SpaceX Tuesday...
Discussion
I sneakily managed to watch the launch and its reappearance on the ship. Glad to hear the satellites were deployed OK and are all talking to their ground control.
A dramatic open shutter view of today's launch, separation and boostback burn.
A dramatic open shutter view of today's launch, separation and boostback burn.
Edited by Beati Dogu on Monday 9th October 20:07
Toaster said:
Shouldn't this now be on the travel thread, these flights as pointed out are routine. I can't see any Science being discussed.............its only a question don't flame me........
1) They're doing very well, but not quite up to airline standards yet.2) Falcon heavy, Dragon 2 and ultimately BFR/BFS are still, perhaps arguably, "science".
3) No-one really cares what you think.
Einion Yrth said:
1) They're doing very well, but not quite up to airline standards yet.
2) Falcon heavy, Dragon 2 and ultimately BFR/BFS are still, perhaps arguably, "science".
3) No-one really cares what you think.
No one cares what I think........clearly thats not true, but it would be good to see science being discussed rather than a launch schedule 2) Falcon heavy, Dragon 2 and ultimately BFR/BFS are still, perhaps arguably, "science".
3) No-one really cares what you think.
Musk AMA recently on reddit..
https://www.reddit.com/r/space/comments/76e79c/i_a...
He didn't appear to answer too many questions, so I copied over the ones I found most interesting...
Q: Why was Raptor thrust reduced from ~300 tons-force to ~170 tons-force?
EM: We chickened out. The engine thrust dropped roughly in proportion to the vehicle mass reduction from the first IAC talk. In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.
Q: Will the BFS tanker's payload section be empty, or include extra propellant tanks?
EM: At first, the tanker will just be a ship with no payload. Down the road, we will build a dedicated tanker that will have an extremely high full to empty mass ratio (warning: it will look kinda weird).
Q: With the first two cargo missions scheduled to land on Mars in 2022, what kind of development progress can we expect to see from SpaceX in the next 5 or so years leading up to the maiden flight?
Will we see BFS hops or smaller test vehicles similar to Grasshopper/F9R-Dev? Facilities being built? Propellant plant testing? etc. etc.
EM: A lot. Yes, yes and yes.
Will be starting with a full-scale Ship doing short hops of a few hundred kilometers altitude and lateral distance. Those are fairly easy on the vehicle, as no heat shield is needed, we can have a large amount of reserve propellant and don't need the high area ratio, deep space Raptor engines.
Next step will be doing orbital velocity Ship flights, which will need all of the above. Worth noting that BFS is capable of reaching orbit by itself with low payload, but having the BF Booster increases payload by more than an order of magnitude. Earth is the wrong planet for single stage to orbit. No problemo on Mars.
Q: The sub-scale Raptor prototype has a (speculated) thrust of about ~100 tons-force currently, and will be scaled up to ~170 tons-force according to your IAC/2017 design
Can you tell us more about the current status and expected (best-case) timeline of this scale-up effort?
EM: Thrust scaling is the easy part. Very simple to scale the dev Raptor to 170 tons.
The flight engine design is much lighter and tighter, and is extremely focused on reliability. The objective is to meet or exceed passenger airline levels of safety. If our engine is even close to a jet engine in reliability, has a flak shield to protect against a rapid unscheduled disassembly and we have more engines than the typical two of most airliners, then exceeding airline safety should be possible.
That will be especially important for point to point journeys on Earth. The advantage of getting somewhere in 30 mins by rocket instead of 15 hours by plane will be negatively affected if "but also, you might die" is on the ticket.
Q:Will the BFS tanker ships (have to) do a hoverslam landing?
EM: Landing will not be a hoverslam, depending on what you mean by the "slam" part. Thrust to weight of 1.3 will feel quite gentle. The tanker will only feel the 0.3 part, as gravity cancels out the 1. Launch is also around 1.3 T/W, so it will look pretty much like a launch in reverse....
https://www.reddit.com/r/space/comments/76e79c/i_a...
He didn't appear to answer too many questions, so I copied over the ones I found most interesting...
Q: Why was Raptor thrust reduced from ~300 tons-force to ~170 tons-force?
EM: We chickened out. The engine thrust dropped roughly in proportion to the vehicle mass reduction from the first IAC talk. In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.
Q: Will the BFS tanker's payload section be empty, or include extra propellant tanks?
EM: At first, the tanker will just be a ship with no payload. Down the road, we will build a dedicated tanker that will have an extremely high full to empty mass ratio (warning: it will look kinda weird).
Q: With the first two cargo missions scheduled to land on Mars in 2022, what kind of development progress can we expect to see from SpaceX in the next 5 or so years leading up to the maiden flight?
Will we see BFS hops or smaller test vehicles similar to Grasshopper/F9R-Dev? Facilities being built? Propellant plant testing? etc. etc.
EM: A lot. Yes, yes and yes.
Will be starting with a full-scale Ship doing short hops of a few hundred kilometers altitude and lateral distance. Those are fairly easy on the vehicle, as no heat shield is needed, we can have a large amount of reserve propellant and don't need the high area ratio, deep space Raptor engines.
Next step will be doing orbital velocity Ship flights, which will need all of the above. Worth noting that BFS is capable of reaching orbit by itself with low payload, but having the BF Booster increases payload by more than an order of magnitude. Earth is the wrong planet for single stage to orbit. No problemo on Mars.
Q: The sub-scale Raptor prototype has a (speculated) thrust of about ~100 tons-force currently, and will be scaled up to ~170 tons-force according to your IAC/2017 design
Can you tell us more about the current status and expected (best-case) timeline of this scale-up effort?
EM: Thrust scaling is the easy part. Very simple to scale the dev Raptor to 170 tons.
The flight engine design is much lighter and tighter, and is extremely focused on reliability. The objective is to meet or exceed passenger airline levels of safety. If our engine is even close to a jet engine in reliability, has a flak shield to protect against a rapid unscheduled disassembly and we have more engines than the typical two of most airliners, then exceeding airline safety should be possible.
That will be especially important for point to point journeys on Earth. The advantage of getting somewhere in 30 mins by rocket instead of 15 hours by plane will be negatively affected if "but also, you might die" is on the ticket.
Q:Will the BFS tanker ships (have to) do a hoverslam landing?
EM: Landing will not be a hoverslam, depending on what you mean by the "slam" part. Thrust to weight of 1.3 will feel quite gentle. The tanker will only feel the 0.3 part, as gravity cancels out the 1. Launch is also around 1.3 T/W, so it will look pretty much like a launch in reverse....
More news on the new 'Zuma' Falcon 9 launch. The next launch from Vandenberg has also been given permission for an RTLS landing
https://www.nasaspaceflight.com/2017/10/spacex-zum...
https://www.nasaspaceflight.com/2017/10/spacex-zum...
Gassing Station | Science! | Top of Page | What's New | My Stuff