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Another week has gone and the contractor has given excuses for not being back, I am at the point of contacting a lawyer due to the delays as winter approaches, Still hoping that the contracted work will be accomplished as it will cost me less than trying to get the money out of the contractor.
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For SpaceNut re #351
Thanks for telling us of the delays... It's possibly too late now, but escrow is the proven way to deal with questionable contractors.
I've seen it used by a large corporation. The contractor wanted money up front, and the corporation wanted to see the finished software product. What they agreed upon was an escrow account. The contractor could see the money, but it wasn't released until the work was done.
This may not be the only contractor you hire, so this might be an expensive learning opportunity.
PS ... the attorney's fees come out of the judgement against the plaintiff.
***
I logged in just now to report on testing of the Google Meeting system,
No camera found ... this happens after i use the system with another meeting package.
I'll have to restart the browser...
OK! Browser restart fixed the problem.
The waiting room will open at just before midnight UTC.
Now is 22:26 UTC
That will be 7 PM Houston and 8 PM New Hampshire
If PhotonBytes ever decides to join it will be midmorning in Australia.
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The waiting room is open at 23:59:59
gw Johnson logged in but his internet connection went down a few minutes later.
Weather is calm in Waco to it isn't weather.
gw was able to reconnect and we covered a number of topics. Along the way, GW showed me the Merlin Engine image in Wikipedia. I was struck by how closely it resembles the Merlin engine model we are using in the OpenFOAM topic.
I can easily imagine the original builder of the model tracing the outline of the engine from an image like the one in Wikipedia.
The shape is almost identical. The dimensions of the model may be different from the dimensions of the actual engine.
GW will continue looking for details. He did find what looks like the diameter of the throat.
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It is Google Meeting day once again for NewMars members !!!
The Waiting Room will open at midnight UTC as usual. 7 PM Houston 8 PM New Hampshire Mid-Morning in Australia
The link to join is provided in Post #1 of this topic.
I'm not expecting a huge attendance today! We have two members involved heavily in house projects.
That said, we someone who has not yet connected would be willing to give it a try, we've gained some experience using Google Meeting tools to take deep dives into the Internet investigating various technical issues that members bring up.
Starship has another launch coming up shortly.
Dream Chaser is postponed to 2026 at the earliest.
NASA appears to be hoping to achieve at least the Moon Circle flight with Artemis.
China is quietly massing experience with their space station. They have avoided losing a single Taikonaut.
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Systems check at 23:33 went well.
We have a successful run of the OpenFOAM project after a series of failures using a high performance solver called shockFluid.
In the end, we tried an easy going solver named rhoPimpleFoam, and managed to get through a run of .01 seconds without a crash.
We'll have something to look at this evening, if there is time and interest.
Otherwise we can discuss the orbit of the Moon which has such an influence on the living creatures of Earth.
For some reason I was totally unaware of the range of intervals between the appearance of the moon on one day and it's comparable appearance the next.
We have a starship flight coming up.
Other space launch entities have been busy.
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We're off to a good start!
kbd512 is back online after a very busy time.
GW Johnson is with us from McGregor Texas, with bright afternoon sunshine showing through the porch sliding door windows.
We started out with discussion of GW's sale of a VW bus to an enthusiast who is planning to put it back into operation.
That led to (to me surprising) discussion of how the original VW engine design has continued into the present day. Even the Chevrolet Corvair engines have persisted into the present day.
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Today is Google Meeting day for NewMars..
GW Johnson has a new study to show ... this one is on Moon landing, including access to the poles
Work on the extendedMerlin has made some progress...
We'll have animation to show of a successful 9 hour run showing hydrogen flowing through the entire system at 300 Kelvin.
Next week, this demonstration at 300 Kelvin will be followed by addition of (carefully designed) draining of the initial stash of hydrogen. The first time we tried this the hydrogen drained before the new addition arrived and the equation solvers went bonkers. The new strategy is to wait to begin draining until hydrogen is showing up at the nozzle after the long trip through the heat pipe.
Today's animation will clearly show the effect of drag on the plume of new hydrogen as it exits the nozzle ... the part of the plume that retains pressure greater than 1 bar is able to exit through the existing outlet, but the part that was slowed by drag stays in the engine compartment and circulates to cause turbulence which slows down processing due to the extra machine cycles needed to compute the flows. On the other hand, it ** is ** interesting to see vortex forming and moving around in the compartment.
The Real Universe test equipment would not have this problem if it were run in vacuum. The simulation cannot start out with vacuum conditions because the equations need enough mass to chew on, but simulating sea level conditions ** is ** achievable, so we've implemented that solution. A test article ** could ** be run at sea level, so the simulation's predictions would (presumably) come close to matching reality.
Today's demonstration will (hopefully) include showing how graphs can be generated from the data. I'm just beginning to learn about this capability, so only have one graph to show at this point. It shows how pressure varies due to the turbulence reported earlier.
All are welcome. The link to join the meeting is provided in Post 1 of this topic.
Each meeting features at least one deep dive into the Internet, led by kbd512, when he is able to attend.
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System check at 20:00:00 UTC went well...
We'll be back here in an hour.
All are welcome. Just use the link in post 1 of this topic.
The Waiting room is open at 23:59:23
*** That was another interesting meeting.
kbd512 was in fine form this evening! We started out with a deep dive based upon his recent post about masers.
In the midst of that, GW Johnson arrived, so we discussed how maser technology might help with SPS.
About midway through the evening, we branched into review of GW''s most recent paper on return to the Moon, using systems of his design based upon the successful Centaur hydrogen/LOX vehicle.
We wrapped up the hour with a brief review of the status of the extendedMerlin OpenFOAM study, with review of the results of the recent successful 9 hour run with pure hydrogen at 300 Kelvin. The run showed that we seem to have the model functioning well enough to not crash, but it did consume far more machine cycles than necessary due to a misconfiguration of the outlet panel. That misconfiguration was by design. Outlet to vacuum caused the run to crash, because unlike Ma Nature, OpenFOAM equations need some mass to chew on, and when we exhaust the gas to vacuum too early, the equations chomp on nothing and complain. the next run will start in a few minutes. It will run for 9 hours or so, with the outlet ramping up gently towards vacuum in increments designed to match the input of hydrogen at the intake. We can see that the intake settings are working well, because the hydrogen reaches the engine compartment and swirls around there. Here are some images of the successful 9 hour model.
<< images go here>>
The pressure display shows the arriving hydrogen backed up while trying to push through the nozzle:
http://40.75.112.55/phpBB3/download/file.php?id=45
The temperature display shows gas swirling around in the engine compartment. Temperatures are near 300 Kelvin, but excursions above occur because energy is added to the system by the arrival of fresh hydrogen gas from the intake pipe:
http://40.75.112.55/phpBB3/download/file.php?id=46
The Velocity display is the most interesting. It clearly shows the consequence of configuring the back wall (on the right) to only pass gas that has a pressure greater than one bar. Because gas is slowed on it's way to the back wall from the nozzle, it loses pressure and thus cannot exit, so it bounces back and causes turbulence. the next run will ease the congestion by ramping down the back wall slowly toward vacuum but stopping well shy of vacuum.
http://40.75.112.55/phpBB3/download/file.php?id=47
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Today is Google Meeting day for NewMars...
GW Johnson has completed and posted a study on return to the Moon.
kbd512 has posted about spacesuit materials in a new topic by RobertDyck
SpaceX completed their last Starship test flight with apparent success in all aspects.
SpaceNut has reported on scrambling to beat the Chinese back to the Moon, including letting go of the SLS boondoggle.
The extendedMerlin test program has advanced to heating hydrogen from earlier cold hydrogen runs.
SpaceNut has begun annotating the Daily Recap.
Other topics are likely.
All are welcome. The time is midnight UTC, 7 PM Houston, 8 PM New Hampshire, mid-Morning in Australia.
The link is published in post #1 of this topic.
***
Update: We may be joined by a student working with Blender.
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Systems check went well at 22:55 UTC.
The waiting room will open shortly before midnight.
the extendedMerlin run #25 just ended with some encouraging results to show. The run lasted 33 hours to cover 1 second of simulation time, starting from 0.
We have not yet reached full ramp up of the hydrogen intake. That will happen at two seconds. I'm hoping the results will look the same after 2 seconds, with possible increase in output velocity. ChatGPT5 tells me that ParaView may be showing incorrect colors if there was a hot spot somewhere in the mesh, but I'm looking forward to showing what we have, regardless.
Update: Waiting room is open at 23:58
This was another interesting and productive meeting. Topics included GW Johnson's recent work and kbd512's reporting on use of Gallium as a catalyst to separate Carbon and Oxygen in what appears to be a mechanical process of some kind.
The ParaView viewer was activated to look at the latest run of extendedMerlin.... I'll post images tomorrow. I am greatly encouraged by the results so far, but we are only 1 second into the run and need to reach 3 seconds to be sure we have a reliable system. We have only ramped up input half way, and we need to get to 2 seconds to see that.
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Today is Google Meeting Day for NewMars!
We have interesting new posts by Void and Calliban to discuss, along with the usual progress reports from GW Johnson.
The OpenFOAM series of runs finished overnight, so we will have animation to study covering the first 3 seconds of operation using the full flow of 2 kg/s of hydrogen, and application of 40 MW of solar power. At this point, it may turn out that the physics of heating gas passing by hot plates must be taken into account. Our mission to this point has been to try to get the simulation to work at all.
In addition, there is activity on the Robot Education front ...
We have a Lynxmotion device to study, as well as a similar (but very different) robot arm from cokoino.com.
In addition, kbd512 and I may have a few minutes to work on porting of the phpBB3 image supply software from Azure to the Mars Society servers. In the past week, spammers found the Azure account and effectively took it down by generating so many logon attempts that the logs filled up the available disk space. Our image server is currently offline.
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The systems check at 23:24 was a good idea. My new head set didn't work so I've re-installed the old wired one.
There isn't time to trouble shoot.
Other than that, everything appears to be working well for tonight's meeting.
The Waiting Room is open ...
This is an image uploaded by kbd512 to show how the phpBB3 site worksl
http://40.75.112.55/phpBB3/download/file.php?id=62
Update after the meeting:
Two topics received the bulk of attention today...
The proposed move of the image storage system from Azure to Mars Society servers appears to be feasible. kbd512 was able to upload an image to the Azure site after I brought it back online. The phpBB 3.3 server should install on the Mars Society server, in a directory tentatively called myimages.
If all goes well, our members will be able to access the site using newmars.com/myimages
Part of the procedure to port the application will be to backup the existing database and restore it into the Mars Society context.
Since the database is tiny, the port should go smoothly.
***
We also looked at the results of the 3 second run. While GW Johnson was not able to join us this evening, kbd512 made some educated guesses about the performance of the system. He proposed that the engine should be revised for hydrogen. It is designed for heavier molecules, and a nozzle designed for hydrogen would have a distinctively different shape.
I am delighted to have succeeded (with the help of ChatGPT4o and then ChatGPT5) in bringing the Merlin engine model to life with the extended heating tube and using hydrogen, despite the engine having been designed for completely different molecules. I'll attempt to post images from the 3 second run shortly.
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Today is Google Meeting Day for NewMars...
The Daylight Savings time has dropped back one hour in the US so the meeting time is no longer at midnight UTC.
The new UTC time is 1:00 ... That is ** really ** late for our European members, so I'm not expecting anyone to join from Europe.
This is a good moment to extend the invitation to hold a Google Meeting at a time more convenient for our European members.
As things stand, the Waiting Room will open a few moments before 1:00 UTC, 7 PM Houston, 8 PM New Hampshire.
It will be mid-morning in Australia.
GW Johnson has prepared a study of high speed flight, in addition to other papers he has published in recent weeks.
The recent OpenFOAM run to 3 seconds is available for discussion. I would like to know how to direct further study of the extendedMerlin model. It seems to me likely that there might be room for improvement of:
1) Measurement of Thrust
2) Increase of turbulence to improve heating
3) Increase of heating area in the heating tube
4) Geometry of the nozzle. The nozzle was designed for RP4 and LOX, not hydrogen and a much greater mass flow.
5) Other?
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Systems check was performed early today. Another online meeting was scheduled. This is the third event for the day.
Google Meeting is getting a workout.
I'm still trying to adjust to the time change. It is 17:20 New Hampshire time. 22:20 UTC ...
the meeting is set for 20:00 New Hampshire time so 2:40 from now. 22:20 + 2:40 is 24+60 >> 1:00 UTC
Update at UTC 00:48:49 ... setting up for tonight's meeting...
https://satcatalog.s3.amazonaws.com/com … 0710010020
Page 29 ...; Throat size 5.16 mm ... curve is conical ...
Throat radius .... curvature of throat ... efficiency of nozzle independent of gas ...
Reference: NASA page on rocket design ...
Throat curvature radius divided the diameter should close to one
https://rocketisp.readthedocs.io/en/lat … e_eff.html
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This was another interesting and productive meeting!
GW Johnson and kbd512 were in top form as we dealt with multiple topics....
We opened with the extendedMerlin engine model, and looked at results from the run to 3 seconds.
We transitioned to discussion of how to create a model for the rocket that is closer to what we need for the Optical Plane vessel.
The information about that is posted in Post #364
We looked at a paper GW wrote recently about building a Roman style platform on the Moon that would be strong enough to hold a Starship on it's spindly legs with their small pads.
In the course of that discussion, kbd512 reminded us of his many posts on sulfacrete, which is even called Marscrete because it is a possibility for Mars, where water will be in short supply.
Here is a search string that we put into Google:
sulfur mars concrete
To see the original properly formatted text, please use the Google Search string above.
"Sulfur Mars concrete" refers to a type of concrete called Marscrete, a waterless material for construction on Mars made from sulfur and Martian regolith (soil). It is being developed as an alternative to traditional concrete, which would be difficult to transport to Mars. While sulfur is abundant on Mars, it exists as sulfates and sulfides, not the elemental form needed for concrete, so a process is required to extract it first. How it works Binder: Molten sulfur is used as a binder, similar to how traditional concrete uses cement.Aggregate: Martian regolith is used as the aggregate, the sand-like material that makes up the bulk of the concrete.Production: The mixture is created by melting sulfur and mixing it with regolith, then letting it cool to harden. This process is energy-efficient because sulfur melts at a low temperature (\(~120^{\circ }C\)).3D Printing: The material is particularly suited for 3D printing, as it can be extruded as a viscous slurry and then solidifies as it cools.Recycling: Marscrete can be recycled by melting the sulfur again, allowing the concrete to be reused. Advantages for Mars Abundant materials: Both sulfur and regolith are readily available on Mars.Waterless: It does not require water, which is scarce on Mars.Strong: It can have a compressive strength of over 50 MPa, which is about twice as strong as conventional concrete.Fast-setting: It hardens quickly once cooled.Environmentally suited: The Martian atmosphere is dry and the temperature range is suitable for the material's properties. Challenges Elemental sulfur: Elemental sulfur is not found naturally on Mars, so it must be extracted from sulfur-containing minerals like sulfates and sulfides through an in-situ resource utilization (ISRU) process first.Shrinking: Sulfur concrete can shrink at Mars' low temperatures, which could cause cracking.Sublimation: In a vacuum, sulfur can turn directly from a solid into a gas, although this may be mitigated by the Martian atmosphere.Modification for 3D printing: The material does not hold its form well immediately after printing, requiring the addition of additives like polyethylene fibers to maintain shape during the printing process. 3D printed sulfur-regolith concrete performance evaluation for ...Sulfur concrete (SC), on the other hand, is a waterless alternative material that seems to be well-suited for planetary constructi...ScienceDirect.comMarscrete: A Martian Concrete for Additive Construction Applications Utilizing In Situ Resources | Proceedings | Vol , NoApr 14, 2021 — Marscrete is a Martian concrete material that is being developed at Northwestern University. It is the Martian version...ASCE LibraryMaterials Scientists Make Martian Concrete - MIT Technology ReviewJan 4, 2016 — By comparison, residential building standards on Earth require concrete with a compressive strength of about 20 MPa. Wa...MIT Technology ReviewShow all3D printed sulfur-regolith concrete performance evaluation for ...Sulfur concrete (SC), on the other hand, is a waterless alternative material that seems to be well-suited for planetary constructi...ScienceDirect.comMarscrete: A Martian Concrete for Additive Construction Applications Utilizing In Situ Resources | Proceedings | Vol , NoApr 14, 2021 — Marscrete is a Martian concrete material that is being developed at Northwestern University. It is the Martian version...ASCE LibraryMaterials Scientists Make Martian Concrete - MIT Technology ReviewJan 4, 2016 — By comparison, residential building standards on Earth require concrete with a compressive strength of about 20 MPa. Wa...MIT Technology ReviewMars: Readily usable sulfur for sulfur concrete?Feb 24, 2016 — Sulfur concrete is a mix of sulfur and aggregates that make a strong, quick-hardening concrete that is likely to be us...Space Exploration Stack ExchangeObtaining elemental sulfur for Martian sulfur concreteMar 4, 2022 — Sulfur is abundantly available on Mars, usually as sulfates, and, to a lesser extent, as sulfides. Unfortunately, eleme...Sage JournalsObtaining elemental sulfur for Martian sulfur concrete - ResearchGateSulfur on Mars, however, exists not as elemental sulfur—which is needed in concrete production—but as sulfates (usually hydrated) ...ResearchGateMartian Material Sourcing Challenges Propel Earth Construction ...Sep 3, 2019 — 3D Printing. Marscrete is especially well-suited for large-scale infrastructure 3D-printing (additive manufacturing) ap...ScienceDirect.comSulfur concrete as a construction material on MarsResearchers from Northwestern University have developed a structural material, called sulfur concrete, that is based entirely on r...www.accessscience.comMechanical behaviour of sulphur-based Martian regolith ...Jul 14, 2024 — 4. Conclusions * Sulphur is a very promising binder material to be used with Martian regolith as it becomes molten at ...ScienceDirect.comA novel material for in situ construction on Mars - ScienceDirect.comAug 31, 2016 — Highlights * • The developed Martian Concrete is highly feasible for construction on Mars. * The optimal Martian Concr...ScienceDirect.comSulphur Concrete - MarspediaOct 15, 2024 — Sulfur-regolith concrete is a waterless concrete that can be produced using sulfur and regolith. It has been found to ...Marspedia.orgPouring a Foundation on Mars - The New York TimesJan 10, 2016 — Researchers at Northwestern University have proposed a type of concrete that can be made from materials on Mars. The c...The New York TimesScientists develop Martian concrete for building architecture in outer spaceJan 6, 2016 — The concrete is a good choice for building on Mars because of the dry environment, atmospheric pressure, and temperatur...Dezeen Dive deeper in AI ModeAI responses may include mistakes. Learn moreCopy textSave to Google DriveWhen you export, you will allow Google Search to save AI-powered information to your Google Drive.Got itSave to GmailWhen you export, you will allow Google Search to save AI-powered information to your Gmail.Got itSave to Google DriveWhen you export, you will allow Google Search to save AI-powered information in a Colab notebook to your Google Drive.Got itDraft in GmailGoogle DocsExportPositive feedbackNegative feedbackThank you
Madras' XTEM develops waterless concrete for Mars using sulfur, builds microgravity drop tower, and explores space-based manufacturing.
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Today is Google meeting day for NewMars...
We've adjusted to the new UTC time of 1 AM, while holding steady to 7 PM Houston, 8 PM New Hampshire, and mid-Morning Australia.
GW Johnson has new papers for us to review.
The extendedMerlin model appears to have reached a stable thrust at 4 seconds into the run. We have the opportunity to discuss a concept for a flat heating system, and design of the hydrogen engine.
phpBB3 service on Azure will expire November 15th. There is a chance we may be able to port the image service to Mars Society servers..
Other topics are sure to come up. Among these might be the NSS meeting Saturday, which featured a speaker on the recent Mars Society Convention.
Systems check at 23:04 went well. We are on track to open the waiting room at 1:00 UtC, 7 PM Houston, 8 PM New Hampshire and mid-Morning Australia.
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The waiting room is open at UTC 00:56:05
Standing by for another interesting discussion...
https://www.mdpi.com/2226-4310/11/9/714
The link above points to one of the documents discovered by kbd512 in his ongoing and never ceasing research.
This one is about a design for a resistance heated propulsion system. The key information for study is the method of heating hydrogen gas via convection in turbulent conditions to insure optimum distribution of thermal energy to the gas.
We have a very similar problem to solve, with the additional complication of having to heat the convective framework with photons.
It is not at ALL clear what dimensions are best for this application. All we know for sure is that we are constrained to a distance of 240 meters to heat the hydrogen we are admitting to the heating system, and the flow is 2 kg/s distributed among however many heating pipes we end up with.
The meeting this evening covered a number of topics as usual, with emphasis on ongoing work with the Optical Plane vessel.
kbd512 and GW Johnson hammered out a concurrence on specifications for a rocket engine that I will pass along to a relative who is studying Blender, in hopes the relative might create an STL file of the engine that I can convert into an OpenFOAM mesh. The OpenFOAM model we have is of an engine designed for use at sea level with RP4 and LOX, and the engine we need would operate ONLY in vacuum with hydrogen as propellant.
The specifications for the design call for (as I remember them):
1) Throat diameter 2.5 cm
2) Bell diameter 25 cm
3) Computed length of the expansion bell (about 42 cm)
4) Shape for throat: torus
5) Shape for expansion bell: cone
6) Shape for intake of flow from heating system: flattened funnel (eg, 40 cm down to 2.5 cm in Y direction)
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tahanson43206,
Assuming I did this correctly, which I may not have since it's been about 20 years since I took trig...
For a 200:1 expansion ratio, given Athroat = 2.5cm^2 Athroat, then Aexit = 500cm^2.
r = sqrt(A/pi)
sqrt(2.5cm^2/pi) = ~1.772cm
sqrt(500cm^2/pi) = ~12.616cm
GW said keep the nozzle wall angle between 12 and 15 degrees to minimize erosion, so I'm going with 15 degrees:
base * tan(90-15) = height
12.616 * tan(75) = 47.084cm
1.772 * tan(75) = 6.613cm
47.084cm - 6.613cm = 40.471cm = height of the frustum (nozzle length)
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tahanson43206,
You asked about the thermal analysis for the core, so let's start with this NTRS document from 2016 related to recent work done by NASA on their new "small engine" NTR concept:
Thermal Hydraulics Design and Analysis Methodology for a Solid-Core Nuclear Thermal Rocket Engine Thrust Chamber
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tahanson43206,
This document from Idaho National Laboratory describes XNR-2000's conceptual design:
Conceptual Design of a CERMET NTR Fission Core Using Multiphysics Modeling Techniques
It describes materials that were actually tested and proven to survive 3,000K temperatures while exposed to hot flowing Hydrogen. The total Hydrogen mass flow rate required to achieve a 25,000lbf thrust level, with an Isp of 950s using 512MWth of reactor power output, was 12.05kg/s. At the exhaust temperature / velocity associated with a 950s Isp, we'd therefore need 45,150,618Wth of input power per 1,000kg-f.
Edit:
The exact dimensions of a reactor will effect the magnitude of the volumetric energy deposition profile within the fission core; however the basic geometry is still the same. As an initiating point, the geometry of a slightly modified XNR-2000 reactor concept was chosen as a baseline. The XNR-2000 reactor design consists of 151 fuel elements, each with 37 coolant channels with a radius of 0.1778 cm and lined with a 0.025 cm thick W-25%Re cladding tube. The modified XNR-2000 core had a coolant channel surface area to fueled volume ratio of 7.0189. Each fuel element was surrounded with a 0.025 cm thick tungsten cladding sleeve. The reactor has a length of 90.69 cm and was surrounded by a 16.45 cm thick beryllium neutron reflector...
This idea that the core heating length needs to be kilometers long is completely bogus. I have no clue where it comes from.
Let's tally the total coolant flow channel volume.
0.1778cm^2 * pi * 90.69cm = 9.006847cm^3
9.006847cm^3 * 37 channels per fuel element = 333.253339cm^3
333.253339cm^3 * 151 fuel elements = 50,321.254189cm^3 (about 0.05m^3)
50,321.254189cm^3 / 12.05kg/s = 4,176.037692cm^3 per 1kg/s
The above is not exact since there's a power density difference in different core regions, but it's close enough.
50,321.254189cm^3 / 512MWth = 98.2837cm^3 to transfer 1MWth
1kg/s produces 941.064kg-f, so 1.063kg/s produces 1,000kg-f at 950s.
Let's say we did use a singular tube to transfer core thermal power, for whatever good that would do for us:
151 fuel rods * 37 coolant channels per fuel rod * 90.69cm core length = 506,685.03cm
506,685.03cm / 12 = 42,223.7525cm = 422.237525m
If we had a mere 37 individual coolant channels to mimic a single fuel rod, then the length of each heat transfer tube is 11.412m. Presumably, we can manage a heat transfer tube length of 1m with 422 heat transfer tubes. If each tube was "touching", then the width of a planar heat transfer device is only 150cm across. Obviously we'd need spacing between tubes to contain the pressurized Hydrogen, but it's pretty easy to determine that a planar device with 422X 1m length heat transfer tubes is far less than 1m in width. If the thickness of this "hot plate" was 2X that of the tube diameter, then it's only 7.112mm thick. The device could be made from Tungsten and its total mass still wouldn't matter all that much to the performance of this low-thrust vehicle.
If we had a "hollow cylinder" (aka, "a pipe") device with a bunch of heat transfer pipes drilled through the pipe wall, with a gas manifold on each end, somewhat similar in external appearance to a NTR reactor core, but with a big empty space where the reactor fuel would normally go, then we ought to arrive at a mass / volume / length remarkably similar to an "empty" NTR reactor core (since our heat is being applied externally by concentrated sunlight, rather than generated internally through fissioning Uranium).
Last edited by kbd512 (2025-11-09 23:39:58)
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Thanks to kbd512 for Post 370, with data about a NERVA type propulsion system, including comparison to the current Optical Plane concept.
Today is Google Meeting day. I have invited guests but do not expect anyone to join the meeting, due to timing conflicts. If anyone ** does ** drop in for a visit they will be most welcome.
We are now opening the waiting room a few minutes before 1:00 UTC. That is a ridiculous time for our European members. On the other hand, it is 8 PM in New Hampshire, 7 PM in Houston and (I think) 6 PM in California and Washington. It is mid-Morning in Australia.
Topics we might pursue include:
1) The NERVA type reactor study reported by kbd512 in Post #370
I note the remarkable coincidence of radius of the heating tubes to the thickness of the OpenFOAM heating duct.
Todo item: Show thickness of model vs radius of tubes in study
From OpenFOAM topic: Z Range: -0.06303653966 to 0.06303653966 (0.126073 m)
The Z dimension for the existing Merlin engine model is 12.6 centimeters
For comparison: radius of 0.1778 cm from Post #370
Length of tube system: 422 meters from Post #370
For comparison, the length of the heating system for the Optical Plane vessel is 240 meters.
2) The transfer of our image server from the Azure test site to Mars Society servers
3) GW Johnson's latest paper on space station location (no surprise ... equatorial orbits win)
I have been able to allocate no time to the OpenFOAM heater update. Transition of the image server consumed all the free time I had. I have the heater update procedure saved in a document and hope to return to it next week.
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Systems check seemed to go normally at 23:25 UTC...
Waiting room is due to open at just before 1:00 UTC... 8 PM New Hampshire, 7 PM Houston, 6 PM for the Western states.
It will be mid-morning in Australia. I'd be astonished if anyone from Australia joins the call, but theoretically it ** could ** happen.
I'd be just about as surprised if anyone from Europe were to join in... But such a caller would certainly be welcome.
The waiting room is open at 00:59:38
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https://arc.aiaa.org/doi/10.2514/6.2011-5947
For GW and all> Link to article about CERMET nuclear rocket
Another link: https://www.osti.gov/biblio/1042399
https://ntrs.nasa.gov/api/citations/201 … 001802.pdf
From 2013 .... NASA
This is a duplicate copy of the link to the PDF that kbd512 found.
https://ntrs.nasa.gov/api/citations/201 … 001802.pdf
Above are notes from the Google Meeting of Sunday 2025/11/16
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INL removed the linked document in Post #370 from their website, or moved it, so here's an alternative link to the same document:
Conceptual design of a CERMET NTR fission core using multiphysics modeling techniques
Edit (in response to tahanson43206's question about the total number of coolant channels):
In this initial case, the fuel elements for both reactor configurations consisted of 37 coolant channels per fuel hex. Each reactor system was designed to have 6 lattice rows of fuel elements totaling 151 and the length of each reactor configuration was varied such that both systems had approximately the same drums out neutron multiplication number.
37 coolant channels per fuel element * 151 fuel elements = 5,587 coolant channels
Last edited by kbd512 (Yesterday 22:52:32)
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