I'm crossing fingers for Elon Musk and SpaceX rockets.

Sonic booms go parallel to your path, so a vertically moving rocket has a sonic boom that goes parallel to the ground and doesn't bother anyone.

However the big issue with rockets (other than technology which SpaceX thinks that it can handle) is that about 1/3 of people get sick in freefall. (Estimate that I read from the operators of the vomit comet.)

The other problem is that the BFR would carry 10 kt of fuel. Even a very small chance of that much fuel exploding anywhere near a major city is too much risk, so you'd have to put them well away from population centers. So you can tack on a couple hours to the spaceport on each end.

SpaceX's vision was a 30 min ride on a high speed catamaran. Depending on details that probably puts the landing pad something like 15-20 miles out in the ocean.

Do you think that that is unreasonable?

Well, something to consider is that Little Boy (the hiroshima bomb) had a yield of roughly 15kt. Obviously a nuke has different characteristics from a fuel-air explosion, most of which I haven't considered and would not qualified to comment on anyway, but the comparison doesn't make me very comfortable with 15 miles. It probably wouldn't be within the blast radius (depending on how the burning fuel propagated), at least, but the the amount of radiant heat generated would be nothing to sneeze at. I could certainly be overestimating the issue - I'm guessing the rapidity of a nuclear explosion vs. a fuel air explosion affects its pound for pound destructiveness significantly.

Sibling comment has a good point that hyperloop could make spaceports at safe distances more accessible.

Hiroshima was total destruction within 1 mile, the farthest away that glass broke was 12 miles, no damage past that.

So 15 miles is definitely out of the blast radius. What about the fireball?

Google told me the following. 15 miles is roughly 24 km. The mass of air is 1.2 kg per cubic meter. The volume of a sphere is 4/3 pi r^3. The energy of a kt is about 4.184e9 joules. It takes about 1 joule to increase the temperature of air by 1 C. When I put all of that together I calculate that a 15kt explosion has enough energy to raise the temperature of a 15 mile ball of air by about 0.9 C.

Please double check my figures and calculation, but I think that your average city can survive that. :-)

Ha! Thanks for running through the numbers, very interesting. The air in that 15 mile ball is almost transparent to infrared, though, so I'd probably assume that the surface area of the sphere would receive the lion's share, rather than the volume within it. So the energy delivered should fall off roughly with the square of the radius rather than the cube. Might be enough to give a sunburn, if nothing else.

Edit: On my phone I'm getting ~5.8 joules per square meter. Google seems to be mangling the units, though, so I can't be sure it's not dropping or adding in a factor of 1,000, though.

Edit 2: assuming that figure is correct, unless it's released in <1/200 of a second, it's not competitive with the sun at the equator (>1,000 Watts/Joules per m^2 per second)

I think that there are some decimal places missing. But that said, I'd expect a chemical explosion to deliver itself mostly as a shockwave and a ball of hot gas, with relatively little delivered by light. Because the part exploding is surrounded by smoke and chemicals that absorb light.

Yeah, I was going for worst case assumptions, where all of the energy turned into infrared, which is definitely not going to be the case.

Here's the math, if you want to double check: (10 x 4.184 x (10^9 joules))/(4 x pi x (24000 meters)^2)

Atmosphere is only transparent to infrared in 7-13 mkm window. Yet I expect the fireball to producing heat at above 500 C that gives peak of radiation below 4 mkm.

Thanks, good to know. I was going for worst case calculations, assuming complete transparency. Even that doesn't seem bad.

Lenghty travel to spaceport would tie in nicely with the hyperloop.

Good point, that might make it more feasible. I hope we see some successful deployments.

This is lower, however, when you're strapped into your seat. In the vomit comet, you're free to move about, which drastically increases the likelihood of nausea.

The F9 makes a pretty disgusting triple boom on landing so I can't see the bfr being better in that respect.

Per SpaceX's plans, the landing would be some miles away from people.

A supersonic jet makes a sonic boom on the ground over its whole trajectory. That's what makes it undesirable for overland travel.

What? Surely you mean perpendicular to the path? Or does path mean something different from trajectory..?

I do mean perpendicular, sorry.

I really want it to happen, but I'll believe it when I see it.

I don’t think Concorde has enough range to be viable for Pacific routes. Maybe a redesigned version with greater range would work well though.

Mid air refueling works well for the air force.

I've heard it's cheaper (whether this is in terms of risk or dollars I don't know) to send up a dedicated tanker to top of a bunch of large planes that took off with little fuel than it is to make a bunch of large planes take off fully loaded with cargo and fuel.

The problem is that's a whole additional, expensive skill your pilots need.

Fuel from a tanker is an order of magnitude more expensive. It’s worthwhile for the military since they sometimes have a hard time stopping for fuel in the middle of a mission, and like using planes that prioritize the ability to kill people over the ability to go far, but I don’t think it would make much sense for airliners.

they also don't have to be profitable...

Air-to-air refuelling would be way, way, way too dangerous for commercial aviation to even consider.

I disagree, the bigger is the plane, the easier is the refueling

Part of that was due to ETOPS regulations which required twin engine planes to always be within a certain range of a ground airport for emergency landings.

A modern Concorde would almost certainly have an ETOPS rating which would allow for trans-Pacific routes, which is where the true time and fuel efficiency is to be found in supersonic flight.

Uh, Concorde was a quadjet? ETOPS didn't apply (and ETOPS didn't exist when Concorde entered operation).

Whoops, you're right, it was a quadjet. My memory screwed up because both engines on each side are so right next to each other, in my memory they fused into a single engine on each side.

Correct, Concorde had a range of 3900nmi (~7200km, ~4500mi).

LA-Tokyo is ~4700nmi (~8200km), and polar route flights are generally used by planes with a range around or above 7000nmi (~13000km) like the Dreamliner or the A350 XWB

It could stop in Hawaii.

Anchorage, Alaska was a more common stopover between the U.S. West Coast and Japan, Korea, etc. in the days before airliners could easily cross the Pacific in one hop.

ANC is still a major refueling and sorting stop for air cargo -- most all air cargo between China and the mainland U.S. passes through Anchorage. The Anchorage FedEx hub is only passed by Hong Kong and Memphis in terms of volume, and the UPS hub is also one of the largest for that company.

That's counterintuitive when you look at a flat map, but not on a globe.

Here's a flat projection of some great circle routes:

http://www.gcmap.com/mapui?P=SFO-NRT-SIN,SFO-HKG-SIN

Note that the shortest path goes a lot closer to Alaska than it does Hawaii.

Reminds me of something the boss of the company operating a former soviet cargo plane demonstrated. They often figured out how to get the plane somewhere by taking a piece of string cut to fit the flight range of the plane, and placing it on top of a globs to look for suitable airports.

Depends on the destination. Try Sydney, for example.

On most (all?) the round-the-world charters that Concorde did, it had two stopovers on every transpacific leg, one in Honolulu and the other variously in Papeete, Guam, or Fiji (and likely elsewhere, I've not looked exhaustively).

That said, the furtherest north any of those charters landed in the far east was Hong Kong.

You'd need a lot more range. The Concorde had a range of about 4500 miles. Even SFO-NRT (Tokyo) is over 5000 miles. And if you have to make a fuel stop--probably in Anchorage--you're really starting to cut into the time advantage.

Seattle is not right by the sea. It's separated from the Pacific Ocean.