Quote from: Rocket Science on 09/28/2016 12:57 pmQuote from: Nibb31 on 09/28/2016 08:09 amQuote from: Rocket Science on 09/28/2016 08:04 amIt's the wee hours of the morning here but did I miss something about no mention of abort modes?No you didn't. We can assume the BFS takes care of itself if the BFR fails. If the BFS fails, you're toast.Thanks, I didn't think so and when I couldn't sleep I checked NSF (you know your a space geek when...) All I recall was the engine out ability, but not having abort modes from pad to orbit also raises my brows thus-sly ...With 9 Raptors the spaceship could (in theory) do a pad abort to soft landing as soon as there's a minimum amount of LOX in the tank (probably around 10%). There would be a considerable number of technical hurdles to accomplish this, and it would under some conditions be a very slow abort, but the TWR of the fueled upper stage on the pad can be positive. Once in flight TWR isn't so critical as long the ship can maintain control authority. If the ITS tanker stage is used as a SSTO, it could carry Dragon 2 which has it's own pad to orbit abort abilities.
Quote from: Nibb31 on 09/28/2016 08:09 amQuote from: Rocket Science on 09/28/2016 08:04 amIt's the wee hours of the morning here but did I miss something about no mention of abort modes?No you didn't. We can assume the BFS takes care of itself if the BFR fails. If the BFS fails, you're toast.Thanks, I didn't think so and when I couldn't sleep I checked NSF (you know your a space geek when...) All I recall was the engine out ability, but not having abort modes from pad to orbit also raises my brows thus-sly ...
Quote from: Rocket Science on 09/28/2016 08:04 amIt's the wee hours of the morning here but did I miss something about no mention of abort modes?No you didn't. We can assume the BFS takes care of itself if the BFR fails. If the BFS fails, you're toast.
It's the wee hours of the morning here but did I miss something about no mention of abort modes?
Wowza. The ITS is one impressive rocket. 42 engines in the first stage. How many engines can fail and the rocket still get the Mars ship to a useful orbit? Elon said "multiple". I would expect each engine to be surrounded by shielding to prevent one Raptor RUD from taking out the others (like what happened with N-1?).As far as the ITS crewed vessel, one question that occurs to me is how much payload would it carry if it were just being launched by itself (SSTO) into a low earth orbit like the one Shuttle used? Elon said it was a small number. Better yet, how much of a payload would it carry on a suborbital flight, say from New York to London? If they test it on suborbital hops and find it can work well I wouldn't be surprised if Elon tries to make money by pioneering transoceanic suborbital cargo & passenger services, after all he'll need lots of income to pull this off. Speaking of tourism, if ITS really works and they fly people as far as Saturn I could see myself enjoying a tourist flight to see the rings of Saturn close up, if I make it out that far.....
What happens if your exploding stage 1 takes out your engines and gear on the pad or low altitude?
The Raptor engines "ramp-up" time is too long to be escape engines... YMMV...
any speculation about whether the first rocket to mars will have humans or will he try to setup isru with robotic assembly on mars? It seems it would be hard to setup the isru with robotics. OTOH first humans would have to live there years before the isru can make enough fuel for return.
Quote from: Rocket Science on 09/28/2016 01:09 pmWhat happens if your exploding stage 1 takes out your engines and gear on the pad or low altitude?The landing gear likely aren't needed for a soft landing - the Falcon 9 stages did soft water landings and floated for awhile. An explosion violent enough to take out multiple Stage 2 engines probably breaches the Stage 2 tanks, at which point the whole thing goes kabloomy. I don't see a Stage 2 tank breech during an on-pad booster anomaly being survivable, though it might be survivable if it happens in flight and those spheres inside the tanks hold landing prop.Getting the upper stage moving away quickly as soon as an anomaly is detected would be critical in any evert. And certainly difficult, but not impossible.
Although the Heart of Gold class or cargo variants that are meant for deep space missions need legs, Tankers or NEO Cargo shuttle variants don't if it's possible to normally land back on the launch stand. Why not apply that mass to something more useful? They could also put launch stands in the bullseye on ASDSs and skip the legs for sea landings too.
So I guess we are in agreement then that there is only "one" failure mode abort "if" the S2 engines and gear are not damaged and that is "abort to orbit". Any CRS-7 or AMOS-6 type event, for sake of discussion are impossible or "iffy" at best... Inline staging is not fool proof and the Shuttle side mount was not the only risky type architecture which is why Orion, Dragon 2 and CST-100 all have a dedicated LES...
This picture still blows me away, hours later.... I made some rough estimates of the tank diameter, using the people. (who also are of unknown height but the taller ones are likely ~6ft). Taking into account the perspective distortion of a wide angle lens, this tank is at least 10m wide. So since the geometry matches the spacecraft schematic, this could actually be a full size 12m diameter LOX tank for the spacecraft!
Also in the diagram of the spaceship I don't see where the solar panels are stowed. Still early days I guess.
Quote from: Rocket Science on 09/28/2016 01:36 pmSo I guess we are in agreement then that there is only "one" failure mode abort "if" the S2 engines and gear are not damaged and that is "abort to orbit". Any CRS-7 or AMOS-6 type event, for sake of discussion are impossible or "iffy" at best... Inline staging is not fool proof and the Shuttle side mount was not the only risky type architecture which is why Orion, Dragon 2 and CST-100 all have a dedicated LES...How many flights do you need to be confident enough not to have an abort strategy?How do you get that flight count on a brand new engine and launch system?
Quote from: envy887 on 09/28/2016 01:27 pmQuote from: Rocket Science on 09/28/2016 01:09 pmWhat happens if your exploding stage 1 takes out your engines and gear on the pad or low altitude?The landing gear likely aren't needed for a soft landing - the Falcon 9 stages did soft water landings and floated for awhile. An explosion violent enough to take out multiple Stage 2 engines probably breaches the Stage 2 tanks, at which point the whole thing goes kabloomy. I don't see a Stage 2 tank breech during an on-pad booster anomaly being survivable, though it might be survivable if it happens in flight and those spheres inside the tanks hold landing prop.Getting the upper stage moving away quickly as soon as an anomaly is detected would be critical in any evert. And certainly difficult, but not impossible.So I guess we are in agreement then that there is only "one" failure mode abort "if" the S2 engines and gear are not damaged and that is "abort to orbit". Any CRS-7 or AMOS-6 type event, for sake of discussion are impossible or "iffy" at best... Inline staging is not fool proof and the Shuttle side mount was not the only risky type architecture which is why Orion, Dragon 2 and CST-100 all have a dedicated LES...
I haven't read all the comments in this thread. But I sort of wonder what is the best way to describe the spacecraft, it seems like a cross between a capsule and a lifting body. It has a black heatshield on one side.
A steady demand of launch services from NASA (rather than its own HLV), DOD should reduce costs or other markets. If you remove HSF missions, it implies that DOD costs increase for the same mission set. Common configurations for Class A payload and higher flight rate provides demonstrated reliability--how does MCT fit in this regard?
Quote from: CapitalistOppressor on 09/28/2016 11:07 amThat is an entirely different beast than the base financial investment required to get the first people to Mars, which presumably would be quite a bit less than the $10b total. The actual amount Elon seems to expect SpaceX to spend over the next 8-10yrs is something on the order of ~$1.2-$2.4b, based on his assertion that he would ramp up spending to ~$200-$300m/yr starting in a couple of years. That isn't going to happen if his current cash flow is interrupted yearly. Musk said they'd do what they can, which in my mind implies that he was planning on saying more before events intervened. Even assuming SX was running 10% margins and spending half of that on Raptor dev, another 9+ month shutdown is going to erase a lot more than 10%. There are some lean years ahead imho. FH test is put off until a redundant pad exists because you can't risk your only pad. Some of those customers walk. Musk said that schedule was for if everything went right. It already hasn't. I suspect a full assess is waiting on finding what went wrong. I don't expect there'll be 9 figures of free cash flow in a couple of years, sadly.
That is an entirely different beast than the base financial investment required to get the first people to Mars, which presumably would be quite a bit less than the $10b total. The actual amount Elon seems to expect SpaceX to spend over the next 8-10yrs is something on the order of ~$1.2-$2.4b, based on his assertion that he would ramp up spending to ~$200-$300m/yr starting in a couple of years.