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[sub john]

HI Tim
           Nice to see you yesterday but I'm sorry but Pauline said she has not got time doing your sub she has had  enough of doing mine i don't know how she has got the nerve to say she has done it. But on a serious note yes the sub is coming along, i fitted the speaker on pressure plate today that's all ready to connect up to MP3 sound units, it was a bit of a job making that 5 pin plug and socket water proof but it will make it alot easier to take the deck away from the sub when working on it. It won't be long now before i try it


           Have got all the radio link built for under voltage warning for when the batteries are low but what has slowed me down is the periscopes getting the radar to go up and down and turn but i tried it all the other day and it all works fine. Think its a good idea that i have made the conning tower so you can unscrew it off the deck.


                    All the best John

[abreese]

looks good,just wringing more channels from my f14,like the brass work!.
merry xmas alan b

[sub john]

HI Alan
      It is starting to take shape now it is supprizing how long it takes to do all the railings, just on at the moment trying to do the MP3 players for sound effects but at the moment i think it is getting to cold to go out and try the sub on the water
   
       You said you was trying to put extra channels on your F14 on my transmitter for the sub i have split one channel in to 12 on- off functions for selecting sound files on 1 of the MP3 players.


     Have a nice Christmas Alan all the best John

[timgarrod]

Update

[sub john]

Hi Tim
      Thanks for posting pictures it's nice to see the model nearly finished now, all the self levering and the depth control electronics seem to be working spot on. In one of the pictures you have posted the sub is sitting about half way up the periscope shears and sat there for 20 Min's until i emptied the tanks now i know it all works i will have to start on the weld lines on the hull and conning tower and then get it sprayed but it is to cold to start thinking about spraying any way i will soon be able to bring it over to Derby.
                    All the best John

[salmon]

Very exciting to see! Seems like in no time we will see her maiden voyage!

[Subculture]

It would be interesting to read some details on the new electronic board you devised to replace the Engel item.

[sub john]

HI Salmon
       Thanks for reply, i must confess it has been a long time in the build but it is the electronics that slows you down when you have to design it and then build it, but i must say i am impressed in how well it worked in the test tank. At one point i thought it was sat on the bottom but it wasn't it was just hovering in the water, and like you said it won't be long before it goes out on it's maiden voyage. But i keep working on more ideas to go into these subs what i will have to do is put up some pictures of all the mechanics that works the radar and periscopes which will go up and down to where you won't them to be they work the same as a digital proportional servo, what i did was mod a sail winch which got me a bit worried about all the weight under the deck at the back all the bits that connect to the deck are water proof sockets and plugs that i made which makes it easy to work on the deck away from the hull. All so made the conning tower removable of the deck which again makes things easy when you spray it
              All the best John

[sub john]

Hi Subculture
        Was not very impressed the way the TMAX control board worked, the idea of using relays for switching the tank forward and backwards leaves a bit to be desired to say the least but that is just my own thoughts. The control board that has gone in to the Engel  gato works the same as a proportional servo but this only works the last 20 percent of the fill of the tank the other 80 percent can be switched in or out where ever you won't it to be the same as a normal piston tank, but the last 20 percent of the tank on the back and the front tank work off a presetable depth that can be selected from the TX at what depth you won't it to hover  there is all so 2 levelers one operats the front and one works the back tank. I bet you are saying why two but there is a good reason for it one of the problems that comes it to this it if you just filled the front tank to 94 percent the back tank has to go to 94 percent as well but still has to work full proportional movement  but the back tank has no longer got to work under depth control from the depth sencor what works the front tank but still has to work under level control so the front tank keeps it at the depth you wont it to be and the back tank keeps hunting to keep it level, which it can move grams of water at a time just to keep it level. The two drive boards are using  pics to control the logic as you can understand you would not be-able to do this using relays they just would not last very long. The control boards for the tanks have got H bridge switching using fets which all so has dynamic braking. The boards could deliver 80 AMPS if need be but of course they don't pull any thing near that.


                 All the best John 

[salmon]

john,
Just a curious question, on my Gato and I have heard others see the same issue, when the sub is surfacing, there is a slight list as it is rising. Do you see that in your sub as it is going from submerged to fully surfaced?
Peace,
tom

[Subculture]

I never observed that happening in the couple of Engel Gato's I've seen working. I think that may be a factor in models that employ ballast systems with an exposed water surface when emptying the tank.

John, did you complimentary P and N Mosfets for the h-bridge or use all N-channel with a charge pump for the high side switching?

Also do the PIC's run a full PID loop, or you using some simpler to control the motor?

[sub john]

HI Salmon
              You asked about when the Engel Gato surfaces does it list to one side i can not say that i have seen any thing that i would be worried about, i think allot of this could be down to to much  top weight which would make it rock when surfacing plus on the Gato when fully surfaced there is a lot of deck out of the water which does not help plus if you are talking about the Revel Gatos the plastic deck from what i can remember is quite heavy which is not a good thing to have which would probably make it tilt to one side. I have seen people fitting foam to the inside of the hull to try to stop this, if you looked at the real sub it has got saddle tanks on the outside of the main hull this is to make it more stable when on the surface as they act as big floats on the side of the hull which would give you a more stable sub when on the surface and plus you can alter side trim as well.
           All the best John

[sub john]

HI Subculture
        The board for the tanks has got P and N channel fet's to work as the H bridge the circuit for the H bridge if you switch both sides on at the same time as you know the H bridge would blow but the way this work if you switch both on at the same time it would not do anything would just stay switched off.


        Why i stopped away from using high and low sided driver is if you don't switch the fets off and on at say a high enough frequency  then the charge pumps on the high sided drivers would not charge enough to drive the high sided gates on the fets. The board that i have done has got logic level fets on it and it would work any where from 6 to 24 volts can't see there being a problem the gates on the logic fets are protected against over volts on the gates i have tried to blow it up but it is still working. The circuit boards are all SMD components the fets don't even have heat sinks on them as they don't even get warm i must say I'm pleased with the end result as it does seem to work well.
                               All the best John

[salmon]

John,
I was not clear in my explanation. It is not a permanent list, it is a slight tip as it is surfacing. It will right itself immediately. I found an explanation for the quick list and uprighting in an engineer tutorial about the center of gravity as it changes between a sub and a boat.
Just curious if you see that in your larger scale.
Peace,
Tom

[sub john]

HI Tom
      You said that the sub just tilts as it surfaces and then rights itself like you said it can change about the center of gravity, but i think that some of it can be down to the sub having to much top weight around the conning tower and the keel weight not being low enough. Even if you look at the big sub of mine when the sub has dived and then has  surfaced  with all the water that is under the deck and on top of the deck and on the conning tower the sub always sits lower in the water until all the water has drained off, I'm sure you have noticed this your self which again it does play a part in the sub tilting when surfacing. I can not say that i have ever seen the big sub tilt to one side as it surfaces and i can not say that i have seen it on the Engel Gato.


       Have been on the last week doing the weld lines on the hull and the deck sides and  on conning tower have finished doing it all but now have got to start sanding it down and start to think about spraying but the weather is a bit to cooled to think about that.
                         
                                All the best Sub John

[salmon]

John,
Good to hear from you and that you gave consideration to my ramblings.
Here is a youtube showing my sub running in one of its shakedowns and at about 1:48 into the video as the pumps are bringing up the sub, you may see the slight tilt happen.


[size=78%]https://www.youtube.com/watch?v=fR_Zh16zExY[/size]


I agree that more/lower weight in the keel can offset this, however with a 1/72 scale, there is not enough room for more for more foam to offset the extra weight. That transition does have a lot happening including the surface tension holding on to the deck as it exits the water.


Look forward to your detailing and more photos!


Peace,
Tom

[Subculture]

If you could increase the metacentric height on the boat, it would make the boat less agile underwater. So it's a compromise.

You have a large tank in that boat, as it empties you then have a large movable weight in the form of an exposed water surface, a bit of chop in the water or a slight breeze is all that is required to momentarily push the boat one way or another, and the water shifts in the tank and accentuates the tilt. Once the tank is empty or very nearly so, the shifting weight is gone, and the boat then stable.

This will happen in any boat, however in a boat with a very small tank in relation to overall displacement, the weight shift is much smaller, and thus so is the influence on the boats trim. In a nutshell it's unlikely to bother the owner/operator.

If you have a system with a constantly shifting baffle e.g. piston tank you won't see this happen unless the boat is totally unstable anyway. But that means a DIY WTC.

[sub john]

HI TOM
      I think doing model submarines is very much some times a compromise in trying to get it to work half right, it must be really nice to try the sub in a swimming pool like what i saw on your video and to be honest i thought it worked very well, and i did notice when you emptied the tanks it did tilt to the left looking from the back of the sub. Do you use a tube for your water tight compartment i myself like the idea of using  a flat plate bonded in to the hull on the water line as it makes the sub more stable but like i said it some times has to be a compromise and it is very much the same some times messing about with electronics.


       yes you are right about surface tension holding the deck to the surface of the water when trying to completely blow the tanks, this again was a major problem with the big sub to sort this one out  i had to drill hundreds of half inch holes in the deck so the air could escape  when diving  and when surfacing to let the air back in on top of these holes is all the wood planking so you can not see any of the holes but the air can come in and out between the planks of wood on the deck. I spent 2 weeks planking that deck and would not like to do it again
               All the best John

[timgarrod]

Popped round today to see how John was getting on with the build(only to find the Mrs spraying the boat  )

not long till finished

[salmon]

Coming along nicely. Love the monitor too!

[thegrimreaper]

Big subs and BIG pets John lol nice monitor


Regards Mark

[timgarrod]

few more photos of the desk sprayed

[sub john]

HI Salmon
      It's a lot of work to get to this point to be-able to spray it i don't think the weld lines have come out to bad on the hull, glad you liked the bosc monitor but he is still a baby at 14 months, but we will have to make sure there is no cats in the garden when he goes out or he will look at it as DINNER they move very quick as they will catch a rabbit
                       All the best Sub John

[sub john]

HI Mark
       Yes you are right big subs and big pets the trouble is he is still growing and got another year and a half growing time to go. He is lovely natured but a lot of them can be nasty i didn't think i would get another reptile like Gizmo the bearded dragon we lost last year but you have to spend time with them to make them what you won't them to be.


       I have thought about training him to go after surface boats and sinking them all i would have to do is put a prawn on  the back of a model boat in a pool and he would soon get the idea that the boat has food on it and all he has to do is catch it to get the food lol but only joking
            All the best Sub John

[timgarrod]

deck now painted