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Author Topic: T.A.R.G.E.T - Rotating Seven gun turrets?  (Read 67214 times)

plastic

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Re: Rotating seven gun turrets?
« Reply #150 on: December 29, 2016, 07:54:20 PM »

You don't need a special manual mode - when the system is in its normal auto mode while sat on the desk, there no movement so there's no variable data on the compass channel - the only variable is the setting pot/stick - which is manual mode.
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malcolmfrary

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Re: Rotating seven gun turrets?
« Reply #151 on: December 30, 2016, 09:50:38 AM »

A bit of a random thought - central to the operation of big gun warships was the rangefinder.  Perhaps have that rotate, "find" the target, then have the turrets keep up with it according to their programmed ability.  Or, if the target was a radio transmitter, have the rangefinder, or a directional receiver, find and track it.

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Mr.R.Duino

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Re: Rotating seven gun turrets?
« Reply #152 on: December 30, 2016, 10:25:31 AM »

A bit of a random thought - central to the operation of big gun warships was the rangefinder.  Perhaps have that rotate, "find" the target, then have the turrets keep up with it according to their programmed ability.  Or, if the target was a radio transmitter, have the rangefinder, or a directional receiver, find and track it.


Radar - like this?

https://www.youtube.com/watch?v=rh6UxpzHlJI

NB Pretty amazing development board by any stadard

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dreadnought72

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Re: Rotating seven gun turrets?
« Reply #153 on: December 30, 2016, 08:12:30 PM »

... ten hours later ... I think you've stunned the naysayers!  %%

Meanwhile, collision avoidance is leaping to mind. Or sailing a convoy using one master vessel.

All do-able!

Andy
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Bob K

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Re: Rotating seven gun turrets?
« Reply #154 on: December 30, 2016, 08:40:55 PM »

Awesome Andy  :-))  Can't wait to hear details, but I know you still have a lot of testing and debugging to do.  It sounds like you are making excellent progress though  O0

Not sure about collision avoidance etc, but we don't want to ram the target vessel !!!!
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Re: Rotating seven gun turrets?
« Reply #155 on: December 30, 2016, 09:35:38 PM »


It tends to knock my suggestion  (in post 2)  of a rubber band into a cocked hat  %%    %%

All very clever stuff and an interesting article

Cheers

ken
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RAAArtyGunner

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Re: Rotating seven gun turrets?
« Reply #156 on: December 31, 2016, 02:57:51 AM »

Radar - like this?

https://www.youtube.com/watch?v=rh6UxpzHlJI

NB Pretty amazing development board by any stadard

Very realistic. :-)) :-))
In some situations the speed is increased when searching a smaller arc, namely when the target has been identified/acquired.

Interesting to hear commentary from any Naval gunners if any on the forum???
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derekwarner

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Re: Rotating seven gun turrets?
« Reply #157 on: December 31, 2016, 05:42:48 AM »

RAAArty....whilst I am sitting on the sideline watching progress, however having technical training and experience in gun and director 'fire control systems' I can confirm

On a warship at sea, when the FCS director dome locks onto a target, the director body physically moves .......if we can imagine the director dome is locked onto the target, the dome does not move....it is locked

So when the vessel pitches or rolls, the directors electro hydraulic system is compensating for the movement of the vessel

In slow motion, the director is sending a continuously varying set of co-ordinates to the gun mount fire control system to compensate for the pitch & roll of the vessel

Gun mount director fire control systems were in their absolute infancy in design and use on Dreadnaught vessels.....the scholars suggest approximately only 3% of Capital ordinance firings controlled by director systems in the Battle of Jutland accurately found their mark

On modern day vessels [5000 tonnes] in a war training exercise, the barrel of a 125 mm quick fire gun mount can be visually seen to appear 'hunting in both train and elevation'. This naturally is that the dome of the director and the barrel of the mount are absolutely locked on the target despite the vessels pitch & roll

I doubt if any similar visual scenario would have been evident with the slower movement of 12" or 14" guns on Dreadnaught vessels of 25000 tonnes

Derek
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raflaunches

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Re: Rotating seven gun turrets?
« Reply #158 on: December 31, 2016, 08:51:52 AM »

From what I've read so far on the subject of Dreadnought era gunnery and firing the fire control director tower housed the optical sights and possibly the mechanical range finder computer (Dreyer Table). In that era the director didn't directly control the turrets like they do today but gave the range to the turret gun crew who then moved, elevated or traversed the turret in to the firing position. Essentially they were lookouts with a radio telling the turret crews where to aim. So whilst it looks pretty for all the turrets to move as one it may not always be true.
I stand be corrected and learn but that was how Dreadnought's turrets worked from what I've read.
However I'm not a buzz kill and find this thread fascinating and it would look spectacular working on Agincourt or any other warship model. Keep up the good work. :-))
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Bob K

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Re: Rotating seven gun turrets?
« Reply #159 on: December 31, 2016, 09:15:56 AM »

I still find it amazing that capital ships of that era could hit anything at all with their voice commands plus  pointers and graduated scales inside the turrets.  Agincourt did not even have a Dreyer Table at Jutland, she fired 144 shells yet no recorded hits.  Firing was probably limited to 'top of the roll'.  Thinking was to a degree still Nelson era too, close battle lines to 6,000 yards and blast away.  In practice the range far exceeded this where meaningful accuracy was beyond the limits of equipment available.  British hits were only 2.7%.
Gun elevations seemed to vary greatly, almost at random.  Maybe due to recoil effects and the mechanics of loading?

It is just when you look at a Challenger 2 tank firing accurately whist travelling at speed over rough terrain . . .
No comparison
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malcolmfrary

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Re: Rotating seven gun turrets?
« Reply #160 on: December 31, 2016, 09:50:06 AM »

Radar - like this?

https://www.youtube.com/watch?v=rh6UxpzHlJI

NB Pretty amazing development board by any stadard
Streets in front of what I imagined - I was thinking that a rotating directional aerial inside the superstructure could "find" a transmitting target carried by either a target ship or somebody on the bank (sort of doing the lookout job) then the arduino could tell the director/rangefinder where to point then the turrets.  It is 1916 technology that is trying to be simulated as a special effect on a model, so really, as with most of the things we do, it is an effect rather than an actual event that is wanted.
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #161 on: December 31, 2016, 10:11:31 AM »

Quite right about the rather rudimentary director control methods in use at Jutland. The Gunnery team in the foretop would transmit the range and elevation to the turrets using electrical pointers. The turret crews would line up on those pointers and I think the guns could then be fired from the foretop, as Bob says, 'on the top of the roll' when the ship was level. Gunnery officers hated course changes as it meant they had to re lay the guns and start again just as they were 'getting their eye in'.

There is one other thing I don't think has been mentioned and that is, while the guns could be loaded on any bearing and any any elevation, in practice loading at elevation was slow as the rammers had to push the shell and cordite bags uphill so a common practice was that after the gun had fired it was lowered almost to the horizontal for loading and then re elevated. This process was much quicker. You can see the guns dipping after firing in many films of gunnery exercises.

NB: I'm not suggesting we should go so far as to emulate this though!

Colin
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plastic

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Re: Rotating seven gun turrets?
« Reply #162 on: December 31, 2016, 04:03:56 PM »

It would be very simple to build 2 types of module smaller than a matchbox with a pulsing I/R LED to drop onto the decks of 'goodies & baddies'. to designate ships.

Choose 2 separate frequencies for friend or foe and have the detector on the warship look for, lock onto and aim the guns at.

A simple binocular detector that rotates until both detectors give the same o/p signal will give you the heading to the I/R source - and should stay locked regardless of movements of both ships.
If you have multiple ships, it would be interesting to watch the guns re-train on the next target when lock is lost on the first ship. The same detector could identify 'hits' from the other vessel if the guns had I/R LEDs and were pointing exactly towards it. If the detectors could differentiate more than 2 frequencies, a counter could decide when the ship has had too many hits and is out of commision. Game over.
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srcampb

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Re: Rotating seven gun turrets?
« Reply #163 on: December 31, 2016, 06:03:09 PM »


"It is 1916 technology that is trying to be simulated as a special effect on a model, so really, as with most of the things we do, it is an effect rather than an actual event that is wanted."


I fully agree, and can't wait for the January thread on development.. Thanks!!
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unbuiltnautilus

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Re: Rotating seven gun turrets?
« Reply #164 on: December 31, 2016, 06:39:02 PM »

Radar - like this?

https://www.youtube.com/watch?v=rh6UxpzHlJI

NB Pretty amazing development board by any stadard




Very impressive, although I feel that at our local lake, as you lower the model into the water, someone would nick your laptop :}
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dreadnought72

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Re: Rotating seven gun turrets?
« Reply #165 on: December 31, 2016, 08:44:29 PM »

I still find it amazing that capital ships of that era could hit anything at all ...


Me too, though I suppose it largely boils down to spotting splashes (over, under), adjusting, using a Dreyer table, and following it up with the sheer volume of fire. It's interesting that only 24 years later, that old Jutland veteran HMS Warspite manages a hit at around 26000 yards using radar: technology we're more attuned to, which (perhaps) makes successful gunnery more 'obvious' to us.


Andy
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derekwarner

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Re: Rotating seven gun turrets?
« Reply #167 on: December 31, 2016, 09:55:33 PM »

As Colin notes.......

'so a common practice was that after the gun had fired it was lowered almost to the horizontal for loading and then re elevated'

This is correct as loading was limited to a few degrees +/- of horizontal as the axis of rammer assembly is fixed within the gun mount....

...'and I think the guns could then be fired from the foretop',.....well the Order to fire was given by the Senior Weapons officer in the Fire Control unit in a bunker down below in the vessel....this Order was relayed to the individual gun Captain in each mount [who only after confirmation of train and elevation bearings were established] relayed the Order to the Firing Officer ...& finally to a Weapons Seaman rating who moved a lever & pressed a button

All of this voice communication in each mount was relayed back down to the Fire Control unit where exact references to train & elevation together with knowledge of each charge weight and projectile were 'mumbo jumbled' and then compared to the reported accuracy of fire.....however, 'the guns could only be fired by electro mechanical function in each mount'....

Would need to take a cut lunch before firing could commence....... Derek

 
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Bob K

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Re: Rotating seven gun turrets?
« Reply #168 on: December 31, 2016, 10:36:04 PM »

How the Arduino prototype looked in 1918.   (Dreyer Fire Control Table)

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Re: Rotating seven gun turrets?
« Reply #169 on: December 31, 2016, 10:59:52 PM »

I expected it to look more like Babbages Difference engine but in a metal case with knobs for input and dials for output. The Dreyer table looks like a 2D Plotter which may well be how it outputs information?
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C-3PO

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Re: Rotating seven gun turrets?
« Reply #170 on: January 01, 2017, 04:22:45 PM »


I have so far been pursuing a solution using servo's - whilst this has in the main been successful it does have some challenges to overcome.

When you track a target the servo movement can be "jittery" - this has nothing to do with the Arduino - simply the fact that you keep asking the servo to move to a new point as the boat changes orientation - even with smoothing I have not achieved an acceptable smooth movement yet - still options to exhaust - May have to use a PID controller

Another physical challenge is protecting your compass sensor from "magnetic interference" - anything else that's ferrous or has a magnetic field - the compass sensors are super, super sensitive and can smell a servo within 6-12 inches proximity

So I dusted off some stepper motors and gave them a blast but came up with a technical problem that I can't see the solution too without additional work (calibration each power on) - maybe there is an obvious solution.

The stepper motor has no "position feedback" mechanism. It simply steps X steps in either direction as and when it's told to. So whilst you could manually align several steppers at the start it's possible they may drift in alignment over time.

But take this scenario - power disconnects from Arduino when they (steppers) are not in "park" position - how do you tell them to go back to park? they have no idea where they are at power on?

Andy - do you have a solution for this one? - Have I missed the obvious? - wouldn't be the first time :)

Does this simply mean that you would have to "calibrate" the system each time you "power on" so they know where home is?

I think driving 7 steppers from one Arduino could be interesting...

So as always one step forward, three quarters back

*-*-*-* Happy New Year *-*-*-*

C-3PO
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Martin [Admin]

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Re: Rotating seven gun turrets?
« Reply #171 on: January 01, 2017, 04:35:38 PM »


What sort of price are small stepper motors?
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C-3PO

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Re: Rotating seven gun turrets?
« Reply #172 on: January 01, 2017, 04:40:32 PM »

Prices vary depending where they come from

approx <10 for 4

http://www.ebay.co.uk/itm/401107384327

C-3PO
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Martin [Admin]

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Re: Rotating seven gun turrets?
« Reply #173 on: January 01, 2017, 04:49:51 PM »


OK, cheap enough!   :-))

Could you use a micro switch to register a 'home' position?
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Bob K

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Re: Rotating seven gun turrets?
« Reply #174 on: January 01, 2017, 05:00:45 PM »

I think driving 7 steppers from one Arduino could be interesting...

C-3PO

C-3PO.  In my case ( 7 turrets ) there will of necessity be two systems, one for each split hull half, with a separate Rx in each half, and I suppose separate compasses too.  ie:  No servo leads to keep disconnecting between hulls. 

As I suspected the solution is not as easy to achieve as previously supposed.  Sorry to cause grief.

Bob K
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