[thesash]

There are three things that would factor into my decision about whether to strap myself to a rocket rather than fly in a plane: time, cost, and safety.

Musk & SpaceX are talking a lot about time and cost, but safety is obviously a lot more important. Based on data I found on the internet (so it must be true!) the loss rate for rockets is 20k - 165k higher than the fatal crash rate for airplanes over the past 20 years.

Loss rate for manned rocket launches [1]: 0.79%

Loss rate for unmanned rocket launches [1]: 6.68%

Rate of airplane crashes with at least one fatality [2]: < 0.00004%

Even if SpaceX is able to make manned space flight 10x safer, I'm not sure I'd trade 19 of the 20 hours I spent traveling from LA to South Africa this summer for a 1/1,300 chance of blowing up during launch.

[1] https://space.stackexchange.com/a/12229

[2] http://www.planecrashinfo.com/cause.htm

[Robotbeat]

Loss rate for space launches is largely due to the fact that the systems are essentially munitions (i.e. expendable, single-use) and flight rates are very low.

Rocket failures for crewed rocket launches are extremely rare, occurring once every couple decades. It's hard to improve on that because low flight rates make data very hard to come by. Airplanes fail much more often in absolute terms, giving you a lot more data to work with (especially when combined with near-misses) allowing you bring the relative failure rate very low.

Increase flight rates by 5 orders of magnitude, and you may be able to increase reliability by, say, 4 orders of magnitude.

[simplicio]

The problem is that to increase flight rates by 5 orders of magnitude, you need demand to increase by that much. And people are unlikely to demand rocket flights until after they're as safe as plane flights.

Early passenger planes were pretty dangerous to, but they got around the above problem by a) being much faster than trains, making the risk worth it, b) having clear military applications, the military being less worried about losing the occasional aircrew.

I don't really see how SpaceX gets around that chicken and egg problem.

[Robotbeat]

They're going to get around it because this is a secondary market for BFR. Primary market is launching satellites (especially their constellation).

Remember, this point-to-point idea was basically an after-thought. It's decades away, but the rocket will be launching within the next 3-5 years. So they'll have decades to get it right, and the manufacturing line and much of the infrastructure will be paid for.

But you're right about demand. The biggest economic problem is that it's too big. Each BFR needs 1000 passengers. To be economic, it needs to fly multiple times per day, so each BFR needs to fly like a million people every year. Look around to how many people fly long-haul, and you saturate the existing market VERY quickly.

BUT the world is getting richer. Soon (50-80 years?), there will be 5-10 billion middle class folk in the world, an order of magnitude more than now. And if the time for travel can be cut short like this, then you should have some demand induction taking place. So maybe it'd start making economic sense.

There is a fundamental advantage for BFR versus existing aircraft: SpaceX is able to make Falcon 9s and probably BFRs for about the same cost (a little less, actually) per unit dry mass as a 737 or 777 or A380. But a BFR can do trips that'd last 15 hours in a 777 or A380 in less than 1 hour. That means you can do 10 times as many trips, cutting your amortization time and crew hours by an order of magnitude. But that depends on having enough demand, which is pretty questionable except in the long-term.

[simplicio]

Total orbital rocket flights/yr are usually considerably less than 100 though, so I'm sceptical they'll ever approach airplane reliability with so few flights.

Honestly, that's kind of why the BFR idea kind of worries me. It feels like SpaceX analysed the need for orbital space-flights, and realized there was unlikely to ever be the kind demand that would provide the economies of scale needed to do what they want. On the otherhand, there's undeniably a large demand for terrestrial travel, so they came up with a way to use rockets for that purpose. It feels like something to show investors, rather than a workable plan.

But hopefully I'm wrong. Economics aside, its certainly cool, and it would be nice to have an application for terrestrial missiles other than nuclear annihilation.

[Robotbeat]

"Total orbital rocket flights/yr are usually considerably less than 100 though, so I'm sceptical they'll ever approach airplane reliability with so few flights."

"with so few flights" is the operative phrase there.

Current launch market is about 60-100/year.

This is why SpaceX invented its constellation: not only does it allow them to make a lot more money than just doing a few dozen launches per year, but it allows them to generate their own demand for launches to justify these crazy Mars rockets. The constellation is for about 12,000 satellites replaced every 4 years or so. Initially 500kg, but Mueller (rocket guy) recently hinted they could get much larger (so let's say 50-100 tons). Therefore, they'll be able to self-generate between 30 and 3000 annual BFR launches on their own. This point to point thing is another add-on market, could be even larger from a launch volume perspective (but, interestingly, smaller from a addressable-market revenue perspective than the constellation). With 3000 flights per year and margin to spare (and the benefit of post-inspection of the rocket in case of a near-miss), you should be about 100-1000x as reliable as today's crewed rockets just to start. Now add point-to-point, and you can do 50,000 BFR flights per year...

[1053r]

You answered your own question: military applications.

The US Armed Forces would pay a LOT of money to move 100+ tons of personnel and materiel anywhere on earth with a flat landing spot in under 60 minutes.

You could have tanks on the ground that were fully operational in under 3 hours (probably half that if they left the BFR packed and fueled for takeoff at all times), or a disaster recovery base set up within 24 hours of the winds dying down (to pick a more topical example.)

[simplicio]

Maybe, though the military has studied similar ideas before and nothing has ever come from it, so I'm sceptical they're going to throw the kind of funding at it that would be required here. As a general concern, actual travel time doesn't usually seem to be the main determinant of how fast military forces can be deployed.

But who knows. The idea of a big capsule coming down in a war zone and a bunch of tanks and marines rolling out certainly seems pretty cool, and I'm sure Musk and his lobbyists will at least try and convince the DoD that its something worth throwing a lot of $$ at.

[thinkcontext]

Its not "anywhere on earth with a flat landing spot" if you want to be able to retrieve the thing. It either needs to go somewhere with the very specialized launch infrastructure and personnel it needs or the ability to transport (how to you transport a 48m x 12m cylinder?) it to somewhere that does.

[thinkcontext]

They can fly cargo. FedEx would definitely be able to market such a service.

[simplicio]

Yea, but the main advantage of the system over air-travel is that it's fast. For most types of cargo, cost rather then speed is the main issue, especially if the difference is just on the scale of a few hours.

[thinkcontext]

When shipping internationally if cost rather than speed is the concern you ship by boat. Shipping by rocket over a plane would just be another higher tier of service. If Musk's pricing is to be believed it would make shipping between continents potentially faster than shipping within the continent. That would change the industry.

[thesash]

The loss rate for manned space launches over the past 20 years has been 0.79%. What you're pointing out (only once every few decades) is a factor of the small number of manned launches per year. Actual loss rate is very high. 1/130 chance of loss.

[agildehaus]

Most (all?) of that rate provided by the shuttle program and by early vehicles from the 60s and 70s.

Mercury + Gemini + Apollo had a 0% death rate in-flight. Not that they didn't come very close.

The shuttle had numerous design flaws. The use of solid fuel. A booster that was assembled in seven different sections, fastened, and sealed with rubber o-rings. Go-fever. Foam insulation that was known to fall off and strike the orbiter during launch.

Not that space flight isn't dangerous. My point is we can do a lot better with proper designs and attitudes. SpaceX also gets to examine and improve their stages in a way that has never been possible now that they come back in one piece.

[ncallaway]

> is a factor of the small number of manned launches per year

That's true, but the person you're replying to spent most of their comment directly addressing that fact.

[thesash]

What am I missing that addresses the math?

[Cerium]

That you will always have at least single digit failures. Sometimes things have to go wrong before we can correct them. We got where we are today with airplanes not because the first million flights didn't have a single accident, but because we paid careful attention to every failure and did our best to keep it from ever happening again.

Take a look at this report on Boeing crash history: http://www.boeing.com/resources/boeingdotcom/company/about_b... In particular, take a look at page 17 (slide 16) which shows the crash rate over time. We have gone from about 40 hull losses per million departures in the 50's to about 0.6 to 1 (depending on how you count) per million departures today.

[justin66]

> the loss rate for rockets

I wonder how you constructed that comparison such that it seemed meaningful. I'm pretty sure the lesson when you look at the data would be "fly on a man-rated Soyuz, not a Space Shuttle."

[thesash]

Loss rate for Space Shuttle program was 1.5%

135 missions, 2 lost.

http://www.popularmechanics.com/space/a6611/us-space-shuttle...

[justin66]

Do you see that as an indictment of the safety of manned space flight, or the safety of that vehicle? (you do understand that the modern Soyuz is quite safe, right? One can expect SpaceX's stuff to be safer.)

[planteen]

Are you looking at failures per mission or fatalities per person-trip? I thought the shuttle and Soyuz were very close on the fatalities per person-trip metric.

[justin66]

I'm surprised by that. They haven't lost a Soyuz crew since 1971, and they've flown quite a few.

(Soyuz capsules have had one or two pretty hard landings that I'm aware of. That's a failure mode that the newer capsules probably won't have.)

[planteen]

I can't quickly find a source, but back of the envelope is there have been 134 Soyuz manned missions. The number of people varies 1-3, most often 3 but occasionally 2. There were 135 Shuttle manned missions. Number there varied between 2-7, but ballpark looks like 6 was common.

So if we say 3 x 134 on Soyuz, there are 402 person-trips and 6 x 135 on Shuttle it is 810 person-trips. There were 4 Soyuz fatalities and 14 on the shuttle. So Soyuz fatality rate is about 1/100 and the shuttle is 1/56. So maybe it is closer to a factor 2 of difference.

The fatal mission rate is nearly identical (both have 2 fatal missions each).

https://en.wikipedia.org/wiki/List_of_Russian_manned_space_m... https://en.wikipedia.org/wiki/List_of_Soviet_manned_space_mi... https://en.wikipedia.org/wiki/List_of_Space_Shuttle_missions

[dvdhnt]

In the video, Musk states that SpaceX believes BFR will match the safety of commercial airliners due to its multi-engine propulsive landing capability.

[thesash]

Yes, totally, I get that they have a plan to make it safer -- my point is that a 20,000x increase in saftey is a massive leap, and that will be the limiting factor for this technology.

[dvdhnt]

Oh, right. I don't disagree with your sentiment, I was just adding information for HNers who didn't actually watch the video.

Consistently, my colleagues have made remarks along the lines of "I'll take the 1,000th flight after I know it's safe enough". I grew up with cars and airliners so I'm not sure what the process of convincing the public of BFR's safety will actually look like or how long it will take. For all I know, they'll give out the first 100 rides for free or at huge discounts, making all of these thoughts moot.

Cheers.

[sillysaurus3]

Well, your comparison isn't too fair. It seems like you're using the loss rates for modern aircraft capabilities. This is roughly like comparing the crash rates of modern OS's to early Unix.

To put it another way, it seems likely that the safety will increase by that much. Before airplanes, hang gliders were one of the most popular ways to fly, along with balloons. Gliders were incredibly unsafe, because pilots were expected to control the glider by shifting their body weight. This made stalls fatal, since you couldn't recover.

[thesash]

Again, I'm not saying it's not possible I'm saying that it's going to be really, really hard and that saftey is the critical path to making this viable. I'm sure they are spending all of their time and resources devoted to improving saftey. I'm just pointing out the ridiculousness of focusing the PR on time savings and cost parity when the saftey deficit is currently massive.

[nradov]

Fair has nothing to do with it. Civilians aren't going to pay for tickets on a rocket that they perceive as unsafe just to save a few hours. Those rockets will have to go years carrying cargo (or maybe military personnel) with zero crashes before the FAA will be willing to certify them for carrying paying commercial passengers.

[Florin_Andrei]

> There are three things that would factor into my decision about whether to strap myself to a rocket rather than fly in a plane: time, cost, and safety.

It's a valid concern, but it's only a matter of time before each new technology is perfected and made safe.

The exact same debates took place when Stephenson built his locomotive.

[grey-area]

Reusability and greater frequency will change these calculations radically. Similar statements to yours were made about flight in early airplanes, which was also dangerous.

[cjsuk]

It's less likely and a far better way to go than cancer :)