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GW,
What does your slide rule say about the answer to this problem?
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OK .... ** this ** is interesting.
As I attempted to create the new session, the Professional session resumed with the message ... would you like to reclaim host?
I said yes, and the session resumed
(th)
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The atmospheres I recommend are given on "exrocketman" as the article titled "Suit and Habitat Atmospheres 2018", dated 16 March 2018. For general use, I show atmospheres not far from Rob's numbers, with zero prebreathe time going to a pure oxygen suits. My suit pressures are just a tad under 3 psi. The hab is just about 6.5 psi, but 45% oxygen. Same mass per unit volume concentration as Earthly sea level air, so the fire danger should be equivalent. I did have a about 10.5 psi synthetic air at 21.9% oxygen, for pregnant women. See Figures 7 and 8 in the "exrocketman" article.
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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For GW Johnson ...
If you have not already re-connected, please try the Professional number and passcode again!
Ignore the temporary ID and passcode I tried to set up.
My apologies to everyone for apparently causing the outage.
I set up an audio session, but I used Ubuntu, and I had to download an update. I suspect that something about that procedure caused the outage.
(th)
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Slide rule is silent, Kbd512. Usually is. I'm still getting the same "host has another meeting in progress" error. Unable to reconnect.
Tom: my asteroid deflection column was indeed published in the Waco Tribune-Herald yesterday.
Rob: I can use your ship mass as payload for my rocket performance spreadsheet. Any particular stage-only inert mass fraction you want me to look at?
GW
Last edited by GW Johnson (2021-12-05 20:44:00)
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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At about 8:45 central std time I got back into the zoom meeting. This was after about a dozen unsuccessful attempts. But, I am the only participant there. So, I left the meeting.
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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For GW Johnson re #106
My apologies again for (apparently) causing the disruption of today's meeting!
It was good having you there for the Large Ship discussion! it seems to me (as I watch and listen) that RoberDyck is progressing much more rapidly with the video conference environment than was possible with just forum posts.
Next week I'll just leave the session if I have to, and not disturb anything!
(th)
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For SpaceNut re Zoom session ...
I finished up for the day at midnight local time, and was interested to find RobertDyck and kbd512 still hard at work ... UTC is 05:23:42
(th)
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Then I missed them. Sorry.
About all I have to offer is structural rules of thumb regarding walls that must hold a pressure difference. Flat straight panels are the worst case. The failure mode is bending-induced geometric instability, and it happens at rather low pressure differences. The larger the panel, the lower the difference. Flat bulkheads in ships and submarines are thick parts, with all sorts of reinforcing stiffener members made part of them.
If your pressure wall is part of a curved surface, be it cylindrical or spherical, things get to be very much better. These you can build of thin material and simple geometry, especially if the material is going to be stressed in tension. It still works up to a point when the material is in compression, but you are better off adding some stiffeners to it; in compression, there is geometric instability to contend with. Tension is just stable.
Spherical does not necessarily mean you have to build the whole sphere or hemisphere. You can do this with an appropriate segment of a spherical surface. Where it attaches, there must be a localized thickening for the extra strength to take geometry-induced bending loads locally, and the stress concentrations induced by the attachment fittings and the seals. In the example of a solid motor case, the cylinder is quite thin, except at the ends where the closures go. There it is about 2 or 3 times as thick, depending upon what style attachment you are going to use. The end closure has a thin spherical-segment membrane with a thicker ring at its periphery. This thicker ring stabs into the thicker end of the cylinder. The seal and the attachments (usually pins or some sort of snap ring) go in this joint, where the metal is thicker on both parts.
Just things to think about when laying out designs for cabins that can be pressurized, when adjacent cabins are not. A spaceship really is like an ocean ship in many ways. But there are some things that are quite different, and those will seriously impact how you design it.
GW
Last edited by GW Johnson (2021-12-06 10:16:09)
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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BTW, Merry Christmas, guys! Happy Hannukkah, whatever applies!
I put a funny up on exrocketman that is seasonal, and oddly applicable. Y'all might enjoy it. See "Christmas Decoration", posted 12-7-21.
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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Today's early Zoom meeting is not yet subscribed. It is UTC 14:09 as this post goes up. The offered time for the early Zoom is 19:00 London time.
However, neither a host nor a participant have announced themselves, so I expect that this opportunity will once again pass by unutilized.
The later Zoom is ON schedule ... there is a host and the equipment will be online at (or just before) 1 AM Monday London time.
I am planning a short business meeting, and then will turn over the floor for break out sessions as usual.
The Large Ship seems to be advancing rapidly in the accelerated pace of Zoom Collaboration.
***
Once again, I offer apology for (apparently) causing a disruption of the meeting last week, due to an attempt to set up an audio(radio) broadcast service so I could work on local chores while listening to the discussion of Large Ship design.
What I did not know (and still don't fully understand) is that Zoom decided it didn't like my setting up a third session at the same IP address. Zoom shut down the session, and GW Johnson was never able to reconnect.
I have solved the technical issues that led to the failure, so expect tonight's session to run smoothly.
(th)
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According to time.is/utc, it is 22:23 in London. We'll open the Zoom session in two hours and (about) 30 minutes.
(th)
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According to time.is/utc, it is 45:06 Monday morning in London.
It is highly unlikely any of our European members are going to be joining this week's Zoom session, but you are certainly welcome.
The Chromebook is engaging with Zoom as we speak ...
The session is started.
I'll sign on from another workstation closer to 1 AM UTC.
Looking forward to whatever discussion happens!
Edit ... I notice that Calliban is logged in !!! It is nearly 1 AM in London, on a work day!
Good Grief! << grin >>
(th)
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Sleeping troubles. I will join the Zoom meetings at some point, but not today.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re Zoom ....
If there's a chance you'd like to meet some of the members, the 19:00 UTC time slot would surely work better.
Tonight's session has kbd512 on hand, and we discussed the posts by yourself and Mars_B4_Moon re crawler.
At UTC 1:38 RobertDyck joined !!!
(th)
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Uuuuuuh. kbd512 left at 10:52pm Central Time. We were talking and he just left. I'll wait for a little bit.
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Aaaaaaaaaaaaa! It happened again. He left while I was talking.
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This was another Zoom session which may be of interest to those who appreciate a wide ranging discussion by two people who come to the topic of Mars Settlement with a wealth of knowledge, the ability to describe complex topics in understandable terms, and willingness to use the Internet to add value to their presentations.
The session was recorded and is potentially available for review by a NewMars member. The procedure is to request a link to the video from SpaceNut.
I was able to listen to the first two (nearly three) hours by wearing a headset able to pickup an FM broadcast from the Zoom meeting. I got all the chores done, and found the presentation worth my time. I've spent many hours listening to broadcasts of the Space Show with David Livingston, and the conversation between kbd512 and RobertDyck was comparable in interest value, though definitely (and understandably) less polished.
We have an opportunity to help RobertDyck to prepare for the presentation he is booked to give to the North Houston chapter of the National Space Society.
At present, RobertDyck has the opening presentation at the Mars 2021 Convention as a building block, but that was a short talk with (effectively) only one question. The talk for the NSS chapter needs to be 60 minutes long and chock full of images, tables, references, links for further reading and whatever else will lift the talk to the level of the typical NSS presenter.
The pay off for all this effort is exposure to a ** very ** well educated audience, and potentially to persons with connections to help with development of the concept.
An approach we might consider is using the Mars Society Professional Zoom recordings to create a presentation to the NSS chapter, and then open the floor to questions, which I expect will be insightful and penetrating.
(th)
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NewMars offers two Zoom sessions on Sundays.
The first is set at 19:00 UTC for the convenience of our European members. So far no one has requested a session at that time, but it is there for when needed.
The first step is for someone to ask for the event. The second is to find a host. Finding a host should not be difficult, because the time is earlier in the day for US participants, and we have multiple members qualified as hosts.
The second Zoom is 1 AM UTC Monday in London. The host will set up a session a few minutes before 1 AM UTC, and the session will remain open for as long as participants care to keep it going. Four hours is a routine duration, when technical discussions really get going.
I will hold a brief business meeting at the opening of the session, and will then listen to the Breakout Discussions using a radio headset. Much of discussion in recent times has been about developing the Large Ship, but it ranges over the entire Mars Settlement landscape.
As a reminder ... it is perfectly acceptable for Zoom attendees to come and go, as their time and interests permit. If you pop in for the brief business meeting, it will be fine with me. On the other hand, if you decide to engage with the long haul truckers, then you'll be in for a time of wide ranging thinking.
There is a new wrinkle ... RobertDyck has received a confirmation to provide a 1 hour talk on Large Ship for the March 12, 2022 meeting of the North Houston chapter of the National Space Society. Former NASA employees are in the mix, and there is at least one PhD level contributor. I am interested in using the Zoom sessions to help RobertDyck to prepare for a successful presentation.
Because RobertDyck will be presenting via Zoom, we have the luxury of preparing short segments ahead of time, and playing them on the day of the meeting, with live questions following each segment. I've never seen this done, but (a) we are the Mars Society, and (b) ** they ** are National Space Society. There is nothing we cannot do, if we set our minds to it.
Executive Director James Burk is recording every Zoom session. I am thinking about asking SpaceNut to ask for the assistance of the Mars Society to prepare for the North Houston presentation. What I have in mind is a video producer volunteer, who would help RobertDyck and his support team to prepare segments of about five minutes length on the various aspects of the Large Ship design we have covered over the past year or so, in the NewMars forum.
Reminder: If you have not already attended a Zoom meeting using the Mars Society Professional account, you will not be able to log in. Just post a note here (in this topic) and I will send you the login information via the email you have on file in your Profile page. You will want to save the information so you can log in without an email in the future.
(th)
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It is 23:17 per time.is/utc as this post goes into the database.
Plans to set up the Zoom session at 1 AM UTC are in place and everything appears to be "go" for the session.
If there is someone not already in possession of the log in keys, who would like to take part this evening, please put a post into this topic before the session starts. I will be happy to send the credentials to the email you have on file in your Profile record.
(th)
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As of UtC 45:45, the Zoom session is up and running.
GW Johnson sent a note that he will plan to join, although the amount of time he can spend may be limited.
I will set up a second workstation a few minutes before 1 AM UTC.
The main topic I would like to introduce for this evening is how we (Zoom participants) might help RobertDyck to prepare for a 1 hour long presentation to the North Houston chapter of National Space Society, on March 12th.
(th)
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As of uTC 1:03 the Zoom is open. kbd512 was logged in at the beginning, but his session went away.
Hopefully whatever happened was temporary.
I'm hoping GW Johnson will be able to join briefly.
RobertDyck has been arriving a bit after the hour in recent times.
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This week's Zoom caught me by surprise.... no doubt the festive season was a factor...
We have an opportunity to start work on the March 12th Presentation on Large Ship.
Unlike with any other presentation I've ever been involved in, modern technology allows us to prepare and (hopefully) to perfect the presentation ahead of time, thanks to the weekly Zoom meetings.
We have more than 12 Zoom meetings available.
I'd like to suggest we divide the planned hour into 12 five minute sections, of which 3 minutes would be a YouTube video to be played by the host, and two minutes would be available for attendees to post questions in the chat window.
At the completion of the prepared sessions, the floor would open for replies to the questions that came in.
if no questions come in after a particular segment, we would just go on to the next video
If the speaker (RobertDyck) is so intrigued by a question he wants to reply immediately, we would allow for that possibility.
In order for this to work, we need buy-in by everyone who would participate.
The key player here is RobertDyck.
The next key player is SpaceNut >> Executive Director James Burk.
I'd like for this presentation to reflect favorably on the Mars Society, and would therefore ask for two things:
1) SpaceNut ... we are going to need the links to the saved recordings
2) SpaceNut ... if there is someone in Mars Society who helped to edit the Conference recordings, please ask for their help with this project.
There are a large number of NSS chapters ... I've lost track of the exact number, but there were a significant number back in the L5 days when I was a (very junior) officer, so there must be more now.
If the talk goes well (as I expect) we may be invited to present to other groups.
*** Emphasis *** This is the (original) Large Ship. It is not one of the many spinoffs that will (no doubt) come into existence, starting with the fabric tent design of kbd512.
This is a Queen Mary class vessel, and it will have the mass and consequences that match.
Construction will be a global undertaking.
Canada has the opportunity to take the lead.
(th)
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For those who will be attending tonight's Zoom ... you are welcome to use time.is/utc to keep track of the opening of the session.
Last week we had a member show up precisely one hour late.
Time now (according to time.is/utc) is 20:40:08
The meeting will open a few minutes before 1 AM London time.
(th)
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Per time.is/utc, it is 00:25 in London .... the Zoom session will open shortly for the US/Canada/Mexico members ....
In preparing for tonight's meeting, I have prepared three Google Documents and shared them with:
1) RobertDyck
2) kbd512
3) GW Johnson
Each has the title: Large Ship Segment N of 12
My hope is that the members who gather in the Zoom session will be able to collaborate in preparing script's for RobertDyck's presentation.
To review, I am imagining a presentation of 12 short videos previously stored on YouTube, interspersed with short time intervals for audience members to enter questions into the chat or to vocalize them in the Zoom meeting, followed by a session of Q&A of as much time as the audience (and the host) may desire.
This entire concept is open for discussion/modification/elimination as the Zoom members may decide.
(th)
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