Thanks for the additional data.
So if one applies this hours/dry-lb/flight metric to the Shuttle orbiter
and ET minus the steel solid-booster casings, thus to ~40% of the
overall Shuttle stack dry mass and ~90% of the overall labor hours, the
Orbiter/ET moves up on the vertical hours/dry-lb/flight scale by a
factor of ~2.25X, roughly into line with Atlas and Titan 4.
Mind, I'm not arguing that this is any more appropriate a way to chart
Shuttle by this metric.
It's more a matter of pointing out that hours/dry-lb/flight as a metric
can obscure individual major subsystem labor-intensities when it's taken
as an average of an overall vehicle system that incorporates an unusual
mix of both "dumb" heavy and "smart" lightweight major subsystems. (EG,
half-inch wall steel solid motor casings, mated to a considerable
acreage of silica tiles over low-margin aluminum.)
From another angle, large solids I might guess consume a higher
proportion of their labor hours in factory (not counted by this metric)
rather than on-pad (counted) thus further making systems with large
solids show better by this metric.
And on the gripping hand, this metric does seem to do a good job of
comparing vehicles with similar mixes of structure+systems
sophistication across a range of vehicle sizes, as witness the
instructive groupings of various aircraft.
It could be interesting to see a labor-hours per pound of payload
version of that chart at some point when you've got the time.
Henry
On 2/18/2018 12:04 PM, William Claybaugh wrote:
Henry:
I only have data at the stage level for Shuttle. In that case, the SRB’s accounted for less than 10% of labor hours at the launch site (refurbishment and reloading costs are not included in launch ops).
This seems to me expected: solids are far less complex than liquids and should have lower labor intensity, even segmented solids.
Thus it is not just the higher dry mass of the solids that produces better numbers for Shuttle; they also consume comparatively fewer hours.
When I asked, Le Gall confirmed the same was true for Ariane 5.
Bill
On Sat, Feb 17, 2018 at 9:06 PM Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
OK, thanks for the quick replies. (Though I should have been able to
answer the one about solid casings myself, from the positions on the
horizontal vehicle-dry-mass axis. [smacks forehead] )
Some thoughts on your chart, then. (I've attached it again for others'
reference convenience, I trust you won't mind.)
- Background.
I've found it useful over the years to divide aerospace vehicle dry
masses into two broad categories: Structure, and systems. Structure
should be self-explanatory - load-bearing, containment, partitioning,
etc. Systems includes engines, avionics, actuators - any active
mechanisms.
Both structures and systems range from high-weight low-cost "dumb" to
light-weight high-cost "smart". "Dumb" often also involves high-margin
and/or low-maintenance. "Smart" often also involves low-margin and/or
high-maintenance. (And both spectrums of course tend to shift to the
right over time.)
And systems at any given point on that spectrum will tend to cost
significantly more and require significantly more maintenance per pound
than structures.
- I propose that the different balance between structure and systems
is actually why all the combat aircraft cluster closely on the vertical
axis somewhat above your "sonic" trendline, while the three transport
aircraft are all somewhat below it - despite one of these three being
the supersonic Concorde.
Consider: Military combat aircraft tend to have to carry both middling
payload (ordnance) plus a lot of high-performance systems - sensors etc.
Transports meanwhile focus primarily on payload, with only the
minimum
necessary systems.
So all else being equal transports are going to have a significantly
lower systems-to-structure ratio than combat aircraft, and thus will
also have lower maintenance hours per flight per pound (structures being
lower maintenance per pound than systems, all else equal).
This has some bearing on an SSTO, which like Concorde, will tend to have
very high-performance engines and structure - and the absolute minimum
necessary of other onboard systems.
- Shuttle seems surprisingly low on the vertical Labor Intensity axis
at about the average for space launchers, despite its notoriously high
labor-intensity. But a bit of thought explains that: ~60% of Shuttle's
dry mass is relatively "dumb" steel solid booster casings, which aren't
all that labor-intensive even with NASA in charge. This causes the
labor-hours-per-dry-lb measure to rank it artificially low, relative to
practical labor intensiveness.
- Ditto Ariane 5, to a lesser extent.
- Though that doesn't explain Ariane 4's low labor-intensity. I
might
guess two things there: Genuine adherence by its designers to the KISS
principle (this also applies to Soyuz) plus a heartfelt desire to get as
much as possible done in the factory in France rather than on the pad in
French Guiana. (Either or both may apply to 5 to some lesser extent.)
- Most of the mass being steel booster casings didn't help Titan 4
near enough, possibly due to its chief customer's habit of keeping it on
the pad tinkering with things for a year or more before each launch.
- For expendable launchers in general, a great deal of the final
launch-site integration and test labor that's counted here, for reusable
aircraft takes place in the factory and is not counted. This tends to
stretch the vertical difference between space launchers and aircraft
considerably.
In that vein, it would be instructive to see the Falcon 9 plotted on
this graph, first flight separate from reuse flights. Also to see how
the latter changes with the block 5 design and with experience in
general. Alas, yes, SpaceX is not sharing that very useful competitive
data publicly at this point, oh well.
- Atlas Centaur I take it is the old all-balloon-tanks version? Both
ultra-lightweight and high-maintenance, its very high
labor-intensity-per-lb position makes sense.
Though for comparisons between launchers, a chart of labor hours per
payload pound might be instructive. This chart's format implicitly
penalizes ultra-light structures and systems, which may or may not be
requiring more labor hours but certainly have fewer dry pounds. (To
some extent, the same goes for launchers overall versus aircraft.)
- Loose ends, final thoughts: SR-71's higher-than-fighters
labor-intensity-per-lb make sense, as it was pushing considerably harder
to the "smart" end of the structures/systems spectrum than the fighters
listed.
- X-15, even more so - plus the factor that it was also much farther
down the hand-built few-copies experimental vehicle spectrum, where
minimizing routine maintenance hours takes a back seat to just getting
the darn thing to fly.
- DC-X obviously isn't so high on the labor-intensity-per-lb scale
because of its high performance or lightweight structure. There, I
suspect the extremely limited budget exacerbated the just-get-it-flying
factor's complete predominance over providing for easy maintainability.
Anyway, thanks for posting that!
Henry
On 2/17/2018 3:24 PM, William Claybaugh wrote:
> Henry:
>
> For launch vehicles, ops begin when it arrives at the launch site
> (lands, for Shuttle; ferry flights are included in ops).
>
> I’ve bundled the data here, but in some cases I also have a
breakout for
> “moves from processing to launch pad”. More efficient vehicles
> obviously—in the data—minimize launch pad time.
>
> Words have meaning: dry weight—in this case—means exactly that. No
> propellant was included in the mass estimate.
>
> I have no ops data on F9; I have counted cars at the launch site
which
> has not proven helpful: there are pretty consistently more cars
at that
> site than at ULA’s Atlas pad, go figure.
>
> Bill
>
> On Sat, Feb 17, 2018 at 3:09 PM Henry Vanderbilt
> <hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>
<mailto:hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>>> wrote:
>
> Bill,
>
> "Obviously incorrect" is overdoing the mea culpa. Too
cryptic and
> context-deficient, perhaps. A hazard of posting late and
tired - but
> we've all done that at some point.
>
> My apologies in turn for perhaps once or twice visibly
enjoying myself
> too much during my guessing-what-you-might-mean responses. (Mind, even
> guessing wrong I found them useful; I hadn't revisited those
numbers in
> too long.)
>
> But now that you've posted that chart, there's obviously an
interesting
> point here: Adjusting labor-hours per flight for overall
vehicle dry
> mass does lead to some interesting and instructive
clusterings, and
> potentially clarifies things in the search for factors
affecting vehicle
> ops costs.
>
> Though I do have two questions about your assumptions there:
>
> - For expendables, where did you draw the line between
manufacturing
> man-hours and support man-hours? The logical divide would be
at the
> point where the stages get delivered to the launch site and begin
> pre-launch erection and processing. (Mind, on an expendable,
I could
> see a defensible argument for counting manufacturing hours too.)
>
> - For vehicles with fixed-size large solid boosters
associated -
> Titan
> 4, Ariane 5, Shuttle - did you include the dry mass of the solid
> casings?
>
> Hmm, make that three questions: What do you have on where
Falcon 9 comes
> down on this chart? You did mention some such. (And, where
might F9
> reuse flights fit into that?)
>
>
> Henry
>
> On 2/17/2018 7:22 AM, William Claybaugh wrote:
> > All:
> >
> > My sincere apologies for this obviously incorrect post.
> >
> > There is a four order of magnitude difference in *Labor
Intensity*
> > between subsonic aircraft and space launch systems (see
the attached
> > chart), not in cost per pound.
> >
> > By way of explanation (but not excuse), let me admit too
putting
> in some
> > fairly long hours lately on this SSTO study and being in the
> middle of
> > writing about labor costs when I dashed off this stupid post.
> >
> > My apologies to all,
> >
> > Bill
> >
> > On Fri, Feb 16, 2018 at 2:49 PM, William Claybaugh
> > <wclaybaugh2@xxxxxxxxx <mailto:wclaybaugh2@xxxxxxxxx>
<mailto:wclaybaugh2@xxxxxxxxx ;<mailto:wclaybaugh2@xxxxxxxxx>>
> <mailto:wclaybaugh2@xxxxxxxxx ;<mailto:wclaybaugh2@xxxxxxxxx>
<mailto:wclaybaugh2@xxxxxxxxx ;<mailto:wclaybaugh2@xxxxxxxxx>>>> wrote:
> >
> > Henry:
> >
> > To first order and to date, stuff that goes to orbit
costs about
> > four orders of magnitude more than subsonic stuff, per
pound.
> >
> > SpaceX has pulled about half an order of magnitude out
of that,
> > leaving the difference—in their case only—at almost
exactly four
> > orders of magnitude.
> >
> > Bill
> >
> > On Fri, Feb 16, 2018 at 1:28 PM Henry Vanderbilt
> > <hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>
> <mailto:hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>>
> <mailto:hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>
> <mailto:hvanderbilt@xxxxxxxxxxxxxx
<mailto:hvanderbilt@xxxxxxxxxxxxxx>>>> wrote:
> >
> > Cost-per-airframe/engine pound certainly scales up
with
> higher
> > vehicle
> > performance.
> >
> > Development cost per project has a less linear
> relationship with raw
> > vehicle performance - other significant variables
also apply.
> >
> > See my previous remarks about the different demands of
> achieving a
> > profitable performance increment over existing
> mature-technology
> > ailiner
> > competition, versus developing a Good Enough
version of a
> > radically new
> > space transport approach that inherently brings
with it a
> > significant
> > performance edge.
> >
> > And on the gripping hand, setting up for economic
serial
> > production of
> > hundreds-to-thousands of copies of a big
state-of-the-art
> > airliner is a
> > major expense that developers of advanced rockets
> generally avoid.
> >
> > In fact, SpaceX's investment in reusability can be
viewed as
> > primarily a
> > way to support their high (for the old expendable
industry)
> > flight rates
> > with a much smaller/cheaper booster core production
> > establishment than
> > they'd otherwise need.
> >
> > To a first approximation, a successful Mark 1 version
> > fast-turnaround
> > SSTO space transport will not immediately require mass
> > production. More
> > like single digit numbers of hand-built copies.
> >
> > Later marks, as the market radically expands, will
be a
> > different story.
> > But the revenue from the early marks will be
there to help
> > support
> > establishing higher-rate production. Not an issue for
> funding the
> > initial push to market.
> >
> > Henry Vanderbilt
> >
> > On 2/15/2018 3:15 PM, William Claybaugh wrote:
> > > Rick:
> > >
> > > Productivity gains in the aerospace sector have
pretty
> much
> > matched
> > > inflation over the period since the 747 was
developed;
> > accordingly, a
> > > large passenger aircraft should cost—in today’s
> > dollars—pretty much the
> > > same as a 747 cost in then dollars. $1 Billion
by your
> estimate.
> > >
> > > The other glaring issue here is that a subsonic
> aircraft is not
> > > comparable to a Mach 25 spaceship; trying to
use the
> one to
> > estimate the
> > > cost of the other guarantees underestimating.
> > >
> > > Bill
> > >
> > >
> > >
> > > On Thu, Feb 15, 2018 at 1:42 PM Rick Wills
> <willsrw@xxxxxxxxx <mailto:willsrw@xxxxxxxxx>
<mailto:willsrw@xxxxxxxxx ;<mailto:willsrw@xxxxxxxxx>>
> > <mailto:willsrw@xxxxxxxxx
<mailto:willsrw@xxxxxxxxx> <mailto:willsrw@xxxxxxxxx
<mailto:willsrw@xxxxxxxxx>>>
> > > <mailto:willsrw@xxxxxxxxx
<mailto:willsrw@xxxxxxxxx> <mailto:willsrw@xxxxxxxxx
<mailto:willsrw@xxxxxxxxx>>
> <mailto:willsrw@xxxxxxxxx ;<mailto:willsrw@xxxxxxxxx>
<mailto:willsrw@xxxxxxxxx ;<mailto:willsrw@xxxxxxxxx>>>>> wrote:
> > >
> > > Henry
> > >
> > > I'll throw my 2 cents in here.
> > >
> > > $20B should be an upper limit for
> spaceplane/launch vehicle
> > > development. My estimate is $14B to $17B. A reusable
> > orbital
> > > launch vehicle may or not be an SSTO but
it needs
> to be 100%
> > > reusable. My rational for the estimate is
Boeing
> spent
> > $1 Billion
> > > to develop the 747 with first flight in 1969. Today,
> > that's roughly
> > > $7B. Rough order of magnitude is double
Boeing's
> cost;
> > than add
> > > 20% for cost overruns. I can see why some
people
> might
> > argue $20B
> > > to $40B; Boeing Dreamliner is reported to have
> cost $30B
> > to develop.
> > > However, SpaceX could hit 100% reusable with a
> reusable
> > upper stage.
> > >
> > > On Monday afternoon, I spoke to freshman
> mechanical and
> > aerospace
> > > engineering students at the University of
Dayton
> on the
> > subject of
> > > the Engineering Profession. In my "lessons
learned"
> > section, I
> > > discussed bias. Yep, we all got them. As an
> example, I
> > discussed
> > > my bias about what a reusable orbital
launch vehicle
> > would like. My
> > > long held view was a reusable launch
vehicle would be
> > "aircraft
> > > like": wings, landing gear, etc, and of
course a
> pilot.
> > (full
> > > disclosure, I hold a commercial pilot
rating and am
> > engineer). In
> > > preparing for the talk, I realize this bias
when
> as far
> > back as my
> > > childhood looking at Pratt & Coggins book "By
> Spaceship
> > to the
> > > Moon". It's 1950 technology but the science is
> solid for
> > the time.
> > > In it, there is a nice drawing of a large
winged
> > vehicle, they
> > > called it a supply ship. The vehicle was
taking off
> > horizontally
> > > with a rocket powered sled. My five year
old self
> looked
> > at that
> > > and thought, "that's neat". I now
understand the
> technical,
> > > developmental, political, and financial issues
> with these
> > sorts of
> > > system configurations but the bias was
implanted.
> Now
> > Space X
> > > comes along and shows how recovering an intact
> undamaged
> > first stage
> > > can return a profit. Biases do die hard, but
> it's hard
> > to argue
> > > with success.
> > >
> > > Take Care and Be Safe,
> > >
> > > Rick Wills
> > > Still waiting for Buck Rogers
> > >
> > > -----Original Message-----
> > > From: arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>
> > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>>
> > > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>
> > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>>>
> > > [mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>
> > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>>
> > > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>
> > <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
> <mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>>>>] On Behalf Of Henry
> > Vanderbilt
> > > Sent: Thursday, February 15, 2018 1:54 PM
> > > To: arocket@xxxxxxxxxxxxx
<mailto:arocket@xxxxxxxxxxxxx>
> <mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>>
<mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>
> <mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>>>
> > <mailto:arocket@xxxxxxxxxxxxx
<mailto:arocket@xxxxxxxxxxxxx>
> <mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>>
<mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>
> <mailto:arocket@xxxxxxxxxxxxx ;<mailto:arocket@xxxxxxxxxxxxx>>>>
> > > Subject: [AR] Re: SSTO fuels (was Re: SSTO)
> > >
> > > On 2/13/2018 7:14 PM, William Claybaugh wrote:
> > > > I have seen that paper. For something as
> technically
> > (much less
> > > > economically) difficult as SSTO it seems
a little
> > light: even much
> > > > more detailed analysis doesn’t often
lead to much
> > confidence that I
> > > > ought to recommend dropping $20 or $40
billion
> on one
> > solution
> > > over another.
> > >
> > > My two cents worth: If fielding a useful
SSTO space
> > transport is
> > > costing you $20 to $40 billion, you're
doing something
> > very wrong.
> > >
> > > That's the sort of price tag you get by
farming it
> out to the
> > > existing cost-plus government aerospace houses,
> > supervised by an
> > > existing high-overhead government R&D
bureaucracy.
> > >
> > > At the end of that process you may or may
not get a
> > useful space
> > > transport, but lots of people will have had
decades of
> > low-stress
> > > white-collar job security. Fine if that's your
> objective -
> > > typically if you're a Congressman and
they're your
> > constituents - if
> > > you actually care about building useful space
> > transportation, not so
> > > much.
> > >
> > > Done as previously described, build your own
> private team
> > up doing
> > > methodical risk-reduction then development
(as with
> > SpaceX and Blue)
> > > it should be perhaps a tenth of that.
> > >
> > > Henry V
> > >
> > >
> > >
> >
> >
>