DeSchelde Conversion......

[derekwarner_decoy]

Hi PD's........a number of members will know of my [10 year] SLOW  completion skills with my 1/24 stand off scale PS Decoy.........however I have committed to make a 1/2 life conversion of the hull into a 1/12 stand off scale PS DeSchelde.......a mythical/mystical vessel from old ...to achieve this a number of radical steps must be taken 

1. lower the hull deck by ~~~30 mm
2. remove the sponsons & relocate ~~~105 mm FWD & 30 mm lower than current position
3. Saito engine paddle shaft axis ~~~ 105 mm FWD & 30 mm lower than current position
4. total change of the boiler/engine/ ancillaries foot print with the boiler now AFT of the engine
5. major structural revisions to the hull planking above the waterline
6. the repositioning of components dictates that I will have many longer tube/pipe runs........but I can cope with that 

The principal reason for the vessel conversion is to have a fully open & viewable boiler & engine room.......... ...as I could not cope    with hiding the engine & boiler away below deck

I have uploaded a few images of the revised  boiler/engine/ ancillaries foot print in the Photo gallery this morning.........naturally the components are just sitting on the engine & boiler plate above deck level....they will be lowered into the hull in due course

I just hope I don't get run over by a bus before I complete the task......

Following is an image of DeSchelde.......Derek 

[Harold H. Duncan]

Nice concept Derek.
Best of luck with the conversion, and hope to see plenty of photos here please.
An interesting concept, and should show off the engine and boiler nicely
well done
kiwi

[derekwarner_decoy]

April 2018 - 4.8:1 Chain Reduction and major modification for the Saito Y2DR engine entablature to accept the chain pinion which is now on the paddle shaft axis....mock up with real components below....................

So De Schelde was not mythical or mystical ...just very little recorded history .................Derek

https://doctorferlemanstravels.wordpress.com/listspersons/othershipscrews/steamerdeschelde/

[kno3]

Why exactly do you need that chain reduction?
Your engine should be powerful enough without it. Besides, having the engine directly drive the paddlewheels would lower the rpm and thus the steam consumption.

[derekwarner_decoy]

Hullo Calan....trust you are well

The initial breakaway pressure and resistance to smoothly accelerate 890gm of paddle shaft including wheels, all on axis with the 4.00mm diameter SAITO output shaft ...from ZERO to say 50 RPM was beyond the ability of the drive

This [breakaway and massive over speed] occured both with warm engine or cold engine conditions

This has required the long & total hands up in the air of how to incorporate within the Y2DR engine frame or footprint to incorporate nominal 5:1 mechanical speed reduction to the final output paddle shaft speed .....this has hopefully been achieved with approximate 58% increase in paddle shaft from 4.00mm to 6.35mm  diameter....

Derek

[kno3]

I'm confused now...  Are you saying that the Saito engine wasn't powerful enough for direct drive, or that is was spinning the paddlewheels too fast?

[derekwarner_decoy]

kno3 ...the Saito Y2DR has ample torque and power to spin the 890gm of paddle shaft including wheels, it was however impossible to smoothly accelerate the mass from ZERO to moderate speeds  [50 to 70 RPM].............. Derek

[Hankwilliams]

Hi Derek and kno3,

it`s not only my experience, that for direct driving you need a real long stoke engine. Stroke between 20 to 30% of wheel diameter should be ideal.

Thomas

[kno3]

I see what you mean Derek. However, did you do the test under steam and with the paddlewheels in water? Because the engine would behave differently from a test on the bench.

[derekwarner_decoy]

Hi Calan.......

The test was under steam, however with a wooden clothes peg around the 4mm diameter shaft to simulate the load of water

Naturally this was difficult to understand any reality of clothes peg force, but suffice to say it was far more controllable and less painful than my burning thumb & forefinger 

I also note the comment from Thomas re engine stroke to wheel diameter ratio ....and so my Saito engine at 20mm stroke falls rather short of this 20% to 30% ratio

Using scale values, a 1:20 scale paddle shaft should be rotating in the vicinity of 200+ RPM......this I have seen on other models with scale surface area paddles......and whilst it may be true scale, some appear similar to food blenders making a lot of bubbles & wash......but going nowhere fast

So to counter or control the engine speed from ZERO, I concluded a paddle shaft speed reduction [like quite a number of OZ Murray River paddlers] as a way to harness the initial engine torque

I had the 10 tooth & 48 tooth chain pinions unused from 15 years ago...so have designed a few modifications around these components for the drive

As previously mentioned, the 4mm engine crankshaft ...being the paddle shaft has been increased  to 6.25mm

Somewhere down the track, the paddle wheels will be fitted with fixed wooden float blades.....increasing or decreasing the height x length of these wooden floats will be a very simple task, as the final tuning of paddle speed relative to resistance of the water

The second image is just a mock up of the paddle shaft with the 48 tooth pinion & some shaft bearing housings......the final number of bearings will be six [6]....[the flexible shaft coupling shown will not be used......they are not to scale & also exhibit  a disappointing degree of axial eccentricity] 

This is all again relative to that Bus as mentioned in October 23, 2011, 12:47:53 AM » 

Derek

[Hankwilliams]

Hi Derek,

your power plant gives a mechanically good impression. But it is not very suitable, to simulate the power of resistance of water with appliance like clothes-pegs. Probably with 1 : 4,8 gear reduction your power plant will be satisfactory in water - may be the rotation of the engine will be high and therefore also steam consumption. One must test...The attraction of our passion is groundet in try and error until the result is satisfactory. What`s the diameter of the wheels?