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Author Topic: Vosper rttl 2751 motorsetup  (Read 2974 times)

mark69

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Vosper rttl 2751 motorsetup
« on: March 06, 2016, 09:11:25 pm »

Hi all ,I've a set of plans for the Vosper rttl at 35" .The plan shows a single engine and other builds show twin electric motors ! As I'm wanting a twin set up but do not know the finished all up weight how would I calculate which motor and ESC I need ,I've plenty of 2500 3s lipo,s !! Any help would be great thanks
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howyson

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Re: Vosper rttl 2751 motorsetup
« Reply #1 on: March 14, 2016, 11:01:36 am »

Hi


My RTTL is built from the Vic Smeed plans. It is 34 inches long and weighs 3.4kilos so tends to sit marginally low in the water. It is powered by two 500 motors controlled via a 25amp ESC. The main battery is a 72. volt Nimh unit and I am happy with its performance.


Check out my post http://www.modelboatmayhem.co.uk/forum/index.php/topic,18707.msg331490.html#msg331490 or the youtube http://youtu.be/ueKzr-Y7v0s[/size]
Howard
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canabus

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Re: Vosper rttl 2751 motorsetup
« Reply #2 on: March 14, 2016, 12:13:51 pm »

Hi
 A couple of 35mm 3639-750kv brushless motors on 3S Lipo's, pair of 45A ESC's, a Y connector to link the ESC's and a pair of 35mm 3blade props.
The sister motors to the 3639-750 kv's are the 3639-1100kv motors but these require 60A ESC's.
The 750's on 3S rev tops at 8325 and the 1100's rev tops at 12210 rpm.
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John W E

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Re: Vosper rttl 2751 motorsetup
« Reply #3 on: March 14, 2016, 01:18:41 pm »

hi there

as me mother used to say 'hold the horse I want to get off' cos - we have crossed too many bridges and we aren't at the river yet :-)

First question is - what materials are you building from/how are you intending to build it?

The model of the RTTL that Howway Son built - is built the same way as Vic Smeed plans tell you too - e.g. for an I.C. engine and therefore 90% of the bulkheads that the model is made from - is 6mm thick ply and sold - without the middles removed in other words. As Howway Son says it weighs in the region of about 3.4kilos.   

The model I built which is the RTTL 2751 and its built in a completely different style.   The framework or bulkheads is only 3mm ply and is also double diagonally planked with 1.5 thick planks and then layered over the top with 0.5 mahogany planks.    The total weight of the hull is in the region of 1.5 lbs, which is extremely light.

She is powered by 2 Mtroniks vision motors which push her along at a good lick.   I dare say if I stripped out all the sound modules, speakers amplifiers etc., to lighten the weight yet again, I would give any brushless boat of the same size a good run for its money.   The only drawback is that both props rotate in the same direction as in the real lifesized boats - so she has a tendency to dive to one side and she has a lot of tail torque.

Think about this before we go on to what size motors we need.    i.e. think about the hull and  how we are going to build and how light it is ?

http://www.modelboatmayhem.co.uk/forum/index.php/topic,20758.50.html

aye

John





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mark69

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Re: Vosper rttl 2751 motorsetup
« Reply #4 on: March 14, 2016, 08:32:02 pm »

Hi guys thanks for your replys s ,your motor set up is helpful thanks ,as for building this boat l under stand  it was designed for a IC engine and it's be drawn with this in mind ! As I'm going electric I'm useing lite ply and 1.5 abechi ply ,can't see the need to double plank with mahogany as I'm painting the hull but it will be sealed both inside and out ,as I would rather add ballast than build weight I will build as light as possible . thanks again for you help ....mark
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mark69

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Re: Vosper rttl 2751 motorsetup
« Reply #5 on: May 23, 2016, 05:24:15 pm »

Hi all I've now started the Vosper build and I'm only going to use ply and spruce in its construction ,I know the plans do show balsa being used but as you need to add more sealer to balsa the weight saving is not an issue ,if I can remember how to add pics I will but so far the keel is laid a the the 6 bulkheads are glued in place .......mark
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mark69

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Re: Vosper rttl 2751 motorsetup
« Reply #6 on: May 31, 2016, 11:36:31 pm »

Hi thought I would add a pic of my vosper build ,it's from the Vic Smeed plan ,I've seen other builds where the bull was built upside down but as the plan is very vague as a lot of build process it seems to be left upto the builder to interpret the drawings ... mark
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mark69

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Re: Vosper rttl 2751 motorsetup
« Reply #7 on: June 05, 2016, 06:31:41 pm »

Hi just a few more pics now the hull is the right way up ,I've had to add more stringers to slow the planking to curve seem to been missing on the plans ?
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