JF Mezei wrote on Sun, 20 May 2018
18:21:36 -0400:

On 2018-05-20 16:58, Fred J. McCall wrote:

They've only launched half a dozen of them, for Christ's sake! The
fourth launch failed catastrophically and led to a temporary stand
down of some duration. To use it for commercial launches someone
would need to contract with them for a commercial launch. It's early
days...

Considering they are in production for ISS cargo launches, I would have
expected them to seek out comemrcial launches and be in the news for
winning such contracts.


Consider they just returned to operation in 2016 with a new
configuration and new engines, I would expect commercial customers to
be a little leery.


Or does the Virginia/Maryland launch latitude result in sufficient cargo
penalty for GTO that they can't compete?


Antares capability to GTO would be miniscule and they've never
launched a GTO payload.


You know, this stuff is not hard to find out. I looked for less than
five minutes. Look into Prometheus, Adeline and Ariane 6.

I checked Wikipedia entry for ESA and didn't find any text on future
launchers. Would have expected this to be in that one.


So your expectation is to be spoon fed? I've certainly noticed that.
Again, less than five minutes...


You mean ULA, which is the space business spun off by Boeing and
Lockheed. The only thing they'll have that SpaceX doesn't is that
they're not SpaceX.

I cases where a payload and orbital inclination means SpaceX can't land
the booster, woudln't ULA become on a less unequal footing than SpaceX ?


Less unequal, but still more expensive by a lot.


In cases where Boeing makes the staellite and uses ULA, could this
become more competitively priced (a "bundle") as opposed to Boeing
making satellite and using SpaceX to launch?


No.


I realise ULA will be more expensive than SpaceX but if there are
situations where the price difference in no longer orders of magnitutes,
then perhaps ULA still has some market niche.


The price difference is never "orders of magnitude". Do you even know
what that means?


Depends on the engine type. It certainly takes some additional
hardware and a lot of testing.

Isn't restart a no brainer?


See above.


Non-Hypergolic stage 2s all have ability to
start in vacuum and that seems to be a pretty reliable technology.


Not true.


Since rocket engines are fired multiple times for tests prior to going
in a rocket, ...


Not a given.


... is "restart" the issue as opposed to self-contained ignition?


The latter is required for the former.


And where does ignition happen? at the narrower part fo engine bell? or
inside the combustion chamber?


It's called a 'combustion chamber' for a reason...


in other words: does ignition happen in a place where outside conditions
are not important (falling backwards in atmosphere, staic on pad, or in
vacuum) ?


A usual, those are indeed 'other words' and they have no connection to
the original word. There is no such place "where outside conditions
are not important".


Did the shuttle have the equivalent of a spark plug inside the engine,
but powered by the ground, or did the pad have some prod that went up
each of the 3 engine bells with the spark plug at the end ?


I don't believe Shuttle engines were ever restarted after MECO.


Or were engines ignited by the sparks seen on launch videos way below
the bells (which comentators explained existed to burn off any stray
hydrogen before ignition).


Oh, good Lord!


See the list of stuff changed for Falcon 9 Block 5.

Block 4 landed sucesfully. 5 made it easier to re-use, it didn't add
the ability to land sicne it was already there.


Don't ask questions if you don't want the answers.


Most rockets
don't try to land. Why do you think that is?

Because people, having no choice but to pay the big bucks to ULA meant
ULA had no motivation to change their rockets. Now that SpaceX has done
it and is offering significantlty lower launch costs, my curiosity is
just how difficult it is at the hardware level to add landing capability.


Do you see ULA landing rockets now? No. Do you see ESA landing
rockets now? No. Do you see ANY launch providers other than SpaceX
and Blue Origin landing rockets now? No. Why do you think that is?


I realise that the software side is the big challenge in making it work
correctly.


You realize many things that are only partly true.


Even given the example
of SpaceX, big players (ULA, ESA) are going with bringing back engine
modules rather than complete stages. Why do you think that is?

This was done before SpaceX demonstrated they could re-use succesfully.


Bull****.


The question is whether ULA and the other "old" providers will now
become more agressive and "upgrade" their plans for next generation
rockets for full re-usability.


The question is whether you're always this stupid or you make a
special effort just for us.


A year from now, if they haven't changed their plans, then yeah, they
will be stuck with legacy business model with little future once lobby
becomes ineffective to get contracts.


A year from now they'll be on the same path. They won't even be
landing engines yet.


It's hard to classify a vehicle that has never flown operationally as
"mission accomplished". New Glenn is very different from New Shepard.

Blue Origin says it wants to scale up capabilities. New Shepard doesn't
have orbital capabilities. But it has landing capability. Hence my
question on how much of that capability developped for a "up/down" joy
ride to 100km altitude are re-usable for New Glen where stage 1 also
drops from non-orbital speed.


Asked and answered. See below.


If New Shepard's technooogies won't translate to New Glenn (for landing
stage 1), then its current exercises are merely to build in-house
expertise so scaling up to New Glenn woudl take much longer.


Asked and answered. See below.


While some knowledge will be transferable, there are significant
things Blue Origin will have to work out.

My question still stands. From the re-entry/landing of stage 1, is the
100km up/down ride similar to what a stage 1 for a real orbital vehicle
experiences?


No.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson