Construction of French Spar Torpedo Launch of 1889

[Bierjunge]

Hello PDs,

I think it's time to step forward and tp present my current project, a live steam model of a french spar torpedo launch of 1889. The plans of the prototype can be found online at http://www.servicehistorique.sga.defense.gouv.fr/02fonds-collections/banquedocuments/planbato/planbato/fichebato/fichbato.php?id=521
As 1:10 model, it will have a length of 1,25 m and a displacement of 7 to 8 kg.

The first picture shows the general arrangement of the drivetrain components. I decided to build the boat from the inside to the outside, not to get into unforeseen packaging conflicts. Therefore, I temporarily mounted the drivetrain to a board, controlled the package comparing it to the hull lines, and did all the tubing in order to test it and break it in under steam.

On the test bench, we have now: A TVR1A engine from Graham, a double flue boiler and gas tank from Regner, a gas pressure regulator from Laspe and a 90 mm propeller and driveshaft from Raboesch. A water filled tub serves as load simulation.

Today was the magic moment of the first test run under steam. The burners ignited at the first attempt, all tubing proved to be sufficiently leakproof, and the Laspe regulator worked perfectly: Without the need of any further adjustments, the boiler pressure was at a constant 2,8 Bar, no matter whether the engine was shut off or running at full load.

At half throttle, it ran at 600 rpm; at full throttle well above 800 rpm (where the bicycle speedometer misused as rev meter came to its limits). That was surprisingly almost exactly what I had predicted using my excel engine calculator at http://www.paddleducks.co.uk/smf/index.php?topic=3262.msg14351#msg14351 .

Anyway, enough power to churn up the brake tank in a very promising way.
Next action will be buying plywood for the hull mould...

Regards, Moritz

[derekwarner_decoy]

Hi PD's,......&  Moritz...I particularly like the night time snap in the boiler room with those two beautiful BLUE gas flames ...looks like optimum combustion with the white flame body etc  ..... your tube work is also  ...you know what I mean....nice & square & level & straight [except for the bend bits  ]

I cannot see any evidence of...but has your double flue boiler have any additional insulation under the wooden lagging?

 ...would be very interesting to see more snaps as you steam build & hull progress etc

regards Derek

[Eddy Matthews]

That looks really nice Moritz - The steam plant is surprisingly like the original in the drawings

As Derek said, I'd certainly like to see more photos as the build progresses, it should look magnificent on the water!!

[derekwarner_decoy]

Hi PD's ....& I know Moritz I said ....

"I particularly like the night time snap in the boiler room with those two beautiful BLUE gas flames ...looks like optimum combustion with the white flame body etc"

But something is not correct here in this view....the hottest point of the gas flame will be is approx 25 mm inboard only  or am I missing something

All explanations with live steam are a learning curve for us all........

[Bierjunge]

I cannot see any evidence of...but has your double flue boiler have any additional insulation under the wooden lagging?

You're right, I missed the opportunity to to include an additional insulation sheet.
But compared to bare brass, even the thin wooden layer should have some insulating effect. And taking the powerful burners into account, heat loss doesn't seem to be an issue anyway.
Finally, I don't care about possible future changes in wood color too much. So what?

"I particularly like the night time snap in the boiler room with those two beautiful BLUE gas flames ...looks like optimum combustion with the white flame body etc"

But something is not correct here in this view....the hottest point of the gas flame will be is approx 25 mm inboard only or am I missing something

All explanations with live steam are a learning curve for us all........

Regner recommends a gap of 7 mm between burner and boiler, so that's how I set it up. I think it's not so much about heating one certain spot of the boiler to maximum heat (unlike siver soldering...), but just to get a good heat input of hot gases into the boiler flues.
And this seems to work quite well, as heating up from cold to 3 Bar took a mere 3 minutes... Not to stress the boiler too much, I will reduce the flame for future steaming up.

[derekwarner_decoy]

Hi PD's...& Moritz quotes.....

'Regner recommends a gap of 7 mm between burner and boiler.........and this seems to work quite well, as heating up from cold to 3 Bar took a mere 3 minutes... Not to stress the boiler too much, I will reduce the flame for future steaming up'

Goodness...3 minutes from cold to 3 Bar steam is surefire pretty good...so my guess is that the night time snap with those two beautiful BLUE gas flames was prior to the Laspe regulator taking control or lowering of the gas pressure etc 

1) insulation in the hull 'under the two beautiful BLUE gas flames ...may be needed'..but also insulation above the burner flame as both radiation & convection of the flame temperature will be an issue in an enclosed hull-cabin structure

2) The condenser..de-oiler..I can see gentle convolutions on the outside diameter but don't understand these?

regards Derek

[Bierjunge]

Hi Derek,

Boy, you're into detail...

I understand that you have noted a 7 mm clearance between the boiler & the burner....but is this 7 mm the distance from the burner face to the boiler face or 7 mm from the burner face to the burner extension tube that protrudes from the boiler face which creates the 7 mm air gap?

I interprete the drawing as 7 mm gap between the plane of the edge of the burner and the plane of the edge of the extended flue.
If you want to have a look yourself: http://www.regner-dampftechnik.de/service/pdf/Betriebsanleitung_Dampfkessel_50620.pdf
It would be easy to play around with diffenet settings, I simply didn't see the need so far.
Btw, Regner's boiler comes with generous superheating. I deliberately omitted this feature and run my engine on saturated steam, following Graham's recommendations in order to get better lubrication.

...so my guess is that the night time snap with those two beautiful BLUE gas flames was prior to the Laspe regulator taking control or lowering of the gas pressure

Umm, no, this is how it looks under full load. The Laspe regulator reacts very fast and precisely: When I open the governor, the flame reacts instantaneously as soon as the engine starts turning.

1) insulation in the hull 'under the two beautiful BLUE gas flames ...may be needed'..but also insulation above the burner flame as both radiation & convection of the flame temperature will be an issue in an enclosed hull-cabin structure

That's why I tried to keep as much empty space around the burners as possible (you will notice how the gas regulator is cramped to the gas tank).
After all, I think it's more a matter of radiation than convectuion, because all air around is sucked in through the boiler flues. For protection of the hull, I hope that a heat reflecting aluminium sheet with an air gap behind will do.
I plan to build the boat according to the version depicted in http://www.servicehistorique.sga.defense.gouv.fr/02fonds-collections/banquedocuments/planbato/planbato/Plans/Vedette%20porte%20torpilles%201889/CAN%20TOR1889PL42.tif where the cockpit is closed by a small deck in front of the boiler, so the burners will be concealed. The compartment under this deck will be reserved for the burners, the small hatch in the deck will remain open for fresh air supply.
If I get problems with trapped heat, I could still leave the deck away.

2) The condenser..de-oiler..I can see gentle convolutions on the outside diameter but don't understand these?

I could now tell something silly about stability against vecuum in the condenser... 
No, the only reason for the convolutions is: That it didn't slip out of your fingers when it still was an oil can. Remember http://www.paddleducks.co.uk/smf/index.php?topic=3245.msg14547#msg14547 ?

Regards, Moritz

[derekwarner_decoy]

Hi PD's.....  ..without detail Moritz.... my world would not exist  & 

Without considerable calculation...it is difficult to imagine the actual free air consumption via the twin burner air intake slots during combustion

Your open board burner/steam tests certainly confirm functionality...

We look forward to the hull build & more......

Oh PS... sorry.....I did read of you original oil can to condenser conversion...just slipped the memory bank 

regards

[Bierjunge]

After several hours of breaking in on the test bench, the drivetrain seems mature enough to think of building the hull.
The only major necessary modification of the plant was to replace the Regner oiler: It was cumbersome to drain, almost impossible to refill, and either had not enough oil volume, or wasted the oil far too fast:
Usually, I had to refill the oiler four times per boiler filling, each time after the engine came close to jamming witch a scraping sound...  , and each time I found the oiler full of clear water with not the slightest trace of oil being left. Because the orifice is not accessible or even visible, there was little I could do except replacing the entire thing.
Now I also went for the Niggel oiler with glass tube, really a thing of beauty, fun to obeserve and dispensing just the right amount of oil. Even better, its package permitted a shorter and straighter exhaust line, and because the oiler can be easily drained from the top, I could fit the flywheel again which I had omitted with the old oiler. I even like the Niggel tube fittings much better than the Regner ones, very precise and easy to solder with their sleeve extension.

Now for the hull, the framework of formers is erected. To be more precise, it's just the positive mould for a future fiberglass hull, so the formers can be solid. It's a great feeling when the threedimensional shape of the hull materialises under your hand for the first time, especially if it's the first hull you build.


Moritz

[kno3]

Nice work Moritz!
The Niggel oiler is beautfully made. I'm using one too in my boat, but chose the model with regulating valve because I wasn't sure how much oil the engine needs.

Why are building the hull of fiberglass and not wood?

[Bierjunge]

Why are building the hull of fiberglass and not wood?

Basically two concerns:
- The package will be quite cramped, the are some spots where there is simply no space for wooden formers or stringers. Btw, the prototype has a steel hull. So maybe a brass hull according to Andy's system could have been an alternative.
- I don't want to jeopardize a wooden hull by the hot oil and water spittings from the engine. And an engine compartment with wooden stringers would be somehow difficult to clean out.

[kno3]

Ok I see and this makes sense. I don't know which brass hull you are referring to. Do you have a link?

[derekwarner_decoy]

Hi PD's.......Moritz....from your posting April 14....... I see the elevation view of the vessel & internals .....& an isometric view of the boiler superimposed over the plan view

But from your May 25 posting....I cannot see where the converted OIL can to deoiler waste water tank will fit within the beam of the the actual vessel

But anyway ......the machinary is looking super  .....regards Derek 

[Bierjunge]

I don't know which brass hull you are referring to. Do you have a link?

I was referring to Andy's fabulous Ammersee steamers, described in http://www.paddleducks.co.uk/smf/index.php?topic=3429.0

....from your posting April 14....... I see the elevation view of the vessel & internals .....& an isometric view of the boiler superimposed over the plan view
But from your May 25 posting....I cannot see where the converted OIL can to deoiler waste water tank will fit within the beam of the the actual vessel

Don't wory, Derek, it fits. In fact, one of my motivations of the test bench/board setup was to make sure that packaging is feasible.

Best regards, Moritz

[Engineman]

So maybe a brass hull according to Andy's system could have been an alternative.

Upto my experience the brass hull shall be the best solution for the particular (steam) application. Not only because of better weight and rigidity - soldering in general is much better than gluing, especially for small fittings. Showing the plating belts should be also a very neat detail for the model.

Anyways, absolutely stunning project Gretzschel!!! Please keep us informed about the progress!