GW Johnson Postings and @Exrocketman1 YouTube videos

tahanson43206 · 2025-01-20 14:16:58

Preview of Coming Updates....

GW Johnson has updated the spreadsheet and user documentation.

The original version(s) will remain in place for comparison if anyone is interested.

The new version replaces one of the sheets with a new one designed to concentrate on the g force and to provide heat/toe gradient.

The question is to what extend a difference of G force at the head vs feet will result in mental issues for crew and passengers.

The Baton style ship design is looking ** really ** good as each day passes, and the advantages of the design become more clear.

Here is the updated spreadsheet:
https://www.dropbox.com/scl/fi/q6itfabc … rbppk&dl=0

And here is the updated User Manual:
https://www.dropbox.com/scl/fi/pk2px3z4 … z76y3&dl=0

(th)

tahanson43206 · 2025-01-22 12:18:29

This post offers Version 3 of the Spin spreadsheet and User Manual.

This one has an improved general solution sheet.

Spreadsheet:
https://www.dropbox.com/scl/fi/03vk5b97 … 34szm&dl=0

User Manual:
https://www.dropbox.com/scl/fi/5zyueuhi … 112kv&dl=0

GW Johnson · 2025-02-10 13:31:17

Major news from AIAA’s “Daily Launch” email newsletter for Monday 2-10-2025, with link to a longer Ars Technica article that reproduced here. The 1st 3 paragraphs were in the “Daily Launch”.
---
Boeing has informed its employees of uncertainty in future SLS contracts

The White House has not made a final decision yet on the large rocket

By Eric Berger, senior space editor at Ars Technica, 7 Feb 2025

The primary contractor for the Space Launch System rocket, Boeing, is preparing for the possibility that NASA cancels the long-running program.

On Friday, with less than an hour's notice, David Dutcher, Boeing's vice president and program manager for the SLS rocket, scheduled an all-hands meeting for the approximately 800 employees working on the program. The apparently scripted meeting lasted just six minutes, and Dutcher didn't take questions.

During his remarks, Dutcher said Boeing's contracts for the rocket could end in March and that the company was preparing for layoffs in case the contracts with the space agency were not renewed. "Cold and scripted" is how one person described Dutcher's demeanor.

Giving a 60-day notice

The aerospace company, which is the primary contractor for the rocket's large core stage, issued the notifications as part of the Worker Adjustment and Retraining Notification (or WARN) Act, which requires US employers with 100 or more full-time employees to provide a 60-day notice in advance of mass layoffs or plant closings.

"To align with revisions to the Artemis program and cost expectations, today we informed our Space Launch Systems team of the potential for approximately 400 fewer positions by April 2025," a Boeing spokesperson told Ars. "This will require 60-day notices of involuntary layoff be issued to impacted employees in coming weeks, in accordance with the Worker Adjustment and Retraining Notification Act. We are working with our customer and seeking opportunities to redeploy employees across our company to minimize job losses and retain our talented teammates."

The timing of Friday's hastily called meeting aligns with the anticipated release of President Trump's budget proposal for fiscal-year 2026. This may not be an entire plan but rather a "skinny" budget that lays out a wish list of spending requests for Congress and some basic economic projections. Congress does not have to act on Trump's budget priorities.

Multiple sources said there has been a healthy debate within the White House and senior leadership at NASA, including acting administrator Janet Petro, about the future of the SLS rocket and the Artemis Moon program. Some commercial space advocates have been pressing hard to cancel the rocket outright. Petro has been urging the White House to allow NASA to fly the Artemis II and Artemis III missions using the initial version of the SLS rocket before the program is canceled.

Critics of the large and expensive rocket—a single launch costs in excess of $2 billion, exclusive of any payloads or the cost of ground systems—say NASA should cut its losses. Keeping the SLS rocket program around for the first lunar landing would actually bog down progress, these critics say, because large contractors such as Boeing would be incentivized to slow down work and drag out funding with their cost-plus contracts for as long as possible.

On Saturday, a day after this story was published, NASA released a statement saying the SLS rocket remains an "essential component" of the Artemis campaign. "NASA and its industry partners continuously work together to evaluate and align budget, resources, contractor performance, and schedules to execute mission requirements efficiently, safely, and successfully in support of NASA’s Moon to Mars goals and objectives," a spokesperson said. "NASA defers to its industry contractors for more information regarding their workforces."

Long-delayed and expensive

Friday's all-hands meeting indicates that Boeing executives believe there is at least the possibility that the Trump White House will propose ending the SLS rocket as part of its budget proposal in March.

The US Congress, in concert with senior leaders at NASA, directed the space agency to develop the SLS rocket in 2011. Built to a significant degree from components of the space shuttle, including its main engines and side-mounted boosters, the SLS rocket was initially supposed to launch by the end of 2016. It did not make its debut flight until the end of 2022.

NASA has spent approximately $3 billion a year developing the rocket and its ground systems over the program's lifetime. While handing out guaranteed contracts to Boeing, Northrop Grumman, Aerojet, and other contractors, the government's rocket-building enterprise has been superseded by the private industry. SpaceX has developed two heavy-lift rockets in the last decade, and Blue Origin just launched its own, with the New Glenn booster. Each of these rockets is at least partially reusable and flies at less than one-tenth the cost of the SLS rocket.

---

My take:

I was expecting to see Starliner cancelled before SLS, but it may work out to be SLS first. We will see if Trump’s sowing chaos can overcome the entrenched pork-barrel politics of powerful Senators. Meanwhile, even the Artemis moon program itself could possibly be on the chopping block. That was definitely hinted in the Ars Technica article, in the 7th of 12 paragraphs.

GW

Last edited by GW Johnson (2025-02-10 13:33:15)

tahanson43206 · 2025-02-16 18:53:36

This post is intended to hold a link to an image that GW created to try to help NewMars readers to understand the production of steam.

The question came up in the context of the lighter than air topic.

(th)

tahanson43206 · 2025-02-25 11:35:30

This post is to collect the four images that GW Johnson created recently, in response to the 15 Days to Mars scenario of PhotonBytes, and the 2024 YR4 asteroid discussion that is current:

2024 YR4

15 Day Trip Scenario

Fast Trip propulsion:

USAF "Orion" concept

(th)

GW Johnson · 2025-02-27 12:17:21

Wasn't sure where to put the various pieces of this, so I put the whole thing here. There are several items of interest to correspondents on these forums.

From AIAA’s “Daily Launch” for Thurs 2-27-2025. The longer form of the article is on the Ars Technica site, but this short blurb tells the tale.

ARS TECHNICA

Long-time advocate of SLS rocket says it’s time to find an “off-ramp”

One of the Republican space policy leaders most consistently opposed to commercial heavy lift rockets over the last decade—as an alternative to NASA's large SLS rocket—has changed his mind. "We need an off-ramp for reliance on the SLS," said Scott Pace, director of the Space Policy Institute at George Washington University, in written testimony. He issued the statement in advance of a hearing about US space policy, and the future of NASA's Artemis Moon program, before a subcommittee of the House Committee on Science, Space, and Technology.

NEW YORK TIMES
Intuitive Machines’ Athena Lander Launches on Journey to the Moon

Intuitive Machines landed a robot on the moon last year. Can the Houston company do it again, but keep the spacecraft upright this time? The company’s second lander, named Athena, launched on Wednesday evening on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida. It is now on an arcing path to the moon.

FLYING MAGAZINE
FAA Advises Boeing 757 Freighter Operators to Evaluate Cargo Doors

The FAA has issued a Special Airworthiness Information Bulletin (SAIB) advising operators of Boeing 757-200 freighter planes to be aware of an “airworthiness concern” regarding the main deck cargo door opening while in flight. The bulletin, issued Friday, stated that this concern is not an unsafe condition that would warrant airworthiness directive (AD) action, though FAA investigations into the matter are still ongoing.

My take on the B-757: this one has been out there for decades. It is far more likely this is a wear-out issue than it is some sort of design flaw.

AVIATION WEEK NETWORK
SpaceX Details Starship Mishap Findings, Changes For Next Test

SpaceX has made design changes to the Starship launch system for its eighth flight test in response to the spectacular breakup of the upper stage during its most recent test, which it believes was caused by a harmonic response that stressed the onboard hardware, leading to a fire and loss of the vehicle.

This paragraph was the first paragraph of the longer article on Aviation Week’s site, with the rest of it copied and reproduced here. My take is that there has been some sort of flying airframe-related problem that does not show up in the ground tests, at McGregor, or static fires at Boca Chica. This is the sort of surprise that often happens once you get to flight test. Here is the rest of the article:

The next flight could happen on Feb. 28, pending regulatory approval, SpaceX said on its website. The objectives set for the test include Starship’s first payload deployment, which it failed to achieve last time, and reentry experiments geared toward returning the upper stage to the launch site. SpaceX will again aim to replicate the success it has had twice in catching the Super Heavy booster first stage.

“Several hardware and operational changes have been made to increase reliability of the upper stage,” the company said. Those include changes to fuel feedlines connecting the vacuum engines, propellant temperature changes and a new operating thrust target.

In its Feb. 24 mishap report, SpaceX said: “The most probable root cause for the loss of ship was identified as a harmonic response several times stronger in flight than had been seen during testing, which led to increased stress on hardware in the propulsion system. The subsequent propellant leaks exceeded the venting capability of the ship’s attic area and resulted in sustained fires.” The unpressurized attic is the section between the bottom of the liquid oxygen tank and aft heat shield.

SpaceX said the first indication that something was going wrong came about two minutes into the burn of the second stage when a flash was detected near one of the six Raptor engines. Sensors then detected a rise in pressure, suggesting a leak. Two minutes later another flash occurred, sparking sustained fires in the attic. Five of six Raptor engines then shut down and communications with the vehicle was lost 8 min. 20 sec. into flight, SpaceX said.

Three minutes after contact was lost the vehicle broke apart. “Post-flight analysis indicates that the safety system did trigger autonomously, and breakup occurred within Flight Termination System expectations,” SpaceX said.

The company said it subsequently performed a 60-sec. static fire with the Starship due to fly in the upcoming test. It involved different thrust levels and Raptor configurations to try and replicate and address the issues that led to the mishap.

SpaceX said additional changes being made to reduce flammability include adding more vents and introducing a new purge system utilizing gaseous nitrogen to reduce propellant leak risk. “Future upgrades to Starship will introduce the Raptor 3 engine, reducing the attic volume and eliminating the majority of joints that can leak into this volume,” it said.

In the next flight, SpaceX plans to deploy four Starlink simulators sized to replicate the next-generation of its low-Earth-orbit communications satellite system. The upper stage will also aim to relight a Raptor engine while in space. The company also aims to collect data on the upper stage’s heat shield. “Starship’s reentry profile is designed to intentionally stress the structural limits of the upper stage’s rear flaps while at the point of maximum entry dynamic pressure,” SpaceX added.

The Super Heavy booster also sports new features, including a more powerful flight computer, upgraded power and upgraded power and network distribution.

Robert Wall

Robert Wall is Executive Editor for Defense and Space. Based in London, he directs a team of military and space journalists across the U.S., Europe and Asia-Pacific.

GW

Last edited by GW Johnson (2025-02-27 12:18:25)

tahanson43206 · 2025-03-01 14:53:27

For all ...

GW Johnson created an "Elevator Pitch" for his course on Basic Ellipses ...

https://www.youtube.com/watch?v=i_K7ElRs1yk

Please pass this link along to anyone you might know who is a teacher or in position to pass it along to prospective students.

If you have a local newspaper and they have an input service (such as letters to the editor) please consider sending the link so they might publish it as a public service.

Thanks to everyone for helping. GW's been working on this for several years, and NewMars is lucky enough to be able to serve as a platform for delivery.

Potentially, if we are ** really ** lucky, we might eventually come to the attention of students for possible membership in the forum itself.

(th)

tahanson43206 · 2025-03-02 07:57:51

For GW Johnson!

It looks to me as though Firefly created a "real" drill for their Moon expedition:

They might be interested in your Mars drill concept.

CAPE CANAVERAL, Fla. (AP) — A private lunar lander carrying a drill, vacuum and other experiments for NASA touched down on the moon Sunday, the latest in a string of companies looking to kickstart business on Earth's celestial neighbor ahead of astronaut missions.
Firefly Aerospace’s Blue Ghost lander descended from lunar orbit on autopilot, aiming for the slopes of an ancient volcanic dome in an impact basin on the moon’s northeastern edge of the near side.
Confirmation of successful touchdown came from the company's Mission Control outside Austin, Texas, following the action some 225,000 miles (360,000 kilometers) away.

(th)

tahanson43206 · 2025-03-05 10:31:54

For all!

North Houston chapter of National Space Society has kindly agreed to publicize Dr. Johnson's course on ellipses >> orbital ellipses

The course is hosted here on the NewMars forum! This is an opportunity for the NewMars forum to come to the attention of young people and their parents.

The next meeting of the North Houston chapter of National Space Society is this coming Saturday March 8, 2025

The hour should be convenient for our European members. It is 14:00 Houston time, 15:00 New Hampshire time and 20:00 London time.

Attendance via Zoom provides audio and video of the event. Attendees do not need camera or microphone.

Monthly Meeting – March 8, 2025 – SEFH Winners
This will be a hybrid meeting. Come in person at Barbara Bush Library (6817 Cypresswood Drive, Spring, TX 77379) or join us online using Zoom: https://us02web.zoom.us/j/85216600533.
The meeting will be on Saturday, March 8, 2025 at 2PM (US Central Time).
(Still working on the details of the agenda. Latest is on the website: https://www.northhoustonspace.org/ )
2:00 PM – Opening Remarks
2:10 PM – Latest in Space Weather – Patricia Vlach
2:30 PM – Space News – Greg Stanley
3:00 PM – Science and Engineering Fair of Houston (SEFH)
Booth and Fair – Robert Hall
Judging – Christean Kapp
Presentations by each of the winners of the North Houston Space Society Awards
4:00 PM – End of Meeting at the Library
(as soon as we can get there)
5:00 PM – Informal get together at PJ’s Coffee near the library
Logo
Copyright (C) 2025 NSS North Houston Space Society. All rights reserved.
Our mailing address is:
NSS North Houston Space Society 9327 Swansea Bay Dr Spring, TX 77379-3638 USA

An announcement about Dr. Johnson's course was moved from March to April.

However, NewMars readers can view the video now: https://www.youtube.com/watch?v=i_K7ElRs1yk

(th)

tahanson43206 · 2025-03-06 15:42:01

GW Johnson put together a flyer for the Orbits class...

https://www.dropbox.com/s/cja3bo5ju1bbz … 4vg7y&dl=0

If any of our NewMars members have friends with kids of the right age, please print a copy and hand it out.

The flyer will be distributed at the March meeting of the North Houston chapter of NSS this coming Saturday, at 14:00 Houston time, 15:00 New Hampshire time, and 20:00 London time.

Feedback is welcome.

Our goal is to improve the course so it is as easy to use as possible.

We are making the claim that a student who completes the course will be able to create documents similar to the one in the image below.

Image here as soon as I find the link:

(th)

GW Johnson · 2025-03-07 10:16:01

From AIAA’s “Daily Launch” for Friday 3-7-2025:

AVIATION WEEK NETWORK
B-21 Needs Faster Fuel Transfer From Air Refuelers

Northrop Grumman’s B-21 Raider needs a faster gas pump in the sky when it goes into service, a top U.S. Air Force mobility leader said on March 5. The stealthy Raider needs to top off its gas tanks faster than the fuel transfer rates of the Air Force’s current aerial refuelers allow, Gen. Randall Reed, Transportation Command chief, told the Senate Armed Services Committee during a hearing.

My take on the B-21 refuel: it uses fuel faster than they can put it in. Not a good place to be! And the new tanker based on the 737 does not yet function correctly as a tanker! -- GW

NEW YORK TIMES
SpaceX’s Starship Rocket Disrupts Florida Airports With Unsuccessful Test Flight

Starship — the huge spacecraft that Elon Musk says will one day take people to Mars — failed during its latest test flight on Thursday when its upper stage exploded in space, raining debris and disrupting air traffic at airports from Florida to Pennsylvania. It was the second consecutive test flight of the most powerful rocket ever built where the upper-stage spacecraft malfunctioned. It started spinning out of control after several engines went out and then lost contact with mission control.

My take: disrupting air traffic if debris falls is part of the FAA-approved launch license. Sometimes crap ha[ppens, and you have to plan effectively for it. -- GW

AEROSPACE AMERICA
Latest commercial moon spacecraft makes troubled landing

A lunar lander that’s about as tall as a giraffe touched down on a lunar plateau around 12:30 p.m. Eastern time today, but exchanges among staff at the manufacturer’s command center showed that it experienced technical issues, and its status on the surface was left unclear when the internet broadcast ended.

SPACE
Hope is all but lost for private asteroid probe in deep space — 'the chance of talking with Odin is minimal'

The first-ever private asteroid mission appears to be over, just a week or so after it left the ground. California startup AstroForge launched its Odin spacecraft on Feb. 26, on the same SpaceX Falcon 9 rocket that sent Intuitive Machines' IM-2 mission toward the moon. Odin ran into trouble just a few hours later, however, and AstroForge has pretty much given up hope of recovering the 265-pound (120-kilogram) probe.

tahanson43206 · Yesterday 13:12:38

For GW Johnson re POGO and related issues in rocket flight...

You have written in detail, but I could not find articles other than this one with the word POGO...

The subject is of current interest due to the efforts of SpaceX to reach orbit with their Starship vehicle.

GW Johnson wrote:

Thrust oscillations in solids are less objectionable if their thrust contribution is not 100% of first stage/liftoff thrust. Actually, periodic thrust oscillations in a solid are symptomatic of unresolved combustion instability. They interact with mechanical structural oscillation modes in the vehicle, producing (usually) the pogo instability that threatens vehicle breakup.
Pogo can happen without solids, as in Saturn V early on, but solids can be really good at provoking it. That Ares 1 "stick" configuration was really bad for pogo problems, because (1) 100% of the liftoff thrust was solid, (2) it was a long narrow structure subject to pogo, and (3) the stretched 5-segment shuttle SRB design proved to be really hard to tame, as regards combustion instabilities.
This was in spite of being 20% aluminized, which is about the max tolerable metal content. Metals usually help damp the instability tendencies. That kind of periodic thrust oscillation simply wasn't tolerated in tactical solid designs, and we at the plant where I once worked would never let a product like that out the door. Our stuff burned "smooth", only random combustion noise, not organized oscillations.
Aluminized, non-metallized, we just did the job right in development testing and redesign. Expensive up front, but well worth it in the longer run. Part of our better-than-1/million failure rates, sometimes far better.
GW

I'm not sure where i saw this explanation, but I'll toss it in here in case anyone might care to add perspective:

Qualification: This is for a liquid fueled rocket, and not for a solid one.

POGO is (reported to be caused) by variations in thrust/pressure created in a running rocket engine.

It appears it may not be possible to prevent variations in thrust produced by a chemical rocket engine.

As I understand the situation, variations in thrust in the combustion chamber are communicated back to the feed lines from the turbo pumps and (apparently) these changes in pressure can cause changes in the rate of delivery of propellant. Apparently these can become positive feedback loops unless engineers take counter measures.

You (GW Johnson) (and others) have written about different frequencies of oscillation of structures (such as rockets) and how those must be managed by engineers to avoid destructive magnification of forces due to converging oscillations.

The folks at SpaceX are showing the world how to deal with the dynamic forces at work.

In the present moment, SpaceX engineers are attempting to deal with the forces at work in flight of one of the largest rockets ever attempted.

(th)

GW Johnson · Yesterday 18:56:20

I posted about POGO in the "interplanetary transportation" topic, "starship is go" thread. I found a decent Wikipedia article about POGO while researching which Saturn-5 flights had POGO problems. The article quoted George Mueller (formerly of NASA) as saying it's some sort of thrust oscillation in the engines that starts this. The article quotes him as saying it's some sort of "combustion instability". That frequency of oscillation can interact with longitudinal structural modes, and with organ-pipe resonances in the feed plumbing, as a sort of pressure difference thing affecting propellant flow rate. I presume some liquid slosh modes in the tanks could affect this as well, as they would oscillate the feed pressure into the propellant feed plumbing.

The article indicates the unmanned Apollo-6 test of an Apollo-Saturn-5 suffered severe first stage POGO issues that fatally compromised the mission by damaging the second and third stages. The Apollo-13 second stage suffered POGO severe enough to shut one of the five second stage engines down. The other 4 burned longer, as did the 3rd stage, to compensate. This difficulty, which came close to an abort, was overshadowed by the oxygen tank explosion that crippled the craft and forced the emergency abort home.

The article also explicitly mentioned that man-rating the Titan-2 booster for Gemini was delayed because of POGO difficulties in the Titan-2. The article didn't say, but I seem to remember some Titan-2's blew up from this problem, as they were being tested during the Mercury flights.

Combustion instability in a solid is a little different, being usually "something" that causes a pressure oscillation that affects burn rate. If these phase "correctly", the oscillation can grow, raising average pressure, until the motor bursts. Reduced and min smoke solid motors suffer more from this. Smoky motors with aluminum in their propellant see a significant oscillation-damping effect from the inertia of the metal oxide particles resisting the oscillation by their aerodynamic drag in the chamber gases. Those are orders of magnitude larger than the soot particles.

Combustion instability in a ramjet is different yet. Usually it has to do with vortices being shed from something solid. When the vortex detaches, it then "sucks in" the surrounding gas from the region into which it travels as it spins. A fuel-rich vortex "sucking in" air-with-oxygen then ignites and explodes. If the pressure wave from that explosion causes an enhanced rate of such vortex shedding, you have the necessary unstable positive feedback of energy for instability.

But these all share the same characteristics: there is random combustion noise with a very broad spectrum of frequencies. Its pressure amplitude is usually nearer 1-2% of the basic pressure level. Where the oscillation frequency matches some resonant mode in the chamber or associated passages, you will see those pulses of higher amplitude with a definite frequency you can measure, on a pressure-time trace, if you have the right equipment to see it. It will stand out above the "background" noise. There can be multiple modes resonating, more than just one is common, actually. The are usually fundamental modes or first octave modes, of the many resonant modes the chamber shape might have. Noise at 10%-or-more of basic pressure level, we deemed to be "instability" requiring remediation. Which was usually a complete redesign.

You will NOT be able to see these phenomena in situations where the signals are acquired with digital data acquisition, because nobody can afford to buy the equipment that has the requisite 1 Megahertz-or-higher response band! As a result, you need to record the pressure with an analog tape machine based on FM data processing, that has 1 MHz response or better. Then you can play the test record back and plot it in multiple different formats, until you actually see what you are looking for. Digital will never do that, it is too pixelated. But FM tape recorders are old-time equipment that few outfits have anymore, and even fewer outfits would have employees knowledgeable about it, even if they bought some. You really have to know what you are doing, to diagnose combustion instabilities with such stuff. I used to do it all the time. It takes a lot of experience to get it "right" every time! Much more art than science.

We would parallel-feed our test firing data to both digital data acquisition and the FM tape recorder, making both records at the same time during the test, but only during my second tour a the rocket shop! My first tour, FM tape and real-time photo paper galvanometer oscillographs were all we had. The FM tape data recording is like the 5000 frame/second movie footage: if you have it, you can figure out what happened from a bad test. If you don't, you cannot. Guesses about this stuff are usually wrong!

GW

Last edited by GW Johnson (Yesterday 19:16:28)

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