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Author Topic: Ok... Don't laugh...  (Read 3241 times)

Lash151

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Ok... Don't laugh...
« on: February 28, 2013, 02:53:49 PM »

...I have been designing a simple ballast system for a model sub... I know I should just go and buy something complete...but I like working stuff out and building it myself... Anyway, this would take the sub from waterline to decks awash... then it would dive dynamically... Would it work?  :embarrassed:




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dreadnought72

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Re: Ok... Don't laugh...
« Reply #1 on: February 28, 2013, 03:48:08 PM »

Two thoughts:

1/ You don't need the snorkel. Just vent the air into the (sealed) hull. Then you could make it dive more than dynamically.

2/ I shudder to think of the stress on that poor servo. Why not replace it with a geared, high-torque motor driving a threaded rod?

Andy
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Lash151

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Re: Ok... Don't laugh...
« Reply #2 on: February 28, 2013, 03:59:21 PM »

Yes... I did draw a version with the geared motor and threaded rod... but I couldn't work out how you stop the motor at full travel. I had a belt drive to allow for this.




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Circlip

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Re: Ok... Don't laugh...
« Reply #3 on: February 28, 2013, 04:05:19 PM »

Pair of micro switches to limit travel. Your long linkage would need a thick piston to eliminate rock.
 
  Regards  Ian
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Lash151

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Re: Ok... Don't laugh...
« Reply #4 on: February 28, 2013, 04:10:29 PM »

Pair of micro switches to limit travel.
  Regards  Ian

Yes, I thought this might be the answer... but being a bit stupid here, I cant visualise the circuit needed.
Lee
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Subculture

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Re: Ok... Don't laugh...
« Reply #5 on: February 28, 2013, 04:28:06 PM »

You told me on another forum that you have Norbert's book. If you have the circuit is shown in that book.

The idea you have shown won't work, as normal hobby servos have insufficient torque to actuate a piston directly at that lever length.

Just stick with a dynamic diver until you're comfortable with all the other facets of operating a sub.

Lash151

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Re: Ok... Don't laugh...
« Reply #6 on: February 28, 2013, 04:46:03 PM »

If you have the circuit is shown in that book.

Yes, you're right...
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dreadnought72

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Re: Ok... Don't laugh...
« Reply #7 on: February 28, 2013, 05:10:06 PM »

Yes, I thought this might be the answer... but being a bit stupid here, I cant visualise the circuit needed.
Lee

The circuit's identical to the one I brewed up for my jib "servo", detailed here. An ESC does the dirty work of driving the motor - though a servo-controlled switch would work - while microswitches and diodes prevent overruns.

Andy
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SwedishProjectBuilder

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Re: Ok... Don't laugh...
« Reply #8 on: February 28, 2013, 05:19:45 PM »

Hello,
Iam in the process of building a ballasttank and have made one before.

As someone earlier stated, you are not in need of a vent. The air "in the tank", when at surface, is compressed into the submarine hull and providing a small counter pressure when submerged. (only good)

One servo wouldnt be enough. Maybe in a very very very small tank, but the best solution (in my opinion) is the geared version.
I would also recommend a longer piston if your using a o-ring to seal.
There is different ways to "stop" the piston and the threaded rod.
In my very first ballasttank I simply took away the threads on the rod at the locations where it was in either max/min. Thereby the threaded gear couldnt push it further. And then you can have some sort of spring pushing the gear to get grip again when going back.


In my new one there will be a switch solution.
The other way is (as mentioned) the switches with a circuit.
My current project:
http://www.modelboatmayhem.co.uk/forum/index.php?topic=39075.0

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Lash151

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Re: Ok... Don't laugh...
« Reply #9 on: February 28, 2013, 06:13:02 PM »

I recently posted on the Sub Driver Forum... (as Subculture pointed out)... The general consensus there, seemed to be to not go the experimental, build it yourself and learn by your mistakes approach, but to start simple... they are probably right... but how did all this start? Surely someone at some point, over a pint in the pub, drew a model sub on the back of a beer mat?  :-)
Lee
 
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Subculture

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Re: Ok... Don't laugh...
« Reply #10 on: February 28, 2013, 06:55:51 PM »

Yes, because back in the day, if you wanted a model submarine, the only way to get one was to roll up your sleeves and build one.

But it wasn't arrived at over a couple of beers. It took many years of hard work, failure and cold hard cash to get to the stage we're at today with well developed dive systems and reliable methods of sealing.

Lash151

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Re: Ok... Don't laugh...
« Reply #11 on: February 28, 2013, 07:03:13 PM »

Yes, because back in the day, if you wanted a model submarine, the only way to get one was to roll up your sleeves and build one.

But it wasn't arrived at over a couple of beers. It took many years of hard work, failure and cold hard cash to get to the stage we're at today with well developed dive systems and reliable methods of sealing.

Sounds great... Its a bit of a shame that everything has already been worked out!  :-)
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VC

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Re: Ok... Don't laugh...
« Reply #12 on: February 28, 2013, 07:06:09 PM »

Have you seen this?

http://www.youtube.com/watch?v=0wBa7w7-DZs

I am going to start work on this soon.

Cheers!
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VC

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Re: Ok... Don't laugh...
« Reply #13 on: February 28, 2013, 07:13:20 PM »

This a classic and it is right here :

http://www.modelboatmayhem.co.uk/Builds/U789/1ndex.htm


Cheers!
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Lash151

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Re: Ok... Don't laugh...
« Reply #14 on: February 28, 2013, 07:32:34 PM »

They are two really good links... thanks VC  :-))
Lee
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dreadnought72

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Re: Ok... Don't laugh...
« Reply #15 on: February 28, 2013, 08:18:03 PM »

This a classic and it is right here :

http://www.modelboatmayhem.co.uk/Builds/U789/1ndex.htm


Cheers!

I was 21 when that was published, and I remember it very well. Der Kapitan demonstrates the perfect attitude to model-boating!

Andy
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Mad_Mike

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Re: Ok... Don't laugh...
« Reply #16 on: March 01, 2013, 12:03:27 AM »

hi lash i like your thinking, it is a case of reinventing the wheel but fear not as i am guilty of it too. You should see my centrifugal jet boat, it turned out that a conventional jet worked a lot better, fancy that!!! %%  Im no sub expert i just understand the basic principles but id go with  a bladder myself. I think it would be a lot easier to manufacture.
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Lash151

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Re: Ok... Don't laugh...
« Reply #17 on: March 01, 2013, 12:39:48 AM »

Hi Mike...
Yes, I do enjoy figuring things out myself. Some help along the way is good but I don't have the money or the inclination to buy a complete working sub system... it would spoil the fun of trying to invent one.  :}
Lee
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Subculture

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Re: Ok... Don't laugh...
« Reply #18 on: March 01, 2013, 12:03:49 PM »

Throwing up ideas and sketches on a forum to solicit feedback is not what I consider to be invention, it's consultation.

There are many different types of people in this hobby. I'd say the majority are interested in scale replicas, and concentrate on the external hull, which relies more on conventional modelling techniques. When it comes to innards, they just want something that works reliably and is well proven in the field.

Then you get other sub modellers who are more interested in what goes on inside the boat. These parts have more to do with model engineering than the craft side of modelmaking.

There is a rare breed who take an interest in both, and fully scratchbuild their models, I can think of maybe a couple dozen submarine modellers worldwide who do this.

If you want to scratch build, start with a dynamic diver. From that you will hopefully learn how to make a watertight compartment, with reliable shaft seals. If you leave a suitable 'space' in the middle of the boat, you can add a ballast system later on.

Davy1

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Re: Ok... Don't laugh...
« Reply #19 on: March 01, 2013, 02:02:50 PM »

Hi Lee,
I wouldn't be discouraged and feel that "everything has already been worked out" in model submarines. There is plenty to develop and improve. However best to find out what is current knowledge and build on that. ("Stand on the shoulders of giants" is the phrase that comes to mind but no real giants in this hobby and they are mostly friendly!)
Having said that it is not very easy to get knowledge of model submarines.Working model submarines are still rare, rather surprisingly, with lots of "vanity" projects stuck on shelves or being flogged off on ebay. Model submariners are still thin on the ground and don't meet or communicate that much  and form lots of little groups. The web and the AMS do their bit but there is not much chance to look and touch.
Could I suggest that you pop along to the Norwich Sub weekend this summer? I think that Norwich MBC may have done us all a favour by providing a perfect gathering place.
See you,
David
 
 
 
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Lash151

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Re: Ok... Don't laugh...
« Reply #20 on: March 01, 2013, 02:22:38 PM »

Throwing up ideas and sketches on a forum to solicit feedback is not what I consider to be invention, it's consultation.

There are many different types of people in this hobby. I'd say the majority are interested in scale replicas, and concentrate on the external hull, which relies more on conventional modelling techniques. When it comes to innards, they just want something that works reliably and is well proven in the field.

Then you get other sub modellers who are more interested in what goes on inside the boat. These parts have more to do with model engineering than the craft side of modelmaking.

There is a rare breed who take an interest in both, and fully scratchbuild their models, I can think of maybe a couple dozen submarine modellers worldwide who do this.

If you want to scratch build, start with a dynamic diver. From that you will hopefully learn how to make a watertight compartment, with reliable shaft seals. If you leave a suitable 'space' in the middle of the boat, you can add a ballast system later on.

You're right on all counts... I know I am not inventing anything and yes, I should start with a dynamic diver...which I will. I think I just have too much computer time on my hands at the moment as my workshop is out of action! Sorry if I have come across as a bit of an idiot...  :embarrassed:   I shall get building and shut up!
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SwedishProjectBuilder

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Re: Ok... Don't laugh...
« Reply #21 on: March 01, 2013, 04:02:09 PM »

Sorry if I have come across as a bit of an idiot...  :embarrassed:   I shall get building and shut up!
I myself is mostly in this hobby because I like the engineering part. "inventing" (get inspiration and make your own version) is the fun part for me!
Since Im also very new to this and dont possess an engineering degree (yet, studying my second year), I love to hear new ideas!
I also love paint pictures  :}
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Subculture

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Re: Ok... Don't laugh...
« Reply #22 on: March 01, 2013, 10:51:58 PM »

The only real major development I've seen in model subs over the years has been improvements in the electronic items. We have better levellers, ESC's, ballast control, batteries etc. Those have come about as a direct result of miniature computers like PIC and Atmel controllers becomign available.

In terms of the mechanical aspects of subs e.g. ballast systems, enclosures etc. I think things are basically the same as they were back in the day. Some things, like commercially available miniature air pumps have helped the hobby, as years ago these had to be scratchbuilt, or made on a cottage industry level (expensive) and the internet has made it much easier to find the items you need.

When I first started in this hobby, the internet was still very young and the only source of information was groups like the AMS, Sub Committee etc. plus the odd magazine article. Norbert's book- which was freshly published in the mid-nineties- helped a great deal, but I think it still assumes a certain amount of knowledge.



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