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Author Topic: JUPITER, A Caledonian MacBrayne Ferry....My new project.  (Read 119647 times)

cjcj121

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #25 on: August 12, 2013, 10:21:38 PM »

Interesting model subject . Gonna keep my eye on this  :-))
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Sandy

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #26 on: August 13, 2013, 04:39:02 PM »

I saw Andrew today here at the BBC and he mentioned this thread.
 
Nice to see this being built. I was on the 'Isle of Arran' (Calmac's stand by ferry) some months ago fixing their server and the Saturn was moored alongside at Rosneath. I guess she will end her days there.
 
I am assuming, being a Model Steamer Club boat, she will be 48th scale?
 
All the best
Sandy
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #27 on: August 13, 2013, 05:03:27 PM »

Hi sandy.........I think Andrew has built the plug to around 1:45 scale so I won't be changing it........I have the plans full size to hull so will be following them for everything.
think we know each other from Shipsnostalgia if I'm not mistaken.
 
Yes, went to Rosneath last day of our hols last Friday, and twisted the arm of the Operations Manager at Calmac to allow me to take some photos of her from the Jetty, on the condition that I didn't publish photos of her......"I went on a guided tour" in absentium of the owner of the Rosneath marina so as I promised, I'll keep the photos of Saturn private, sorry.
 
neil (nhp651)
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Sparky

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #28 on: August 13, 2013, 11:11:15 PM »

Neil -- I'm so sorry to hear that you've been b------d about by some selfish individual,
you were only trying to do your best for them, lower the stress levels by continuing to
build your models to your usual high standard !, :-)) :-))  and keep the photos coming !
 
(after reading your earlier post)
 
Vic.         ok2
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #29 on: August 13, 2013, 11:17:52 PM »

Cheers Vic..............it'll be a week or so before |I get down to the ferry in earnest as I am re fitting some grab lines to one of my older lifeboats at the moment ready for a few sails this summer ( what's left of it..........so the Jupiter will wait a few days.
neil.
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Pioneer

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #30 on: August 14, 2013, 10:33:20 AM »

Hi Neil and Sandy
 
The reason the hull is the scale it is was driven by the size of the Graupner Voith propulsion units. At 1/48 scale the hull would have been a little too small to fit them in. The difference in scale won't be that noticeable on the water with other models. The stern unit will still be fun to fit though....... but that's another story....... {-) 
 
Regards to you both
 
Andrew
   
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Sandy

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #31 on: August 14, 2013, 10:58:23 AM »

Hi Neil and Andrew,
 
My plan with the 'Sound of Shuna' was to have a strategically placed pair of containers or trucks on the car deck...  :-)
 
All the best
Sandy
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #32 on: August 14, 2013, 11:28:44 AM »

Just wading in, here.

Remember those camera pedestals you saw? They're maybe the answer to "how" to operate twin VSs.

In normal camera mode the peds are in "crab": all wheels turn together, controlled by the steering ring. The ped moves ariound the floor without changing its heading.
In not normal mode, the ped can be put into "steer" which locks two sets of the three wheels, and the steering ring controls the third set, allowing you to just change the heading.

So what if ...

You use two channels (X/Y) to control the direction of thrust of both units, and one switch to allow you to enter crab or steer.

In steer mode (the default for sailing around the lake) the forward and aft VSs are inverse linked to the steering input - if the forward one thrusts left, the aft one thrusts right.

In crab mode (the best for parking up and setting off) the steering input is common to the forward and aft VSs - both thrust left or right.

There's a way to do this with a home-brewed mixer, taking input from the receiver and pumping out whatever PWMs are required for control.

Andy (ex-BBC cameraman, who lives near Glasgow  %) )
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #33 on: August 14, 2013, 12:27:03 PM »

sorry Andy.......not being technically minded, you lost me on the first sentence.
 
neil.
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #34 on: August 15, 2013, 12:16:07 AM »

I'll try again!  :embarrassed:

For all your control needs, you only require two channels (that's one x/y stick) and a switch. Here's how it could be made to work (the following feels "intuitive"):

The switch allows you to select "crab" or "steer".

"Crab" moves the hull around without changing the hull's heading. Left/right, forward/back. And any angle inbetween. In this mode, the VSs do the same thing. The angle of the stick (measured from vertical = forward) determines the angle the hull will move, while the distance the stick is from the central position determines how much thrust to apply.

"Steer" drives the boat as normal. Forward/backward thrust depends on the stick's "y" displacement, while the "x" displacement adds side thrust, acting in opposite directions on the two VSs. This would allow you to turn on a sixpence (stick centred on the y-axis, but not centred on the x-axis), and drive the boat in a "rudder-like" manner.

So how would it work, technically?

On the boat the receiver decodes the switch state and the two channels - these two are output as "pulse width modulated" signals.

Using a microprocessor (arduino, pickaxe, raspberry pi - there's loads out there, around the 30 mark) you feed in the receiver output. Add some maths. And output pwm signals to your twin escs and the four servos that control the VS collectives. The programming required is not difficult, and if this approach (or something like it) is the route you'd like to take then I'd be happy to go into more detail on this side of things for you.

Andy, proud owner of a new Arduino - slated for turret control on a big, grey battleship some on the forum may recall.  O0



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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #35 on: August 15, 2013, 09:50:56 AM »

a little clearer andy........but could you draw me some diagrams please......might be able to understand it better if I have that help.
 
cheers, neil.
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #36 on: August 15, 2013, 11:24:48 AM »

Better than a diagram!

Try this wee app. It's written in Flash, so you'll need a non-Mac platform to try it out. If that link doesn't work, try this one.

There's a two-axis stick you can drag about, and a switch which can be clicked. The output of the controls are shown on the VSs - the black bar on each VS is the push from each. (And all in 8kb!)

In the real thing, as software is producing the outputs required for the escs and servos controlling the "collectives", this could be modded to best suit the requirements of the boat - such as " somewhat less" steering when in steer mode, to avoid it driving like a shopping trolley.

Andy


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Pioneer

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #37 on: August 15, 2013, 11:41:24 AM »

Now that's very clever!! :-))
They say a picture paints a thousand words! Brillaint Andy!
 
Regards
 
Andrew
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #38 on: August 15, 2013, 12:06:50 PM »

Many thanks!

Now then: is Neil convinced?!  ;)

Andy
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trawlerman

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #39 on: August 15, 2013, 12:29:56 PM »

Neil might not be convinced but I am, I,m convinced its going to be 6 months to build and about 20 years to get the drive to work. He,s going to be round our house every day saying how depressed he is...Cheer up Neil  ...Rod  :-))    :-))   %%   %%   {-)   {-)
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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #40 on: August 15, 2013, 02:25:36 PM »

Many thanks!

Now then: is Neil convinced?!  ;)

Andy
Yes andy........I'm convinced......however.........I have one problem with that in that I need both voiths to work together on forward and reverse but independently on the sideward movement, so that the boat can pirouette when needed, and those apps, don't show from one stick that I can do that
 
been pricing up an R16 tx/rx set today........ouch!!.......
 
as for you wodney............................yoo pyonker {-) {-) {-) {-) {-) {-) {-) {-) {-)
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #41 on: August 15, 2013, 03:36:08 PM »

It does - shove it into "steer" and move the stick left or right!  :-))

I've been tinkering with the maths in the meantime. Demo version #2 will be along shortly.

Andy
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #42 on: August 15, 2013, 03:58:17 PM »

ah yes...........I see now....it wouldn't work first time round on the steer.......was just using the crab switch, lol.........
 
brilliant................now how do I transfer that to electric wizardry.......please help. ta.
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #43 on: August 15, 2013, 04:20:38 PM »

Here's version 2.  And here, if that first link doesn't work for you.

Subtle differences: the full "square" of the stick movement is now enabled for the "crab" mode. That means you get 100% power only at full deflection, which would make for more accurate handling.

And in "steer" mode, I've toned down the steering at full ahead and full reverse - you get 20% "throw" when at full speed, compared to 100% when slow. This means less shopping trolley when motoring about, but full pirouette when stationary or at slow speed.

The thing is, once the basics are done, tweaking the specific constants in the programming allows for all sorts of mixer rates to best suit the vessel/operator/conditions.

As to transferring to electrical wizardry: an on-board microprocessor takes PWM inputs from the receiver. It crunches the info using a program*. It outputs PWM signals to the ESCs and four servos.

A board like the Arduino (~30) can handle the PWM inputs and outputs with a huge amount of accuracy and a high clock speed: you get a simple "single stick and switch" input which maximises all the functions of a twin VS on the boat, without having to master octopus-like levels of stick-control.  :-))

*programs need programmers. But programs are simply recipes written in a machine-friendly language. The examples I posted use a language called ActionScript, and took well under an hour to produce. I'm currently learning how to program the Arduino, and would be delighted to offer a hand when A/ I've mastered it, and B/ you're ready to go sail-by-wire.

Andy
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derekwarner

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #44 on: August 16, 2013, 01:03:36 AM »

A black art for me  ;D ....Question.......would a servo slow down be used on the control the rate of motion/change of direction to both drives? ......Derek
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #45 on: August 16, 2013, 01:59:48 AM »

No servo slow down required - it can be programmed into the software.

Andy
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #46 on: August 16, 2013, 06:57:19 PM »

well, I'm going to put that mind boggling part of the  project to one side for the moment whilst I think about it and get on with preparing the plug for moulding.
 
So, today I started by making the small plinths which will be moulded into and as part of the hull, and these were made from 6mm ply in the first instance.
 
They are actually not a scale part of the hull of the real ship but when moulded in, will give a flat base on which to put the flange ring of the Graupner VSPU , which in turn takes the actual unit.
 
also by lowering the position o the VPSU by giving it the extra depth it may alleviate the need to make a dummy piece of load where the motor part of the Vpsu could protrude through the deck.
 
But then again a modification from brushed to brushless motor purely for size might have to be thought of later, before the deck goes on............either that or a longer belt for belt drive.
 
I have also faired down the two skegs as shown on the plans for better water flow to the Vpsu's, and thus aiding better water flow.
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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #47 on: August 16, 2013, 07:12:38 PM »

Come on Neil VS PU each time or we will be more confused than you
when the build is doing basin trials %% %%
Unless VPSU means Very Posh Speed Unit :-))

Looking forward to the build.

Ned
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Neil

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #48 on: August 16, 2013, 08:22:13 PM »

whoops....sorry ned.....dyslexia rules, ko
 
must take more care %% %% %% %%
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dreadnought72

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Re: JUPITER, A Caledonian MacBrayne Ferry....My new project.
« Reply #49 on: August 16, 2013, 09:38:43 PM »

I hope you do go brushless. Not least because THAT's a black art to me - yet with VSs you only need "forward" ESCs, which might improve the "affordability".

Looking forward to seeing this build develop!

Andy
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