Recent content by Ken Fabian

It the fundamental nature of the grandly optimist goals and the appallingly bad economics needed for achieving them that leaves me deeply doubtful. The tech - STEM - is amenable (hypothetically) to solutions.

My thoughts and reasoning on this go a long way back. Just the expression of them is subject to change.

A correction to the comment. Thinking I'd have no time for on-line. I'm loaded with steroids right now for medical reasons, they are kicking in now and it could become a case of can't shut me up! I do really enjoy (some of) the exchanges and the thinking things through part is a big part for me.

@DaveC426913 - a belated follow up to my previous post. "The Moon Goddess and the Son" - Donald Kingsbury, impressed with the launch tech, which I borrowed from. In reality I can only consider it all fantasy and a recreational activity; when people take it seriously, as if realistic...

But this seems to occur because there is some looseness to take up before the drive chain fully engages. Start with none of that looseness - with the drive chain pre-loaded - it should move forward. And in a real situation - unless you are one legged - there would be forward force from the...

I think @Lnewqban has it right; the water at the base gets replaced rapidly and mixed with adjacent cooler water whilst the warmer water that rises tends to accumulate at the top, especially if the heating is slow rather than fast enough to cause vigorous overturning and mixing through the whole...

@Baluncore - If I am wrong in this it is wrong with conviction. I don't think I am wrong in this. There is a rebound of water hammer hitting a compressible body of air, be it air in the air chamber in the time before the delivery valve shuts or bubbles before a stuck delivery valve - which...

Diagram, with terminology - which other diagrams may name differently. @Baluncore - I disagree - the amount may be small but there will be some backflow, a physical volume of water returning to the drive pipe before the delivery valve closes. Water compression delivers no additional physical...

It is interesting thinking it through - not so much reading of references in this case; it is good for my brain, whilst noting that what I think sometimes leads to what is correct but sometimes not. In this case it is turning out more complex than my initial thinking, or even my first few...

Nothing like being wrong with confidence.

Okay, I stand corrected. Had been thinking about it and realised that, yes, there needs to be a moment of negative pressure for the waste valve to re-open. The extent to which that is rebound from water compression rather than a product of the pipe expanding and recoiling I am still thinking...

@Baluncore - My experience was with a variant type, so details vary. My non-return valve had a spring and had other differences but principles are the same. Why a straight pipe appears to deliver a better pressure pulse seems a different question to how the 'waste valve' re-opens. On mine the...

That is what the main 'slam valve' does (Not sure of correct terminology). At the start of each cycle water flows down the main water feed pipe and spills out freely, back to the river - effectively a pipe open at both ends - until it is flowing fast enough to slam the valve closed. Most of the...

Whilst every material outside of a black hole is compressible I do think very low compressibility of water is a crucial factor for ram pumps to work. Loose terminology to say 'lack' of compressibility rather than 'very low' perhaps. I think a compression wave passing up to the reservoir is NOT...

Fusion still appears to need an abundance of reaction mass - that might colloquially get called 'fuel' . The fusion engines part seems likely to have a lot of fixed mass, which will require more reaction mass, undercutting some of the gains from high exhaust velocity. There are trade-offs. If...