Firstly, thank you for your comments on the build so far. slow but steady progress has been made since last month, but the hot weather hasn't helped much with my energy levels.
After playing around with the battery position , the idea of using a 12v sla was abandoned due to the tight fit & some packs of 10 AA nimh 2600mah cells were acquired. these are considerably easier to fit & remove especially when the boiler is hot. A battery pack mounting plate was made up using 2mm plastic card & glued into position. The inside of the hull has been rubbed down, primed & painted using 2 pack black, which was matted down 50%. The hull was then set aside for a week to allow things to harden fully.
The old boiler ( the 1 for the boat, not swmbo !!!) was looking a but sorry for its self, although previous inspection & pressure testing had shown it to be in good condition. A new piece of copper pipe was silver soldered on to the boiler to allow the fitting of the flue. this was actually a 22 mm straight pipe coupling suitable altered, & the whole boiler was placed in the pickle solution (citric acid & water from the chemists), that had been made up for cleaning the pipe work, for a few days to clean everything up. Then the boiler was steam cleaned, rubbed down with fine paper & painted with heat resistant matt black, prior to lagging. The original plan was to cover the boiler in walnut strips, but there was a bundle of suitably sized spruce just sitting there , so i tried this to see what it looked like. maybe with some stain it will look OK , but I'm not convinced.
Many an hour was passed sitting in front of the TV filling, sanding & polishing the old & new steam fittings, along with the pipe work.at this point it was decided to paint the fittings in the same colour as the engine to try to pull everything together colour wise. All parts were then fitted in to the hull to check fit & finalise what to do with the gas tank.
After much thought, a brass plate was made up to mount the gas tank on, this sits above the condenser ( i keep referring to it as a condenser, but in reality its just an oil & water trap to try to clean the steam before its ejected out of the stack) allowing a 3mm gap between the condenser & the plate. The hope is this will transfer sufficient heat to the tank to combat any cooling effects the gas expansion has on it. theres sufficient clearance to put insulation material between the 2 if too much heat transfered, or if it proves in effective, some shims can be inserted to allow full contact between the surfaces. Altough I believe theres an MPBA ruling that doesn't allow direct heating of gas tanks, so its down to trial & error to see whats best. The mounting plate will facilitate easy removal of the gas tank for filling, so for now will avoid on board refilling, but may opt for this at a later date.Unfortunately the gas pipe knurled nut is a 1/4 x 32 tpi thread & the gas tank is a 1/4 x 40 tpi thread, so the gas tank still isn't connected. Ideally a knurlled nut of 1/4 x 40 would be the easiest way out but i haven't found anyone selling them so i need to get 1 manufactured for me.
The only other engineering part left is the stack, this needs to be bent to fit the superstructure. The superstructure needs modifying first to allow the boiler flue to pass in to the funnel, so its time to start cutting holes in the model, & i have been dreading this part most of all !!!. While on the subject of the superstructure. none of the cowl vents are hollow & none of the windows & vents are open either, so there plenty of cutting about to be done, but thats getting left for a while or at least until I work up enough courage to start it.
Next to be done is the wiring. Main power is the afore mentioned 12v pack, this will drive everything except the boiler control unit, which will have its own power supply for safety, hopefully if the main power pack ever goes flat the boiler should be OK. All the lighting is 12v, so that not a problem, there will be at least 2 x 12v fans sucking air in to the hull, & the receiver will run off a home made BEC connected to the main batteries. A suitable plug & socket has been scrounged, which will transfer the power to the superstructure ala Bunkerbarges Ben Ain build ( thanks again Bunkerbarge).
Then the lead ballast has to be moulded & fitted. One useful point about having previously run the boats on electric power is that the all up weight & the centre of gravity are known, the dis advantage of going steam powered is 2 huge sla batteries have been removed, so they need replacing with lead ballast permanently fitted to the hull, making it heavy for transportation.The lead will be cast to the required shape using plugs made by pouring plaster of paris in to the bottom of the hull, a method i have used successfully on other builds.so a fully explanation & pics will follow soon ( i hope).
Cheers Glenn
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Topic: empire tug steam conversion (Read 12020 times)