GW Johnson Postings and @Exrocketman1 YouTube videos

tahanson43206 · 2025-05-03 15:00:20

GW Johnson sent a pdf study for the Solar Rocket project. The pdf consists of images.

https://www.dropbox.com/scl/fi/56wex2tj … kdlh8&dl=0

(th)

tahanson43206 · 2025-05-04 15:23:38

GW is working on orbital refueling. He's published a number of concepts.

Here is the latest:

(th)

tahanson43206 · 2025-05-14 07:39:56

For GW Johnson re difficulty of finding work by a forum author...

The default design of the forum software did not anticipate the need that I see, for a way to find particular work by particular authors on the platform.

Let's think about the possibility of creating an index to your work here, comparable to the index you create periodically for your work in the exRocketman blog.

If we decide to create such an index, a logical category would be this category (Meta New Mars) and it might have a title like:

Index to posts by GW Johnson (or something similar)

In order for this to make sense, the posts in that topic should be owned by you, so you can update them as needed.

(th)

GW Johnson · 2025-05-14 08:32:35

I guess I do not understand clearly what the words refer to.

Never having used the forum's search tool, I cannot say, but I would think it should locate everything a user posted, if you search for his username.

Does it not do that?

GW

tahanson43206 · 2025-05-18 09:26:42

For GW Johnson re post in FR-TSTO topic...

First, thanks for your contribution to the topic:
http://newmars.com/forums/viewtopic.php … 60#p231760

I'd like to point something out that one or two of our readers may be missing....

Once full reusability is achieved, the only cost of flight (not considering the business expenses that are the same for all businesses) is fuel. At that point, the amount of payload you can get to LEO is not important, except in terms of how many flights you book for your particular use case.

At that point, the decision is based upon the size of the vehicle, just as it is in the aeronautics industry.

(th)

RGClark · 2025-05-18 16:44:48

tahanson43206 wrote:

For GW Johnson...
RGClark just opened a new topic about an Italian company that is (apparently) planning to use a rocket fuel that produces a greater ISP than any rocket created by humans to this point.
My recollection is that among your many publications is one that shows that an ISP greater that 450 can produce desirable results.
If you have a moment or two, please add a post to RGClark's new topic.
Please don't say that the new rocket is not possible with known technology, because clearly the company will be using technology that is new and far beyond anything achieved in the past several thousand years.
Instead, please show what the ISP of the new rocket fuel must be to achieve the desired result.
I assume the ISP must be greater than 450, but perhaps no more than 650?
(th)

I did a search of “RGClark” on the forum, to find posts I hadn’t seen and saw this. I don’t remember it. Perhaps you mean Sidereus that want’s to make a small SSTO:

Sidereus Space Dynamics Complete Integrated Static Fire Test.
https://europeanspaceflight.com/sidereu … fire-test/

Bob Clark

tahanson43206 · 2025-05-21 11:34:28

For All...

This post is to mark a step taken by GW Johnson to register a claim for a possible solution for challenges of on-orbit refueling. A series of documents were submitted today to the US Patent Office web site, in accordance with requirements for this type of application, and the fee was paid.

I am hoping this set of documents will become public, and when that happens I'll post the links so NewMars members can see the claim.

Please note that the intellectual property claimed may already be covered in an existing patent, or in a patent application that is pending, but it costs thousands of dollars to find out.

***
Update: GW Johnson clarified that the documentation he filed is NOT made available, unless and until it becomes part of a full application. GW has one year from today to complete a full application, with the assurance the documents he filed today will show primacy if a search does not turn up prior art, or a patent pending that covers the IP.

GW will be working on a presentation for prospective investors, so we might be able to see that at some point.

(th)

tahanson43206 · 2025-05-23 06:16:48

This post is to report on further developments building upon GW's registry of a concept for his on-orbit refueling depot with the US Patent Office. He completed a set of elements for a presentation at a conference (slides, text, images).

There are plenty of space related conferences, including the Mars Society in October (9-11) of 2025.

Suggestions of conferences by NewMars members are welcome.

I'll report more news as it becomes available.

(th)

tahanson43206 · 2025-05-28 11:04:53

For GW Johnson re comments on Flight Test 9

Thanks for your perspective on the flight and recommendation(s) for improvements.

In your post, you indicated the possibility the booster may have lit three center engines to provide ullage to insure propellant stayed at the bottom of the tank after Starship departed.

This post is to confirm that those center three engines did indeed light, if the digital readout can be trusted.

I thought at the time that this must be part of the planned activity to improve chances of success of the Hot staging maneuver.

Your observations about the Angle of Attack planned increase are helpful. It occurs to me that the design team may be looking at the point of failure of the air frame, to see if it can be strengthened. I would assume there must be tradeoffs at work, to improve the reusability of the Super Heavy. Perhaps a steeper AOA would mean a faster return to the launch point, and thus perhaps less fuel for the return, as a tradeoff for increased mass of the air frame?

(th)

GW Johnson · 2025-05-28 19:02:45

The idea behind high AOA during booster entry is that high AOA flight is higher drag that acts to decelerate you. That reduces the propellant quantity required for the landing burn. The problem is that high AOA is a high crossflow velocity with larger wind loads perpendicular to the stage axis. Every supersonic airframe I ever heard of would break up under those crossflow air loads in supersonic flight, if there was more than trivial ambient atmospheric density. Higher AOA is higher breakup risk. Simple as that.

GW

GW Johnson · 2025-05-29 08:33:58

Found this in today's AIAA "Daily Launch" email newsletter:

----------
article image
Aviation Week Network

Space Ops: Blue Origin Prepares To Leapfrog SpaceX To The Moon

Blue Origin plans to attempt a lunar landing this year. If successful, the MK1, which is 26 ft. tall and 10 ft. in diameter, would become the largest vehicle to touch down on the surface of the Moon, eclipsing the Apollo program’s Lunar Modules (LM) that landed crews six times in 1969-72. Fully fueled, the MK1 weighs 47,000 lb., compared with the 36,200-lb. mass of the extended Apollo LM.
-----------

We will soon see if it works. Between the larger size, and the hydrogen fuel, that is how the Blue Origin lander can do the landing single stage, even from that ridiculous Gateway orbit with the one-way dV that is at least factor 1.5 larger than Apollo's.

Meanwhile, SpaceX is getting into trouble with its basic design approaches, and I'm unsure they actually realize it. Had they had attitude thrusters independent of propellant tank pressurization, Flight 9 might have been under control at reentry! Simple as that! Between Flights 7 and 8, that answer has been staring them in the face.

GW

GW Johnson · 2025-05-29 08:36:29

From the same issue of Daily Launch" as the previous post:

------
SpaceX Starship failure casts further doubt on NASA’s moon landing timeline

NASA hopes to put astronauts on the moon in just two years, but a critical spacecraft required for the mission keeps exploding or disintegrating: SpaceX’s Starship, the largest rocket ever built. Originally envisioned as a Mars rocket, it is also a key piece of NASA’s plan to outpace China and land humans on the lunar surface for the first time in more than half a century.
------
Just goes to show that resolving this is a very serious issue, despite all the chaos released upon NASA by that crowd in DC.

GW

tahanson43206 · 2025-05-31 17:59:45

This post is offered to try to encourage further development of ideas in the Starship is Go topic...

The 10 Hertz oscillation is NOT being observed in a 50 meter long ship.

The 10 Hertz oscillation ** is ** being observed in the test facility in McGregor, Texas.

Could there be resonate piping at McGregor?

(th)

GW Johnson · 2025-05-31 22:08:19

You completely missed my points.

There is some kind of 10 Hz pressure oscillation in the engine chamber. I can feel those effects from 6 miles away, and they are there whether or not there is any sort of plumbing around the engine.

In the ship, but not the test stand in McGregor, there are particular forms of plumbing that might be susceptible to being driven by that 10 Hz oscillation in engine pressure, via the mechanical shaking of the engine in its mountings in the stage. That is because of the lengths of feed piping in the ship (that are not there at McGregor). You have to pipe propellants from the tanks to the engines. One of the header tanks has been in the nose, almost 50 meters away. The lengths are there to hit one of the first couple of harmonics to that 10 Hz oscillation.

If the plumbing responds to the 10 Hz shake by its contained fluid resonating with it, that could affect the propellant flow, which literally is the energy release rate in the chamber, so there is the possibility that there could be an energy feedback from engine to plumbing and back to engine. The engine shake drives a wave in the plumbing, which affects flow rate, which increases the intensity of the vortex shedding oscillations in the chamber. If the wave in the plumbing gets strong enough, the pressure nodes of it it break a tube or a fitting somewhere. And THAT effect is exactly what they have been describing with their talk about oscillations and fuel leaks.

It does not matter one tinker's damn that there is no ship or ship-like plumbing at the McGregor test stands! The initiating oscillation in the engine is still there! Which is what I have been feeling from all three versions of Raptor. There is nothing outside the engine for it to interact with. Put the engine in the ship, and there is.

Merlin does not seem have this problem with pressure oscillations in its chamber, at least not at a strength that I can observe. But it burns kerosene, not methane! That's inherently a sooty flame, and that soot cloud is a draggy inertia on the gas oscillations, acting to damp them down. So, even if the propellant injection geometry is identical in both engines, and so cause the same exploding-vortex shedding, the two engines are just not very likely to respond in the same way, as one has a damping cloud in it, the other does not. Methane burns virtually soot-free.

GW

Last edited by GW Johnson (2025-05-31 22:16:18)

SpaceNut · 2025-06-01 16:33:07

I started to look at the test stand as one place that is largely different than a starship in flight.

tahanson43206 · 2025-06-05 09:22:32

For GW Johnson re image of kbd512's ITV with dual rotating batons...

The early NASA study that kbd512 found to illustrate the baton concept featured braces to protect the booms from stress caused by propulsion forces.

Without protection the booms will snap off at the base.

G forces that may be exerted could reach as high as 3 during normal operation, and special circumstances may cause even greater acceleration.

The habitat booms can be protected with light weight cables, provided that the booms are separated by enough distance.

At this point I do not know what the effect of separating the counter-rotating batons might be on the operation of the space craft.

This topic (GW Johnson) is not limited to any particular technology or subject, so a study of gyroscopic effects in microgravity would be a welcome addition to the NewMars archive.

A simple test instrument could be created to fly on the ISS, to investigate the behavior of a system consisting of a non-rotating shaft with two counter rotating batons that can be mounted at various locations on the shaft. The test instrument could be equipped with battery powered motors to turn the batons at various rates. An ISS researcher could perform experiments such as pushing the end of the central shaft to see what effect longitudinal acceleration has on the system.

The same experiment could be performed on a parabolic flight, but the duration of the experiment would necessarily be less.

(th)

tahanson43206 · 2025-06-09 06:54:16

For GW Johnson re link in one of Void's posts:
https://newmars.com/forums/viewtopic.ph … 17#p232117

Void provided us a link to a presentation by Angry Astronaut about a nuclear thermal rocket.

About half way through the presentation, AA provides an animated graphic on the Hohmann Transfer. I am curious about the graphic and would appreciate your opinion. It seems to me the graphic fails to account for the difference in velocity of Mars with respect to the arriving vessel. As I view the animation, I get the impression the person who created the graphic was unaware of the difference in velocity of the vessel as it reached the apogee of the Hohmann Transfer ellipse, and the velocity of Mars in it's orbital ellipse.

In many posts, you have given that velocity as a not insignificant value in km/s. In addition, you have mentioned the acceleration of Mars as it acts upon the vessel, to accelerate the vessel toward Mars. What I don't recall is whether the gravity of Mars might be enlisted to help the arriving vessel to catch up to Mars as it approaches from behind the vessel?

(th)

GW Johnson · 2025-06-09 15:56:03

He did not seem to realize that the spacecraft as it reaches Mars's orbit, is moving slower than Mars. He said it was moving faster, and that is entirely wrong. Mars literally runs over you from behind! All these speeds are with respect to the sun.

Him saying you have to slow down to arrive at Mars was correct, although I believe his understanding of that is flawed. There is a change of coordinates involved, before you can determine speed relative to Mars instead of the sun. Your speed with respect to the sun, minus Mars's speed with respect to the sun, is your relative speed with respect to Mars. That will be a negative number, because Mars is faster.

Doesn't matter, that difference is BEFORE the effect of Mars's gravity accelerates you toward the planet to an even higher speed relative to Mars (still a negative number). The negative numbers do not matter, when you square them to compute kinetic energy. That's what my little correction equation for "Vnear" vs "Vfar" does. And that higher speed close-in is what you have to "kill" to one extent or another, either to land directly, or to go into orbit about Mars.

Off of Hohmann, that Vnear higher speed is actually a little above Mars surface escape, at about 5.4 km/s (escape 5.0 km/s). Off a faster trajectory, it is higher still, and requires vector math to compute, since the orbit arrival point is not a collinear tangency, but a crossing at some significant angle. Off the 2-year abort ellipse, it is closer to 7.4 km/s.

Since Mars is literally running over you from behind for a Hohmann transfer, you cannot use its gravity to "catch up the planet", it is catching up to you (!!!), and it is pulling you in ever faster as it tries to run over you from behind.

GW

Last edited by GW Johnson (2025-06-09 15:56:29)

GW Johnson · 2025-06-09 16:08:05

The liquid core nuclear thermal concept is not at all new. It dates back to the late 1950's, as does the two gas core concepts. All these got a little bit of design work, based on presumptions, not hard data. What little experimental work there was, was academic-type bench testing. No engine test articles were ever built.

Actually, the open-cycle gas core nuclear thermal engine might actually be an easier problem to solve. The bench tests confirmed a reactor core in the gas phase could be controlled, and a couple of flow schemes tested as plasma devices showed that the hydrogen/uranium flow rate ratio could be near 1000:1, which was effectively as good as "perfect containment", due to burnup time being about the same order of magnitude as the uranium residence time. There would be hard radiation in the plume, composed of nuclear reaction products. The Isp was estimated as around 2500 s, with simple regenerative cooling, which led to a really good-looking estimated thrust/weight for the whole engine system.

The other gas core concept was the "nuclear light bulb", which had a double quartz wall between the uranium fireball and the hydrogen to be heated. The hydrogen flowed between the quartz walls to cool them, before finishing its heatup outside the wall. This was estimated as 1300-1500 s Isp, and a thrust to weight looking only slightly better than solid core. It could theoretically have a plume free of radiation, but you'd have to do something about the products accumulating in the gas core. No one ever figured that difficulty out. .

GW

Last edited by GW Johnson (2025-06-09 16:11:03)

tahanson43206 · 2025-06-11 19:43:57

The pdf at the link below contains a five page study on Transfer Orbits in images with words to explain the diagrams.

https://www.dropbox.com/scl/fi/rbcd3k9l … fgwx8&dl=0

(th)

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#526 2025-05-03 15:00:20

Re: GW Johnson Postings and @Exrocketman1 YouTube videos

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