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SpaceX Launches, Landings and News

Apparently, in a month they'll reveal engineering modifications to the BFR based off of results from testing components.
 
Twisted Mentat said:
But remember the Shuttle was reusable too. It just required what amounted to a rebuild every time. From memory SpaceX haven't said just how much they had to replace/rebuild for this launch.
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We now have a figure for this! Shotwell talked at the 33rd space symposium yesterday, and she mentioned that the refurb cost was substantially less than half the cost of a new stage despite doing substantially more work on it than they'll do in the future.
 
RRoan said:
We now have a figure for this! Shotwell talked at the 33rd space symposium yesterday, and she mentioned that the refurb cost was substantially less than half the cost of a new stage despite doing substantially more work on it than they'll do in the future.
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Awesome!

Now, to guess what "substantially less than half" means!

I'm thinking somewhere in the ballpark of 35%. Lower than that, and you'd start saying things like "a third" or "a quarter" or a "fifth." If they put, say, twice the effort into refurb this time around, normally refurb would probably end up costing 18% or so. I'm guessing repairing/replacing the grid fins would be a substantial part of the remaining cost, and when they switch to titanium later this year, that could drop it to 12% or so. Assuming lots of little tune-ups, Block 5 might be able to drop that down to 8%. Granted, this is blatant speculation, but it strikes me as fairly reasonable, all things considered. That it's even conceivable that by the end of the year we could have orbital boosters with single-digit refurb costs is crazy.
 
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So Elon made an interesting tweet today:

For something like two years SpaceX said reusing the upper stage wasn't possible. Then since the SES-10 launch they've gone from that to "we might try recovering it" and now "recovery by end of next year".

One of the issues with reusing the upper stage is that every kilogram spent on the reuse system is one lost from the payload. However something people on /r/SpaceX have brought up is that the heaviest GTO stats clock in at ~6t and the Falcon Heavy has ~8t to GTO. That leaves ~2t for reuse equipment and if it works out a 100% reusable Falcon Heavy could quite conceivably be cheaper then a mostly reusable Falcon 9.
 
UberJJK said:
So Elon made an interesting tweet today:

For something like two years SpaceX said reusing the upper stage wasn't possible. Then since the SES-10 launch they've gone from that to "we might try recovering it" and now "recovery by end of next year".

One of the issues with reusing the upper stage is that every kilogram spent on the reuse system is one lost from the payload. However something people on /r/SpaceX have brought up is that the heaviest GTO stats clock in at ~6t and the Falcon Heavy has ~8t to GTO. That leaves ~2t for reuse equipment and if it works out a 100% reusable Falcon Heavy could quite conceivably be cheaper then a mostly reusable Falcon 9.
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Can you actually get landing equipment and a heatshield for a second stage under 2 mT? Also, if we go by the old video they released a while back (below), it looks like the return system will be an entirely second set of engines, and that's not even accounting for the fact that you have to do something with the oversized vacuum-rated nozzle. Granted, nozzle extensions are an existing thing, but that's still more mass and more complexity, and while it's probably trivial, has anyone ever made one that can collapse after extending?

 
Volt Cruelerz said:
Can you actually get landing equipment and a heatshield for a second stage under 2 mT?
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That is the question. Given how Elon Musk suddenly seems rather optimistic about the idea I'm guessing they've figured out a way of doing it.

Volt Cruelerz said:
Also, if we go by the old video they released a while back (below)
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As I understand it that video isn't very accurate at all. It was done in the early days of SpaceX and there wasn't very good communication between SpaceX and the animation company behind it.
 
UberJJK said:
However something people on /r/SpaceX have brought up is that the heaviest GTO stats clock in at ~6t and the Falcon Heavy has ~8t to GTO. That leaves ~2t for reuse equipment and if it works out a 100% reusable Falcon Heavy could quite conceivably be cheaper then a mostly reusable Falcon 9.
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The GTO payload listed on the SpaceX site for FH was actually increased ~20% at some point in the last couple of weeks. That's expendable, but if it carries over to a fully reusable flight then we're looking at a reuse mass budget of 3-3.5 tons. That means they could pretty much double the current dry mass of the stage.

Volt Cruelerz said:
Can you actually get landing equipment and a heatshield for a second stage under 2 mT? Also, if we go by the old video they released a while back (below), it looks like the return system will be an entirely second set of engines, and that's not even accounting for the fact that you have to do something with the oversized vacuum-rated nozzle. Granted, nozzle extensions are an existing thing, but that's still more mass and more complexity, and while it's probably trivial, has anyone ever made one that can collapse after extending?

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Heatshield shouldn't be a problem. PICA is incredibly lightweight and hardly ablates at all. One metric ton would get you a layer ~5cm thick over the entire stage, and you really only need a lot on one side. Obvious answer for landing engines is a set of Superdracos, and two would give you more than enough thrust for a landing. Too lazy to estimate the amount of mass for hypergolic fuel and tanks, but I can't imagine it'd be prohibitive.

As for the Merlin... obvious thing to do is to have the heatshield extend down to protect it like on the ITS. You could even have it double as an aerodynamic surface like the STS body flap. The vacuum nozzle might be too large to make that light enough, though. If that's the case I'd consider just dumping the nozzle extension rather than trying to make it extend and retract. Everything under the gas generator exhaust is thin sheet metal, so they should be able to make it pretty cheaply.
 
Why not just have the second stage pop a parachute or three and soft-land in the water near the barge, or on a giant airbag on the barge?

I mean, we're talking about secondary motor and fuel systems and such, which is a lot of weight. Why not KISS it?
 
RocketMedic said:
Why not just have the second stage pop a parachute or three and soft-land in the water near the barge, or on a giant airbag on the barge?

I mean, we're talking about secondary motor and fuel systems and such, which is a lot of weight. Why not KISS it?
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1. Parachutes stress your structure in a different direction than propulsive landing, so building your frame to handle that can add a lot of complexity and weight.
2. Fishing something out of the ocean is certainly possible, but the electronics will be ruined as will a lot of other things.
 
RocketMedic said:
Why not just have the second stage pop a parachute or three and soft-land in the water near the barge, or on a giant airbag on the barge?
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Well first off landing in the water is basically pointless for reuse. Salt water is nasty and the whole stage would basically have to be replaced anyway. Just look at the Space Shuttle's SRBs. Sure they were "recovered" but if you dig into it you'll find they were completely disassembled and only a handful of parts were reused.

Landing on the barge almost certainly wouldn't work because the upper stage has a dry mass of ~4t which means not only are you never going to hit the barge but even if you do the stage will be going too fast and crunch on impact. Giant airbags have the same accuracy problems but trade crunching the first stage for potentially popping the airbag. Airbags work, or at least are planned to work, for fairing recovery because the fairings are a quarter the mass.
 
RocketMedic said:
Why not just have the second stage pop a parachute or three and soft-land in the water near the barge, or on a giant airbag on the barge?

I mean, we're talking about secondary motor and fuel systems and such, which is a lot of weight. Why not KISS it?
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Parachutes are heavy and awkward to work with. It might well be cheaper, lighter, and easier to use rockets.
 
RocketMedic said:
Why not just have the second stage pop a parachute or three and soft-land in the water near the barge, or on a giant airbag on the barge?

I mean, we're talking about secondary motor and fuel systems and such, which is a lot of weight. Why not KISS it?
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The trouble with parachutes is they tend to land wherever the wind wills it. This makes landing on dry ground fraught with difficulty in that unless you are aiming for a giant grassland, it's going to be full of lumpy things that don't make for soft landings. Or you land in water, which makes reuse and refurbishment a nightmare.

Either way parachutes make rapid cost effective recovery and reuse very difficult as they need to land far away from civilization to avoid risk, and that makes recovery rather difficult, especially when you are talking about a fragile thing that weighs several tons and is the size of a city bus.

Vertical powered landing lets you park it on a landing pad within transporter truck distance of your hanger, or on a ship that can sail it back into your spaceports local ocean port. Parachute landing on land or sea means having to get a heavy lift helicopter or truck out to it, or a special crane equipped ship with divers.
 
Well, this has been a nice weekend. Third relaunched rocket, first successful three-engine landing, first geo-transfer recovery I can recall, and they tested the new titanium grid-fins.

And they just launched two in less than 48 hours (though just barely). Goddamnit, they're making this look easy!
 
RRoan said:
The GTO payload listed on the SpaceX site for FH was actually increased ~20% at some point in the last couple of weeks. That's expendable, but if it carries over to a fully reusable flight then we're looking at a reuse mass budget of 3-3.5 tons. That means they could pretty much double the current dry mass of the stage.



Heatshield shouldn't be a problem. PICA is incredibly lightweight and hardly ablates at all. One metric ton would get you a layer ~5cm thick over the entire stage, and you really only need a lot on one side. Obvious answer for landing engines is a set of Superdracos, and two would give you more than enough thrust for a landing. Too lazy to estimate the amount of mass for hypergolic fuel and tanks, but I can't imagine it'd be prohibitive.

As for the Merlin... obvious thing to do is to have the heatshield extend down to protect it like on the ITS. You could even have it double as an aerodynamic surface like the STS body flap. The vacuum nozzle might be too large to make that light enough, though. If that's the case I'd consider just dumping the nozzle extension rather than trying to make it extend and retract. Everything under the gas generator exhaust is thin sheet metal, so they should be able to make it pretty cheaply.
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The hard part isn't the mass of the heat shield or even the landing. It simply that the the heat shield has to be up front and a hilariously huge percentage of the mass of a almost empty stage is in the rear. It is like trying to get a shuttle cock to fly tail end first. There are ways to counteract that but all of them hit the mass budget more than the heat shield or the propellant for landing. The falcon heavy might have enough spare mass to have a reusable second stage for LEO launches that aren't to large but I very much doubt the falcon 9 will ever fly a reusable second stage.
 
Due to the satellite being heavy (6 tons) and going to geostationary orbit, this will be an expendable launch with no recovery attempt. Live stream will be here:



This will be SpaceX's fourth launch in 30 days.
 
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