totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

I did test the biconic, four-brake entry in KSP.

It works quite well for how much limited control I was able to exercise. KSP's SAS engine doesn't understand what's happening, so the surfaces don't really work via SAS. I had to bind each control surface to an action group and toggle that way, and this meant no fine control authority.

Forward and aft flaps are both elevons set perpendicular to the axis of the vehicle.

Execute deorbit burn, then use RCS to rotate around to prograde, then SAS hold. Pitch up to radial-out as you cross 70 km. Set all flaps to maximum lateral extension (launch position for forward flaps; ~45 degree deflection from landing position for aft flaps).

During descent, hold AoA at approximately 75 degrees and damp roll. Use the following controls:

• To pitch up, feather the aft flaps dorsally, away from landing position, and feather the forward flaps ventrally to maximum lateral extension.
• To pitch down, feather the forward flaps dorsally and feather the aft flaps ventrally to max lat ext.
• To cancel clockwise roll, feather both port flaps dorsally and hold both starboard flaps at max lat ext.
• To cancel counterclockwise roll, feather both starboard flaps dorsally and hold both port flaps and max lat ext.

Care should be taken to avoid dropping AoA below 40 degrees. At roughly 40 degrees, the aft flaps come out of stall and begin to develop lift, kicking the tail up and turning the whole vehicle into a lawn dart. You have NO differential braking authority without a high AoA. Entry works best if you maintain forward flaps at maximum lateral extension and use the aft flaps for primary pitch control. This allows some degree of combined pitch/roll authority, because you can control pitch with the aft flaps while damping roll with the forward flaps.

Yaw authority is possible if you lower AoA to around 50 degrees, so that the aft flaps develop stall lift (still no laminar flow) and then brake differentially. For port yaw, maintain lateral extension on the port forward and starboard aft flaps but feather the other two dorsally; this will point the small control surface lift vectors in the direction you want. For starboard yaw, reverse.

With four differential braking surfaces, the landing flip is a breeze. Extend the forward flaps and feather the aft flaps to full dorsal position, which pitches you up into a body-lift stall and orients the engines retrograde. Throttle up, and all control surfaces stop interacting with the airstream as you complete the landing burn. Rotate the aft flaps forward into landing position and land.

[Spaceception]

This article was interesting. I was expecting technical reasons, but it was just about the social nature.

https://longreads.com/2018/09/19/were-not-ready-for-mars/

There are good points - We have serious problems here - But those have been said many times before - There's no guarantee the resources extracted will be used for all of us - some people have greedy intentions, etc.

But I don't see how colonizing other planets will be saving our planet. Those are two separate things which we will do in parallel.

I do think we should acknowledge our problems, correct our mistakes of the past, and correct/improve ourselves along the way. But becoming something akin to "inward perfectionists" seems a bit extreme to me. Adding to that (I had a conversation about this topic of space colonization yesterday): We would have to be at it for a long time before we "ruin space". I think we'd actually need to be trying in order to ruin it. One of my points in the conversation was: "Humanity is pretty awesome when you're not looking for reasons to hate it. Look how far we've come. The things we've created. How much we've grown. How far we could go."

After reading the article, I think I would be close to the type of person, or exact type of person he talks about in the article. But we shouldn't stunt ourselves because we aren't perfect. Which after reading this quote (And others);
"I am saying that to preach that Mars will save Earth while we wreck, ravage, and scorch Earth with no sense of spiritual decorum or ecological humility, and somehow then expect that space won’t be wrecked ravaged and scorched too is completely misguided. "
I think that is almost how the author thinks humanity should be before attempting to colonize the cosmos - perfect, or closer to perfect - And if we have to consider ourselves perfect/worthy or similar of colonizing space, then I think we'll have become an incredibly egotistical species by that point. Even more than the author thinks we are now.

 

Anyway, hope I made sense, do you guys agree or disagree with the article?

Edited September 19, 2018 by Spaceception
Not necessary to the conversation

[sevenperforce]

44 minutes ago, Spaceception said:

This article was interesting. I was expecting technical reasons, but it was just about the social nature.

https://longreads.com/2018/09/19/were-not-ready-for-mars/

There are good points - We have serious problems here - But those have been said many times before - There's no guarantee the resources extracted will be used for all of us - some people have greedy intentions, etc.

<snip>

Anyway, hope I made sense, do you guys agree or disagree with the article?

Ugh. I agree with you and disagree with the article.

"...astronaut David Scott intentionally left a simple plaque the size of a beer coaster with the names of astronauts and cosmonauts that perished in the space race on the lunar surface. Charles Duke left a family portrait encased in plastic. Astronaut Alan Shepard decided to drive a pair of golf balls across the surface of the moon. Apparently for kicks, astronaut Edgar Mitchell hurled one of the support rods of a solar wind collector like a javelin through the lunar atmosphere. All these astronauts peed into sacks called urine bags then discarded them on the moon. (It reminds me of guys at a bachelor party in New Orleans.) Twelve men have walked on the moon, and zero women. It shows. The moon has become the solar system’s largest bro playground."

Moralizing, self-aggrandized, self-righteous claptrap.

[Mitchz95]

[Starwaster]

7 hours ago, sevenperforce said:

It sounded a little odd when Elon made statements about "yeah it is riskier but I like the aesthetics," but on review I think that's looking more holistically. The risk is development risk, not operational risk; it's risky to force landing gear and control surfaces to develop as a single unit because if you can't do it then you've wasted a lot of time. And the aesthetics probably include stuff like simplicity, functionality, and so forth.

There's a lot of odd things Elon says and sometimes I think it's nervousness or anxiety on his part and sometimes I think he doesn't really know what he's talking about. He's knowledgeable for sure but he's not an engineer. I know he thinks of himself as one but he's not.

Case in point: When he says that dorsal fin isn't really functional? Don't take that very seriously. Maybe most of the time it's not really needed, but if BFR needs stabilizing in a hurry and they tuck both of the actuated wings in, trust me, that dorsal fin is going to be very aerodynamically significant. 

[tater]

 

[magnemoe]

9 hours ago, tater said:

Aft cargo was a thing for Shuttle, too, they just never did it:

(shaded area on the aft side of the external tank)

Nice, but the shuttle setup was mostly for oversize payloads. Looks like the BFR one is for either secondary payloads or ground equipment. the cells looks a bit small for rovers and drill rigs however. 
And as one above stated you could probably put in some SRB with short burn time for better abort performance. Abort is also part of the reason why they went for 7 sea level engines. With the bonus of having more  ground level trust for testing of the BFS in suborbital flights. 

Why is the BFR longer, is it longer first stage or upper stage, if upper is it more fuel or larger crew or cargo compartment. 
And yes for the tanker you want vacuum engines here you don't need abort option either, you would want an option to install vacuum engines later that is long enough rear area and an way to mount their interface.
It would be practical to use aging cargo BFS as tanker, add 150 ton extra fuel in cargo compartment 

[mikegarrison]

8 hours ago, Spaceception said:

This article was interesting. I was expecting technical reasons, but it was just about the social nature.

https://longreads.com/2018/09/19/were-not-ready-for-mars/

There are good points - We have serious problems here - But those have been said many times before - There's no guarantee the resources extracted will be used for all of us - some people have greedy intentions, etc.

But I don't see how colonizing other planets will be saving our planet. Those are two separate things which we will do in parallel.

I do think we should acknowledge our problems, correct our mistakes of the past, and correct/improve ourselves along the way. But becoming something akin to "inward perfectionists" seems a bit extreme to me. Adding to that (I had a conversation about this topic of space colonization yesterday): We would have to be at it for a long time before we "ruin space". I think we'd actually need to be trying in order to ruin it. One of my points in the conversation was: "Humanity is pretty awesome when you're not looking for reasons to hate it. Look how far we've come. The things we've created. How much we've grown. How far we could go."

After reading the article, I think I would be close to the type of person, or exact type of person he talks about in the article. But we shouldn't stunt ourselves because we aren't perfect. Which after reading this quote (And others);
"I am saying that to preach that Mars will save Earth while we wreck, ravage, and scorch Earth with no sense of spiritual decorum or ecological humility, and somehow then expect that space won’t be wrecked ravaged and scorched too is completely misguided. "
I think that is almost how the author thinks humanity should be before attempting to colonize the cosmos - perfect, or closer to perfect - And if we have to consider ourselves perfect/worthy or similar of colonizing space, then I think we'll have become an incredibly egotistical species by that point. Even more than the author thinks we are now.

 

Anyway, hope I made sense, do you guys agree or disagree with the article?

The article has a few good points. It is true that when people visit some place like this, usually the first thing they do is leave garbage. But it's hardly a sign of "modern American culture". When we dig up places where people (or near-people) lived hundreds of thousands of years ago, do you know what we find? Their garbage piles. (Except we call them "middens", which is a little classier of a name than "trash".)

Also, I'm sorry, but it's liberal arts woo-woo stuff to say, "The moon is a center of magic and mystery for virtually every culture on earth." No, the moon is a large chunk of rock that if in orbit around the Earth. It's not magic. People shouldn't confuse their own fuzzy view of the universe with reality.

In years past, the American wilderness was considered so vast that there were no ethics about stuff like dumping garbage in it. When I was a little kid, it was considered somewhat acceptable when backpacking just to throw trash into the bushes or bury it, because out-of-sight was out-of-mind. Then in the later 70s the attitudes changed and the ethos became "leave no trace" and "pack it in, pack it out". All in all, these are good changes. I can't imagine now just dumping trash in the wilderness like we used to.

But the moon or Mars? Those still seem vast and empty. So we leave a few rovers lying around. It's not like anybody is there to trip over them. Maybe someday we'll decide that the Moon or Mars is a wilderness that should be protected, but we're just not at that stage yet. It's not "bro culture" -- it's really just an example of entropy. It takes work to preserve a wilderness at the same time as you visit it, and there is so much of the moon that is untouched that it just doesn't seem like that level of effort is justified right now.

[insert_name]

9 hours ago, sevenperforce said:

Ugh. I agree with you and disagree with the article.

"...astronaut David Scott intentionally left a simple plaque the size of a beer coaster with the names of astronauts and cosmonauts that perished in the space race on the lunar surface. Charles Duke left a family portrait encased in plastic. Astronaut Alan Shepard decided to drive a pair of golf balls across the surface of the moon. Apparently for kicks, astronaut Edgar Mitchell hurled one of the support rods of a solar wind collector like a javelin through the lunar atmosphere. All these astronauts peed into sacks called urine bags then discarded them on the moon. (It reminds me of guys at a bachelor party in New Orleans.) Twelve men have walked on the moon, and zero women. It shows. The moon has become the solar system’s largest bro playground."

Moralizing, self-aggrandized, self-righteous claptrap.

I bet that if there is anything left of those urine bags on the moon they will be put in a museum along with every other scrap of trash left there

[magnemoe]

9 hours ago, sevenperforce said:

Ugh. I agree with you and disagree with the article.

"...astronaut David Scott intentionally left a simple plaque the size of a beer coaster with the names of astronauts and cosmonauts that perished in the space race on the lunar surface. Charles Duke left a family portrait encased in plastic. Astronaut Alan Shepard decided to drive a pair of golf balls across the surface of the moon. Apparently for kicks, astronaut Edgar Mitchell hurled one of the support rods of a solar wind collector like a javelin through the lunar atmosphere. All these astronauts peed into sacks called urine bags then discarded them on the moon. (It reminds me of guys at a bachelor party in New Orleans.) Twelve men have walked on the moon, and zero women. It shows. The moon has become the solar system’s largest bro playground."

Moralizing, self-aggrandized, self-righteous claptrap.

This match so well with the target profile that the profile can be ignored for being an Moralizing, self-aggrandized, self-righteous prick. 
Any discussion with profile would be pointless, that unless you can point of how radically the profile real life separates from his preaching. 

 

8 hours ago, Mitchz95 said:

Obvious follow up. 

[tater]

 

(to reach 42)

[CatastrophicFailure]

Now that’s... interesting... 

ETA: Wait, I get it, took me a minute. 

Edited September 20, 2018 by CatastrophicFailure

[Bill Phil]

20 minutes ago, tater said:

 

(to reach 42)

That sounds like the number of engines ITS had on the booster...

[tater]

Thinking a hitchhikers joke.

[Nightside]

8 minutes ago, tater said:

Thinking a hitchhikers joke.

Come to think of it, Elon has been acting a lot like Zaphod Beeblebrox lately.

Shotwell better keep a tight hold of the keys to the BFS come launch day.

[RedKraken]

I may have the answer ....

https://rossbainesart.bigcartel.com/product/j-r-elon-fine-art-print-a1-a2-a3

[Bill Phil]

52 minutes ago, tater said:

Thinking a hitchhikers joke.

Probably. No reason it couldn't be something else as well.

38 minutes ago, Nightside said:

Come to think of it, Elon has been acting a lot like Zaphod Beeblebrox lately.

Shotwell better keep a tight hold of the keys to the BFS come launch day.

Will the first one be called Heart of Gold? If so...

[Ultimate Steve]

6 minutes ago, Bill Phil said:

44 minutes ago, Nightside said:

 

Will the first one be called Heart of Gold? If so...

The first (or the first manned) BFS to go to Mars will be called Heart Of Gold, but not the first ever, according to Elon.

[CatastrophicFailure]

1 hour ago, Ultimate Steve said:

The first (or the first manned) BFS to go to Mars will be called Heart Of Gold, but not the first ever, according to Elon.

The first cargo ship needs to be called Planet Express Ship.  

[Nightside]

29 minutes ago, Ultimate Steve said:

The first (or the first manned) BFS to go to Mars will be called Heart Of Gold, but not the first ever, according to Elon.

He’s definitely planning to steal his own spaceship.

[StarStreak2109]

On 9/18/2018 at 11:37 PM, zolotiyeruki said:

During the presentation last night, did anyone else feel like Elon was acting a bit...odd?  Hesitant, stilted speech, odd pauses, etc.

 

On 9/18/2018 at 11:51 PM, CatastrophicFailure said:

Naw, that’s how all of his presentations are.   A gifted speaker he is not. 

Well, he never was a good public speaker. He always stammered a bit, searching for words. There are a couple of things though, that I noticed, which also fits in the recent reports on his "behaviour":

• He looked quite tired, worn out. Puffy around the eyes, face a bit swollen. That looks to me like a combination of huge workload, not enough sleep and some pretty significant stim intake to compensate, probably combined with too much unhealthy food and drink.
• At the beginning, he seemed quite anxious, lost for words. Later on it got better, to the brink of boyish behaviour. Stims kicking in?
• He always had this attitude, that was a bit childish at times, were he jokingly introduced all his wild ideas, like a good nerd. This time I think, it went a bit overboard. He just secured a major portion of his dev funding for BFR and he did not act like it. If I were in his shoes, I'd have felt embarrassed.

So yeah, it seems that all the excrements he keeps piling around him recently ("pedo guy" affair, Tesla privatisation (or not), Tesla production / delivery hell, Boring company, hyperloop, ...), slowly but surely gets to him. He'd better be careful not not kill himself with this unhealthy lifestyle.

However, all these facts do not diminuish his accomplishments. Looking forward to more BFR developments...

[StarStreak2109]

Further notes on this whole BFR thing, my personal impressions:

• BFR is still very much an engineering concept only, along with some basic feasibility studies. Much development work will have to go in the spaceframe itself, but more importantly in all the nitty gritty details (ECLSS, EDL, interior design*,...). Let's call basic design.
• The basic design will definitely bring significant changes to the spaceframe itself as the various components are being developed and integrated into the whole system 'BFR'. Some ideas that float around now will be discarded as being unfeasible, others will be added and so on.
• After the first test missions, they will need to do a detailed design, which will integrate lessons learned from the testing. Again, with potentional changes, probably mostly under the hood.
• What I am trying to say is that the BFR which will eventually fly, might look drastically different from what we saw now.
• Moreover, there are still no current and reliable infos on reusability (did I see tiles on the heat shield???), on costs, on mission profiles, on-orbit refueling, abort systems, you name it.

TL;DR: I do not know how far advanced the BFR prototype construction has gone beyond that single part they showed in the presentation, but if they really want to start tests soon, it's gonna be tight. I rather see the first moon mission in 2025 to 2027 at the earliest, especially since so many of the BFR systems are depending on prior experience from Dragon 2 with regards to life support etc.

If I were SpaceX, I'd not only look to people like this Japanese chap, who seems pretty willing to pay probably in the range of 150 M$ as venture capital**, but I'd also look at public/other corporate funding to find future customers who are willing to participate in BFR development, probably with the option to introduce features that benefit them as well.

[Xd the great]

8 hours ago, RedKraken said:

I may have the answer ....

https://rossbainesart.bigcartel.com/product/j-r-elon-fine-art-print-a1-a2-a3

Did he get addicted to it?

[Green Baron]

Surely not, but smoking ganja in the late 40s is a severe case of losing the sense for reality, even more so in his situation. It shows a childish attitude of a phase of life most people leave behind at 18-22 (or earlier) ...

Edited September 20, 2018 by Green Baron

[sh1pman]

27 minutes ago, Green Baron said:

Surely not, but smoking ganja in the late 40s is a severe case of losing the sense for reality, even more so in his situation. It shows a childish attitude of a phase of life most people leave behind at 18-22 (or earlier) ...

Ah, but you’re wrong on that. I know quite a few people in their 40s who smoke weed occasionally. Most of them are business owners or otherwise well-off people. It’s just their way of dealing with stress, and I can’t say it affects their sense of reality in any negative way.