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Author Topic: Queen Mary  (Read 56334 times)

Tug-Kenny RIP

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Re: Queen Mary
« Reply #100 on: February 06, 2017, 09:37:32 pm »


Thanks Peter.  I've not known such enthusiasm myself.  I'm really into everything about this ship. There's loads on YouTube and if you freeze the films, you can count the windows if you've a mind to.   %)

ken
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #101 on: February 08, 2017, 09:15:10 pm »


Loads of work done  (in my head).  and finally got the correct measurements to proceed..

I have made the new frames to the correct sizes and started fitting them today.  they are now glued in so I've started work on removing the old cut in half frames from the planking.   I was surprised how easy they were to remove from their glued position. I used a large pair of pliers and twisted the beams sideways, left and right,  and they just broke away leaving the planks undamaged but still glued together in a sheet of planks.

The plan is to re-use these on the new frames.



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Tug-Kenny RIP

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Re: Queen Mary
« Reply #102 on: February 15, 2017, 10:31:44 am »


Sorry it's been a while for updates.  I have been re-making the hull by using the old planking parts from the original hull.


I now know this a completely different job to making a new one.  It has been a nightmare trying to use the  'bent and glued together'  pieces and there is now more joins than I would have liked.  I  would not recommend this method to anyone.

Most of it was scrapped as I only managed to save the straight pieces.  I hope to smooth out the joins with filler now that I have a successful shape, and it's looking a lot better.

 
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Colin Bishop

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Re: Queen Mary
« Reply #103 on: February 15, 2017, 10:36:44 am »

The shape looks better now Ken.

Colin
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #104 on: February 15, 2017, 10:46:49 am »


 Thank you Colin.

She is more to scale now and it's  'wrongness'  (is that the word ?) has disappeared.  The shape looks right at last.

Just a question at this early stage.......... I have 4 props and tubes on order but am concerned with driving them.  (speed controller etc.)

I have 4 new 7.2 volt  Tamiya motors and thought that, as they are fast. I might wire 2 in series to slow them down for a 12v volt supply and an Action dual speed controller.
 
Do you think that the speeds will be slower and the current draw be more than the Action P98 will handle. ?

ken

 
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Colin Bishop

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Re: Queen Mary
« Reply #105 on: February 15, 2017, 11:29:18 am »

I am not really the person to ask on that Ken but it is not usually advisable to wire motors in series as manufacturing differences can mean that one will 'steal' power from the other and performance can be unpredictable.

The best way of varying the power is to vary the voltage using a speed controller with your battery voltage being set at the highest speed you are likely to need. If they are intrinsically high revving motors you might need to gear them down. My personal preference is to do that anyway using pulley drive as it allows the motor to run at a more efficient speed and reduces power consumption.

If you post the specs of the Tamiya motors on here then I'm sure that some of our more knowledgeable members will be able to give you a steer. It is of course a big model so you might have to do a bit of experimenting to get the right setup.

According to the Underhill plans catalogue I have, the 63 inch version of Queen Mary will displace 25.5 lb so that is the weight you need to push around the lake.

Colin
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #106 on: February 15, 2017, 11:58:58 am »


Thanks Colin,

I'll do a bit of research and see what happens on the test bench.

Cheers

ken
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John W E

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Re: Queen Mary
« Reply #107 on: February 15, 2017, 05:32:23 pm »

Hi ya there Ken

I have been googling the Tamiya motors of 7.2 volts; the majority of them seem to be very thirsty on the amperage.  Rather than amperage they tend to use the terminology of armature turns; at least that is what I think they are going on about.  To be honest with you, personally I think these motors would be rather too vicious for the model in ways of difficult to control.   As you are suggesting, connecting 2 motors up, I have a feeling what may happen (as Colin has suggested) is one motor would slow down and the paired (2) motor would speed up drastically and tend to overload the speed controller.

HMS Exeter has a 4 motor system in 2 pairs but the motors are 500s running on 6 volts and powered by a P94 20 amp speed controller.   In tests in a very small test tank seem to handle quite well.

I will put a link on to show you the layout:
http://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.msg400574.html#msg400574

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derekwarner

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Re: Queen Mary
« Reply #108 on: February 15, 2017, 11:58:53 pm »

Ken.....four cheap automotive ventilation fan motors from the wreckers would be ideal for a model of such a vessel ...low current draw...~~4 amps stall current....will easily spin large propellers [slowly as it is not a speed boat >>:-(]

With the larger motor case diameter, they could be set as staggered pairs as shown by bluebird....

A pair of ACTion ESC's would be a perfect match......

Derek
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #109 on: February 16, 2017, 02:23:36 pm »


Thanks for all the motor advice.  I did have a feeling about this set up, so glad I've mentioned it now.

I shall be going John's way with the layout as I have plenty of room along with Mr Action's fine gear.

Colin, the Tamiya motors are for the ' hot headed' youths which is why we don't use them in our trucks.  I always have to buy slower ones hence, my stock of new original motors is growing.

I'm now in  the market for 4 new motors.

Today I bought some P38 filler and plastered the hull with the lot.. Hopefully I will able to sand off most of it for a nice flat hull.  Here it is out in the winter sun, hardening up a treat.  It's beginning to look the part  (from a distance).


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Rottweiler

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Re: Queen Mary
« Reply #110 on: February 16, 2017, 07:57:31 pm »

thats a whole lot of sanding to do! Beginning to take on the shape you need!
Keep up the good work
Mick F
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #111 on: February 16, 2017, 08:29:13 pm »


Cheers Mick,  I've been told to do it outside with a mask on.    %)

ken
 
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Colin Bishop

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Re: Queen Mary
« Reply #112 on: February 16, 2017, 08:59:37 pm »

Now you've iced it, don't forget the candles first!

Colin
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Re: Queen Mary
« Reply #113 on: February 16, 2017, 09:24:57 pm »

Ken,
shouldnt take long to finish her now then lol!
Heres mine but not made by me!
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #114 on: February 16, 2017, 09:31:34 pm »


I knew about this one Mick.  It gives me something to aim for.   :}

It's certainly lovely.

ken
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #115 on: February 18, 2017, 02:08:44 pm »

We had a day outside with the power tools.   %%

Dust everywhere....  Thank goodness is it was windy.   When everything was sanded down we repaired to the warm workshop for sandpaper and a flat rubbing block.  I am so pleased as it came out rather well.


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Tug-Kenny RIP

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Re: Queen Mary
« Reply #116 on: February 18, 2017, 02:11:09 pm »


As the sun was out we decided to go for a light dusting of red oxide.  This will show any final flaws and moves me one step nearer completion of the hull.

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Tug-Kenny RIP

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Re: Queen Mary
« Reply #117 on: February 18, 2017, 02:16:35 pm »


Back to the motors problem.

What do the members think of installing brushless motors please.  ?   I have never been this route before and fancy the idea, as the ship will be quite heavy and will need a bit o 'Grunt'    %)  I have room for 35 mm propellers and 4 motor locations will not be a problem.  I will need to know speeds and sizes and amps sort of thing.

cheers

ken
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cos918

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Re: Queen Mary
« Reply #118 on: February 18, 2017, 06:39:56 pm »

Hi Ken
Slow scale brushless is not a easy as fast models .You will be looking about 6000 rpm on your props . so a 7.4v lipo would be looking at 800 kv . At 12v the kv would be 500 kv . to find brushless motors with the lower KV can be hard .You could look a reduction and use a higher rated KV motor . Have a look a Hobby King UK website to see whats avaible .


john
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Colin Bishop

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Re: Queen Mary
« Reply #119 on: February 18, 2017, 07:24:41 pm »

Ken,

I would have thought that the model could be pushed along quite adequately by brushed motors, after all it is a slim hull. No point in paying the premium for brushless motors and controllers if a conventional setup can do the job equally well.

I would cost out both options to see how they compare.

I seem to recall that Glynn Guest did write an article a while back which dealt with matching power requirements to model sizes. I also wrote a general article in the Model Boats 2011 Special Issue which I will email to you. It included some sample practical power setups.

Colin
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Rottweiler

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Re: Queen Mary
« Reply #120 on: February 18, 2017, 09:12:47 pm »

I was going to suggest you ask John Walravens to work out the power to weight ratio you might need,but I note he has already commented.
IMHO I really dont think you would  be advised to use brushless motors,as I feel they are more for speed,and that is not one of your requirements?
In my model of her,There are four old fashioned,but very reliable Renault car heater motors.I dont think they draw a lot either.These give me the performance required,and a little bit of speed should I need it to get me out of trouble.You will not need anything of this size,if they are still available,but I maybe talking out of my er hat,but I would have thought ordinary brushed motors of the Torpedo type would suit?
Mick F
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #121 on: February 19, 2017, 10:33:34 am »


Thanks for all the replies.

I am digesting Colin's write up on motors and will probably not go the 'brushless route' after all. It would be new to me and probably be wrong for this type of model anyway.  She is slim enough to slide through the water without too much force required.

Just had a look at her in the workshop and feel motivated to get on with the build.  Ain't it grand to have a hobby.

Cheers

ken
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ballastanksian

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Re: Queen Mary
« Reply #122 on: February 19, 2017, 02:11:59 pm »

People have been building Battleships as big as your Liner for years on Brushed motors, so as reccomended above stick to what you know for this one. I salute you for removing all the filler Ken, that was an epic abrasion  %%

She looks good on Red oxide, almost good enough just to apply masking tape and spray the Black/Charcoal on top.

Have you outsourced your Daily duties? You are motoring along with this build even taking the impressive decision to start again.
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Tug-Kenny RIP

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Re: Queen Mary
« Reply #123 on: February 20, 2017, 02:53:09 pm »

Work is not  'outsourced'.   I just keep going till I drop.   :}

I have been very busy with the smoothing out by rubbing down by hand with sand paper.  Scheesh...what a dirty job.  I've finally got her flat to the eye and she still need little pock marks filled.  I have cut the deck to go around the sides leaving a gaping hole in the centre and have it glued under heavy weights, so cannot do any more today.  (what's on TV !)

Here's a few views.

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Re: Queen Mary
« Reply #124 on: February 20, 2017, 02:57:09 pm »


I forgot to mention that I've cut out the anchor wells.   yes they are not symmetrical but taper upwards and the top edge goes on a slant.

I thought it looked wrong, but that's what the plans say.  The anchor will be tilted when pulled up into the recess.

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