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#1101 2022-01-23 17:21:28

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

I checked my script using online calculators, and the values appear to match.  The following code requires node.js to execute from the command line.  After downloading and installing node.js, execute the script from the command line using the following commands (make sure you run the program in the same directory where you save the script):

command_line_prompt>node
(starts the node.js program)
>.load test_program.js

After node.js parrots back all lines of code, you should see output similar to the following at the end of its execution:

mass m (in kilograms) = 350
radius #2 / r2 / outer radius (in meters) = 5.5
radius #1 / r1 / inner radius (in meters) = 5
Ix-plane moment of inertia (in kilogram-force meter) = 4864 kg*m^2
Iy-plane moment of inertia (in kilogram-force meter) = 4864 kg*m^2
Iz-plane moment of inertia (in kilogram-force meter) = 9669 kg*m^2
Ix-plane Rotational Kinetic Energy (in Joules) = 859 Joules
Iy-plane Rotational Kinetic Energy (in Joules) = 859 Joules
Iz-plane Rotational Kinetic Energy (in Joules) = 1707 Joules
Ix-plane Rotational Kinetic Energy (in foot-pounds force) = 634 ft*lbf
Iy-plane Rotational Kinetic Energy (in foot-pounds force) = 634 ft*lbf
Iz-plane Rotational Kinetic Energy (in foot-pounds force) = 1260 ft*lbf
Ix-plane Rotational Kinetic Energy (in kilogram-force meter) = 88 kg*m^2
Iy-plane Rotational Kinetic Energy (in kilogram-force meter) = 88 kg*m^2
Iz-plane Rotational Kinetic Energy (in kilogram-force meter) = 175 kg*m^2

Script logic to save into the "test_program.js" JavaScript file shown below:

/*
Program Language: JavaScript
Program Execution Tool: node.js
Program Definition: Thick-Wall Cylinder Mass Moment of Inertia (MMOI) and Rotational Kinetic Energy (RE) Calculator
Author: kbd512
Date of Publication: 23 January 2022
Notes: Feel free to use this script as-is or modify it to your liking; this script is only intended to provide ballpark MMOI and RE values
*/

// mass of thick-walled cylinder object, in kilograms
var m = 350;
// outer radius of cylinder wall, in meters
var r2 = 5.5;
// inner radius of cylinder wall, in meters
var r1 = 5;
// height of cylinder, in meters
var h = 1;
// revolutions per minute
var rpm = 5.675;
// formula for calculating the X plane moment of inertia for a thick-walled cylinder when the X-Y plane runs through the middle of the cylinder
var Ix = (1/12) * m * ((3*(Math.pow(r2,2) + Math.pow(r1,2))) + Math.pow(h,2));
// formula for calculating the Y plane moment of inertia for a thick-walled cylinder when the X-Y plane runs through the middle of the cylinder
var Iy = Ix;
// formula for calculating the Z plane moment of inertia for a thick-walled cylinder when the X-Y plane runs through the middle of the cylinder
var Iz = 0.5 * m * (Math.pow(r2,2) + Math.pow(r1,2));
// unit conversion; 1 rpm = 0.10472 rad/s
var rad_s_to_rpm = 0.10472;
// uses revolutions per minute as the input to Omega, versus radians per second
var ω = rpm * rad_s_to_rpm;
// Rotational kinetic energy (RE), expressed in Joules
// I = moment of inertia / mass moment of inertia, expressed in kg*m^2
// ω (Omega) = angular velocity of the object, expressed in radians per second, or revolutions per minute after converting
// RE = 0.5 * I
// X-plane RE calculation; presumes that the X-Y plane bisects the cylinder in the Z plane
var Ix_RE = 0.5 * Ix * Math.pow(ω, 2);
// Y-plane RE calculation; presumes that the X-Y plane bisects the cylinder in the Z plane
var Iy_RE = Ix_RE;
// Z-plane RE calculation; presumes that the Z plane is the axis of rotation
var Iz_RE = 0.5 * Iz * Math.pow(ω, 2);
// unit conversionl 1 Joule = 0.737562 foot-pounds force
var Joule_to_lbf = 0.737562;
// unit conversion; 1 kilogram-force meter = 9.8066499997 Joules
var Joule_to_kgf = 9.8066499997;
// unit conversion; 1 foot-pound force = 0.13825 kilogram-meters force
var lbf_to_kgf = 0.13825;
// output of variable inputs and Iz-plane moment of inertia (cylinder rotating about Z plane running through the "center of the pipe")
console.log('mass m (in kilograms) = ' + m);
console.log('radius #2 / r2 / outer radius (in meters) = ' + r2);
console.log('radius #1 / r1 / inner radius (in meters) = ' + r1);
// Output of moment of inertia values for X / Y / Z planes
console.log('Ix-plane moment of inertia (in kilogram-force meter) = ' + Math.round(Ix) + ' kg*m^2');
console.log('Iy-plane moment of inertia (in kilogram-force meter) = ' + Math.round(Iy) + ' kg*m^2');
console.log('Iz-plane moment of inertia (in kilogram-force meter) = ' + Math.round(Iz) + ' kg*m^2');
// Rotational kinetic energy values for X / Y / Z planes, in Joules
console.log('Ix-plane Rotational Kinetic Energy (in Joules) = ' + Math.round(Ix_RE) + ' Joules');
console.log('Iy-plane Rotational Kinetic Energy (in Joules) = ' + Math.round(Iy_RE) + ' Joules');
console.log('Iz-plane Rotational Kinetic Energy (in Joules) = ' + Math.round(Iz_RE) + ' Joules');
// Rotational kinetic energy values for X / Y / Z planes, in foot-pounds force
console.log('Ix-plane Rotational Kinetic Energy (in foot-pounds force) = ' + Math.ceil(Ix_RE * Joule_to_lbf) + ' ft*lbf');
console.log('Iy-plane Rotational Kinetic Energy (in foot-pounds force) = ' + Math.ceil(Iy_RE * Joule_to_lbf) + ' ft*lbf');
console.log('Iz-plane Rotational Kinetic Energy (in foot-pounds force) = ' + Math.ceil(Iz_RE * Joule_to_lbf) + ' ft*lbf');
// Rotational kinetic energy values for X / Y / Z planes, in kilogram-meters force
console.log('Ix-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil(Ix_RE / Joule_to_kgf) + ' kg*m^2');
console.log('Iy-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil(Iy_RE / Joule_to_kgf) + ' kg*m^2');
console.log('Iz-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil(Iz_RE / Joule_to_kgf) + ' kg*m^2');
// Double check of kilogram-meters force unit conversion
//console.log('Ix-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil((Ix_RE * Joule_to_lbf) * lbf_to_kgf) + ' kg*m^2 #2');
//console.log('Iy-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil((Iy_RE * Joule_to_lbf) * lbf_to_kgf) + ' kg*m^2 #2');
//console.log('Iz-plane Rotational Kinetic Energy (in kilogram-force meter) = ' + Math.ceil((Iz_RE * Joule_to_lbf) * lbf_to_kgf) + ' kg*m^2 #2');

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#1102 2022-01-23 17:40:54

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

Robert,

Program output for provided radius / rpm / height values, presuming a 3m thick cylinder and total mass of 5,000,000kg / 5,000t:

mass of thick-walled cylinder m (in kilograms) = 5000000
radius #2 / r2 / outer radius (in meters) = 40.6992
radius #1 / r1 / inner radius (in meters) = 37.6992
cylinder height (in meters) = 19
revolutions per minute (about the Z plane / axis) = 3
Ix-plane moment of inertia (in kilogram-force meter) = 3997484868 kg*m^2
Iy-plane moment of inertia (in kilogram-force meter) = 3997484868 kg*m^2
Iz-plane moment of inertia (in kilogram-force meter) = 7694136403 kg*m^2
Ix-plane Rotational Kinetic Energy (in Joules) = 197268894 Joules
Iy-plane Rotational Kinetic Energy (in Joules) = 197268894 Joules
Iz-plane Rotational Kinetic Energy (in Joules) = 379692188 Joules
Ix-plane Rotational Kinetic Energy (in foot-pounds force) = 145498040 ft*lbf
Iy-plane Rotational Kinetic Energy (in foot-pounds force) = 145498040 ft*lbf
Iz-plane Rotational Kinetic Energy (in foot-pounds force) = 280046530 ft*lbf
Ix-plane Rotational Kinetic Energy (in kilogram-force meter) = 20115829 kg*m^2
Iy-plane Rotational Kinetic Energy (in kilogram-force meter) = 20115829 kg*m^2
Iz-plane Rotational Kinetic Energy (in kilogram-force meter) = 38717829 kg*m^2

I believe that the Ix / Iy plane RE is the force applied to the spokes of the hubs and center barrel section, so 20,116 metric tons force.

I'm still working out what we need to apply from the following page to compute the rate of precession and the force that must be counteracted to prevent precession:

Real World Physics Problems - Gyroscope Physics

Last edited by kbd512 (2022-01-23 18:05:07)

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#1103 2022-01-23 18:23:16

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

Now that we've calculated the moment of inertia and torque applied, we can use the formulas in the following page:

Precession of a Gyroscope

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#1104 2022-01-23 18:48:48

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

Do you have a mass estimate for standard cabins? How about luxury cabins? Kitchens? Dining rooms?

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#1105 2022-01-23 18:55:10

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

Precessional angular velocity is then:

ωp = (r * M * g) / (I * ω)

(37.6992 * 5,000,000 * 3.724m/s2) / (20115829 * 0.314166666666667) = 111.07434775252813 rad/s (6,364.091339 °/s)

That can't be right.  There must be some kind of unit conversion issue here.

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#1106 2022-01-23 19:03:34

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 25,280

Re: Large scale colonization ship

g is near zero...in space

I=m*r^2

direction of travel f is the one where we would control the wobble as the bike tire rotation shows.

the imbalance is the change in r due to mass shift along the rings width.

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#1107 2022-01-23 19:37:45

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

SpaceNut, you could join us on the Zoom call. Right now.

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#1108 2022-01-23 19:44:25

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 25,280

Re: Large scale colonization ship

I do not have the capability with my equipment...sorry or the quite location to do it with in.

Now back to gravity unfortunately what we are talking about is not gravity at all but Centrifugal Force and Centripetal Force either by means to create one the other or both. The Formula Fc = mv2/r is used for both forces...

Centripetal-force.jpg

Centripetal

http://www.diffen.com/difference/Centri … etal_Force

Cutrope.gif

Both forces are calculated using the same formula:

    F = ma_c = \frac{m v^2}{r}

where ac is the centripetal acceleration, m is the mass of the object, moving at velocity v along a path with radius of curvature r.

3_2.jpg

https://www.artificial-gravity.com/sw/SpinCalc/

http://www.artificial-gravity.com/Space … v3p192.pdf
HABITABILITY FACTORS IN A ROTATING SPACE STATION

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#1109 2022-01-24 11:58:28

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

This announcement may be of interest to RobertDyck ...

For SpaceNut ... this could go into multiple locations ... I chose Large Ship because of the importance of food to the well being of the passengers and crew.

https://www.yahoo.com/lifestyle/nasa-bi … 43520.html

Michael Walsh
Mon, January 24, 2022, 11:31 AM EST
It’s not a question of “will” mankind will ever step foot on Mars. It’s a question of “when” we will. However, before that happens, scientists have to answer a whole lot of other questions first. And once again NASA is turning to the public to help it solve one of the biggest. After looking for assistance developing a lunar loo, the space agency wants your best ideas on how to feed astronauts on longterm missions. And the winner of the Deep Space Food Challenge will get more than big time bragging rights. They will also get a big time prize.


NASA and the Canadian Space Agency have announced Phase 2 of the Deep Space Food Challenge with a video from the food world’s own scientist Alton Brown. The international contest is looking for “novel food production system technologies” for long-duration missions in space. A system that can supply, at minimum, a three-year round-trip that will not have a resupply. NASA and the CSA have also want a system that uses “minimal inputs” while maximizing “safe, nutritious, and palatable food outputs.” Because if we’re going to send people on years-long journeys, we’re going to need a way to provide them with healthy, tasty food. No one wants a real-life Mark Watney poop potato situation. Although, if we’re being fair, Watney did build an extremely efficient system…

The hope is that this challenge will also benefit everyone here on Earth the way past space exploration technologies have. Breakthroughs in space food production could also help remedy food issues everywhere on our planet.

An animation of Alton Brown as an astronaut on Mars carrying a basket of food away from a gorcery store
NASA
NASA will select ten US teams from the initial entrants to move on to the final on-site demonstration, with each team getting $20,000. As many as five from that group will then get $150,000 and an invitation to compete in Phase 3. (If Phase 3 is opened to competition.) US teams don’t need to be finalists to get a bonus reward either. NASA will also recognize five international teams as Phase 2 finalists. And the agency will declare as many as three as winners.

Registration for eligible teams will remain open until February 28, 2022. Multiple submission deadlines will follow in the spring and summer. NASA will name finalists in January 2023 with on-site demonstrations following the next month. And in March 2023, NASA will announce the winners.

Not a lot of time if you’re planning to start from scratch. But when the question of when we’re going to Mars, the clock is already ticking.

The post NASA’s Big Deep Space Food Challenge Comes with a Big Prize appeared first on Nerdist.

(th)

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#1110 2022-01-25 10:34:11

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck ...

I asked Google for the diameter of the Falcon 9 fairing ...

5.2 m
The fairing is jettisoned approximately 3 minutes into flight, and SpaceX continues to recover fairings for reuse on future missions.
...
Payload.
HEIGHT    13.1 m / 43 ft
DIAMETER    5.2 m / 17.1 ft

If your model space craft can be shipped as a model that fits inside the fairing (and only weights 200 kg) then (theoretically) you could have a scale model that is 5 meters in diameter compared to the full scale version of Large Ship.

I have (by now) forgotten the dimensions of Large Ship, but they should be easy to find in the archive of this topic.

The scale for the model might be 1:20 or close to that.

***
I'd like to remind you that the (American) football is a shape that is evolved to spiral great distances without developing deviation along the Z axis.  Your Large Ship might turn out to look like a football, if my intuition is correct.

The opportunity to secure funding from American football interests is "out there" as a possibility.

(th)

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#1111 2022-01-25 10:36:31

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck ...

Speaking of NOT having dimensions of Large ship readily available ...

A folder was recently created for RobertDyck in the NewMars Dropbox.

Please consider storing facts about Large Ship in that location, so they are easy to find by anyone on the internet with a simple direct link.

The hodge podge of facts currently scattered over 2 years of NewMars posts are unhelpful.

(th)

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#1112 2022-01-25 11:47:53

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

tahanson43206,

I checked the Deep Space Food Challenge. The article on Nerdist was published the same day you posted, but Phase 1 is already over with winners announced. The US website is hosted by a partner with NASA, and does accept applications for Phase 2, even if you didn't participate in Phase 1. However, the Canadian website says applications are closed. I sent an email to the Canadian Space Agency anyway.

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#1113 2022-01-25 11:57:05

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

I have described this project in detail. kbd512 apparently didn't read the part about two decks of the ring and deck height. However, I did say one reason for trying to work out salad bar details was to calculate greenhouse size. So detailed dimension are being worked out.

Mass calculations are not available because details configuration of the kitchens have not been worked out, detailed mass of cabins either. I tried to estimate cabin mass based on composite cabins built for cruise ships, but unfortunately it's not applicable. Those cruise ship cabins are larger than on the space ship, and cruise ship cabins are complete with walls/floor/ceiling etc. The ship has a pair of steel I-beams sticking out from the structure of the corridor, the cabin is slid onto the I-beams as a complete unit. Our cabins are within a spacecraft hull. I estimated hull mass, but that means cabin mass does not include ceiling, floor, outside wall, and half the cabins use a pressure bulkhead as one side wall. That means only the corridor wall and other side wall are composite. Cabins not adjacent to a bulkhead have corridor wall and two side walls. Outside cabins facing aft will have a composite wall for the outside wall, because the water bladders for the "water wall" will be between the hull and that interior wall. All this requires a detailed design for a mass estimate.

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#1114 2022-01-25 13:02:16

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck re #1113

First, best wishes for a favorable response from the deep space nutrition competition!

Second, thank for your response regarding specifications of dimensions and other known features of Large Ship.

You have set some features of Large Ship in stone.  Please publish those in the file folder provided for you in the NewMars Dropbox account.  There should be no need for anyone to have to search your thousands of posts to find it.

The radius of the swing arm is some number of meters.  I know what it was at one time but have forgotten.

I want to be able to go to one immutable permanent repository to find it.

I ** do ** remember that you have chosen 20 seconds as your cycle time.

That is very close to the time chosen by the space station design that SpaceNut showed us.

However, those folks are going for a higher gravity quotient.  Your's is set at Mars equivalent, as I recall.

***
I have tried to show how the design of sea going aircraft is available to you from what I hope are public records. You should be able to recover details of cabin design and furniture from those successful flying machines.  You should be able to use ** ALL ** that hard won experience.

There should be NO need for you to invent anything!

Just use what (hopefully) is public data

(th)

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#1115 2022-01-26 19:36:27

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

Robert,

Apologies in advance for the rambling on.

I did try to go back through this thread and find that information before asking you about it again, but after reading through dozens of different posts I gave up on that.  Maybe you could post a "Large Ship Sticky Note" with the current dimensions / masses / specific configuration details.  Knowing exact dimensions / materials used ( 304 stainless / polyethylene / Al2219 / etc) / masses (down to geometry) / rotational rate is critical for computing the torque that must be counteracted.  We have the correct formula to use from GW to calculate torque (Precession Rate * Mass Moment Of Inertia * Omega = torque), but we still need a reasonably good approximation of the masses, mass distribution and the precise dimensions for MMOI calculations.  For example, that water tank is located on one side of the habitation ring (facing towards the bow of the ship).  That affects the MMOI formula we should use, which was for a cylinder where the X-Y plane bisects the length of the cylinder.  If the mass of water is on one side, then we should use the "1/12" vs "1/2" version of the formula for when the X-Y plane is on one end of the cylinder (and that is not exactly correct for our purposes because the mass distribution is different).

Knowing the precise dimensions of the water tank and what its expected fill percentage will be is important.  I presume water will be going in and out of the tank as it's consumed, recycled, and ultimately pumped back in, which means the tank either needs to be larger than the minimum size required or a lot more working / circulation water is required.  For daily use to supply 1,000 people, we're talking about tens of thousands of gallons of water, even on a Navy ship with "push-to-talk" shower heads.  We also need hot water tanks for the scullery and showers.  Cold water is stored in the flash evap tank (the "radiation shielding" tank in this ship's design), and then there are a number of large hot water tanks (containing additional thousands of gallons) throughout the ship.  I suppose point-of-use electric heaters could be substituted, though.  Is the tank straight stainless with no liner or will it have a HDPE liner the way large water tanks are either coated or lined here on Earth?  A lower mass option to a plastic liner is all-welded steel construction with a baked-on CeraKote liner.  They've started using CeraKote on steel water tanks instead of plastic, because it's cheaper / more durable if the tank flexes, as this one will / weighs less / can be easily replaced by bead blasting the existing coating off and then baking a new coating on.  Either way, the salts added to adjust pH will attack stainless, even though it will corrode more slowly than plain carbon steel.  I learned that from talking to the engineers who maintained our ships.  I will presume straight stainless for starters since that's the lowest possible mass, but that's not realistic since the tank won't last without a ceramic or plastic liner.  We need a rough idea of the volume of the atmosphere and water vapor content, because even for my much smaller ship's pressurized volume, it's thousands of kilograms.  We'll put every mass together as discrete "mass components" and then use simple summation to arrive at the MMOI value.

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#1116 2022-02-01 10:55:33

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck ...

I've asked the members of the North Houston NSS chapter to think of questions ahead of your talk.  At last a question showed up ...

Question about the "large ship"...Why is the ship so large?  We can only lift components that are so large with Falcon Starship.  It seems more efficient to lift hundreds of smaller ships than to have one ship with many single points of failure due to a large number of welds.

I'll keep asking for more, but the contact has a lot going on beside this specific topic. 

(th)

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#1117 2022-02-01 12:48:02

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,505

Re: Large scale colonization ship

Aerospace welds are made in such a way that the fastener ("the weld") holding two or more components together is as strong or stronger than the base metal.  When done properly, a weld is not weaker than the base metal.  Welding, riveting, threaded / stretched bolts or studs, and adhesives or other chemical bonding techniques are all approved aerospace fabrication techniques for constructing larger assemblies from much smaller parts that are easier to work with / form parts from.  Thrust structures for rocket engines are commonly fabricated using a combination of forgings, threaded fasteners, and welded tubular steel.  If the welds were a weak point, then very complex forgings or billet parts would be required, but that's not how we do it, because welding works so well.  The propellant tanks for Starship are all-welded stainless steel, with some bolt and/or stud & nut fasteners used for major sub-assemblies.

The reason for using much larger ships is directly related to the critical systems redundancy of larger ships, the impracticality of launching thousands upon thousands of smaller ships to Mars and then sending them all the way back to Earth from the surface of Mars (but having to wait 26 months to do that), as well as the issue with the comparatively flimsy construction of these much smaller ships.  Traffic control in LEO is already a serious problem.  Using a much smaller number of larger and better protected ships ensures that the shooting gallery problem is not greatly exacerbated.

Instead of lifting much smaller ships into orbit again and again, you push the components of a much larger ship to LEO only 1 time, and then that ship makes round trips between LEO (Low Earth Orbit) and LMO (Low Mars Orbit) over the course of its operational service life.  Thereafter, instead of continually pushing more tin into orbit, from the surface of Earth and the surface of Mars, you instead load ships with consumables and propellants.  The ship goes to Mars, dumps its load of people and cargo, then returns to Earth.  It does not have to survive multiple reentry events, nor does it have to generate that 14km/s+ of Delta-V to go from a dead stop sitting on the surface of Earth or Mars to orbital velocity.  If you think that pushing the components for a larger ship into orbit one time is bad, then pushing the same mass repeatedly into orbit from a dead stop, both ways, is much worse.

The large ship concept provides solar radiation protection, substantial micro-meteoroid / debris protection, abundant power, redundant life support, and generous volumetric accommodations for the 6+ month transit.  It's akin to an ocean cruise liner, rather than a spam can.  Since it does not reenter the atmosphere, it is not subjected to the extreme heating and vibration of vehicles making hyper-velocity atmospheric reentries.  Basically, it's a true interplanetary transport, rather than a rocket upper stage / lander that does a poor job at all three because it can only ever be optimized to function as a rocket upper stage.  The design requirements for the upper stage of a rocket are grossly incompatible with the design requirements of a vessel intended to be an excellent in-space transport that operates solely in deep space.  The upper stage of every rocket has been designed to be as thin and light as possible, carrying the maximum amount of propellant and the minimum number of engines to boost that upper stage into orbit from the surface of a planetary body, with or without a booster stage.  It simply cannot be optimal for radiation shielding or life support redundancy or crew comfort, because that would make it unsuitable as a rocket upper stage- and that is the only way that it well ever perform any of those other functions, however poorly.

If you don't have a fully reusable heavy lift launch vehicle, then you don't have a colonization program, period.  However, the best use for that fully reusable rocket is acting as a ferry to build and supply much larger ships that stay in orbit, in conjunction with a handful of Low-Orbit-to-Surface ferry rockets that stay on Mars and are purpose-built for stable rough field landings.  Going from 4km/s to 0 on Mars is a different proposition than then 8km/s to 0 on Earth.  The heat shielding requirements for both vehicles are drastically different.  We don't need to build a single vehicle that does absolutely everything, because it can only ever do one thing well.

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#1118 2022-02-01 13:23:48

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

kbd512: very well said. Whu' he said.

SpaceX Starship is welded. It's made of sheet metal with a vertical seam to hold ends together into a ring. Then rings are welded together to form the tank. Using smaller Starships doesn't get away from welding, they're welded anyway.

Besides, a larger ship benefits from cube-square. Volume increases as the cube, but hull surface as the square. So less surface area to protect against micrometeoroids and orbital debris.

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#1119 2022-02-01 13:47:27

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For kbd512 and RobertDyck ...

Thanks both for helping RobertDyck to prepare for March 12th!

The content provided could be set up as a reference for the audience, by packaging it as a pdf and storing it in the NewMars Dropbox.

All we would need at presentation time is a link, if this question comes up (which I expect it would).

I'll keep asking my contact to forward any similar questions!

(th)

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#1120 2022-02-05 14:31:12

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck ...

From today's Zoom meeting with NSS North Houston ...

Meanwhile, we have a request from NSS North Houston to RobertDyck ... they would like to advertise your talk ahead of your presentation on March 12th.  Please provide them with the text you want them to show on their web site.

You are welcome to send it to NewMarsMember if that is convenient.  I'll forward it immediately.

You can look at their web site to see how they are advertising next week's talk: northhoustonspace.org

(th)

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#1121 2022-02-05 17:45:56

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

That website lists a speaker for February. It has a picture of the speaker, and a brief bio, it doesn't say what she will speak about. How about this:

Robert Dyck

Rob has been a member of the Mars Society since 1999, just one year after its founding. He founded the local chapter in Winnipeg and continues to be an active member. Rob gained an interest in space as a young child during the Apollo race to the Moon. This talk will be a Large Scale Colonization Ship, capable of carrying roughly 1,000 people to Mars. Advantages of a single large ship over a cluster of smaller ones, features required to carry that many settlers safely and in relative comfort. Many details of the ship will be covered. This has been discussed for over 2 years on the Mars Society forum, and a half-hour presentation was given at the Mars Society virtual convention last fall. This presentation will be a full hour, covering more detail.

::Edit:: If you want an image of the ship, you can take it from post #882

Last edited by RobertDyck (2022-02-06 11:23:07)

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#1122 2022-02-05 18:16:00

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck re #1121

Looks good to me! Thanks!  I'll forward your suggested text tomorrow.

In addition to that, the NSS web site updater can pull from the many posts in your topic.  I'll suggest that as a possible source for images.

GW Johnson has been breaking trail for you by providing the positive aspects of your work when opportunity presents itself.  You (and the forum) have had two years to mentally prepare for the size ship you're thinking about.  I observe that a person encountering these ideas cold may need some time to adjust. Your suggested ad/poster text seems to me to encourage prospective audience to expand their thinking.

(th)

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#1123 2022-02-06 11:25:08

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

I filled in a Google Docs document. Rather than separate documents, I put the whole thing in document #1. With Microsoft Word, I added an automatic table of contents with hyperlink to page, but that didn't come through with Google Docs.

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#1124 2022-02-06 11:32:31

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 9,905

Re: Large scale colonization ship

For RobertDyck re presentation at ISDC...

https://isdc2022.nss.org/call-for-abstracts-form-page/

Please consider filling out an application.  We (appear to) still have time to apply for a slot for your Large Ship talk.

The North Houston chapter will be in a position to support your bid, after March 12th.  They are favorably inclined at this point, based upon the recommendations of GW Johnson and tahanson43206, so if your talk goes well (which seems highly likely) they may (I'm hoping!) be willing to put in a good word at ISDC.

We need your bid on record as soon as possible so the conference committee can slot it appropriately.

***
Re Google Docs ... thanks for working on that!  I'll check it out after looking at GW's draft for a new paper.

(th)

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#1125 2022-02-06 12:15:08

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,241
Website

Re: Large scale colonization ship

Are these presentations virtual, or in-person. I ask because Canadian regulations to board an aircraft, or return to the country.

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