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Author Topic: Low Tension  (Read 251 times)

GG

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Low Tension
« on: January 13, 2020, 12:51:01 PM »

Some years ago I built a model based on a small ferry that sailed on the St Lawrence between Canada and the USA.  Only a modest speed was needed but a using a larger propeller than a small motor could directly drive.  Direct drive was favored due to its silence and in the end a stock "540" motor was used, much to the initial amusement of spectators who probably expected the model to self-destruct on its maiden voyage!  In fact it sailed smoothly and safely at full speed 'cos I was using a 2 Volt cell (from my days of starting glo-motors) to power it.

As this voltage was way lower than any of my ESC's (Electronic Speed Controllers) were rated for, the motor was controlled by a servo mounted resistance board and the receiver/servos used a separate six volt battery.

A little later and the idea came to replace the servo/resistance board with an ESC but still retain the six volt battery pack to power the RC circuits.  My thinking was that as the ESC didn't have a low voltage cut-off, it still could still provide power to the motor with such a low drive battery voltage.  But, control should be still maintained if the RC gear had a 6 Volt supply.  The ESC's BEC (Battery Elimination Circuit) not being switched into the RC circuits of course..!

It worked and no problems were encountered, the motor running smoothly from "tick-over" to its modest top speed. 

I be honest I have not had call to use this method in another model, the 2 Volt cell having finally expired plus my discovery of "Rock Crawler" motors (more turns for lower shaft speeds but still lots of torque) and my occasional attempts to rewind motors (something like a 100 turn 540 motor will cope with relatively enormous propellers).  It is however a potentially useful idea that might get someone out of difficulties, I'm thinking of a kit based on a canal boat which was supplied with a 540 motor directly drive a large propeller, not a relaxing sail.....!

Glynn Guest

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roycv

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Re: Low Tension
« Reply #1 on: January 14, 2020, 12:12:57 AM »

Hello GG.  I have lately finished the ferry you refer to.  Following on from your idea of using the low voltage end of motor performance I used a 20 volt motor (brushed) with 6 cell NiMh battery and this achieved much the same result and using a standard esc.  The prop is large and slow revving and the rudder turns a little more than I usually allow but she is very manoeuverable at low speed.

My superstructure is a combination of the two ferries in use on the service.  I had a long thnk about retaining the s/s on your design not so much from general sailing but from being hit by another boat.  I came up with the idea of lifebelts with securing rods glued in and slotting into 'extra seating' on the boat deck.  Which is why there is an extra ply strip around the s/s and it also strengthens the removable s/s.

I had fun searching for left hand drive vehicles at 1 : 43 scale and came up with a small selection, however further reading of the actual ferry service shows that I have more vehicles on than were normall taken on board.  My best buy was the motor cycle and side car which I bought for a few pounds to find out it was a bit rare. The young lady is not impressed by this method of transport for her illicit weekend.

 I have included the passengers for the various vehicles and there is a separate story for each one.  The crew have a uniform fishermans jumper and I took a few liberties with the windows in the s/s.  You can see a few barrels on the starboard side this is a hang over from Prohibition.   I have a time slot for the model it is the first Monday of August 1937 which was the August Bank Holiday in Canada at the time.
There are a couple of English sports cars rather hidden and these were on a hopeful sales drive going into the USA. Both are 1938 models so new for their time but little knowing that war was not far off.  There is a disgruntled driver from one of them on the top deck objecting to having had his day off spoiled!  The boarding ramps for vehicles do move to suit but the passenger ones are glued in place.  They are largely from coffee stirrers but I found you discard 80 % before you find what you want, I will not bother again.  The tiny hinges were a find from dolls house fittings.

I made my model from obechi wood which I had accumulated over the years, and as this is a little heavier than balsa I added another inch to the overall length of the boat to compensate, and with a lot of lead and batteries down low she is very stable on the water. I try and ballast at the ends of the boat to avoid the bobbing up and down motion of a small boat on the water. 

The mast is the aerial as well and is brass tube with a wooden cap, this is a push fit to make the electrical connection.  On the upper deck I used an ally gauze used for epoxy repairs to simulate a netting across the stanchions.  The smaller handrails at the bow are from model railway suppliers and are the rail knobs that go around the loco boiler.

The deck is much as per the plan with the vehicles and people being stuck down in place with a strong PVA glue.  It is planked with wider planks on the vehcle deck for wear and normal ones for the passengers on top deck.
She was built over a period of years and was my 'filler' between other models.
Hope you like my efforts.
regards to all.
Roy
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roycv

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Re: Low Tension
« Reply #2 on: January 14, 2020, 12:44:44 AM »

Here is a photo.Roy
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roycv

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Re: Low Tension
« Reply #3 on: January 14, 2020, 12:51:14 AM »

Here is another
Roy
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roycv

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Re: Low Tension
« Reply #4 on: January 14, 2020, 12:53:14 AM »

and the last one.
Roy
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roycv

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Re: Low Tension
« Reply #5 on: January 14, 2020, 01:05:43 AM »

Hi, just a thought but I calculated the suggested size of the water barrel, if full, would have caused serious stability issues.  So I took a piece of dowel and stuck matchsticks all the way round.  When dry I sanded the shape into a barrel and then hammered flat some brass wire to bind the staves together.  It is only if you look carefully you will see the staves are not tapered.
regards
Roy
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GG

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Re: Low Tension
« Reply #6 on: January 14, 2020, 10:15:33 AM »

Hi Roy,
          Nice looking model and great to see that you are prepared to adjust a published plan to suit your needs, too many people build exactly as per the plan only to find problems later.


I also like the consistency with vehicles of the same period.  I did once see a model based on this plan outfitted with cars of the 1900 period and modern inflatable life-raft containers.  I suppose you could conceive of situation to accept this but it still looked damn odd..!


As for the size of the water barrel, it was taken from the two models I based the model on.  Maybe it carried something less dense than water, smuggling alcohol across the boarder during Prohibition perhaps...?


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john44

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Re: Low Tension
« Reply #7 on: January 14, 2020, 10:17:59 AM »

Very nice Roy, how long did it take moving things around until you were happy with the layout
You can almost hear them chatting {-)
are the figures railway ?


John
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roycv

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Re: Low Tension
« Reply #8 on: January 14, 2020, 11:13:27 AM »

Thanks for the comments, most welcome.  I had a couple more vehicles but decided that they had to be placed so that they were able to drive on and drive off easily.

 Yes they are "O" gauge figures mainly rail passengers perhaps?  I bought a packet of 'mixed' people for a few pounds and painted them.  No crit' on the water barrel it was only when I went for my version I worked out how big one should be, it was due to be plumbed in but maybe when I have a spare moment.

For balancing I had the boat in the bath and got a rough balance, then left the boat on a shelf and pushed and pulled the vehicles until it looked about right.  The front two vehicles were the expensive ones so got pride of position I thought the lorry would be heavy and should be midships but not much point in putting an empty lorry aboard so she has a load to deliver.  The drivers Gaston and Maurice from Quebec are in the bar having a couple of jars for the road!
 Having been on a ferry with a motorbike you go to the front of the queue but go on last and just squeeze in.
The boat rides a little bow up but better than the other way.  The original was a grain ship built in 1904 and then converted to be a ferry, the other ferry on the service was built in 1878.  Fare was 1 dollar to USA and a free trip back!
bye for now,
Roy


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