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#1 2022-01-12 11:42:40

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 11,960

GW Johnson Postings

This new topic is opened to (try to) provide a convenient access point for work of GW Johnson that resides outside the NewMars forum database.

That said, this topic is ** also ** an excellent place for NewMars members to post comments about any of the many posts already in the database.

Update 2022/01/13: Dropbox allows sharing of files in view mode and edit mode.

Some files (such as Microsoft and Google) default to edit mode.  It should be possible to change to view mode, but the drop down list to do that does not necessarily appear.

Here is an example of a file link that is edit mode:

<removed>/<removed>.docx?dl=0&rlkey=c6qlttsbmb9b3jvuwpnna97yw[/u r l]

A view only link stops at dl=0 

Accordingly, I am guessing that it will be possible to make the links view only by removing the key= parameter.

In addition, I subsequently learned that giving Dropbox a bit of time to settle files into it's structure helps to make the View choice available.  In addition to ** that ** I found that Dropbox tries to help by remembering what the operator did last time, so that if "Edit" was the choice then that may show up next time a file is to be linked and shared.  In that case, persisting with the Share button ** may ** free up the dropdown list to reveal the View Only option, which is what is needed for most of the offerings in this topic.

Update 2022/02/10 Ahead of a scheduled presentation on April 9th, for the North Houston chapter of National Space Society, GW Johnson provided this short biography for the meeting advertisement/banner:

"Gary W. Johnson is a lifelong engineer and teacher,  now retired.  He had two 20-year careers,  the first in aerospace/defense new product development,  the second in mostly teaching but with a little civil engineering.  He is a long-time registered State of Texas professional engineer,  but is now inactive,  being retired. 

The defense products included missiles and a launch vehicle,  rocket motors,  ramjet engines,  and some aircraft and ICBM decoy work.  The teaching career spanned the levels from 7th grade math to graduate-level strength of materials,  in math,  physics,  and engineering.  The civil engineering included fire protection systems,  foundation inspection and design,  water and wastewater permitting,  spill cleanups,  and hazardous material identification and disposal. 

He went to work decades ago with BS and MS degrees in aerospace engineering when slide rules were the "calculator" everybody was using,  and added a PhD late in life in general engineering.  He has extensive experience with alternative fuels in aircraft and in ground vehicles and equipment,  plus experience obtaining supplemental type certificates with the FAA for some of the aircraft alternative fuel work.  He studied manufacturing and production for his doctorate,  but did his dissertation on alternate fuels in piston-engine aircraft.

He and wife Ellen (also retired,  a former nurse) have one son (James) now grown,  and live on an old farm near McGregor,  Texas,  which he named "the Idea Farm".  There he invented,  patented,  builds,  and sells custom farm implements that eradicate prickly pear cactus from farm and ranch pastures."

GW

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#2 2022-01-12 11:44:35

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

2022/01/12

Edited 2022/01/20

GW Johnson has created many documents that are available for public viewing, and he has a number more in the queue.

NewMars has recently opened a permanent storage location for files, and this post is intended to provide a link to four of them.

2022/01/12 at 14:47 local time ... trying again to post links to files of GW Johnson stored on NewMars Dropbox.

Links that end in dl=0 appear to provide view access to the public.


This Link is for those who are running Windows Excel:
orbits.xlsx  Ths is the Windows version of Orbits

https://www.dropbox.com/s/5z6r7fqmpfuz4 … .xlsx?dl=0

This link is for those who have Open Office installed (eg, Linux, Apple) users link:
orbits GW Johnson 20210205 odf.ods

https://www.dropbox.com/s/txkop1eqw8rn2 … f.ods?dl=0

User manual link:

The pdf file "user manual" is the user's manual I wrote for the spreadsheet "orbits".  It has a writeup for each worksheet telling what that worksheet is and does,  and how to use it. 

GW

User Manual for Excel Spreadsheet Orbits pdf

https://www.dropbox.com/s/j9glviv3r810k … f.pdf?dl=0

Pdf link:
Generic Propulsion Comparison 20220106.pdf

https://www.dropbox.com/s/yp32szwgf2byx … 6.pdf?dl=0


Image link:
tug depart.png

https://www.dropbox.com/s/hap1tv0odtjsg … t.png?dl=0

If GW Johnson requests that additional information be added, this post will be updated.

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#3 2022-01-13 10:09:34

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is intended to hold links to the latest set of files provided by GW Johnson for reference, and for education, or for use in service.

There may be some overlap with the files linked in Post #1 of this series.

Hohmann transfer:
https://www.dropbox.com/s/e5kfmochtvvb9 … 6.png?dl=0

Generic propulsion pdf: Generic Propulsion Comparison 20220111.pdf
https://www.dropbox.com/s/vgchslch21umi … 1.pdf?dl=0

Several files are not linked in this work session, because Dropbox offered the links for editing, and i could not see a way to change the permissions to view only.

Update at 11:30 local time ... I checked the Community database, and did not find an answer, except a clue that the Professional version of Dropbox offers more control options.   Then, I looked at the link, and observed that the edit version differs from the view version by the addition of a 'key=' parameter.  I'll try deleting the key parameter to see if that helps.

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#4 2022-01-14 07:07:46

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

In this post, I will attempt to set up links to GW Johnson files not yet linked.

Some overlap with previous posts may occur.

This first link is for Big Ship Stuff. This version is for Windows users who run Excel.
https://www.dropbox.com/s/gs4vofq77xjvo … .xlsx?dl=0

Available Powerpoint Slidesets:
>> this link needs to be updated to pdf format
PowerPoint%20Slidesets%2020220111.docx

Spreadsheets with User Manuals:
>> this link needs to be updated to pdf format
Spreadsheets%20with%20User%20Manuals%2020220111

User Manual for Spreadsheet Orbits in Open Office format:
>> this link needs to be updated to pdf format
User%20Manual%20for%20Excel%20Spreadsheet%20Orbits%20odf.odt

User Manual for Spreadsheet orbits in Microsoft format:
>> this link needs to be updated to pdf format
User%20Manual%20for%20Excel%20Spreadsheet%20Orbits.docx

The Orbits spreadsheet links are in previous posts.

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#5 2022-01-16 08:32:52

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is set up to contain work done by GW Johnson for EVA suits:

The first link is to a Microsoft Word version.  I will attempt to provide a pdf version.

>> this link needs to be updated to pdf version
20220116%20Min%20Suit%20Design.docx?dl=0

Added later:

20220116 Min Suit Design pdf
https://www.dropbox.com/s/pu8t12q6kcz9b … f.pdf?dl=0


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#6 2022-01-19 13:13:44

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is a follow up to #5

It provides a link to a power point presentation, rendered in pdf format, and to a set of notes, also in pdf format.

Here is the Power Point presentation:
https://www.dropbox.com/s/y08gsgmefhdma … f.pdf?dl=0

And here are the notes:
https://www.dropbox.com/s/upnuhnsbybj5l … m.pdf?dl=0

For all: Please confirm these links work for you.

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#7 2022-01-19 19:58:10

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,951
Website

Re: GW Johnson Postings

Tom:

I can now see everything you have posted.  Including the illustrations.  It looks great.  This is the first time I have seen the illustrations.  Even the Powerpoint looks great. 

No idea how you did it,  but you did it!  Congrats!

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#8 2022-01-19 20:20:48

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,734

Re: GW Johnson Postings

The level of documents and content are quite good for instruction lessons to follow.

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#9 2022-01-27 19:16:22

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is to hold a link to a document that contains a summary of files available from GW Johnson.

If a file listed is not available, or you can't find it, please post an inquiry. 

20220126 Spreadsheets with User Manuals pdf.pdf

https://www.dropbox.com/s/35rniv9leowis … f.pdf?dl=0

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#10 2022-01-29 10:36:54

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is set up to hold links to two files to support a presentation ...

Links will be added later, after the files are copied into the NewMars Dropbox repository.

SearchTerm:Presentation GW Johnson Propulsion Big Ship Plus Tug Pusher flight plans

Presentation Slides
https://www.dropbox.com/s/kgdlsm0soxf5e … F.pdf?dl=0

Presentation Notes
https://www.dropbox.com/s/4hcnfzx31nlk2 … s.pdf?dl=0

SpaceNut provided links to Mars Society activities for an introduction to the Mars Society ahead of the presentation.

SpaceNut wrote:

Nice to hear that the hard work is paying off with Green screens.

MDRS does have lots of great images

https://mdrs.marssociety.org/category/crew-photos/

image searchhttps://pbs.twimg.com/media/Ds-BgoqUUAA-dqw?format=jpg&name=small


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#11 2022-02-04 10:58:49

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

We (GW Johnson) was offered a (possible) date of April 9th for a presentation on Orbital Mechanics to be given to the North Houston chapter of the National Space Society. 

Dr. Johnson will be coaching me through presentation of slides on Zoom, at 2 PM Houston time tomorrow, Saturday the 5th of February.

That time is 8 PM UTC, and just barely reasonable for our members in Europe.

If anyone (Europe, US, Canada, Mexico) would like to join the feedback audience for the "dress rehearsal" tomorrow, please post a note in the Zoom topic, or here if that is more convenient.

Anyone not already checked out with the access codes needs to request them.  They will be delivered by email, using the account you have specified in your membership record.

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#12 2022-02-27 17:44:50

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

20220227 Zoom Document for discussion

This is a draft of ongoing work.

Dr. Johnson asked that it be made available for participants in tonights Early (US/Canada/Mexico) Zoom at 1 AM Monday UTC.

https://www.dropbox.com/s/uu6yqw5cuqe5s … f.pdf?dl=0

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#13 2022-02-28 18:48:57

tahanson43206
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Posts: 11,960

Re: GW Johnson Postings

20220228 Update of Large Ship Propulsion computations by GW Johnson

https://www.dropbox.com/s/ugk8gwace5tln … f.pdf?dl=0

This document is updated compared to the one published 2022/02/27

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#14 2022-03-02 11:03:55

tahanson43206
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Posts: 11,960

Re: GW Johnson Postings

20220301 Update of Large Ship Propulsion study by GW Johnson

An updated (and close to finished) version of the propulsion study by GW Johnson is in transit.

When delivered, this post will contain a link to a pdf file stored in the NewMars dropbox.

https://www.dropbox.com/s/vgvczlmdwjrd4 … t.pdf?dl=0

All members are invited to test this link, and to make comments or ask questions.  Please choose a topic other than this one for comments or questions.

This topic is intended to contain links to work done by GW Johnson, or to comments about posts he has created in the forum.

The distinction I am trying to make may not be clear.  This topic is for comments about posts.

Contributions about materials ** referred to ** by posts should go in topics set up for the subjects at hand.

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#15 2022-03-05 20:03:11

tahanson43206
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Posts: 11,960

Re: GW Johnson Postings

This post provides access to a two page summary to help with understanding of flight planning ...

https://www.dropbox.com/s/yjqq2b02xgow9 … f.pdf?dl=0

Big Ship Analyses Fundamentals

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#16 2022-03-06 14:30:34

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is intended to hold copies of two documents GW Johnson requested be made available for tonight's Zoom.

PowerPoint:
https://www.dropbox.com/s/k0sfnta7yjw3c … f.pdf?dl=0

Notes:
https://www.dropbox.com/s/hvjabph03n8ns … f.pdf?dl=0
Notes:

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#17 2022-03-11 11:18:33

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post brings two new files to NewMars ...

The first is an update of the PowerPoint presentation for April 9th.  Numbers have been added to help the audience to refer back to particular slides.
https://www.dropbox.com/s/mxrw2rxmew40f … f.pdf?dl=0

The second is a new study of NERVA.
https://www.dropbox.com/s/ibk8d6a03m6wm … f.pdf?dl=0
***
I'm bringing the Presentation notes forward so they are here with the new PowerPoint slides.

Presentation Notes to go with PowerPoint presentation for April 9th.
https://www.dropbox.com/s/4hcnfzx31nlk2 … s.pdf?dl=0


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#18 2022-03-18 11:22:34

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post brings two new files to NewMars

Both are studies of the Large Ship propulsion problem..


https://www.dropbox.com/s/ba6k9vdnd2mg6 … f.pdf?dl=0


No-Infrastructure-On-Mars Scenario                        GWJ    3-17-2022
The purpose is to quantify vehicle sizes and propellant requirements for a “big ship” orbit-to-orbit transport between Earth and Mars,  with no propellant manufacturing capability in place on Mars for refilling on-orbit there.  The “big ship” is modeled as a dead-head payload item of 5000 metric tons.  The propulsion is liquid oxygen/liquid methane at 380 s specific impulse in vacuum.  The mission is to fly from low Earth orbit to low Mars orbit,  with a tug assist and elliptic capture orbit only at Earth.  The “big ship” propulsion module must make the round trip unrefilled at Mars.  See Fig. 1.

https://www.dropbox.com/s/xzwfmt48jmid2 … f.pdf?dl=0

Worst Case Scenario                            GWJ        3-17-2022
The worst case scenario for chemical propulsion is to attempt the round trip orbit-to-orbit,  single stage,  unrefilled at Mars,  and without any tug assistance at either planet.  See Figure 1.

NewMars members (and forum readers) have an opportunity to study the documents that will be presented (in part) at the April 9th meeting of the North Houston chapter of the National Space Society.

I would like to express my thanks to Dr. Johnson for doing the many hours of work needed to provide the audience with a sense of what it will take to move 1060 passengers and  crew safely from Earth to Mars and back.

The studies include chemical propulsion and alternative forms of propulsion that do not exist, but which are plausible.

Since I am interested in pricing out the entire project, and I am dependent upon existing technology, I appreciate Dr. Johnson making several studies of the chemical scenario that he would not otherwise have undertaken.

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#19 2022-03-19 13:35:13

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

Today Dr. Johnson provides an overview of all the options, in a single 9 page document:

https://www.dropbox.com/s/mbl1yckf368qi … f.pdf?dl=0

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#20 2022-03-20 08:31:34

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

The North Houston chapter of National Space Society requested a link to Dr. Johnson's "magic" spreadsheet...

There are multiple copies, so we can expect an update when Dr. Johnson has time to help me out ...

In the meantime, here is a link that appears to be in the ballpark:

This first link is for Big Ship Stuff. This version is for Windows users who run Excel.
... to be replaced ... first link was damaged

Update at 13:57 local time.... here is another copy/version of the spreadsheet, left in xlsx format.
https://www.dropbox.com/s/s94radzahyllz … .xlsx?dl=0

SearchTerm:Magic Spreadsheet
SearchTerm:Spreadsheet Magic

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#21 2022-03-20 16:31:58

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

Dr. Johnson has completed two more files for review by anyone who might have the time ... these are part of the complete series intended for the April 9th presentation.

First is an update of the Powerpoint Presentation, rendered in pdf format.

To experience normal pagination, I've found that Adobe Acrobat is helful...

https://www.dropbox.com/s/tsdutoj9rmdma … 3.pdf?dl=0

The next is ...

https://www.dropbox.com/s/k75cv2e17bdlc … f.pdf?dl=0

This is another (updated) view of the entire set of studies....

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#22 2022-03-27 18:39:41

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

Ahead of this evening's Zoom meeting, Dr. Johnson put together a document and two images to review the full suite of chemical propulsion options, less one.

I think I have created what you wanted:  a spreadsheet with all the results of all the chemical studies I have run for the big ship.  I simply copied big ship propulsion stage and tug stage propellants from the existing sizing analysis spreadsheet images,  into a new worksheet,  all in one place.  I did this for 2-way unfilled at Mars,  using Hohmann from LEO to LMO and back.  I did it for 2-way unfilled at Mars,  with only an Earth tug.  Then what I had done previously gets added:  1-way refilled at Mars,  no tugs.  Then 1-way refilled at Mars,  Earth tug only.  Then 1-way refilled at Mars,  Earth and Mars tugs.  And last 1-way refilled at Mars,  Mars tug only.  6 cases.

The only way I found so far to get under 2 million ton propellant quantities at Earth is to do some refilling at Mars,  which will require some propellant manufacturing infrastructure there.  The absolute min Mars infrastructure requirement is for 1-way refill at Mars,  with only an Earth tug,  but the Earth propellant quantity is still right at a million tons per mission.  You can essentially halve that Earth quantity by accepting a little bit higher quantity and rate on Mars,  with 1-way refill at Mars plus both Earth and Mars tugs.  The Mars manufacturing min rate is about 1200 metric tons per month,  which is slightly more than an order of magnitude larger than what Spacex faces refilling one Starship for a return home in roughly a year:  100 tons/month.

Attached are the word.docx file in which I put the plotted data,  plus two png files of the raw data that were plotted,  and the plots that I made with it. 

The one thing you've mentioned that I have not looked at,  is sending a tug to mars with all the propellant it needs for one mission,  to refill the big ship on-orbit at Mars.  I don't know,  but that sounds like it may actually raise the total Earth propellant quantity above just sending the big ship 2-way un-refilled at Mars,  with no tugs.  That was about 9 million tons.

I think that,  because I have been saving gobs of propellant by not sending Earth tugs to escape+ speed.    It's not the tug,  it's the tug plus all the propellant it is going to need at Mars.  That's a bunch of mass to push past escape at Earth.  Do you really want me to look at that?

GW

Links to the files will be posted here shortly.

Here is the document: https://www.dropbox.com/s/7itykep3v41ey … f.pdf?dl=0

Here are the images: ... It appears that Dropbox is not set up to host images. The "share" option is not provided.
However, imgur.com should work, so I'll put the images there.

Image 1 of 2: D8sBm6L.png

Image 2 of 2: u8Q8hhf.png


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#23 2022-04-01 15:01:37

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

We have a new document from GW Johnson to study, ahead of the April 9th presentation in Houston!

This one adds the scenario I've been hoping might become available: Tug advanced placement at Mars!

https://www.dropbox.com/s/wo3wmwvfm26k4 … f.pdf?dl=0

In this scenario, the Solar System is opened for exploration by Large Ship (and it's successors).

The careful and exhaustive work by Dr. Johnson shows that an all-chemical solution ** is ** possible, although it certainly does require some effort.

In the scenario just added, a Tug with all the propellant it needs to dock Large Ship at Mars, and ** then ** send it safely on it's way back home, is positioned at Mars to await Large Ship.  The key technology that has ** just ** been demonstrated, that makes this scenario possible, is deep chill (50 Kelvin) as demonstrated by the James Webb engineering team.

This scenario eliminates the entire requirement for propellant manufacture at Mars.

This scenario ** also ** opens the opportunity to visit other Solar System destinations where propellant will not be manufactured in advance of the visit.

We all might hope that nuclear propulsion capabilities will arrive before Large Ship is ready to venture away from LEO, but the all-chemical solutions described by GW Johnson mean that the expeditions ** can ** be mounted, if we (humans) have the get-up-and-go to make it happen.

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#24 2022-04-04 17:57:02

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

Here are three additions to the GW Johnson collection...

There are two files ahead of the presentation in Houston on April 9th.

Overall Results PowerPoint...
https://www.dropbox.com/s/carom7wejxoq3 … f.pdf?dl=0

Version 3 Big Ship Propulsion Studies
https://www.dropbox.com/s/hjkq9x3kvtchg … f.pdf?dl=0



The other is an email that came out of the most recent Zoom meeting, in which construction of the pressure hull for the habitat ring was discussed.

Attached sketch is based on what I understood from the Sun 4-3-22 zoom meeting.  The pieces could be formed by rolls,  continuously from sheet coming out of the foundry,  similar to the way roll-and-weld seamed pipe is rolled,  before welding.  These rolled parts are then cut to 19-20 m lengths from the very long foundry-rolled material as needed.  There's 2 sets of rolls:  one for > 90 deg,  the other for < 90 deg,  by about a deg or 3.  Whatever works out right,  for the inner and outer rings.

The jigs are electromagnetic,  and hold maybe 3 to 5 of these pieces in position for electron beam welding together on orbit.  You keep using the jig to add groups of pieces,  until you have formed a whole ring. 

You join the outer and inner rings by putting the inner inside the outer,  and then using the interior bulkheads as their own spacer jigs for electron beam welding.  Then you add the outer edge pressure wall pieces,  by electron beam welding. 

As it was done down here on Earth in vacuum tanks,  making rocket motor cases,  weld efficiencies of 90-100% were obtained.  Most other types of welding were closer to only 50%.  The difference is the very much smaller heat-affected zone and lower adjacent material temperatures associated with electron beam welding in vacuum.   

Those inner bulkheads which are pressure bulkheads cannot be flat panels,  neither can the outer edge pressure wall pieces!  These will have to be stamped to shape on Earth,  or built-up on Earth.  Flat panels with a pressure difference across them have very large bending stresses,  and will induce very large bending stresses in whatever they are welded to.  Curved panels do not induce nealy so much bending,  even if curved in only 1 dimension (which is why cylindrical motor cases can be so thin).  There does need to be a doubler-type stiffener at the joints to curved end wall or pressure-bulkhead pieces.

GW

zweikLu.png

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#25 2022-04-06 18:22:24

tahanson43206
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Registered: 2018-04-27
Posts: 11,960

Re: GW Johnson Postings

This post is reserved for two files from the ExRocketman blog.

I asked for them because they are directly related to the just-revisited topic on building a service facility for Hubble.

The two files have arrived, and I'll prepare them for display this evening (local time).

On Orbit Repair facility

https://www.dropbox.com/s/0brh2bl79bwqv … f.pdf?dl=0

On Orbit Repair Capability

https://www.dropbox.com/s/qj5oi0dfeza5x … f.pdf?dl=0

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