Quote from: Robotbeat on 07/17/2018 04:21 amI didn't understand every point you made there, but I do appreciate you pointing out that abort for BFS could achieve a better T/W if they lowered the propellant load for crew launches.This abort system doesn't work if is exploding 2nd stage you trying to escape.Which has been case with last 2 SpaceX failures.
I didn't understand every point you made there, but I do appreciate you pointing out that abort for BFS could achieve a better T/W if they lowered the propellant load for crew launches.
<snip of airplane-ish-like safety>I hope you are correct...but I doubt it. at Best SpaceX/Boeing will need a decade to get to a new place (at current flight rates)
Quote from: envy887 on 07/17/2018 08:12 pmQuote from: TrevorMonty on 07/17/2018 09:35 amQuote from: Robotbeat on 07/17/2018 04:21 amI didn't understand every point you made there, but I do appreciate you pointing out that abort for BFS could achieve a better T/W if they lowered the propellant load for crew launches.This abort system doesn't work if is exploding 2nd stage you trying to escape.Which has been case with last 2 SpaceX failures.Flight-qualifying each full vehicle and having full redundancy will mostly obviate the need for a LAS."flight qualifying"...what do you suggest that term means?Airplanes do not have "launch escape systems"...but before an airplane gets a type certificate the "test planes" get far far more testing by the manufacturer than any crewed space vehicle has flown probably in aggregate. we are in my view a long long way toward the equivalent type of "certification" in space vehicles...maybe decades
Quote from: TrevorMonty on 07/17/2018 09:35 amQuote from: Robotbeat on 07/17/2018 04:21 amI didn't understand every point you made there, but I do appreciate you pointing out that abort for BFS could achieve a better T/W if they lowered the propellant load for crew launches.This abort system doesn't work if is exploding 2nd stage you trying to escape.Which has been case with last 2 SpaceX failures.Flight-qualifying each full vehicle and having full redundancy will mostly obviate the need for a LAS.
The BFR 2nd stage is no safe than booster, same fuel, same engines. Just because there are no COPV doesn't mean its totally safe.
Planes don't carry tons of oxidiser and they don't explode mid flight unless hit with missile. The BFR 2nd stage is no safe than booster, same fuel, same engines. Just because there are no COPV doesn't mean its totally safe.
Quote from: TripleSeven on 07/15/2018 01:12 pmin a nutshell I agree with what you wrote...the difference in my thinking is that I dont think that SpaceX "Mars" thing is actually a business plan...its more well excitmentThe business plan for Mars is pretty straightforward. Sell launches to NASA. If the price is low enough it would be politically difficult for Congress to not pony up the funds. It's $400 hammer dollar politics. Everybody likes to be the one crusading against $400 dollar hammers so when you have an actual $400 hammer and you can find a $7 hammer to compare it with, it's the lowest hanging fruit of politics.
in a nutshell I agree with what you wrote...the difference in my thinking is that I dont think that SpaceX "Mars" thing is actually a business plan...its more well excitment
Quote from: TrevorMonty on 07/18/2018 07:44 pmThe BFR 2nd stage is no safe than booster, same fuel, same engines. Just because there are no COPV doesn't mean its totally safe.I'm old enough to remember when passenger airliners crashing was not unusual, so I don't think we should apply modern safety analogies to spaceflight.There will be accidents, and there will be deaths in spaceflight. Yet frequent airliner accidents and deaths just 40-50 years ago did not stop the flying public from using commercial air transport.Oh, and no commercial airliner ever had escape systems for the passenger to use while in flight. So let's keep perspective here...
How the safety of BFR jumps 5 orders of magnitude over the proven safety of all real launch vehicles is at best a mystery to me.
Quote from: Darkseraph on 07/18/2018 10:55 pmHow the safety of BFR jumps 5 orders of magnitude over the proven safety of all real launch vehicles is at best a mystery to me.Reuse. If they can fly it again and again and again they can get vastly more flight experience and make it safer. How many times does this need to be repeated?
SpaceX happens to be promoting BFR as a competitor to international air travel, therefore modern safety analogies are probably worth discussing. The chance of dying on any particular airplane flight are about 1 in 11 million. The chances of most launch vehicles failing is roughly 1 in 50. Boeing and SpaceX are struggling to meet a 1 in 270 Loss of Crew goal for commercial crew vehicles (this is WITH launch escape systems)
At best, that's wishful thinking.
Certainly the re-usability of Falcon 9 S1 is not improving their LOC numbers beyond 1 in 270, which they are struggling to meet. Reuse didn't do so for the shuttle either.
No reusable part of either the Shuttle or F9 had ever caused LOM, going on 190 flights now.
cQuote from: envy887 on 07/19/2018 03:11 amNo reusable part of either the Shuttle or F9 had ever caused LOM, going on 190 flights now.The loss of Columbia seems rather intimately tied to it's reusable hardware.
Planes don't carry tons of oxidiser and they don't explode mid flight unless hit with missile.
Quote from: TrevorMonty on 07/18/2018 07:44 pmPlanes don't carry tons of oxidiser and they don't explode mid flight unless hit with missile.TWA 800 fuel/air explosion.https://en.wikipedia.org/wiki/TWA_Flight_800Aloha 243 explosive decompression.https://www.aerotime.aero/yulius.yoma/18542-history-hour-aloha-airlines-flight-243-incident
I'm old enough to remember when passenger airliners crashing was not unusual, so I don't think we should apply modern safety analogies to spaceflight.There will be accidents, and there will be deaths in spaceflight. Yet frequent airliner accidents and deaths just 40-50 years ago did not stop the flying public from using commercial air transport.
The loss of Columbia seems rather intimately tied to it's reusable hardware.