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Author Topic: Hasegawa Mikasa 1/350 Build  (Read 3772 times)

kikkari

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Hasegawa Mikasa 1/350 Build
« on: September 26, 2006, 08:47:18 PM »



Possibly not an ideal candidate to be made into an RC model but hopefully I can pull it off.  I'm going to build a cheaper Heller model first to make sure I can get the electrics right, but the Mikasa is what my heart is set on.

I have a collection of seven CDROM platter motors from which I plan to find a matched pair to use.   There are many variants of this kind of motor from Mitsumi, Mabuchi and others with various specs.  I plan to do some testing to match the motors up which I'll document here.

Has anyone had any experience with these motors?

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malcolmfrary

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Re: Hasegawa Mikasa 1/350 Build
« Reply #1 on: September 28, 2006, 04:19:31 PM »

I've used them (singly) in the Lindberg Classic series Tuna Clipper and the North Atlantic Trawler.  They are a good replacement for the servo motors because they have a sensible length of shaft to couple to, and work off the servo electronics.  Motors from different sources do perform differently.  The head drive motor is a siutable candidate in a small hull, but not all head drive motors are "normal" motors. 
In a small hull the best bet might be to use servo motors and control them with servo electronics (i.e. use servo's as parts mines).  The flint spring from a disposable lighter makes a good coupler to a servo motor spindle.
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kikkari

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Re: Hasegawa Mikasa 1/350 Build
« Reply #2 on: September 28, 2006, 09:24:09 PM »

Yes I see what your saying the platter motors have such a relatively large diameter that using three will present some problems fitting abreast in a warship hull.  I'm still keen to use them as I have a plentiful supply of them and I can easily get many more.  I think their large diameter leads them to be generally low rev'ing and smooth, I think they'll fit and I have dreamt up a mounting scheme that should work - a bit up in the air though a bit more thought required to bottom that out ;).

I have amassed a collection of the various motors from CDROMs I've put the tiny stepper motors to one side for special use later!...

I'm not a smoker myself, but shouldn't take too long to scrounge some flint springs - I'll try that tip - cheers.


Like a few other build threads that have inspired me I'll just blog my way through my build, hopefully some of it may be interesting to others and I encourage the more experienced to make suggestions or point out obvious mistakes that I am blundering towards ::).


My idea is to build up a small fleet of plastic models to sail at my local pond which is well sheltered on all sides by tall trees.  The first thing is to decide how I'm going to power these boats. I've just recently got interested in electronics and programming pic chips - so I'm wanting to build a custom speed controller as part of my build.   I've bought a Heller 1/700th scale model of the Gneisenau to prototype the electrics, it was cheap and has plenty of room inside for prototyping things like speedcontrollers.


I suppose the main physical constraints are size (it has to fit in the hull) and weight - the boat must float!  I plan to fill the hull with water up to the waterline and then weigh the water to give a rough idea of a max weight for the equipment  -is there an easier/better way?

I've chosen to use my existing LiPo packs, they're a powerful and lightweight powersource, using such light cells buys me some room to go a bit heavier elsewhere.
 

I've used two L298 motor drivers mounted side by side on a board to make a motor driver capable of driving 4 motors upto 50v with upto 2amps current per motor.  You can see the unit in the center of the hull in the picture.  It's a bit ugly but it's only a prototype and so far it seems to work well.  With independant control of four separate motors it would be suitable for a Yamato but I'll only use 3 of the 4 channels for the Gneisenau.  I'll build a controller with a single L298 for the two prop Mikasa.

The L298 is just a driver and needs a 5v PWM signal to provide the control to each motor. and that will be produced by the pic chip - I've recently moved to the 18F4331 chip as this has a motor controller capability that provides the generation of 8 PWM signals which is ideal for my twin L298 controller board as that needs 2 PWM signals for each of the four channels.

I've only had these new 18F4331 chips for a week and I'm still writing code...
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malcolmfrary

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Re: Hasegawa Mikasa 1/350 Build
« Reply #3 on: October 01, 2006, 07:51:28 PM »

Gauging the weight by filling with water to the required depth is the most practical way.  Guesiing what the deck + superstucture will weigh can be a problem.  With a warship you can always look in a copy of Janes Fighting Ships, but the figures given are almost always as issued by the government involved, and therefore a pack of lies to confuse potential enemies.  If you work to the calculated scale weight, you should always have a bit in hand.
The lighter flint spring (I dont smoke, either, but I do have a gas stove to light) is good for servo motors with their very short shaft, being a good push fit helped by being tapered at the end.  An alternative for CD platter motors is insulation from cable.  This rarely fits the propshaft, but can be a tight fit over a cotton bud tube.  You can get brass collars that fit over these to give a good fit and positive clamping to the prop shaft.
Incidentally, just one servo motor running off five cells gave my Heller Tirpitz a realistic turn of speed, using just one rather over-scale prop.
Best of luck with the electronicery.  I read somewhere that LiPo's dislike being wet, so some serious waterproofing might be in order.  Using the CD motors should help, as their diameter might push the inner end of the prop shaft tube above the water line.  Ifyou can arrange a continuous coaming around the superstructure, even better.
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kikkari

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Re: Hasegawa Mikasa 1/350 Build
« Reply #4 on: October 02, 2006, 01:17:32 PM »

I presume it's wise to stay as light as possible so you can trim the boat with lead, my intuition was to try and stay below 2/3rds the weight of the displaced water weight.  I hadn't overlooked the weight of the superstructure - although I have probably underestimated it - I'll give that a weigh as well and factor it in.

It didn't occur to me to look the displacement up in Janes.  My father was a merchant sea captain and I spent my youth at sea; we often went warship spotting in various places so I have a few good reference books including Janes, I'd like to see what was on those pages that have been deleted by the censor!? 

We had a particular interest in the Graf Spee and we went to Motevideo, I saw the Achilles off the coast of India in the 70s; I'm sure it was also with a Leander class cruiser but I guess it wasn't the Ajax.  Anyway - what I'm getting round to saying is that I remember we built a motorised Graf Spee (Tamiya kit?) and sailing it at the Harrowside boating pool on the prom in Blackpool quite some time ago now!  I remember that being a single prop setup and being very prone to letting water in, a single prop setup is probably the most sensible approach but I'm not about being sensible with this project!


This weekend I added a 433Mhz telemetry transmitter - tiny little thing, I hope it'll enable me to send pack voltage, throttle position, rpm and current drawn for each of the motors back to shore.  I'll use this hull to test motors  - I could build a static setup but this sounds more fun ::)

My plan to mount the deck and superstructure may not be too good, I'll post pictures when I get round to that bit.  I think the LiPos themselves will be OK getting wet, but some salty water shorting my home made controller could draw some dangerous current to which even my 10C packs might take extreme offense - I'll be sure to have my video camera to hand on the maiden...  :o
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malcolmfrary

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Re: Hasegawa Mikasa 1/350 Build
« Reply #5 on: October 02, 2006, 11:28:59 PM »

15,500 tons equates to about 13oz at 1/350 scale.  Thats about the same as my Lindberg Tuna boat.  I didn't use any miniature components in that, and powered it from 5 AAA cells.  Martin has some pictures hiding in the "Your Models" section. 
Stability should not be a problem as it is a battleship, therefore plenty of downstairs to not much upstairs.  I usually remove unwanted plastic that can't be seen from superstructure levels.  Just planting the deck will make for easy access, but makes for a very calm weather boat.  Battleships do tend to be very low in the water for their length, so waves can easily wash over.
Harrowside was a great lake for that size of model (motorised Airfix Iron Duke among others) but it is no more, having been lost under the new sea defences.  Shame.
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kikkari

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Re: Hasegawa Mikasa 1/350 Build
« Reply #6 on: October 03, 2006, 12:55:50 PM »

Quote
15,500 tons equates to about 13oz at 1/350 scale
I'm afraid tons and oz are foreign to me, 100cubic feet = ton and long and short tons have me reaching for the aspirin - metric tonnes, 1litre = 1 Kg are my thing!

Found your page in the your models bit - lots of detail in the write up there for me to look at - unfortunately the links to the pictures are messed up, I'd like to see the big versions of a few of those pictures (I guess I'll get to see the actual boats at some point too? :)).  I'll email admin and see if he minds redoing the links.

I plan to sail the plastic boats in Ashton Gardens in St Annes and the big rectangular boating/paddling pool on the prom near the rock gardens, quite a nice little venue the rectangular pool - it's filled  in the summer only usually though.  Both places are very very sheltered, I fly the ultra lightweight parkflyer rc planes so living in a place known for land yachts and kites I've grown pretty patient waiting for calm conditions.   I also have access to a hotel pool in the late evening early mornings (11pm - 2am) it's not very big but a good place to trim out a new boat I guess.

Yes - I can't remember being at Harrowside when it wasn't a little too windy but it was a decent sized boating pool, I can't complain though I have a few venues to go to within 2mile of where I live

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malcolmfrary

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Re: Hasegawa Mikasa 1/350 Build
« Reply #7 on: October 03, 2006, 02:39:21 PM »

13oz is about 370gm.
On a nice evening you can wander along to Fairhaven and catch us there.  We have the end of the lake boomed off near St Pauls Avenue - nice and sheltered, but salty water.  Beware of parking attendants.
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kikkari

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Re: Hasegawa Mikasa 1/350 Build
« Reply #8 on: October 03, 2006, 07:25:18 PM »

We've parked near Queen Marys and wandered down the grassy side of the dunes to the lake with the dog a few times on a Sunday but never caught you guys there.

I'll probably buy a bigger boat as a winter project at the Blackpool show and have something to sail there next year.

Back to the code...

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malcolmfrary

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Re: Hasegawa Mikasa 1/350 Build
« Reply #9 on: October 04, 2006, 01:58:08 PM »

Being a small club, we do tend to be a bit elusive, we changed our sailing to evenings when the car park charges went up, so for this year "they" lengthened the charge timing to 8.00 pm.  Still free on the road, about 100 yards away, though.
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uboatbuilder

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Re: Hasegawa Mikasa 1/350 Build
« Reply #10 on: October 05, 2006, 10:51:41 AM »

Hi just put pics of our tamiya 1/350 fleet in the warship section if your interested. Thay are all r/c conversions.

       Grant  :)
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uboatbuilder

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Re: Hasegawa Mikasa 1/350 Build
« Reply #11 on: November 20, 2006, 04:07:37 PM »

Made anymore progress kikkari?

Grant  :)
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