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Author Topic: Resurrecting the K Class  (Read 19378 times)

Subculture

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Re: Resurrecting the K Class
« Reply #50 on: January 25, 2017, 02:50:44 PM »

A lipo monitor is available that will blow your tank when the battery cut off is reached. It's esclusive to submarines, so not particularly cheap. An alternative would be to use one of the dirt cheap lipo monitos designed for model aeroplanes which sound a buzzer when the cut-off point is reached. Remove the buzzer and have the output trigger a strobing LED, which will give you a visual clue it's time to come in.

Those motors should be fairly modest in terms of current use, especially as they'll be driving fairly small props. Lipos can deliver much more punch than other battery tech, so I don't think you need concern yourself on motor draw. However easy enough to measure once everything is set-up.

Bob K

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Re: Resurrecting the K Class
« Reply #51 on: January 25, 2017, 05:00:36 PM »

I don't want to get ahead of my step by step game plan, but I do have a "LiPo Guard" which is supposed to blow ballast on low voltage, plus a "ADF2" electronic spirit level to control the rear dive planes.  Not gone into how they wire up yet.  (Trying to avoid an all-at-once overload). 
The 3300 mAh LiPo should give enough run time then.  I made up a foam-board model to check it fits.

I am currently working on internal servo linkages.  After that I will be positioning the dive module in the hull, with centre of ballast chamber coincident with boat C of G.
After that, planning how to make up the external linkages, using magnetic couplers.

One step at a time.    Bear with me please  %%
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Re: Resurrecting the K Class
« Reply #52 on: January 25, 2017, 05:13:56 PM »

No problem with the battery then.

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Re: Resurrecting the K Class
« Reply #53 on: January 25, 2017, 05:55:51 PM »

Bob,

Whilst the Arduino is not the answer to everthing - it would certainly make an elegant and cheap solution for the Lipo cutoff voltage guard.

The basic Arduino's have 6 Analogue to Digital converters onboard - they can measure 0v -5v - so it's likely a resistor (voltage divider) will be required.

The Arduino can monitor the voltage or 6 if you wish- once the cutoff voltage is reached you can have it blow the tanks, sound an alarm , flash an LED or all 3 at once

Might be worth contacting JohnRedEarth or tscenecal ( Mayhem handles) as Arduino's and Subs are right up their street.

Googling "Arduino Lipo voltage cutoff monitor" or the like would shed some light of the subject

C-3PO

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Re: Resurrecting the K Class
« Reply #54 on: January 25, 2017, 06:24:34 PM »

When you are packing 10 pounds or Kilos into a 5 pound or Kilos space, the addition of arduino added complexity. True Arduino can do a lot for subs and are being used, but right now Bob is working through the basics of getting a sub to work. Both electronic pieces are great and will keep his sub running level (ADF2) and battery safe (LiPo Guard). I use those as well as MicroGyros products.


Bob, your doing good. Take it one step at a time and remember when it gets frustrating the goal is to finish it.
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Bob K

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Re: Resurrecting the K Class
« Reply #55 on: January 25, 2017, 06:46:52 PM »

C-3PO:  If I was building HMS X-1, like Nick's (raflaunches) Dad Steve then your turret rotation programme could have been very useful.   I will be putting the Arduino turret system into the 7 foot HMS Agincourt.

Salmon:  Quite right.  I have more than enough complexity with the items I already have to shoehorn in there.

My HMS Polyphemus project was an experience that I believe now makes this one possible, a semi-submersible that took ages to get working, and sank twice, but succeeded in the end.  Knowing that a positive outcome is achievable with enough tenacity gives you a lot of confidence. 

Beware, HMS K9 will eventually be visiting a lake near you  :-))

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Re: Resurrecting the K Class
« Reply #56 on: January 26, 2017, 10:41:49 AM »

I think that Bob is doing exactly the right thing in his circumstances i.e get something simple  together and working.

After that you can add complexity. If you are going that way and wish to add Lipos etc. I would suggest going the 433/458 MHz receiver route (developed by Tim Senecal) Lots of advantages for submarines including sending you Lipo voltage (and current draw, compass direction, depth etc) Small and cheap equipment too even with an extra Arduino for telemetry.

I haven't used 40Mhz for about 3 years now. Lipo monitors/ shut offs etc. are also a thing of the past.

But yes Bob, get it together and get it working on 40MHz first.

David
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Re: Resurrecting the K Class
« Reply #57 on: January 27, 2017, 04:36:34 AM »

stay with the lipogard..sorry for the poor quality of the picture..my daughter suggested I do it in pain and save it.please be gentile I did the best I could for the 1st time and a 13yrd artist is a brutal critcic hahahah {-) the lipo gard need no set up  when low voltage it locks out the vent/ blow servo preventing you from diveing..when added to the fail safe side of the adf2 the failsafe will trigger the blow signal to the gas tank if submerged.(I don't know this for fact but I am guessing it knows submerged or not by the activity of the angle driver..if your on the surface the boat will be mostly level,no angle driver activity...submerged.pitch will be changing so it over rides stern servo to keep the model level so active signal).the stern plane servo goes directly to adf2 angle side then the adf2 to your stern plane and vent blow servo channels.this is how I did mine for reference..you will have to set up the angle driver for zerobubble ..and senseitivaty..isolate the adf2 from vibration as much as possible.and you will have to turn down the sensitivity..i had to go to lowest setting as the vibration of full millatary power on the moters can cause the servo's to twitch and the esc to stutter..(don't ask me how I know this) hope this is better than the drawing..
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Re: Resurrecting the K Class
« Reply #58 on: January 27, 2017, 07:07:04 AM »

I am extremely grateful for your efforts in producing this circuit diagram roadrunner440.   I am nowhere near the wiring up stage yet, but have saved your illustration in my "K" photo album.  It does explain a lot.  Thank you.
There are numerous "odd" flying lead ends on some of the units. 

My first LiPo has arrived.  It fits, just!.  I know everyone will assure me it will not need an underground bunker to charge it, but I am nervous of these things.  I spent most of yesterday polishing and working in servo pushrods through their seals.  More later on that 3D wire puzzle, but going well so far.
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Re: Resurrecting the K Class - Servo rods
« Reply #59 on: January 27, 2017, 02:33:11 PM »

HMS K9.  Servo rods

Only 2 of the four servo rods were long enough, so I had to remake the other two from 1/16 inch brass rod.  Initially the rods were very tight in the seals so I started by carefully polishing those with a fine abrasive pad.  I need to strike a careful balance between just free enough for the servos to slide in them, but not too much so the seals could leak.  Once a reasonable slide had been achieved, working them further using Vaselene eased the action a little more.  This took most of Thursday and part of today.

Next was shaping the rods to the servos, having carefully looked at the various photos kindly posted.  None is quite like my set up, so I am using general principles.  The rods must move as axially straight through the seals as possible, not foul each other or the Rx, and allow full angle of movement on the arms.  It is like trying to solve a 3D wire puzzle.  Two big motor capacitor solder blobs were in direct line of the outer rods and had to be routed around.  Still needs a little tweaking.



I am buying a 4 channel servo tester so that I can check out the operation of these, without having to wait until the rest of the electrics are commissioned. 

This compartment contains most of the major challenges, and will be very tight for space once everything is fitted in and wired. 

I am making some progress though . . . . . .

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Bob K

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Re: Resurrecting the K Class - Lipo
« Reply #60 on: January 27, 2017, 03:20:25 PM »

HMS K9  - Lipo

Quick update.  Photo showing the 3300 mAh LiPo battery in forward compartment, which just fits as you can see.
I made up a foam board model before ordering just to check.





PS:  Yes, my Avatar has changed, to the unofficial ships badge of HMS K9.  The motto scroll says "CANINE", and the name "GARM" is the huge dog that guarded the gates of hell in Norse mythology.  All puns, the commander had a sense of humour  {-)
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Re: Resurrecting the K Class
« Reply #61 on: January 27, 2017, 05:49:31 PM »

yay progress..as to the batt I recommend you get another and series them I can post a pic fo how I did it,,as to a good balenceing charger I recommend the thunder tiger .it will put up the model # when I get home. it works on ac/&dc comes with a power supply cord(most lipo chargers don't it also does sla /lipond lion/NiCad/nmhi batts as well it will relace all your other chargers..and reasonable cost mine was 110$ usd..I am overly paranoid about lipo's as well..don't use if dropped. I charge mine out side in the yard in a brown planter pot at a low c rate.and have never had a problem with any of the 3 sets of paired batterys I have ...I did however buy a parallel balenceing bord adapter  to use with my thundertiger ac/dc tp610...because the charger only has 1 balanceing port..but the bord was like 12$usd on ebay....keep plugging.after what I saw with the polymus boat you got this... :-))
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Re: Resurrecting the K Class. Servos testing
« Reply #62 on: January 28, 2017, 07:09:20 PM »

HMS K9.  More progress

I have an all-types programmable charger, suitable for LiPo’s, a SKY RC e6650.  At this point I will keep to a single LiPo.  No point in complicating things.  Apart from new identical SLA’s I am dubious of parallel battery connection with the risk of one battery back charging the other.  I have one boat with twin NiMh’s, and use an Action P103 which has dual 20A Schottky diodes and heat-sink to prevent this. 
With LiPo’s?  No way !

Anyway, the little servo tester arrived.  Cost under a Fiver.  I can test each servo separately or in groups with only a 4.8V Rx battery plugged in.  No point in starting on major wiring until I can prove the servos can work the push rods OK.  With push rods operation checked out I can now hot glue the servos in place.

Planning ahead to position the dive module in the hull.  Loose fitted all the internals in the tube, and marked the C/L of the ballast chamber.  Tube volume 8.98 Litres and weight 1.10 Kilos.  The 53 inch hull is only 727 gm and will be free flooding. 
To say the module is a close fit is an understatement.  It virtually rests on the hull bottom with the hull top a close clearance. Very little fore/aft adjustment possible either, allowing for coupling the drive dogs to the props.  I intend copying the sprung loaded sliding square tube idea previously posted by Albion.

So, getting the C/L of the ballast chamber in line with the overall C of G will be near impossible in practice.  I foresee a lot of trial and error with pink foam and lead.  Too long for the bath, I will have to build a lined box for water tests.  Hopefully this can later convert to a transport box.

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Re: Resurrecting the K Class
« Reply #63 on: January 30, 2017, 04:13:26 PM »

For those not aware yesterday was the centenary of the Tragedy of HMS K-13
sinking yards of the shore  on a test dive in the Gareloch 32 killed 48 saved
A service was held at the Navy's Faslane Base


https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=sinking+of+K-13in+1917
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Re: Resurrecting the K Class
« Reply #64 on: January 30, 2017, 05:06:08 PM »

A sad anniversary indeed.  The class were so much larger faster and more complicated than any previous submarines that they suffered numerous catastrophes, collisions, and sinkings.  Having steam engines and funnels was perhaps amongst the least of their technical problems.  Designed to operate with the fleet as if a group of destroyers was asking for trouble, especially at night.  Their maximum safe diving depth was less than half their 338 feet length.
Read the fascinating book "K Boats" by Don Everitt.

I am building HMS K9, which at least survived to be scrapped in 1926.
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Re: Resurrecting the K Class
« Reply #65 on: January 30, 2017, 07:33:54 PM »

Can we see some pictures of how far out the cylinder position is going to be. This is a crucial element in how your boat will look and perform on and under the water. It's not the same as making a boat, even one with a variable displacement, they are much more forgiving.

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Re: Resurrecting the K Class
« Reply #66 on: January 30, 2017, 10:01:22 PM »

Fair comment Andy.  I will take some pictures tomorrow and add dimensions.  The WTC tube has 3 compartments.  Battery section 6 inches, ballast 12 inches long, and motor volume about 9.5 inches.  Most of the weight is in the rear compartment.  So with almost everything in the dive module it's C of G is four inches aft of the C / L of the ballast chamber.  Quite a lot.

If I add more weight to the battery compartment so C of G & C/L are the same point would that aid positioning the WTC in the hull ?   
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Re: Resurrecting the K Class
« Reply #67 on: January 31, 2017, 04:42:24 AM »

The cylinder in M1 is as low in the hull as it can go, the front and rear of the cylinder are just clear of the hull, with just enough clearance under the mid section to fit some lead sheets. My first cylinder mounts had the module higher and more central radially, but that really doesnt work
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Re: Resurrecting the K Class
« Reply #68 on: January 31, 2017, 08:01:16 AM »

Don't worry about the weight balance of the cylinder, just concern yourself with the position of the central ballast tank.

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Re: Resurrecting the K Class - Dimensions
« Reply #69 on: January 31, 2017, 10:12:55 AM »

HMS K9.  Dimensions

Albion:  Not sure how similar the K and M class hulls are.  M1 was 45 feet shorter and a couple of feet narrower.  However, getting a 2,5 inch dive module in there leaves little latitude for moving the WTC around.

First picture shows my dive module, with inner lengths of compartments. The centre of the ballast chamber is 12 inches from the front.   I have loose fitted almost all the components, and the centre of mass is almost 4 inches rearward of that.



With the tube laying in the hull it is a close fit inside.  There is about 3 inches fore / aft movement possible between the forward hull narrowing and before prop shaft exits become impractically close to the rear.  Maybe up to half an inch of vertical movement under the hull top.  Moving the tube back and forth within its limits make less than an inch difference to the overall C of G balance point.  Hull mass is only 727 gm.



I hope this explains it a bit better.  It does not seem possible to get the C of G coincident with the centre of the ballast chamber without getting the rear of the dive module well aft of the prop shaft outlets, where the hull is far too narrow to for it anyway.
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Re: Resurrecting the K Class
« Reply #70 on: January 31, 2017, 02:16:13 PM »

With the current arrangement you will have to either accept a very unscale like waterline with the bow up in the air and the stern squatting down in the water, or the c.o.g is going to have to be moved further forward than is desirable. A far forward c.o.g will make the boat more forgiving, but it will make the boat tend to weathercock more when turning, and will make it less agile.

There are alternative solutions, but they would involve radical alteration of your present dive module, which I can quite understand you would be reluctant to do.

The chap that owns Mountfleet models scratchbuilt a K-class in a larger scale. You may wish to get in touch with him via his website contact and pick his brain on the handling.

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Re: Resurrecting the K Class
« Reply #71 on: January 31, 2017, 03:11:51 PM »

Woops, looks like I have problems then.  I am unsure what battery (and therefore weight) was intended for the forward compartment.  (LiPo's could not be shipped from the States.)  Maybe a lot heavier than the 3300 mAh I am using?  Why else was the ballast chamber centred so far forward?

Silly question (please excuse me) but with just a 150 gm bag of lead shot low in the point of the bows I CAN get the combined hull and dive module to balance longitudinally right under the centre of the ballast chamber, with just enough room to connect prop shafts. 

I understand that not only should it be on a level keel on the surface (with empty ballast tank) but should remain on a level keel when submerged.  Catch 22 to achieve ?

Would my extra 150 gm in the bow still balance it with a half full ballast tank, provided the o/a ballast centre remains over the C of G ?
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Re: Resurrecting the K Class
« Reply #72 on: January 31, 2017, 03:39:41 PM »

I don't disagree you can get the boat trimmed. What you're not taking into account is that there are three main sets of forces acting on a sub which affect the way it handles (affects boats too, but the affects are a little more benign, at least at low speed).

You have gravity pushing down and buoyancy pushing up, these are static forces, and with the two aligned on your boat surfaced and submerged, it should maintain an even keel no matter where along the keel those two forces align.

The third force is pressure acting on the hull as it moves through the water. A dynamic force that dictates heavily how the boat will handle. Ideally on most subs the centre of pressure will be acting a bit forward of the longitudinal centre of the boat. If it's aft of centre the boat will be unstable and skittish, further forward and it will be more stable, too far forward and it'll be too stable.

BTW. Not  sure what you used to calculate the volume of the cylinder, but no way is it 8.98 litres. I calculated 2.2 litres.

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Re: Resurrecting the K Class - bulkheads
« Reply #73 on: February 03, 2017, 09:24:21 PM »

HMS K9.  Bulkheads

OK.  Dive module positioning is defined by Hobson’s Choice.  The ballast chamber being so far forward in the tube, plus the unknown weight of the battery that it was designed for.  150 gm of lead low in the bow the only way to avoid having the tube almost hanging out the back of the hull, but at least the centre of the ballast chamber matches the overall C of G, and allows prop shafts to be fitted, albeit very short ones. 
I really do not expect a K Boat to steer well, the real ones didn’t, and had volatile pitch control.  It is after all a long thin spindle with a tiny rudder and planes.

Taking advice I will try to mount the tube as close up under the upper hull as possible, but no higher than the surfaced waterline.  Three supporting bulkheads, the centre one being positioned for the dive module alignment spigot hole. A Velcro strap will go around the centre of the tube.  The supporting bulkheads are taking time to shape. “U” shaped cutouts for the tube will be added, plus holes to allow water flow and reduce weight.



Positioning the “U” cutouts will be critical, there is not a lot of clearance.
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Re: Resurrecting the K Class - Bulkheads part 2
« Reply #74 on: February 14, 2017, 02:08:19 PM »

HMS K9.  Bulkheads Part 2

Sorry for the delay.  Forming those bulkheads took a lot longer than I thought.  Loads of intricate internal measurements and calculations as the hull shape precluded use of profile tools. The aim being to get the top edge of the dive module about 5 mm above the intended waterline.  However, it is still very close to the bottom GRP hull.

I also had to allow for the lower hull needing to be pulled in a little at the top, to line up with the upper hull edges.  This involved making a fourth bulkhead.  Each bulkhead had to be fitted and epoxied as a separate operation, with the dive module in place to ensure an accurate fit, with localised hull width clamping.



Next up will be constructing the 60 inch long test tank, which will later double as a transit case. 

PS:  The special 2A switches with boots, (manufacturers part numbers were quoted in the SubDriver data,) duly ordered from the USA - finally arrived.   From Thailand !!!
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