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Author Topic: Darnell U-570  (Read 13963 times)

kazzer

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Re: Darnell U-570
« Reply #25 on: October 13, 2010, 03:13:46 AM »


The main consideration is in deciding whether to stick to a radio box or change to a WTC. Hmm.....decisions.

Thanks guys keep them coming

Phil.

It was that awful Darnel box that finally got me to consider a cylinder. I tried to make up one I purchased in bits, but it was awful. I eventually found D&E and that how I got into selling their stuff.  I persuaded them to make the 3.5/2 Sub-driver into an economic kit, and its been very successful. Put a Snort system in there and you've got a REAL submarine. Pm me for details
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kazzer

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Re: Darnell U-570
« Reply #26 on: October 13, 2010, 03:23:15 AM »

Hi Phil.
           I had the idea of chopping a mountain bike inner tube and using it as a gasket seal for the perspex hatch.

                 wonder wot the experts think of that.

                                       cheers Frank

              

Terrible idea, been there done that - and as I sell Darnell models, I've seen and heard of several people  using the boxes. THEY SUCK!  I told  MBD to not supply them any more, and I believe he took my advice. Get a cylinder! Get a Snort ballast system. You'll love it.
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RonP

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Re: Darnell U-570
« Reply #27 on: October 14, 2010, 10:15:16 AM »

Phil,
100 for a U-boat is a pretty fair deal as far as I am concerned, you did good but you do have a fair bit of work to do.  If those rubber bellows are still OK then wash them in soapy water (soap, NOT detergent) and guard them with your life, they will be the original SHG bellows and have not been available for some years now and they were the best around for our purposes.
A number of people have run down the original Darnell system but in fact it wasnt that bad if you have patience. The bag was originally forward of centre and this did cause trim problems
as it made the C of G way to far forward, later on he provided two pressure hulls with the bag placed central this was a big improvement. I may have one of the original USL pumps in my junk box that you are welcome to and the bags are STILL available from SHG so you could restore it to original format if you wanted. If you have a little money to spend you can buy one of a dozen ready made modules that will slot straight in. The original single 540 motor will do the job but if my memory is correct the ones Darnell used were 23 turn motors and used a lot of current (around 10 amps) under load so a better solution would be to use a couple of 545 motors one to each prop or for a bit more money you get a lot more motor if you use a couple of Agrachi motors from Ron Dean (Deans Marine) Hope this helps.
Ron Perrott
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kazzer

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Re: Darnell U-570
« Reply #28 on: October 14, 2010, 10:57:06 AM »


Don't want to hijack your thread Phil but who else has built a Darnell sub?

I 90% finished Ulholder ( HMS Uncertain

Where did you get the gun?  Is it home made?
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Martin [Admin]

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Re: Darnell U-570
« Reply #29 on: October 14, 2010, 11:44:17 AM »

Where did you get the gun?  Is it home made?

Yes, a poor effort but I was proud of it!
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Flying Sparks

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Re: Darnell U-570
« Reply #30 on: October 24, 2010, 04:26:50 PM »

Well, I've read Norbert's book and I have a better idea of how a submarine works although I can't claim to understand everything in the book, my eyes glazed over at some of the math. However, it was a good read and will make a good reference book even if some of the electronics is a bit dated.

As for U-570 one of the decisions is made for us (it's a joint project between myself and teenage son Michael. Michael is the brains and chief driving force and I'm the chief sponsor and transport provider) the watertight box is coming away from hull so we will replace this with a cylinder. The ballast system is not decided yet but  it will be either a piston tank or air bag. We had a look at the Engel piston tanks, very nice but a lot of money. If anybody knows where we can find a design we could build our own piston tank to that would be very nice. The ballast tank of whatever type we decide on will be fitted at the c of g to prevent any unwanted trim changes when diving.

For the WTC we can get some 100mm x 3mm acrylic tube on ebay for about 15 and a friend is willing to let me use his lathe to make some end caps.

Lots more to plan design yet but we are getting closer to actually making a start.

Many thanks to all the people who have helped and made many suggestions here on Mayhem and at Brockwell  :-))

Phil.

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Subculture

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Re: Darnell U-570
« Reply #31 on: October 24, 2010, 07:13:59 PM »

I have some literature on how to make your own piston tanks. It's in German I'm afraid, but the drawings and pictures are largely self explanatory, and I have translated much of the text with the assistance of google (foreign languages aren't my strong suit I'm afraid)

You will need a lathe to make the piston and the endcaps for the tank. You can make a tank for under 20, electronics are extra, but will not be too expensive- a pair of micro switches on a servo can be used, or you can build the servo control board featured in Norberts Book.

Flying Sparks

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Re: Darnell U-570
« Reply #32 on: October 24, 2010, 07:56:39 PM »

Quote
I have some literature on how to make your own piston tanks. It's in German I'm afraid, but the drawings and pictures are largely self explanatory, and I have translated much of the text with the assistance of google (foreign languages aren't my strong suit I'm afraid)

You will need a lathe to make the piston and the endcaps for the tank. You can make a tank for under 20, electronics are extra, but will not be too expensive- a pair of micro switches on a servo can be used, or you can build the servo control board featured in Norberts Book.

Subculture

A freind has kindly offered the use of his lathe so we should be good to go and build a piston tank, I think we will buy in the electronics if possible to do so at reasonable cost.

Cheers

Phil.
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Mankster

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Re: Darnell U-570
« Reply #33 on: October 24, 2010, 07:57:31 PM »

The ballast tank of whatever type we decide on will be fitted at the c of g to prevent any unwanted trim changes when diving.

Many thanks to all the people who have helped and made many suggestions here on Mayhem and at Brockwell  :-))

Phil.



You'll be wanting to set the ballast tank at the centre of bouyancy, not the centre of gravity. With a single ballast tank you will be moving bits of foam about to alter your centre of bouyancy to to match the position of the ballast tank.  The location of the center of Gravity will determine how agile or otherwise your boat will be (COfG forward = more stable/less agile).

Subculture

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Re: Darnell U-570
« Reply #34 on: October 24, 2010, 10:04:02 PM »

I would aim to place the centre point of your tank where the number '7' is painted on your conning tower.

Electronics for your tank. Most of the piston tank control boards come from Germany, where this system is most popular. There are various versions, prices tend to range from about 25 to 50, depending on whether you want proportional control or simple bang-bang command of the piston tank.

g4yvm

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Re: Darnell U-570
« Reply #35 on: June 06, 2011, 01:29:02 PM »

I wonder if this project was completed?  The photos are very useful to me as a beginner in subs, really good stuff!  As a result of reading it I have bought the book by Norbert Bruggen...

Looking inside the Darnell hull I see why people go for the WTC these days...thats a LOT of bolts to work through to get into the box isnt it??  Very interesting photos of the internals though I do not yet understand what I am looking at.  Is that TWO watertight boxes, a clear plastic ballast tank and a wet hull?  I cant see a piston in the tank so I am assuming it is a total-loss gas powered tank (or using the pump as mentioned in the thread -  drawing wet air back into one of the boxes, which seem to me to be linked via a flexi hose).

That model engine carby...is that an air dump valve for diving?


I can also see that most of the decking flood holes are not cut away.  It looks odd but done for ease I suppose.

D
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thegrimreaper

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Re: Darnell U-570
« Reply #36 on: June 06, 2011, 02:42:29 PM »

I think David that the system in use on this project is a gas system ala the real thing valve opens to let water into the ballast tank for submerge the cannister in the picture is possibly a can of propelant (the type used for spray guns)when you want the sub to surface you command a rise on the sticks and a squirt of gas enters the ballast tank and because its under pressure forces the water out so as to surface the sub this type of control is primarily used in in the U.S of A
main problems (so I have read ) is you need to keep a count of surface/dive number because if you run out of gas while submerged the boat wont surface

Regard Mark
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g4yvm

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Re: Darnell U-570
« Reply #37 on: June 06, 2011, 02:48:15 PM »

Mark,

Thanks for that.  It does seem to be a very realistic system, but the scale maneouvre of being stuck on the bottom is one I'll pass on!  The piston pumps seem to be the logical way for a model to work to my untutored eye!

I'd like to see how its all progressed though!

D
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thegrimreaper

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Re: Darnell U-570
« Reply #38 on: June 06, 2011, 03:19:33 PM »

Piston pump's are good (so I have heard) My Akula uses a ballast tank with a water pump with a pinch valve to dive pumping the water in pressurises the air in the tank when the sub dives the pump stops pumping and the pinch valve pinches the water tube so as to not let the water out which is now under pressure on a stick command the pinch valve opens and the under pressure water exits the tank the sub rising as it do's is a very simple and cheap system which can have its own fail safe built into into

Regards Mark
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g4yvm

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Re: Darnell U-570
« Reply #39 on: June 06, 2011, 03:32:58 PM »

That SOUNDS very simple to say but complex to make.  any pics?

D
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thegrimreaper

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Re: Darnell U-570
« Reply #40 on: June 06, 2011, 07:36:55 PM »

I hope this link works.  http://www.servimg.com/image_preview.php?i=984&u=15029581

the picture was taken by myself and shows to the left the water pump on the lower right is the pinch valve with the home made cam that operates from a servo to pinch the tube inside the valve housing the micro switch also operates off the cam to power the pump to pump water to the ballast tank switch is off pinch valve is open to expel water and surfice the boat
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Flying Sparks

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Re: Darnell U-570
« Reply #41 on: June 06, 2011, 07:43:30 PM »

Quote
I wonder if this project was completed?  The photos are very useful to me as a beginner in subs, really good stuff!  As a result of reading it I have bought the book by Norbert Bruggen...

The Darnell Vllc is myself and son Michaels project. not a lot has happend since my last post. We have slowly been collecting bits, we bought an Engel dive tank and a 9 channel 40mHz receiver. I have also aquired a lathe that I can use to manufacture a lot of components.
We have done some work on the hull, the watertight box has been ripped out and the inside of the hull is being cleaned up. The WTC material is about to be ordered. Photo's to follow.

We will be at St. Albans Dive in on Saturday, meet you there.

Phil.
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g4yvm

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Re: Darnell U-570
« Reply #42 on: June 06, 2011, 08:22:23 PM »

Ok, see you there.  I'll be in a grey G4YVM tee shirt!

D
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Davy1

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Re: Darnell U-570
« Reply #43 on: June 07, 2011, 09:33:45 AM »

I've just been reading through this thread again. Very interesting to see a Darnell model being reborn and could I say 100 very well spent!
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