Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[kiwimodeller]

Ian, Yours may not be the first R/C Flash Steamer but it shore as heck is by far the most sophisticated and controllable. If you cannot find the article about Ooyah send me a P M with your address. I do not have the facility to scan and email it easily but would be happy to copy it and send it by snail mail. Cheers, Ian V.

[Martin (Admin)]

Here she is seen at Wicksteed over the Mayhem weekend...

[flashtwo]

Hi,

Thankyou Martin for posting the maiden voyage photos of the "Vital Byte", it is very much appreciated.

Yesterday "Vital Byte" made first steam on the Blackheath Pond, which, in flash steam circles, is a famous for it association with flash steam experimenting over several generations.

Having overcome the pond access problem of its inclined sides (SteamboatPhil gave me some welly - i.e. he lent me a spare pair), Vital Byte was steamed up (no problem this time with too high a gas cylinder pressure) and off it went around the pond.

I experimented with various superheat (software) settings and got up to a good speed. Again a lot of interest was shown at the pond side by Blackheath Club members and the public.

I had the honour of demonstrating the boat and its control system to Alan Rayman, the co-author of "Experimental Flash Steam". He said, considering the basic hull shape, that the performance was quite adequate for its displacement of 70lbs (32kg), I think the consensus was that I should now build a proper hull to get an even better performance. Alan also suggested doubling the size of the displacement oil lubricator, considering the long runs that I was doing, or even fit a mechanical lubricator.

Total gas consumption this time, including start-up, was 111grams (I must start timing the runs). I'm getting two good days out with one 460gram cylinder and that works out to about £2-60 per day for the gas.

One software change I'm going to make is to give the servo driven indicator on the "bridge" the ability to display boiler pressure or gas cylinder pressure. I can then use it as a fuel gauge to get the most out of each cylinder without ending up with lots of partially emptied ones, i.e. if i see the gas pressure dropping well below 100kPa (14psi) I will then think about bringing the boat back to shore.

Ian.

[gondolier88]

Hi Ian,

Whats stopping this tech' being applied to full size flash steam plants- the auto software I mean- not so much the RC 

Greg

[flashtwo]

Hi Greg,

That's food for thought.

If the full size boat was gas fired and had an electric feed pump, then perhaps a higher torque gas servo and a higher rated ESC for the pump motor would be the main changes. A thermocouple would have to be installed to measure the steam temperature and a pressure transmitter for the boiler pressure. There would be no real difference in price between a full size or model boat control system.

If there is only an engine driven mechanical pump, then some means would be required to measure and control the feed flow by leaking off excessive feed. If the firing is with solid fuel then electric fans / air dampers would have to be employed to control the heat input, though the control would be quite sluggish compared with gas/oil burners.

The control system is designed to be tuned for different rates of heating, i.e. larger burners and more boiler mass.

I'm afraid that most traditional mechanical control systems for flash boilers were at their limit - they could not be easily modified for the best performance nor tuned for the best response.

With the software based system, there are lots of "features" like over-firing protection on start-up, high temperature and high pressure shut down of the gas valve, acceleration modes and also the ability to see whats going on regarding pressures, temperatures, feed flow and engine speed to mention just a few.

I suppose it depends on the boat owner - does he/she want to experiment or stick with the traditional methods and will it make the running easier.

The model boat is perhaps a useful tool for developing a system for a full size boat - modelling in the true sense of the word.

I'd be interested in any further thoughts you may have.

All the best,

Ian.

[flashtwo]

Greetings All.......

I've just installed the latest software so that the boat times itself and displays the run time in minutes (saves me remembering to start/stop timing).

The computer now also records and displays the following data:-

a) Maximum engine RPM attained.
b) Maximum feed flow.
c) Maximum boiler pressure
d) Maximum steam temperature.
e) Maximum economiser outlet temperature.
f)  Maximum gas cylinder pressure....
g) ...... and Minimum gas cylinder pressure.
h) Total and Run engine revolutions (not RPM).
i)  Total and Run pumping strokes.

The servo driven mechanical pointer can now be selected to display the boiler pressure for start-up conditions and then gas cylinder pressure for cruising, so acting as a fuel gauge.

Now I know why its called software - its so flexible!

Must get the Vital Byte back on the pond to see if the latast software works.

Ian.

[flashtwo]

Hi,

Vital Byte's skipper screws it up!

Vital Byte's latest voyage was down at Dover at the weekend (not in the Channel but at Kearsney Abbey!). The Model Boat Association Dover had its annual open day on Sunday and the oportunity was taken to do some test runs and play around with the control settings.

Questions were naturally asked about boiler certificates etc., but it was soon understood that none were required for a flash boiler.

The first run was going fine for the first 15 minutes, until Richard from the Maidstone Cygnets MBC made the remark that the response was very impressive - that was the death knell!   Vital Byte was going at Warp Speed 9, when it became apparent that steering was not what it had once been - "She's not answering the helm Cap'n" cried out an imaginary Scotty from the engine room!

As we were literally heading to the rocks something had to be done fast - luckily the engine went into reverse, VB slowed down and Alan Poole, of the Dover MBA, quickly organised a rescue mission. With the use of other members boats, VB was nudged to the shore. Thanks all round.

A quick examination revealed that the servo to rudder adaptor had become loose ( all that showing off of the response!); with a quick application of the screw driver, VB was soon back out on the pond, but without the skipper throwing the rudder all over the place.

VB did two long runs - one of 31 another of 44 minutes, the timing being done by VB itself. The new software features worked (except for total revs for some reason) and maximum and minimun parameters were logged. Gas consumption was 4.0g/min for the first run and 4.5 for the second run.

I did alter the feed water controller for the second run a bit too much and VB stalled out in the middle of the pond and became stationary - another rescue mission was offered by club members, but this became a test of its automatic recovery mode of operation (the Mars Rovers have nothing on this babe!). After a few minutes a wisp of steam was seen to rise and slowly VB came back to life.

I managed to capture some valuble data and will also now incorporate an average RPM reading. The maximum RPM achieved was 570 although I'm aiming for 800 which is what I obtained from Malcolm Beak's equations.

At the moment I'm trying to understand where the limitations are - gas nozzle size? gas consumption? heating area? etc.

Thanks once more to Dover MBA for their help and interest.

Ian.

p.s. One secret development I've not mentioned is the Carbon Capture environmental feature of the boiler. This was secretly photographed by Alan Poole of Dover MBA and I have obtained an exclusive  copy for Mayhemers! The green carbon capture spheres (CCSs) are collected from the pond after the experimental runs! (see attached photograph).

[flashtwo]

Hi Mayhemers,

Just an update on the latest voyages of the Vital Byte.

VB has had a few mechanical and software problems over the last two weekends on the Cygnets Model boat Club venue at Mote Park, Maidstone.

VB had a run of 18 minutes to use up gas in a partly used cylinder and achieved 588RPM max with a gas consumption of 4.3g/min and then, with a fresh cylinder, a 53 minute run at 593RPM max and 3.7g/min consumption. Unfortunately the "A" pump motor blew its fuse and I had to swop over to "B" pump between the two runs.

Inspecting the pump later, I found that the ram was tight because the pump body had become slightly misaligned. With the help of a piece of SteamboatPhil's kindly supplied shim, the body was realigned and was tested OK.

The software recording the engine revolutions (and average RPM) was not working and was found to be due to part of the calculation taking place during the speed probe pulse. The calculation was moved in the software to occur after the pulse and the data is now being recorded properly.

Previously, at Kearsney Abbey, I had been monitoring the ambient temperature of the bow compartment where the gas cylinder is located with a max/min thermometer. Well, as reported elsewhere on this forum, the thermometer melted and it contents disappeared! Therefore, I have made a ventilation hole and an aluminium shield directing the heat away from the cylinder area.

The ongoing problems of putting the engine into reverse were traced to the drive-end "B" cylinder valve timing and also the "A" piston bottoming out, causing stiffness at bottom dead centre.

Having sorted all of the above problems, VB had another outing to Mote Park last Sunday - and what a disaster it was!

I spent the best part of an hour chatting to people about the boat and its computer before I attempted to put her on the water. The pump jammed again and the computer overheated due to the sun shining through its clear plastic cover (it was acting like a greenhouse) whilst it was on the shore. No voyage on that outing.

This time it was found that the pump was fine but the commutator end of its electric motor had become loose and resulted in loss of output. The gas control chip had failed on the steam temperature input of all things. A new motor and gear box was fitted and tested and a new PIC chip fitted and downloaded with the control program.

A fan was fitted to the computer housing for use on very hot days (you can tell this developed in the winter!) and the pump control software was modified to automatically switch to the standby feed pump within 6 seconds of the main pump failing and also a gas valve shut instruction was added if both pumps failed.

Today VB managed a decent run at last. She moved effortlessly between forward and reverse, maximum bow compartment temp was 28degC instead of 50plus and the pumps worked ok. Max RPM was 580 and average was 334. The engine was ticking over at about 50kPa (8psi).

On the water at the same time was the Cygnets 50th anniversary build of HMS Kent, type 23 destroyer. She was having a shake-down cruise before her epic voyage between Tonbridge and Allington Locks, via Maidstone, on the River Medway next Saturday 11th July ( visit http://www.cygnetsmbc.com/ for details of the day). The 12 foot model just cut through the water like a knife through butter, a magnificent achievement.

Vital Byte will be exhibited at the Guildford Steam Rally on the 18th/19th July, I hope to see some Mayhemers there.

Ian.

Below - the latest VB photo.

[SteamboatPhil]

Great stuff Ian, oh the joys of flash steam. I have just re-done the fuel pump on my flash steamer, plus a new flame tube (I'm using vapourising petrol not gas like Ian)
Got a few good runs in today (in fact I won the steering event), also picked up a lot of weed. Keep going Ian (then I can pinch your data)   

[flashtwo]

Hi,

VB made it to the Guildford Steam Rally in one piece and was set up outside the marquee (it allowed room for four other smaller boats to be inside!) on it very own display stand. This was a bonus since it reduced the amount of carrying to and from the demo pool, though not such when it rained!

The demo pool was just deep enough for display, though, and being only 20x20 feet square, it presented a fine opportunity for learning to manoeuvre in confined waters. Full use was made of the reversing gear, now that it is reliable. About six demo runs were made over the weekend.

Although the pool size prevented maximum performance, it did allow the visitors closer inspection of the engine and its control system display, whilst in operation and also the method of raising steam quickly with the flash boiler compared with the more conventional plant.

With VB on static display, the boiler heatshield and control compartment covers were removed to allow the flash coil and computer to be viewed. Again the visitor response was as varied as their own experience. Some appreciated the boiler simplicity and just walked away on seeing the computer,  whereas others were very knowledgable on control theory and others on the use of PIC controllers.

It was an excellent oportunity to compare the flash boiler technology and it computer controls with a conventional steam plant on display in the marquee. The plant was to power a 82lb displacement tug also using a Stuart  D10 and running with a 4.25 inch prop. This was very close to the VB arrangement although there was no comparison in the hull design!

Chris the owner, and Guildford Club member, kindly took me through his design and build documentation book that he had on display. It was a very profesional comprehensive engineering document with all the materials lists and stress calculations and every thing you would want to know on how to construct the conventional boiler.

Both of us had used Malcolm Beak's calculation method, but the only trouble was that Chris had used imperial and I metric units, so making comparisons difficult (a certain  American Mars probe comes to mind!).

Chris described his boiler construction method and the difficulties that he had overcome. I came to the conclusion that I had transferred the effort of making steam from a boiler making to a software exercise. The flash boiler coil only took a couple of hours to wind and had two silver soldered connections,  but the control system  took many, many hours of work -  the complete opposite of the conventional approach. Chris's tug and marine plant have been built to a very high standard and he hopes to demonstrate it at next years rally.

A few Mayhemers turned up. Logoman with Logowife and Logokids were there, plus a few that that had seen the plant at the Ally Pally in January before VB was built. Their interest was very much appreciated.

Many thanks to Bryan Finch of the Guildford Club, who organised the boating section and greatly assisted me in carrying the VB back and forth to the demo pool. He has encouraged me to build a lighter boat!

VB will be at the "Boats on the Mote" Cygnets Club open day at Mote Park, Maidstone this coming Sunday. I shall be carry out a few experiments with VB.

Ian.

[gondolier88]

Hi flashtwo,

Good to hear the different responses of people to the controls- your a pioneer in the model boat world mate!

Just need a hull to match your electrickery now....!!!!!

Greg

[Dave_Sohlstrom]

Ian

I have been watching your progress from my side of the pond. Very interesting. Would it be possable to fit one of your computers to a conventional water tube marine model boiler at 100 psi and about 400 SQ In heating surface. boiler will be running a long stroke engine on a model stern wheel tug. search Steam Tug Portland.

Dave

[gondolier88]

Hi Dave,

Good to have you here mate. What are you wanting to be controlled by the computer? Do you want a crewless engineroom or secondary emergency control?

Greg

[flashtwo]

Hi Dave,

Thank you very much for your interest.

The conventional boiler is best to suited to a method of water level control, which would use an electric pump to top up the boiler when necessary. The level can be detected in various ways - optical through the level sight glass or via a resistance / capacitance probe within the boiler shell.

The flash boiler requires a different system where the electric pumps maintain a desired flow independant of the boiler pressure.

Also, the conventional boiler needs to control its steam pressure at a constant value by adjusting the fuel supply e.g. via a servo controlled gas valve. Normally this is achieved in a model by measuring the steam temperature with a thermistor, since steam saturation temperature is directly related to pressure. The thermistor, being a resistance device, would then be part of a voltage bridge circuit which would ultimately control a relay that operates the electric pump.

The flash boiler doesn't bother to control pressure, just steam temperature - aha! I hear you say, isn't this the same as the conventional where the pressure is the same as the temperature - well, no - if the steam pipe was open ended, for example, the gas valve would open to maximum trying to raise pressure, but would just overheat the steam (perhaps to 400degC or more) and stress the engine and piston seals.

My computer could be reprogrammed to control a conventional boiler, but it would a bit of an overkill.

I hope this not teaching grandmother to suck eggs, but the flash control is totally different from conventional boiler controls.

Let me know if you require any additional info and I will try and comply.

Ian.

[Dave_Sohlstrom]

Greg

Sorry for delay. Changes at work will put me out of work 15 months earlier than planed. We are crunching numbers now and it looks like we can make it the 8 months till I'm 62.
The Stern Wheeler I am looking to model is the Steam Tug Portland. She was retired from active ship handleing duties in1981. She is still aflot and they steam her a couple of times a year. Last year going up the Columbia river for a race she lost steering and damaged her rudders and paddle wheel. I was able to get a lot of pics while she was in dry dock. She is 210' LOA and 42' wide. The model at 3/8"=1' will be close to 7 ' LOA and nearly 16" wide. Engine will be 3/4" bore and 3 3/8" stroke. Will be full RC control and have an 8' barge with extra fuel and water for her to push around. I have not been able to find qualified marine engineers in 1/32 scale that will work for free so I will have to put automated controls on the boiler so I do not run out of water or steam in the middle of the pond.

Ian

Thanks for the reply. I will be researching how to best control water level and pressure. I expect the boiler to be a fast steamer with the number of water tubes it will have compared to the water volume that it will have.
 
I will continue to keep an eye on your project and will probably ask more questions.


Dave

[gondolier88]

Hi Dave,

Great project, I hope you see it through to the end. Have you got a pic to show us?

At that size you would have enough room to have mechanical control- ie. a feed pump acting off the engine through a bypass controlled by a water sensor on the water gauge with an auto boiler pressure gas regulator controlling the burner.

Greg

[kiwimodeller]

Dave, sounds like a great project, don't forget that we expect a fully illustrated ongoing post as you do the build, just so we have the pleasure of nitpicking any little mistakes you make. Just kidding! But we would all like to see the build. I take it from your description of the engines that you are going to build them as direct acting on the paddlewheel shaft? I am hoping to do the same when I build a model of a New Zealand sternwheeler but it will not be at such a large scale. I am looking at 1:24 and two cylinders of about 3/8" bore and 2" stroke. I am hoping somebody else has or will sort out all the problems before I get started. Cheers, Ian V

[gondolier88]

Hi Ian,

I am looking at 1:24 and two cylinders of about 3/8" bore and 2" stroke.

Very strange cylinder  size- any reason for this in particular? You'd be lucky to get any workable rev's off that- I know sternwheelers don't need a lot of rev's anyway- but I have a feeling that would be excessively slow.

Greg

[Dave_Sohlstrom]

I have to agree with Greg. You are building at 1/2"=1' at 1:24. That would make the real engine 9" bore by 4' stroke seems small for that scale. Portland full size engine is 26" bore and 9' stroke. How long is the full size vessel you are modeling. Portland is 210 feet long, she is a big tug.

Dave

[kiwimodeller]

The original was just over 100ft so not large by American sternwheeler standards. I am not yet sure of the original bore and stroke, still waiting on the plans but the idea of the long stroke was to give good torque and sufficient leverage at the wheelshaft by having the big end a reasonable distance from the centre of the shaft. I read somewhere that small bore long stroke steam engines were slow revving but produced good torque and were still economical on steam as the long stroke utilised all the expansive properties of the steam. Theory of course is not always right and I am ready to change my ideas, in fact it would be easier to have a shorter stroke engine, but would I get away with that without having any sort of gear reduction between the engine and the shaft? I am always happy to blame someone else's ideas when things dont work!

[Dave_Sohlstrom]

Ian

Do you have the name of the vessel you are going to model. It may be possable to find information on line.

Dave

[gondolier88]

You wouldn't need anywhere near the torque required fullsize- remember torque is a square and weight is cubed- go for a shorter stroke- easier to steam, easier to start, and should you need it on the pond- a burst of speed.

Also you could always utilise commercially available stationary mill engine cylinders.

Just a thought.

Greg

[kiwimodeller]

Dave, the vessel is called Manuwai, a Whanganui River (New Zealand) sternwheeler built in kitset form by Yarrows. Model plans are in the process of being drawn up. When I said I did not have the original engine dimensions I meant they have not arrived to me yet but I know they are available and will arrive, there is considerable information about her available.
Greg, I agree it would be much easier to use a shorter stroke and utilise commercial cylinders from someone like John at The Steam Chest who has a great range of engine casting kits that I have been eyeing up and I will do so as long as I can be convinced that they will have enough grunt. We had the discussion at a club day today and the older members are definitely of the opinion that small bore, long stroke engines operating on fairly high pressure and using all the expansive power of high pressure steam will do the job best. Other members, like you are saying that the greater power of more piston area will be more responsive and that I will not need high pressure. It seems quite possible that both would work, the first with high pressure but using a lower volume of steam, the second option using lower pressure but needing a fairly big boiler to make a high volume of steam. It may well be that I need to suck it and see, fortunately it will be a few months before I finish present projects and get on to this one so I have time to read up and canvas opinions on forums like this. Thanks for the input from both of you. Cheers, Ian.

[kiwi]

Hi Ian,
Just for the record
ps Manuwai had a locomotive type boiler rated at 160 lb. (at 140ib propelled the boat at 11.5 knots max speed ), built by Yarrows of London.
And mounted near the bow, consuming 6.5cwt coal per hour from two 3ton coal bunkers either side of the boiler.
Two engines at stern, horizontal with 10.5" bore and 30" stroke, with stephensons link fitted. Operated by telegraph from the bridge. Main steam pipes ran along the underside of the upper deck.
These drove a stern wheel of 10ft dia x 11'-9" width fitted with 10 floats of 9" wide English Elm.
Hull was of galvanised Seimens' mild steel, divide into 7 watertight compartments, each with its ejection pump. On the foredeck was a small double cylinder steam winch for hauling up rapids.

Drawings progressing well, and a friend in the trade is looking at making a fibre-glass hull if your interested, in the size your considering.
kiwi

[kiwimodeller]

Harry, you are as usual a lifesaver and tell that man that I will give my first born son (I've been trying to get rid of him for 30 years) for a glass hull in the right scale  Perhaps you could ask him nicely to increase the depth of the hull to give a little extra displacement to carry heavier (in scale proportions) boilers etc? I have already put aside a nice 9" by 4" boiler which looks the part to try first and am gathering parts and info. Todays effort was to go through my collection of 1940's/50's Model Ships and Powerboats and Voila! I found an Edgar Westbury treatise which discusses engines for different applications and says, in part, "the exception being engines for paddle steamers which, if connected directly to the wheel shaft need to be of small bore and long stroke. Shorter stroke engines need a bevel gear or other reduction to work satisfactorily when driving paddle wheels which rotate slowly". I knew I got the idea of long stroke engines somewhere and this was probably where. Cheers, Ian.

[flashtwo]

Hi all Mayhemers,

At last Vital Byte is back on the water (after sorting out new kitchen/university etc).

Since its last run at Ramsgate, it was apparent that no further software mods were going to improve the performance, so I reconsidered the boiler coil surface area.

In my original calculations I had estimated the surface area of the fire/copper interface rather than the copper/water interface the values being 138 and 84 sq.inches respectively. Obviously the 84 sq.inches was much to small for the D10 engine, so I've rewound and experimented with a number of coils.

The original was 5 metres of 1/4inch O.D. 18 swg copper and I have wound three additional coils  of 7 metres of 1/4inch 20 swg (142 sq.inches approx), 9 metres of 3/16inch 22 swg (149 sq.inches), and finally 15 metres of 3/16inch 22swg (240 sq.inches), experimenting with each of the coils in V.B. on the test pond (hasn't the price of copper gone up!).

I managed to get all 15 metres of the 3/16inch into the original boiler casing by winding the coil into three layers. It took an hour and three quarters to wind the coil (including a joint to connect the 10 and 5 metres sections together), turn two adaptors on the lathe and fit it in the boat.

The other change to V.B. is the use of a five inch prop, with the proper blade twist, kindly on loan from Malcolm Beak.

Today I steamed V.B. down at Mote Park, Maidstone and she performed extremely well with the 15 metre coil, showing a very powerful bow wave. The hull wave crested at the bow, midway and stern.

She had two runs of 28 and 38 minutes, RPM peaked at 610 and averaged 394. On both the runs the gas consumption was 4grams/minute. The acceleration was very good.

The gas cylinder pressure was monitored. It started of at 2.5bar, which obviously gave the best performance, and was still perfoming well when the gas supply was down to 0.6bar.

Well, I've run out of ideas now to improve what is now a very satisfactory performance, other than putting the plant into a proper hull.

On to the next project - a steam jet powered boat?

Ian

[kiwimodeller]

A steam turbine pulling 35,000 revs would sound good! cheers, Ian 2

[gondolier88]

Hi Ian(s),

Turbine very interesting suggestion- have you seen the Tesla Turbine- kind of a percussive turbine using flat discs- but the 10inch(?) model produced around 30HP- imagine if you could use ultra-thin blue steel discs around 1.5inch Dia. running around 30,000RPM- drive through a half reduction gearbox to give useable and powerful engine.

Also- as you obviously like an experiment- have you seen the Brotan-Defner loco type boiler? Basically an efficient 3 drum watertube boiler forms the firebox, the top drum ,however, is joined to the top of a sloping barrelled conventional locomotive firetube boiler- having a tubeplate at either end though. This mean that at the point of the most heat- the firebox- you have extremely efficient heat transfer- massive surface area, low water content, fantastic water circulation- then the firetubed barrel uses the cooler gasses at a slower speed- extracting the useful heat left. The bottom drums of the watertube boiler are both connected to the barrel by extension tubes curving upto the bottom of the barrel giving increased water circulation.

Steam is taken off the top of the barrel slope or the top drum of the firebox- the thing is the variables with this boiler are numerous- tube diameter, number of tubes, length of tubes on the water tube side- barrel diameter, firetube length, firetube diameter barrel length- also a superheater of the Schmidt type could be fitted (the same type as fitted to the last types of BR express steam locos).

Basically a really developable boiler, could be made super heat efficient and also an interesting engineering project, something to thimk about.

Wikipedia and Google bring up results if you search Brotan boiler and Brotan-Defner boiler.

Greg

[flashtwo]

Thanks for your ideas guys - they're much appreciated.

I was actually thinking of building on my flash steam boiler experience and having a zero reving "engine", i.e. a pure jet with no moving parts apart from the feed water pump.

The ultimate aim is a steam powered Bluebird K7 (but with better high speed stability!) - wishful thinking perhaps, but I might learn something new on the way.

I've just started on the feed pump and I shall be using the boiler coils from the Vital Byte experiments.

The Vital Byte will still be in the frame though, since I want to reduce the computer size and extend the endurance. Currently VB is run time limited by the engine exhaust oil trap filling up and the displacement lubricator becoming empty. At a gas consumption of 4grams/minute, the 460grams in the gas cylinder, fuel supply is not a limit for extended running.

One question I have for those with conventional boilers is that when the water level drops in the boiler, does the heating surface area between the copper and water reduce thus affecting the performance of the boiler and engine and is it noticable?

Ian

[kiwimodeller]

Ian, the theory seems to be that with the common types of comercially made boilers available a vertical boiler is more affected by loss of heating area in contact with the water as the level drops than is a horizontal one. A horizontal single flue boiler with cross tubes in the flue would have to be down pretty low before there was a noticeable amount of the heating surface area not in contact with water. In my limited experience other factors such as the drop in gas pressure due to the drop in gas cylinder temperature have far more noticeable effect on the performance of commercial model boiler setups. Cheers, Ian V.

[gondolier88]

Hi Flashtwo,

Steam powered K7 isn't too much of a far-fetched idea- in 2007(?) a flash steam powered hydroplane was entered into the Coniston Water Speed Trials- however although it had worked really well on experimental runs, on the day it failed to perform.

Greg

[SteamboatPhil]

The full size flash steam hydroplane will be returning to Coniston this year to have another bash at the record. I gather that John has ironed out all the bugs he had in 07.
I will keep you up to date on his progress.

[flashtwo]

Phil,
Has the Coniston flash steam hydroplane got a website - I'm intrigued. Regarding Vital Byte, I've got the feeling, since now I've 45 foot of tubing, that the traditional flash steam boiler really over-fires the boiler to achieve red hot coils and true flashing off of the steam rather than a boiling off. Do you calculate steam production in the traditional way of surface area of the copper/water interface or is it more a matter of burning as much fuel as possible? The point is my plant seems to be so tame (though still very effective) compared with the performance of your straight runners and the tethered variety or are they completely different animals.


Last Saturday, I remade the D10's slide valve push rods, since the originals had too much vertical play in them for accurate valve timing. On Sunday at Mote Park, the test run was a total failure due to the slide valves themselves not seating, consequently letting by all the steam. (club member Richard was there again, strangely coincident with major problems with VB!)

I discovered that, although the vertical slack had been eliminated, there was not enough clearance between the slide valves and the adjusting nuts, causing them to bind. By use of a fine file, enough clearance was made, timing reset and the slide valve seating was tested by applying suction to the respective exhaust port.

VB was run in the test tank and peaked at 642RPM and averaged 465RPM over an 11 minute run. Ready now for another run on the lake.

With regard to hull speed, I understand that is achieved when there is an equal  bow and a stern wave with a dip halfway along the waterline. If there is a wave halfway along the waterline does that mean it is going at half hull speed, or is it an indication of an efficient mode of running?

Ian G.

[gondolier88]

Hi Ian G,

Wow you are getting into hull design as well as experimental steam eh!!!

Ok, a steam hull should always have the most efficient hull design possible. Indications of efficiency are-

- Little or no 'hull wave'- the bigger the wave the more the water is being pushed out of the way as opposed to being 'run over'.
- Bow lift- means displacement is in the right area- if the bow cuts in and down the displacement is dragging and needs more power.
- Stern stays bouyant at hull speed- the more it sinks the more wake is made and this just wastes power.

These go for displacement hulls only of course.

These are the two most efficient hulls in the SBA...currently !

1- Arlette- 31ft single chine plywood with loco boiler and single cylinder thornycroft engine 3 3/4" x 5"(?)
2- Oberon- 29ft strip plank cedar hull, 3-drum LIFU boiler with 2 1/2" + 5" x 4" LIFU compound.

In the pics they are both running at full speed- this is Arlette- 16mph and Oberon- 14mph- both engines run around 600-700 rpm- do the maths with the engine's power and you can see how efficient these boats are.

Greg

[kno3]

Where are the pics?