Forum > Construction

Small Edwardian Paddle Steamer

(1/6) > >>

optima21:
I like the look of this paddle steamer from Hobby's in the UK and can remember it from their annuals 30 years ago.



and I plan to build something that looks similar but only 300mm long, and this will be my first attempt at scratch building a model boat, so for me it'll be an interesting project and hopefully it will be successful, but at this stage I have no way of knowing.

so the first thing I do was to carve a wooden hull as a prototype to see its possible and Im be constructing the majority of it from styrene.



at this stage it it would float as long as I can keep the weight down should work.

the first thing that I needed to sort out was the radio control. Im using Flysky as I can get small receivers that work down to 3.5V so can be used from a single lipo cell. I plan on using tank steering  without a rudder which has meant that I can use a reciever and 2 speed controllers to operate the model by using mixing the channels. I had issues with a new micro receiver and signal converter, which caused it to stop working occasionally, so I ended up using the old recievers that I'd been using on other models and ended up modifying the gimbals on the transmitter so that I could disconnect 2 channels so that I could mix then to do other things. its not as simple as unpluging cable, but cutting a wire and soldering a preset resistor in. Also shown is the final setup that I think I'll be using, The motors are N20 geared motors running at 250 rpm, I did try faster ones but they were just causing the water to cavitate. It also shows a close up of the speed controller, to reduce their footprint and make wiring easier I just stacked them on top of one another (with the receiver in the background). Just for scale the circuit boards are 15mm x 16mm. The battery, motors and radio control gear weigh 35 grams and should give an hours running time.

As I have a hull to play with, I think the next part of this project will be to make some simple paddle wheels with 8 and 12 paddles and different widths to see which will work best. For the time it will take its best to do it now rather than later and find that the paddle boxes are too small.





DamienG:
 :bravo :beer :clap

derekwarner_decoy:
This is looking to be a sound plan  :whistle.......your thoughts of complimenting the actual paddle shaft speed [via the speed controllers] plus additional paddle blade width is good

You mention the geared motors are 250 RPM 'unloaded', however the actual reduction ration wlll be rather high 5:1?, so with the level of mechanical advantage/torque, the reduced shaft speed in and due to the load induced by the water may well be in the 200 RPM ball park which may still be high enough to cause unwanted cavitation

In our case, paddle cavitation is a lot of huff+puff but going nowhere fast

Without going to the expense of a digital tachometer [$50.00 AUD] a simple elcheapo multimeter [$10.00 AUD] will provide you with current draw which the value of loading on the motor......unloaded = x milliAmp......thumb+forefinger on the output shaft = y Amps  :ranting

Keep us posted with your progress

Derek :beer

 

optima21:
The two motors that I'm using are sold as 3v 300rpm motors, and off load are both near enough 250rpm and speed can be adjusted easily via the transmitter. The speed controllers Ive used are Dasmikro 1S5A ones and can handle up to 5 amps and operate down to 3.5V

https://www.dronejunkie.co.uk/dasmikro-1s5a-micro-bi-directional-esc

but as the stall current for these motors is only 0.5A, Im looking to be using 1A speed controllers and and waiting for one of these to try it.

https://www.banggood.com/DOMAN-Mini-1A-Bidirectional-DIY-CW-CCW-Brushed-ESC-Board-for-RC-Drone-p-1649242.html?cur_warehouse=CN&ID=6134703&rmmds=search

these can operate between 3.5 V and 6V so would be able to operate these motors from a 5V supply which means that you can power them from a servo lead which adds to their versatility as Im looking to be using then to make tiny bow thrusters for other models

and for checking power consumption (amps and volts) while under load in water I ended up getting one of these USB power usage monitors, as they can work between 3.5V and 7V and measure upto 3 amps.  its not too bad for giving a rough indication, and I end up replacing UBS connectors with battery leads and replacing the plastic case with heatshrink to make it more compact and save weight.

Ive also made some new paddles for testing, the pics show drilling the centres and they are a push fit on the motor spindles. it took me a while to work out a simple way to align the paddles as I was originally going to over engineer a jig but it ended up being a case of drilling some holes on a pitch circle diameter (pcd), and there are websites that can calculate the position of the holes

https://littlemachineshop.com/mobile/bolt_circle.php

then the pins were pressed into place, they were made from 1.6mm welding rods. and the pins in the middle were a sliding fit in the paddle wheel centres.

the paddles were just aligned by eye and were "glued" in place with styrene solvent

I decided that I would try 15mm wide paddle wheels to begin with and have made then with 8 and 12 paddles. the one I have played with so far is the black one and thats 10mm wide. Im not wanting to go too wide with them as they may end up looking like they belong to a paddle tug rather than a pleasure steamer.

now I can have a play and do some testing to see how it performs, and the advantage of small models is that you can do this in a bath







optima21:
I had a play with it again and directional stability seems to be an issue, when I first ran it, the weight weight was on top of the hull, so was listing from side to side and the depth of the paddle in the water seemed to make it turn from one side to the other rather than going in a straight line. I also think 150 rpm motors may be fast enough and reducing the speed of the motors through the transmitter wont be as good as using slower motors and using the full stick travel. I also do think that 8 or 12 paddle wheels make much difference at this size, and that could also be because of the inconsistent performance of matching the speed of the motors.

I also tried it with 50 grams of ballast stuck to the bottom and that seemed to stop the listing from side to side, but directional stability.

so my next plan is to make a styrene hull with a shallow V below the waterline hopefully that will help, and this will be my second scratch built hull, and my first one was in steel and was 46cm long, this was done so I can test a steam engine when I get round to designing and building it


Navigation

[0] Message Index

[#] Next page

Go to full version