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A Low Cost, All European, Manned Launcher.


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#1 Robert Clark

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Posted 31 March 2012 - 10:09 AM

[This is in reference to an argument attached below that the Ariane 5 core stage
can be SSTO with 3 Vulcain engines.]


The most important accomplishment of SpaceX may turn out to be they showed in
such stark terms the savings possible when launchers are privately financed:

SpaceX Might Be Able To Teach NASA A Lesson.
May 23, 2011
By Frank Morring, Jr.
Washington

“I think one would want to understand in some detail . . . why would it be
between four and 10 times more expensive for NASA to do this, especially at a
time when one of the issues facing NASA is how to develop the heavy-lift
launch vehicle within the budget profile that the committee has given it,”
Chyba says.
He cites an analysis contained in NASA’s report to Congress on the market for
commercial crew and cargo services to LEO that found it would cost NASA
between $1.7 billion and $4 billion to do the same Falcon-9 development that
cost SpaceX $390 million. In its analysis, which contained no estimates for
the future cost of commercial transportation services to the International
Space Station (ISS) beyond those already under contract, NASA says it had
“verified” those SpaceX cost figures.
For comparison, agency experts used the NASA-Air Force Cost Model—“a
parametric cost-estimating tool with a historical database of over 130 NASA
and Air Force spaceflight hardware projects”—to generate estimates of what it
would cost the civil space agency to match the SpaceX accomplishment. Using
the “traditional NASA approach,” the agency analysts found the cost would be
$4 billion. That would drop to $1.7 billion with different assumptions
representative of “a more commercial development approach,” NASA says.

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/05/23/AW_05_23_2011_p36-324881.xml

The SpaceX experience of developing a launcher in the Falcon 9 at 1/10th the
cost of a government financed one also holds for the crew capsule development
costs since the Dragon capsule cost about $300 million to develop while the
Orion costs several billion and still counting. So it can't be said this cost
saving is just due to the Falcon 9 being, so far, unmanned.
Speaking about Orion and billions of dollars, I read an article about plans
to use the Orion on the Ariane 5 to get a European manned spaceflight
capability:

French govt study backs Orion Ariane 5 launch.
By Rob Coppinger
on January 8, 2010 4:45 PM
http://www.flightglo.../01/french.html

This would cost several billion dollars to man-rate the Ariane 5. I have to
believe the solid rocket boosters, which can not be shut down when started,
play a significant role in that high cost. The article mentions also the
core stage would have to be strengthened. But such strengthening is based on
it having to support a 20 mT Orion capsule and a 20 mT upper stage which
wouldn't be used with a much smaller capsule such as the Dragon, at a dry mass
of about 4 mT.
Note also that quite likely an even smaller manned capsule could be designed
at about a 2 mT dry mass to carry a 3 man crew, which given its half size
compared to the Dragon, might cost in the range of only $150 million to
develop as privately financed. It's hard to imagine that private investment
could not be found to finance such a capsule development when it could lead to
a manned European space capability.
In regards to the costs of a privately financed SSTO version of the Ariane
launcher we might make a comparison to the Falcon 9. It cost about $300
million to develop and this includes both the structure and engines, the
engines making up the largest share of the development cost of a launcher. But
for the SSTO Ariane both engine and structure are already developed and it's
only a single stage instead of the two stages of the Falcon 9. You would have
the development cost of adding 2 additional engines and of the new avionics,
but again I have to be believe the development cost would once again be less
than the SpaceX development cost of the Falcon 9 if privately financed.

I also read that the ESA is attempting to decide whether to upgrade the
Ariane 5 or move to a Next Generation Launcher(NGL):

Ariane rocket aims to pick up the pace.
25 June 2011 Last updated at 06:39 ET
http://www.bbc.co.uk...onment-13911901

Thu, 9 February, 2012
France, Germany To Establish Working Group To Resolve Ariane 5 Differences.
By Peter B. de Selding
http://www.spacenews...ifferences.html

If the NGL is chosen then a quite expensive new large engine development
would have to be made, and the launcher might not enter service until 2025. In
contrast the SSTO-Ariane, given that the engine and stage already exist, a
prototype probably could be ready within 1 to 2 years, and moreover by using a
second stage it could also be used to launch the medium sized payloads.

So the SSTO-Ariane would solve the twin problems at low cost of providing
Europe with a manned spaceflight capability and giving it a lower cost medium
lift capability.


Bob Clark



======================================================================
Newsgroups: sci.space.policy, sci.astro, sci.physics, sci.space.history, rec.arts.sf.science
From: Robert Clark
Date: Thu, 8 Sep 2011 13:56:20 -0700 (PDT)
Subject: Re: A kerosene-fueled X-33 as a single stage to orbit vehicle.

I saw this discussed on a space oriented forum:

WSJ: Europe Ends Independent Pursuit of Manned Space Travel.
"LE BOURGET, France—Europe appears to have abandoned all hope of
independently pursuing human space exploration, even as the region's
politicians and aerospace industry leaders complain about shrinking
U.S. commitment to various space ventures.
"After years of sitting on the fence regarding a separate, pan-
European manned space program, comments by senior government and
industry officials at the Paris Air Show here underscore that budget
pressures and other shifting priorities have effectively killed that
longtime dream."
http://www.orbiter-f...ead.php?t=23006

In this post I discussed getting a SSTO by replacing the Vulcain
engine on the Ariane 5 core with a SSME:

Newsgroups: sci.space.policy, sci.astro, sci.physics, sci.space.history
From: Robert Clark
Date: Wed, 23 Feb 2011 10:14:42 -0800 (PST)
Subject: Re: Some proposals for low cost heavy lift launchers.
http://groups.google...586cc269f?hl=en

However, in point of fact Europe can produce a manned launch vehicle
from currently *existing*, European components. This will consist of
the Ariane 5 and three Vulcain engines. The calculations below use the
Ariane 5 generic "G" version. You might need to add another Vulcain
for the larger evolution "E" version of the Ariane 5 core.
In a following post I'll also show that the Hermes spaceplane also
can become a SSTO by filling the entire fuselage aft of the cockpit
with hydrocarbon propellant.
The impetus for trying the calculation for a Ariane 5 core based SSTO
using Vulcains instead of the SSME was from a report by SpaceX that
you could get the same performance from a planned heavy lift first
stage using a lower performance Merlin 2 compared to the high
performance RS-84 engine. The reason was the lower Isp of the Merlin
was made up for by its lower weight.

THIS IS A VERY IMPORTANT FACT BECAUSE WHAT IT MEANS IS THAT YOU DON'T
NEED THE HIGH PERFORMANCE ENGINES TO GET THE SSTO. YOU CAN USE ENGINES
OF LOWER CHAMBER PRESSURE AND SIMPLER COMBUSTION CYCLES, SUCH AS THE
VULCAIN WITH A CA. 100 BAR COMBUSTION PRESSURE AND A GAS GENERATOR
CYCLE. THIS MEANS THE ENGINES ARE CHEAPER, EASIER TO MAKE REUSABLE,
REQUIRE LESS ROUTINE MAINTENANCE, AND CAN LAST FOR MANY RESTARTS.

In the discussion of the Ariane/Vulcain SSTO below, I note you can
get a prototype, test vehicle quite quickly since the components are
already existing. To improve the payload though you would want to use
altitude compensation on the Vulcains. In a following post I'll
discuss some methods of altitude compensation.
In regards to achieving this at low cost, I think the most important
accomplishment of SpaceX might turn out to be that they showed in
stark terms that privately financed spacecraft, both launchers and
crew capsules, can be accomplished at 1/10th the developmental cost of
government financed ones. Imagine a manned, reusable orbital launcher,
for example, instead of costing, say, $3 billion, only costing $300
million to develop.
Here's how you can get an all European manned SSTO using the Ariane 5
core stage but with Vulcain engines this time. Note that this is one
that can be produced from currently existing components, aside from
the capsule, so at least an unmanned prototype vehicle can be
manufactured and tested in the short term and at lowered development
cost.
We'll use three Vulcain 2's instead of the 1 normally used with the
Ariane 5 core stage. There are varying specifications given on the
Vulcain 2 depending on the source. I'll use the Astronautix site:

Vulcain 2.
http://www.astronaut...es/vulcain2.htm

From the sea level thrust given there, using three Vulcain 2's will
give us one engine out capability. The weight is given as 1,800 kg. So
adding on two will take the dry mass from 12 mT to 15.6 mT.
To calculate the delta-V achieved I'll use the idea again to just use
the vacuum Isp, but adding the loss due to back pressure onto the
delta-V required for orbit, as I discussed previously. However, here
for hydrogen fuel which has higher gravity loss, I'll use a higher
required delta-V of 9,400 m/s when you add on the back pressure loss.
With the vacuum Isp given for the Vulcain 2 of 434 s, we get a payload
of 3.8 mT:

434*9.8ln(1+158/(15.6+3.8)) = 9,412 m/s.

Note this is just using the standard nozzle Isp for the Vulcain, no
altitude compensation. So this could be tested, like, tomorrow.
However, for a SSTO you definitely want to use altitude compensation.
Using engine performance programs such as ProPEP we can calculate that
using long nozzles, you can get a vacuum Isp of 470 s for this engine.
As a point of comparison of how high an Isp you can get even with a
low chamber pressure engine as long as you have a long nozzle, or
equivalent, note that the RL10-B2 with a ca. 250 to 1 area ratio, and
only a ca. 40 bar chamber pressure, gets a 465 s vacuum Isp. So we'll
assume we can get a comparable Isp by using altitude compensation.
This allows us to get payload of 8 mT:

470*9.8ln(1+158/(15.6+8) = 9,400 m/s.

This allows us to add a Dragon-sized capsule and also the reentry and
landing systems to make it reusable.


Bob Clark
======================================================================

Edited by Robert Clark, 31 March 2012 - 10:10 AM.


#2 Robert Clark

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Posted 03 August 2012 - 02:04 PM

I've been arguing that SSTO's are actually easy because how to achieve
them is perfectly obvious: use the most weight optimized stages and
most Isp efficient engines at the same time, i.e., optimize both
components of the rocket equation. But I've recently found it's even
easier than that! It turns out you don't even need the engines to be
of particularly high efficiency.
SpaceX is moving rapidly towards testing its Grasshopper scaled-down
version of a reusable Falcon 9 first stage:

Reusable rocket prototype almost ready for first liftoff.
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: July 9, 2012
http://www.spaceflig.../10grasshopper/

SpaceX deserves kudos for achieving a highly weight optimized Falcon 9
first stage at a 20 to 1 mass ratio. However, the Merlin 1C engine has
an Isp no better than the engines we had in the early sixties at 304
s, and the Merlin 1D is only slightly better on the Isp scale at 311 s.
This is well below the highest efficiency kerosene engines (Russian)
we have now whose Isp's are in the 330's. So I thought that closed
the door on the Falcon 9 first stage being SSTO.

However, I was surprised when I did the calculation that because of
the Merlin 1D's lower weight, the Falcon 9 first stage could indeed be
SSTO. For the calculation we'll need the F9 dry mass and propellant
mass. I'll use the Falcon 9 specifications estimated by GW Johnson, a
former rocket engineer, now math professor:

WEDNESDAY, DECEMBER 14, 2011
Reusability in Launch Rockets.
http://exrocketman.b....h-rockets.html

The first stage propellant load is given as 553,000 lbs, 250,000 kg,
and the dry weight as 30,000 lbs, 13,600 kg.

I'll actually calculate the payload for the first stage of the new version of
the Falcon 9, version 1.1. The Falcon Heavy will use this version's first stage
for its core stage and side boosters. SpaceX expects the Falcon 9 v1.1
to be ready by the end of the year.

Elon Musk has said version 1.1 will be about 50% longer:

Q&A with SpaceX founder and chief designer Elon Musk.
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: May 18, 2012
http://www.spaceflig...003/120518musk/

I'll assume this is coming from 50% larger tanks. This puts the
propellant load now at 375,000 kg. Interestingly SpaceX says the side
boosters on the Falcon Heavy will have a 30 to 1 mass ratio. This
improvement is probably coming from the fact it is using the lighter
Merlin 1D engines, and because scaling up a rocket actually improves
your mass ratio, and also not having to support the weight of an upper
stage and heavy payload means it can be made lighter.

So I'll assume for this SSTO version of the Falcon 9 v1.1 the mass
ratio is 30 to 1, which makes the dry mass 13 mT.

To estimate the payload I'll use the payload estimation program of
Dr. John Schilling:

Launch Vehicle Performance Calculator.
http://www.silverbir.../LVperform.html

It actually gives a range of likely values of the payload. But I've found
the midpoint of the range it specifies is a reasonably accurate estimate
to the actual payload for known rockets.

Input the vacuum values for the thrust in kilonewtons and Isp in
seconds. The program takes into account the sea level loss. SpaceX
gives the Merlin 1D vacuum thrust as 161,000 lbs and vacuum Isp
as 311 s:

FALCON 9 OVERVIEW.
http://www.spacex.com/falcon9.php

For the 9 Merlins this is a thrust of 9*161,000lb*4.46N/lb = 6,460
kN. Use the default altitude of 185 km and select the Cape Canaveral
launch site, with a 28.5 degree orbital inclination to match the
Cape's latitude.

Input the dry mass of 13,000 kg and propellant mass of 375,000 kg.
The other options I selected are indicated here:

Posted Image

Then it gives an estimated 7,564 kg payload mass:

=====================================
Launch Vehicle: User-Defined Launch Vehicle
Launch Site: Cape Canaveral / KSC
Destination Orbit: 185 x 185 km, 28 deg
Estimated Payload: 7564 kg
95% Confidence Interval: 3766 - 12191 kg
=====================================

This may be enough to launch the Dragon capsule, depending on the mas
of the Launch Abort System(LAS).


Bob Clark

#3 CraigD

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Posted 03 August 2012 - 06:19 PM

Launch Vehicle Performance Calculator.
http://www.silverbir.../LVperform.html

:thumbs_up That’s a neat little calculator, though I wish its “methodology used” page showed its actual code. I enjoy writing simple simulators myself, and posted the code for a few in the space forum years ago, before my and others interest and enthusiasm in writing a really useful, more complicated one fizzled out. Though I expect there are lots of tried and true simulators practically or fully in the public domain, there’s no substitute, IMHO, for writing your own. :)

I’m a bit wary of accepting its calculations showing SSTO-capability using SpaceX Falcon rockets, as if this were truly the case, I’d expect SpaceX, not a company shy of making grand promises, and one I’m sure has excellent high detail simulators, would have made it known years or more ago.

Until actually running a detailed simulation, I have to remain skeptical – not of the possibility of SSTO, but of how easy calculators like this suggest it is.

SpaceX is moving rapidly towards testing its Grasshopper scaled-down
version of a reusable Falcon 9 first stage:

Reusable rocket prototype almost ready for first liftoff.
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: July 9, 2012
http://www.spaceflig.../10grasshopper/

I’ve been enthused since first reading of SpaceX’s ambitions to make the currently disposable Dragon reusable via the oh so cool sounding means of landing them with their own main engines, and am delighted to see serious work being done toward that.

I’m wary, though, of statements like these, from the article:


"If one can figure out how to effectively reuse the rockets just like an airplane, the cost of access to space will be reduced by as much as a factor of a hundred," [SpaceX CEO and founder Elon] Musk said. "A fully reusable vehicle has never been done before. That really is the fundamental breakthrough that is needed to revolutionize access to space."

This “dramatically reduce cost through reusability” argument seems pretty much the same as the one made in the 1970s in promotion of the STS (Space Shuttle, or as it was often promoted as “space truck” system), which, with the exception of a single component, its engineless external fuel tank, was a fully reusable system, yet proved to be more expensive than many disposable systems, because of the great cost of reconditioning its reusable hardware after each use.

The analogy of an airplane to a rocket can be a deceptive one, in greatest part because airplane engines and other components are designed for durability, at the expense of greatest power/mass ratios. A typical jet aircraft engine need be overhauled every 3000 to 5000 hours, vs. (using the Shuttle as an example) every 8 to 10 minutes for rocket engines.

Though the reduced cost through reusability argument is intuitively appealing, precisely because of our experience with airplanes, cars, and other vehicles with very durable engines and other parts. High Isp rocket motors are machines of a quite different sort.

Like any decent space fan, a SSTO vehicle as cheap and reliable as the car in my driveway (or plane in my hanger, if I was one of the many folk fortunate enough to have one) is among my fondest dreams. But I’ve learned to beware of intuitively appealing mantras like “just make it reusable, like an airplane,” even when the person saying them is someone like the uber-cool Elon Musk.

I think that if reusable SSTO (or multi-reusable stage to orbit) is ever to really reduce the dramatically cost of spaceflight, more attention needs to be given to making rocket motors so durable that they can be reused without significant reconditioning work. As I see things now, informed by the experience of the disappointingly costly STS program, it’s little, if at all, cheaper to reuse a rocket than to build a new one from scratch.

#4 Robert Clark

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Posted 27 August 2012 - 04:44 PM

:thumbs_up That’s a neat little calculator, though I wish its “methodology used” page showed its actual code. I enjoy writing simple simulators myself, and posted the code for a few in the space forum years ago, before my and others interest and enthusiasm in writing a really useful, more complicated one fizzled out. Though I expect there are lots of tried and true simulators practically or fully in the public domain, there’s no substitute, IMHO, for writing your own. :)
I’m a bit wary of accepting its calculations showing SSTO-capability using SpaceX Falcon rockets, as if this were truly the case, I’d expect SpaceX, not a company shy of making grand promises, and one I’m sure has excellent high detail simulators, would have made it known years or more ago.
Until actually running a detailed simulation, I have to remain skeptical – not of the possibility of SSTO, but of how easy calculators like this suggest it is.
...


Thanks for the informative response. It's all theoretical until Spacex fields the Falcon 9 v1.1 later this year and the Falcon Heavy including those side boosters next year.
If the Falcon 9 v1.1 first stage mass ratio is anywhere close to 30 to 1, as SpaceX claims the FH side boosters will be, then that will raise the questions about whether it can be SSTO.
If it can be, then that raises the possibility that by using higher efficiency engines such as the NK-33 or RD-180 we can get an economic SSTO even with reusability.

Bob Clark