kbd512 Postings

tahanson43206 · 2024-03-07 14:20:36

For kbd512 ... just a quick note to acknowledge your long post #25, and your recent contribution to the asteroid harvesting series. The bolo example is interesting, and I hope it generates some interest.

I just looked in on the Dropbox account, and we have two files there, both from 2023.

(th)

tahanson43206 · 2024-03-16 20:22:53

For kbd512 ....

Please see https://newmars.com/forums/viewtopic.ph … 68#p220468

I've set up an Azure account for the forum upgrade. If you can make tomorrow's Google meeting, we can (hopefully) try it out.

I created the account with a password that is designed with you in mind.

(th)

tahanson43206 · 2024-03-18 14:37:14

For kbd512 ...

My experiments with the plain Apache we set up were less than rewarding ...

Everything I tried ended up with a decline. I sent you an email with a few of the details.

The environment is MUCH less accommodating than the ** real ** Ubuntu.

I think it makes sense to remove that instance (if we can) and try to set up the LAMP.

I'll check back to see if you want to work on this again this evening or later this week.

(th)

kbd512 · 2024-03-18 18:31:10

Do you have time to work on the forums at 8PM CST?

If so, I'll be here.

tahanson43206 · 2024-03-18 18:54:30

For kbd512 re #29

I just finished some chores and found your message.

I'll set up the Google Meeting and try to have it ready by 9 PM my time. I might be a minute or two late.

(th)

kbd512 · 2024-03-18 18:59:35

Okay. I'll be there.

kbd512 · 2024-03-18 19:49:31

tahanson43206,

My modified copy of the FluxBB Master has been uploaded to DropBox. Please let me know if you're able to access the files.

tahanson43206 · 2024-03-18 20:12:32

For kbd512 re #32

Thanks for doing the upload! I pulled it down on the U64 where the database is already installed.

The file size shows as 380 kb ... file name is fluxbb-master.zip.

Does this go into the same folder/directory as the existing php files? I assume so but thought I'd check to be sure.

I vaguely recall that there is a pointer file in the apache2 chain that points to applications.

You saw the listtopic.php script running... it is installed in /var/www/html

There's a file called "require.php" located at the www level. OK ... that file provides access to the mysql database.

(th)

kbd512 · 2024-03-18 21:48:10

tahanson43206,

The extracted files from the ZIP archive file are to be deployed into the "htdocs" folder / directory (or whatever directory your setup is pointed at / named, since this is configurable) of your Apache Web Server's installation directory.

tahanson43206 · 2024-04-03 06:43:19

For kbd512 ...

Thank you for the detailed post about composite materials for rocket tanks compared to steel as used by SpaceX.

Here is a quote from your conclusion:

If I had to hazard a guess, Elon Musk (most likely) or someone else at SpaceX attempted to apply their observations about what happens to highly stressed COPVs at cryogenic temperatures to a CFRP main propellant tank that experiences nowhere near the stress of a CFRP COPV operated at the same temperature.

I'm wondering if you might be willing to add definitions of the abbreviations at the end of the document, for readers who might not be familiar with the subject?

It seems to me the overall point (in response to RGClark's questions) is made effectively.

In your conclusion, I confess to having lost track of the materials. I ** think ** the paragraph was comparing steel to composite, but am not sure.

***
Thanks for the guidance in #34 .... You have access to the test system in Azure, so you can set up the software properly there.

We have 12 days left in the free trial. Everything is working properly, as far as I can tell. The ssh command should work for you by just changing the IP address to the new value as published in the Azure topic.

The only wrinkle that may occur is authentication. Azure challenges me to provide a code from the newmarsmember gmail account when I use a different computer to access the system. If that happens I'll be happy to assist, but it may not because your computer may already have the hidden files that grant access.

(th)

tahanson43206 · 2024-04-08 21:04:15

For kbd512

SpaceNut found a link to a backup of the missing newmars front page: https://web.archive.org/web/20190522184 … wmars.com/

The 404 error is still there.

(th)

kbd512 · 2024-04-08 23:11:37

tahanson43206,

I have a copy of the page ready to go, if only I could log into the server.

tahanson43206 · 2024-04-09 06:06:45

For kbd512....

Thanks for the update.

Let's email to consider next step.

(th)

tahanson43206 · 2024-04-18 09:19:42

For kbd512 re post in Housekeeping!

Thanks for an excellent suggestion!

I'll schedule a work session to scan phpBB3 in the near future.

If I can fit it in today I'll do so, but I'll get to it Saturday for sure. Friday is booked.

I appreciate your support of phpBB3, because it is shaping up nicely in the Azure test account.

(th)

tahanson43206 · 2024-04-24 19:06:39

For kbd512 re Registration message....

SpaceNut tried to change the registration message using Admin tools, but apparently there is no option to edit the text.

The text is located in the register.php file.

(th)

tahanson43206 · 2024-05-11 09:22:39

For kbd512 re Steel for Trains post...

http://newmars.com/forums/viewtopic.php … 55#p222955

That post deserves recognition .. Thanks for collecting and showing all those examples of use of steel and coatings suitable for a Lunar railway.

Please start thinking about a Like feature we might add to the FluxBB package we are preparing for deployment.

What I have in mind would use the existing Integer Edited field in the Posts table. That field would be updated by a new class of membership, the LikePosts class, which would be offered to NewMars readers who do not want to move all the way to Registered membershipm, but would like to encourage NewMars authors.

The feature would require a new table with Post ID matched with User ID for a like, and only one "like" per post per user.

An Admin report would allow display of which users liked a given post.

(th)

tahanson43206 · 2024-05-12 06:21:38

For kbd512 re analysis and discussion of staging of rockets to reach orbit, and propulsion concepts in general, in the SSTO topic.

I'd like to see a mathematical treatment of the problem at some point, with visual aids for non-mathematicians.

I'll try to come up with a chart form that might work as a frame for NewMars members to use to come to grips with the problem.

The problem (as I understand it) is that there are multiple variables involved in design of a rocket system able to reach orbit in a given gravitational field.

The variables include:

1) Mass of each stage (dry mass)
2) Mass of propellant for each stage
3) ISP of propellant in each stage
4) Design of the rocket engine and related hardware

There may be other variables.

As a first cut at developing a collection of knowledge, a chart might include a set of points representing each successful rocket design that has reached orbit.

The point might be located on the chart based upon mass at liftoff vs mass in orbit.

Color of each point might be determined by the number of stages. None of the points would show SSTO from Earth, but SSTO from the Moon has been demonstrated, and SSTO from Mars has been described by GW Johnson in multiple topics and in YouTube videos.

I am hoping to enlist the talent assembled in this forum to create a work product that will be useful to a wider audience.

(th)

tahanson43206 · 2024-05-15 06:47:10

For kbd512 re analysis of SSTO based upon Shuttle external tank as a starting point...

I've added that post to the index for the topic in #2

If you have time, I'm wondering if you might be able to provide a summary of all that work at the bottom...

1) Would the design work?
2) How many passengers can be transported to LEO?
3) The goal is a reusable aircraft-like vehicle... can the vehicle you've described return from LEO?

I still think RGClark is on a wild goose chase, but he's stimulated thinking by members of the forum, and your support in particular seems encouraging.

Does your design have enough fuel left over for descent and landing?

A lifting body design might help with the return problem, but a burn is still needed to drop the vehicle out of LEO after the passengers exit.

Return of passengers to Earth may remain the domain of the TSTO designs. The risks are simply too great with that huge SSTO.

However, success with the SSTO for lifting passengers might provide the financial incentive to pursue it.

The huge vehicle you've described would seem to call for a large number of passengers to justify the investment.

Return to Earth in smaller TSTO vehicles would spread the risk, so that market seems assured.

(th)

SpaceNut · 2024-05-15 17:43:46

Shuttle tank was a throw away tank that did not stay with the shuttle as part of its dry mass.

kbd512 · 2024-05-16 09:26:04

tahanson43206,

1. Engineering determines what does or does not fly, not opinions about what "looks reasonable". What is "reasonable" for metal aircraft with significnat secondary structures, especially heavy ones subjected to thousands vs hundreds of takeoffs and landings, higher limit g-loads, using higher safety factors than reusable orbital launch vehicles, is not the same as for composites.

A chapter from a book entitled "Solidification", by Hongfei Zheng, Xuesen Zeng, Jianbao Zhang and Hongjie Sun, primarily about the fabrication of cryo tanks by NASA, and covers many of the important aspects of fabrication:
The Application of Carbon Fiber Composites in Cryotank

This NTRS document is from 2013:
STRUCTURES AND DESIGN PHASE I SUMMARY FOR THE NASA COMPOSITE CRYOTANK TECHNOLOGY DEMONSTRATION PROJECT

Another NTRS document:
Design, Manufacture and Test of Cryotank Components

Note how thick plies were used to make the fabrication process faster. We're not worried about manufacturing speed. We want quality and low weight, which means thin plies and autoclaving, but less weight and very low porosity if you look at the pictures. Using composites to save money is one application of these materials, but this vehicle requires higher strength-to-weight performance. If it takes 2 weeks or even 3 weeks to lay the plies vs 1 week, who cares? We're not making expendable cryo tanks for SLS upper stages, and there's one or at most two operators babysitting the machine. NASA used T700 and T800 fibers. We're using T1100 fibers. There's a healthy increase in the tensile strength of the fibers and therefore the composite- 400ksi (T700 and T800) to 500ksi (T1100) is pretty significant. When NASA performed their testing, they achieved a 42.9% mass reduction over Al-2195 using weaker TorayCA T700 and T800 fibers. We're using significantly stronger T1100 fibers. We also have CNT and BNNT fibers that make T1100 look rather weak by way of comparison. All composite primary structure for rockets has been a series of baby steps. This is not a "giant leap", it's a comprehensive application of all the best technologies and practices into a single vehicle.

Speaking of composites, NASA is actively working on non-regeneratively cooled Reinforced Carbon-Carbon rocket engine nozzles with UHTC coatings that prevent very high temperature oxidation / erosion from the hot exhaust gases, and progress has been superb, meaning multiple successive firings with minimal erosion of the RCC's protective coatings with little to no cracking. The reason for this is simple- RCC nozzles are half to a third of the weight of Copper and Nickel or steel alloy regeneratively cooled metal nozzles, plus a significant decrease in engine complexity related to active nozzle cooling. If the only component regeneratively cooled is the throat, then you can save quite a bit of weight.

The military is starting to replace Titanium and high strength steel alloys with composite landing gear structural components, namely all the heavy steel drag braces, oleo strut fixtures, etc. For example, these components are incorporated into our F-16 fighter jets and various military helicopters, some of which have all CFRP-composite gear except for steel axle pins and bolts. We're going a step beyond, by implementing rubberized Aramid (Kevlar) fabric reinforced tracked gear with composites road wheels to save weight and greatly reduce ground pressure over heavier yet much lower contact surface area Nitrogen-filled rubber tires which are subject to bursting from over-speed landings or overpressure from heating. Using a little extra power to tow a tracked gear aircraft back to the hangar is not a big deal. Reducing ground pressure to a 1/3rd of what it would be with rubber tires, is a very big deal. In an emergency, this thing could land on a dry lake bed or a flat field, unlike virtually any airliner, because ground pressure is too high with rubber tires, so the wheels sink into the ground, and shear off, frequently flipping the vehicle. This is not something we want to make a habit of doing, but landing options are good to have when piloting a glider.

People keep pointing back at the X-33 as some sort of "proof" that composite propellant tanks or SSTOs are impossible. That was 30 years ago. Both engine and composites technology has moved far beyond what was achievable in the 1990s. It's time for people stuck in the past to move on as well. The composite propellant tank problems of the X-33 / VentureStar program have since been resolved in multiple different ways. If they were not, then there would not be expendable vehicles, and now partially reusable man-rated vehicles as well, routinely going into orbit with composite propellant tanks and other flight-critical structures such as landing gear on Falcon 9 boosters.

2. I want to seat, or more like "strap-in", 500 passengers.

I can only provide mass estimates for physically fit young adults. Most fit young women will weigh 50kg or less. Most fit young men will weigh 82kg or less. There are always outliers, but we're shipping pairs of fit young men and women. That means the nude weight of the pair of passengers is 132kg, and there will be 250 pairs, so 33,000kg in total. If I had 6 foot tall women, at 59kg, and 6 foot tall men, at 83kg, then 35,500kg. We're not taking obese people to Mars. For starters, they may not survive the ride to orbit. Secondly, someone who does not have the personal discipline to control the one thing the overwhelming majority of young adults have complete control over- how much food they eat and how much exercise they partake in, is not someone you want to spend the rest of your adult life inside a tin can with.

The Final Frontier Design pressure suit weighs 4.5kg, which equates to about 2,250kg for all 500 passengers.
A lightweight sealed O2 line equipped helmet (polycarbonate visor, BNNT composite shell, aerogel foam impact protection) will weigh about 0.5kg, so 250kg.
Soft booties (thick synthetic cushioning sock-like material with ankle protection and traction) will weigh about 0.5kg per pair, so another 250kg.
2L of water per passenger weighs 1,000kg. You'll be provided with 3 meals, at 1kg per person, another 500kg.

pax = passenger

35,500kg max pax + 2,250kg pax suits + 250kg pax helmets + 250kg pax boots + 1,000kg pax H2O + 500kg pax food. That means my payload, less seating, is 39,750kg. The "seating arrangements" are more like "strapping arrangements". Everyone is strapped in, on a floor / bulkhead, lying on their back on a pad, for both high g-tolerance and weight. They aren't taking anything else with them, because there's no room or weight to spare. Personal belongings will be delivered directly to their awaiting colonization ship using Starship cargo carriers.

3. Yes, the craft can return from orbit. It has a thermal protection system included in the mass estimate, but again, one made from modern lighter / stiffer / stronger / higher heat tolerance materials.

There's a lot of use of aerogel foams and woven BNNT fabrics on top, which is the material NASA is testing for heat shielding applications for reentry. The tiled bottom is TUFI, which protects from temperatures of up to 2,482°C and weighs 4.4lbs/ft^3, and of course, more aerogel foam, or felt actually, for bonding the tiles to the vehicle. Space Shuttle tiles were 12lbs/ft^3. Modern TUFI tiles, an improvement on Space Shuttle tiles, is what makes this possible, not belief. These tiles have already been flown aboard the X-37- a reusable military space plane. Similarly, the BNNT fabrics and aerogels have been tested in NASA's "blow-torch" tunnel, as I call it. These materials work, they can be used, and they have been extensively tested, as well as being the subject of active ongoing testing and refinement efforts.

We developed all these technologies, specifically for the applications we intend to use them for, so let's use everything we've fully developed.

tahanson43206 · 2024-05-16 10:32:46

For kbd512 re SSTO 500 passenger transport...

That vision is a good companion/complement to Large Ship.

Could you use an entire forum to provide a framework?

SpaceNut is thinking about creating a new category for Projects.

He has experimented with the idea in the clone, where changes can be made without risk.

I understand you don't have time to read Housekeeping, so I'll just invite you to assist SpaceNut in thinking through what the new structure might look like.

I'm interested in seeing a gradual introduction of achievement into the NewMars history. We have GW Johnson's course material to count as a win, and we have Large Ship as a well established root, from which an entire forum could develop.

As a reminder, (mostly for NewMars members) the structure here is:

Category (like Meta New Mars)...

Forum (like Mars Society)

Topics without limit

Posts within topics again without limit

My proposal is:

Category: Projects

Forum: Large Ship

Topics: As many as are needed

Posts: As many as are needed

***
In your case (if you are interested)...

Project Category

Forum: SSTO 500 Passenger Transport

Topics: As many as are needed

Post within topics: As many as are need.

The structure ** should ** provide the framework needed to move from vision to fact in a series of steps

A 500 passenger transport would be a goal to be achieved.

A single passenger SSTO would be a step along the way.

To my knowledge (admittedly limited) there exists on Earth today NO such vehicle.

An organization intending to build one will necessarily be at the bleeding edge of human capability.

That means failure will occur, and it will take persistence and stamina to overcome failure.

A first step in the long sequence that would lead to a successful flight starts with the simple decision on how to structure the environment.

SpaceNut is thinking about the idea of creating a new Category for Projects.

What would it take to help SpaceNut to move from contemplation to action?

(th)

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