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Second stage reusability has been on and off again and is now on again. However SpaceX seem to have put very little effort into it so far. If we read between the lines of what Elon has tweeted then they will probably start to put significant effort in later this year.
They put quite a bit of effort into it 2011-2014. Then Musk announced at an MIT media event it was off the table for all hardware based on the F9 architecture.

Quote from: MikeAtkinson
Well it is over 80% of a RLV by value of manufactured components. Cost of launch also includes range, payload integration, insurance and other such costs as well as the manufacturing costs.
Which is a perfect argument for not pursuing US reuse, isn't it?
Quote from: MikeAtkinson
It seems that SpaceX plan about 60 launches per year, half of which will be for Starlink which are not performance constrained and many of the rest having excess performance (just about anything to LEO including Dragon). Having a large remaining payload  is not going to be a problem for LEO launches.
I wish SX every success in this latest attempt, but it's not really relevant to the thread title.
Quote from: MikeAtkinson
Of course there is no guarantee they can make US recovery work (that is statement about the future and many things could change), however it is likely that they can make US recovery work (because of their track record, also because they will have plenty of opportunities to iterate over the next few years).
You're a bit behind the curve.  That was the view in 2011, before they gave up the last time.  :(
This is not the place to re-hash the physics or the materials science (look in the relevant SX US reusability threads. Roughly speaking it's 20x harder than booster recovery. Run the numbers). Neither has changed radically enough to change the outcome.
The only thing that might have changed enough is SX's understanding.

This is not engineering. It's science, and that is massively unpredictable.

It's the difference between the steady improvement in Lithium batteries (fairly predictable) and the date the first commercial fusion power plant will start operating.
Again. Not really relevant to this thread.
Quote from: MikeAtkinson
A cost of $500 M over the next three years would imply about 1000 engineers working on US reusability, which seems high. It won't be more than about 3 years as they will either succeed or give up because at some point there would not be time to recover  future expected expenses over the expected remaining F9/FH launches. Elon Musk does not seem to fall for the sunk cost fallacy, so it will only be costs going forward that will affect that decision (those costs will include opportunity costs).
At c $1666m/year that's more like 670 staff, but it's still a very substantial effort.
Again, not really sure this is relevant to the thread title.
You have to understand the numbers he says in their context. The 100 passangers came from the following trail of thought:

I would like to suggest an alternative theory:
*Going bigger then 9 meters in diameter would be very expensive to develop and use
*A 9 meter vehicle could fit 825 cubic meters of pressurized volume while still being aerodynamically stable
*8 meters per person is luxury
*BFR fits 100 people

The 9m is the result (in my opinion) of the desire to use 39A as a launch pad. For larger diameters, you would have larger liftoff thrust. 39A is at its limit with the current design. Building a new pad at the cape is a very large problem for current SpaceX (maybe that may change in 10 years). To replace F9, they have to launch from the cape, so there is that limitation. They have the launch pad development at Boca Chica, but the launch trajectories are very limited from there. They cant reach all orbits they need, hence the requirement to launch from the cape. I dont know what that will do for polar orbits though. Maybe dogleg from the Cape so that they dont need BFR at Vandenberg.
Commercial Space Flight General / Re: XCOR and the Lynx rocket
« Last post by john smith 19 on Today at 06:59 AM »
I don't know if anyone would find this interesting, but here is one of the few (maybe only?) public videos of the 5H25 hydrogen engine firing. It showed up briefly on the XCOR youtube channel before being taken down, but it was copied and uploaded by someone else before it was pulled.

Very clean burn. Expected more heat shimmer.
Is that Doug Jones on the audio?
I guess this is new...

"I don’t want to say too much. We’re building up the test stand right now. We’ve got the first flight version of that engine in work. We’ve been running the development engine quite a bit. It’s running great," Mueller told the audience.

From GeekWire
Yes, the story has certainly crossed a threshold or inflection point with the new situation.

What is the meaning or significance of that final scene?
Report of the talk with some extra quotes not on this thread:

SpaceX propulsion guru Tom Mueller looks ahead to Raptor rocket engines for Mars

BY ALAN BOYLE on May 24, 2018 at 8:56 pm

LOS ANGELES — SpaceX’s success owes a lot to the tenacity of the company’s billionaire founder, Elon Musk, but some of the credit has to go to the guy who designed the engines that make the rockets go.

On Raptor:

“I don’t want to say too much. We’re building up the test stand right now. We’ve got the first flight version of that engine in work. We’ve been running the development engine quite a bit. It’s running great,”
A former co-worker of mine went to work on Galileo over 20 years ago. Even if a UK alternative were given high priority it would take over 10 years to get an operational system. Adding in Australia and Japan would only lengthen the process, and such cost shares sometimes end up costing the major participant more money in the long term.

I would put sat-nav below all other satellite systems in priority, number one is probably enhanced skynet, then sig int, optical, sar, and general earth observation. Any scenario where the UK does not have access GPS and/or Galileo would also mean it did not have access to ISR assets, but it is easy to imagine cases where satellite intelligence was not shared.

So would you say the UK government is over prioritising satellite navigation then?
Suborbital Missions / Re: The suborbital thread!
« Last post by Lewis007 on Today at 06:20 AM »
An unarmed Minuteman III intercontinental ballistic missile (GT-224GM) was launched from LF-04 at Vandenberg AFB at 01:23 PDT on May 14.
More info:

Attached: video
goes here in its dedicated thread:

I saw the thread, but because of its title, I placed it in the suborbital launches thread.
The VAFB thread should be called VAFB suborbital launches or something like that, not VAFB missile test notices.
Personally, I prefer to have all these launches in one suborbital thread. It's confusing that some suborbital launches have their own thread, and all others go in the main thread. If a split is made, I believe one distinguishing between missile tests and science/technological missions makes more sense.
, but the key was that the Ariane program was simply a lower cost, more efficient effort than STS, Atlas Centaur, Titan 3 Commercial, etc..

Yes and no. The shuttle was flawed, but Delta, Atlas-Centaur and Titan III-B each could have buried Ariane in infancy.
The real crime was to retire all those ELVs.

Mind you, the very Frederic d'Allest, boss of the CNES in 1977, recognized many years later "Against Atlas-Centaur, Ariane was toast. Fortunately enough, they retired it for the Shuttle."

 Case in point: Atlas-Centaur had INTELSAT V launch contracts, and INTELSAT was perfectly satisfied, so INTELSAT VI should not have been different. Yet Ariane got its breakthrough.

The amazing thing is that both Ariane and Airbus were dying by 1977, and then only weeks apart, Eastern Airlines (Frank Borman !!!) and Intelsat saved their a**es and gave the breakthrough they needed.

Yessir, what you describe is exactly what happened. Ariane got to be so successful due to plain stupidity on the part of the USA. The USA forcing all ELV launches to fly on STS was a disaster in the making. When Challenger happened the USA decided to reverse course. But the damage had already been done. Arianespace had, in the short space of just 9 years, gained a nearly 50% market share. The EELVs entered the market in the early 1990s and by then Ariane was well over 50% market share and as reliable as a launcher can be. That situation is only now changing (courtesy of SpaceX). Imagine that: a single disastrous US policy decision crippled the US commercial launch market for 4 almost decades.
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