Re: Message from a very 'newbie' (or Flash Steam)

[FlashTwo]

Hi,

I have successfully constructed a flash boiler, which is being used to steam a Stuart D10 machined from the castings kit. The D10 is connected to a small DC generator acting as a controllable load.

The entire system is controlled by a home built and programmed control system based on PIC micro-controllers. The control system receives the engine RPM demand signal from the radio control receiver and controls the electric feed pump and servo-controlled gas valve. The actual engine speed is measured and the feed pumps and gas valve are automatically adjusted to maintain the required speed.

I have just perfected the method of starting (and stopping!) the engine and find the RPM and temperature controls do a find job - good speed change response and steam temperature controlled well below 200C. No exessively high pressure or temperatures as experienced with the old classic flash steam boats.

To give an idea of the software complexity, it has taken me at least five times the hours to write the software as it did to build the boiler and engine - not for the faint-hearted. Being a software based control system it is very easy to duplicate additional systems.

My next step is to build a simple hull (5 to 6ft) and get the lot onto the lake for additional testing.

I will keep you posted.
All the best -Ian

[Red_Hamish]

Hello  all, Ian an excellent and informative post from a dedicated engineer. It takes real enthusiasm and passion to  complete such a complex design to this stage.

cheers

Jim

[Eddy Matthews]

Goy any photographs Ian? I'm sure a lot of our steam guys would find it interesting to look at...

Regards
Eddy

[steamboatmodel]

Hi Ian,
Which PIC micro?
Regards,
Gerald

[FlashTwo]

Hi,
Thankyou for your enthusiastic responses.

The control system uses a number of MicroChip 16F877 PICs selected because they have a good number of analogue inputs and digital inputs/outputs and a flash memory (hence my login name flashtwo - flash steam + flash memory). The analogue inputs receive the pressures and temperatures signals of the development steam plant, which are used for control and indication. The digitals are used to drive servos and the Electronic Speed Controllers (ESCs) for the electric water pumps. The PICs also drive an LCD display and control box which is removed when it is not required for development.

The actual boiler comprises 5 metres, 1/4" copper pipe doubled coiled into a 10" long by 4" diameter horizontal stainless steel enclosure; this was based on the designs in the book 'Experimental Flash Steam' by Benson & Rayman.

The steam outlet pipe connects to a small manifold from which the pressure and temperature are measured. The manifold also has a small safety valve set at 7Bar. The steam then goes directly to the Stuart D10 without the need of a regulating/throttle valve, steam flow being controlled purely by the feed pumps (I am using two for anticipated reliablity out on the lake) and the gas valve.

The boiler stack contains a metre or so of 3/16" copper tube acting as an economiser which can raise the feed water by about 50C.

The boiler and engine can be running from cold in a couple of minutes, since the boiler tube only contains about 35 milli-litres (yes 35ml!) of water and hence the need of a reliable feed pump. The small thermal inertia of the boiler is one of the reasons why a steam regulator is not required, since the boiler responds very quickly to the gas valve movement.

The control system is built into a slim box and is designed to be transferable between models since it plugs into a simple interface board which resides on each model boat. Currently the controller contains six 16F877s - one of them is redundent and three of them can be replaced with smaller/cheaper PICs; of the remaining pair, one controls the gas valve and the other the two water pumps.

I shall post some photographs once I've tidied the workbench and mopped up the steam oil!

All the best
Ian.

[kno3]

Your boiler control system seems very interesting. I'd love to see some pictures too.

[derekwarner_decoy]

OK PD's....I will send all of my left over 5 cent coins to "Life Line" here in OZ if .....All the best Ian. shows the colour of his thoughts...............

[steamboatmodel]

Hi Ian,
It sounds fantastic. Could you post the schematics and source code for the control unit too?
Regards,
Gerald.
PS I have bought the PIC kit 2 programmer and just started playing with it.

[FlashTwo]

Dear Derek,

(I've been looking forward to this moment!)

Please send lots and lots of your left over 5 cent coins (and dollars) to "Life Line"  ( http://www.lifeline.org.au/support_us/donate ).

The flash steam computer controlled test vessel, the "Vital Byte", made it's maiden voyage on Saturday
at the "Model Boat Meyhem" meeting here in England (see their website http://www.modelboatmayhem.co.uk/forum/index.php?topic=15817.25 for my account of the maiden voyage).

It was very successful and will now will tuned up to "water skiing" performance (not at 32kg displacement though!).

Thanks for the challenge!

All the very best

Ian.

[derekwarner_decoy]

Hi all......a quote from Ian.......

"I had trouble starting since the new gas cylinder pressure was 3.4bar (the cylinder had been in the car under the hot sun)"

Congratulations of the maiden voyage working so well & full credit to you ....I have trouble with our new kitchen microwave .......gone are the days of a knob to set the temperature & a dial to determine the minutes.......

 ,,,,,,now you need a Degree in computing science to boil water  ......Derek

[Hankwilliams]

Hi Ian,

I would like to see some pictures of the flash steam boiler and the boat!

Tom

[FlashTwo]

Hi Tom,

I had enough on my plate preparing for the maiden voyage to remember to take a camera to the event, but it was recorded by other people.

On the website http://www.john-dowd.co.uk/  there is a YouTube video and I'm chatting about the boat and controls from 2mins 11secs into the video.

If you go to the website http://www.modelboatmayhem.co.uk/forum/index.php?topic=15817.0 , you will see photographs of the steam plant in various stages of development. You will have to register to gain access to the photos and I would post them on this forum if it was a bit easier to do.

Derek - you have to understand that the plant controls were developed in our winter when the shed temperatures were around 2degC and the aim was to maintain gas burner control under those conditions. It was very hot last Sunday, around 21degC, and even hotter in the car! I shall have "Australianise" the software for higher ambient, especially for all this global warming thats predicted. Have you posted your donations yet? Thanks for your congrats though - its very much appreciated.

cheers

Ian.

 

[Eddy Matthews]

I would post them on this forum if it was a bit easier to do.

Posting photos on here is exactly the same as Mayhem as we both use the same forum software...... Takes all of a few seconds to post an image....

[FlashTwo]

Thanks Eddy - that makes life much easier.

Ian G.

[FlashTwo]

Hi,

Here are few photos taken by Alan Poole of the Dover Model Boats Association last weekend with the above steam plant mounted in the experimental boat the "Vital Byte".

Ian.