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Author Topic: Twin Screw adaptor  (Read 5050 times)

Builder1

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Twin Screw adaptor
« on: September 07, 2011, 03:42:42 pm »
Hi
Can anyone tell me where I can get an adaptor to run a twin screw vessel from a single engine???

Many Thanks
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essex2visuvesi

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Re: Twin Screw adaptor
« Reply #1 on: September 07, 2011, 03:48:01 pm »
yes Id be interested in one too... I have a Vietnamese Aquarama that I want to RC and there isn't the space for 2 motors of sufficient size
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treeboa

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Re: Twin Screw adaptor
« Reply #2 on: September 07, 2011, 04:11:47 pm »
two output gearbox, either belt or gear driven, trouble is you may have to make it yourself as i doubt theres anything off the shelf that will suit the placement of your shafts, add to this you will also have to use a bigger motor, not only will one motor be swinging the two props, but both shafts and also the gears/belts from the gearbox

you dnt mention what hull its going in, be mighty small if you cant fit a pair of 380/400`s in there, if thats the case i have seen similar were the motors were mounted one behind the other but slightly apart so the width taken up was just over 1 1/2 times the single motor
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MikeA

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Re: Twin Screw adaptor
« Reply #3 on: September 07, 2011, 04:17:03 pm »
when i built an outboard i ordered gears from here:
http://www.motionco.co.uk/gears-bevel-gears-c-32_41.html
do belts, pulleys, couplings, gearsm, rack n pinion the lot and take paypal.
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Colin Bishop

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Re: Twin Screw adaptor
« Reply #4 on: September 07, 2011, 04:33:57 pm »
Gears can be very noisy. You could use a single belt drive with a small pulley on the motor and larger ones on the shafts. However both props would need to be similarly handed which could affect steering unless you cross over the belt on one of the shafts to allow the use of handed props and in that case you would need some sort of vertical idler to stop the belt rubbing against itself.

Have you considered mounting one motor behind the end of the shaft? There is no special reason why it needs to be in front of the shaft if you are using belt or even gear drive. I have a boat where the motor is actually slung under the deck on one side of the model parallel to the shaft with a pulley drive. The battery is offset to the other side of the model to balance the boat.

Colin
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MikeA

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Re: Twin Screw adaptor
« Reply #5 on: September 07, 2011, 04:55:29 pm »
ive used gears and got admit they are noisy. i suppose there are many methods of running two props. if it was me id run two gears so the props contra rotate then use a belt to 1 of the prop shafts to the motor. if you use helical gears they are much quieter but harder to find
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irishcarguy

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Re: Twin Screw adaptor
« Reply #6 on: September 07, 2011, 05:04:23 pm »
A great web site Madmike thanks for that. It went straight into my favourites. Just a month ago I spent a lot of time looking for a bearing to fit a shaft .I found it in the heli section of the hobby store after a long search,I will not have that problem again. Mick B.
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MikeA

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Re: Twin Screw adaptor
« Reply #7 on: September 07, 2011, 05:08:22 pm »
found a better one :

http://www.hpcgears.com/

do helicals too
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Colin Bishop

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Re: Twin Screw adaptor
« Reply #8 on: September 07, 2011, 05:09:41 pm »
Quote
ive used gears and got admit they are noisy. i suppose there are many methods of running two props. if it was me id run two gears so the props contra rotate then use a belt to 1 of the prop shafts to the motor. if you use helical gears they are much quieter but harder to find

But that does rather mean that you need two gear wheels which exactly match the distance between your shaft centres - not easy to achieve and with zero adjustability! If you use a gear on each shaft and one on the motor to bridge them then you can adjust the motor mounting to get the best mesh but the props will not contra rotate - you need an extra idler gear for that.

Colin
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Martin (Admin)

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Re: Twin Screw adaptor
« Reply #9 on: September 07, 2011, 05:18:27 pm »
A double pulley on the motor and two belts out to each shaft (with pullies on them).  :-)
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MikeA

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Re: Twin Screw adaptor
« Reply #10 on: September 07, 2011, 05:22:07 pm »
suppose youd have to use 4 small gears rather than 2 large ones, the 2 centre gears could be positioned to allow for variations in spacing between the two propshafts.

ie:


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johno 52-11

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Re: Twin Screw adaptor
« Reply #11 on: September 07, 2011, 05:25:48 pm »
Have a look at Bill's Arun build He built a gear box to go on an IC engine and two shafts.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=24621.0
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MikeA

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Re: Twin Screw adaptor
« Reply #12 on: September 07, 2011, 05:35:41 pm »
nice bit of engineering in the gearbox.
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andyn

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Re: Twin Screw adaptor
« Reply #13 on: September 07, 2011, 07:16:28 pm »
If you were to send us a PM with your requirements im sure we could build you a box.

Andy :-)
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Jonty

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Re: Twin Screw adaptor
« Reply #14 on: September 08, 2011, 08:01:29 pm »
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ZZ56

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Re: Twin Screw adaptor
« Reply #15 on: September 09, 2011, 12:27:10 am »
MACK Marine have a two-from-one reduction gearbox with counter-rotating outputs, but it's not cheap.

http://www.mackproductsrc.com/Power%20p3.htm
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MikeA

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Re: Twin Screw adaptor
« Reply #16 on: September 09, 2011, 02:10:50 am »
crikey thats an expensive way to go about something fairly simple
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HS93 (RIP)

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Re: Twin Screw adaptor
« Reply #17 on: September 09, 2011, 03:43:19 am »
what type of boat and what size is it plus is it going to be high speed ? I think it may help rule out a lot of ideas and make it simpler to suggest a box.

peter
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Builder1

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Re: Twin Screw adaptor
« Reply #18 on: September 09, 2011, 10:44:54 am »
Its a 1/96 scale  1940's US Destroyer
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Colin Bishop

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Re: Twin Screw adaptor
« Reply #19 on: September 09, 2011, 10:56:04 am »
Surely there should be room for two motors then?

Colin
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wullie/mk2

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Re: Twin Screw adaptor
« Reply #20 on: September 14, 2011, 11:34:24 am »
I noticed on another Mayhem, topic
this set up,6 replies down see pics of single motor with 2 x props
www.modelboatmayhem.co.uk/forum/index.php?topic=26057.0
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dondecap

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Re: Twin Screw adaptor
« Reply #21 on: September 19, 2011, 07:25:52 pm »
hi mate.
the above post .... both screws would be turning the same way.............you need 'counter rotating',  which could be achieved like that with an idler gear [ same size as the shaft gear] between the motor and one of the shafts.
as said earlier put in two motors.........far easier. and with the option for separate control also. :)
regards
don
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essex2visuvesi

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Re: Twin Screw adaptor
« Reply #22 on: September 20, 2011, 05:41:34 am »
Quote from: Jonty on September 08, 2011, 08:01:29 pm
  How about this?

         http://www.graupner.de/en/products/d61f5025-0c1a-45d8-b1c1-71cad0232a68/1979/product.aspx

That looks interesting.... will have to investigate further methinks
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