Some proposals for low cost heavy lift launchers.

The announcement by two separate teams backed by highly regarded scientists and entrepreneurs for asteroidal or lunar mining means that quite likely there will be a significant market for super heavy lift. Note too that there were separate shuttle privatization plans with business models that involved privately investing perhaps $2 billion to produce a "shuttle 2.0". Quite key here though is a vehicle this size could serve as a super HLV without the ca. 80 mT shuttle orbiter.
I think at this point it is abundantly clear NASA can not be expected to make a cost effective launcher. An internal NASA estimate put the total development and launch cost of just four of the interim 70 mT SLS vehicles as $41 billion, which amounts to over $10 billion per launch.
SpaceX has shown by using good cost-saving business practices to be able to produce a launcher at greatly reduced costs. They estimate their upcoming Falcon Heavy will break the $1,000 per pound barrier, or $2,000 per kg. Keep in mind then that increasing the size of your launcher is supposed to reduce your per kg costs. So likewise using good business practices, a super heavy lift launcher privately developed should be able to at least match this or exceed it. This would be in the range of $200 million per launch for a ca. 100 mT launcher, a radically reduced cost over that of the SLS.
I think consideration should also be given to an all liquid system. You would use the DIRECT team's Jupiter HLV hydrogen-fueled upper stage but instead of using the shuttle ET for the first stage to hold hydrolox, use the same sized tank for kerolox. This would give a super heavy lift vehicle without the SRB's.
The DIRECT team wanted to use the same size tank to save on costs since you can use the same existing tooling in this case. However, a key fact is this will still be the case even if you switch to kerolox propellant. You would have to change the location of the divider between the fuel and oxidizer of course, but this is comparatively low cost compared to producing whole new tooling for a different size tank.
Now kerolox is a denser propellant so you are going to get a higher propellant load in this case. The density is about 3 times that of hydrolox, so lets say the propellant load of the first stage is now 2,100 mT. What about the dry mass?
At this point I think we should take note of the lightweight characteristics of the Falcon 9 that SpaceX was able to achieve. SpaceX has said the first stage of the Falcon 9 has a mass ratio better than 20 to 1. SpaceX did this by using well known techniques such as a common bulkhead design for the tanks. So we could follow this also to minimize first stage dry mass.
Also, note that by scaling our propellant tanks up, we actually improve our mass ratio. So likely we can get an even better mass ratio than this for our large first stage. But using the 20 to 1 figure, or 19 to 1 for propellant to dry mass ratio, we get a dry mass of 110 mT.
We need heavy thrust kerosene engines. I'll use the RD-171, with a sea level thrust of about 1,700,000 lbs, and vacuum Isp of 337 s. This will require 4 of the engines. This could be replaced later with the F-1 but using the RD-171 would allow you to start now on the vehicle development with better performance.
For the specifications of the upper stage, the DIRECT team went through several versions of their Jupiter super heavy lift vehicle. I'll use the one they referred to as Jupiter-246 Heavy, LV 41.5004.08001. For whatever reason, the DIRECT team no longer has the specifications for their vehicles up on their web site. This version's specifications are within this post to the SpaceFellowship.com forum:

An SSTO as "God and Robert Heinlein intended".
Posted on: Sat Mar 12, 2011 9:49 pm
http://spacefellowship.com/Forum/vie...52c48d6#p44979

though you'll have to register on that forum to view it.
This version used a propellant mass of 190,849 kg, a dry mass of 11,825 kg and 6 of the RL-10B2 engines, with an Isp of 459 s. Other versions have used the new J-2X engine, but just 6 RL-10's are likely to be cheaper.
This version's interstage and payload fairing were at about 4,000 kg each. We'll round off the upper stage propellant mass to 190 mT and dry mass to 11 mT. Then using a 9,150 m/s delta-V to orbit we can estimate the payload to orbit as 145 mT:

337*9.81ln(1+2100/(110+201+4+4+145)) + 459*9.81ln(1+190/(11+4+145))=9,176 m/s

Admittedly, this payload estimate seems high so I plugged some numbers into John Schilling's "Launch Vehicle Performance Calculator" and got:

Mission Performance:Launch Vehicle: User-Defined Launch Vehicle
Launch Site: Cape Canaveral / KSC
Destination Orbit: 185 x 185 km, 28 deg
Estimated Payload: 102573 kg
95% Confidence Interval: 86317 - 121993 kg

So it's still, likely, ca. 100 mT.

There are several variations on this theme. For example to save on development costs we could use the Ariane 5 core stage as the upper stage. Since the ESA was amenable to using it for an upper stage for a re-booted Ares I, i.e., ATK's "Liberty" rocket, they would likely be amenable to this as well.. You could also make this be parallel staging with cross feed fueling to improve performance.
Another possibility would be to make the upper stage also be kerosene-fueled. Say you used the same light-weight tooling and tank diameter for the hydrogen fueled upper stage but using now kerolox propellant. Again, you could improve performance by making it parallel staged with cross-feed fueling. But this has an additional advantage in that you could take one of the engines off the first stage to use it for the upper stage. This would result in a lower dry weight for the first stage. The upper stage though would then be somewhat overpowered using a RD-171, so it may suffice instead to use a RD-180 just for the upper stage.



Bob Clark

In article 13663420.135.1335884487613.JavaMail.geo-discussion-
forums@vbfg3, says...

The announcement by two separate teams backed by highly regarded
scientists and entrepreneurs for asteroidal or lunar mining means
that quite likely there will be a significant market for super
heavy lift.

Why would this require heavy lift? The requirement is to return large
amounts of (valuable) materials to earth, not launch large amounts of
material from earth. This is especially true if you use in-situ fuel
production on a relatively small asteroid (small gravity well). In
order to make such a venture profitable, it would be very nice to lower
launch costs (per pound of payload) but that doesn't require heavy lift
either.

Even better is to keep as much of the transportation infrastructure in
space as you possibly can. Eliminating as many trips out of earth's
gravity well reduces costs without requiring larger or more frequent
launches.

SpaceX has shown by using good cost-saving business practices
to be able to produce a launcher at greatly reduced costs. They
estimate their upcoming Falcon Heavy will break the $1,000 per
pound barrier, or $2,000 per kg. Keep in mind then that
increasing the size of your launcher is supposed to reduce your
per kg costs. So likewise using good business practices, a
super heavy lift launcher privately developed should be able to
at least match this or exceed it. This would be in the range of
$200 million per launch for a ca. 100 mT launcher, a radically
reduced cost over that of the SLS.

There are limits when growing a system like this. When your super large
vehicle only flies a few times a year, you're still paying the "standing
army" to do nothing while they wait for the next super large payload to
launch. Saturn V and the space shuttle both suffered from the "standing
army" problem.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

"Jeff Findley" wrote in message
...

In article 13663420.135.1335884487613.JavaMail.geo-discussion-
forums@vbfg3, says...

The announcement by two separate teams backed by highly regarded
scientists and entrepreneurs for asteroidal or lunar mining means
that quite likely there will be a significant market for super
heavy lift.

Why would this require heavy lift? The requirement is to return large
amounts of (valuable) materials to earth, not launch large amounts of
material from earth. This is especially true if you use in-situ fuel
production on a relatively small asteroid (small gravity well). In
order to make such a venture profitable, it would be very nice to lower
launch costs (per pound of payload) but that doesn't require heavy lift
either.


The more I think about it, the more I think the biggest two problems will
be:

1) the environmental impact statement. Right now there's not enough need in
orbit for materials (other than possibly volatiles). But I can't really see
the "Ok, we're going to dump X tons of copper and rare-earths in your
backyard" going over well (and do you dump one large mass or many little
ones!)

2) market collapse. I still can't see this working whre you can bring back
enough materials at current prices to make it worthwhile, w/o collapsing the
market. That said, I'd love to see the numbers.

Personally, I think the best option right now is a minimal mass mission to a
smaller asteroid and then using something like an ion drive to nudge it into
an Earth intersecting orbit and use aerobraking to dump it into a remote
area and using normal earth-bond equipment to break it up.


Jeff

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

In article ,
says...

"Jeff Findley" wrote in message
...

In article 13663420.135.1335884487613.JavaMail.geo-discussion-
forums@vbfg3, says...

The announcement by two separate teams backed by highly regarded
scientists and entrepreneurs for asteroidal or lunar mining means
that quite likely there will be a significant market for super
heavy lift.

Why would this require heavy lift? The requirement is to return large
amounts of (valuable) materials to earth, not launch large amounts of
material from earth. This is especially true if you use in-situ fuel
production on a relatively small asteroid (small gravity well). In
order to make such a venture profitable, it would be very nice to lower
launch costs (per pound of payload) but that doesn't require heavy lift
either.


The more I think about it, the more I think the biggest two problems will
be:

1) the environmental impact statement. Right now there's not enough need in
orbit for materials (other than possibly volatiles). But I can't really see
the "Ok, we're going to dump X tons of copper and rare-earths in your
backyard" going over well (and do you dump one large mass or many little
ones!)

2) market collapse. I still can't see this working whre you can bring back
enough materials at current prices to make it worthwhile, w/o collapsing the
market. That said, I'd love to see the numbers.

Personally, I think the best option right now is a minimal mass mission to a
smaller asteroid and then using something like an ion drive to nudge it into
an Earth intersecting orbit and use aerobraking to dump it into a remote
area and using normal earth-bond equipment to break it up.

Ion propulsion to get to the asteroid, but to get it back, you would
need to use propellants obtained from the asteroid. I'm not sure you'd
find suitable propellants, easily obtainable, for an ion engine on an
asteroid. Trying to launch enough ion propulsion mass from earth to do
the job would be economic suicide.

You might be better off with a solar powered engine using whatever
volatile reaction mass you can obtain from the asteroid.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker