I very much enjoyed the landing; any time anyone manages to land a rocket
vertically, that's a very tough thing to do.
Anyway, I decided to take stock of what Elon Musk initially said he would
do with regards reuse, and what has been done, and what has subsequently
been said they will not do.
There was this video:
https://www.youtube.com/watch?v=sSF81yjVbJE
a very well done, aspirational video showing a Falcon9 looking rocket
making costs cheaper by reusing all of its parts.
However, at the time, this video bothered me. I couldn't understand how it
could really work, vehicle and trajectory modelling I had privately done
seemed to make this incredibly hard; the vehicle seemed to lose performance
from the recovery equipment and landing delta-v and the trajectories you
had to follow; I personally was unable to get all those worms into the box
at the same time in any convincing way, and yet, Elon was announcing it!
However, eventually I saw this video with an interview with Elon in 2014, 3
years later: I didn't initially get it, but Wikipedia pointed it out more
clearly, and then it all made sense:
https://www.youtube.com/watch?v=y13jbl7ASxY&feature=youtu.be&t=14m20s
So that initial video was very over optimistic, and my modelling and
analysis seem to have been basically correct.
So there's to be a reusable first stage and a reusable capsule, but there's
not going to be a reusable second "upper" stage; unless they get
LOX/methane to work closed cycle on later rockets maybe. I've never
modelled LOX/methane so I don't know whether that would give enough of a
performance boost; and based on Musk's record of overpromising, and the
difficulties, I wouldn't exactly bet my life savings on that either.
Anyway, the reusability they are going for right now is cool beans, but
it's not quite as earth shattering as we could hope for.
On 23 December 2015 at 01:07, John Dom <johndom@xxxxxxxxx> wrote:
The return plot on the booster profile graph is amazing. Flew back
(translated) 95 km from 180 km altitude like a helicopter J. Starting at
Mach 5 or so. Amazing.
Why are there 2 velocity maxima I wondered.
It looks like the landing spot was about 8 km from the launch pad on the
profile graph.
JD
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *David McMillan
*Sent:* dinsdag 22 december 2015 18:42
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: SpaceX F9 Launch/Update -- Live Link
Well, like they say, the best way to get a correct answer on the
internet... :)
On 12/22/2015 12:27 PM, Lars Osborne wrote:
David,
I was told by one of my coworkers that the simulation you posted is old.
This one is supposed to be more accurate (and way more detailed):
http://www.flightclub.io/results.php?id=0490d68b-62a1-4a2a-b39a-f47bacadc6e3&code=OG22
Thanks,
Lars Osborne
On Tue, Dec 22, 2015 at 9:11 AM, David McMillan <skyefire@xxxxxxxxxxxx>
wrote:
On 12/22/2015 12:04 PM, John Dom wrote:
As to the successful F9 v1.01 stage 1 return yesterday, again I’d love to
see the 3D graph (km scale) of the booster *return* trajectory. The gravity
turn to orbit as shown on ascent footage must have sent it far down from
the pad. How high did it fly? Range at separation?
Not entirely sure of the provenance, but here's one (2D) I came across.