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Author Topic: Resurrecting the K Class  (Read 10652 times)

Martin (Admin)

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Re: Resurrecting the K Class
« Reply #100 on: March 05, 2017, 06:18:33 PM »


Third Repeat post 
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derekwarner_decoy

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Re: Resurrecting the K Class
« Reply #101 on: March 06, 2017, 12:31:05 AM »

Morning Subculture :o...I must admit of not knowing that Willie of the Shakesphere wrote or penned that phrase {-)

We think of manganese and Naval Red brasses as brittle, however such a propeller casting that has been machined would have surprisingly high impact resistance and fracture or shear strength properties

My only constructive thought is that with some 2000 tons of mass possibly pivoting on the propeller blades when the vessel came to rest is that one if not more of the blades became grossly distorted %)

This may have distorted the propeller blade geometry as depicted in the image of the beached submarine

Derek
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Ian K

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Re: Resurrecting the K Class
« Reply #102 on: March 06, 2017, 06:48:40 PM »

Hi,

Just to add my view on the prop issue......

The K boat pictured is fitted with 3 blade screws, don't confuse the mud/sand bar she has settled in as a 4th blade.
Subculture is correct, with his 120 vs 90 degree line image.

But, some K boats were fitted with 4 blade screws, so what ever layout Bob has decided to depict will be fine in the end  ok2

Good work up to now Bob, keep on plugging away!

Ian
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Colin Bishop

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Re: Resurrecting the K Class
« Reply #103 on: March 06, 2017, 07:27:45 PM »

Sorry Ian, but if you look at the image in the link I posted it quite clearly says K4 on the conning tower and there is an unmistakeable 4 bladed prop hanging off the port shaft! I have copied the image below.

Most Ks were 3 bladers I think but K4 when she went aground had 4 bladers.

Colin
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Ian K

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Re: Resurrecting the K Class
« Reply #104 on: March 06, 2017, 08:26:37 PM »

Hi Colin,

Nothing to apologise for!

I was basing my observation purely on the image Bob posted and the blade center angle comments from Subculture.

A friend of mine, scratch built a K boat at 1/48th scale many years ago. From builders drawings, It featured all the working gubbins such as retractable funnels, guns and vent shutters etc. It was a big beast!

I wish I could find the old 35mm film prints I took of it, when he exhibited at the Blackpool Tower show, in the circus ring pool back in the old days.

Ian
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Subculture

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Re: Resurrecting the K Class
« Reply #105 on: March 06, 2017, 09:06:44 PM »

I would say you need to look more closely at that picture Colin. It hasn't modified my point of view in the least. The second blade is partially submerged in the water, in the same position as the shot taken from astern. When you offer up a 90 degree angle to it, the centre of the second blade is not inline.

I'm not going to waste my time posting up more pictures to support my opinion, as they just get deleted.

Martin (Admin)

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Re: Resurrecting the K Class
« Reply #106 on: March 06, 2017, 09:26:00 PM »



Tell you what Bob, put a three blader on one side and a four on the other!   ok2
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Bob K

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Re: Resurrecting the K Class
« Reply #107 on: March 06, 2017, 09:41:22 PM »

Thanks Martin    {-)  {-)  {-)

People are welcome to their opinion, but stating it once is more than sufficient.

In my view, and it is my build, the rounded four blade propeller is totally different to the more pointed three blade of the wreck of K17.   The photo is not at right angles to the keel so superimposing lines can only be subjective.



We can agree to differ, but in my view it is clearly a four bladed propeller.

Can we please move on.  I am making some good progress on installing the telescopic shafts.
 
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Re: Resurrecting the K Class
« Reply #108 on: March 06, 2017, 10:08:40 PM »

I have had a similar issue with the SS Ohio build. I am in opposition to ALL other models built of the wartime conversion to Ohio, and any sketches showing the bridge details, and I guarantee you I am right. We know our specific model better than anybody else ( unless they have built one also! ), and are sure of all the details...but should be open to all alternatives, just in case some new evidence comes to light. I have about eight photos of Ohio as converted..the odd image has started to surface thanks to the Imperial War Museums Archive becoming available on line, but nothing helping me find two rogue 20mm Oerlikons..


Good luck with the build, stick to your guns but always keep an open mind :-))
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Dr.Schmidt

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Re: Resurrecting the K Class
« Reply #109 on: March 07, 2017, 08:47:39 AM »

The nice thing about props is, that they usually come with a threaded hole, which makes them exchangeable, e.g. from 3 to 4 or the other way around.......just as a hint. 
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Ian K

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Re: Resurrecting the K Class
« Reply #110 on: March 07, 2017, 05:56:46 PM »

Hi,

Just a technical blurb link to the K class boats.......

http://www.histarmar.com.ar/InfGral/SubmarinosK/(1915%20-%201931)%20K%20&%20K26%20Class.htm

It may help, if you have not got this info.

Ian

Edit:


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Bob K

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Re: Resurrecting the K Class - Shafts
« Reply #111 on: March 08, 2017, 04:15:24 PM »

HMS K9.  Shafts

I am trying to replicate the square telescopic prop shaft couplers ingeniously used by ‘Albion’, although with less space to play with.  Cut the nylon dog-bone couplers in half, cut square flats so they fit in the square brass tubes, then drill and tap for size 0 x 6.4mm stainless s/tap screws.  I sourced just the right sized stainless springs from inside Biro’s.  One square shaft slides over the other making 50 mm from dog-bone pin to pin with the spring compressed 30%. 

The purpose of this is to ensure a pressured ‘rattle free’ connection, yet allowing enough latitude to remove the dive module. 



Next I can start to install the fixed prop shafts in the lower hull.  There is a slight angle, and I have used the coupler shafts to equalise the angle, half on each dog-bone.  The shafts pass through the hull at a very shallow angle so long slots were needed.  A temporary jig was made to adjust/set the positions of the shafts.   The shafts and tubes can then be shortened to the correct length. 


Using jig to finalise positions of shafts before setting in hull.

Quite a bit more work to do before finalising shaft positions, but you can see my method.
Slots need lengthening even more, but am starting to get alignments nearer to ideal.  Prop shafts in surface warships are a whole lot easier.   O0


PS:  Generic information on a class built across seven shipyards is useful, but not definitive of specific ships.  Although based on Vickers drawings each yard utilised their own techniques and parts.
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derekwarner_decoy

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Re: Resurrecting the K Class
« Reply #112 on: March 08, 2017, 10:46:28 PM »

Bob...being a Plan view, this hull space appears to be a free flooding water compartment when the K Class is submerged?...... would the compartment also be water filled/partially filled when the submarine was on the surface? ........Derek
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Bob K

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Re: Resurrecting the K Class
« Reply #113 on: March 09, 2017, 07:49:29 AM »

Derek:  All shaft components outside the sealed dive module are at the bottom of the hull and would therefore be under water even when surfaced.  I appreciate the need for waterproof grease and very frequent maintenance under these conditions.  I have seen a similar system used so it should work.

I am determined to complete this vessel and get it on the water.  Minimum goal is to have it surface running, but static diving if I can get it properly balanced and ballasted. 
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Re: Resurrecting the K Class
« Reply #114 on: March 09, 2017, 08:52:07 AM »

The compressible drive shafts idea should be credited to David Merriman of Sub Driver fame, i just used square section brass to avoid the need for drive pins.




See attached recreation of the infamous photo, looks nothing like the real thing :(
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Davy1

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Re: Resurrecting the K Class
« Reply #115 on: March 09, 2017, 09:24:53 AM »

Hi Bob,

I wouldn't worry too much about maintenance (greasing etc) of your prop shafts.

By their nature model subs spend far more time out of water than in it. Make things so that water drains out and they can dry.

David

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Bob K

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Re: Resurrecting the K Class
« Reply #116 on: March 09, 2017, 09:43:14 AM »

David:  Good advice.  I have a big slot directly under that end of the dive module, in the keel.

Albion:  If it was David who first created this drive system, fair enough.  At least it shows I am using the intended methodology  :-))
However with so many joints it is proving to be hard to get everything to line up properly

It beats me why people cannot clearly see the propeller blades in that photo, they are quite distinct.  When I have my drive shafts and rudder installed I will post a photo for comparison. 

I will not build the rudder and rudder support 'keel' until I have the shafts set, then the shaft supports last.
My shafts look a bit oversize externally, but that can't be helped.
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Re: Resurrecting the K Class - Shafts
« Reply #117 on: March 13, 2017, 02:53:09 PM »

HMS K9.  Shafts

It took quite a bit of fiddling, and keep lengthening the slots to eventually become 90 mm long, such was the shallow angle through the GRP hull. 
I had to make a jig under the stern to position the shaft ends, and use some temporary Plastruct “U” channel forward to equalise the dog-bone joint angles as much as possible.  To avoid having the spring end floats to contend with as well I temporarily replaced the internal springs with plastic rod.
The parallel motors are on 25 mm pitch, and the shaft ends at 38 mm pitch.



Now I can secure the shaft outers in the hull with f/glass resin and matting.  The outer exit profile will need pre-shaping with Milliput before matting in.  It will not be possible to recreate the original exposed shaft arrangement due to the position of the dive module and sprung telescopic connectors leaving almost all the shaft outers outside the hull.

When this part is completed I will make up the rudder and skeg keel extension.  The rudder is almost at the end of the slender ‘duck tail’ stern. 
As I can’t fit an appropriate mixer I am tempted to make the rudder oversize to improve its natural poor turning circle. 

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Re: Resurrecting the K Class - Progress & Milliput
« Reply #118 on: March 18, 2017, 11:08:46 AM »

Progress

Please appreciate that this submarine is not a “kit”.  I am fitting a dive module into a unique GRP hull, so just about everything apart from the module and GRP mouldings will be virtually scratch.  On top of which my experience in submarines is limited.
There are two subs at our club, a thunder tiger and an OTW Upholder Class.  The later is very impressive and I am grateful to its owner for helping me understand how it goes together.  Having an SLA battery in the flooded bow seems a neat idea.  On Sunday he showed me how the numerous linkages worked, something I need to design / machine / silver solder next.
BTW: OTW do a massive French Surcouf submarine cruiser, and an X craft.  Both over fifteen hundred quid, but very nicely engineered.

Milliput problems

Having secured the prop shafts in place with f/glass matting and car body filler inside.  All I had to do was create a smooth exterior contour.  Normally Milliput is just the job.  Can be worked with the fingers, smoothed with water, and can be sanded in about three hours. I have used it on many occasions before.
However !    Despite buying a new pack, and carefully kneading equal parts until even colour, after four days it was still rubbery and impossible to sand. 
I can only assume it had been on the shelf too long.  It happens.
So, picked out most of the Milliput with a screwdriver and rebuilt the external curves with Z-Poxy resin and fine matting.

Finally, I am now building the shaft end supports with soldered brass tubes. 
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Re: Resurrecting the K Class
« Reply #119 on: March 18, 2017, 05:06:32 PM »

Sounds like a dodgy batch to me Bob. I have bought a couple of packs from model shops before now that perhaps did not get much passing trade for epoxy putties.
I found that while they did go off, the dark (I use the grey/yellow variety) part had a resiny skin on it and was quite hard, while the yellow part was very slimy and, as a result, did not want to mix with the other part even if that was warmed to soften.

I expect through our hobby carreers, we will all buy one pack of dodgy putty and it will always cause much grief.

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Bob K

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Re: Resurrecting the K Class
« Reply #120 on: March 18, 2017, 06:26:45 PM »

It did feel a little dry and a bit harder to knead.  There is no sell-by date, so as you say it depends how much of it they sell over time.  The only loss was a week of build progress. 

Now I am working on how to construct the various control linkages, for rudder and two sets of dive planes. 
The rudder is in a really awkward corner at the tip of the duck tail stern.  Difficult to access.
I have bought a small pillar drill and a hand vice for it.  I am looking for brass bar of various diameters that I can drill through for rods, and use grub screws to secure.  Actuator arms will need to be silver soldered.
Control planes need to be in thin brass with soldered-in rods.  I will be making the rudder oversized as there is not enough space to fit twin ESC's and a mixer.  I still expect the turning circle to be substantial.
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Re: Resurrecting the K Class
« Reply #121 on: March 19, 2017, 10:15:53 PM »

Given the difficulty of access and the inherrent need to get it right and well set up so as to be almost maintenance free, I would try and mark the rudder mechanism so that at a certain point the rudder will be in a certain position so that if needed you would be confident that poking the right tools in the right places would allow you to remove it should damage occur beyond that which you designed redundancy for in the system. A bit like marking the timing pulleys on an engine when removing the head to repair an overhead cam etc.

Repeated testing of systems both in and out of the water will reduce the need for repair or modification of course as you well know from your efforts on Poly.

Re Putty, I am not sure where you are best going to for fresh Milliput as places like Hobbycarft may hold stocks for as long as a small model shop if the local clientel are unaware of said product. I would hope that most model shops/online stores have enough modellers who know about it to keep the stock and thus the freshness turning over.
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Re: Resurrecting the K Class
« Reply #122 on: March 26, 2017, 09:11:26 PM »

Hi bob,
 I had independent motors on my big K to start with, expecting a huge turning circle but I was pleasantly suppressed. I think it was a better than the original rudder angle.
 I'll get some photos of how I did the funnels, but a word of warning, on the bench great but after a couple of dips the gremlins start.
 Also the mould for your K class is now with me.
 Adam
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Re: Resurrecting the K Class
« Reply #123 on: March 26, 2017, 10:25:01 PM »

Thank you Adam.  Interesting about the motors and turning circle.  I was worried about that.
Anything you have on how you did the funnels would be most helpful.  I am aware that such immersed linkages will need a lot of maintenance.  Where I bought my hill mouldings, they no longer list them.  So, Mountfleet now have the mould !

ballastanksian:  I am waiting for the brass bars I ordered to arrive before starting on the linkages.  Space inside for the rudder actuator is tight, but I believe there is enough space -  Just.  Using grub screws will help access.
On the Milliput.  I have since bought a pack of 'standard' from the same model shop as the 'white'.  It worked fine, solid as a stone after 3 hours.  I asked them to check their stock of 'white'.  Open the box and give the rolls a gentle squeeze should show any that might be iffy.  My new 'standard' was super soft when gently squeezed.
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Re: Resurrecting the K Class
« Reply #124 on: March 26, 2017, 11:39:48 PM »

In a warm environment (normal warm, not tropical!) it should be like this, and easy thus to mix together with the fingers or a sculpting tool.

Like most resins, it will cure much quicker if put on a warm surface. If you have a very warm place then place the item with putty on a piece of wood first to absorb the worst of the heat. I used to put work in my car's dashboard on a hot day and it would cure in an hour.
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