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Author Topic: INVINCIBLE Too!  (Read 5786 times)

Geoff

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INVINCIBLE Too!
« on: March 07, 2018, 02:16:41 PM »

As a follow up to Nick's build of his Invincible I have also started building this model.


The plans came from an old source "Sambrook" and are very detailed and are drawn to a scale of 1/192 so standard side. I'm building Invincible as a match for my Iron Duke so the same scale at 1/96 which gives a model length of 72 inches. I said I wouldn't build a bigger model than Iron Duke (78") so its true!


I started using the same building blocks I used for ID so the process is very similar albeit the hull shape is very different which became apparent when planking commenced.


the fundamental difference was that Battlecrusiers were derived from armoured cruisers and not battleships so the hull form is both narrower and has a much easier entry and exit form which is particularly noticeable at the stern where the hull lines are really quite fine.


Progress was the same as with ID albeit once planking was completed I found a distinct twist in the forward port side of the hull which caused a lot of extra work to correct - I still don't know why!


On the basis of a picture tells a thousand words please see attached.


I'll follow up with progress in due course.


Cheers


Geoff
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Geoff

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Re: INVINCIBLE TOO!
« Reply #1 on: March 07, 2018, 02:19:47 PM »

More pictures. One of them with all the clamps looks very strange indeed. Also shown are the brass stem and stern pieces using flat brass strip annealed and bent into a "U" shape and further annealed and bent into shape.


Cheers


Geoff


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Dreadnought

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Re: INVINCIBLE TOO!
« Reply #2 on: March 07, 2018, 02:45:09 PM »

Looks good Geoff  :-)) :-))
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Tug-Kenny

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Re: INVINCIBLE TOO!
« Reply #3 on: March 07, 2018, 02:49:07 PM »

 
Excellent piece of woodworking.  She looks very smart.

Following with interest.

ken
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Bob K

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Re: INVINCIBLE TOO!
« Reply #4 on: March 07, 2018, 02:58:35 PM »

Geoff:  Fantastic so far  :-))  I shall be watching this build with great interest, hoping to learn some tips for my own build.  I saw your Invincible quite recently and was hugely impressed.  I know you will be building in your unique gun fire system, which looks so realistic on HMS Iron Duke.

Thank you for sharing your build sequence, I am looking forward to seeing more progress,  O0
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raflaunches

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Re: INVINCIBLE TOO!
« Reply #5 on: March 07, 2018, 04:05:19 PM »

Hi Geoff


Thanks for starting your build log too, itíll be great as a comparison of build techniques that we both employ to get two Invincibleís on the water. I canít believe the amount of detail the Sambrook plans go into and it took me a little while to ensure I picked the correct items for the 1914-5 Falkland fit. The serious lack of photos from this particular era of the ship can be annoying as I have only found 2-3 pictures of any real help for details of the forward superstructure.
Anyway, Iíll speak to you when I return from Cyprus in a couple of weeks regarding the guns, Iíve just been informed by my parents that the thermistors have just turned up yesterday from China! I ordered them when you send me the link!
Keep up the good work  :-))
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Geoff

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Re: INVINCIBLE TOO!
« Reply #6 on: March 07, 2018, 04:55:26 PM »

Nick,

More pictures to follow shortly. I agree there are very few pictures of Invincible. The book British Battlecruisers by John Roberts (latest addition) has copies of the builders plans of Invincible and the side elevation is draws to 1/192 scale so is a perfect match.

One of the things I'm thinking about is building her after her refit in Malts when the fore funnel was raised by 15 feet but that's a long way in the future.

I've been struggling with the gun turrets as there are two distinct types on Invincible. I spent ages making wooden roofs (for better insulation) but fount I couldn't fit the gun mechanism in once it was insulated so reverted to alloy roofs as they are much thinner and can be bent to shape and are "springy" so when screwed down they fit better. I also gain about 2.5mm which is enough!

Cheers

Geoff
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ballastanksian

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Re: INVINCIBLE TOO!
« Reply #7 on: March 07, 2018, 09:51:08 PM »


Yes, two turrets were from Armstrongs and two were from Vickers (If I recall correctly) all being built with experimental electrical systems rather than all hydraulic, with disappointing if sparky blue results  {:-{


It's excellent to see another capital ship build. I can't wait to complete my little ships so I can add an armoured cruiser to the mix.
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Capt Podge

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Re: INVINCIBLE TOO!
« Reply #8 on: March 07, 2018, 10:11:04 PM »

That's a fantastic start to your build - looking on in awe (envy). :embarrassed:

Regards,

Ray.
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Geoff

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Re: INVINCIBLE TOO!
« Reply #9 on: March 08, 2018, 01:45:19 PM »

Okay, some more pictures including the one with the bow and stern frames this time!
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Geoff

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Re: INVINCIBLE TOO!
« Reply #10 on: March 08, 2018, 01:58:06 PM »

One more brings me virtually up to date. I'll try to post some more pictures of the gun turrets and main engines shortly. The turrets were very challenging to make with their awkward shape. I used 1.5mm ply for this in two layers. the inner layer lower so with the outer layer higher I created a step inboard for the roof to sit in. As mentioned I found the wood roofs took just too much space so replaced them with thin alloy which sits on the outer edge which wasted all the work in creating the ledge in the first place!


We all live and learn.


The next steps are:


1) Build the actual gun components. This is virtually all done but I need to carry out some tests to see then new (different) and somewhat smaller thermistors work okay. So far some experiments have not proved too encouraging!


2) Install the sub decks to carry the turret barbettes - these will be attached to the main deck so it all comes off in one piece.


3) Start plating the hull on the outside with plastic card. As usual I will only be doing the outs-strakes. As it happens the portholes are all in the out-strakes so I will be cutting the holes before I fix the plating. This way if a porthole is not in alignment I just replace the plate.


4) Work out the turret turning mechanism - I'll probably winch them round as per my usual method but I mau only need to turn "P and Q" 90 degrees as it would prove very complex to turn all four turrets to one side due to the geometry of the layout.


Cheers


Geoff









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Geoff

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Re: INVINCIBLE TOO!
« Reply #11 on: March 08, 2018, 02:28:49 PM »

Just by way of clarification, I prefer to build large models upright because the deck line and sheer is very important as if wrong its almost impossible to correct at a later date. Any hull imperfections can be sanded and filled. I start the planking with a single continuous plank at the waterline then plank upwards with shorter lengths. This gives rigidity to the whole structure. I then plank downwards for 2 or 3 planks. Then a single plank on the bilge line again for rigidity. This also defines distinct areas to plank using shaped planks.


The deck is a continuous piece where possible with the deck openings partially cut through so the whole still behaves as a single piece which prevents warping and twisting.



Finally I always make sure I have roof to get my hand inside to release the hull from the keel blocks, then turn it upside down and complete the planking - then lots of sanding!


Cheers


Geoff
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ballastanksian

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Re: INVINCIBLE TOO!
« Reply #12 on: March 08, 2018, 09:36:16 PM »


I hope you can get the thermistors to work Geoff. I love those turrets and can see the subtle differences between type.



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Geoff

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Re: INVINCIBLE TOO!
« Reply #13 on: March 12, 2018, 01:26:04 PM »

Some progress over the weekend. I  have remade the turret roofs in alloy. The two different shapes are readily seen. Also note the turret with the lagging for the heat exchanger.


In the foreground are the thermistors and the heat exchanger units. Note the sideways fluid injection pipes which make the whole unit about 1/5cm shorter which eases installation.


Also visible is the central tube which will carry the wiring downwards beneath the sub deck.


Main engines are two interior car blower motors from an old Talbot Horizon. They are 12/14 volt twelve pole motors which I run on six volts. This is an identical installation to Iron Duke.


The rudder posts (sorry about the feet!)


Cheers


Geoff
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raflaunches

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Re: INVINCIBLE TOO!
« Reply #14 on: March 12, 2018, 03:58:21 PM »

Nice work Geoff :-))


Iím looking forward to returning home so I can continue with mine. After reading your log so far Iíve realised that weíll be able to distinguish the two Invincibleís now- Iím going for the short fore funnel whilst youíre going for the raised. Itíll be interesting to see the differences when they are together.
Keep up the good work!
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Nick B

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Bob K

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Re: INVINCIBLE TOO!
« Reply #15 on: March 12, 2018, 05:58:34 PM »

Excellent work Geoff.  She looks very impressive.  Nice workmanship  :-))
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ballastanksian

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Re: INVINCIBLE TOO!
« Reply #16 on: March 12, 2018, 09:44:43 PM »

I reckon the two part roofed turrets are more attractive than the others. It is all looking fab Geoff.
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Geoff

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Re: INVINCIBLE TOO!
« Reply #17 on: March 14, 2018, 02:20:23 PM »

I'm going to have to start thinking about how I intend to turn the turrets. The basic system will be the same as Iron Duke. A small sail winch pulling the turrets round with fishing line.


The Invincible turret layout caused considerable complications as "P" (port side) can only turn to starboard if "Q" (Starboard side) is in a certain position because of the length of the gun barrels.


It may then only prove practical to fire three guns on any side so how do I control the guns?


"A" and "Y" need to be able to rotate 180 degrees but "P" and "Q" only need 90 degrees so I can probably control these with separate engines and gearboxes and micro switches. However it occurred to me that if I link "A" and "P" together with a single cord then if I turn "A" to port ten "P" will slave but there would then be no way to make "P" return to the centre line unless I used a spring and a cord pulling in the opposite direction.


So as "A" returns to the centre line the rotate cord would be slacken but a spring on the other side would rotate the turret back to the centre line at the same speed as "A". As "A" continues to turn to starboard the pull line would be slack so no rotation of "P" beyond the centre line.


"P" would not "spring back" because the pull line would stop this happening as it would be fed out slowly. The only downsides I can think of is that it would impose additional strain on the sail winch (because of the spring) and if there was any sticking in "P" it could cause a jam or a jerky movement.


Hope that description makes sense! I think I'll have to make a dummy and see if the concept is viable.


Cheers


Geoff
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dreadnought72

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Re: INVINCIBLE TOO!
« Reply #18 on: March 14, 2018, 08:16:33 PM »


You know the real answer by now, surely?  %)


Andy
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ballastanksian

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Re: INVINCIBLE TOO!
« Reply #19 on: March 14, 2018, 09:55:36 PM »

Geoff. If the turrets are not heavy, they should not need a heavy spring to control their return to centre especially as their rotation is on a vertical axis and not a horizontal one. A light spring may even be better as then it isn't pulling on anything to force the pivot towards the force exerted by the spring possibly causing it to stick or force the turret to tilt.
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Geoff

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Re: INVINCIBLE TOO!
« Reply #20 on: March 15, 2018, 02:29:13 PM »

Okay by way of an update I now have a number of various PTC Thermistors for trial. The original ones I used in ID were 6cm x 2cm x 0.5cm and were rated for 230 C. I can't purchase these anymore so did some hunting around and found some alternatives:


1) Those shown in the picture next to the turrets 3cm x 2.5cm x 0.5cm rated at 220 C


2) Some older ones which are in a flat sleeve and are 6cm x 1cm x 0.3cm rated at 200 C


3) Some new ones which have just arrived 5cm x 2cm x 0.5cm rated at 230 C


4) The original ones 6cm x 2cm x 0.5cm rated at 230 C




They are all different with different characteristics and cable thicknesses. I've tried out 1) and whilst they certainly get hot it doesn't seem as hot as I would have thought. The trouble is there are various permutations to contend with - current consumption, surface area and rate of heating/time. So I've decided to take the plunge and have ordered a pyrometer to measure the actual temperatures so a series of experiments coming up:


Test the originals as I have one spare and I know these work perfectly. Check the current consumption every 20 seconds, final current consumption, temperature reading every 20 seconds and final temperature.


This should give me some parameters to play with when doing a comparison with the others so I can put this on a spreadsheet to see temperature rate and final temperature, time frame and current consumption.


I can then repeat the experiment with the thermistors strapped to the heat exchanger and measure the temperature of the heat exchanger, current consumption and time.


What I suspect is that whilst the smaller thermistors reach the required temperature the rate of conductivity to the heat exchanger is less as the surface area is less so the rate the heat exchanger heats up will be different. Depending on ambient air temperature its possible the heat exchanger will never get to the right temperature as the heat loss from the exposed surface will exceed the thermistors capacity to provide heat! However this would all be different once there is insulation so may just be a time issue.


I hope to be able to provide some guidelines for which thermistors are best suited to this process.


I'll report back later!


Cheers


Geoff


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ballastanksian

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Re: INVINCIBLE TOO!
« Reply #21 on: March 15, 2018, 08:57:50 PM »


Have the original thermistors disappeared completely, or are they only available in multiple thousands as a commercial order for a distributor?


As an example, My Dad's Stihl chainsaw suffered a cracked silencer about twelve years ago and I could only buy them from China in lots of a thousand! Luckily a friend of mine knew someone who could tig weld and so I did not need to buy enough silencers to build a shed from.


(It was a very old saw that was not available in the UK due to the lack of anti-vibe mountings.)
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Bob K

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Re: INVINCIBLE TOO!
« Reply #22 on: March 15, 2018, 10:24:51 PM »

The original thermistors are no longer available - I bought the last four - one reason my build will have four firing turrets out of seven.  The other reason being the weight of additional batteries.
I will follow this evaluation with great interest as a workable equivalent could be important to anyone considering this awesome gun fire system.
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Re: INVINCIBLE TOO!
« Reply #23 on: March 15, 2018, 10:34:37 PM »

Check this guy out on eBay for a range of thermistors

http://stores.ebay.co.uk/spsemporium/Heaters-/_i.html?_fsub=953396719

Unless you remove the inner part from the outer metal can you can't really see what the size of the actual heater elemement is, the inner element is nearly always much smaller than the outer case

This guy lists 12volt 230 degree @£5.00 https://www.ebay.co.uk/itm/Aluminium-Encased-Compact-PTC-heaters-5V-50-C-12V-60-C-12V-80-C-12V-140-C-/281401112183

C-3PO

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C-3PO

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Re: INVINCIBLE TOO!
« Reply #24 on: March 16, 2018, 07:32:57 AM »

4 week delivery from amazon

£3.68 - 2 pieces delivered - 12v 220 degree 330x240x40 -

https://www.amazon.co.uk/Adhere-Fly-Accessories-Applicable-Miniature/dp/B01N7SSYH5/ref=sr_1_4?ie=UTF8&qid=1521185100&sr=8-4&keywords=ptc+heater+12v&dpID=41RucdfHfJL&preST=_SY300_QL70_&dpSrc=srch

Many variants available via the net - lots are long delivery time



C-3PO
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