Referring to this quote from John E
Bob was saying though he also built (up to now) 3 steam turbines and he is on with his 4th build of a turbine at the moment.
Bob feels that the most successful turbine that he has built to date was a single rota of a 4 inch diameter across the blade tips; he did not inform me of how many blades the most successful one had; but, are you waiting for it......
it ran on 150 PSI super heated steam; at 3200 rpm. The boiler itself was a figure of 8 configuration with twin burners - one down each '0' opening of the 8 -I think Bob said that the boiler was roughly 12 inches long but he did not tell me how many loops or figure 8's were in this length.
This is a perfect example of why I made a prototype. You need information from test runs and trials. As you can see, Bob is onto his fourth turbine, most probably, each one is better than the previous attempt.
Us small scale machinists are working, basically, in the dark. We don't have multi billion pound R&D departments, so trial and error and a basic understanding of the technology has to be the way we go. Just for a simple thing like a nozzle jet can take dozens of attempts to get one that works efficiently at the size we make. Each one taking say a couple of hours.
I know for a fact that the larger rotor turbine that I originally made is a lot more efficient and produces more power than the one I have just made, but I was given a size and quantity constraint, so my testbed was built to fit that parameter. Just to see if it was feasible to make a matched pair to power this boat. I made the engine for my love of engineering. To get to a stage where the original idea can be put into production might take a few more trial and error engines, in that situation it then doesn't become feasible for Cap to pay, say a lowly basic £10 per hour (and most probably a lot more) making costs to produce further R&D engines. He will soon be up into the many thousands of pounds.
OK, say I got an engine that worked efficiently on the second trial. It has been shown that powering it is going into another experimental area. People have been doing these boilers, as experimental exercises for most of their lives, striving to get a 'perfect' one. Again, mainly due to trial and error, suck it and see exercises. Copper tubing in these 'experimental' flash boilers, because of the pressures and temperatures involved, is no use, so you really have to be looking at stainless steel and other exotic materials just to keep the thing from failing. You are now looking again at high development costs, because these back yard machinists and builders cannot be expected to give their time and materials for free. We do have normal lives to lead.
If someone came to you and said, your are a model boat builder, here is a picture of a totally unique model I want building, can you make it such and such long, you can do all the R&D. How long would it take you to make. How long is the proverbial bit of string?
What I am trying to get at here, I have done the first basic prototype for free, and I really enjoyed doing it and is now a proud part of my experimental engine collection. But even at this early stage, major problems are starting to rear their ugly heads. To carry on with this trial and error exercise that was originally inspired by Cap wanting to have a turbine powered model, would in my opinion be a VERY expensive and long term project. If you can get someone to work for nothing for a few hundred or maybe thousands of hours, then I will gladly share what little information I have. Maybe Nick from Monahan has the time to help.
I am not admitting defeat, a couple of more protos and I am sure that the engine side could be sorted. But the costs would be very prohibitive. Now if you could find a good, guaranteed working sets of plans (not the ones you see in books that say, this is how I did it and this is how to make it type, dating back to the early 20th century, they will most probably still be experimental), it would then be feasible, as all the R&D has been done and they could be knocked up fairly quickly and cheaply.
Cut your losses now, it has cost you nothing to get this far. To go any further with this project is going to hit you hard in the wallet area, and at this moment in time, the feasibility is a non runner. Revert back to the secondary option of going down a proven route, electric motors, and get a turbine sound board.
John
