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#51 2020-08-15 13:22:56

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

RobertDyck wrote:

This topic started with the premise: Elon Musk said the next ship after Starship would be twice diameter and twice height, so 8 times volume. This ship was designed to have the same volume, but go from Earth orbit to Mars orbit and back, with artificial gravity. Ok, the hub would provide more volume than Starship 2, but still...

Radius from centre of rotation to surface of floor: 37.76 metres. 3 RPM. 38% gravity = Mars surface equivalent. One deck. Circumference: 237.25 metres. Ring width 19 metres. This allows 2 isles for cabins, corridors 1.5 metres wide, outside cabins have a window, inside cabins do not. Standard cabin size 4x2.4 metres. Cabins are also 2.8 metres (8 feet) high. These figures are from the initial post.

Cabins configures with short end along side wall, so outside cabins have 2.4 metres of exterior hull. Width of the ring is 4 metres for first cabin, plus 1.5 metres for corridor, plus 4 metres for inside cabin, then 4 metres for inside cabin facing the other corridor, then 1.5 metres for that other corridor, then 4 metres for the last outside cabin. Total 19 metre width. (Yes, Canada uses the British spelling for metre. But it's still pronounced "meter".)

Hohmann transfer orbit is minimum energy; it takes 8.5 months. "Express" trajectory requires 10% more propellant; it takes 6 months one-way from Earth to Mars. This is actually the "Free Return" trajectory. That means if something goes wrong, gravity of Mars will alter spacecraft flight path to return to Earth. It'll take more than 6 months to get back, but you'll get back when Earth is at that location. Getting back to Earth's orbit about the Sun when Earth is somewhere else in it's orbit is not useful.

Lifeboats: I hadn't considered that. Had instead focused on pressurized sections, redundant life support, and using the ship itself. You could add inflatable fabric rescue spheres. NASA developed a personal rescue enclosure (ball), but the ship could make them larger, able to accommodate several people.

200px-First_Six_Women_Astronauts_with_Rescue_Ball_-_GPN-2002-000207.jpg


Self sufficiency: My design would use parabolic mirrors on the sun-facing side of the ring to reflect sunlight into light pipes. These light pipes would direct sunlight to life support for each cabin. Each cabin would have it's own life support. Regenerable sorbent to remove CO2, dehumidifier to remove cabin humidity, urine processor for toilet, water processor to produce portable water. Instead of water electrolysis, each cabin would have a bag of in-vitro chloroplasts to convert CO2 and water into O2 and carbohydrate. The carbohydrate would be filtered, concentrated, then sent along a tube to ship's central life support. This will provide starch, but other food will be stored. Roof of the ring will have hydroponic greenhouses to grow fresh greens and tomatoes for salad. Other food will be stored. Dehydrated food to reduce mass, re-hydrated with recycled water.

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#52 2020-08-15 13:24:15

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

tahanson43206 wrote:

Today, while awaiting possible advice from RobertDyck, I have started an attempt to build up a model of Big Wheel Gyroscopic Spaceship using Fusion 360, with which I am still very much a novice.

Using the 56 meter radius suggested by GW Johnson for a rotating habitat that yields 1 g at 4 rpm, combined with the length of a SpaceX second stage of the Starship design as 50 meters, I have begun with a sketch.  In hopes that there might be someone who will come along later and perhaps want to try something like this, here is the first output of a "sketch" session in a clean workspace.

WU3Z3bD.png

The circle is defined with a diameter of 112, which is 112 mm in Fusion 360 design default grid.  That would be a 1:100 scale model.

Edit#1: Here is a look at what a circle of Starship second stages might look like, if set inside the perimeter of a 112 diameter circle:

Starship: 9 meter diameter (per Google)

Radius of habitat: 56 meters  Diameter is 112 meters.

39 copies of Starship could be placed inside the perimeter of a habitat, if they were set at the circumference.

112 * Pi / 9 >> 39.095+

However, the centers of the Starships would be inside the perimeter by 4.5 meters.

That would be a circle with a diameter of 103 meters

The circumference of a circle with diameter of 103 meters is 323.58+ meters

That number divided by 9 is 35.95+

Since it is unreasonable to try to squeeze the starships together like that, I think a reasonable estimate is 34.

(th))

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#53 2020-08-16 06:25:46

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

In another topic ("Large Ship") RobertDyck has been reminding readers of a potential problem with a rotating mass habitat.

http://newmars.com/forums/viewtopic.php … 98#p171198

The problem of instability caused by movement inside a rotating habitat while it is moving from Earth to Mars (and back) is significant and it must be accounted for with countermeasures.

A gyroscope used for navigating in a vehicle on Earth or in space, must be manufactured to the highest level of precision of which humans are capable.

A "gyroscope" created as a habitat for human passengers and crew is going to be undergoing constant varying movements of mass inside the structure.

There is need for computer analysis of the nature of the problem, and specifically what countermeasures will be needed to insure the rotor remains balanced to the extent necessary.

The Earth is an example of a large rotating mass that is (relatively) stable despite the constant random movement of mass in all layers, but (I understand) even the Earth is subject to the influence of moving masses.

Here are a couple of citations provided by Google:

However, the Earth is not spherical, and the mass within it is both unevenly distributed and prone to moving around. ... What's more, because the rotation axis is different to the figure axis around which its mass is balanced, the Earth wobbles as it spins.Dec 5, 2016

The Earth does not just spin: it also shakes and wobbles

and ...

Study solves two mysteries about wobbling Earth – Climate ...climate.nasa.gov › news › study-solves-two-mysteries-a...
Apr 7, 2016 - Earth does not always spin on an axis running through its poles. ... That direction has changed drastically due to changes in water mass on Earth. ... how the movement of water around the world contributes to Earth's rotational ...

It seems to me reasonable to conclude that a large rotating habitat, filled with people going about their daily lives, will inevitably wobble.

A space transportation system designed to include such a rotating habitat must be designed to manage the wobble, which will place a strain on bearings that site between the shaft supporting the habitat, and the external, non-rotating portion of the ship.

It seems possible that fast acting electromechanical devices might be able to counter disturbances caused by movements of people or masses inside the habitat, but energy will be required to monitor the condition of the habitat and to direct countermeasures as necessary.

It also seems possible that movements of people might be coordinated so some degree to avoid excessive demands on the momentum compensating systems.

Call for Assistance...

To the best of my knowledge, the membership of this forum does not include a person with the computational resources that would seem necessary to model a large rotating habitat in space.  If a reader of the forum is interested in helping, and has the available resources, please consider registering and posting a message or two.

Reminder of contra-rotating habitat disks ... in recent posts, kbd512 has included the idea of using contra-rotating habitat disks to counter some of the challenges that are associated with design of large rotating habitats that will operate in space.

However, excessive wobble within each of the two habitats will lead to excessive wear on roller bearings that transfer forces between the two habitats via their shared shaft.  Thus, I would imagine that momentum management solutions will be required even in a contra-rotating design.

Edit#1: "Low Bridge", "All About", "Fasten your seat belts" .... these phrases all illustrate human adaptation to transportation over many centuries.

In thinking about the needs of a rotating habitat for stability, it seems reasonable to suppose that since humans are going to account for a significant part of the uncontrolled movement of mass inside a habitat, they can (and most assuredly ** will **) be enlisted to help to dampen wobble by preventing it in the first place.

I can imagine that small movements (such as working in the kitchen to prepare a meal) might not have sufficient magnitude to cause a significant effect in a large system, but a birthday celebration with twenty people might well require advance planning with the Momentum Manager, who would be the Air Force equivalent of a Load Master.  That individual would be a member of the Enlisted Crew, and at the top of the ratings within that group.

The Star Trek vision of people wandering at will throughout the habitat would be somewhat constrained in a future which includes rotating habitats smaller than one of Dr. O'Neill's cylinders.

Edit#2: In calling for assistance with analysis of this problem, I am hoping more than one University level team will find the problem intriguing enough to consider asking for the opportunity to do the needed research and publish a paper or two or three.

(th)

Last edited by tahanson43206 (2020-08-16 08:07:18)

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#54 2020-08-16 08:57:34

SpaceNut
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Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

Well when tires are freshly mounted they are balanced to reduce wobble so counter weight balancing of large mass changes would be part design. Since we are needing water shields these could be thin tanks which can move along a rail with detaunt gear teeth and latches to hold in place.

The equations for rotation are derived from motor design which accounts for RPM and torque values.
Torque accounts for mass movement at RPM..

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#55 2020-08-16 10:03:41

tahanson43206
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Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

For SpaceNut re #54

Thanks for thinking about the problem of dynamic balance of a rotating habitat, filled with people who move around randomly, and who call for movement of mass (such as water) from one location in the habitat to another.

The example of a vehicle tire is excellent for illustration of the problem.  The difference (as I see it) is that the "tire" is not as constant in distribution of mass as a road tire would be.  In road service, my observation is that wear on a tire is normally uniform, so that re-seating of lead weights is not necessary at normal vehicle maintenance, but severe travel can necessitate rebalancing of tires.

Your idea of water tanks helping with mass distribution makes a lot of sense to me, but I'd like to suggest you might take a look at pumping the fluid from  one tank to another as an alternative to the mechanical system you proposed.

The dynamic nature of mass location within a rotating habitat implies (to me at least) the equations you described would be in nearly constant use by a computer driven momentum management system.

(th)

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#56 2020-08-16 11:07:19

tahanson43206
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Re: Big Wheel Gyroscope Space Transport

For those who might be interested in following the trail later on, I am using Fusion 360 if free trial mode.  However, it is necessary to pay for add-ins (in some cases).   A Spur Gear Creator Add-in is available for $1.99 (US), so I decided to take a chance on it.  It is mentioned as an option in Lydia Cline's book, so I'm hoping I can figure out how to use it.

Spur Gear Creator
Graham Chow
The app Spur Gear Creator is especially useful for creating wooden or plastic gears.

DescriptionGeneral Usage InstructionsScreenshotsInstallation/UninstallationContactVersion History
Description
The feature of this gear creator are:

You can design a gear that uses a single largest bit to machine.

It can create a pocket so you can easily machine the other side of the gear.

It uses the undercut to define the fillet. You can also specify an ellipse for the fillet to give an unusual looking gear.

General Usage Instructions
The usage of this add in is explained in this video: https://youtu.be/zkPvn0vhc00

Screenshots

The first application I have in mind is creating a template for position of 34 Starship Second Stage forms around the perimeter of a 56 meter radius habitat.  However, beyond that, I can imagine there might be other applications for the tool.

The first that comes to mind is the cog rail way that (I am imagining) would be designed to permit the Propulsion Section to make it's way around the Yoke component of the Big Wheel design, as described in earlier posts in this topic.

Edit #1: I added an Add-In from the Autodesk App Store.  There is (apparently) a free version, but the price of this one is $1.99 (US), so I decided to give it a try:

wg0Bdq1.png

This is the first output of the Add-in, using the default values for a Spur Gear, except for the number of teeth.

The default is 24 teeth. This model is for 34 teeth, which is the number of Starships that would fit inside a perimeter with radius of 56 meters.

This particular model is not sized correctly for use as a template with the planned 56 Meter radius habitat, so I'll have to learn more about using the Add-in to arrive at a correct size.  My first objective was to simply see if the Add-in would work at all, and it appears to work.

(th)

Last edited by tahanson43206 (2020-08-19 12:43:37)

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#57 2020-08-16 16:42:52

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

Sure partially filled tanks of water with air to maintain water bladders internal to the tanks to keep the water stationary to aid in the balancing act of motion. Reserve water would be maintained in the center of spin why waste water and other is kept more external in fixed spaced tanks.

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#58 2020-08-16 17:10:05

tahanson43206
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Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

For SpaceNut re #57

This topic is intended to be a collaborative undertaking.

RobertDyck, kbd512 and GW Johnson are already (somewhat involuntary) participants.

Your interest in using water (and other fluids) to help to maintain mass balance within a rotating habitat suggests you might be interested in developing your ideas further.  While engineering fluid systems may not be your main interest, if you decide to stretch a bit, this would be a useful discipline to pursue.

The water movement subsystem needs to be coupled tightly to a set of computers with sensors able to detect changes of momentum within milliseconds as they occur, so that water can be routed to where it is needed rapidly. 

Earlier you suggested moving masses around mechanically, and I definitely agree this tool should be in the toolkit for the automated momentum balance subsystem.  Extending the thought a bit further ... The least expensive countermeasure should be chosen by the momentum balance subsystem at any instant.  It is possible that a mechanical system might respond instantly, but then water might be moved to relieve the mechanical system and allow it to return to neutral position, ready to respond to the next excursion.

Expending precious mass in an external thrust should most definitely be a last ditch emergency remedy.  Hopefully earlier remedies will be sufficient to handle the vast majority of excursions from perfect balance.

(th)

Last edited by tahanson43206 (2020-08-16 17:10:52)

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#59 2020-08-16 18:45:01

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

The dual purpose with using water is for radiation shielding not to mention for other uses.
Plus we can go slower and further as the crew is protected for any duration mission.

https://www.nasa.gov/vision/space/trave … lding.html

What thickness/depth of water would be required to provide radiation shielding in Earth orbit?

Water as a gamma radiation shielding

Advanced depth-dose curves for fast space radiation dose calculation in a spacecraft with complex geometry

Shielding of Beta Radiation – Electrons

Shielding effectiveness: A weighted figure of merit for space radiation shielding

https://three.jsc.nasa.gov/articles/Shielding81109.pdf

https://www.epa.gov/radtown/cosmic-radiation

https://sciencedemonstrations.fas.harva … -shielding

I am assuming the earth taxi is connect to the center hub tube for entry into the gyro space transport with the lander ship if require on the other as cargo if we do not need a different ship than the taxi.

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#60 2020-08-16 20:35:06

tahanson43206
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Re: Big Wheel Gyroscope Space Transport

For SpaceNut re #59

Thank you for your continued interest in and support of this topic!

Then, thank you for the numerous links to study to help with design of the radiation shielding.

Radiation shielding is needed for radiation arriving from directions other than the Sun.

As a reminder, RobertDyck suggested orienting the edge of the habitat so it is lined up with the Sun.  In other words, the axis of rotation of the habitat would be perpendicular to the line running between the Sun and the center of the habitat. 

With this advice in mind, I added a radiation shield to the Big Wheel design.  This enhancement can be seen in Post #42.

http://newmars.com/forums/viewtopic.php … 83#p171183

The image shown there is of the basic structure enhanced by a radiation shield that is part of the Propulsion unit.

That shield would be filled with material that is chosen for its effectiveness in trapping Solar Flare ions.  Water could well be a part of the filling, but I understand that certain hydrocarbon structures (plastics) are even better at dealing with radiation than water.

Hopefully the links you provided will include guidance for selection of the filling for the radiation shield.

***
Yes, thanks for noting the docking ports envisoned at either end of the Habitat Axle.  The "Captain's Gig" would be used in flight to permit crew access to the propulsion unit if necessary.  However, at major destinations, such as Phobos at Mars or LEO at Earth, those ports would allow for transfer of people and materials into and out of the habitat.

However, for clarification, I am expecting the propulsion unit will be where the materials shipped with the vehicle will be stored if they are not needed in the habitat. 

My concept for developing a plan for the vehicle is to work from the Habitat out.  The Habitat itself is defined as having a radius of 56 meters, and a thickness of 50 meters. 

My immediate next step is to lay out an array of Starship cylinders around the inside perimeter of the habitat.

(th)

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#61 2020-08-17 07:55:11

tahanson43206
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Re: Big Wheel Gyroscope Space Transport

As a follow up to #60, it came to me overnight that the "traditional" aircraft belly shipping container would be a good solution for the current project.

Passengers could load half moon shaped shipping containers with their supplies on Earth, and the shipping company would deliver the entire package to Mars.

Because the diameter of a Starship is 9 meters, and the Starship is under consideration as a structural element in the Big Wheel design, the half moon shipping containers would need to be designed and manufactured for the 4.5 meter radius of the transport.

Because height is needed for design of such containers, I'll arbitrarily start with 2.25 meters at this early point.  It may well turn out that greater height is both appropriate and possible.  2.25 meters is the height computed by planetcalc.com for a chord with an angle of 120 degrees.

The configuration of such shipping containers must include shipping from Earth and landing on Mars.  In those situations, I would expect the containers to be arranged vertically if they are lifted by vehicles smaller than 9 meters radius.

Thickness is another characteristic that needs to be defined, so I'll start with an arbitrary 1 meter.  An online calculator at planetcalc.com gives an area of 12.44 square meters for the 120 degree chord, or 12.44 cubic meters for the shipping container, less the material used for construction.

A passenger needs to plan for a two year journey, so 12.44 cubic meters may be just a starting volume.

Here is a Wikipedia image showing shipping containers designed for belly service in large aircraft.  I note the separation of the space into two sections, and the use of a simple angle cut to fit an otherwise rectangular solid into the available chord shaped space.

images?q=tbn%3AANd9GcTIlo3LMkDTGLUIbAWJpsZFjQJb4Lsx-aky-A&usqp=CAU

This example would inform the idea for the Big Wheel application.  The volume per container would be less and some volume would not be available, but the convenience for loading and transportation of the smaller containers would argue in their favor.

It's even possible that existing products in this category would serve admirably for the purpose.

***
Design of the cylindrical compartments to be installed in the perimeter of the Big Wheel would include dealing with the challenges of loading containers and unloading them at Mars.  The system design needs to include planning for opening the ends of the cylinders to admit containers, but at the same time, insuring air tight capability when the vehicle is operating in lifeboat mode.   Lifeboat drills would be as necessary in a space transport system as they are in ocean transport.

Actually, I don't know if lifeboat drills are standard practice in modern passenger ships. 

(th)

Last edited by tahanson43206 (2020-08-17 08:25:04)

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#63 2020-08-18 07:32:43

tahanson43206
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Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

For SpaceNut re #62

Thank you for more links to study in preparation for decisions about the nature of and placement of radiation protection materials in the Big Wheel design.

***

This post will introduce a new variation of the Big Wheel design .... a Tri-Cornered-Hat design.

The full sized Big Wheel habitat is imagined to contain a significant number of Starship bodies.  The full complement is not yet foreseeable (except to a mathematician), but the outermost ring of bodies numbers 34 in the current design, so there will be fewer in the inside rings, where simulated gravity will be less.

However, a minimal version of the Big Wheel design could be made with just three bodies.  If the design is limited to two bodies, then we would simply have the familiar Dumbbell shape, and that has already been examined in detail.

On the other hand, the Tri-Cornered-Hat design would possess the features that characterize the full Big Wheel design.  The rotating habitat section would operate as a gyroscope wheel, and the Yoke and Propulsion unit components would be almost identical in structure although much less massive due to the much smaller load to be moved in space.

What is more ... the Tri-Cornered-Hat design is potentially attractive to wealthy individuals who might be interested in making a trip out to Mars and back in some comfort and safety, without having to wait for a full sized Big Wheel to come into being.

shopping?q=tbn:ANd9GcRHWLvvYLLzfWfZse7CV4-3lUMtXVDE0-mxf7VSiV42DL4elYCOofgi_6DWF058mQA_V6b-bwZH&usqp=CAc

Edit#1: Introduction of the Tri-Cornered-Hat minimal Big Wheel design reveals a flaw in the full sized configuration.

The natural grown of the Tri-Cornered-Hat would be to increase from three to six, for a Hexagon Big Wheel.

The progression can be anticipated as the sequence of threes: 3 6 9 12 15 18 21 24 27 30 33 ..... the current design features 34 bodies, which would fit comfortably inside a perimeter with a radius of 56 meters.

The next desirable combination of Starship bodies is 36. 

Well, 56 meters is not set in stone.  It is a figure for providing 1 g at 4 RPM.  If the radius is increased slightly, to accommodate 36 Starship bodies, then the RPM can be reduced slightly.

I'll investigate to see what radius would provide a framework capable of holding 36 of the 9 meter diameter cylinders.   It should be noted that the cylindrical compartments would NOT be welded together.  Instead, they would be separated by at least a meter to facilitate ease of movement into and out of the Big Wheel structure.  What I'm thinking about here is the option of allowing Starships to assemble before a flight, and then to secure themselves inside the habitat structure before a flight begins. 

Edit#2: In honor of the Tri-Colored-Hat theme, here are musical selections that reflect the theme:

Manuel De Falla: Suite No. 2 from 'The Three-Cornered Hat' [12:59 minutes]

https://www.youtube.com/watch?v=lkuxnXB7Pho

The Royal Stockholm rehearsal below contains some of the familiar refrains: 3:04 minutes

de Falla The Three-Cornered Hat / Royal Stockholm Philharmonic Orchestra / Xian Zhang

https://www.youtube.com/watch?v=yk718TVDUvc

It would be natural for a company that builds one of these to pay for the rights to play portions of De Falla's work in their advertising.

Even though the original work is long out of copyright, the work of modern orchestra's would be covered.

Edit#3: Given a goal of 36 Starship bodies at the perimeter of the Habitat, and assuming 1 meter between each 9 meter cylinder, then a calculator reveals that a diameter of 114.591655818 would provide the space needed.

The diameter that flows from the 56 meter radius suggested by GW Johnson for 1 g at 4 RPM is 112 meters.

Increasing the radius to 57 meters would provide room for 36 Starship bodies, with slightly less than one meter between them.

I'll make that adjustment to the model in development in Fusion 360.

A family of transports can be developed from the minimal 3 node model to a full scale 36 node version, without changing the Yoke or Propulsion units at all, except for adding strength and capability as the load mass increases.

(th)

Last edited by tahanson43206 (2020-08-18 09:32:42)

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#64 2020-08-19 08:14:49

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

This is a follow up to #63

In adapting the design of Big Wheel to accommodate 36 Starships laid out side by side in the interior wall of the Habitat, I had to increase the radius of the structure to 57 meters from the initial setting of 56 meters, as suggested by GW Johnson for 1 g at 4 RPM.

In working on the design up to this point, I had not paid attention to Mr. Musk's idea of sending 100 passengers in a Starship.  Were this number of passengers to be booked for each of the 36 Starships, the passenger and crew manifest would total 3,600, and that is with NO Starships inboard of the perimeter.

In an earlier post, it was noted that for stability, Starships should be assigned to ports in sets of 3: 3 6 9 12 15 18 21 24 27 30 33 and 36.

However, balance could also be achieved with sets divisible by 2, including 2: 2 4  8 16 32 (powers of 2)

Adding Starships to an inner perimeter would increase headcount and complexity of achieving mass balance.

An advantage would be providing lesser gravity for those who might prefer to adapt ahead of arrival at Mars.

Edit#1: A preliminary investigation of how to distribute mass with varying numbers of Starships reveals a problem I had not foreseen ...

Powers of 2 are required if mass is to be distributed evenly in sets divisible by 2

It is possible that powers of 3 may be required for sets divisible by 3 ... I'll have to investigate.

What seems possible at this early stage of analysis is that a design intended to allow 36 Starships in the perimeter may not allow for a large number of balanced sets with fewer members.

Edit#2: After working with printouts of the 36 tooth Spur Gear, overlaid on the sketch of a Big Wheel habitat, I've concluded that the load master would have six options:

1) Set 2 Starships in opposite sides of the wheel, with a separation of 180 degrees
2) Set 4 at 90 degrees
3) Set 6 at 60 degrees
   See Edit#3 below for 40 degrees
4) Set 12 at 30 degrees
5) Set 18 at 20 degrees
6) Set 36 at 10 degrees

These distributions apply to the outer docking bays.

Edit#3: All the configurations shown above have the feature that a line between the docking cradles on opposite sides passes through the center.

7) A configuration that works is that with 9 Starships distributed every 40 degrees. 

The current total of possible configurations is seven: 2, 4, 6, 9, 12, 18 and 36.

Similar considerations would (no doubt) apply to inner docking rings.

Edit#4: The simple equation: Acceleration = Velocity Squared divided by Radius leads to an insight (for me at least) ... Centripetal force varies inversely with the Radius.  A habitat rotating at 4 RPM, with a radius of 56 meters, will provide 1 g at the outer perimeter.  However, inboard, at a radius of 28 meters, the centripetal force will be exactly half a g.  Thus, it will be (relatively) easy for a booking agent to inform potential passenger representatives of the amount of simulated gravity they will experience at a particular location in a structure.  Presumably a full 1 g experience will cost more than a Mars g level, but for some passenger groups the Mars level may be worth bidding for.

(th)

Last edited by tahanson43206 (2020-08-20 07:00:05)

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#65 2020-08-19 22:46:39

kbd512
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Re: Big Wheel Gyroscope Space Transport

tahanson43206,

You don't need that many Starships for a 1 hour wait and 8 minute flight to orbit.  A single Starship can feasibly accommodate 500 pax for a brief flight.  Starship has about as much pressurized volume as an Airbus A380.  An A380 can seat 500 pax, so this vehicle should also be able to do that.  Putting that many people in a single vehicle for a Mars reentry is a serious risk and they still have to have some place to live when they arrive on the surface, which is why I suggested the Cygnus PCM as both an escape vehicle, one-time reentry vehicle, and a new "Mars home" following successful touchdown to accommodate couples or families after attachment to a larger base and burial to provide radiation protection.  New Martians need a standardized "home" that maintenance crews know how to service.  We already know that an Aluminum cylinder is a long term viable orbital home from our experience with ISS, so the Cygnus design should be durable enough to assure a 20+ year service life.  It might take 20+ years to construct very large subsurface pressurized habitats and we're starting from nothing, so temporary housing is required.  Maybe there's a better way to do that using local materials and landing lots of colonists in Starships, but pressurized volume is at a premium and Starships will have to remain at Mars and conduct many up/down ferry flights to pay for themselves.

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#66 2020-08-20 07:17:31

tahanson43206
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Re: Big Wheel Gyroscope Space Transport

For kbd512 re #65

First, thanks for contributing to this new topic, which is itself a branch from RobertDyck's "Large Ship" topic.

As a reminder, it was your vision of a rotating habitat in your Large Ship design that led to RobertDyck's presentation of the Gyroscope Video that led to the Big Wheel concept.

Your observation about the capability of Starships to deliver 500 passengers to orbit is (to me for sure) breath taking << grin >>

My understanding is that Mr. Musk is thinking about sending 100 passengers in a Starship to Mars.    That seems ambitious to me, but people have survived being packed together in long ocean voyages for centuries.   

Your thoughts about the accommodations for passengers who arrive at Mars are interesting and thought provoking.

While I am concentrating on trying to work out what a Big Wheel would look like, I appreciate having other NewMars members taking on other aspects of the total experience that await a prospective passenger a few (Earth) years from now.

SpaceNut has been talking about his concept for a "Toehold" settlement in past posts, including in My Hacienda.  It seems to me there is some correlation between your thoughts about temporary housing on Mars for new arrivals and whatever SpaceNut has in mind.

For SpaceNut ... if you have a topic in mind where discussion of temporary housing for new Mars arrivals would fit, please let us know.  The topic will become increasingly urgent as the capability to deliver thousands of passengers to Mars becomes viable.

One option ** is ** to lay a landing Starship on its side.  In that case, the passengers would have purchased a share in the venture along with their transportation, and their initial home will be the same structure they just experienced for six to eight months of flight.

As a reminder for forum readers who are not familiar with the contents of ** this ** topic, it is anticipated that Starships would lie horizontally in their cradles inside the Big Wheel rotor.   The Starships in cradles in the outer perimeter would experience 1 g of simulated gravity.  Those inboard would experience proportionally less simulated gravity.    I am currently working on the second version of a model of what a cross section of the Big Wheel rotor would look like. The first attempt used a generated 36 tooth Spur Gear, overlaid on a circular pattern representing the cross section of a Big Wheel rotor.  However, I've learned that Fusion 360 can generate a polygon of 36 sides, so I'm going to try that in hopes if provides better control for placement of circles representing Starship cradles.

(th)

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#67 2020-08-20 16:32:10

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,852
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Re: Big Wheel Gyroscope Space Transport

Temporary housing: I had always envisioned exploration first with Mars Direct. Then Mars Homestead using a set of 4 Mars Direct habitats: 3 with 4 settlers each, the 4th as a backup and filled with tools and supplies. The habitats would be temporary housing while constructing a permanent base using in-situ resources. Since each hab has accommodations and life support for 4, sending an extra habitat provides additional backup. Each hab would carry one rover, but the additional habitat would carry a compact track loader instead. Once complete, this base could double in size to accommodate 24 crew. Then that crew would build housing for 100 more settlers: in preparation for the first SpaceX Starship.

Click for large image: 4500x2649 pixels, 3.29MB
normal_MHP-4FC-Image001.jpg

Click image for Bobcat sales video from a 2020 trade show. All electric compact track loader.
maxresdefault.jpg

::Edit:: Video talks about the new "all electric" having ball-joint actuators instead of hydraulics. Older electric vehicles still use hydraulics for lift and tilt, and attachments. This raises the question if which is better? The following link talks about hydraulic fluid.
https://www.sealingandcontaminationtips … lic-fluid/

For hydraulic systems working under operating temperature range –40 to 100° C with a maximum temperature range –54 to 135° C, mineral based hydraulic fluids are preferable. For higher operating temperature applications, fire resistant synthetic hydraulic fluids are more suitable. However, these fluids become highly viscous below –20° C.

Mars is cold. Mars weather over 3 days recorded by InSight lander:
insight_marsweather_white.png

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#68 2020-08-20 17:09:35

kbd512
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Registered: 2015-01-02
Posts: 7,607

Re: Big Wheel Gyroscope Space Transport

Robert,

That all-electric Cat looks like it might serve our purposes, but recall that Lithium-ion batteries are equally unusable at -40C, much less any colder temperatures, meaning they can only be discharged at a tiny fraction of their normal rate and, more or less, can't be charged at all.

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#69 2020-08-20 18:50:26

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,852
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Re: Big Wheel Gyroscope Space Transport

kbd512: Um, good point. So... plutonium heaters, like those used by Spirit and Opportunity to keep their electronics warm?
220px-RHU_parts.jpg

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#70 2020-08-20 19:16:33

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

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#71 2020-08-20 20:07:46

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

Using a 36 tooth Spur Gear as a template, I have laid out a model of what the outermost string of Starships would look like in a loading diagram.  This model is configured so that the 56 meter Radius line passes through the middle of each Starship.  If the Starships are configured so that there is a floor at that position, then passengers walking on the floor would experience 1 g of simulated gravity.

yMzg0Lc.png

It is easy to see (by inspection) that manual placement of the cradle circles was performed using simple mouse movements in Fusion 360.  I am still a novice, and am (currently) unable to perform (what I understand is possible) parametric placement of objects.  However, for the purpose of visualizing what the Big Wheel design would look like, the imperfect model is (or at least should be) sufficient.

Future development is currently planned to show interior rings of Starships.  I am struggling (a bit) with the needs of the engineers who are going to be tasked with designing the girders to bear the tension and compression loads of a vehicle on this scale.  Placement of the next ring of Starship cradles is dependent upon a guess as to the amount of distance/radius needed by the structure.  I ** think ** we have practicing engineers in the active membership, so it is possible one of them (or the more the merrier) can provide a sense of what known materials and fabrication techniques can deliver in what volume.

In the mean time, I'm leaning toward allocating 10 meters between rings of Starship cradles, to provide plenty of room for structure.

That volume can most certainly be used for storage of supplies needed by the passengers on a six to eight month voyage (or a two year one for those not staying on Mars).  Supplies would include fluid and solid consumables, as well as replacement parts for all the machinery on board the Starships themselves, and the Big Wheel itself.

While the simulated gravity in the interior Starships would be less than 1 g, it will still be greater than Mars until the ring at 21 meters is reached.

Edit: Locations contemplated 2020/08/21: 56 meters for outer ring, 46 meters next inboard, 36 meters next inboard, 26 meters next inboard. (Near Mars gravity)

As a reminder, since a number of posts have been added to this topic, here is an early model of the Big Wheel Transport vessel:

YdVeJOS.png

(th)

Last edited by tahanson43206 (2020-08-21 09:19:56)

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#72 2020-08-20 20:12:53

SpaceNut
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Posts: 29,310

Re: Big Wheel Gyroscope Space Transport

The plate is in the plane of the floor if the ship nose docks to the holes...which means all objects are at a right angle to that spin is the wall of the cabin and not its floor

merry-go-round-4827325.jpg

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#73 2020-08-20 20:22:42

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

For SpaceNut re #72

Thanks for taking a look at the diagram of the side view of a Big Wheel habitat.

You are right that the concept I'm pursuing is to allow each Starship to nudge its way into the cylindrical cradle for a ride to Mars.

Here is an example of how a Starship might be configured to provide a floor for passengers during flight:

images?q=tbn%3AANd9GcTIlo3LMkDTGLUIbAWJpsZFjQJb4Lsx-aky-A&usqp=CAU

If each Starship holds 100 people, then a fully booked Big Wheel would accommodate 3600 passengers and crew.

As I add rows for docking ports, the capacity of the habitat will increase.

The strength of the structure, and the power of the propulsion unit will need to increase as the loads increase.

Nuclear propulsion is looking more and more attractive for a vessel on this scale.

(th)

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#74 2020-08-21 09:10:01

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

For SpaceNut re topic ...

If you have time, here is a list of Ferris wheels that exist on Earth in 2020.  I would certainly appreciate addition of images of these devices in this topic.

The largest makes the Big Wheel look like a piker!  It is encouraging to see that the size demanded by Physics is proven to be quite achievable on Earth, using existing technology and materials!

World's tallest Ferris wheels
Name    Height m (ft)    Completed
High Roller    167.6 (550)    2014
Singapore Flyer    165 (541)    2008
Star of Nanchang    160 (525)    2006
London Eye    135 (443)    2000
29 more rows

Ferris wheel - Wikipedia

Please note that the Big Wheel design started at 112 meters diameter, but I have increased it to 114 meters to accommodate 36 Starships, which is a "magic" number for load balance.  Building cradles for 36 Starships provides opportunities for smaller numbers: 2, 4, 6, 9, 12, 18 and 36. 

Thus, the first version of this vessel could be built to deliver just two Starships to Mars with a minimal framework, and simple chemical propulsion.

A step up to 3 Starships would provide a basis for the "Tri-Cornered Hat" model, which would (or at least should) appeal to the public in advertising.

Edit#2: for SpaceNut .... here is a link to a web site that (apparently) lists organizations that design and build Ferris wheels

Edi#1t: I'm going to try for allocation of Starship cradles to the rings as follows:

Ring 4 (outer) 36
Ring 3 - 18
Ring 2 - 12
Ring 1 - 9

These numbers are optimal for load distribution flexibility (according to my analysis to this point).  A review by others may well reveal better plans, and I'm looking forward to making changes to improve the design as feedback comes in.  Development of Big Wheel is intended to be an Open Source collaboration, with specifications for best practices available to anyone and everyone with access to the Internet.

(th)

Last edited by tahanson43206 (2020-08-21 11:53:13)

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#75 2020-08-21 09:35:04

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Big Wheel Gyroscope Space Transport

Call for Participation:

Design of the Big Wheel Gyroscope Space Transport is intended to be an Open Source collaborative venture, with results available to anyone with Internet access.

The design flows from one simple fact of Physics, as pointed out by GW Johnson elsewhere in the NewMars archive.

There is need for support and assistance by persons with the following skill sets, and many more besides as the project moves forward:

1) Structural engineers
***>> aerospace engineers (suggested by kbd512)
***Mechanical engineers -- for the many moving parts, including the all important main bearings at the junction of the axle with the yoke.
2) Chemical engineers
3) Electrical engineers
4) Electronics specialists
5) Human factors specialists
6) Materials specialists
*** There is another category of speciaties ... those that would be needed to plan and operate in flight services
7) Gymnastics instructors (Mars level simulated gravity would be better for learning tumbles, which can then be practiced at 1 g)
8) Medical practitioners (A complement of 3600 people would be sufficient to justify a dedicated Starship for medical support)
9) Maintenance practitioners (A dedicated Starship could be allocated to manufacture of parts (3D/CNC) and maintenance support)
10) Ship's crew ... Command, Navigation, Maintenance

SearchTerm:CallForParticipationBigWheel

I will be happy to add specializations to the list above as suggestions come in

(th)

Last edited by tahanson43206 (2020-08-21 11:44:55)

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