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Author Topic: Captain class frigate build 1/144  (Read 1419 times)

cheekyninja

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Captain class frigate build 1/144
« on: February 07, 2021, 08:55:51 pm »

After having been away from modelling for quite some time (life got in the way a bit) I had a hankering to get back to it.  I want to finish HMS Charybdis but feel like trying something else before returning to her.

I saw Glynn Guest’s World War Two destroyer escort and decided to do something similar.  Some time back I bought a copy of the D.E. Hibbard plans* and am going to use them as the basis of a Captain class frigate with a disruptive camouflage scheme.  The Buckley and Rudderow had a common hull anyway and the hull is about 25.5 inches long.

I have added more flare to the hull and am also trying to also replicate that lovely deck sheer they had.  Access will be by the main superstructure coming off as one and sitting over a deck coaming.

One thing I do want to try is to squeeze two motors in, not for any performance reason but I have done a bit of Arduino programming and want to try my own ESC for fun.  That will require a bit of investigation as there are a couple of ready-made H bridges I have seen for sale online.  I think the motors will also be indirect drive so a box of metric automotive o-rings I have may yet have a use.  But given the ratings of the H bridges the motors may only be 140 to 280 size.  Any thoughts on that would be gratefully received.

Anyway, using as much scrap balsa as I can I have started building though at this stage the pictures are not very exciting...

*printed on that lovely heavy orange paper that they used to do the free plans on. :)
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Allnightin

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Re: Captain class frigate build 1/144
« Reply #1 on: February 08, 2021, 08:20:10 am »

That will require a bit of investigation as there are a couple of ready-made H bridges I have seen for sale online.  I think the motors will also be indirect drive so a box of metric automotive o-rings I have may yet have a use.  But given the ratings of the H bridges the motors may only be 140 to 280 size.  Any thoughts on that would be gratefully received.


Were the H bridges you had seen similar to the ones available via Micron:


dt_addx.pdf (micronradiocontrol.co.uk)
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #2 on: February 08, 2021, 06:22:10 pm »


Were the H bridges you had seen similar to the ones available via Micron:


dt_addx.pdf (micronradiocontrol.co.uk)

Hi,


Thanks for the reply, I had not seen those ones, I had found;


https://thepihut.com/products/l298n-motor-stepper-driver?variant=31985562550334&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMI2r_s8PDa7gIVxu7tCh2GUARkEAQYAiABEgKJ5vD_BwE


Or


https://www.robotshop.com/uk/motor-driver-dual-tb6612fng-v2.html?gclid=EAIaIQobChMInJqgvfHa7gIVEdTtCh0MJQW5EAQYASABEgKke_D_BwE


Early days in terms of which I will use so interested in any suggestions.  I have measured voltages and written to SD cards with the Arduino but not yet controlled a motor!


Thanks,


Dave
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Allnightin

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Re: Captain class frigate build 1/144
« Reply #3 on: February 08, 2021, 09:17:12 pm »

I had forgotten about robot shop but, noting it is in the Netherlands, I would probably avoid ordering from there until the new HMRC tax routines on post from abroad settles down.


Had you considered using a couple of continuous rotation servos as a cheap and compact way of powering models of this size?  I have a 1/200th HMS Abdiel minelayer running off two of these (after removing all but the last gear reduction stages)


https://www.rapidonline.com/feetech-fs90r-360-continuous-rotation-micro-servo-37-1335
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Rob47

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Re: Captain class frigate build 1/144
« Reply #4 on: February 08, 2021, 10:15:30 pm »

I ordered from Shapeaways and parts arrived with no border, or customs issues, don't forget as long as the order is less than £135, it attracts no import duty and should be charged at normal UK VAT rate.


Bob
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I will finish this model

cheekyninja

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Re: Captain class frigate build 1/144
« Reply #5 on: February 14, 2021, 02:07:22 pm »

Had you considered using a couple of continuous rotation servos as a cheap and compact way of powering models of this size?  I have a 1/200th HMS Abdiel minelayer running off two of these (after removing all but the last gear reduction stages)

Hi,
Thanks for the suggestion, I had not considered that.  If they are being driven from the receiver and get stalled is there the chance that the current increase could damage the receiver?
Dave
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #6 on: February 14, 2021, 02:09:28 pm »

I ordered from Shapeaways and parts arrived with no border, or customs issues, don't forget as long as the order is less than £135, it attracts no import duty and should be charged at normal UK VAT rate.


Bob
Hi Bob,

Thanks, good to know that.  I found a few other boards on that website so may yet get something from there.
Dave
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #7 on: February 14, 2021, 02:18:14 pm »

So, a bit more progress today.


I have some drawings of a Buckley class and decided to make the bow a bit fuller.  I added a new bulkhead further forwards to take the hull sides, and forward of this I will carve a bow block.  I am gluing that too but as it is just a block I have not included it in any pictures  :-)
I have also made both hull sides (one made from two pieces joined together from two with a reinforcing patch) and have glued on one side.


Slowly but surely a hull is emerging!


Thanks for reading,


Dave
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Allnightin

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Re: Captain class frigate build 1/144
« Reply #8 on: February 14, 2021, 02:51:03 pm »

Thanks for the suggestion, I had not considered that.  If they are being driven from the receiver and get stalled is there the chance that the current increase could damage the receiver?
Dave
As far as I can see from the servo data sheet, each crs servo has a maximum current of about 500 mA which is probably less in total than the maximum the typical (fairly cheap) Orange R610 6 channel receiver I use might handle.   I haven't had one stall to date in a number of models, including when driving a 1/35th military vehicle around.
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JimG

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Re: Captain class frigate build 1/144
« Reply #9 on: February 14, 2021, 07:10:43 pm »

No need for continuous rotation servos, just take the motor and electronics from a normal servo. As the feedback pot is no longer connected to the servo output the electronics behave just like a reversible esc. The feedback pot can be replaced with a small trim pot of the same resistance to save space. A normal receiver can cope with much higher currents than the servos will draw, even when stalled. What might be more of a problem is if you are using a BEC to drive the receiver it might not provide enough current for stalled servos.
Jim
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Allnightin

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Re: Captain class frigate build 1/144
« Reply #10 on: February 14, 2021, 08:16:55 pm »

Firstly a slight correction, the stalled current of the Feetech FS90R is 800 mA at 6V supply 700 mA at 4.8V.
Secondly the advantage of this sort of servo over a conventional one is that the deadband is appreciably larger than that for a conventional servo making it much easier to find the stop position using the normal joystick.  As shown here , the complete control board is pretty small but will drive a RE 280 type motor turning a 20mm 3 blade prop and two of these should be ample power for the Captain class model.  The stop position can be adjusted via the tiny potentiometer at the middle of the board.   At about £5 each they cost only slightly more than the same sized conventional servo.   
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GG

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Re: Captain class frigate build 1/144
« Reply #11 on: February 15, 2021, 12:06:11 pm »

Cheekyninja,
              I, naturally enough, am watching your build of this old plan with interest.  I had the same idea to "improve" the design by incorporating a smoothly curved hull sheer and built a second model based on these Destroyer-Escorts a few years ago.  It does look better, much better than the old plan.
Powered by a single RE360 motor and a 40 mm dia "RadioActive" brand propeller.  An input power of around 3W gives a speed of some 3 ft/s, a good dynamic match for the full size vessels.  Model plans and construction article are currently languishing the in the files of "Model Boats".


By the way, the idea of using a modified servo from Jim G, might not work too well in this size of model. Enough power maybe for those who like to convert small plastic kits but probably not for something this large. This idea is covered in more detail in the latest issue of Model Boats.
However, the problem of a limited deadband using this method, mentioned by "Allnightin", has never been a problem to me.  If unable to completely stop the propeller, it rotates so slowly that it doesn't move the model significantly nor consume much power.
Good luck with your modifications.
Glynn Guest
[size=78%] [/size]
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Allnightin

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Re: Captain class frigate build 1/144
« Reply #12 on: February 15, 2021, 08:16:48 pm »

Hi Glyn
Your point about slow revs when near the stop position when using a modified standard sevo is fully understood, especially in the context of a single shaft model such as your original design.  I have found that running multi shaft models with modified standard servos is more problematic as one shaft may be going the wrong way instead of stopped when in the middle of a manoeuvre and Dave said in his first post he wanted to have two shafts.  I don't know what sort of total weight the Hibbard model comes out at but it must be fairly close to my 1/200th HMS Abdiel which also about 2 feet long and runs well on two RE 280 motors driving Deans Marine 21mm 3 blade plastic prop which achieves a good speed and each motor being powered via a drive board from a FS90R crs.  For me the low cost of these servos (£4.75 at Component shop) has been a strong encouragement to go multi shaft.
Francis Macnaughton
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #13 on: February 21, 2021, 06:02:14 pm »

Cheekyninja,
              I, naturally enough, am watching your build of this old plan with interest.  I had the same idea to "improve" the design by incorporating a smoothly curved hull sheer and built a second model based on these Destroyer-Escorts a few years ago.  It does look better, much better than the old plan.
Powered by a single RE360 motor and a 40 mm dia "RadioActive" brand propeller.  An input power of around 3W gives a speed of some 3 ft/s, a good dynamic match for the full size vessels...


...a problem to me.  If unable to completely stop the propeller, it rotates so slowly that it doesn't move the model significantly nor consume much power.
Good luck with your modifications.
Glynn Guest



Hi Glynn,

Thank you for the post and pictures.  I am rather enjoying building this model, I had originally planned to finish it as a Rudderow class however there is something I quite like about the Buckley’s tall bridge that swung it.  Plus I would like to make a selection of Escorts so I can use the plan of HMS Tean as the basis for them and at this scale they are rather compact.

I do have an RS360 spare, did you have many problems with torque from that motor in a hull this size?  Is it direct or indirect drive?

Dave

A little more progress today. 

Both sides are on and I have brought the sides together to shape the stern.  Also added is the strip that will form the join between the deck and hull sides.

Ticking along nicely, thanks for reading.

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GG

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Re: Captain class frigate build 1/144
« Reply #14 on: February 21, 2021, 06:45:25 pm »

Dave,
        "RS360".....?  No idea what that might mean unless it ought to read RE360...?


The RE360 is a perfect match for this size and type of model provided.......
1) it's properly installed with motor and prop shafts aligned
2) decent coupling
3) suitable propeller
4) good electrical system
5) lubrication in the right places


These "RadioActive" propeller and shafts, might be "looked down upon" as they are cheap.  But, properly used, they work just as well as a more expensive item would in these smaller models.  I like the plastic props they have, nice thin blades with enough pitch to work well with motors such as the RE360 and 385 on direct drive.  The only thing to watch for is to keep the shaft inside the tube oiled, it can go rusty!


As for Torque, no problem with this combination (assuming the model is properly ballasted, which can apply to any model I suppose).
Enjoy this model, being creative and "doing your own thing" can be one of the most enjoyable aspects of this hobby.
 Glynn Guest
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #15 on: February 28, 2021, 04:10:37 pm »

Dave,
        "RS360".....?  No idea what that might mean unless it ought to read ...

... Enjoy this model, being creative and "doing your own thing" can be one of the most enjoyable aspects of this hobby.
 Glynn Guest


Hi Glynn,
Uhh, yes I meant RE360, sausage fingers on my mobile :).  I had a look at those Radio Active shafts too and they are a nice price, I am rather tempted by them.


So, progress this weekend.


I measured up and fitted the hull bottom at the stern, however this has highlighted a flaw in that the stern bulkhead it is 5mm off centre and the starboard hull side curves more more than the port.


I sat for a while wondering if this mattered and it probably doesn’t.   Unfortunately as I now know it is there and see it whenever I look I decided to take remedial action.  I have glued on some additional sheet to build up the thickness and once dry will shave it down with my razor plane.  As my razor plane is my favourite modelling tool anyway that isn’t too much of a hardship.


It also helps decides which side the tiller arm for the rudder has to go..!


Elsewhere on the hull I also did a first shaping and planed down the bottom to the sides; she is looking more and more like a boat.  So again, not lots of progress but I am mostly pleased with how she is going.


Thanks for reading,


Dave



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Akira

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Re: Captain class frigate build 1/144
« Reply #16 on: March 01, 2021, 01:11:40 pm »

Here is an alternative, if you have the room for standard sized servos, to stripping down a standard servo to create a proportional drive motor. They come out of the box as either a 360 degree continuous rotation servo with full F/R proportional speed control, OR a 180 degree servo that, with the addition of a servo extender, with provide 300 degrees of servo rotation.
I have used both the standard fast and the torque versions. The latter is better for driving something like a heavy turret, ect. The fast version, and I would guess the super fast version, would probably be better for smallish model drive systems where a higher prop speed may be required.
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Akira

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Re: Captain class frigate build 1/144
« Reply #17 on: March 01, 2021, 01:15:02 pm »

It would help if I included the link. SORRY. 
https://www.servocity.com/2000-series-dual-mode-servo-25-2/Also check the manufacturer directly at www.GoBilda.com
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cheekyninja

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Re: Captain class frigate build 1/144
« Reply #18 on: March 21, 2021, 04:39:22 pm »

It would help if I included the link. SORRY. 
https://www.servocity.com/2000-series-dual-mode-servo-25-2/Also check the manufacturer directly at www.GoBilda.com


Hi,
Thanks for the link, I will have to have a look.  I decided for this model I would go with separate motors but I would be interested to try using servos for propulsion in another model.


So, progress over the last couple of weeks.


I got the bow and stern blocks attached and had an initial plane of the hull.  Since then I have been sanding and filling... and sanding and filling some more.  I was still not quite happy with the stern so built it up a bit more. 


Today I sanded the bottom hull edges to get a more rounded hull form and also cut out the openings for the prop shafts (RE280/5 motors arrived a week ago).  I also discovered I have two Radio Active prop shafts in the bits box, thinking back I bought them from a model shop on Clapham High Street about 12 years ago when I lived in London and did not get round to using them(!).


A few progress shots but I am quite pleased with how she is progressing.  I think I need to build a stand soonish...


Thanks for reading,


David
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