Falcon 9 First Stage Return During ORBCOMM Mission

Jeff Findley wrote:
In article ,
says...

At this point, we are highly confident of being able to land
successfully on a floating launch pad or back at the launch site
and refly the rocket with no required refurbishment.

Isn't that last bit a tad, well, optimistic? Have they really
recovered enough of these things to know there won't be any
refurbishment required? I would have thought that actually getting
one back fully intact would be something of a pre-requisit for
determining no refurbishment was required.

I'd say so, at least for "land successfully on a floating launch
pad". Unless we're talking about something as stable as a platform
like those used in oil drilling, the "floating launch pad" is going
to be bobbing around in the sea, making landing on it quite a bit
more difficult than a fixed landing pad. We'll have to wait until
Flights 14 and 15 to see exactly what SpaceX is going to try next.

Well, there is that, but I was actually referring to the "no required
refurbishment" assertion.

rick jones
--
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In article , says...

Well, there is that, but I was actually referring to the "no required
refurbishment" assertion.

As long as the Merlin engines were designed from the start to be truly
reusable (which I suspect they were), then I don't see why a Falcon 9
V1.1 first stage would be much harder to quickly re-fly than DC-X. DC-X
proved it was possible two decades ago and that was with the additional
(cryogenic) headaches caused by using LH2 as a fuel.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

Jeff Findley wrote:
In article , says...

Well, there is that, but I was actually referring to the "no required
refurbishment" assertion.

As long as the Merlin engines were designed from the start to be
truly reusable (which I suspect they were), then I don't see why a
Falcon 9 V1.1 first stage would be much harder to quickly re-fly
than DC-X. DC-X proved it was possible two decades ago and that was
with the additional (cryogenic) headaches caused by using LH2 as a
fuel.

Fair enough - but in the case of DC-X they were able to look at the
engines etc after each of the tests. And I'm not questioning the
principle of "no refurb" reuse as much as the "confidence" assertion.
Unless one includes Grasshopper (which may indeed be applicable here
at least to a point) I would think that having confidence in knowing
there will be no refurb required would call for examining a few
successfully recovered stages. Sure, they've brought two stages to
sea level (more or less) but just how much of those stages have they
been able to examine?

rick
--
Don't anthropomorphize computers. They hate that. - Anonymous
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

Rick Jones explained on 7/22/2014 :
David Spain wrote:
The following video of the F9 first stage return was just posted to
YouTube today by SpaceX. The video is abbreviated 1/2 way through I
suppose to skip the boring multi-minute reentry part and finished
with the deployment of the landing legs and tip-over as the stage
hits the water.

https://www.youtube.com/watch?v=CQnR5fhCXkQ

Kind of interesting to this observer from the peanut gallery how the
exhaust plume (term?) isn't nearly so neat and tidy on the way down as
it was on the way up.

Well, it is blowing into the wind on the way down. On the way up, it
uses the booster body as a windshield.

/dps

--
The presence of this syntax results from the fact that SQLite is really
a Tcl extension that has escaped into the wild.
http://www.sqlite.org/lang_expr.html

Wednesday, Jeff Findley quipped:
In article ,
says...
David Spain wrote:

The following video of the F9 first stage return was just posted to
YouTube today by SpaceX. The video is abbreviated 1/2 way through I
suppose to skip the boring multi-minute reentry part and finished
with the deployment of the landing legs and tip-over as the stage
hits the water.

https://www.youtube.com/watch?v=CQnR5fhCXkQ

Kind of interesting to this observer from the peanut gallery how the
exhaust plume (term?) isn't nearly so neat and tidy on the way down as
it was on the way up.

Which is what one would expect when the exhaust plume is pointed
opposite the direction of the velocity vector.

I guess I didn't read ahead as far as I thought I had.

/dps

--
Ieri, oggi, domani

In article ,
says...

Jeff Findley wrote:
In article , says...

Well, there is that, but I was actually referring to the "no required
refurbishment" assertion.

As long as the Merlin engines were designed from the start to be
truly reusable (which I suspect they were), then I don't see why a
Falcon 9 V1.1 first stage would be much harder to quickly re-fly
than DC-X. DC-X proved it was possible two decades ago and that was
with the additional (cryogenic) headaches caused by using LH2 as a
fuel.

Fair enough - but in the case of DC-X they were able to look at the
engines etc after each of the tests. And I'm not questioning the
principle of "no refurb" reuse as much as the "confidence" assertion.
Unless one includes Grasshopper (which may indeed be applicable here
at least to a point) I would think that having confidence in knowing
there will be no refurb required would call for examining a few
successfully recovered stages. Sure, they've brought two stages to
sea level (more or less) but just how much of those stages have they
been able to examine?

It all depends on how confident SpaceX is with their hardware. Not only
does Grasshopper (and the follow-on Falcon 9R first stage test vehicle)
use the same engine(s) and other hardware as a flight stage, but SpaceX
has done numerous test stand runs of its Merlin engines. As a
consequence of all this testing, they know quite well if their engines
are capable of rapid reuse.

Also note that there is nothing fundamental that limits a liquid fueled
rocket engine to a single use. Even "expendable" engines are typically
qualified for longer burn durations and multiple starts to allow for
testing before flight. But, some engines do have design compromises
which limit this somewhat. For example, SSMEs leave much of the
hardware needed to start them at the launch pad, so even "air start" for
the initial Ares-I design was problematic. Other engine designs may
incorporate a pyrotechnic igniter which is single use.

Surely SpaceX has designed Merlin engines with enough margin for rapid
reuse since that was their intent from the beginning. That's one of the
reasons they didn't opt for a more complex, higher pressure, higher ISP,
regen engine design (e.g. RD-180 or SSME). If you're optimizing for
reuse, traditional measures of "performance" is an area where you
deliberately compromise.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

"Jeff Findley" wrote in message
l-september.org...

In article ,
says...

Jeff Findley wrote:
In article ,
says...

Well, there is that, but I was actually referring to the "no required
refurbishment" assertion.

As long as the Merlin engines were designed from the start to be
truly reusable (which I suspect they were), then I don't see why a
Falcon 9 V1.1 first stage would be much harder to quickly re-fly
than DC-X. DC-X proved it was possible two decades ago and that was
with the additional (cryogenic) headaches caused by using LH2 as a
fuel.

Fair enough - but in the case of DC-X they were able to look at the
engines etc after each of the tests. And I'm not questioning the
principle of "no refurb" reuse as much as the "confidence" assertion.
Unless one includes Grasshopper (which may indeed be applicable here
at least to a point) I would think that having confidence in knowing
there will be no refurb required would call for examining a few
successfully recovered stages. Sure, they've brought two stages to
sea level (more or less) but just how much of those stages have they
been able to examine?

It all depends on how confident SpaceX is with their hardware. Not only
does Grasshopper (and the follow-on Falcon 9R first stage test vehicle)
use the same engine(s) and other hardware as a flight stage, but SpaceX
has done numerous test stand runs of its Merlin engines. As a
consequence of all this testing, they know quite well if their engines
are capable of rapid reuse.


I suspect that the first reflights of a Falcon 9R will be "free/cheap"
payload flights.

While SpaceX may be confident, I doubt customers will be.



Also note that there is nothing fundamental that limits a liquid fueled
rocket engine to a single use. Even "expendable" engines are typically
qualified for longer burn durations and multiple starts to allow for
testing before flight. But, some engines do have design compromises
which limit this somewhat. For example, SSMEs leave much of the
hardware needed to start them at the launch pad, so even "air start" for
the initial Ares-I design was problematic. Other engine designs may
incorporate a pyrotechnic igniter which is single use.


Yeah, some of the F-1s had some impressive run-times.

And of course the SSMEs, as finicky as they were ran up some impressive run
times.

SSME s/n 2012 had 22 flights (as of STS-100, not sure about after that)

That's about 3 hours of run-time.

I suspect the Merlins will do far better than that, especially being simpler
engines.


Surely SpaceX has designed Merlin engines with enough margin for rapid
reuse since that was their intent from the beginning. That's one of the
reasons they didn't opt for a more complex, higher pressure, higher ISP,
regen engine design (e.g. RD-180 or SSME). If you're optimizing for
reuse, traditional measures of "performance" is an area where you
deliberately compromise.



Jeff

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

On 7/24/2014 1:36 PM, Greg (Strider) Moore wrote:


"Jeff Findley" wrote in message
...

In article ,
says...
Fair enough - but in the case of DC-X they were able to look at the
engines etc after each of the tests. And I'm not questioning the
principle of "no refurb" reuse as much as the "confidence" assertion.
Unless one includes Grasshopper (which may indeed be applicable here
at least to a point) I would think that having confidence in knowing
there will be no refurb required would call for examining a few
successfully recovered stages. Sure, they've brought two stages to
sea level (more or less) but just how much of those stages have they
been able to examine?

It all depends on how confident SpaceX is with their hardware. Not only
does Grasshopper (and the follow-on Falcon 9R first stage test vehicle)
use the same engine(s) and other hardware as a flight stage, but SpaceX
has done numerous test stand runs of its Merlin engines. As a
consequence of all this testing, they know quite well if their engines
are capable of rapid reuse.


I suspect that the first reflights of a Falcon 9R will be "free/cheap"
payload flights.

While SpaceX may be confident, I doubt customers will be.


Greg I agree with that up until about flight 7 or so. After that, I
think the customer view will switch 180 degrees. And SpaceX will soon
discover discount pricing will be needed to convince customers to fly on
the NEW (i.e. untested) rockets! After all, this attitude is unique to
the rocket biz. You don't see people clamoring to ride in first run
hardware in the aviation biz. Even new jets get test flown a few times
before being turned over to paying customers. It *is* exciting to see
this becoming a reality in the space biz as well.

Dave

On 7/25/2014 8:25 AM, David Spain wrote:

Greg I agree with that up until about flight 7 or so.

Make that "re-flight" 7 or so...

Dave

I suppose that the engines are the "long pole in the re-use tent" but
are they really that much longer than all the other poles?

rick
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...