No, I just think this is Elon, for whatever reason, putting full
reusability off into the FAR future, because he can't realistically do it;
at least right now, and possibly ever. The only question in my mind is how
long he knew that he couldn't do it. Perhaps nobody dared tell him, he has
some reputation for firing good people for "rational" reasons, or perhaps
he had some business reasons for spinning what is pretty much vaporware in
2011. I mean first stage reuse, sure, but full reuse??? You'd have to get
the 2nd stage down from orbital speed, it needs significant reentry
equipment, which is normally very heavy. It's quite like trying to reuse
the external tanks with the Space Shuttle. It's a whole bunch of hard, and
probably expensive research; which NASA never cracked, and it's not a
question of whether you lose payload, it's a question of how much. You
would think he would have had computer models that told him it wasn't going
to happen.
Nevertheless, his expendable rockets seem really good, but it makes him
look bad to say he would do something and then roll it back. Lots and lots
of people still think he's going to do full reuse with Falcon 9, or
presumably even Falcon Heavy, but he's stated he won't do it with the
Falcon 9 core.
On 24 December 2015 at 23:53, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
wrote:
More like 3% better, IIRC.
On 12/24/2015 11:46 AM, George Herbert wrote:
Should see ~10% better Isp from methane compared to kero?...
George William Herbert
Sent from my iPhone
On Dec 24, 2015, at 8:15 AM, Ian Woollard <ian.woollard@xxxxxxxxx
<mailto:ian.woollard@xxxxxxxxx>> wrote:
This subcooled methane idea, how is it supposed to work?
I thought about it, and pulled some of the physical data, but I'm
still not quite getting it.
Presumably you cool it down so that the vapour pressure is low, so the
tank walls can be thin and light and I ran cpropep-web and looks like
you'll get nearly the same Isp as Kerosene. But the propellant density
and impulse density is unimpressive.
I can see some small wins, like you it helps having the two
propellants at about the same temperature, but no big win. What am I
missing?
To be honest, Musk really needs a hydrogen upper stage.
And Musk's other idea of making everything bigger, it would help a
bit; but Falcon 9 is pretty big already; he'd mainly gain on the
reduced reentry shielding due to area/volume relationships.
On 24 December 2015 at 14:42, Findley, Jeff <jeff.findley@xxxxxxxxxxx
<mailto:jeff.findley@xxxxxxxxxxx>> wrote:
On Wednesday, December 23, 2015 3:09 PM Derek Lyons wrote:____
> Quoted for truth. "Everyone" expected him to stick the first
barge landing. And the second. And the third.____
> Yet the times he didn't and their predictions were wrong have
already gone down the memory hole.____
__ __
We’re skirting very close to “fanboy bashing”, which I’ve seen on
enough websites over the years. “The other side” has called
Musk’s Falcon 9 a “hobby rocket”, criticized the “low performance”
of the Merlin engines, and said that reuse would never happen
(because smarter minds than his have not been able to do it yet,
so it must not be possible). So, all of those predictions have
also “gone down the memory hole”.____
__ __
> As Bill correctly points out, there's good reason for healthy
skepticism. (Not the least of which is the track ____
> record of a very complicated and "sporty" landing sequence.)____
__ __
While true, Musk also has a mind for the future. Let’s draw some
parallels with Tesla...
The first Tesla was an extremely impractical car, but you have to
start somewhere (Falcon 1). The second Tesla was a quite
impressive car, but still far too expensive for most people to
afford at about $100k (Falcon 9 and Falcon Heavy). Eventually,
Musk plans on selling an “affordable” car, but it requires
building the biggest battery factory on the planet before he can
even think about starting production (LOX/methane fully reusable
launch vehicle).____
__ __
Say what you will about Musk, but he thinks big, and he thinks
very long term. ____
__ __
Jeff____
__ __
--____
Jeffrey Findley____
Product Eng____
__ __
Siemens Industry Sector____
Siemens Product Lifecycle Management Software Inc.____
2000 Eastman Drive____
Milford, OH 45150 United States ____
Tel. :+1 (513) 576-5606 <tel:%2B1%20%28513%29%20576-5606>____
Fax :+1 (513) 576-2840 <tel:%2B1%20%28513%29%20576-2840>____
jeff.findley@xxxxxxxxxxx <http://jeff.findley@xxxxxxxxxxx%20>____
www.siemens.com/plm <http://www.siemens.com/plm>____
__ __
*From:*arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>] *On Behalf Of *Derek Lyons
*Sent:* Wednesday, December 23, 2015 3:09 PM
*To:* arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
*Subject:* [AR] Re: Re spacex falcon 9 landing____
__ __
On Dec 23, 2015 11:44 AM, "William Claybaugh"
<wclaybaugh2@xxxxxxxxx <mailto:wclaybaugh2@xxxxxxxxx>> wrote:____
> Take care; there is a difference between doubt and >professional
caution: I'm inclined to the view that >competent engineers, given
good specs, will at least >meet their goals. Thus it seems likely
that Falcon 9 will >be easier to refurbish than previous examples
>of reusable hardware. But in addition to being designed >for
reuse it was also designed for very low cost as an >expendable.
It is worth considering whether the total >cost of reuse is going
to be lower than the intentional-->and demonstrated--low cost of
expending. That is not >doubt, that is a subject matter expert
thinking carefully >bout the the details.
>
> Just sayin'
>
> Bill____
Quoted for truth. "Everyone" expected him to stick the first
barge landing. And the second. And the third. Yet the times he
didn't and their predictions were wrong have already gone down the
memory hole.____
As Bill correctly points out, there's good reason for healthy
skepticism. (Not the least of which is the track record of a very
complicated and "sporty" landing sequence.)____
D.____
--
-Ian Woollard
Sent from my Turing machine