landyacht said..Emeboy said..Now now kids.... Play nice
I think Macro likes to throw out the random ideas a little bit like science fiction or the movies making up a seemingly preposterous idea... Think 'Get Smart' way back in the day.... A shoe phone?? Preposterous!! Nowdays (nowadays?), we could put a phone in a shoe but prefer to carry them around in our pockets (actually Star Trek already had cellphones didn't they... Beam me up Scotty). A weird idea might just jog someone's thoughts to develop something better... or new.... maybe.... Trouble is, there are a million random preposterous thoughts to every feasible development.
Now for a spiral laid tunnel....
1. The size of the segment pieces required to create a single spiral helix would be way too big and heavy to handle. The Westgate Tunnel in Melbourne is 15m in diameter and each segment ring of 2.4m length requires 10 individual pieces. These pieces are approx. 13-15 ton each.
2. If you are considering a spiral laid tunnel in the similar fashion to a spiral wound pipe, the helix length required for even a small diameter (spiral) tunnel would be quite long, resulting in a significant portion of the freshly dug tunnel to remain unsupported while the helix was being constructed..... if you are going to make the helix a tight pitch and have multiple helixis (helixies, helixi???) which would allow smaller segment pieces..... then why not just make rings?
3. Even with concentric rings, the moulds for these segments are very precisely machined. If you now want to create a spiral helix and break that into manageable segments, the mould complexity would be significantly greater and therefore much more difficult and expensive to manufacture.
For a spiral welded fuel tank (presumably under significant pressure)
1. Hoop Stress..... (you might be better off wondering why they do not extrude the cylinders in one piece..... No welds seams at all)
Sorry Macro, these ones might just end up being filed under R....
This announcement was bought to you by the letters P for Preposterous and H for Helix.....
correct me If Ive got this wrong, but surely the sheets they are using are at some point in a huge roll that is rolled out and cut to size so that it can be welded back together . therefor deliver in a roll and feed into the robotic welder as a spiral then cut the end to finish that cut end is now ready to make next spiral. I would bet that the technology is already around and in common use but on a smaller scale, or even on a much bigger scale , like oil refinery tanks. just like when making a modern high pressure steel water pipe. EG the goldfields water pipe which they still make in steel because plastic isn't they strong enough. to me spiral make so much sense.
good thinking Landyacht.Now imagine what we could do with this technology implemented into small diameter tunneling.We need billions of km of tunel for infrastructure across the country and under cities. Any sort of cabling, piping , surage .But so far nobody invented machines that could continuously lay 1 meter diameter tunel encased in the concrete or plastic. Suppose that we want to make this High Voltage Direct Current power line to happen here in Australia.
From Perth to the Brisbane , by Adelaide, Melbourne and Sydney on the way. At first traditional power posts/ mast made of steels comes to mind. We have plenty of iron ore , we could make even steel of those one day.But once you start negotiation, land rights, view distortion, ecological damage etc the cost of research , litigation will dwarf actual build costs labour + materials.Go underground 50 meters or so, thatn paralel to the surface few km long, and all those problems are avoided.We need machined the could drill , remove material and make casting onsite at few km spans at least. Automatic , with minimal human intervention, without the need to go underground into those small tunel. I don't even mind to be transported by on of those underground pipes 1 meter diameter across the globe with 2 - 5 Mach speeds. Unlike elons Hyper loop 1 diameter pipe is so much easier to make and end effect is the same.
I could imagine such machine already. Long like erth worm ,chewing the sand and rocks in the front, piping matters back, then another pipes provide constant feed of reinforcing steel and concrete or plastic of molding , casting. Due to small diameter crushing this material at front is much easier and doesn't required tunel gigantic crowler. Even water jet laser could do the job efficiently on this small scale.
