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Comment by gldalmaso | Hacker News Reader

I have yet to see any mention of how the passenger experience is going to be. I assume it is much worse than some ear pain on take off and landing. Can the average person handle this trip comfortably? Or do they have to pass some astronaut-like conditioning test?

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There was some analysis on the SpaceX subreddit saying the G loads would peak out at 4 Gs. So a bit worse than those carnival rides where you stick to the pads on the periphery of a spinning room, which IIRC are only 3 Gs. With a well padded reclining seat it should only be mildly unpleasant for healthy adults but I worry that there are potential customers who won't be able to deal with it.

> Or do they have to pass some astronaut-like conditioning test?

I wonder about military applications. One would imagine that special forces groups would meet requirements. Being able to move SEALs around the world in a matter of minutes would be a boon for force projection.

Rocket launches take a certain amount of planning and favorable weather. Plus, they are impossible to hide. All in all, not desirable.

Ah, I forget that rockets are no where close to planes...

At best one could maybe speed up pre-planned movements, as opposed to allowing a QRF to more rapidly react.

Some of the things Burt Rutan has said over the years imply that this niche is already filled.

Assuming 1) a trip is about 10,000 miles in distance, 2) acceleration is constant and speeding up for 15 minutes and slowing down for 15 minutes, they are looking at (very roughly) 0.4g of additional acceleration i.e. you would feel 1.4 times as heavy as you do standing still on takeoff and landing. As you angled horizontally, the effect of earth's gravity would be counteracted by your centripetal acceleration so that you would feel approximately 0.4g at the midpoint of the flight. So 1.4g at takeoff and landing, 0.4g at the midpoint (again assuming constant acceleration due to thrust)

That sounds not too bad. Two 15 minute burns sounds in the realm of possibility.

Edit: changed some numbers and my conclusion.

Forget about comfort. Rocket engines are dangerous and unreliable compared to planes and any other mode of transportation. People aren't going to tolerate the risk.

>Rocket engines are dangerous and unreliable compared to planes

To be fair, that's the problem they are trying to fix. This is like telling Microsoft that personal-computers will never work because they are big, expensive, difficult to use, and crash all the time.

> This is like telling Microsoft that personal-computers will never work because they are big, expensive, difficult to use, and crash all the time.

That's not a fair comparison. The energy difference between a rocket engine and an airplane combustion engine is huge. Rockets are all about raw energy output and are essentially a bomb. The fuel is volatile, and rockets use a lot more fuel than planes. If a failure happens with rockets, the whole thing usually ends up blowing up catastrophically.

Rockets are inherently more dangerous. But hey, more power to them. I would love it if we can make rocket flight safe enough for everyday use by everyone.

To be fair, only half of those statements have changed. Computers still crash all the time, just less frequently than they used to.

>Computers still crash all the time

My personal XP is 20 years my computer crashed 1-5 times a day, now days my computer crashes maybe once every 4-6 months. That is considerable.

But there's a magnitude difference there from "the early days".

Plane crashes still happen too, but with significantly less frequency.

In general if your PC crashes you don’t explode though.

But now we have computers running our planes, running our cars, running our pacemakers.

Your PC might not kill you, but the software running the drive-by-wire system in your car will.

Still, my point wasn't to get into a discussion about the differences between software and rockets, but more to point out that their goal is to change those things about rockets. To make them reliable, safe and cheap.

You can think they won't be able to pull it off, but saying that it will never work because it doesn't currently work that way seems a bit silly.

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