Non-renewable SLS Core Booster Engines?

I was reading in the NASA Space Flight website about the assignment of veteran RS25D engines for the first SLS mission and in the course of reading that article one thing wasn't clear to me. KSC has supplied a total of 15 RS25's, I presume most were culled from the shuttle fleet (some were not) and modified as needed for SLS. What wasn't clear to me in the article was if there is intended any build-out of new RS25's. Anyone here know? Or are we just cannibalizing the Space Shuttle Engine fleet for SLS until we run out? There are enough engines available for all (the handful of) SLS missions currently on the drawing board. So once modified SSME's are all expended and ditched into the ocean is that the end of SLS?

If so, nice plan for getting rid of one of our technologically most sophisticated rocket engines ever designed in the US. I hope there is at least a plan to retain one or two of these for our future rocket designers.

I sincerely hope I'm wrong. But if not, yet another reason why I so completely despise SLS.

David

Original article I'm talking about can be found he

http://www.nasaspaceflight.com/2014/...maiden-flight/

In article ,
says...

What wasn't clear to me in the article was if there is
intended any build-out of new RS25's.

The short answer is "NASA doesn't know yet", which is quite
disappointing to me. The long answer is that NASA has two choices:

1. Restart the production of RS-25D engines (essentially the same as
used on the shuttle). These would be expensive to make, since the
manufacturing technologies involved are now decades old.
2. Develop RS-25E and pay a much higher up front cost for developing a
"new" engine. The upside to this alternative is that the new engine
should be cheaper to manufacture due to the use of "state of the art"
manufacturing techniques.


Here is a thread about the RS-25E:

http://forum.nasaspaceflight.com/ind...?topic=28164.0

Here is a GAO report from the above thread:

http://www.gao.gov/assets/670/663071.pdf

From the report above:

NASA anticipates a re-start of the production line for
the RS-25 engine that it plans to use to power the
Block IA/B and Block II vehicles [...] but it has not
yet finalized acquisition plans to manufacture them.
According to agency officials, re-starting the
production line would entail at least 3 years, whereas
development of a new engine would require a minimum of
8 years.

Which way to go will surely depend on funding and how many flights are
anticipated for SLS. If it isn't going to fly very often, then the high
cost of developing the RS-25E doesn't make sense, because it would never
"pay for itself".

SLS just keeps getting "better" the more we find out about it, doesn't
it? :-P

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

On Wednesday, May 14, 2014 2:09:27 PM UTC-4, Jeff Findley wrote:
In article ,

says...



What wasn't clear to me in the article was if there is

intended any build-out of new RS25's.



The short answer is "NASA doesn't know yet", which is quite

disappointing to me. The long answer is that NASA has two choices:


or nasa does the right thing, scrap SLS and go with falcon reusable boosters, cutting costs by what 80%?

In article ,
says...

On Wednesday, May 14, 2014 2:09:27 PM UTC-4, Jeff Findley wrote:
In article ,

says...
What wasn't clear to me in the article was if there is
intended any build-out of new RS25's.

The short answer is "NASA doesn't know yet", which is quite
disappointing to me. The long answer is that NASA has two choices:

or nasa does the right thing, scrap SLS and go with falcon reusable
boosters, cutting costs by what 80%?

Falcon "reusable boosters" do not quite exist yet. Falcon 9 v1.1 has a
first stage that is in the process of evolving to become a reusable
first stage. Work on making the second stage reusable is very
preliminary.

SLS, on the other hand, is Congressionally mandated and NASA cannot
simply "scrap SLS" as you suggest. Politics. Don't like it, write and
call your Congressman and Senator. Even better, when they are back in
your district shaking hands and looking for votes, see if you can ask
them directly to please vote against any further money being spent on
SLS. That's the only way to kill SLS.

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

On Thursday, May 15, 2014 10:41:14 AM UTC-4, Jeff Findley wrote:
SLS, on the other hand, is Congressionally mandated and NASA cannot

simply "scrap SLS" as you suggest. Politics. Don't like it, write and

call your Congressman and Senator. Even better, when they are back in

your district shaking hands and looking for votes, see if you can ask

them directly to please vote against any further money being spent on

SLS. That's the only way to kill SLS.



Jeff

--

And the sooner this can be done before all our inventory of RS25's end up at the bottom of the Atlantic, the better.

Dave

In article ,
says...

And the sooner this can be done before all our inventory of RS25's
end up at the bottom of the Atlantic, the better.

My preferred location for the RS-25 engines would be attached to the
space shuttles in the museums in place of the fake engines they have
now. The RS-25 was a remarkable engine, in the late 1970's. Today, not
so much. The manufacturing techniques used are quire dated by todays
standards, resulting in a difficult (expensive) to manufacture engine.

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

My preference would be that if they are to be "reused and discarded" to have them used in an upper stage of a ex-atmospheric transport. Where we might actually get something useful accomplished rather than just redoing heavy lift but in a more expensive and non-repeatable way. But that is just a preference on my part. I certainly can't argue against their expense to manufacture.

The Falcon reuses the pintle fed engines developed for the Lunar Excursion Module, so there's no reason not to take pieces and parts that make sense to future designers. It will all be on computer 3D models, all available for detailed simulation on supercomputers, and all manufactured using 3D printing technologies that make current techniques pale by comparison.

http://www.scribd.com/doc/7244552/Tu...Rocket-Engines

So, I have no worries for the future.

An External Tank has a total volume of 2,433.18 cubic meters, including the LOX tank, the LH2 tank and the Intertank.

It masses 26.5 metric tons.

The AJ10-118K engine from Aerojet General used on the Delta II uses N2O4 A-50 propellant combination. Its pressure fed, however Aerojet still advertises on their website, the LR-87.

The LR-87 is a double chambered engine fed by a common pumpset. This engine propelled by N204 A-50 combination also operated at 54 bar and produce 259 sec Isp at sea level and 297 sec Isp at altitude. It produced 956.5 kN at lift off and 1096.8 kN at altitude. It weighs 739 kg and uses 750 kg/sec of fuel. Mass ratios of fuel to oxidizer is 2:1 - volume ratios are 1.24:1 An average specific gravity of 1.21x that of water (1.21 kg/litre)

N2O4 A-50 propellant combination costs $0.15 per kg (in China ($6.00 per kg in USA due to environmental regulations))

* * *

Alright, so consider 2,433.18 cubic meters filled with a propellant combination at a density of 1210 kg/m3. We rebuild the tank with a common bulkhead replacing the intertank region. This reduces mass. We don't need to store cryogens. This also reduces mass. Still let's keep the 26,500 kg for the tank weight. The mass of propellant on board is 2,944,147.8 kg! This is a structural fraction of 0.9% !!

To lift this system from Earth at 1.4 gees requires 40,420,705.7 Newtons. This is equivalent to 42.3 pumpsets of the type used by the LR-87. At 739 kg each 43 of these engines mass a total of 31,777 kg. Another 1.08% structure fraction!

The 8.4 m diameter tank has a circumference of 26.38 meters. Thus, with 0.6 m spacing between the pump sets, all 43 fit radially under the tank feeding an annular aerospike engine that produces 40.42 MN (4.12 million kgf) thrust.

With an empty mass of 26,500 kg + 31,777 kg = 58,277 kg total and a full mass of 3,002,424.8 kg and an exhaust speed of 297 * 9.80655 = 2,912.5 m/sec this system achieves

2,912.5 * LN(3,002,424.8 / 58,277) = 11,481.1 m/sec !!

If launched from China or India propellant would cost $441,622 per tank fill up.

* * *

Three of these tanks equipped with cross feed could place 325,000 kg (715,000 lbs) into the same orbits as the space shuttle!

http://heroicrelics.org/info/titan-i...1-engines.html

Built in India or China today at a cost of $15 million for the tank and $35 million for the engines and electronics, this is $50 million per vehicle. $150 million for the set. $1.5 million for propellant. $3.5 million for the use of the launch centre. $155 million total cost to put up 325,000 kg - without reuse. $476.92 per kg or $216.78 per lb.

Capable of five reuses, reduces these costs accordingly..

* * *

Seven tanks with four feeding a first stage operation, two feeding a second stage operation, and one feeding the third stage operation, is capable of putting 820,000 kg into orbit.

Seven tanks, with engine sets, cost $350 million. Capable of 20 reuses these cost $17.5 million per launch for the hardware. Adding in $3.5 million for the propellant, $4 million for the launch centre, this is $25 million per launch. This is $30.49 per kg ($13.86/lb).

* * *
SOLAR POWER SATELLITE
* * *

A 3.7 um thick biaxially oriented PET film. With one hemisphere clear, and one hemisphere 0.2 um thick aluminiumized layer. PET masses 1380 kg per cubic meter whilst aluminium masses 2700 kg/m3. The mass of this system is 0.018 kg/m2 of surface area. A hydrogen atmosphere at 1/100,000th bar is 8..4e-7 kg/m3

So, the mass of a sphere is given by

M = 0.017 kg/m2 * D^2 + 4.4e-7 * D^3

Thus, 820,000 kg can lift a 6,000 meter diameter satellite that intercepts 38.7 GW of solar power. Converted with thin disk lasers to laser energy with 80% efficiency this satellite generates 30.9 GW of laser power across the visible and infrared spectrum to which the atmosphere is transparent.

The balloon itself is 612,000 kg. 95,040 kg of hydrogen is used to inflate the sphere. The carrier satellite and other hardware is 112,960 kg.

The reflective film has 1 um wide grooves formed in it that create Fresnel reflectors that adjust the spherical aberration so that the sunlight comes to a sharp focus to an image plane 150 meters across. Illuminating a thin disk laser at 1,600x ambient light intensity.

This 1 mm thick array of 302,300 hexagons 300 mm across masses 41,160 kg.

The laser beams range in wavelength from 1,164 nm to 380 nm. A 150 meter diameter objective beaming 1,164 nm 35,786 km creates an Airy disk some

35,786 * 1.22 * 1164e-9 / 150 = 363 mm in diameter!

So, a 450 mm diameter hexagon can receive the energy beamed from the solar pumped thin disk laser! In fact a large number of receivers may operate simultaneously.

At $2,200 per kg for the payload, and 820,000 kg, the payload cost is $1.8 billion.

30 GW x 8766 hours per year = 262,980 million kWh.

$1.8 billion borrowed at 6.25% interest for 30 years costs $134.29 million per year. This is 0.051 cents per kWh!!

At $0.03 per kWh delivered directly to where its needed, this generates $7.9 billion per year!

Each GWh generates 24.38 tonnes of hydrogen from 228.49 kiloliters of water.. Thus, in a year this satellite, if devoted solely to making hydrogen gas, generates 6.41 million tonnes of hydrogen gas from water.

A tonne of hydrogen is equal to 3.376 tonnes of crude oil. So, at $688.52 per tonne this is equivalent to $14.9 billion per year.

Methanol can be made from hydrogen

4 CO2 + 8 H2 → 4 CH3OH + 2O2
11 1 8 4

Which makes 51.28 million tonnes of methanol from 70.51 million tonnes of CO2 from the air. This is equivalent to 19 million tonnes of crude oil. At $688.52 per tonne this is worth $13.08 billion!

In 2013 according to the IEA the world consumed 13,113 million metric tons of crude oil equivalent. At 42 GJ/tonne and dividing by 30 GJ and the number of seconds in a year this is provided by 582 satellites in Geosynch orbit around the Earth each spaced 350 km apart. At 3 flights per day these are deployed in less than 7 months.

With a 7 day turn around, this requires 21 flight systems, 147 flight elements.

* * *
MOON SHIP
* * *

An 820,000 kg stage to move from LEO to Trans-Lunar-Injection must at 2.95 km/sec to its speed. This requires a propellant fraction of 62.1% thus 509,220 kg of propellant is needed. The tank masses 15,275 kg and is 8.4 km in diameter and 10.4 km long. This leaves 295,505 kg to land on the moon.

To land on the moon and take off, requires a delta vee of 4.7 km/sec. This requires a propellant fraction of 78.7%. Thus 232,562 kg of propellant is needed. A spherical tank 7.16 m in diameter. The tank masses 4,650 kg. Thus, 58,293 kg may be taken to the moon and back to Earth.

This supports a base of 73,000 persons.

* * *
ADVANCED PROPULSION
* * *

A 30 GW laser beam heating a propellant to an exhaust velocity of 20 km/sec produces 305,917 kgf of thrust. Thus, an 820,000 kg payload may be accelerated at 0.373 gees. This is sufficient to land and take off from the moon which has a surface gravity of 0.167 gees. Thus, to propel the spacecraft from LEO to TLI and then land on the moon and return to Earth, requires a propellant fraction of 31.8% and so, the 820,000 kg of payload must consist of 260,760 kg. This leaves 559,240 kg of payload and structure.

Three flights per day of this magnitude, supports 750,000 persons on the moon!