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[KBIO]

Good morning DBS.
I agree with you that a canister will be better to reduce freezing the gas tank.
It has a larger exchange surface between liquid & gas : vapor pressure .
And the large surface of the envelope allows a better heat exchange between in & out !.
Now ! I am not sure that your N°5 jet (60 g/hr) is enough to supply enough heat to this boiler. Two Sun engines need a tremendous lot of steam They have to run fast and have no torque  >> need a small pitch & size on the propellers , thus consuming a hell of steam.
Setting a larger jet size will improve the flame but will help cooling down and lower gas pressure faster , with the consequences you know.
It will not enlarge the boiler heating surface anyway.
i am very interested in you project and I shall take profit of it. Thanks for sharing.


Sunny days are coming , I am eager to see your boat in the water !


[size=0px]only for it to stop close  enough to be reached with a fishing rod[/size][/u]
And then you realize that there is no beer left in the cool box !! ;-))

[KBIO]

Please Admin , erase this one.
I knocked the wrong button!

[Geoff]

I can't remember if this has already come up. To keep the tank warm in my models I use the oil separator/exhaust steam/condenser which sits touching the gas tank. This provides a gently warmth and at the end of a sail the gas tank is hand warm which is just about right. The exhaust steam then goes out through the funnels (pipe exits at the very top). Have a look at the Velox thread which shows the layout.


Hope this may assist.


Geoff

[steamboatmodel]

About the fuel tank cooling, you have to be very careful that you do not get the tank too hot. There are some burners that have been designed to be feed by the fuel in liquid form and then vaporize the fuel into gas. I built a tank and burner designed by Peter Arnot that did this, you started on gas and then switched over to liquid. I have a number of camping burners that are designed to do that.
Gerald.

[KBIO]

Hello!
I agree 100% with Geoff.
Although  a gas tank can stand pressure well above 20 b ; a bottle of domestic propane can stand in the Maghreb's sun for days without any problem. Look at the thickness of an aluminium lighter refueling canister and you’ll be amazed of its capacity to stand pressure.
What about a simple cigarette lighter forgoten behind the wind screen of you car when you are at the beach for hours? ( Some accidents happened though!)
Storing the gas is not a problem. Our problem is how to manage the pressure on the line.
Chart.

When there is a need for a big jet and if when the gas tank is small , the better solution as Geoff says, is to  feed the burner  in liquid form and then vaporize the fuel into gas .
Remember that roughly, 1 drop of liquid is equivalent to 270 time of this volume gazeifed at standard conditions = +/ 1 b abs.
It is so easy that when you used it once, you never get away from it.

Ex ;                       https://youtu.be/-DOlBcpjUAo
-The liquid comes directly out of the tank  (notice the small size =+/- 100cm3) and flows around the burner. I did place a coil behind the burner to cool down the (hot) gazeous phase before entering the Gas attenuator & regulator to avoid any damage on the membranes.
Note that the jet is a 45/100 = +/- 300 gr/h and the pressure remains the same all along the video. It cxan las for ever though !

-The second video shows where to position the coil to manage the flowing temp. Fingers are the best tool.
You can have a direct line from the tank, around the burner sleeve and to the jet if you don’t use these accessories.
                            https://youtu.be/_OtxLoBW3Ww


Last is a pic of the simpliest set up I use when I am too lazy to install regulator or other attenuator.

Hope it helps and that my explanation is not too dumb Regards from the Frog !

[steamboatmodel]

KBIO
I noted in the first video that you have a pressure gauge on the fuel tank, what pressures where you getting and was it steady or did it vary?
Gerald.

[KBIO]

Hello !
I forgot to tell : the flowing pressure remains steady @ 1 b (gauge) all along the video but can stand this pressure as long as there is liquid in the tank.
we should be able to read the gauge pressure on the video at some time.
Take into consideration that the ambiant temp is 11°C .
With  a summer temp of 20 °C, the tank pressure would be 2 b (gauge).


Would it be possible to share a drawing of Peter Arnot burner , please ?
Thanks for reading.
Cheers !

[DBS88]

KBIO thank you I will look into using liquid gas, that certainly looks like a useful option.
While I was looking at the video links I came across another of your videos testing a lovely looking Stuart Sun engine [size=78%]Tests with a 90mm / 4 blade propeller[/size]
The rotation speed obtained is 850 RPM at 2 b. The optimum speed is 750 RPM without pressure drop. Would love to know more about the boiler used to achieve those figures and anything else that may help. As you know the Torpedo Boat has twin Sun Engines and Twin 90mm 3 Blade Props, the boiler is designed to operate at uptown 80psi (5Bar) and drys the steam a little so your experiences are very valuable, thank you Dave

[steamboatmodel]

Hello !
I forgot to tell : the flowing pressure remains steady @ 1 b (gauge) all along the video but can stand this pressure as long as there is liquid in the tank.
we should be able to read the gauge pressure on the video at some time.
Take into consideration that the ambiant temp is 11°C .
With  a summer temp of 20 °C, the tank pressure would be 2 b (gauge).


Would it be possible to share a drawing of Peter Arnot burner , please ?
Thanks for reading.
Cheers !

I loaned my copies of the Model Boats Magazines that had the article in them and they were not returned.
I think the plans for the Arnot V4 are available from one of the plans services.
If I find a copy of the plans I will post them.
Gerald.

[DBS88]

KBIO thank you I will look into using liquid gas, that certainly looks like a useful option.
While I was looking at the video links I came across another of your videos testing a lovely looking Stuart Sun engine [size=78%]Tests with a 90mm / 4 blade propeller[/size]
The rotation speed obtained is 850 RPM at 2 b. The optimum speed is 750 RPM without pressure drop. Would love to know more about the boiler used to achieve those figures and anything else that may help. As you know the Torpedo Boat has twin Sun Engines and Twin 90mm 3 Blade Props, the boiler is designed to operate at uptown 80psi (5Bar) and drys the steam a little so your experiences are very valuable, thank you Dave

Hi here for interest is the link to the video [size=78%]https://youtu.be/W3wWIkaz6_Q[/size]

[KBIO]

Good morning.
I do not recommend this type of boiler as it is vertical and weights 5 kg all wet ! The blow torch (now that I know how to name it  ) is a 150 g/h
Also, in the video , I mention that the maximum RPM I can achieve without a steam pressure drop is +/- 800 RPM.
The Sun is designed to run faster but  in the water with this propeller and the shape of your boat , 1000 RPM will be plenty enough I guess .
Also it is designed for Higher pressure. A 60/80  psi in a boat will make it.
I would personally use a double Scott boiler for your setting. But this is a personal opinion and there people on this forum who can tell more.
I think of Ooooyah who knows very well both of Sun and the Scott.But there some other too !

[KBIO]

The inside !
12 x 5 mm boiler tubes.
It takes 5 mn to get 4 b.
Cheers !

[frazer heslop]

Peters burner was a modified Sievert blowlamp head
I have a similar design and will do a few pics next time in my playroom
cheers

[DBS88]

Before putting the boiler back in I thought I would try to see if my air brush compressor would supply enough air to run the engines, just wanted to make sure it all works before putting steam through. Well here is the result and yes I am a very happy man now. Next is to clean oil and double check it all over. Anyway here's a link to the long awaited time when we see these engines running.


https://youtu.be/wb_XawShVXY

[DBS88]

Ok things are moving on nicely now, have started disassembling the drive train to check all the lubricators work and to clean things up, after all this has been sitting idle for a long time. I am now more convinced than ever that this has never been run on steam. The unions and other fittings were only hand tight, all the paint looks pristine and there is no discolouration to the fittings. The photos of the engine are exactly as it came out of the boat I have not cleaned it at all. Also looking at the engine I have taken apart, my guess is that its a factory machined and assembled item. Bearing in mind its at least thirty years old its in stunning condition inside and out. I have now reassembled the engine and put some good quality engine oil in the sump and have cleaned and lubricated everything. Looking at the base that the engine has been fixed to, I believe that is far too clean for this to have been run. The second engine needs to come out next which is a bit more involved, so I am going to tackle that tomorrow.

[DBS88]

Have today taken the second engine out, stripped, cleaned and reassembled it. Having cleaned and lubricated both engines I have had them running on the bench on air for a few minutes, they are so smooth and vibration free, very happy. The engines run at 10 psi from my air brush compressor and turn over at a decent number of revs. So just need to clean the rest of the lubrication system and start reassembling ready to try it out on steam, hopefully over the weekend.Here is a video of one engine running on air
[size=78%]https://youtu.be/8sISydlrbCk         [/size]

[DBS88]

Today the engines went back in the boat and the boiler was connected. The weekend has been interesting, these engines are like new, one had a slight tight spot so has been run on the bench on air for a couple of hours and is now improved. One engine was definitely strong than the other, the one with the tight spot rotated slower and was easier to stop. I disassembled and reassembled, I believe the tight spot was with the shaft that transmits the rotation from the crank up to the valve. Anyway its now sorted. While the engines were out I took advantage of the improved access and place a kilo of lead sheet in the bottom of the hull. The boiler is resting in the hull in the right place and connected so I fired it up tonight. There are a couple of minor leaks to sort and a list of other jobs to do to complete the refurb, but tonight was a major milestone achieved. Here is a link to a  video https://youtu.be/LSvODiIzG0U

[ooyah/2]

Yves,
Further to your post No 110. Feb. 24Th regarding fitting 2 - Scott boilers to Dave's boat as you can see that it's far too narrow to fit double Scott boilers.
I think that his existing boiler is large enough to power the 2- Sun engines, but how how fast and long will have to be tried out at the lake.


You must remember this is a truly untested model and will require lake side testing.


George.

[KNO3]

Your engines run very nice on air. Looking forward to the steam test.

[DBS88]

I am going to start with a big thank you to everyone who has helped me get this restoration to this stage, it is appreciated, and you have certainly made the task easier. This afternoon I did some problem solving, which I enjoy. From the first run there were some leaks, a couple were easy fixes just tightened the bolts to the banjo fittings that connect the steam and exhaust to the engines. The next problem was steam passing down the oil pipe from the mechanical oiler. To solve this the main steam pipe assembly was removed. Then the small fitting that takes the oil into the pipes was removed. The nut at the top was seized solid so had to be persuaded loose with some heat from a blow torch. The ball valve and seating were cleaned and reassembled, then the whole steam manifold reconnected.
As you will remember these engines are geared together, so in effect they are one engine. One thing I had learned from stripping the engines down was that the timing on the engines was the same, they were connected at 180 degrees, so there were always two pistons up and two down. I moved the timing so that the pistons were at 90 degrees. The aim was to make the paired engines self starting and hopefully run more smoothly and quietly. The next thing I wanted to learn was the effect of putting the gas tank close to the burner, so rigged the refillable gas tank up to the burner and placed them together in the hull. The boiler was then fired and run, I was hoping to learn if the working temperature would be achieved quicker, but I had not filled the gas tank sufficiently and it ran out of gas after ten mins (what an idiot) anyway it was refilled and the boiler fired again, what I can say is that the flame burned consistently strong and the gas tank was warm to the touch not hot. Here is a link to the video of the second run on steam, the engines did run smoother, there is still more things to learn. [size=78%]https://youtu.be/dZJYVJrQiSc[/size]

[KBIO]

Good morning !
Smells and sounds good!
Cheers!

[Geoff]

Great progress and lovely to see and very well done indeed. I think you may need a larger gas tank depending on gas consumption but experimenting will see how it all works.


Next step is on the water or in the paddling pool!


Cheers


Geioff

[KNO3]

Good job David, I can't see any steam leaks and the engines run very well on steam too.
It looks like the oil pump is turning very fast though. You should check that it doesn't feed too much oil to the engines at that speed.

[SteamboatPhil]

Nice one Dave 

[DBS88]

Something a bit different tonight, I was sent a picture of the Ward Room from a Thornycraft torpedo boat destroyer built two years later than HMS Daring, its the ward room from HMS Bruiser. Have also attached a section of plan showing the layout of the ward room as built, from HMS Daring. So while these ships did incur the extra payments for hardworking, the style, elegance and workmanship that went into building them are stunning. Anyway thought the pictures were of interest.