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When discussing a vacuum container at sea level the pressure on the container will be one atmosphere which is 101kPa or 15psi and not equivalent to 10 meters of water.

The pressure differential between a container of perfect vacuum and ambient atmosphere at sea level is about 14.7 psi. The pressure differential between a container of air at one atmosphere and ambient seawater at 10m depth is about 14.7 psi. Each 10m of seawater depth increases ambient pressure by approximately one atmosphere. At 100m, pressure is 10 atmospheres higher than the surface. Freshwater is less dense than seawater, so pressure increases a bit more slowly.

Any SCUBA diver knows this.

Here's a calculator if you'd like to play with it.

For starter people like Leonardo da Vinci (1452 to 1519) knew about flight structures well before the first powered flight. From then on aircraft developed quickly...

I'm not sure I see the point you're trying to make here. As many people are keen to point out the notions of vacuum tubes, magnetic levitation, air bearings and indeed pretty much every engineering concept used in the hyperloop proposal are not new either.

When discussing a vacuum container at sea level the pressure on the container will be one atmosphere which is 101kPa or 15psi and not equivalent to 10 meters of water.

Are you sure about that? I'll repeat my original assertion in case you misread it: "The pressure differential between the atmosphere and an evacuated tube is roughly equivalent to a tube at atmospheric pressure submerged in 10 metres of water"

...what has been proposed is a vacuum tube that is well over 100km long...

The original proposal was for a route that ran from LA to SF, so roughly 560 km one way, or a 1120 km circuit. You don't find it funny, as an engineer, that you clearly haven't read the proposals, or follow on documentation, but you're happily telling us what you think they said?

...supposed to be traveling at around 1100kph (700mph) and all it takes is a minor fault or rupture and you have human salsa.

Yup, and when a car crashes at 120 km/h, when a train derails at 200+ km/h, when a plane depressurises or crashes people tend to die too. It's not possible to be so risk averse as to avoid all possibility of harm, because if you were to try you'd starve to death from fear of choking. I'd say much of the fear surround this idea is fear of the unknown - a natural human reaction, even if a tad 'over-sensitive'.

You can even look at the Concord and I will leave it up to you to find out why we don't have supersonic passenger jets anymore

Mostly it was because it couldn't fly supersonic for a great deal of its routes, due to the sonic boom. It was also a bit of a gas guzzler. So, it didn't save as much time as was originally envisaged, and it was very expensive. In other words it stopped flying due to economics, rather than any technical reasons. Again, what point are you trying to make?

As an Engineer, I am all for science and advancement but I also like to see the evidence (you know the Scientific Method) before I agree or disagree

You'll excuse me for saying so, but your posts don't seem to suggest this. It rather seems, by posting the links you have, that you have very much decided already.

As for annoyingly smug, I don't find Thunderfoot that way since he always provides evidence and that is what I care about.

The most visceral demonstration I think I saw him give was him putting a ball bearing in an evacuated glass tube, then having snapped the end off, and watched the ball bearing shoot down the tube and smash through the end he suggested that this showed that any hole in the hyperloop tunnel would 'wreck' the transit pod and or tunnel and kill all the passengers...

So let's examine this demonstration and the claims:

Did snapping the end off the evacuated glass tube, causing air to rush in, destroy the rest of the glass tube? No, it did not

Was the cross sectional area of the glass tube roughly twice that of the ball bearing? No, it was not

Is a small ball bearing in any way equivalent to a 15+ tonne vehicle when considering the effects of a certain mass of air hitting it? No, not really

Does a 3 foot length of evacuated tube share the same characteristics when repressurising as a 300 foot length of tube? A 3000 foot length? Not exactly. Once you get beyond about 33 feet (essentially the pressure difference between a vacuum and 1 atmosphere) things change

So tell me, what 'evidence' is he providing exactly?

The short of it: it's basically a pipeline, so you start with base pipeline costs for the given diameter.

And there is your mistake. Everything you wrote after that is invalid.

For starters the hyper loop is a vacuum chamber not a pipeline. Pipes keep fluids under pressure in. Vacuum chambers keep air out. This means a number of differences starting with just the differences between how the tubes are sealed. Vacuum chambers require vacuum welds or else you end up with virtual leaks. Pipelines welds requirements are simpler.

Pipelines have much lower pumping requirements. Some pipelines don't even have pumps because they can use gravity. By contrast, a vacuum chamber vacuum pumps operating 24/7 to maintain vacuum.

I suggest you learn what a vacuum system is.

HUGE amount of force trying to crush the tube. 14 lbs/ square inch.

The Transbay Tube has a maximum depth in water of 41m, and according to this calculator experiences 74.4696 psi at that depth.

The tube liner by itself would probably have no trouble handling the pressure. It will almost certainly be surrounded by steel-reinforced concrete or at the very least pipeline steel because building such things is well understood. However it's built, it'll be ridiculously over-built if an M-80 or a rifle is the biggest threat. A real terrorist IED is always a threat of course, but no more so than for traditional rail.

That depends on 5 main factors:
air density (depends on altitude)
aerodynamic shape of the object
Frontal surface of the object
Mass of the object
The gravitational acceleration on Mars (approx 4 m/s^2)

If I assume the air pressure of 1% of earth means that the density is also 1% then:
p=0.1225 kg/m3.
If I assume a C of 1 (approximately a man facing the planet, see here for more common C's), an A of 1m^2 and a m of 100kg

Plug all that in a calculator like this one.

Then I get a terminal velocity of 82 m/s (or approx 300 km/u), if you drop down flat.
For earth that is approximately 145 km/h. For 300 you have to go face down (lower C and lower A).

What kind of brick?

• A common red brick has a mass of 1922 Kg/m^3 (ref)
• A standard brick has dimensions of 3 5/8" x 2 ¼" x 8" (ref)
• The smallest side (and therefore ideal side for max terminal velocity calculations) is 3 5/8 x 2 1/4, and therefore 8.15625 square inches
• The mass of the brick would be 2.05510989 Kg (Google calculator ref
• The coefficient of drag would be 2.1, according to this calculator site (which, incidentally, gives a nonsensical result of 3mph - which is why I did the math myself below)
• The density of air at 35 celsius is 1.146 kg/m^3(ref), and 95 F seems pretty optimistic for the salt flats this time of year.

So, Let's do the math with Google so I don't have to convert units, using the formula here. Since Google complains about square roots with more than a number inside, we'll find the answer in mph^2 first, then take the square root of that. Here's the first calculation, which gives 15 932.3342 mph^2. Take the square root, and you get 126.2 mph. So, you're not going to do better with a common red brick. Maybe something with a smoother surface, higher density, or a smaller surface area would be better... :)

I'll bet that's closer than you expected.. ;)

Obviously the energy is built up over the period between pulses. And since the repetition rate is only 1 shot per HOUR, the average power output is only 0.1 W!

That wouldn't even put a dent in my electricity bill.

Yes I know, I know...

To be fair, a 5mW laser point would need to be focused to a diameter of ~10 microns to reach the sun's surface intensity of ~6kW/cm^2.
And a cheap laser pointer can't be focused to that size.

But of course you're right. They're just going for the unwashed public wow factor.

When I reported a (fairly serious) issue with Safari on my new calculation project website, it was fixed within a couple of weeks. I don't really know if it had anything to do with my report, but I like to dream...

Or you could just calculate it online in any of a million places, and have somebody else do the coding...