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Author Topic: T.A.R.G.E.T - Rotating Seven gun turrets?  (Read 42086 times)

Bob K

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Re: Rotating seven gun turrets?
« Reply #50 on: December 25, 2016, 08:35:11 AM »

Morning all.  Merry Christmas  O0
Just slipped into the workshop for a puff, and put the computer on.

Thank you all for the super suggestions and technical information.
Normal Home Waters for me is Black Park Lake which is around 250 meters wide, and much longer though we don't use the 'Island' end.  So plenty of room.  However much more than 10 M from the side any on-board movements become less visible.  Agincourt was not known for her turning circle so I will do my usual and make the rudder a lot larger, aided by proportional control of the outer props.  With a model perceived movement and speed is rarely true scale anyway, but what 'looks' right.  She will also be used on waters such as Wicksteed where an enhanced turning circle is essential.
Guns will train on an imaginary target, not a scale 20,000 yards (almost full lake width).  I will need to train a full 90 degrees at least for a full broadside.  My aim is for a reasonable perceived turret movement, slowed rotation, not all exactly together in a modern Ballet synchronisation.

Any Adruino solution I would need some serious assistance on, as I said before.  Otherwise I will go for geared drives and maybe three servo slowers to have slightly different visible rotation speeds.
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Re: Rotating seven gun turrets?
« Reply #51 on: December 25, 2016, 03:02:34 PM »

Arduino, or Raspberry Pi will control up to 12 servos (and/or esc ) either individually, or in groups, using one of these ......    http://www.hobbytronics.co.uk/raspberry-pi/servo-pro-12ch

Full setup details on the page.
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Re: Rotating seven gun turrets?
« Reply #52 on: December 25, 2016, 08:41:48 PM »

Bob,

Lots of great info and suggestions here!

Can I suggest for now that you forget any technical solutions and simply specify what functionality you would like to have assuming that technology can support your wish list.

Some things you may want to think of to start to create your shopping list/functionality specification:

  • How would you like to trigger the movement of the gun turret(s)?
  • Would you like to dynamically pick 1 or more turrets and get them to move 90 degrees?
  • Would you like to be able to repeat this with guns that are still in their home position, even as previously selected guns are still deploying?
  • Do you want to tell the turret(s) selected to move to port or starboard?
  • Do you want to dynamically choose the deployment speed (say slow, medium, fast)
  • How would you like to trigger turrets to move back to home position?
  • Do you want to make guns fire (flash an LED, play a sound file, release smoke, move the guns to simulate recoil) ?
  • Guns can only fire when stationary in their 90 degree deployed position?
Some of this scale functionality may not replicate what happens/happened on the real ship(s) - but this is your list so as far as I am concerned there are no rights and wrongs!
Once you have your "dream" list of functionality it will perhaps help determine which technology route can best deliver a solution.
I do understand that the KISS servo morph route may be attractive - however if you are up for it with help you have the opportunity to chart some new waters!
Regards
Jonathan
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #53 on: December 25, 2016, 08:51:32 PM »

If you are busy steering the model around the pond then the less you have to do to micromanage the main armament the better! I would think it is best to emulate full size practice if possible. The captain cons the ship, the gunnery officer endeavours to keep as much of the main armament pointing at the designated target as possible. Don't try and simulate local turret control - that way madness lies... :o

Colin
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Re: Rotating seven gun turrets?
« Reply #54 on: December 25, 2016, 09:26:36 PM »

If you are busy steering the model around the pond then the less you have to do to micromanage the main armament the better! I would think it is best to emulate full size practice if possible. The captain cons the ship, the gunnery officer endeavours to keep as much of the main armament pointing at the designated target as possible. Don't try and simulate local turret control - that way madness lies... :o

Colin

If you go the microprocessor route you can designate the target bearing and then guns can keep their bearing to the target as the ship turns.  You just need to invest the time needed to meet your wishes.
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #55 on: December 25, 2016, 09:41:12 PM »

Exactly, that is what I said in my earlier post.

Colin
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Re: Rotating seven gun turrets?
« Reply #56 on: December 25, 2016, 09:55:25 PM »

If you are busy steering the model around the pond then the less you have to do to micromanage the main armament the better! I would think it is best to emulate full size practice if possible. The captain cons the ship, the gunnery officer endeavours to keep as much of the main armament pointing at the designated target as possible. Don't try and simulate local turret control - that way madness lies... :o

Colin
Hmmm - this may well be the case but it does pre-judge the effectiveness of the interface between the human and the control system  - for example this interface could be voice commands which mean you do not need to take your eyes off the vessel, I can think of other options which could work effectively.

My intention was not to limit the shopping/ functionlity wish list, clearly aspects of the functionality may be discarded as impractical, impossible to support with technology or just plain over the top etc. There is nothing worse than - "I was going to mention but ...."

One aspect to consider maybe "Exhibition mode" - that delivers specific functionality/movement of turrets when model static on show....

If this type of solution is to exist there needs to be a "blueprint" to work from which was the main reason for my post.

Regards
Jonathan
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #57 on: December 25, 2016, 10:13:31 PM »

Yes you are quite right Jonathan, before you start you do need to have a clear specification of the functionality you wish to achieve and how you intend to use it. The absence of this is the main reason why so many computer based systems ultimately fail. That and the inability of the commissioning agency to refrain from constantly changing the spec as the project proceeds. The other common failing that the armed forces seem to fall into is over specifying so that what they want is not necessarily what they actually need which might be rather simpler. TBH I cannot think why you might want to have different control inputs for individual turrets unless you intend to engage more than one target simultaneously which would have been very unusual, even in WW2.

In this case I think that the overview objective, as stated above, is for the main armament to follow the target irrespective of the changing heading of the ship which is what I tried to briefly specify in one of my earlier posts.

Having worked out the basics of how that might be done then it is possible to look at refinements such as being able to provide for adjusting the rate of training of the turrets so that it looks right and to interface with a a servo or motor that gives a smooth rather than jerky movement. As you say, at the TX end, the operator might have alternatives by which the desired target bearing could be input. A verbal command based on the number of degrees away from true North for example.

As will be seen from this topic, there is a natural tendency to focus on detail before looking at the overall requirement and identifying potential problem areas which in the case of Agincourt include the geometry issues associated with the various turrets starting out in different alignments from rest. This really does complicate any electro mechanical solution but should be very simple to solve if each turret has its own control module.

Colin
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Re: Rotating seven gun turrets?
« Reply #58 on: December 25, 2016, 10:36:33 PM »

Colin,

I note that your interest "piqued" regarding Arduino. I am sure you will find it quite easy to make rapid progress with microprocessors, especially with your previous experience in programming and the logical approach to solutions that brings.

My starter for 10 wish list/suggestion regarding individual/groups of turrets movement may have been a red herring!

The start "home" point of each turret is simply overcome as you infer - you simply have a "home position" value defined for each servo in the program.

If going the servo route (ignoring for the moment a ship of 2 halves) the only control unit would be a single Arduino with servo's plugged into it in a similar fashion to a radio RX.

Regarding "jerkiness" of servo movement this is definatley an issue with Arduino PWM signals - the jitter can be quite a problem. There are work arounds/solutions but the programming can become pretty scary and like most things also has some consequences. However with simple and additional cheap hardware ( one option Kinmel has detailed) there are solutions to this which in themselves bring multiple benefits.

Slowing the servo movement & soft start/stop is easily achieved.

One thing I wondered about - what would happen when the ship turns at the end of a boating lake? - would the guns simply need to track to the opposite side of the boat?

There is also a risk of taking this all to seriously - the fun aspect can't be lost!!

I have escaped Chrimbo TV - duty beckons - I just hope Strictly and Bake Off have been and gone!

Regards
Jonathan
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #59 on: December 25, 2016, 11:15:51 PM »

Jonathan,

I have been speed scanning the Arduino book and while I have not absorbed the detail, I can follow most of the logic. The programming itself looks relatively straightforward although the syntax is different to what I was used to (I wrote a commitment accounting and property management system in Foxpro). The interfacing with the external inputs and outputs is something new as I only had to worry about keyboards, screens and printers!

Can I pick up on two points in your last post?

Firstly you say that one Arduino board could control the seven servos needed to operate the turrets but how do you allow for the fact that in order to zero in on a selected bearing, four turrets would need to turn in one direction and the other three in the opposite one? One set of turrets might only have to say, move 30 degrees to bear on the target but the others would need to turn the reciprocal which would be a much greater movement. In fact several of the turrets would need to turn by different amounts to line up together. This is why I assumed that each turret would need its own decoding unit to compare where it was with where it needed to be.

Secondly, re your point about what happens when the model gets to the end of the lake. This is essentially the same as what happened when Beatty's forces ran into the High Seas Fleet at Jutland. Initially all the turrets were bearing to port but Beatty had to make a 180 degree turn so as the ships turned round all the turrets had to swing back through the centreline and bear on the opposite beam.

I can't see any real need to dynamically control the speed of the turret rotation, in reality they would all be around the same as makes no difference but I can see that it would be necessary to set a default speed to be able to fine tune what looks 'right' on the model. Presumably a variable can take care of that if controlled by the Arduino board.

With regard to the jitter you describe, assuming that the actual servo is capable of smooth movement, as most are, then would it be possible to deal with the speed adjustment mechanically, using gears to achieve the desired rate of turn with full voltage applied to the servo. Then, could the Arduino board simply apply full power to the servo until it reached the stipulated bearing? This would obviously entail a 'hard stop' but if the turrets are turning relatively slowly anyway it might be OK. Or, if as you say soft starts and stops can be accommodated, then could the board apply full power to the servo until within perhaps 5 degrees of the required bearing and then go into soft stop mode? I think it would be something of a suck it and see situation for which a test turret mechanism would need to be constructed.

We learn something new every day!

Colin
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Re: Rotating seven gun turrets?
« Reply #60 on: December 26, 2016, 12:00:52 AM »

Colin,

The Arduino Uno has several PWM ( Pulse Width Modulation - a square wave signal) pin connections.  Hardware wise it has only 6 PWM pins - there are ways to use other pins as PWM connections.

Each PWM pin can be set to a specific value (ms) - and therefore set the rotation/position of individual servos. You may well need to have an "offset" for each individual servo to make them equal to their colleagues - tracking wise you would be able to get them to all head in the same direction (may need some clever adjusting)

The jitter is caused by a slight timing difference( due to interrupts in the Arduino chip) in the PWM square wave signal that causes the servo to move very small amounts as it's PWM varies minutely.

I think there maybe some confusion regarding how the servo works - it has nothing to do with the voltage changing - it is due to the width of the pulse (PWM) - typically 1.5ms square wave being the centre position of the servo - 1ms and 2ms the full travel PWM's

see this link http://www.seattlerobotics.org/guide/servos.html or https://www.youtube.com/watch?v=EpB53YZc3rs

I could not agree more with the learning comment - one of the reasons I play with Arduino's and the like is to keep my mind active...

Regards
Jonathan
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Bob K

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Re: Rotating seven gun turrets?
« Reply #61 on: December 26, 2016, 01:01:14 AM »

As much as I admire everyone's technical enthusiasm here, there are some practical limitations in a model on lake scenario.  Before getting into constant GPS bearing issues, our lake is 'only' 250 m wide (around 100 ship lengths ) and well before you get a third of the way across turret positions will be all but invisible from shore.  Rather different to displaying a model tank a few yards away.

The second issue is having two independent halves is a practical must-have. I have a distinct aversion to unplugging connectors, except for maintenance, especially servo leads.  It is asking for reliability problems.  I tend to charge batteries via on-board charging sockets with a C/O switch. 

  • What I would like to do is train the turrets to a bearing relative to the centreline, via a rotary Tx control.
  • The 3 turrets in the fore half all point the same way.  Aft one faces this way, with three in the opposite direction.
  • I could turn the rotary dial slowly, but it would be nice to have a slowed rate built in.
  • Slightly different rate of turns a preference, but not absolutely essential.
  • Soft start and stop might add realism, but visual effect minimal.

Elevating the barrels are best effected mechanically by internal ramps and springs.
Gun fire sound / LED's a separate channel, via a Tx switch.

Hopefully the above wish list is not too complicated.

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Bob K

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Re: Rotating seven gun turrets?
« Reply #62 on: December 26, 2016, 09:10:05 AM »

Some further thoughts, after carefully reading and viewing all the various links provided.
One of the biggest problems in my mind is when getting the forward facing guns to point, say, 30' to port, the rear facing guns will have to traverse 150' in the opposite direction.  That alone leans towards internal calculation as against say a 5 servo controller which although can set individual turrets to reverse direction is not able to calculate how much by.
A fixed aim point of 90' abeam would avoid this, but be of limited use.

Traversing more than 160' total would risk servo judder, even in computer versions, but although work-arounds exist they appear to complicate programming.  Ideally a 270' servo would make physical movement simpler than gear trains. ie:  have the turret axis mounted direct over the servo axis.

The more I read online the more I am thinking that some form of computerised device is needed in each half.

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Re: Rotating seven gun turrets?
« Reply #63 on: December 26, 2016, 09:55:57 AM »

Bob,

The calculations bit re a turret moving is simple.

Even for <£10 you are getting an Arduino capable of 16 million clock cycles a second - a few calculations don't even make it break into sweat.

Re the servo jitter - assuming the servo can physically move without jitter to it's end points then a simple additional chip <£5 will eliminate the microprocessor causing any jitter

The 2 halves issue does need some thinking about to make the most useable solution. Clearly if 2 control units involved they will need to receive instructions from you main TX to do their thing!

It would be possible to re-transmit a signal from one half to the other on-board - perhaps via Infrared if a Infrared TX/RX sensor could be placed above deck in line of sight with each other - one in each half- some of the sensors are no bigger than a typical LED - this way only one of the units would need to be directly connect to the RC receiver.

What make and model of transmitter are you thinking of using?

I appreciate that the unknown subject of the microprocessor can be daunting - with help, and as time goes on you will be amazed at how simple it can be

One aspect of this that it worth pointing out is that if you compare pasting text into a Microsoft Word document, amending a character or two and then hitting save - this is no different in concept to programming an Arduino. So if people help you they would send you the program text via email.

1. Text is entered into text editor (Arduino IDE) which could simply be pasted text supplied to you from an email
2. Hit save to save the doc
3. Hit upload - and the program is sent to the Arduino down a USB cable in a few seconds

Job done

C-3PO

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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #64 on: December 26, 2016, 10:01:36 AM »

Bob, I was going to apologise for hijacking your topic a bit but you have highlighted an issue which has plagued model warship builders for decades! From what Jonathan has said and from my initial reading of my Arduino book it is evident that the various components and techniques already exist to put together a sophisticated main armament control system. It just needs someone to put in the development work to make it all come together. But in doing so the aim should be to develop a generic module which can then be programmed with the variables needed for the particular application it will be used for such as maximum traverse angles, rotational speed etc. It could then be very simply adapted to any situation, even dreadnoughts with wing turrets.

In your case I don't think that splittting the hull will be an issue. It is possible to bind two RXs to one TX using the 2.4GHz system so both receivers would be getting exactly the same signal from the TX. So each hull half can have its own independent system

In your earlier post you mentioned a rotary control, but, as you have realised, if you simply wire up all the servos together then pointing the forward facing turrets 30 degrees off the starboard bow will simply cause the aft facing ones to point 30 degrees off the port quarter. Reversing the servos for the after facing turrets would just mean that they pointed 30 degrees off the starboard quarter instead. This is why I suggested that in practice a simple electro mechanical system will only give three positions with the guns facing in the correct direction, 90 degrees on each beam and on the centreline. For this you only need a single push button to cycle through the three positions. The turret servos would need to be geared down to an acceptable visual rotational rate and you could vary this slightly for individual turrets by slightly altering the gear ratios. All this would probably work OK eventually but would obviously not be as good as a fully computerised system with all its extra features.

Rock and a hard place perhaps?

The place to start, as always, must be to prepare a generic specification for the developer to work to so perhaps we could try and agree a list of desirable features as a basis for this.

Colin
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Bob K

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Re: Rotating seven gun turrets?
« Reply #65 on: December 26, 2016, 10:33:35 AM »

Bob, I was going to apologise for hijacking your topic a bit . . .

Not in the least Colin.  Your detailed responses have been most interesting and relevant.

Yes, I use a 2.4GHz Planet system for everything that does not submerge or semi-submerge.
Maybe a system that has a number of channels for forward facing guns, plus channels for rear facing guns, could become a generic for a wide variety or turret warships.  Two units, programed identically, could thus be used in either half of the hull.  With suitable calculations matched bearings totalling 270' per turret should be possible.

I had put my wish list in an earlier post.  Anything beyond this a bonus.
This is a silly sized build, but at least internal space is no object  {-)

Thanks again.   Bob K
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Re: Rotating seven gun turrets?
« Reply #66 on: December 26, 2016, 10:34:13 AM »

Bob, Colin,

This may shed some light on the simplicity (Arduino PWM & Servos)

https://www.youtube.com/watch?v=GzTPa0UL6vo

C-3PO
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #67 on: December 26, 2016, 10:57:59 AM »

Bob, if I have grasped the possibilities right then it should be possible to do the whole thing with just one rotary channel on the transmitter!

I will have a shot at a basic spec.

Colin
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Re: Rotating seven gun turrets?
« Reply #68 on: December 26, 2016, 11:26:06 AM »

Bob/Colin,

Unless I am mistaken the Planet TX does not have a rotary proportioanl encoder/Pot ("knob"). - it might be possibel to add one.

It would be possible to use a resistor ladder within the TX on one of the proportional channels to add a bank of buttons to the TX allowing events/functions top be triggered

Eg Button for Stop/All guns to 90 degrees port / all guns to 90 degress starboard / all guns "home" position.

Or you could use one of the proportional stick to do the same

Stick full up long > 1 second - All guns 90 degree port
Stick down long > 1 second - all guns 90 degree startboard
Stick down short <1 second  - xxx
Stick up short < 1 second - yyy

Stick half up short <1 second - all stop

The Arduino on the boat can work out what signal has been sent a then invoke the relevant function

Have fun with the spec....

PS - another great point of this style of development is that there are several people on this forum that know and love (as well as hate) Arduino's

For example Tim "tsenecal" has created  Nautic decoders for Robbe F14/F16 and the like using an Arduino for the cost of <£10 - compare that to the price of the original kit!

Have fun

C-3PO
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Bob K

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Re: Rotating seven gun turrets?
« Reply #69 on: December 26, 2016, 11:34:54 AM »

The planet T7 has a rotary control for channel 6, plus a three position switch for channel 7.
Also a slow-rate or normal-rate retract/flap switch on channel 5.

It would be nice to set an angle for all guns to point to
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #70 on: December 26, 2016, 11:48:09 AM »

I will throw the draft spec below into the ring for comment, hopefully it should show up any inherent problems. The operator does need to know roughly where the cardinal points of the compass are from where they are standing but that shouldn't be a problem. North should line up with the mid travel point of the rotary switch.

Colin

 Model Warship Turret Control Basic Specification
 
Objective:
To enable the turrets on a model warship to dynamically bear on an absolute target bearing remotely specified and constantly changeable by the model operator.
 
TX Input
The operator should be able to specify and alter an absolute target bearing expressed in degrees from true north using a rotary control on the TX
 
Model Onboard Components
GPS or Electronic Compass capable of determining and outputting the number of degrees by which the modelís heading deviates from true north.
 
Control board capable of comparing the heading of the vessel with the specified target bearing from the TX and outputting the difference as degrees based on 0 degrees being the bow of the model  and 180 degrees the stern. (0 - 359 degrees range)
 
A servo module for each turret which is pre programmed with the allowable maximum traverse in degrees each side of the centreline of the model and also the desired rotational speed of the individual turret.
 
Means of Operation
The operator specifies the absolute target bearing in terms of compass degrees and transmits it to the model.
 
The model compares the transmitted bearing with the modelís actual heading dynamically and transmits the difference to each turret module which informs the turret module of the bearing of the target relative to the current axis (heading) of the model.
 
Each turret module examines the relative bearing to the target and checks to see if it is within the pre programmed traverse limits for that turret. If so then the turret will traverse until it matches the received bearing and will continue to follow it while it is within the turretís limits of traverse. This might entail moving in either direction depending upon how the model is changing course. For example a turret may need to swing right round to the opposite beam to stay on target. This can all be done in the module programming.
Optional: The turret module may feature programmed soft start/stop for extra realism.
 
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Re: Rotating seven gun turrets?
« Reply #71 on: December 26, 2016, 06:13:58 PM »

hi there Bob are you still with this topic :-)

As I have stated previously the mention of electronics sometimes puts people off and I think this topic might put a few off.  Basically all that is required is to train the guns on an imaginary point on the lake where all the guns point at the same area.  They don't have to be clinically correct to Royal Naval standards and to the degree which I think we are 'aiming' for in this topic.   Having said that though the old grey matter went into remembering mode - because - years ago I built an electrical circuit called a Servodriver.

It is based on an IC chip numbered IC741 - way out of date now - but the principle was to mimic the pre-set range dial which was independent - originally built for a remote controlled radio aerial.   I could preset/move the aerial around to obtain different signals.   Bearing in mind the aerial was mounted on the house roof (I was using this for listening to amateur radio).

My thinking is under say, the main one turret, which is going to become the main turret, you have the main select pot of variable resistance and also this main drive gun was driven by a servo as well which was controlled by the handset.  Basically it is the same as I had suggested earlier on, but, instead of using servos you use geared motors on the rest of the turrets which would mimic the movement on your first turrets.

Maybe a simpler system to construct and understand.

Last but not least, could you not keep the hull as one and fit a roof rack to your car?  You could then place the hull on the roof rack and make the whole deck / superstructure to split into two and fit inside the car?

John
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unbuiltnautilus

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Re: Rotating seven gun turrets?
« Reply #72 on: December 26, 2016, 06:48:52 PM »

Almost all of our 8 foot plus models are now built to at least split in half. Our 6 foot battleships are currently two built in one piece and two split in half. We still have one 102" battleship in one piece. It is a two man job to put it on the roof. It makes life easier generally if you can divide the model up, for both transport and storage.
The only disadvantage we came across was this, more trips to get the model in the car, and more trips from the car to the lake! Build a trolley to take everything in one move.
I like the idea of the master ( A ) turret, controlling everything else, however, I am now most interested in the electronic solution. Some of the suggestions are possibly straying into realms of sophistication not needed on a model boat. However with a little additional technology, and a couple more models with similar electronic fits, a proper sea battle could be staged. Including IR firing, registering hits etc..let us walk before we can run first.
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Colin Bishop

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Re: Rotating seven gun turrets?
« Reply #73 on: December 26, 2016, 06:58:49 PM »

I think you have glossed over a bit there John! The first turret could be used to control turrets 2,3 & 5 but how would you construct a linkage to turrets 4,6 & 7 which start off facing in the opposite direction and would need to rotate by an entirely different amount for any given required bearing?

Colin
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Bob K

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Re: Rotating seven gun turrets?
« Reply #74 on: December 26, 2016, 07:42:35 PM »

There is another restriction to roof racks.  A height bar over the entrance to our lake car park.  I have seen it remove bicycles most dramatically.  Definitely a two man lift involved, then getting it to the water.  Halves are easier to manage.

A little side step here.  I hope we are not being carried away with having seven turrets.  Try thinking of four turrets on a WW2 destroyer, facing both fore and aft.  Even HMS Devastation with just two.  Crack Devastation and you have solved the problem, as after that it is just more of the same.  I have seen it done so there must be existing solutions.
I have seen examples at Wicksteed.  The Portsmouth Display team run gun battles with turning turrets.  Whether this is done with a single control I have no idea though.

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