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Nikxice
Active Member
The investigation into April's Crew Dragon anomaly looks to be almost wrapped. Hardware and software fixes are apparently in the works. Most media reports still lean towards early 2020 for the DM-2 launch, but hold on! The interesting takeaway from this article are those lingering parachute nags. NASA’s Aerospace Safety Advisory Panel (ASAP) is still looking for more chute tests from both SpaceX and Boeing. There's also no definite timeline to reach achieve satisfactory results. Until approved, there's plenty of gray area attempting to speculate what the launch dates will be for either Commercial Crew operator.
SpaceX highlights Crew Dragon SuperDraco thrusters as explosion investigation nears end
SpaceX highlights Crew Dragon SuperDraco thrusters as explosion investigation nears end
I find the acronym for NASA’s Aerospace Safety Advisory Panel ironic in the extreme.
They really are obsessing about the chutes.
They really are obsessing about the chutes.
Nikxice
Active Member
Not confirmed by SpaceX, Business Insider is claiming Elon's presentation will start around 7:00 CDT, Boca Chica local time.
Meanwhile, is Jim Bridenstine feeling some heat from the top? Yesterday he felt compelled to issue a slight dig. He'd probably prefer a little less enthusiasm. Quite is better, like the lack of information concerning Boeing's Starliner abort system fuel leak. I'm sure that NASA is also frustrated by the long and expensive SLS delays. Though Jim isn't going to pass on an opportunity for some political gaslighting.
My statement on @SpaceX's announcement tomorrow:
Meanwhile, is Jim Bridenstine feeling some heat from the top? Yesterday he felt compelled to issue a slight dig. He'd probably prefer a little less enthusiasm. Quite is better, like the lack of information concerning Boeing's Starliner abort system fuel leak. I'm sure that NASA is also frustrated by the long and expensive SLS delays. Though Jim isn't going to pass on an opportunity for some political gaslighting.
My statement on @SpaceX's announcement tomorrow:
.5 mi / 7.5s = 107 m/s. Assuming smooth acceleration (Which it probably isn't), 107m/s / 7.5s = 14m/s/s / 9.8m/s/s = 1.5G. My guess though that acceleration is not constant. It's probably higher at the start to get the crew away quickly, but lower acceleration during sustained flight to balance comfort and safety.
107 m/s is 239 mph so yeah non-linear (even though they didn't say peak velocity of 436mph was reached in 7.5s i'll infer it)
107 m/s is 239 mph so yeah non-linear (even though they didn't say peak velocity of 436mph was reached in 7.5s i'll infer it)
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Simplest calculation:
436MPH/7.5s=58MPH/s=85ft/s^ 2/32ft/s^2 =2.7Gs.
Assuming constant force, less Gs at start and more at end. That effect depends on ratio of Super Draco propellant to Dragon mass.
This number is also the peak G force at MECO for a Dragon per /r/SpaceX Ask Anything Thread [August 2016, #23] : spacex
Shuttle launch was around 3 Gs.
Fighter ejection seats are 20 Gs or so.
Your math is better than mine. I couldn't be bothered to go back and redo the numbers when it was apparent my ending speed didn't match the quote 
(edit: I should also point out how non-linear the actual acceleration will be just due to the rocket equation, i.e. that mass is dropping constantly til the motors burn out, so my numbers are pretty far off)
(and this, folks, is why I never did very well in physics)
(edit: I should also point out how non-linear the actual acceleration will be just due to the rocket equation, i.e. that mass is dropping constantly til the motors burn out, so my numbers are pretty far off)
(and this, folks, is why I never did very well in physics)
Your math is better than mine. I couldn't be bothered to go back and redo the numbers when it was apparent my ending speed didn't match the quote
(edit: I should also point out how non-linear the actual acceleration will be just due to the rocket equation, i.e. that mass is dropping constantly til the motors burn out, so my numbers are pretty far off)
(and this, folks, is why I never did very well in physics)
Your issue is the the 107m/s is average velocity, double that for the peak/ ending velocity(with contant acceleration). 239×2=478 really close to 436. 1.5x2 = 3ish.
e-FTW
New electron smell
SpaceX crew testing out the emergency escape from the tower: NASA Commercial Crew on Twitter
But they did not actually ride the baskets down. Sad face.
NASA, SpaceX Test Pad Emergency Egress System – Commercial Crew Program
See, THIS is actual news shared on Twitter about the Crew program. Nothing else of note that I can find, ok JB? /rant
But they did not actually ride the baskets down. Sad face.
NASA, SpaceX Test Pad Emergency Egress System – Commercial Crew Program
See, THIS is actual news shared on Twitter about the Crew program. Nothing else of note that I can find, ok JB? /rant
I would not describe that statement by Bridenstine that way. I think it’s a slam on SpaceX and it’s over the line. Bridenstine is basically saying that SpaceX is not giving proper attention and resources to Crew Dragon but is instead focusing on Starship. Which strikes me as ridiculous. I’m sure that the Crew Dragon team is doing everything they can to accomplish their objectives and we have no evidence that resources are being diverted to Starship.
Indeed!
From tonight's talk, Elon said only 5% of resources are directed toward Starship.
Yes, I noticed that, and thought Elon was being very diplomatic in his response.
I don’t know what motivated Bridenstine to publicly criticize SpaceX’s Starship efforts as hindering Crew Dragon development and slowing down the CCT timeframe. Because that is exactly what his statement meant. I would point out that Boeing’s progress is at about the same place as SpaceX’s, but I don’t see Bridenstine slamming Boeing in public.
I’m trying not to read too much into what Bridenstine said, but it concerns me.
I missed the first several minutes of the Q&A last night because when Elon’s formal — that’s stretching the term — presentation ended I thought the webcast was over. I immediately went to this forum to check for comments and saw one indicating that Elon was taking questions, so got back on the webcast. Reading an NYT article just now I saw this that related to what Bridenstine said, quote:
———————————————————-
On Saturday, Mr. Musk responded that the “vast majority” of SpaceX’s resources are focused on its existing spacecraft, including Crew Dragon, and setting launch dates was up to NASA at this point.
“The NASA administrator was like ‘What’s going on? Are you not working on Crew Dragon or something?’ in that tweet,” Mr. Musk said during the post-event interview. “Actually, there’s nothing more we can do from a hardware standpoint. The hardware is basically done. It’s really just a whole bunch of NASA reviews, essentially. Speed up the NASA reviews, we can launch sooner.”
————————————————————
I’m glad that Elon responded to clarify the situation with Crew Dragon.
— presentation ended I thought the webcast was over. I immediately went to this forum to check for comments and saw one indicating that Elon was taking questions, so got back on the webcast. Reading an NYT article just now I saw this that related to what Bridenstine said, quote:———————————————————-
On Saturday, Mr. Musk responded that the “vast majority” of SpaceX’s resources are focused on its existing spacecraft, including Crew Dragon, and setting launch dates was up to NASA at this point.
“The NASA administrator was like ‘What’s going on? Are you not working on Crew Dragon or something?’ in that tweet,” Mr. Musk said during the post-event interview. “Actually, there’s nothing more we can do from a hardware standpoint. The hardware is basically done. It’s really just a whole bunch of NASA reviews, essentially. Speed up the NASA reviews, we can launch sooner.”
————————————————————
I’m glad that Elon responded to clarify the situation with Crew Dragon.
In a CNN interview last night, the reporter brought up the Bridenstine statement quoting “Commercial crew is years behind schedule.”
Elon’s tongue-firmly-in-cheek response: “Did he say Commerical Crew or SLS?”
Elon’s tongue-firmly-in-cheek response: “Did he say Commerical Crew or SLS?”
So, now NASA seems to want to pick a fight with SpaceX. Bridenstine's odd comment on the eve of Elon's Boca Chica unveiling of Starship:
Jim Bridenstine on Twitter
Eric Berger of Arstechnica isn't having any of it with his well written article today (the NASA spat showing up on page 2):
Elon Musk, Man of Steel, reveals his stainless Starship
Obviously NASA does like SpaceX since it keeps giving it contracts. But what was the point of Bridenstine's tweet? If anything, it allows people, like Eric Berger, to point out how wasteful NASA has been with SLS. I don't know, maybe Brindenstine is playing 8 dimensional chess here and that was the outcome he was hoping for.
Jim Bridenstine on Twitter
Eric Berger of Arstechnica isn't having any of it with his well written article today (the NASA spat showing up on page 2):
Elon Musk, Man of Steel, reveals his stainless Starship
Obviously NASA does like SpaceX since it keeps giving it contracts. But what was the point of Bridenstine's tweet? If anything, it allows people, like Eric Berger, to point out how wasteful NASA has been with SLS. I don't know, maybe Brindenstine is playing 8 dimensional chess here and that was the outcome he was hoping for.
I don’t think that is the explanation. His tweet was squarely aimed at SpaceX. I think it is possible that Bridenstine was being directed by a higher authority...
e-FTW
New electron smell
Daaaaamn son!In a CNN interview last night, the reporter brought up the Bridenstine statement quoting “Commercial crew is years behind schedule.”
Elon’s tongue-firmly-in-cheek response: “Did he say Commerical Crew or SLS?”
Clearly, those side-interviews are more revealing of what he thinks.
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