GW Johnson Postings and @Exrocketman1 YouTube videos

tahanson43206 · 2024-08-15 18:31:00

This post is intended to hold links to two possible book covers:

Version 1 of 2

and.... Version 2 of 2

(th)

tahanson43206 · 2024-08-16 06:31:24

For GW Johnson about possible book project...

Overnight, it came to me that we might begin the book where you begin your course, with the ellipse...

Johannes Kepler discovered that planets travel in ellipses.

Kepler achieved success in part by securing the data collected by Tycho Brahe.

It seems to me that the book might open with a page asserting that all objects moving in the Solar System travel on ellipses.

The back of that page would have PhD level math associated with ellipses.

The next page would introduce Kepler as the discoverer of the elliptical path for planets.

The back of that page would contain links to as many references to Kepler's life and discoveries as can be packed into the space.

The next page would introduce Tycho Brahe and the back of ** that ** page would contain links to his life and discoveries.

As I am thinking about this, references to the telescopes named after these gents would be worth adding to the collection if there is room.

Perhaps the back pages could include a pointer (link) to a comprehensive index of references, instead of trying to pack everything into the limited space.

I haven't thought beyond Brahe, but at some point it would be appropriate to introduce Copernicus. His insight was significant in evolution of human understanding of how the Universe actually works.

Galileo needs to be brought in somewhere in the early pages.

www.skyatnightmagazine.com has a list of 50 famous astronomers.

The list starts with Hipparchus (circa 190-120 BC) ... I associate Hipparchus with the framework we still use today.

Wikipedia reminded me that Hipparchus is associated with the invention of trigonometry.

The mission of the book needs to be restated on every page.... The student is to be able to select a star for a burn, and to specify both the amount of thrust and the duration of the burn, to reach the goal.

It might be possible to use the well known fabric-of-space model to show (with animation) the behavior of objects in a mix of gravitational fields. In particular, the flight from Earth to Mars would be shown as from one depression around Earth to another around Mars, while all the while moving in the Sun's massive slope.

(th)

SpaceNut · 2024-08-16 16:26:08

I just love the cover art its perfect....

tahanson43206 · 2024-08-16 18:03:47

For SpaceNut re #378

Your appreciation goes a ** long ** way!

Thanks!

(th)

tahanson43206 · 2024-08-19 12:50:45

searchterm:ramjet

GW Johnson published a book on ramjets...

Here is a link to the table of contents:

https://www.dropbox.com/scl/fi/un4aj76t … d06sc&dl=0

The is a summary of the contents of the chapters.

This space is reserved for order information.

GW does not yet have a site that automates payment and download of the ramjet book as a single
item. Watch for when that situation changes.
The base price for the 561-page book is $100 US, plus $6.25 rural Texas sales tax, for an invoice
total of $106.25 US.
Currently, he accepts payments in the form of mailed checks or Western Union money transfers.
Overseas customers in particular like to use Western Union, and don’t seem to even use paper
checks at all anymore.
Once paid, GW then manually sends the book as multiple pdf files sent in multiple emails, at 3
files to the email to stay well within the various email system attachment size limitations. There are
27 such files, sent in a series of 9 emails: 22 files at 1 chapter per file, plus 4 files at 1 appendix per
file, plus 1 file for the “up-front” stuff (foreword, table of contents, etc).
If you choose to use Western Union, you will need GW’s full name and address as it appears on his
driver’s license ID. That is given just below. He will need the tracking number Western Union gives
you, in order to retrieve the money.
Gary Wayne Johnson
5886 New Windsor Parkway
McGregor, TX 76657

(th)

GW Johnson · 2024-08-22 08:46:05

I could not quickly find the right thread for this, so I put it here. This is from today's AIAA "Daily Launch", referring to a longer article in something called Ars Technica.

Ars Technica

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

NASA would like to start stacking the Space Launch System rocket for the Artemis II mission—the first human flight around the Moon since 1972—sometime next month, but the agency's exploration chief says the milestone could be delayed as engineers continue studying the readiness of the Orion spacecraft's heat shield.

My take on it:

NASA still clearly does NOT (officially) understand why the Artemis I unmanned flight test heat shield experienced irregular spalling and material loss when the first (before Artemis) Orion flight test heat shield did not! You can bet the actual engineers understand, but that answer was (and still is) not what upper NASA management wanted to hear!

The difference between the two unmanned test flight heat shields is as plain as he nose on my face: the first heat shield ablative was reinforced by the hex cell structure into which it was gunned, cell-by-cell, which is effectively a fiber-reinforced composite as it ablates. There was no hex cell structure in the Artemis I heat shield, and it experienced excessive and erratically distributed material loss.

No fiber-reinforced composite effect in the second test, and it performed badly. Surprise, surprise! Experiment trumps computer modeling results, EVERY SINGLE TIME!

The trouble is, as managed, the project built and installed the heat shield on the Artemis II Orion before they understood what happened to Artemis I during that test, and they built it the same way they built Artemis I. Problem: the Artemis I result so very clearly said "go back to the Apollo-style gunned-in-hex-cell construction technique".

That would mean removing the already-installed heat shield from the Artemis II capsule (or just replacing the entire capsule), and replacing that heat shield with a new one made with the old Apollo technique. They did NOT want to spend the $ to do that! Nor did they want to admit a program management error, and a rather egregious one, at that!

They've had the time to replace the heat shield with one that would perform properly, but they didn't do that work, instead hoping the engineers could find some excuse to fly anyway. And now, FINALLY, somebody in a responsible position somewhere is starting to worry about killing the Artemis II crew with a faulty heat shield design, just as they are ready to stack the SLS rocket and go fly!

$ vs lives! $ vs management reputations! Where have we seen this movie before?

GW

Last edited by GW Johnson (2024-08-22 08:57:07)

tahanson43206 · 2024-08-22 19:11:37

For GW Johnson re heat shields....

In a very recent post in another topic, Calligan reported this:

Regarding the titanium dioxide waste produced from ilmenite production. I remember reading a proposal to make reentry heat shields out of it. It is a high melting refractory. If we can make heat shields in space, it frees up a lot of Earth lift off mass for payload.

Are you familiar with this idea?

(th)

GW Johnson · 2024-08-22 21:56:35

Titanium dioxide is THE most common white pigment used in every sort of paint made anywhere on the planet! It's a fine white powder. Yes, the meltpoint is high, but how does one go about turning a white dust into a real structural material? A heat shield must withstand high temperatures, but also must stay intact and in place in the face of high fluid pressures and shearing forces.

GW

PS: the movie reruns not only include the fatal shuttle Challenger and Columbia disasters (two dead crews of 7, twice), but now two stranded Starliner astronauts.

tahanson43206 · Yesterday 08:06:39

For GW Johnson...

At the post below, I have reported a conversation with Gemini (Google's AI search engine) that indicates Gemini found records indicating that the Apollo heat shield design may have been classified during the Cold War.

https://newmars.com/forums/viewtopic.ph … 85#p225985

A Freedom of Information Act request might be able to release that information, if it is indeed still classified.

(th)

GW Johnson · Yesterday 09:08:51

The Apollo heat shield was "hex-gunned Avcoat", and that's no secret, not today. It exists in multiple variations. This Apollo hex-gunned Avcoat was also what flew on the Orion in its very first unmanned flight test, before the unmanned Artemis-I flight test.

The phenolic-impregnated fiberglass honeycomb is attached to the capsule base with the hex cells facing into the wind blast direction during entry. Humans wielding powered "caulking guns" inject the ablative manually into those hex cells. There were almost 300,000 of them on Apollo, almost 400,000 of the larger Orion. The ablative is cured in place, and resurfaced by the equivalent to coarse sanding to smoothe the shape.

The ablative was a silicone polymer (not sure which one right off the top of my head, but I think that it is listed in the Wikipedia article on Avcoat), loaded with small micro-balloons to reduce its density. Lower density is lower heat shield mass, but also a faster ablation rate. The density you want to use is a trade-off, set by the mission to be accomplished. That heat shield material and construction information might once have been militarily classified long ago, although I don't really think so. More likely it was a company trade secret that NASA tried to protect for a while.

This technology grew from very similar materials tried experimentally on Mercury and Gemini, both built by McDonnell (before it merged with Douglas). Some of the early Mercury suborbital tests were made with a metal beryllium heat shield, but they quickly went to ablatives as the better-performing and lighter-weight deal. What flew on Gemini was a very close precursor to what flew on Apollo. Apollo was built by North American Rockwell. NASA had to be the technology source and guardian for this heat shield information, since this was used by two different competing companies for NASA. A lot of the development tests in arc jet facilities were done by NASA.

NASA management did not like two things about the Apollo-style hex-gunned Avcoat: (1) the enormous manual labor cost, and (2) the inherent variability in manually-loading hex cells. It takes a skilled and well-practiced operator to get consistent results, and you have to pay those skilled operators more.

So what they did for the Orion that flew in Artemis-I was delete the hex attached to the capsule base, and instead just bond down cast tiles made of the Avcoat balloon-loaded polymer, but without any hex cell reinforcing material embedded in it. And they built the Orion for the manned Artemis-II test flight the same way as they built the one for Artemis-I, BEFORE Artemis-I actually flew! They really thought it was going to work based on computer simulations and some arc jet data to set the density.

But it did not work right on the Artemis-I test! Unreinforced char is a lot easier to strip away with fluid surface shear forces. You don't get a lot laterally-directed surface shear in a straight-on arc jet test, which is the way those are usually done. And you only can get what you know to program-in, in computer simulations! GIGO! I am guessing they never ran any angled arc jet tests, because they never did before, with the hex-reinforced Avcoat samples.

The original real management mistake was building the Artemis-II heat shield before getting the flight test results from the Artemis-I flight test. They did that to save schedule time, betting that it would work fine. But it didn't.

The follow-up mistake was not switching heat shields back to the hex-gunned method on that Artemis-II Orion, when Artemis-I showed bad results. There's been enough other delays to completely cover the time needed to do that, but they did not, because that would require publicly admitting a top management mistake!

And as we have already seen since Challenger, they NEVER want to admit top management mistakes! That culture never changed, or there would not have been a Columbia disaster. Or two stranded Starliner astronauts aboard ISS.

The track record indeed shows that money, schedule, and management reputation are all valued more than human lives. At NASA, and even at the "old space" big corporate contractors.

As far as NASA goes, that bad, still-unfixed, management culture is a separate problem from the Congressional (incompetent) micromanagement of NASA projects, just to support high-$ Congressional pork-barrel politics.

However, be that as it may, until BOTH those fatal problems are fixed, NASA will not successfully send anybody back to the lunar surface, much less to Mars!

GW

tahanson43206 · Yesterday 09:26:22

For GW Johnson re Apollo design for heat shields (Post #385)

Thank you for reminding us of the manual labor required to create the Apollo heat shields, and the one Aremis shield that (I gather) was successful.

The problem of manual labor has been solved for years by automobile manufactures in the US and around the world.

A robot arm can place exactly the right amount of material in as many locations as your project requires.

The fact that no one has adopted what is standard practice in industry tells me that there is a problem with acceptance of technology from outside NASA.

There are some who advocate for keeping older employees because of their body of experience. But the risk is that older employees cannot allow themselves to take the risk of trying new ways of doing things.

In this case, it appears (as I understand the situation) that while it was clear that using manual labor to fill hex cells was a proven successful technique, no one was able to make the mental leap to think of using a modern robot to do the work. In fact, multiple smaller robots could be choreographed to fill hex cells at a pace competitive with the best human workers.

This means there is a business opportunity for an entrepreneur who can develop a plan to make heat shields for Lunar and Mars return flights., using the tried and true Apollo hex cell technique.

(th)

GW Johnson · Yesterday 14:49:50

What would be wrong with using a simple press and a single press operator, instead of some expensive high-tech robots, to squish the polymer down into the cells of a block of the phenolic-impregnated fiberglass hex, inside some suitable mold tooling? Then force that uncured item down into the mold of a heat shield tile, and then butter it over with the polymer, and smooth its surface with a trowel? Then cure the whole thing at once?

Anybody who has ever actually built stuff putting goo into structures with his own hands could have thought of that!

GW

tahanson43206 · Yesterday 15:09:01

For GW Johnson re #387

A related question is why the original Apollo mission planners decided to go with the design they did?

Information about the original heat shields seems to be available in various locations. In a quick scan I found hints that the base of the shield was a single piece of metal over which the fiberglas honeycomb appears to have been laid. I get the impression the material to fill the hex cells was manually delivered with painstaking attention to detail.

It seems to me your question deserves an answer but it may be a challenge for members of this group to discover why such a simple sounding procedure was not followed.

I think it likely that the fate of the crew and the reputation of the Nation depended upon doing the shield correctly the first time, so it's possible the engineers who planned and carried out that work were in no mood to take chances or cut corners.

Now, 50 years on, perhaps the fabrication method you've proposed would make sense, and if that is the case, I see a business opportunity for a company that specializes in heat shields for the return from deep space. Heat shields for return from Earth orbit appear to be well understood at this point.

(th)

tahanson43206 · Today 09:11:15

Here are two more possible book covers for "So! You want to be a Space Pilot"

The age group of interest for this project is 9-12

(th)

SpaceNut · Today 12:05:57

The images might also be a flip book due the illustrations for a much younger audience.
Add in the colorful star charts and nebula's and we have sparked interest for a lifetime.

tahanson43206 · Today 12:39:20

For SpaceNut re #390

Thanks for your interest in and support of the proposed book project.... Your suggestion is definitely interesting and one i'll be considering...

It is possible you might have missed a detail or two of how the book is evolving, and much is going on via email. The working concept is to have the odd numbered facing pages designed for the 9-12 age group, with mostly artwork and just a few words.

The back of each such page is to contain the PhD level mathematics and text, along with diagrams and figures, to back up the front page.

For example, if the first page highlights the ellipse as the most important orbital trajectory for a Space Pilot to understand, the back will show the equations that define the ellipse, along with links to resources that explain the math at an adult level. The idea is to place the adult symbols and language in front of the student so they become familiar while they remain totally mysterious. As the student progresses, more and more of the math will come into play.

I'm also hoping to be able to provide online resources to animate the front page, and perhaps some of the back page.

(th)

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#376 2024-08-15 18:31:00

Re: GW Johnson Postings and @Exrocketman1 YouTube videos

#377 2024-08-16 06:31:24

Re: GW Johnson Postings and @Exrocketman1 YouTube videos

#378 2024-08-16 16:26:08

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#379 2024-08-16 18:03:47

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#380 2024-08-19 12:50:45

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#381 2024-08-22 08:46:05

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#382 2024-08-22 19:11:37

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#383 2024-08-22 21:56:35

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#384 Yesterday 08:06:39

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#385 Yesterday 09:08:51

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#386 Yesterday 09:26:22

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#387 Yesterday 14:49:50

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#388 Yesterday 15:09:01

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#389 Today 09:11:15

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#390 Today 12:05:57

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#391 Today 12:39:20

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