3 motors 1 ESC !

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29 December 2009 at 19:17 #5061
ron hawes
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@ronhawes49865
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29 December 2009 at 19:17 #24797
ron hawes
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@ronhawes49865
I am building the titanic which as most of you know had three engines so i want to put 3 electric motors in my version,

the rudder is to scale which was never big enough on the real ship so the scale 1 is not going to be much good, but with three engines i want to cut one out when turning i.e. when turning to port the starboard engine cuts out leaving the center and the port engines running, im sure i can do this off micro swithches swithched on and off via the servo arm,

does anyone know if i can run three engines off 1 ESC (im planning to use 12v 540 motors) and would anyone have a wiring diagram if this was possible or any ideas to make it possible?
30 December 2009 at 00:16 #24802
Telstar
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@telstar
Hi Ron

What you are proposing is feasable. I can supply a diag if you wish.

But have you considered using an electronic solution, Dave Milbourn at Action electronics does a combined rudder/ motor controle system I beleve gives variable outer motor speed controle combined with rudder movement

http://www.action-electronics.co.uk/mixers.php

If you do run 3 motors off one Esc do make sure it is capable of carrying the full current of all the motors together.

cheers Tom
30 December 2009 at 10:50 #24803
ron hawes
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@ronhawes49865
thanks tom

the web site link is very usefull,

but i really want to do as much as possible myself so would it be possible to put that wiring diagram up for me thnks ron
30 December 2009 at 16:16 #24804
Telstar
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@telstar
Ron sent PM to you

Tom
30 December 2009 at 18:38 #24808
ashley needham
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@ashleyneedham69188
Ron dude….awesome …will be massively heavy. My Titanic is a mere mintanic at 48 inches. I have used three toddy MFA 385 motors on 6v even, and it provides a more than sufficient “scale” speed. It does take a long time to stop and reverse though!!

I have made the rudder MUCH larger than scale, and it swings over a fair bit, in order to provide steerage. I am not sure just how much more effective the steering would be with the ability to twiddle with the individual props when turning…..

there are only three….the centre one needs to be going full blast in order to push max water over the rudder, and the props are not particularly splayed.

This was one of the weaknesses of the BISMARK.. despite being a , in theory, modern ship, the hull was based on a WW1design, as the Germans did not have the benefit of post ware development and there were only three props….when the rudder was knackered by the Stringbag torpedo, they only had effectivly one prop a side to try and steer with, and these were not canted out much…and so its fate was sealed (it probly wouldnt have made much difference, as they had no backup).

I would be tempted to fit slightly oversize props (4 bladed in the middle of course) and have the motor drive geared down. i would arrange MORE power to the centre shaft in order to have the best rudder effect. This can be rotated faster than the others, as per the original I believe, possibly by direct drive. I would put some MFA 800 motors in myself with a ship that size, they only rotate at 5000 rpm, and can turn biggish props (stand by for dissagreement!)

Ashley
30 December 2009 at 19:24 #24810
ron hawes
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@ronhawes49865
ashley thanks for the reply

ive thought about having different size screws,

on the original TITANIC the center prop was 4 blade and smaller thasn the outer two three blade screws,

but they surely must of had different ratios otherwise the outer two would cause the center one to drag in the water or vice versa,

i was going to use three 3 blade brass screws the outer two going in one direction and the center one opposite,unless anyone knows how to calculate the thrust of different size screws inc the extra blade on the center one
30 December 2009 at 19:52 #24811
ashley needham
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@ashleyneedham69188
The centre prop was driven by a steam turbine, and this used the exhaust steam from the outer reciprocating engines. it did go faster then the outers, cant remember the difference.

The starboard and centre props turned clockwise, the port one anti-clock as viewed from the rear…on the real ship.

I would certainly fit a 4 blade prop centre, for looks if nothing else. I would also make it slightly larger than scale again to assist steering. The centre prop was slightly slimmer bladed that the outers.

As for efficiency, Unless there was something to compare it to, you wont notice the difference.

Unless you havnt already, do yourself a favour and purchase

“RMS Titanic- a modelmakers manual, by Peter Davis-Garner isbn 1-86176-227-5

His Titanic was only 18 feet long mind you……

HE plated his entire hull with plates as per the builders drawings , and punched an estimated 61,000 rivets into the plasticard plates.

Bob..eat your heart out !!!

Ashley
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