Assuming ~20 stories aka 200 feet is reasonable at 100 feet per second acceleration aka just over 3 g's in 2 seconds the base of your rocket is just over the 20 story building and your doing 130 MPH. Even still that building is still going to be blocking a lot of sound as the fire is below that level.
7 seconds after launch your (5 after clearing the building) your doing 477 mph and have traveled 1/2 a mile. At 12 seconds your doing 820 mph and have traveled 2 kilometers up.
PS: Falcon Heavy is apparently ~160db vs 120db for thunder, which you can barely hear at 10km. So, it's going to be noticeable at 10km, but not that noticeable.
This is an incredible idea for subsidizing the Mars rocket program via rapid transit for executives, heads of state, etc.
Of course it would also have to be demonstrated to be at least as safe as air travel first before it would hit the mainstream in that market.
Even if my numbers are out Concorde was borderline viable and BFR should be more capable of bringing in money.
Plus you go into frigging space. Branson wants to sell just that, this gets you into space and down to China.
Another advantage I can think of over Concorde is that there should be more space and the trip is only ever 30-40 mins, so no cramping up in the seat.
Finally a Concorde ticket was about $12,000, BFR was mentioned to be $1-2k at the end of the video.
However, your point about cramped space made me realise that although the BFR isn’t going to be volume limited, that’s because it’s mass limited. Every 10kg of luggage will add about $250 to the price.
Fortunately we didn't stop our pursuit of progress due to such challenges. Now 3.5 billion or so passengers take extraordinarily safe, comfortable flights every year.
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.
At best one could maybe speed up pre-planned movements, as opposed to allowing a QRF to more rapidly react.
That sounds not too bad. Two 15 minute burns sounds in the realm of possibility.
Edit: changed some numbers and my conclusion.
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.
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.
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.
Plane crashes still happen too, but with significantly less frequency.
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.
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.
- 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.
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.
In some sense this is true, but keep in mind you're not actually creating more time -- time spent on business jets can be quite productive, in-person encounters are not always necessary, and it is often possible to use scheduling to get two powerful people in a room together when they happen to be near each other anyway.
Also not sure if the video goes into this, but rocket launches are LOUD, and so tend to be away from densely populated areas -- plan on another 20-30 minutes on each side to get to/from the pad.
(Maybe tunnels will help with this? Load yourself into a tunnel pod, which then gets robotically loaded on the rocket, so door-to-door transport? Man, the future's gonna be sweet!)
Using this as an example because I make this trip often: I can fly Cincinnati, OH to Charlotte, NC on a VIP airline for $500 round trip. I drive my car right up to the plane, and there is a rental car waiting for me at the plane exit on the other side. The entire plane is first class only. There is no baggage check, no TSA, no nothing. I can walk on to the plane 5 minutes before takeoff.
A domed, self-sufficient, city in Antarctica would also be a cheap way to test most (not all) of the tech needed for Martian self-sufficiency, along with the psychological impact of living in a desolate wasteland where rockets are the only way in or out, and it would be a good insurance policy against many possible global catastrophes.
Deserts, volcanic landscape like those of Hawaii and even a large enough basement would be just as good of a simulation without needing to worry about the environmental impact in Antarctica.
And plus we already have a "city" there.
``I'll believe in people settling Mars at about the same time I see people settling the Gobi Desert. The Gobi Desert is about a thousand times as hospitable as Mars and five hundred times cheaper and easier to reach. Nobody ever writes "Gobi Desert Opera" because, well, it's just kind of plonkingly obvious that there's no good reason to go there and live. It's ugly, it's inhospitable and there's no way to make it pay. Mars is just the same, really. We just romanticize it because it's so hard to reach.``
That said however settling the Gobi isn’t cool and as such it won’t drive innovation that could and would improve life on earth.
Sure, Mars is cool and I intend to by a ticket, but making Earth deserts productive sounds like a great improvement down here.
If that isn’t a problem for you then sure go a head.
Mars would require us to solves many more problems which can be then used to solve problems here on earth sometimes a bigger challenge is required to push for a breakthrough.
But if we go about geoegineering then I rather terraform mars which by all accounts is a dead planet than terraform the less livable places on earth as they are a host to their unique life forms.
> A domed, self-sufficient, city in Antarctica would also be a cheap way to test most (not all) of the tech needed for Martian self-sufficiency
GP is talking about testing the rockets in Antarctica.
This doesn’t mean it doesn’t matter, but my engineering skills are purely software — I really am asking if it would matter because I don’t know.
In other words, how to make human pancakes in 30 minutes.
But really, these are ballistic trajectories. Are we going to put everyone in G suits? And you're going to really restrict who can/will go on. They will likely go slower, so everyone doesn't have to go through endurance training.
Plus, being 5k-10k out from land, the total trip is definitely going to take much longer than 30 mins (yeah shorter than the airline flight), to get people on to the boat, onto the rocket, baggage loading, etc. It takes about 30 minutes between when they start loading people onto a plane and when they take off (and baggage is already on!).
Let's be real, if they get it working, it will be 2-3hrs trip. Which is still great, but not 30 minutes.
I assume you mean because minimum-energy ballistic trajectories come into the atmosphere very steeply, so the G-forces are much higher.
But by using flatter trajectories (closer to an orbit than a parabolic "hop"), you reduce the angle of entry considerably, at the expense of using more fuel.
The result is that for Earth-to-Earth rockets, essentially all trip distances require the same amount of fuel.
>It takes about 30 minutes between when they start loading people onto a plane and when they take off (and baggage is already on!).
I wonder if they can pack baggage into a lightweight "carriage" during the boat ride, the simply load that single carriage onto the rocket. Or even a few carriages.
It will incur a mass penalty ("box within a box"), which means fewer passengers. But if it speeds up total trip time it could improve competitiveness with long-distance plane trips.
Either that, or just force everyone to buy SpaceX-brand standardized luggage that's ultra mass-efficient and supports automated handling/loading. :)
If it makes sense for airlines, it stands to reason that it probably makes sense for rocket-based passenger travel too. Though I expect the containers will be even more heavily mass-optimized than those used on airplanes.
My apologies for not including the link:
He raises excellent points imo.
I think noise/safety are the real show stoppers. You can get the noise down by moving it further away from civilization, but I think the distance required would simply be too far. I also don't think a rocket will ever approximate the safety of a plane with current tech. If it was 10x more dangerous than a heavy aircraft (which is highly optimistic) would anyone go?
I think SpaceX can make it work, can make it affordable to some degree, but making it a practical form of travel is ... yeah, no.
I have no problem with them trying though. Their money.
His "debunking" of Goodenough's battery shows that he doesn't understand the difference in the way energy is stored in carbohydrates vs batteries.
If that's so then I find his videos intentionally misleading and remain skeptical.
Edit: added newline.