Author Topic: If given a clean sheet of paper....  (Read 76936 times)

Offline Antares

  • ABO^2
  • Senior Member
  • *****
  • Posts: 5181
  • Done arguing with amateurs
  • Liked: 371
  • Likes Given: 225
Re: If given a clean sheet of paper....
« Reply #200 on: 09/30/2008 02:39 am »
History proved many times over that private businesses in competitive environment are better at designing, well, just about anything, than governments.
I wonder if you could provide a reference because history has taught me no such thing.
Atlas III, Delta IV, Atlas V, Falcon 1, vs Ares
the automotive industry, biotech,
any building you can name vs an equivalent bought by the government,
commercial imagery satellites vs FIA, personal computers vs ODIN
the response by churches and civic groups to natural disasters vs FEMA,
anything carried in an astronaut's personal kit to ISS vs when it's formally manifested,
Skunk Works vs MSFC, Windows, Mac,
airline scheduling systems vs FAA ATC modernization,
industrial control systems vs CLCS, any ELV control system vs CLCS.....

I'll refrain from a who-you-should-vote-for statement.
« Last Edit: 09/30/2008 02:43 am by Antares »
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 14711
  • Liked: 7171
  • Likes Given: 1146
Re: If given a clean sheet of paper....
« Reply #201 on: 09/30/2008 03:16 am »
History proved many times over that private businesses in competitive environment are better at designing, well, just about anything, than governments.
I wonder if you could provide a reference because history has taught me no such thing.
Atlas III, Delta IV, Atlas V, Falcon 1...

The first three were largely based on government funded developments, or are continuing to be propped up with government money.  SpaceX is spending government money too.  Neither EELV would exist without Pentagon money.

 - Ed Kyle

Offline Patchouli

  • Senior Member
  • *****
  • Posts: 4490
  • Liked: 252
  • Likes Given: 454
Re: If given a clean sheet of paper....
« Reply #202 on: 09/30/2008 05:57 am »

this would trade isp for mass fraction, ruggedness and re-usability.


Nitric acid would impede re usability savings

Nitric acid might be a poor choice for an RLV but it might be a great choice for a big dumb booster that is simple and cheap to produce vs reusable.

Though  Robert Truax did reuse a nitric acid oxidizer aerobee rocket a few times.

I think lox kerosene ,lox propane/methane, or tripropellant lox,kerosene, and hydrogen are better choices for RLVs.

Pure lox hydrogen RLVs seem to suffer from the tanks and thermo protection becoming too large of a mass fraction.
This ends up hurting the payload mass fraction as seen in the X33 unless it's an air breather like Skylon or makes the engines do double duty as the main heat shield like ROMBUS and the SASSTO.
« Last Edit: 09/30/2008 06:08 am by Patchouli »

Offline Antares

  • ABO^2
  • Senior Member
  • *****
  • Posts: 5181
  • Done arguing with amateurs
  • Liked: 371
  • Likes Given: 225
Re: If given a clean sheet of paper....
« Reply #203 on: 09/30/2008 09:09 pm »
History proved many times over that private businesses in competitive environment are better at designing, well, just about anything, than governments.
I wonder if you could provide a reference because history has taught me no such thing.
Atlas III, Delta IV, Atlas V, Falcon 1...
The first three were largely based on government funded developments, or are continuing to be propped up with government money.  SpaceX is spending government money too.  Neither EELV would exist without Pentagon money.

The question was about who did the design, not who funded it.  Inexperienced government designers and/or requirements creep will kill anything where the government doesn't let the private sector do its thing.  It's obvious that certain markets would not exist without government seed money, and some of those markets would not exist without government sustenance.  But the shortest route to a solution the private sector won't do on its own is for the government to decide what it wants, put up the money and then make sure the contractor stays on the road, not necessarily on the centreline.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline lewis886

  • Full Member
  • *
  • Posts: 171
    • OldFutures
  • Liked: 5
  • Likes Given: 1
Re: If given a clean sheet of paper....
« Reply #204 on: 10/04/2008 07:24 pm »
i thought about posting a new thread for this... but i guess this thread is similar enough...

let's say that the next president doesn't dismantle the Ares program right away... and we get a few years into it... and the shuttle is retired... all the shuttle infrastructure is done away with... and then the Ares 1 is found to be unworkable and is subsequently scrapped, and the Ares V is just too big and pricey to build (obviously)...  and NASA is left with a spacecraft (orion) with no launch vehicle...

So let's say that at that point, you stepped in as the NASA chief admin, and were tasked with building a versatile launch vehicle that would not compete with EELV, and would be capable of doing a lunar mission.... given the constraints of economy (possibly depressed at that point), and knowing the big companies that you have available to contract with.... what would you do?   what kind of launch vehicle would you design?

Direct is obviously a fantastic design right now... and is a great direction to go in for what we already have right now...  but this is supposing that we are a few years down the road... and we don't have the workforce/infrastructure/hardware associated with the shuttle anymore.... i remember Ross saying once that he didn't think that Direct was the best launch vehicle... it was just best for what we have to work with right now ....  so, Ross (and anyone else)... what WOULD you design if you weren't trying to work within the current shuttle framework?


EDIT:  and not just what "launch vehicle"... but what overall architecture too... (supposing the size/design of your launch vehicle is dependent on fuel depots, etc).

Yes, this is similar to much of the rest of this thread... but rememeber, YOU are the NASA admin in 2013 or so, no more shuttle architecture, and all the economic (no increase in nasa budget) and political forces to deal with...
« Last Edit: 10/04/2008 09:01 pm by lewis886 »

Offline EE Scott

  • Full Member
  • ****
  • Posts: 1166
  • Liked: 56
  • Likes Given: 274
Re: If given a clean sheet of paper....
« Reply #205 on: 10/04/2008 09:08 pm »
i thought about posting a new thread for this... but i guess this thread is similar enough...

let's say that the next president doesn't dismantle the Ares program right away... and we get a few years into it... and the shuttle is retired... all the shuttle infrastructure is done away with... and then the Ares 1 is found to be unworkable and is subsequently scrapped, and the Ares V is just too big and pricey to build (obviously)...  and NASA is left with a spacecraft (orion) with no launch vehicle...

So let's say that at that point, you stepped in as the NASA chief admin, and were tasked with building a versatile launch vehicle that would not compete with EELV, and would be capable of doing a lunar mission.... given the constraints of economy (possibly depressed at that point), and knowing the big companies that you have available to contract with.... what would you do?   what kind of launch vehicle would you design?

Direct is obviously a fantastic design right now... and is a great direction to go in for what we already have right now...  but this is supposing that we are a few years down the road... and we don't have the workforce/infrastructure/hardware associated with the shuttle anymore.... i remember Ross saying once that he didn't think that Direct was the best launch vehicle... it was just best for what we have to work with right now ....  so, Ross (and anyone else)... what WOULD you design if you weren't trying to work within the current shuttle framework?

I love these hypothetical questions.  This is the stuff I think about after drinking too much French Roast coffee - like right now.  I think at the point outlined above, we really only have the EELV assets or some of the designs that were nurtured briefly in the 90's by NASA (e.g., RS-84, RS-83, Fastrac, etc).  Sooooo....

"Datlas I" LV:  Take the current paper Atlas V 5x2 and replace the RD-180 with two RS-68A's.  Manrate the current Atlas SRBs and add them to the mix until Orion is liftable to ISS.  All H2 LV, crash program.  SRBs lower the LOM #?  That's what the LAS is for.  Just get on that rocket, sucka...

Even with flat or slightly decreased budgets, this can be done.

Begin development of a modernized Saturn V, call it the Datlas V if you want.  Seek to optimize support ops and economize construction and development costs.  One possible design:  six RD-180 first stage (US-made RD-180 if necessary), 4 or 5 J-2X second stage, third stage optimized as necessary (e.g., no 3rd stage?, 1 J-2X 3rd stage? etc.).  Take a look at re-doing the F-1A/RS-84 in place of RD-180 if you like (but that would greatly expand the development time frame).

So with the "Datlas I" LV one has a possible long-lived LEO LV that wouldn't compete with current EELVs (oh wait, maybe it would compete with D-IVH - Oh well).  Fund the Saturn V knock-off as budget allows within a 2 or 2.5 launch architecture (2.0 Datlas Vs), along with the other necessary components of the VSE.

There are so many variables to that scenario.  And perhaps my LVs wouldn't survive a good cost or POST analysis.  But it's fun to think about.

Edit:  My VSE *might* skip the moon and go for 1) exploration of NEO's, 2) with flyby's of Venus and Mars, just because I think it's important to push the envelope of man's exploration experience.  There is no substitute for being there.  If budgets are flat or going down, actually landing on Mars seems to be a bit too much to ask if we are also going to do unmanned space science and astronautics research (which we should).
« Last Edit: 10/04/2008 09:26 pm by EE Scott »
Scott

Offline guru

  • Full Member
  • ****
  • Posts: 483
  • Liked: 78
  • Likes Given: 33
Re: If given a clean sheet of paper....
« Reply #206 on: 10/04/2008 09:50 pm »
Fund upgrade to the Delta IV - 7 meter, 2 RS-68 core.  3 core vehicle with a new J-2X U/S could put 107 tonnes in LEO.  Launch from current shuttle pad locations, just with rebuilt pads.

Offline guru

  • Full Member
  • ****
  • Posts: 483
  • Liked: 78
  • Likes Given: 33
Re: If given a clean sheet of paper....
« Reply #207 on: 10/04/2008 09:51 pm »
Otherwise, pretty much like the DIRECT architecture.  Propellant depots, Orion, Altair, etc.

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10505
  • Liked: 601
  • Likes Given: 24
Re: If given a clean sheet of paper....
« Reply #208 on: 10/04/2008 10:25 pm »
My personal preference for a clean sheet design hasn't changed much over the last few years.   If we're talking a design which can remain on a reasonable budget and be implemented in a realistic period of time, but that we also assume removing *all* SDLV influences entirely from the equation, deliberately choosing to ignore all the political aspects, the workforce issues etc., I'd do something like this:-

1) Turn Shuttle into Jupiter-120.   Second Choice: Human-rate the existing Delta-IV Heavy or make an HR Atlas-V Heavy - purely for flying Orion to ISS as soon as humanly possible for the least cash outlay.   Planned flights: 2 per year thru 2016, maybe 2020.   Use existing EELV pads and negotiate with DoD.

2) Develop Sea Dragon by 2020.

3) Develop a 200mT Lunar Lander by 2020.

4) Develop a high-performance nuclear in-space propulsion system by 2025.

5) Develop a 2-launch 900mT Mars Mission by 2030.

6) Plan 2- 3- or 4-launch (900mT, 1,350mT or 1,800mT) large-scale human missions to Europa, Titan and any other destination in the solar system which you care to mention beginning by 2035.

X) Launch ISS Mk II in a single launch whenever possible.   Then spend our time actually using it, not building it.

Job Done.

Ross.
« Last Edit: 10/05/2008 04:03 am by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 11606
  • Connecticut
    • Direct Launcher
  • Liked: 6095
  • Likes Given: 2984
Re: If given a clean sheet of paper....
« Reply #209 on: 10/04/2008 10:58 pm »
OT, but just a reminder that today is the anniversary of the launch of Sputnik-I, and the beginning of the space age; October 4, 1957.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline tankmodeler

  • Regular
  • Full Member
  • ****
  • Posts: 643
  • Brampton, ON, Canada
  • Liked: 6
  • Likes Given: 0
Re: If given a clean sheet of paper....
« Reply #210 on: 10/05/2008 03:42 am »
If starting with a clean sheet, first Id decide what the objective was to be. In my case, it would be a sustainable manned LEO architecture as a base for manned exploration of the solar system and commercial exploitation. NASAs emphasis would on the exploration of the solar system and commercial companies would be responsible for sustaining the LEO infrastructure.

The Moon would be used to test systems for Mars and also would be open for commercial access and resource development. On that basis a reasonably robust outpost system would be developed, again with NASA leading the way and developing the technology and corporations doing the sustaining once the path has been cleared.

So, that said, what kind of launchers would we need?
1)   EELVs to get basic infrastructure to orbit, support ISS & start the ball rolling.
2)   Dirt cheap fuel carriers to top up an orbital fuel depot. Commercial contracts let to the lowest bidder. Really cheap little boosters with acceptable failure rates in the 5% range. Unsuitable for cargo more valuable than fuel.
3)   Medium lift crew vehicle to tend the depot and any LEO infrastructure Commercial launcher in the 20 ton class and NASA crew vehicle, capsule first and reusable later on a larger booster if flight rates warrant. The 20 ton booster would be RP1/Lox on the first stage & H2/Lox for the second.
4)   Heavy lifter for exploration stages of lunar exploration. 90-100 ton class, commercially developed and optimised for low cost operation, a smaller Sea Dragon to prove the design concepts and to allow cargo to be lifted to the moon as cheaply as possible.
5)   Once the Moon is into the commercial phase, continued use of the little Sea Dragon and solar electric tugs to ferry stuff to the Moon.
6)   For the exploration phase of Mars, a full blown Sea Dragon in the 400 ton class. Past that the crystal ball gets murky, but commercial interests should be well positioned to do things like solar electric tugs to Mars & commercial bases on the surface, should there be a need for repeated trips.


Paul
Sr. Mech. Engineer
MDA

Offline Scotty

  • Member
  • Full Member
  • ****
  • Posts: 1213
  • Merritt Island, Florida
  • Liked: 1615
  • Likes Given: 0
Re: If given a clean sheet of paper....
« Reply #211 on: 10/05/2008 11:08 pm »
A clean sheet of paper;
First a new hydrocarbon 2 million pound thrust class booster engine, I like Lox/Methane, but LOX/RP1 would be ok.
Second a new LOX/Hydrogen 1 million pound thrust class engine for upper stage use.
Five or six of the new booster engines on the first stage, with two or three of the new upper stage engines on the second stage, with one of the new upper stage engines on the third stage/Earth Departure Stage.
The resulting booster should be good for at least 150 to 160 mT in LEO, and would still be small enough and more importantly be light enough, to be serviced by the existing KSC launch infrastructure.
If you really want to top the above, develope a 1/2 million pound thrust class NTP engine for the Earth Departure Stage, with a bi-modal reactor that could furnish power for a VASIMR cruise engine.
Can you say Mars in less than 90 days? Sure you can!

Offline gin455res

  • Full Member
  • ****
  • Posts: 491
  • bristol, uk
  • Liked: 40
  • Likes Given: 63
Re: If given a clean sheet of paper....
« Reply #212 on: 03/18/2009 08:07 pm »
Quote
nuclear thermal ammonia with lox afterburner. The reactor would not run very hot. The endothermic disassociation of the ammonia and moderate heating would add plenty of energy so the reactor wouldn't need to push the envelope thermally.  Or some other endothermic disassociation that supplies a hot stream of h2-rich fuel could be used e.g. a pressurized water-propane emulsion that is reformed to carbon monoxide and hydrogen. The nuclear thermal could be replaced with solar thermal, but this would be much lower thrust.
;-)

I once downloaded the isp rocket program that is on Bruce Dunn's website. I then changed the enthalpy of ammonia until it ended up dissociating at something like 1000c. This was to 'simulate' nuclear thermal heating. I then used this new  ammonia with oxygen and ended up getting isps of about 400.  Any idea if this could have been in any way valid?

Also, I just found an article:http://www.iasmirt.org/iasmirt-3/SMiRT10/DC_250636 describing the use of nitrogen tetroxide in brayton cycles. It shows how the disassociation of the n204 first to 2no2 and then to 2no + o2, which is endothermic, can reduce the size, and increase the efficiency of brayton cycle electric powerplants.

This makes me wonder if ammonia and n2o4 when heated by a nuclear reactor, because of their endothermic disassociation at fairly low temperatures, could make for a nice compromise between fully nuclear and fully chemical rocket propulsion.

Both these chemicals can absorb large amounts of energy at reasonably 'low' temperatures. So, can this be sensibly modelled by 'messing with their enthalpies' in that same isp program?

Any thoughts?

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10505
  • Liked: 601
  • Likes Given: 24
Re: If given a clean sheet of paper....
« Reply #213 on: 03/18/2009 09:14 pm »
A clean sheet of paper;
First a new hydrocarbon 2 million pound thrust class booster engine, I like Lox/Methane, but LOX/RP1 would be ok.
Second a new LOX/Hydrogen 1 million pound thrust class engine for upper stage use.
Five or six of the new booster engines on the first stage, with two or three of the new upper stage engines on the second stage, with one of the new upper stage engines on the third stage/Earth Departure Stage.
The resulting booster should be good for at least 150 to 160 mT in LEO, and would still be small enough and more importantly be light enough, to be serviced by the existing KSC launch infrastructure.
If you really want to top the above, develope a 1/2 million pound thrust class NTP engine for the Earth Departure Stage, with a bi-modal reactor that could furnish power for a VASIMR cruise engine.
Can you say Mars in less than 90 days? Sure you can!

I would strongly second that approach.

I would also put some money in to some other in-space propulsion technologies as well, not just VASIMR.   There are a variety which could all do with funding to see which is really better -- and the side effect of a lot of that research is that it would improve the US domestic knowledgebase for nuclear technologies, a field which is currently led by the French and the Japanese with the US lingering in a very pittiful position a long way down.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline marsavian

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 3216
  • Liked: 2
  • Likes Given: 3
Re: If given a clean sheet of paper....
« Reply #214 on: 03/18/2009 11:23 pm »
Heh, it seems all non SRB roads lead back to the three stage Saturn V engine/fuel combinations ;-)

Offline mmeijeri

  • Senior Member
  • *****
  • Posts: 7767
  • Martijn Meijering
  • NL
  • Liked: 387
  • Likes Given: 795
Re: If given a clean sheet of paper....
« Reply #215 on: 03/18/2009 11:35 pm »
Heh, it seems all non SRB roads lead back to the three stage Saturn V engine/fuel combinations ;-)

Very interesting indeed. And yet it's not just the Shuttle that uses solids. Some versions of the Atlas use them as well. Is that because of past or present political pressure or do they have real advantages in some cases? I remember reading that US ICBM's used solids at one point because they are even more storable than rockets using hypergolic fuels. Is that still the case?
Pro-tip: you don't have to be a jerk if someone doesn't agree with your theories

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 35960
  • Cape Canaveral Spaceport
  • Liked: 18337
  • Likes Given: 397
Re: If given a clean sheet of paper....
« Reply #216 on: 03/18/2009 11:45 pm »

1. Very interesting indeed. And yet it's not just the Shuttle that uses solids. Some versions of the Atlas use them as well.

2.  Is that because of past or present political pressure or do they have real advantages in some cases?

3.  I remember reading that US ICBM's used solids at one point because they are even more storable than rockets using hypergolic fuels. Is that still the case?

1.  not the same thing.  Atlas and Delta use them as augmentation, shuttle uses them as primary boosters

2.  No way.   Both were designed without them at the beginning.  Commercial comsats out grew the EELV medium class and it is easy to add solids to a vehicle as augmentation.

3. yes

« Last Edit: 03/18/2009 11:45 pm by Jim »

Offline mmeijeri

  • Senior Member
  • *****
  • Posts: 7767
  • Martijn Meijering
  • NL
  • Liked: 387
  • Likes Given: 795
Re: If given a clean sheet of paper....
« Reply #217 on: 03/18/2009 11:50 pm »
1.  not the same thing.  Atlas and Delta use them as augmentation, shuttle uses them as primary boosters

2.  No way.   Both were designed without them at the beginning.  Commercial comsats out grew the EELV medium class and it is easy to add solids to a vehicle as augmentation.

3. yes

So solids are not bad or outdated in and of themselves? They're just tools that are appropriate for certain applications and less so for others? And are the examples you mentioned examples of solids used appropriately?
Pro-tip: you don't have to be a jerk if someone doesn't agree with your theories

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 35960
  • Cape Canaveral Spaceport
  • Liked: 18337
  • Likes Given: 397
Re: If given a clean sheet of paper....
« Reply #218 on: 03/18/2009 11:53 pm »
Solids have their place.  They are great for weapons and simple applications

Offline DonEsteban

  • Member
  • Posts: 67
  • Liked: 0
  • Likes Given: 0
Re: If given a clean sheet of paper....rephrasing the question..
« Reply #219 on: 03/19/2009 01:07 pm »
Hm, what about going at it from the other side:

You are asked to deliver say 2000t per year, during at least five years, to LEO. The first delivery in 5 or 7 years from now.

The lowest bidder (with reasonable guarantees) gets the main contract, others get smaller contracts as well (say 100-500t per year).

What kind of system would get the lowest overall price?

Tags:
 

Advertisement NovaTech
Advertisement SkyTale Software GmbH
Advertisement Northrop Grumman
Advertisement
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1