totm nov 2023 SpaceX Discussion Thread

[Treveli]

5 minutes ago, Dale Christopher said:

if Crew Dragon was still viable to run post Starship then they could keep improving it sure. 

I've been thinking that Dragon and the Falcon 9s would still have a place even with Starship available. If you think of Starship as the semi-truck/bus of future space launches, there could still be times/payloads where the smaller pickup/taxi of Falcon-Dragon could be better suited.

Just makes me kinda sad to think Falcon and Dragon will get perfected just in time to be tossed aside for Starship.

[kerbiloid]

29 minutes ago, Wjolcz said:

The capsule would need legs though. So they would either have to certify it with legs from the start or modify each one of them after the first flight (since crew is going to fly only once on each of them).

I mean, without crew. Uncrewed Crew Dragon. As a proof of concept.

[Xd the great]

1 hour ago, magnemoe said:

Much harder to get it certified by NASA. One option might be parachutes and then use the super drakos to slow down to safe landing speeds kind of like Soyuz uses but liquid fuel.
However not sure this is much easier to certify. 

Probably easier to certify, as if the engines fail you are only going to get brusied, not killed.

But perhaps the engine exhaust may be unhealthy to the exiting astronauts and ground crew.

Edited December 31, 2019 by Xd the great

[Guest]

1 hour ago, Treveli said:

I've been thinking that Dragon and the Falcon 9s would still have a place even with Starship available. If you think of Starship as the semi-truck/bus of future space launches, there could still be times/payloads where the smaller pickup/taxi of Falcon-Dragon could be better suited.

Hmm, if Starship is substantially cheaper and able to launch much more crew/cargo on a faster timetable what is there left for Crew Dragon? special cases dictated by security or regulation maybe...

[tater]

The point of Starship is to be cheaper to operate than any flavor of Falcon 9. At that point, it doesn't matter that any F9 type (Dragon, fairing, whatever) is smaller. Only cheaper matters---or for crew, safety. I can see a long time where F9 stays around as a crew vehicle (with Crew Dragon) since it's human rated, until anyone feels comfortable riding on Starship.

[Wjolcz]

2 hours ago, Treveli said:

I've been thinking that Dragon and the Falcon 9s would still have a place even with Starship available. If you think of Starship as the semi-truck/bus of future space launches, there could still be times/payloads where the smaller pickup/taxi of Falcon-Dragon could be better suited.

Just makes me kinda sad to think Falcon and Dragon will get perfected just in time to be tossed aside for Starship.

Crew Dragon and F9 will be flying for at least a couple more years. It's probably not easy to get crew certification for what's basically a reusable, skydiving and hoverslaming Shuttle external tank with crew and/or payload on top.

2 hours ago, kerbiloid said:

I mean, without crew. Uncrewed Crew Dragon. As a proof of concept.

I know. But the current plan is to use Dragon 2 for crew once and then they become cargo BUT to make propulsive landing possible it would need modifications (legs and probably a couple more other things). To make that happen you either build a whole new version of D2 with legs and certify it AGAIN for crew OR retrofit each D2 with legs after the first flight. Both options add cost and work for what seems to be miniscule return/savings. Don't get me wrong because I would love to see that, it's just that SpaceX isn't interested in doing this anymore for a reason.

Or maybe they could land it on its heatshield without any mods, but I'm really not sure if D2 internal and external structure can withstand that.

Edited December 31, 2019 by Wjolcz

[Ultimate Steve]

Also, if starship ends up being like 10 milliion per launch or more initially, it would be cheaper to send a small payload to gto or the moon with a falcon than it would be with a Starship due to the number of starship launches it would take due to refueling.

[CatastrophicFailure]

Worth getting up at zero-dark-thirty for 

 

[cubinator]

6 minutes ago, CatastrophicFailure said:

Worth getting up at zero-dark-thirty for 

If they webcast that, it'll probably be Jeb Kerman himself presenting. Big booms.

[sevenperforce]

3 hours ago, Wjolcz said:

Or maybe they could land it on its heatshield without any mods, but I'm really not sure if D2 internal and external structure can withstand that.

The structure can handle it with no problem, but there's a high tipover risk. 

[tater]

The weather is bad on the 3d, but the fallback 24 hours later is great for low level, but terrible for high level winds, so this makes sense.

[StrandedonEarth]

I think the biggest problem with D2 propulsive landing is the toxic hypergolics contaminating the landing area.

Perhaps Musk was a little short-sighted in abandoning further D2 evolution in favor of concentrating all resources on SS, since the road to man-rating SS will be a long one. Figuring out propulsive landing of D2 (with 'chute backup) for quicker turnaround may be worth more than he thought, if problems arise with SS.

The best path I see to accomplishing that is to convert the Draco/SuperDraco system  to G/L oxy with Rp-1 or methane, possibly battery-electric pump fed. I'm sure that's much more difficult than it sounds. Also, mount the landing legs similar to the SD pods, extending out and down, so they don't have to go through the heat shield

[Motokid600]

Why would the D2 need landing legs at all? Just plop down on the heat shield.

[Ultimate Steve]

39 minutes ago, StrandedonEarth said:

I think the biggest problem with D2 propulsive landing is the toxic hypergolics contaminating the landing area.

Perhaps Musk was a little short-sighted in abandoning further D2 evolution in favor of concentrating all resources on SS, since the road to man-rating SS will be a long one. Figuring out propulsive landing of D2 (with 'chute backup) for quicker turnaround may be worth more than he thought, if problems arise with SS.

The best path I see to accomplishing that is to convert the Draco/SuperDraco system  to G/L oxy with Rp-1 or methane, possibly battery-electric pump fed. I'm sure that's much more difficult than it sounds. Also, mount the landing legs similar to the SD pods, extending out and down, so they don't have to go through the heat shield

This would be difficult. It would be basically a whole new engine as you would need an actual ignition system, negating a lot of the launch escape system reliability. You also suggest non pressure fed which greatly increases the complexity of the system and again necessitates a vastly different engine. You would also need to prevent the rp1 or methane from freezing during the flight, and the oxygen from boiling off unless you used gaseous oxygen, but that requires far heavier tanks.

You would need to have whole new tanks as well as you aren't using the same system for rcs but that's probably not as big of a deal as the engines.

The escape engines would be far more complex than the other system and NASA would probably be very hesitant about using something that complex as an escape system. Plus if pump fed, the system will take longer to ignite because the pumps have to spin up.

The holes in the heatshield thing might be the easiest part, it was done on every space shuttle mission and I believe some or all of the unmanned VA flights.

Edit: Misread the post a bit, thought you emphasized pumps more than you did. Pressure fed is still possible but SpaceX doesn't really have the greatest experience with cold lox under pressure.

Edited December 31, 2019 by Ultimate Steve

[RealKerbal3x]

10 minutes ago, Motokid600 said:

Why would the D2 need landing legs at all? Just plop down on the heat shield.

The heat shield is curved. That could lead to the capsule tipping after landing and being damaged.

[magnemoe]

6 minutes ago, Ultimate Steve said:

This would be difficult. It would be basically a whole new engine as you would need an actual ignition system, negating a lot of the launch escape system reliability. You also suggest non pressure fed which greatly increases the complexity of the system and again necessitates a vastly different engine. You would also need to prevent the rp1 or methane from freezing during the flight, and the oxygen from boiling off unless you used gaseous oxygen, but that requires far heavier tanks.

You would need to have whole new tanks as well as you aren't using the same system for rcs but that's probably not as big of a deal as the engines.

The escape engines would be far more complex than the other system and NASA would probably be very hesitant about using something that complex as an escape system. Plus if pump fed, the system will take longer to ignite because the pumps have to spin up.

The holes in the heatshield thing might be the easiest part, it was done on every space shuttle mission and I believe some or all of the unmanned VA flights.

Edit: Misread the post a bit, thought you emphasized pumps more than you did. Pressure fed is still possible but SpaceX doesn't really have the greatest experience with cold lox under pressure.

As dragon has to stay docked with IIS for an long time they can not use LOX, and yes landing with hypergolics is also an problem, even softening a parachute landing. 
As for starship, either expect manned NASA missions to run on dragon and falcon 9 for most of this decade or start engineer an escape system for starship. Longer if you loose any outside the prototypes. 

4 minutes ago, RealKerbal3x said:

The heat shield is curved. That could lead to the capsule tipping after landing and being damaged.

Its a bit curved, main issue is wind with an parachute landing. I don't think legs will help much here 

[Xd the great]

3 hours ago, RealKerbal3x said:

The heat shield is curved. That could lead to the capsule tipping after landing and being damaged.

And we all know how good heatshields are against collisions...

Spoiler

Sorry crew of Columbia

Which brings me to the topic: how will Starship's tiles differ from those of space shuttle, so as to improve protection against microasteroids?

Edited January 1, 2020 by Xd the great

[magnemoe]

26 minutes ago, Xd the great said:

 

  Hide contents

Sorry crew of Columbia

Which brings me to the topic: how will Starship's tiles differ from those of space shuttle, so as to improve protection against microasteroids?

Better materials, so the tiles are more sturdy, also they will be mechanically fastened rather than glued and the backing as in steel can take fare more heat than the aluminium hull of the shuttle.
Result is that the tiles will crack rather than get destroyed or fall off and the backing can take much more heating. 

[Ultimate Steve]

Also this isn't directly what the question asked but there is far less chance of something breaking off and hitting the heat shield on starship than on the shuttle. Starship isn't on the side of anything and there isn't much that can fall off beside the tiles. This would require a tile falling off and then either onto the leading edge of the wing things, or back into the hull. However if the tiles are more secure than the shuttles, then this is less of an issue than on the shuttle.

Assuming, of course, that they don't change the heat shield design again.

[kerbiloid]

8 hours ago, StrandedonEarth said:

I think the biggest problem with D2 propulsive landing is the toxic hypergolics contaminating the landing area.

Afair, the main problem was with its heatshield and legs.
As the heatshield is not jettisonable, the legs cannot be foldable, only telescopic and vertical.

So, in case of hard landing the legs will be pushed up and pierce either fuel tanks or crew cabin, so their safety is insufficient.

As its inner engines are also used as a LES, so in case of launch abort it has to either splash or hard-land on the backup chute.

As they can't make the heatshield jettisonable, they can't change the legs.

So, the legs are considered unsafe, and no legs - no propulsive landing (as the capsule is designed to land on legs, not on heatshield).

So, as the legs are no go, and the crewed propulsive landing is not a thing anymore, they have to splash it into the horrible corrosive seawater, and the capsule anyway becomes unhuman-rated.

As the capsule becomes single-crewed-use, the whole idea of internal LES becomes reveals to be pointless, as the capsule anyway costs more than a powder rocket on top, so instead of a cheap single-use powder rocket they get 8 single-use superdracos.

So, the Crew Dragon just lost its sense as a crewship (especially after CST-100 maiden flight _{which I was believing in, rather than in Crew Dragon}).
Though, they still could use it as a test platform of propulsively landing cargo ship to bring back wastes instead of dumping them into the atmosphere, like others do.

Conclusion 1: dragons are Targaryen-only (no matter, Dragon, Draco, or Superdraco). Also maybe for Malfoys.
Conclusion 2. Merlin is greater than dragons. In space, too.

Recommendation: rename the Starship into Pendragon. It's like dragon, but also from Merlin's team.
Maybe even into Uther Pendragon where Pendragon is the 1st stage, while Uther - the orbital ship.

Edited January 1, 2020 by kerbiloid

[Guest]

I hope they get the next Starship flight ready soon... So cruel building an awesome looking spaceship to get us all excited and then taking it away  

[tater]

 

[tater]

 

[Technical Ben]

On 12/31/2019 at 3:27 PM, tater said:

The point of Starship is to be cheaper to operate than any flavor of Falcon 9. At that point, it doesn't matter that any F9 type (Dragon, fairing, whatever) is smaller. Only cheaper matters---or for crew, safety. I can see a long time where F9 stays around as a crew vehicle (with Crew Dragon) since it's human rated, until anyone feels comfortable riding on Starship.

It matters if I want to use Falcon 9s as my "shuttles" for planetary landings (disposable/reuse stages) for my Sci-fi. Elon is doing me no favours if I cannot predict the results... my sci-fi will all be wrong if I they go and build different craft after all this. XD

I estimated shuttle designs (skylon) and small rockets (falcon 9 style). Now he's gone and done a massive thing (witch would be single stage to orbit on anything Mars or smaller, and in my Sci-fi, I'd not expect any earth like planets to be worth it, as terraforming would take thousands of years, so the smaller planets become more desirable for smaller gravity wells).

17 hours ago, Ultimate Steve said:

Also this isn't directly what the question asked but there is far less chance of something breaking off and hitting the heat shield on starship than on the shuttle. Starship isn't on the side of anything and there isn't much that can fall off beside the tiles. This would require a tile falling off and then either onto the leading edge of the wing things, or back into the hull. However if the tiles are more secure than the shuttles, then this is less of an issue than on the shuttle.

Assuming, of course, that they don't change the heat shield design again.

Also, with multiple and quick turnarounds, they could launch a second, and transfer crew. The only reason this was not done for the shuttle was timescales and prohibitive costs. If costs and timescales come down, any faults are eaten up in the profit margin (and SpaceX survives or goes bankrupt on it), where as for "all or nothing" scientific expeditions, risks are kinda different.

[Motokid600]

On 12/31/2019 at 6:17 PM, RealKerbal3x said:

The heat shield is curved. That could lead to the capsule tipping after landing and being damaged.

Nah. It'd settle to one side. The landings are much, much softer then parachute. Could even make a cradle to land in.