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[richardabeattie]

I'm about to try and turn this kit into a working model.  Anybody already done it?  Will the paddle wheels actual move it along?  Any suggestions on a belt drive to convert the motor rpm into something slower with more torque?

[Martin (Admin)]

 
 https://www.revell.de/en/products/modelmaking/ships/civil-vessel/rheindampfer-goethe.html

[Plastic - RIP]

I thought about doing one of these but I looked at the hull and I didn't think there was sufficient bouyancy & stability to make it practical unless you're using a small battery and motor - all too fiddly for my hands.

[malcolmfrary]

What Plastic said, plus you have to remember that the real thing was intended to sail on a river.  The river intended did not normally get big waves.  A 1:160 scale model will experience waves 160 times as big as they really are, it would need perfect flat calm condiions.  The wind generating the waves, as far as the model is concerned, will be about 13 times as strong, and that over water much more open (to scale) than the intended original.
The paddles provided would need replacing with something more hydrodynamic, the kit ones are intended to look OK on a staic model from a safe distance. 
The hull would need extensive modification to make it much deeper to ensure that enough battery and motor/gearbox could be carried while keeping stability.  One thought was that with a deeper hull, drive could be via a pair of hidden props, allowing the paddles to freewheel.  Cheating, but what the heck?
That was my thinking looking at it about 15 years ago - times have moved on, but I still think that even with the lighter  and smaller batteries and, electronics and motors, it is still a step too far.
Driving tiny paddle wheels - how about direct driving them with either tiny stepper motors os very small brushless?  Might need some serious shopping or re-winding to get a low enough KV, but then again.......

[Plastic - RIP]

I'd go with a little geared drive or maybe a pulley on a common shaft between the paddles - but if you look at the hull, it's really long, narrow and shallow with so much mass hanging off the sides that I think it would easily capsize in the slightest wave - like a canoe - unless, as above, you considerably rework the hull so it's much deeper so you can add bouyancy & deep ballast to keep it upright.

[richardabeattie]

As with my 1/144 escort carrier I will add a short removable rod going down to a small lead weight.  The small weight on the end of that lever should do it.   The motor and battery will both be small and I think an elastic band belt drive will do. A mini rudder servo and no speed controller to save weight. Time will tell!

[warspite]

You could use a deconstructed servo as the engine the servo control board then acts as a miniature speed controller - plenty of discussion on the threads on how to do it.

[Allnightin]

I see the displacement is 744 tonnes suggesting that the model should weigh 182g to float on the waterline.  Any idea what the kit bits roughly add up to?

[malcolmfrary]

I see the displacement is 744 tonnes suggesting that the model should weigh 182g to float on the waterline.  Any idea what the kit bits roughly add up to?

Including the sprues, 120g.  Enough ballast to ensure stability will probably need extra buoyancy in the hull, so a rework to give more hull draught will still be needed.

[richardabeattie]

Nope - a small weight on a deep but detachable rod should provide stability without overweighting it.  I will post again when I know the answer.  And if anybody can give me a more specific steer towards instructions for using a servo as a motor and ESC I'd be grateful.

[Plastic - RIP]

I'm using these 9g mini servos:
https://www.ebay.co.uk/itm/Micro-Servo-Fs90r-Fitec-Feetech-Micro-360-Degree-Continuous-Rotation-Servo-Lt/263502066331?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 

It's continuous rotation at variable speed - I'm using it for a radar dish - but it's ideal for driving little paddle wheels - easy to fit in the boat and dead simple to connect a pulley onto the top.

[malcolmfrary]

Nope - a small weight on a deep but detachable rod should provide stability without overweighting it.  I will post again when I know the answer.  And if anybody can give me a more specific steer towards instructions for using a servo as a motor and ESC I'd be grateful.

Servos work by comparing a value that they get from the radio with one that they derive from their internal sensing pot.  If they differ, the motor drives the sense pot until they agree.  Co-incidentally, the sense pot is attached to the output gear, which rotates.
If the sense pot is mechanically separated from the output gear (e.g. by opening out the hole under the gear from a D shape to round)and the gears mechanical end stop removed, you have a motor control board, a motor, and a gearbox.  The (now non-driven) pot is now the center reference, the motor drives the gears, trying to reach agreement, but never managing.  Control is proportional, but with a very narrow dead band and short travel to reach full speed.  When using them to drive propellers, I used to use the transmitter trim slider tabs as an engine room telegraph - there was enough travel to give full speed.  The gearbox was dispensed with - drive was direct from the motor.  I'e only done it with "Standard" servos, it should work with smaller ones, but who knows?
The gearing to the output shaft is too great to give useful speed for driving paddles, but some ingenious folk with good eyesight and dexterity have taken drive from earlier in the gear train.
Very small geared motors do appear in the internet, look for something giving at least 200-250 RPM off the voltage you intend to run on.  This lets out using a "continuous rotation servo" which will let the paddles be seen to rotate, but will do precious little to drive the boat unless some serious mechanical surgery is done to take the drive from earlier in the gear train.

[richardabeattie]

Thank you for that  but I would not know an internal sensing pot from a wigwam!  Perhaps I should just cut open a standard servo and see what's inside.  Has anybody written or drawn the instructions for doing the job?  Sorry if this is all obvious to most of you but I'm a beginner.

[Plastic - RIP]

The link I gave - you can buy them off the shelf for £7 - no farting about needed.

[richardabeattie]

Thanks again - so if I have understood correctly the continuous rotation servo is in effect a small motor with a built in ESC.  Just what I need but alas the link says it no longer available from that seller.  I'll keep looking. 

[richardabeattie]

Blimey - I did not have to look far -the internet is full of them!

[Plastic - RIP]

They have the gearing of a normal servo so they run nice & slow - and they are variable speed so absolutely perfect for what you want.
As I said - I'm using one for a radar dish - I can set the speed so it looks right.

[Allnightin]

I wrote an article for MB magazine May 2017 issue covering the use of the FS90R in the Revell Lucky XI tug.   A key advantage of this particular one is that its dead band is considerably larger than the standard servos that Malcolm was talking about so it is readily controlled by the transmitter stick rather than the trim tab.  Another is that it is often to be found for under £5!

The picture shows my current way of adapting it - basically undo the 4 small bolts and take virtually everything out of it apart from the motor, electronics board and lead plus the small axle for the first gear driven by the motor.  Get the gear that fits the axle, drill out the hole enough for a short length of thin walled brass tube (whose internal diameter is a good fit on the axle) to be a tight fit inside then slide the modified gear back in place.  Your power unit is now ready to use for direct drive of a small prop - I use the Deans Marine 3 blade 18mm plastic ones with good results.  Connection to the prop shaft is achieved by a suitable piece of electric wire insulation. 

[Allnightin]

Further to my last, for a paddle steamer you would probably want to have two stages of gear reduction rather than the one stage I use.  All that means is you drill out the second gear after the motor instead of the first.

[RST]

I don't know if this is too big, but I have one of these small geared motors (type 2) and the micro controller for a radar on a build at the moment.  I've not used the controller before but I have the motor.  The shaft in the pic actually isn't particularly fixed, you can push it through 50% -so for a "micro" paddler you have two drives in one (if you don't want to control the paddles independently).  I have it in mind to try this myself on a micro paddler of some sort at some point.  Otherwise two c/r micro servos would work.


https://www.ebay.co.uk/itm/Radio-Controlled-RADAR-Controller-and-Motor-Kit-for-Model-Ship-Boat-Yacht/123744287974?hash=item1ccfbbfce6:m:mUJwLM49yYw552XgWKuRFvg&frcectupt=true

Rich

[Plastic - RIP]

That's quite expensive and not that small - the continuous servos are under £7 and are self-contained and variable speed from the Tx

[malcolmfrary]

An update on the weight of the thing and an admission of a cock-up on my part  .  Having had a niggling suspicion about the parts I weighed before, I rechecked, it looks like it was THE WRONG BAG IN THE BOX.  So I found the right plastic, and the bad news is that the kit plastic on the sprues actually weighs 480gm.  Even if the weight was only half sprue, that's still 240gm for the kit, meaning that a lot of plastic will need to be shed before it can carry anything and float.

[richardabeattie]

I've now got my hands on the rather battered ebay'd kit and now see that the job of converting it is beyond me.  First, the hull is narrow and very shallow so I'd need an extremely small mechanical fit-out. And second, the top weight is indeed too much.  Something could be done by omitting all the internal seating, cutting away all the internal decking and replacing the heavy window glazing with film. but even then it would need some added buoyancy.  I live and learn!

[Plastic - RIP]

I'd either get rid on ebay again or just enjoy building it as a static model - it's a nice, pretty model so it will be a good ornament.

[johnjake]

I'd go with a little geared drive or maybe a pulley on a common shaft between the paddles - but if you look at the hull, it's really long, narrow and shallow with so much mass hanging off the sides that I think it would easily capsize in the slightest wave - like a solo canoe - unless, as above, you considerably rework the hull so it's much deeper so you can add bouyancy & deep ballast to keep it upright.

what kind of Goethe model you are using that will interesting you say that narrow like canoe i think you are talking about kayak that are thin and narrow and closed from all sides i have canoe hobies cat 16 '' that is wide and log and open from all side kayak is light weight conform me so model details if possible because i am interesting ti view your Goethe model....?