Early crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.
Quote from: RonM on 10/06/2017 08:12 pmEarly crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.
Quote from: DJPledger on 10/06/2017 08:26 pmQuote from: RonM on 10/06/2017 08:12 pmEarly crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you. Rather than repeating yourself, give some reasons beyond "it's a must".
Quote from: Lar on 10/06/2017 08:48 pmWhy is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you. Rather than repeating yourself, give some reasons beyond "it's a must". Launching crew is still a high risk activity which is why all current crewed launches have a LAS. I think SpX needs to get the LOC risk down to around 1 in 100,000 to 1,000,000 for the BFR to be deemed safe enough to not have a LAS. This safety factor for BFR may be possible a long way down the road but unlikely to be achieved during the first few years of BFR service life.Just one LOC event could kill SpX.
Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you. Rather than repeating yourself, give some reasons beyond "it's a must".
Quote from: DJPledger on 10/06/2017 08:59 pmQuote from: Lar on 10/06/2017 08:48 pmWhy is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you. Rather than repeating yourself, give some reasons beyond "it's a must". Launching crew is still a high risk activity which is why all current crewed launches have a LAS. I think SpX needs to get the LOC risk down to around 1 in 100,000 to 1,000,000 for the BFR to be deemed safe enough to not have a LAS. This safety factor for BFR may be possible a long way down the road but unlikely to be achieved during the first few years of BFR service life.Just one LOC event could kill SpX.Proof by assertion..., isn't. This still is of the form "it's a must". Airliners do not have LAS, and didn't even back in the 1930s. Nor are passengers issued parachutes. Shuttle didn't have LAS. Just saying "well I don't care, BFS has to have one because everyone else does" isn't convincing.
Quote from: Lee Jay on 10/06/2017 07:32 pmAn airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes. Not having an abort system on a crewed vessel is a show-stopper.It has redundancy and large safety margins but not an escape system. There’s no parachutes onboard for all passengers. Any passengers actually.
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes. Not having an abort system on a crewed vessel is a show-stopper.
Current rockets aren’t as safe as airliners. They intend to demonstrate safety on the order of airliners.
Quote from: cppetrie on 10/06/2017 07:59 pm Current rockets aren’t as safe as airliners. They intend to demonstrate safety on the order of airliners.Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact. Last week an A380 had an uncontained engine failure and still landed intact with no people injured. I was aboard an airliner with a control-systems failure. We landed without issue. This sort of thing happens all the time. That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.
Airliners are so safe they don't need LAS. Shuttle not having LAS was a huge mistake with two LOC events. Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.
...Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.
Quote from: Lee Jay on 10/06/2017 09:24 pmQuote from: cppetrie on 10/06/2017 07:59 pm Current rockets aren’t as safe as airliners. They intend to demonstrate safety on the order of airliners.Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact. Last week an A380 had an uncontained engine failure and still landed intact with no people injured. I was aboard an airliner with a control-systems failure. We landed without issue. This sort of thing happens all the time. That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.And why can’t that be true for BFR?
Quote from: cppetrie on 10/06/2017 10:05 pmQuote from: Lee Jay on 10/06/2017 09:24 pmQuote from: cppetrie on 10/06/2017 07:59 pm Current rockets aren’t as safe as airliners. They intend to demonstrate safety on the order of airliners.Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact. Last week an A380 had an uncontained engine failure and still landed intact with no people injured. I was aboard an airliner with a control-systems failure. We landed without issue. This sort of thing happens all the time. That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.And why can’t that be true for BFR?Because it's not inherently flyable and because the energy levels are so much higher.Could it land in an all engines out situation? Airliners can and have. They have to be certified to do so.It is safe in a catastrophic rupture of the cabin? Airliners have landed safely after such an event.Can it land safely in a lake, river or ocean? People have survived that occurrence many times.Almost everything will have to go right for this thing to be safe to ride on.At the very least, the upper stage (or spacecraft, if you prefer) needs to be able to separate from a failing first stage and fly itself to safety. However, as I understand it, that isn't possible. Did I misunderstand that part?
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations. And, not being an engineer thus not understanding the technicalities as robotbeat does, the thing I can comment on is how irrational it seems to draw similar pessimistic conclusions when talking about rockets, machines that fly less then 100 times per year and are still in their infancy vs airliners. That will change with BFR and full reusability. Instead of making assumptions we should wait and see (or try and see, if you are an aerospace company: the sad thing is that after the Shuttle we had to wait for SX and BO for someone to do this).