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#76 2020-05-22 20:28:09

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 18,576

Re: Balloon Landing System from Phobos to Mars

valid image file extensions of png, gif, jpeg, bmp all work

The first is a search results page of yours that displays images for the key words.
http://www.bing.com/images/search?q=ima … ORM=IQFRBA

The second link was a web page showing the how to get a volume
https://www.chegg.com/homework-help/que … -q19029896

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#77 2020-05-23 06:52:47

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

For SpaceNut re #76

Thanks for the clarification about how to set up images in FlubBB ...

Just FYI ... I have found the documentation for FluxBB to be difficult to use at best, and nearly impossible to use to find something specific like this.

I'll try to remedy the problem in ** this ** forum by making your post above easy to find:

SearchTerm:ImagePosting
SearchTerm:HowToPostImage

I've been thinking about the design of the shape for a metal cushion to fit between links of Kevlar thread for the tether from Phobos.

Overnight, I realized that the square cross section of the base of the two halves of the shape must be 2 meters square, instead of 1.

The objective is to provide 1 meter of space for the ribbon coming into the intersection from 90 degrees with respect to each other.

With a 2 meter diameter for the cylinder, the resulting shape would have the following characteristics:

Diameter: 2 meters
Length: 2 meters
Flange width: 1/2 meter
Ribbon track width: 1 meter
Flange height: 1/2 meter
Flange diameter: 3 meters

SearchTerm:RibbonCushionGuide
SearchTerm:RibbonGuideCushion

I'll try to work up a 3D image in the next week or two.

A contribution by another forum reader would be welcome.

As a suggestion for anyone thinking of registering for the forum to help with this project (or any discussion) ...

Please consider making a straight forward comment or suggestion about a topic you are interested in.

The great (vast) majority of applications for participation in this forum are spam artists, or just work-a-day spammers out to place advertisements.

In order for your application for membership to stand out, please make it relevant to whatever discussion you join.

We have need of additional assistance with (just about) every branch of engineering, science and the practical arts, such as agriculture, construction and hundreds if not thousands of other disciplines.

(th)

Last edited by tahanson43206 (2020-05-23 06:54:29)

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#78 2020-05-25 11:36:26

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

Today I'm hoping to be able to show preliminary images of the design of a Cushion Guide to sit between links in a tether.

While the design is intended for the specific case of a Phobos tether, it could (presumably) be used anywhere a tether is needed.

If Lockbox displays an advertisement, please just dismiss it.  They need to make a return on their free services, so an advertisement is part of the deal.

CushionGuidejpg.jpg

Above is a jpg version of a first draft of a Cushion Guide shape.

Since the image did not display, here is the url to the image: https://www.dropbox.com/s/17ok0h8kok961 … g.jpg?dl=0

Below is a png version of the shape, from a slightly different perspective.

CushionGuideUnion.png

Since the image did not display, here is the url to the image: https://www.dropbox.com/s/1d81a8pp0glgb … n.png?dl=0

The design shows empty space inside the form.  That is an artifact of the method I used to create the object.

A future version should appear solid, as would be required for the tether application.

For purposes of the current study, the ribbon width is planned to be 1 meter, and the thickness will be dependent upon the number of threads needed to hold the tether and its load below that point.  A program to compute the required thickness is in development.

Edit#1: Here is a version with a bit of texture added:

CushionGuideTexturejpg.jpg

In case the image does not work, here is the url: https://www.dropbox.com/s/zp2gwu52bpjz7 … g.jpg?dl=0

Edit#1: SpaceNut has kindly provided the "secret" that allows FluxBB to display original content:

p.jpeg?fv_content=true&size_mode=5

The ** secret ** is NOT to try to use the link provided by Dropbox, but instead, to follow the Dropbox link to their site, and right click on the image.

Then, ** save ** the url they provide, and post ** that ** inside the BBCODE [ i m g ] and [ / i m g ]

(th)

Last edited by tahanson43206 (2020-05-27 07:54:05)

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#79 2020-05-25 13:12:10

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 18,576

Re: Balloon Landing System from Phobos to Mars

p.jpeg?fv_content=true&size_mode=5

p.png?fv_content=true&size_mode=5

p.jpeg?fv_content=true&size_mode=5

right click each image to get the properties of the image and select that for making them visible.

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#80 2020-05-25 15:25:04

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

For SpaceNut re Demonstration in Post #79

Thanks for posting the command you used (in the Housekeeping topic) 

I'll attempt to find a better site for storing images for display in the NewMars forum.

Continuing with discussion of the Cushion Guide design ...

I am planning to add solid attachment hardware to the shapes.  Right now I'm thinking of symmetrical distribution of attachment hardware at the four corners where the flanges intersect.  The attachment points would be used to secure light rail tracks which could be used by descending vehicles to maintain a steady rate of descent instead of plunging uncontrollably as would be the case if they were in free  fall.

(th)

Last edited by tahanson43206 (2020-05-25 20:50:07)

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#81 2020-05-26 08:29:25

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

This post is reserved for a report on progress planned for this Earth day:

1) Upload the Version 1.0 of the Cushion Guide shape to Shapeways and provide a link

    This will pass the design through the strict software review at Shapeways, and provide a way to see the image by rotating it using their display tools.

2) Return to the tether design program, which has been waiting patiently for other higher priority tasks

    The immediate objective is to complete a first version of the link builder, which will (if achieved) produce:
 
    a) Length of thread needed to hold the burden below this link
    b) Cumulative length of thread needed, starting with bottom most link
    c) Mass of thread for this link
    d) Cumulative mass of thread to this point

Detail: The computation of thread length is planned to be based upon a layer width of 1 meter, and thread diameter of 290 micrometers (Type #92 thread)

The radius of the wrap hub will be increased by 290 micrometers for each layer, to insure the length computation is correct.

The height of the flange is currently planned as 1/2 meter, so it will hold 1 meter / 290 micrometers or 3448 threads / 2 or 1724 layers

Each layer will hold 3448 * 2 * 13 kilograms or 89648 kilograms per layer using #92 Kevlar thread.

The mass of the payload needed by NASA is 40 Metric Tons.

A vehicle capable of delivering that mass safely to the surface of Mars is estimated to total 190 MT (using retro-propulsion) (see GW Johnson/Phobos topic)

Therefore the bottom most layer should be able to hold 190 MT plus its own mass plus a margin for safety.

The gravity pull of Mars is (about) 38% so the actual force exerted on the payload will be 72 MT and change

A single layer of Kevlar #92 thread can hold 89+ MT.

I think that two layers should provide a sufficient level of safety.  The tether must not only hold the dead mass of the descent vehicle while the operator waits for a suitable release time, but also allow for transient extra tension due to braking loads imposed as the descent vehicle slows after rapid (controlled) descent.

Critical review of this set of computations is not only welcome but most definitely encouraged.

***
Here is a design detail that I need help to understand ...

My first concept for the material of the Cushion Guide was to make the entire structure of Aluminum (Atomic Weight ~27).

However, the atomic weight of Carbon (~12) is attractive, and the mass of the cushions is going to add up.

Carbon can be crushed down to the density of carbon, but I doubt that will happen in this application.

What form of Carbon would be suitable for a filling of an Aluminum shape as shown in earlier posts for the Cushion Guide?

Edit#1: As of the morning of 2020/05/27, attempts to merge a mounting slab with the existing Cushion Guide shape have not succeeded.

Work on the program has remained in pending status.

Edit#2: A pesky problem with how boolean logic works was (apparently) solved today, by breaking the problem into parts.

Two of four planned corner bumpers are now installed in the 3D model.  I expect to finish later today.

(th)

Last edited by tahanson43206 (2020-05-27 09:05:55)

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#82 2020-05-27 14:53:41

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

For SpaceNut (and anyone else who may be interested) ...

Update 2020/05/28 ... the links which worked (for me) yesterday are not working today.
Update later the same day ... now the links are working. Perhaps there was something going on at Dropbox.

Design of the Cushion Guide for the Phobos Tether is coming along.  The design is not 3D printable at this point.  However, the visual image comes close to showing what I have in mind.

Using the technique shown by SpaceNut, these three views of the model should show up:

CushionGuideVersion25 only appeared for a day.

Notes 1:
This view shows the guideway for the ribbon coming up from below. The width of the guideway is 1 meter. The height of the flange is 1/2 meter.  The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.


CushionGuideVersion25 only appeared for one day.

Notes 2:
This overhead side view shows the guideway for the ribbon coming up from below, as well as the vertical rise for the ribbon descending from above. The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.


CushionGuideVersion25 only appeared for one day

Notes 3:
This view shows the guideway for the ribbon coming down from above, as well as the outer flange for the ribbon descending from above.  The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.


(th)

Last edited by tahanson43206 (Today 07:26:16)

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#83 2020-05-28 09:47:57

tahanson43206
Member
Registered: 2018-04-27
Posts: 2,591

Re: Balloon Landing System from Phobos to Mars

This post is an experiment to see if something happened at imgur.com

The path to the image included a subdirectory /a/ in the first use.

Today the path looks "normal"

Version 12 of CushionGuide

Perhaps imgur.com moved the image from a temporary directory to a permanent one.

Note for SpaceNut ... I also had to add .jpg to the link provided by imgur.com

Note#2 for SpaceNut ... I used the technique you suggested, of right clicking on the image as provided by imgur.com, and noticed .jpg was included.

For someone wanting to learn how to post images ... hang in there! 

Edit#1: This post was included in an update on Luf.Org, about the Phobos Tether.

https://luf.org/2020/05/28/kevlar-tether-for-phobos/

(th)

Last edited by tahanson43206 (2020-05-28 10:16:29)

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