two of which resulted in fatalities.
Sigh. One of the crashes resulted in one fatality. The other two crashes, no fatalities. (And it is not yet known whether Autopilot was engaged at the time of those two incidents.)
Getting distracted with Autopilot engaged is like removing your seatbelt because you have airbags. You may be able to occasionally get away with it, but it's still an incredibly dumb thing to do. (And the former endangers other drivers, not just yourself.) The silver lining of these incidents is that maybe more drivers will start paying more attention while using AP, though it should have been up to Tesla to properly instill this sense of caution to begin with.
And side skirts/guards should really be mandated for trailers nationwide. (They're already mandated in California.) It may not physically prevent an underride at high speed, but it doesn't have to; the radar is much more likely to detect them and trigger collision-avoidance braking. It's only a small patch for a small part of the problem, but better than not patching it at all.
There are two reasons that I've seen.
Third reason: Wind. In the post-launch press conference, Elon mentioned that the wind was significant during landing. (And may reach up to 50mph tomorrow on the way back to port.) So the rocket had to tilt somewhat into the wind to avoid being blown sideways relative to the landing pad, and only went vertical at the last moment. It also explains why the droneship maintains a slight tilt in some of the post-landing footage; this is to cancel out the considerable force of the prevailing wind.
And after these five years, I'd expect the range of the car to have dropped 20% or so.
Um, no. I own a vintage 2008 Tesla Roadster, and its range has dropped only about 10% over nearly 8 years. The battery chemistry and durability used by Tesla has only increased since then, so I the Model 3 will do substantially better even than that. Over five years, it might drop 5%. Possibly 10% at the outside, but not anywhere close to 20%.
Now here's a huge issue I haven't seen anyone talking about that gets progressively worse as the track/tube length increases, subsidence and ground movement.
The subsidence / ground movement effect is dwarfed by the simple thermal expansion of the tube over the day/night cycle, which can grow/shrink up to hundreds of meters over the length of the tube. This effect can be compensated for by allowing the tube to slide smoothly across the pylons to achieve tensile equilibrium. (Perhaps with motorized assist to overcome friction.) The "slack" is taken up at the endpoint stations, through a telescoping system. Each pylon can allow for perhaps a meter of lateral flex to account for local ground shifting, and the pylons themselves can be easily repositioned if they start to get close to their tolerances in a local area.
By the way, how much material would such a full sized tube use up, and whats the current national production of said materials?
The complete Alpha-design hyperloop from LA to SF would use about 1 million tons of steel, or about 0.02% of the world's current annual steelmaking output. For scale, this is about 10x more steel than the Birds Nest stadium in Beijing, or about 100 Eiffel Towers' worth.
And how much gets bled off into space?
Much less than would be if there weren't so much CO2 in the atmosphere trapping the heat. As we inject more CO2 into the atmosphere, less heat escapes to space, and the equilibrium surface temperature rises quickly. This is why the human-caused rise to its current value of >400ppm is so alarming, and where the ultimate 350ppm "safe" limit calculation (to avoid catastrophic temperature increases) comes from.
A person needs at least 20kPa *from the mask to breathe*. Not 20kPa *ambient pressure*. Please learn to read.
The mask pressure must match the ambient pressure, or else the wearer's lungs will rupture (unless they're wearing an enclosed pressure suit). Please learn physics. Again, this is the reason for the 40,000ft flight ceiling for commercial aircraft; oxygen masks rapidly lose their effectiveness with an ambient pressure below 0.2atm, which is why pressure suits are required for pilots flying at higher altitudes. The absolute physical limit for unpressurized flight is known as the Armstrong Limit, which occurs at about 62,000 ft; even wearing an oxygen mask, your bodily fluids will start to boil above that altitude.
The "problematic loading on the capsules" is from the high speed aerodynamics, not the ambient pressure
Aerodynamic loading = pressure. If you have high loadings, you have high pressures. Period.
The high loadings are from high _variations_ in pressure. The average pressure around the capsule is still equal to the ambient pressure. Leaks in the passenger compartment are almost certainly side-facing, so the capsule will equalize to the pressure of the air on the sides of the capsule (which will be close to ambient or likely below, due to the Bernoulli principle), not the higher pressure in front. And note that the variations in pressure don't have to be very high to cause serious buffeting. The Hyperloop capsule masses 15000kg, with a frontal cross-section of about 2 m^2. Applying an extra 1atm to the front of the capsule will decelerate it faster than 1g. If the air beneath the capsule transiently becomes about 0.03atm higher density than the air above (due to turbulence or ground effect), it will lift the entire capsule off the track. This is the worrisome high-speed aerodynamics I was talking about.
Beware of Programmers who carry screwdrivers. -- Leonard Brandwein