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Author Topic: Engel Type 212A Build Log  (Read 27137 times)

Jack D

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Re: Engel Type 212A Build Log
« Reply #50 on: March 10, 2015, 10:01:19 pm »

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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Jack D

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Re: Engel Type 212A Build Log
« Reply #51 on: May 10, 2015, 11:59:00 pm »

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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Jack D

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Re: Engel Type 212A Build Log
« Reply #52 on: May 27, 2015, 12:48:09 am »

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.





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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Jack D

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Re: Engel Type 212A Build Log
« Reply #53 on: May 28, 2015, 10:56:42 pm »

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.




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unbuiltnautilus

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Re: Engel Type 212A Build Log
« Reply #54 on: May 29, 2015, 09:24:44 am »

All dinks and dents help with the weathering :-)
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Subculture

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Re: Engel Type 212A Build Log
« Reply #55 on: May 29, 2015, 07:26:27 pm »

If you ever operate that in a swimming pool, it will completely disappear!

Jack D

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Re: Engel Type 212A Build Log
« Reply #56 on: May 31, 2015, 10:50:42 pm »

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.





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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Re: Engel Type 212A Build Log
« Reply #57 on: June 01, 2015, 09:45:56 am »

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.

Jack D

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Re: Engel Type 212A Build Log
« Reply #58 on: June 01, 2015, 09:35:50 pm »

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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Re: Engel Type 212A Build Log
« Reply #59 on: June 01, 2015, 09:44:23 pm »

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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Re: Engel Type 212A Build Log
« Reply #60 on: June 01, 2015, 09:45:48 pm »

Or even simpler, use two of the pushrods as your conductors

Jack D

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Re: Engel Type 212A Build Log
« Reply #61 on: June 01, 2015, 09:53:04 pm »

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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Jack D

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Re: Engel Type 212A Build Log
« Reply #62 on: June 06, 2015, 11:39:32 pm »

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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Re: Engel Type 212A Build Log
« Reply #63 on: June 07, 2015, 02:32:06 pm »

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.

Jack D

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Re: Engel Type 212A Build Log
« Reply #64 on: June 07, 2015, 05:35:03 pm »

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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Re: Engel Type 212A Build Log
« Reply #65 on: June 07, 2015, 07:28:03 pm »

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.

Jack D

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Re: Engel Type 212A Build Log
« Reply #66 on: June 23, 2015, 10:55:06 pm »

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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TomHugill

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Re: Engel Type 212A Build Log
« Reply #67 on: June 24, 2015, 12:49:01 am »

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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Jack D

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Re: Engel Type 212A Build Log
« Reply #68 on: August 24, 2015, 09:05:57 pm »

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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Jack D

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Re: Engel Type 212A Build Log
« Reply #69 on: September 01, 2015, 12:59:37 am »

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.


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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TomHugill

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Re: Engel Type 212A Build Log
« Reply #70 on: September 01, 2015, 07:12:06 am »

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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Subculture

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Re: Engel Type 212A Build Log
« Reply #71 on: September 01, 2015, 09:12:08 am »

Ask yourself which is easier, opening and closing a hull, or swiping a magnet across?

Jack D

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Re: Engel Type 212A Build Log
« Reply #72 on: September 01, 2015, 11:34:18 am »

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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Re: Engel Type 212A Build Log
« Reply #73 on: September 01, 2015, 11:49:47 am »

I think I'd dispense with the pressure sensor.

Jack D

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Re: Engel Type 212A Build Log
« Reply #74 on: September 01, 2015, 03:09:11 pm »

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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