Schottel Drive

[Len OchiltreeParticipant @lenochiltree67043]

[Len OchiltreeParticipant @lenochiltree67043]

I fancy a Schottel Drive but will not BUY one, has anyone built something similar and simple ?.

 

Len.

[ashley needhamParticipant @ashleyneedham69188]

Len….no, by the looks of things. i have had a look at the graupner ones and they look a bit COMPLICATED to build at home? Ashley

[Paul TParticipant @pault84577]

Morning Len

As a Schottel Drive is basically an outboard motor that is mounted within the hull I cant see why it should not be to hard to construct a diy version, the only difficult bits are the 90deg final drive and the size i.e. no problem with a larger model of over 3ft but increasingly difficult as the scale diminishes.

So in part answer to your question it would all depend upon the size of the model that you intend to use the drive in.

Paul

[Bob Abell 2Participant @bobabell2]

Hello Boys

 

Can someone post a picture of this device…………..as I don`t get this 90 deg bit?

 

Bob

[JC Uknz 1Participant @jcuknz1]

I’m not sure abou the 90 degree angle but as far as the 360 degree requirement this could be handled by incorportating a geared wheel and spur cog attached to a motor to rotate the motor 360 degrees endlessly, wiper electric contacts etc.   I think the idea of an outboard motor is ingenious … much simpler than making the whole set-up as I’m sure one of our local Model Engineers did years ago when he was into boats …. must double check on that  and get back

[Paul TParticipant @pault84577]

This is a Schottel or Combi drive

 

Paul

[JC Uknz 1Participant @jcuknz1]

I hope TFC’s drawings don’t put you off becuase really the principle is fairly simple and likely easier in a model than real life becuase of the possibility of mounting the drive motor vertically.

For some dam reason the drawing doesn’t transfer properly[fixed now ] so you need to imaging the motor drive shaft coming down through the bearings and sub-deck to a gear assemble which transfers the drive to the propeller.

 

Drive motor, ‘direction gear’, and shaft are locked together and held by the bearings.   Then there is a second motor which rotates this assembly.  I used this system to rotate the gun turrent of a Mersey Class Monitor [WWI era]. 

 

I’d suggest checking the Meccano catalog for suitable gears if you don’t have access to a lathe and associated tools.

 

If you were to use ready-made outboard motors then perhaps you just use the top part of the drawing to control their thrust direction.

Edited By JC Uknz on 24/04/2009 06:28:28

[ashley needhamParticipant @ashleyneedham69188]

I cant help thinking that your main problem might be sealing the thing against water ingress, sitting as it is right underneath the boat. Nylon gears for the works are available here and there…”Hobbies” catalogue for instance. I have just made….something… using a Meccano worm drive, and oddly enough they are jolly noisy when spun at 9000 Rpm. A drive using Meccano will also end up being very large. Ashley

[JC Uknz 1Participant @jcuknz1]

If you keep the sub-deck above the waterline there should be no  problem as with a rudder tube.    If you use the right combination of motor and prop you don’t need 9000rpm. more like a tenth of that.    I’d say the main problem is building the ‘box’ of the gearbox rather than the gearing.

[ashley needhamParticipant @ashleyneedham69188]

I like the idea of keeping the sub-deck above the water line as a simple way of stopping water ingress. When yoy say “box of the gearbox, you are reffering to the bottom bit, the bevel drive to the prop? Using a direct motor drive at the top is a very neat way of dispensing with additional complication at that end, but unless your prop is VERY large and so can use a very slow revving drive motor you will still be faced with  a bunch of revs to contend with. For a large drive I wonder if you could get away with a belt drive from motor to prop? You can get some nice small toothed pully`s now, and this would mean the top motor would be mounted horizontally, the bottom shaft with the prop on similarly horizontal, and no gears to worry about. This would also be quiet. A tight fitting case at the top with a rubber tube type seal for the motor  should be reasonably watertight  ? Ashley

[Paul TParticipant @pault84577]

As the Actress once said to the Bishop “It’s all down to size” (not Colin)

It would be a relatively easy task to construct a Schottel drive for a model over 3ft long by using existing, off the shelf prop shaft components and Meccano or MFA bevel gears contained within a custom made housing (plastic piping springs to mind)

A vertically mounted motor might be easier on gearing but would occupy too much headroom within the model and would mess up the centre of gravity so I would opt for a horizontal motor to keep the weight as low down in the boat as possible.

The resulting drive would certainly not look accurate as the casing would be a rather bulbous affair but it would be cheaper which would meet Len’s original requirement.

Paul

 

[JC Uknz 1Participant @jcuknz1]

Another way could be jet propulsion using the same directional control system with the pump a tight but moveable fitting on top of the tube so that the tube rotates but pump remains stationary so it doesn’t disconnect the connection to outside the boat.  Electrical connections would be fixed here.    I’m thinking of a windscreen washer pump though I have no idea how they would stand up to contant use.

A lot depends on model size

[Len OchiltreeParticipant @lenochiltree67043]

Hi Guys,

You have put up lots of good ideas, I have been looking on other Sites as well,another idea that came up was using a flexible shaft and bent tube at 90degs.A curtain spring wire was mentioned.what do you think? could this work.

 

Len.

[Paul TParticipant @pault84577]

Len

 

You might generate a lot of friction and heat from a curtain wire being bent at 90deg even on a slow bend.

How big are you thinking of building this thing?

 

Paul

[TelstarParticipant @telstar]

Len

Have you looked at these photos from RC group they should fire your imagination

 

http://www.rcgroups.com/forums/showthread.php?t=524835&page=2

 

Tom

[Len OchiltreeParticipant @lenochiltree67043]

Hi Tom,

Yes I have looked a the photos before.

 

 

 

Hi Paul,

Its just that a member turned up at our Club with Tug no longer than a mouse mat with a Schottel drive fitted forward of centre of the hull and what this Tug couldn’t do, well it could do anything!!.

 

I do not have a size yet its all in the little grey cells.

 

Len.

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