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While I agree with you that there's a desire for this I'm not yet convinced there's a market for it. As you say, this needs to be proven to be at least as safe
by cletus 8y ago
While I agree with you that there's a desire for this I'm not yet convinced there's a market for it.
As you say, this needs to be proven to be at least as safe as air travel.
Beyond that, for certain wealthy individuals, government dignitaries and the like commercial flight represents an unacceptable risk and cost in time eg Apple's board requires Tim Cook to fly private now.
Next, if the launch and landing pads are indeed offshore and otherwise remotely, this adds travel time at either end.
Also, rockets are subject to weather much more than planes are. If your landing pad is offshore then those weather effects are more pronounced as you have to deal with sea conditions too.
Lastly, current SpaceX landing is a "dead stop" approach (vertical velocity is designed to hit 0 when altitude is 0), which seems like it may not have the safety margins for mass transit. Future designs may of course improve on this.
So much as we'd like this, I'm not yet sure how we get there. Planes have to log many thousands of hours to be certified for passenger flight. Will we have enough launches to certify rockets this way? Even reusable rockets are, in comparison to planes, expendable because they're combusting huge amounts of fuel. Like I don't see you reusing the same rocket every day for 30 years like you can with a plane.
- mongol 8y agoI don't understand your point about dead stop approach. What would be the alternative?
- cletus 8y agoIt's an issue of safety margins. Just consider the airplane. - A two-engine plane can operate on just one engine - In the event of losing power or losing both engines, a plane has a certain glide capability - Runways are built allowing a certain amount of overshooting - A bad approach allows you to circle back around and try again - Planes can land and takeoff with significant winds and precipitation (including cross winds) - A plane can actually land in a body of water (as happened on the Hudson). Now compare the safety margins for a dead stop rocket reentering from space at Mach 30.
- skykooler 8y agoTo address your first point - the rocket has 3 sea-level engines on the spaceship stage, each of which has enough thrust to land the ship on its own if the other two fail. (This is partly a byproduct of it being much lighter during landing than takeoff as most fuel has already been burned.)
- alonmower 8y agoI think the issue with the current hoverslam solution is that the timing of the rocket relight is critical to the rocket hoverslamming (and not just regular slamming). I don't have the answer to this but imagine that if an engine fails to relight at the correct time there's a much smaller (or maybe non-existent?) margin of error. A plane on the other hand has two engines and can also generally just glide to the ground in the event that neither of them are working.