Padleducks logo Paddleducks name

Welcome to Paddleducks..... The home of paddle steamer modelling enthusiasts from around the world.



+-

Main Menu

Home
About Us
Forum
Photo Gallery
Links
Contact Us

UserBox

Welcome, Guest.
Please login or register.
 
 
 
Forgot your password?

Search



Advanced Search

Author Topic: New project started: Irrawaddy paddler "Mindan" 1948  (Read 813 times)

Offline derekwarner_decoy

  • Gold Subscriber
  • Senior Member
  • ****
  • Posts: 2396
  • Gender: Male
  • Wollongong - Australia
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #15 on: February 10, 2019, 10:46:14 AM »
Well Thomas....we see  :gathering ...that you had plenty of 20 mm diameter 90 degree bends & caps left over from the boiler internals

I must admit recently seeing a few French built gas tanks that are long & like a sausage  :whistle .   and a builder Daniel Buroard   some years back, built a duplex set of tanks........but I have not seen a gas tank in the shape of a U ......but :thinking ....why not?

In Australia, such a privately constructed gas tank would be required to a 25 Bar test pressure from a cold water static test

Looking at the form of your construction, the wetted surface area on diameter for the silver soldering on the 90 degree bends & caps is approximately x 3 of the general endcap surface area we see on Commercially built tanks....so if the wall thickness of the copper tube spools & fittings is adequate....& properly soldered....the tank should pass with flying Colours

Do you attempt a calculation on theoretical volume, or a more acceptable nomination of the weight of gas able to be filled.......[about 220 gms?]

Derek


« Last Edit: February 10, 2019, 12:20:53 PM by derekwarner_decoy »
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Offline Hankwilliams

  • Full Member
  • ***
  • Posts: 472
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #16 on: February 10, 2019, 09:35:12 PM »
Hi Derek,
yes, it`s also necessary to see the theoretical aspects of gas fired installations. The inside diameter of the copper tubes are 26 mm, of the angles 28 mm. Lenght altogether is 270 mm, this gives a theoretical volume of 143 cc.
Weight of propane/butane is about 0,6 gramm/cc, the result is a weight of about 85 gramms - theoretical. Practical of course it`s less, may be 70. It`s important, that the liquid gas is vaporisized, before reaches the burner, otherwise the flame will be extinguished or the nozzle will obstruct. This can be avoided by a longer connection between gas tank and burner.
To pressure test: I don`t have the possibility to make an exact pressure test with gas tanks, it`s more a matter of experience. In practice, the silver soldered tank is filled with gas and put in a cold water bowl. If no leaks are visible, the water will gradual slowly heated until ca. 80 ° Celsius. This temparature will never reached in later practical use, are no leaking at this temperature shows that the gas tank is ok.
I`ve made about 15 gas tanks with this method and never saw any problem. For further security I made a tightness test with flame at the gas junctions before every heating up.
In practical use with steamboat models it`s absolutely necessary, that first the spark flame (?) will be at the burner and after this, the gas valve will be opened. With this precautionary measures the running of a steamboat model is pure joy! Now I hope, my post is not too long?
Many regards Thomas

Offline derekwarner_decoy

  • Gold Subscriber
  • Senior Member
  • ****
  • Posts: 2396
  • Gender: Male
  • Wollongong - Australia
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #17 on: February 11, 2019, 07:52:50 AM »
Thanks Thomas.....no, your postings are never too long....we always enjoy at reading times  :gathering

Seriously thou, your posting does open up the scenario that gas tanks do not necessarily to be that one short or long sausage  :ranting

Looking forward to seeing your long stroke [36mm?] engine coupled with your space restriction...which we know you will resolve

Derek  :beer
« Last Edit: February 11, 2019, 08:54:28 PM by derekwarner_decoy »
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Offline Hankwilliams

  • Full Member
  • ***
  • Posts: 472
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #18 on: February 11, 2019, 08:46:16 AM »
Thanks Derek - just one thought about gas pressure and temperature: The Mixture of Propan/ Butan is 30 to 70, this gives a pressure of nearly 18 bar at 80° Celsius - not enough for Australia regulations, but I think, for practcal use it`s safe.
The Graham engine has a stroke of 16 mm. But the wheels diameter are only 85 mm, so I hope the torque will be sufficient.

Thomas

Offline Paddlemex

  • Junior Member
  • **
  • Posts: 16
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #19 on: February 12, 2019, 10:55:50 AM »

Hi Thomas,

The gas tank looks great and, with the calculations you have posted, safe too.

But …. why the strange U shape of the tank? From the pictures there seems to be enough space to fit a "normal" cylindrical tank.
Or is it - as Derek says - because you a lot of of 20mm 90° bends left over? ???

Jurgen

Offline Hankwilliams

  • Full Member
  • ***
  • Posts: 472
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #20 on: February 12, 2019, 08:18:15 PM »
yes, the main reason was that one can buy this copper tubes and angles in every hardware/installation shop for low costs. A bigger diameter brass tube I had to order at special shops. The volume must be sufficient, but the tube should not be too long for this boat - I also have made gas tanks from a longer single 28 mm copper tube with one angle at it`s end where the gas valve was installed. I now have 20 steam driven boats, of course it was also necessary to pay attention for practical and not too high costs.

Thomas

Offline Hankwilliams

  • Full Member
  • ***
  • Posts: 472
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #21 on: February 18, 2019, 08:01:45 AM »
paddlewheels built and installed!
This was a one week work with 0,8 mm brass sheet, M2 and M1 screws and so on. The wheels are turning now quite well, but improving should be possible. Diameter is only 85 mm, lenght of the paddles 65 mm. The angles of dip in and dip out are now good as you see at the pictures.

Offline DamienG

  • Administrator
  • Senior Member
  • *****
  • Posts: 1035
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #22 on: February 18, 2019, 03:16:40 PM »
 :bravo :clap :bravo :clap :bravo :clap :beer :beer

Offline Paddlemex

  • Junior Member
  • **
  • Posts: 16
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #23 on: February 19, 2019, 12:53:26 PM »

Nice Thomas, and quick.

From the last picture it seems that have placed the eccentricity forward AND a bit down. Is that so or is it an illusion due to view angle?

Jurgen

Offline Hankwilliams

  • Full Member
  • ***
  • Posts: 472
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #24 on: February 20, 2019, 03:39:09 AM »
Hi Jürgen,

the eccentricity in every case is forward of the paddleshaft, but aproximately on the same level. The wheel should be turning easily and without squeezing. It`s a question of trial and error, to find the best point for fixing the wheel excenter.

Thomas

Offline Paddlemex

  • Junior Member
  • **
  • Posts: 16
  • Gender: Male
Re: New project started: Irrawaddy paddler "Mindan" 1948
« Reply #25 on: February 21, 2019, 06:41:39 AM »

Thanks Thomas,

I was intrigued because on the picture it looks like it was downward a bit.
I think that during my research on the internet I have seen a mechanism where additional to forward the eccentricity was also somewhat down. But, again, I may be remembering something that can not be.

Jurgen


 

Powered by EzPortal