switch access (unlike my typhoon which has many many bolts to undo). If it's a struggle to fit it or causing issues
It could probably be dispensed with. I am seriously considering a 212 so any feedback on this would be great!
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Ask yourself which is easier, opening and closing a hull, or swiping a magnet across?
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Hey Jack, I'm slightly curious as to why a magnetic switch was required? On my Lafayette the great thing was that you only had to twist and pull the tech rack and you had easy switch access (unlike my typhoon which has many many bolts to undo). If it's a struggle to fit it or causing issues
It could probably be dispensed with. I am seriously considering a 212 so any feedback on this would be great!
It's a matter of preference. If you find that you don't get dust etc ruining your O ring by the pond then it probably isn't very important, but in my experience with this boat and seeing a couple of others they can be a little temperamental, so a magnet switch will allow me to find problems at home where I can control the environment and not need to expose it to anything by the water.
The second point refers to the 212 itself. The pressure sensor inside, while very useful can be an utter pain on the 212. As soon as you seal her up the temperature inside the sub starts to rise from the sun having its' energy absorbed by the dark paint on the hull. This causes the pressure inside the boat to rise which will eventually trick the sensor into thinking she is flooding and blow the ballast then disable the piston. On a warm day this process can take well under five minutes. To reset it you need to equalise the pressure using the breather tube. Normally this works, but from time to time the computer doesn't want to play and the whole system needs to be reset. In this case it's FAR easier to swipe the magnet a couple of times and carry on sailing than faff around taking it apart, resetting it and then going through all the pressure checks again.
On the Lafayette and the Typhoon the internal air space is much greater and it takes a much longer time to heat up (the relationship of volume to time is likely exponential).
Engel is advertising a new Akula model in the catalogue they ship with parts which appears very similar to the 212 I purchased, using a bayonet lock and having the hull pre assembled and painted. also she will be a very similar size, so that model will also likely be susceptible to overheating, unlike the much larger older model.
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I think I'd dispense with the pressure sensor.
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I think I'd dispense with the pressure sensor.
I might well do after a while. There are only a couple of places I'd run her where the water is deep enough to trip the sensor and in most cases I'd lose signal and the tanks would empty anyway.
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A relatively quick update.
I've installed the magnet switch in the stern and it works beautifully, it will allow me to test the seals in a clean environment and then turn the submarine off taking it to the pond, which limits the chances of dust getting in or something else which could cause the O ring to leak.
I've also tested the O ring again and the perpetual leaks were caused by using the wrong or too much lubricant. Perfectly dry the O ring works, but after being immersed and broken again, with water on the ring it will leak. I've found that E-45 hand cream actually helps it seal magnificently, although I have today ordered some silicone and sticky grease from Engel which are what they recommend using (alongside a much needed stand!).
The test tank trials did show some water getting in without any leaks apparent, but it could be the way I'm taking the sub apart after being in the water, it warrants further investigation. Hopefully the maiden voyage on the lake will be soon.
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I think I'd dispense with the pressure sensor.
Agree with Subculture neither my Lafayette , Typhoon or Nautilus have the pressure sensor connected.
regards Mark.
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At the moment I'll keep the pressure sensor in. When I've run the sub a fair number of times and I'm confident she won't start to flood unexpectedly I'll probably remove the sensor because tripping every few minutes will be a pain. For the time being though I like the added security it gives. I'm also wondering if there's some way to keep the depth sensor working while disabling internal sensors, although given it's in one unit I'll wager that it is unlikely.
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Well, a bit of an update. I and Unbuiltnautilus took a really good look at this tub over the course of a couple of weekends and found some interesting stuff. The leak in the O ring always comes from the same place, but if you fit the lock in any position other than the one it's supposed to (so the ends are out of line with each other) the seal doesn't leak at all. While rotating the tech rack to find the wrong position to lock in the O ring, the forward ballast feed got snagged on something and was tugged loose, resulting in a somewhat rapid stern first sinking in the test tank shortly after. Luckily being fresh water a very fast retrieval and thorough drying out ensured no damage.
Also, the O rings listed as direct replacements from Engel are too big- the outer diameter is probably the same, but the thickness of the ring is much less so it doesn't sit in the allotted groove on the locking ring. Perhaps since the transition from the kit to the pre assembled hull version the locking ring has changed slightly?
On the fore half of the locking ring, we found a groove next to one of the projecting guiding sections. You can see it as a slightly whiter line (trying to photo white on shiny white is HARD) in the middle of the photo here. This position roughly corresponds to where the trouble has always been and due to it's position in front of the guiding point and its' depth is unlikely to be damage from sliding the tech rack in and out and is likely a minor machining defect, which is a pain in the proverbial.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/42_zpsxo24x0dh.jpg)
Still, after something like four hours of trial and error, thorough cleaning of the entire assembly and sacrifices to the dark gods of chaos the O ring finally sealed and wasn't blowing bubbles in the test tank. So, I turned the sub off using the magnets and we rushed to the lake as soon as possible, hoping that whatever was holding the seal true wouldn't slip in the meantime.
With the sun slowly setting on a freezing day in late April, the 212 went into some proper water for the first time.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/100_2736_zpstgzawc4o.jpg)
She ran fairly well, but on the surface your speed is heavily restricted because above a relatively low RPM the prop starts frothing up the water and blowing bubbles which doesn't help at all. The boat also suffered from some pretty severe glitching issues not far from shore- likely because the aerial is situated inside the pressure hull (which is almost entirely submerged) fairly low down. My local lake is salt water, which is notoriously bad for radio signals.
This was expected, I was gauging how well the default antenna will do- I will be extending it out at the stern so it hooks to the back of the sail in a relatively realistic manner. Hopefully this will give excellent surface performance at least while looking good. The odd time where I managed to just about submerge, through dynamic diving in reverse of all things, this submarine goes FAST and will actually start to plane under the right circumstances. These only managed to last a handful of seconds due to signal loss and the fact that a planing X rudder is useless for steering!
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/100_2746_zpsbn6kdf6m.jpg)
The piston tank doesn't work very well in salt water and needs to partially dynamically dive, which isn't at all surprising. Unfortunately after dynamic diving signal loss was almost instant so she slowly rose to the surface before automatically blowing the tanks.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/100_2749_zps9i9l7kea.jpg)
Unbuiltnautilus was running his (much nicer looking) type 7 and we got a nice comparison of scale and look of the models in the water together. It's also an amusing look at how diesel electric submarines in the German navy progressed over seventy odd years.
(http://i883.photobucket.com/albums/ac31/hawkeye92_photos/212%20build/100_2758_zpsmerdymjz.jpg)
Finally a shot by the edge of the lake after a fairly successful maiden voyage. To my continuing surprise, the O ring held out throughout the run (at least an hour) and there was no water inside the sub whatsoever.
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It isn't the tank at fault. Salt water is denser than fresh water, so the boat can be quite a bit more buoyant. You need to take a couple of ounces of lead along with you to counter that.
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Haha, my late at night knackered wording didn't help there. I might try experimenting with some adjustable trim weights for fresh and salt water running, but honestly I don't expect to hold a signal much below periscope depth in Canoe Lake even with the antenna modifications and she will happily get to periscope depth as is so I'm tempted to leave it alone.
I'll have to see how the external antenna goes though- if it turns out I can get a signal to the bottom of the lake near the edge I'll certainly be re trimming for seawater. Just have to remember to take it out before I go somewhere like Chichester and end up donning my scuba gear to retrieve it :D
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Unless you can keep the aerial above water you can expect to lose the signal immediately when submerged in salt water. It's also very hard on exposed metal parts. I would seriously consider running a sacrificial anode if you run in salt water regularly.
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The anode isn't a bad idea at all. I know Engel advertise their stuff as being almost totally corrosion resistant but I get the feeling that the prop at the very least will suffer badly and it doesn't hurt to be covered any way.
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Jack.....back on 31 December 2014 we noted......
'O-ring's were designed to be a pressure energised seal element........they also necessarily rely on correctly dimensioned cavities, [compression] clearances & surface finishes to effect fluid tightness
One of the difficult things here is that both British & Australian Standards for o-ring cavities are based on a pressure application....[~~~200 Bar]...so are not necessarily suitable for static conditions of say 1 Bar or atmospheric conditions'
Now you believe the manufacturer is supplying an o-ring which is not the correct size....are you able to accurately measure the o-ring cavity dimension and nominate the corresponding bore dimension?..............we can look at these & back check nominate the best o-ring to suit the dimensions
Using a fluid based lubricant will assist in the guiding & hence compression of the o-ring during assembly, however too much lubricant should have little bearing in the water tight integrity of the joint......dry talcum powder can be used as an alternate
Mention was made of using an MVQ or silicone elastomer o-ring as being softer....according to universal Manufacturers Standards, MVQ elastomer is listed as 70 Shore hardness, along with NBR at 70 Shore........[although someone could substitute a common 90 Shore hardness NBR o-ring which are widely used because of the greater anti-extrusion properties]
The only downside with MVQ is that they are produced in far fewer size variants around that nominal size.....come back with the dimensions..................
Derek
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The replacement O-Ring was without a doubt very wrong in size, being more like 2mm cross section rather than the roughly 3mm cross section of the original. You could get your little finger under the O-Ring with the slack evident.
As far as the antenna is concerned, the plan is to use stainless braided cable used for fishing line, which has a plastic seal over it. This should prevent any earthing or corrosion issues. All that we will have to look at is the antenna connection point and the hook onto the back of the sail.