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Author Topic: INVINCIBLE Too!  (Read 13108 times)

Geoff

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Re: INVINCIBLE TOO!
« Reply #25 on: March 16, 2018, 08:39:14 AM »

Thank you, I searched both e-bay and amazon but couldn't find many that suited once you specify 12 volts. The trouble is having found some that work there are no identifying codes on them to track identical ones down so you are going by appearance.

I did some small testing last night and some almost immediately draw 6-7 amps climbing to 9amps and heat up very quickly. Others which have a higher temperature point draw only 2amps but candidly beyond the point when a drop of water spits on contact I can't tell their actual temperature.

The ones Bob got certainly work but I haven't seen them for sale again - Bob do you have the "address" for those you could post?

Cheers

Geoff
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Bob K

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Re: INVINCIBLE TOO!
« Reply #26 on: March 16, 2018, 09:42:01 AM »

Sorry Geoff.  I usually file component invoices but I can't find that one.
I know the ID code on the order form was 191953139182, the same as yours, and that it came from China via E-bay.
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C-3PO

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Re: INVINCIBLE TOO!
« Reply #27 on: March 16, 2018, 09:46:22 AM »

Hi Geoff,

I appreciate you have been working on this for a long time so may be teaching you to suck eggs - sorry!

When searching in Google playing with the search phrase can help - try PTC HEATER 12V  or PTC HEATER 230 and then click on the "image" tab in Google

I have several thermistors of varying sizes - all 12 volt

I have found that often the outer slip case may be a different size but the actual element placed inside is the same - i.e. the element does not fill the larger cases.

Have you removed the element of the ones you have had success with? If so what are it's dimensions?

The other thing is you can get physically smaller 220-230 degree 12v so this may be an advantage as they have the same wattage so the same heat output into a smaller chamber may be an advantage.

I guess the other advantage of the smaller size thermistor is that they may be a ble to be used in smaller models/ give you more room to play with...

I am sure you have been through these hoops already

Regards
C-3PO
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Geoff

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Re: INVINCIBLE TOO!
« Reply #28 on: March 16, 2018, 09:47:28 AM »

Likewise - I just checked and when I hit the details it just comes up as "IP address no longer recognised or some such"

I guess we just have to buy when we see them. It never actually occurred to me they would not be available in the future - I guess we live and learn. Mind you how many working battleships do I intent to build! Ah , yes, I'd better start searching now!!
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Geoff

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Re: INVINCIBLE TOO!
« Reply #29 on: March 16, 2018, 09:51:56 AM »

C-3PO - thank you for your input, I'm just glad for any suggestions on the gunfire mechanism - I'm sure that between us all we can find multiple solutions!

I'm very happy for people to make any suggestions and improvements as the idea it to make this system available to as many modellers as possible - you can't have too many battleships firing at each other on the pond!  :-)
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C-3PO

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Re: INVINCIBLE TOO!
« Reply #30 on: March 16, 2018, 10:07:58 AM »

Geoff,

The innards of a thermistor - you can see the outer case is larger than the element - this is a 12v 230 degree specimen



If you wanted you could do away with outer case and simply insert the wrapped electrodes and thermistor directly into your heat block


I think you may find that there are standard sizes of the actual element (small medium etc) that you then see for sale in an assemblled case - if the case looks different from you original purchase the internal element may be the same in others that are available just that the original case was designed for a specific application and that's not available

C-3PO
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C-3PO

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Re: INVINCIBLE TOO!
« Reply #31 on: March 16, 2018, 10:55:48 AM »

Geoff,

Another term to use when searching is "PTC Aluminum Ceramic Heater"

They are so widely used you won't have a problem finding them (Curling tongs, Hairdryer, glue gun, yoghurt maker, coffee machines etc etc etc) - biggest challenge is finding 12 volt versions - but many exist

This is a manufacturer - I guess they only deal in high volume sales but interesting none the less

http://www.ptcthermistorheater.com/

http://www.ptcthermistorheater.com/products.html

http://www.ptcthermistorheater.com/sale-7642081-low-voltage-ptc-ceramic-heater-ptc-thermal-resistor-high-efficiency-with-insulating-film.html

C-3PO
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Geoff

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Re: INVINCIBLE TOO!
« Reply #32 on: March 16, 2018, 01:37:36 PM »

Thank you for all the responses - yes I have taken one apart and one type I have are only in the plastic sleeve so are readily accessible. I had thought of doing away with the case and in fact you could go further and do away with one of the electrode plates and use the heat exchanger as the earth/negative. A little awkward though if you get a short!


If you take them apart there are typically little ceramic tablets and I guess you could use these in different configurations by adding more of less tablets to create your own. It opens the door to all sorts of experimentation! I think you can purchase just the tablets themselves but I have no idea as to the specifications. Would more tablets create more heat or less?


Cheers


Geoff
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C-3PO

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Re: INVINCIBLE TOO!
« Reply #33 on: March 16, 2018, 01:53:42 PM »

Hi Geoff,

Will be fascinating to follow your testing.

The other thought I had was does it make sense to preheat your smoke fluid - if the fluid was already warm/hot would this make a difference with volume of smoke? Maybe worth a try

C-3PO
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Geoff

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Re: INVINCIBLE TOO!
« Reply #34 on: March 16, 2018, 02:05:05 PM »

An interesting thought but my suspicion would be that it won't make any real difference as the "action" takes place as it flash vaporises so to preheat the fluid may mean the heat exchanger could be less hot, saving power, but you would use power to preheat the fluid so the same overall dynamic. It will always take a certain amount of power to change the state of a liquid to gas. The only differences will be the time and the temperature of the gas and I guess the ambient temperature of the fluid which would probably only vary by about 1O/15 C.


I've also been looking at 3D printer heater heads/units as they are self contained and operate in the 230 C range to melt the plastic. Without some very complex scientific experiments I think it will be really quite hard to "prove" one way or the other. As above  It will always take a certain amount of power to change the state of a liquid to gas.
 
Lots to think about!
 Cheers
 Geoff

Fonts Fixed.  :-)
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Geoff

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Re: INVINCIBLE TOO!
« Reply #35 on: March 16, 2018, 02:06:36 PM »

The last sentence was meant to say "it will always take a certain amount of energy to convert a given volume of liquid to gas at a given temperature in a given time"
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Bob K

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Re: INVINCIBLE Too!
« Reply #36 on: March 16, 2018, 05:11:10 PM »

For those who may not have seen Geoff's HMS Iron Duke in action, here is another photograph from Wicksteed.



The original thermistors may have been production over-run for a specific design application, the surplus being sold off on E-Bay. 
I am sure Geoff will be able the replicate its superb efficiency once he finds a suitable replacement for his HMS Invincible.
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C-3PO

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Re: INVINCIBLE TOO!
« Reply #37 on: March 16, 2018, 05:22:38 PM »

Sorry Geoff.  I usually file component invoices but I can't find that one.
I know the ID code on the order form was 191953139182, the same as yours, and that it came from China via E-bay.

Hi Bob,

Just a thought - all eBay transactions are in your account history ( which can cause a problem when you share an eBay account!!!) - you should be able to locate your seller there

C-3PO
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Bob K

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Re: INVINCIBLE Too!
« Reply #38 on: March 16, 2018, 07:24:19 PM »

Good idea C-3PO.  The seller was "sellerbible (368677)",  and I have sent them a message
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C-3PO

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Re: INVINCIBLE Too!
« Reply #39 on: March 16, 2018, 07:37:28 PM »

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Geoff

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Re: INVINCIBLE Too!
« Reply #40 on: March 19, 2018, 08:50:34 AM »

Some more pictures. The turrets have now been completed. The patchy paintwork is just the first coat and I will spay over to get a much better finish. Note the different turret designs with P and Q being wider. The round circles on P and Q are for 4" secondary guns with the strips for foot strips.


The 4" guns on A and Y were re-sighted in the forward superstructure.


P and Q turrets sit on cradles fixed to the underside of the main deck. This was very fiddly work and took hours to do to ensure the turrets has sufficient clearance and aligned with the barbettes. This also gives me a gap below the cradle where I may be able to fit in some batteries.


I carried out some tests over the weekend with the various thermistors and will report back shortly on the results.


Cheers


Geoff



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Geoff

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Re: INVINCIBLE Too!
« Reply #41 on: March 19, 2018, 01:31:30 PM »

As referenced I have been trying some experiments with various thermistors and have now purchased an infra-red temperature reader so I do some more experiments.


Per the attached picture and chart this was the result.


The most unusual result was with the 3D printer heater units. Research showed that most 3D printers operate in the 250c range so I was expecting similar temperatures - well I had to put the fire out when it reached 550c! So I built an alternative design of heat exchanger with the barrel offset to make room for another 6mm diameter hole to take the heater unit.


It does work but I need some more experiments to see how well as whilst the heater unit gets very hot its volume isn't all that big so its ability to heat a block of alloy to 230c is suspect albeit with adequate insulation this may change.


It has the advantage that the unit can be made smaller as no piggy back thermistor but may have a serious disadvantage as how hot will it get? Does anybody know if these heater units are thermistors with a maximum self regulating temperature or do they need to be controlled in some way?


On another note we have speculated that with the Invincible turret layout it would be awkward to get a four gun broadside however now that I have built the turrets it is quite possible provided the P and Q turrets point the other way round. On most pictures Q turret is shown as pointing aft and P pointing forwards. If this is reversed and A and Q linked they can turn to port provided Y and P are pointing fore and aft. These can then be turned to port but to deploy to starboard P and Y must first be turned beck to the centre line then A and Q back to the centre line then P and Y can turn to starboard followed by A and Q.


It sounding complicated but readily doable without using an Arduino. Basically there is just enough clearance for the guns with this method.


P and Q turrets are based on a cradle which is hung from the deck - it took hours to adjust this to give the correct clearance but this does mean there may be room for batteries to slide beneath.


More work needed!


Cheers


Geoff


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Bob K

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Re: INVINCIBLE Too!
« Reply #42 on: March 19, 2018, 01:39:19 PM »

Good idea C-3PO.  The seller was "sellerbible (368677)",  and I have sent them a message

Well, I received a prompt reply, considering the weekend got in the way.

"Dear Sir.  Sorry we no longer sale this item."  It was worth trying.

It is now up to Geoff's research into a workable equivalent.
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C-3PO

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Re: INVINCIBLE Too!
« Reply #43 on: March 19, 2018, 02:01:23 PM »

Geoff,

The 3d printer heater I think is a traditional coil heater embeded in ceramic in a metal case - sure some Googling will give you the answer...

But they are interesting - the one you have I would guess is 12v 40 watt ( so draws 3amps 'ish ).

You can get 60 watt and 100 watt (long body). ( Google - Dernord Cartridge Heater 12V 100W)

Here's the confusing bit - 3d printers have got temperature control and to do this they use - "a thermistor" - but not as you know it!!!!

The temperature control uses this type of thermistor sensor where different temp = different resistance which you can measure and therefore determine temperature.



A Controller senses the resistance and can control power to the heater to maintain desired temperature



Another suggestion for your melting pot - could you spray the fog fluid into the heat chamber rather than squirt?

C-3PO
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Geoff

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Re: INVINCIBLE Too!
« Reply #44 on: March 19, 2018, 02:14:46 PM »

Thank you, much as I thought. I'm in the process of "Googling" - indeed you could use a NTC thermistor as a temperature probe so as the heat rises so does the voltage until the "electrickery" shuts the power down or reduces the voltage which would have the same effect. So a feedback circuit is needed to control the heat. A simple bi-metallic switch could also be used via a relay but this would add volume to the apparatus. Hmm how small can bi-metallic switch be these days??

However, much as a cigarette lighters spark is in the region of 1,000c, its capacity to directly heat anything is minuscule. So if I switch the 3d heater on inside an alloy block how hot will the alloy block get. If we had 100% perfect insulation then eventually the alloy block should get to 550c or whatever the maximum temperature the heater unit will get to - time would also be a question. In practice this would all be limited by the rate of heat loss by the alloy block so in practical terms may be self regulating from a gunnery perspective as the firing cycle every 10/20 seconds would reduce the temperature. In theory as time goes by the battery voltage would drop and therefore the ultimate temperature would be reduced/drop/stabilize.

Lots to think about here and I guess I'll just have to build one and test it!

More thoughts welcome!

Cheers

Geoff
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C-3PO

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Re: INVINCIBLE Too!
« Reply #45 on: March 19, 2018, 04:02:16 PM »

"a feedback circuit is needed to control the heat"



or



C-3PO
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Geoff

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Re: INVINCIBLE Too!
« Reply #46 on: March 19, 2018, 04:07:47 PM »

Yes, "Electrickery!"
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Geoff

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Re: INVINCIBLE Too!
« Reply #47 on: April 03, 2018, 01:58:11 PM »

Some progress over the Easter break - nothing else to do other than walk in the rain!


Three funnels made and a start on the secondary armament. Six of these need to have the case-mate interior built in and the gun breaches as they will be visible from outside at certain angles. The case-mates for these ships were weather protection only so I believe they would have been open at the rear.


The brass drums are the gun shields which have since been drilled with three oblong slots - central for the gun and one each side for the gun sights which would be visible from outside.


All very awkward as these guns also need to be able to turn (not powered) for realism.


Despite having a copy of the original plans (scale 1/192) I'm having difficulty in interpreting the precise structure between the funnels. I'm not certain its just skid beams or a walkway between the two funnels.


Cheers


Geoff

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Re: INVINCIBLE Too!
« Reply #48 on: April 03, 2018, 03:26:36 PM »

Hi Geoff


See if this picture is of any help. I have tried to find clearer pictures but there are always boats in the way!
Have you seen the amount of tiny mushroom vents on the deck? Iím slowly going mad making hundreds of the little blighters!


113_D493_D_1_F5_C_4_BE2_93_D3_7_A3248_E76_D9_D" border="0
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Colin Bishop

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Re: INVINCIBLE Too!
« Reply #49 on: April 03, 2018, 05:15:38 PM »

Burt's Battleships of WW1 has drawings of the forward and after boat decks of Invincible on pages 50/51. I can't quite interpret it myself so I don't know if it is any improvement on what you already have. If you don't have the book I can scan the relevant bit.

Colin
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