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Bill Harris
Going beyond the desktop model of a Rover, I'm building a scale model Rover at 1:4 scale. There is an abundance of photographs of the Rovers and the US Patent Office website has accurate line drawings in the patent files of the Rover. Go to the USPO website and search for D487,715 and D488,093 .

The first step is to build the Warm Equipment Box (WEB), which is the core of the Rover. At 1:4 scale, the WEB is 8.5" long, 5.5" wide and 4" high. The attached images are the initial, rough build of the WEB and the Rover Equipment Deck (RED).

I'm playing with the idea of making this a functional, radio-controlled scale model of the Rover, but this may be too much of a leap making it pretty _and_ functional. What I may do is make the display scale model first, then a non-scale workable model for R&D and then a working scale model.

I'm working on making realistic-looking solar cells. The actual dimension is 4cm x 2cm, which is 10mmx5mm at this scale, and there are 1100 of 'em. My first guess for material to surface the solar cells with is 1/4" magnetic tape (like videotape); it has a reasonable color and bright luster. Ideas and suggestions are welcome.

--Bill
RNeuhaus
The cover to imitate the solar panels, I think the best idea is to go a bookstore and ask him and he might have a better idea of that! My idea is to put in many strips of roll picture camera and it might look alike to solar panels.

Rodolfo
odave
QUOTE (Bill Harris @ Jan 8 2006, 09:45 PM)
I'm playing with the idea of making this a functional, radio-controlled scale model of the Rover
*


Ooooo - how about going even further and adding some automatic control? You could conceivably do it with the LEGO Mindstorms RCX brick. It's relatively inexpensive and easy to program, though with one RCX brick you are limited to three inputs and three outputs. ISTR people making multiple RCXs talk with each other over an IR link, which would get you more I/O. And you'd probably need to build some interface electronics to make the outputs control bigger motors. And there's also a vision kit that accepts input from a webcam, so that will cover your FHAZ/RHAZ system smile.gif

I'd love to work on a project like this, but I'm afraid my wife would come out to the garage, cross her arms, tap her foot, and remind me of all of my current "Honey-Do" items that aren't getting attention.

Please accept my vicarious participation wink.gif
Tesheiner
QUOTE (Bill Harris @ Jan 9 2006, 03:45 AM)
I'm working on making realistic-looking solar cells.  The actual dimension is 4cm x 2cm, which is 10mmx5mm at this scale, and there are 1100 of 'em.  My first guess for material to surface the solar cells with is 1/4" magnetic tape (like videotape); it has a reasonable color and bright luster.  Ideas and suggestions are welcome.
*


Maybe printing the re-scaled solar cells on glossy paper, or also normal printing paper but covered with a plastic protection?
djellison
they need to have quite a bit of depth to them though - they're a few mm thick - and they have two 'levels' to them, with the little red corner on them etc etc smile.gif

My suggestion would be very dark blue or black acrylic sheets, cut to appropriate shapes, and then two stuck together to allow that little corner to stick out smile.gif

If I ever got round to something like this - I'd spend months adding all the little wires to and from the solar arrays smile.gif
Doug
PhilCo126
Won't be easy to make the arm and Athena science suite instruments ... Looking forward how You're going to do those parts.
Good luck ! smile.gif
helvick
QUOTE (Bill Harris @ Jan 9 2006, 03:45 AM)
I'm working on making realistic-looking solar cells.  The actual dimension is 4cm x 2cm, which is 10mmx5mm at this scale, and there are 1100 of 'em. 
*

Do you know this for certain? Thing is I've counted em and I get ~507 cells and I figure the most likely dimension is 8cmx3cm yielding an actual cell surface area of 1.21 m^2.

I'd love to know what the exact dimensions actually are.
Bill Harris
The solar panels are going to be an interesting challenge. At 1/4 scale each panel "wing" is going to be about 15"x5" and the individual solar cells will be 0.4"x0.2" (10mm x 5mm), so it is large enough to be workable.

If you'll look at the panels, the solar cells are arranged in groups of cells, say
10-by-2 cells attached to the top odf the panels. Breaking it down into groups like this makes it quite manageable-- I've taken a USPO line drawing and have marked off the panels into groups. I'll make pieces the size and shape of each group out of 1/64" plywood and glue the individual solar cells made of 1/64" ply to the groups and then glue the groups to the panel wings, thereby giving a 3-D quality to the assembly.

And, yes, individual wires from each cell is an option. Fine copper wire can be salvaged from small transformers, and glued and painted. I want the solar panels to look detailed from 6" away.

The nightmare will be all the bundles of wires around the WEB; there is minimal photo documentation of them.

But I'll tackle each new detail as it comes up; this is what makes modeling a challenge.

I'm more and more inclined to concentrate on a detailed display model initially, and develop a non-scale but functional rover as a parallel project. There are a lot of constraints added by the scale provision; once I get scale figured out and functional debugged, it will be easier to combine the two.

--Bill
djellison
QUOTE (Bill Harris @ Jan 9 2006, 08:01 PM)
The nightmare will be all the bundles of wires around the WEB; there is minimal photo documentation of them. 


No harm in giving Steve and/or Jim a quick email, they're bound to have the odd photo that might be handy.

Doug
helvick
QUOTE (helvick @ Jan 9 2006, 08:28 PM)
Do you know this for certain? Thing is I've counted em and I get ~507 cells and I figure the most likely dimension is 8cmx3cm yielding an actual cell surface area of 1.21 m^2.

I'd love to know what the exact dimensions actually are.
*

Just following up. I counted them again very carefully and now get 499. And by taking the published dimensions of the rover (1.6m x 1.2m for the deck) and doing al take off of about a dozen cells scattered around the deck I get an average width of 6.5cm and height of 4.0cm with an error of +-5%.

There was a lot of tweaking of the cell strings - only about 250 or so are actually placed in continuous strings of 10-13. Damn fine tiling job that. :-)

I would love one of those wotsits, err the-document-who-shalt-not-be-named. Oh well.
Bob Shaw
The Yahoo! Space Modeler's Forum is probably worth a look, I've not visited it for a while but there were certainly some similar projects (including a Lunokhod 2) being discussed there.

http://groups.yahoo.com/group/space-modelers/

http://groups.yahoo.com/group/space-modele...s/Lunokhod%202/

Bob Shaw
Bill Harris
Helvick, our messages crossed in the aether:

I got the solar cell/panel dims from "MER Technical Data" at

http://hobbiton.thisside.net/rovermanual/

QUOTE
3.1 Solar arrays:
The MER solar arrays are composed of 55 parallel strings of 20 cells each of 2cm x 4cm GaAs/Ge cells. Each string within the array is diode isolated. The total solar array area on the MER is 1.2 square meters.


55x20 is 1100. I drew the "solar cell groups" and the 4x2 cm seems to match those footprints reasonably well. But I'll double check those cell dimensions from the USPO line drawings.


Modeler's Forum? Hmmm, I'll check that out.

--Bill
helvick
QUOTE (Bill Harris @ Jan 10 2006, 02:43 AM)
http://hobbiton.thisside.net/rovermanual/
55x20 is 1100.  I drew  the "solar cell groups" and the 4x2 cm seems to match those footprints reasonably well.  But I'll double check those cell dimensions from the USPO line drawings.
*

That number is from the "Power Aware Computing and Communication" document and dates from 2000. The description was probably valid at the time but the details were significantly reworked before the rovers flew. 1100 Cells at 4x2cm would give 0.88m^2 of cell surface area which is definitely too low, such a panel would have had a peak power output of around 600-650 Watt hours per day. There are definitely only ~500 cells though see the attached crudely tagged Spirit deskpan.
Click to view attachment
The USPO Line drawings that I have are undimensioned which is a bit of a pain. Adding some approximate dimensions to them given that we know some precise values (like the Pancam\Navcam separation distances should be doable.
Bill Harris
Whew, that took some work. I'm using a similar deck pan, and I'll add yours into the equation. I don't think it matters what the _exact_ individual cell size and count is, I'll delineate the several cell groups, and see what the cell size is from that measurement.

Based on that MER tech pamphlet and other sources, my dimensional reference is that the WEB is 34" long, 21.6" wide, 14.4" deep and the RED is based on an equilateral triangle 48.8" on a side. Other measurements confirm that these dims are close to correct. If not, it's what I am using, and I'll proportion everything else to fit (it may end up being 3.957:1 instead of 4:1).

Knowing a couple of key dimensions on the line drawings I can carefully measure components using a dial caliper (measures to .001", which is "empty accuracy") and using the reference dims I can proportion everything else.

Thanks for the feedback.

--Bill
dvandorn
Reminds me of when I was 14 years old, and bored to death one winter day -- I took my 1/48th-scale Apollo Lunar Module model and started taking measurements here and there... and before I knew it, I had constructed, out of cardboard, a 1/6th-scale Descent Stage main body. Using a school ruler and my knowledge of scaling equations, I did all the math in my head and measured out the entire LM.

I was rather proud of that scratch-built model, though it went the way of all things many, many years ago. Its landing gear could be stowed and the supports all worked properly, it had a deployable MESA table, complete with a tiny B&W TV camera model stowed in the MESA, and the SEQ bay doors opened up, too. There was even a tiny canister attached to the ladder on the front leg that contained a 1/6th-scale American flag, complete with two-piece flagpole and a stiffening rod to hold the flag out.

It was all made out of cardboard and tin foil, of course -- esxcept I *did* use some old, frayed tinkertoys to reinforce the landing legs. Just think of it as doweling placed inside form-wrapped cardboard tubes.

I must say, I had a great time building it. I'm sure you'll have a great time building your MER model, too!

-the other Doug
Bill Harris
Oh, yes, I've been building plastic and cardboard-and-stick models since I was a pre-teen. I'm convinced that any child should be taught (or permitted) to build things from an early age, it teaches great hand-eye-brain coordination and a spatial sense.

I'm already having fun hammering the details out. Cut out the rough blanks for the solar panel wings and tailpiece last night.

--Bill
AndyG
QUOTE (Bill Harris @ Jan 9 2006, 08:01 PM)
I'll make pieces the size and shape of each group out of 1/64" plywood and glue the individual solar cells made of 1/64" ply to the groups and then glue the groups to the panel wings, thereby giving a 3-D quality to the assembly.
*

Hi Bill!

Given that the panels aren't quite rectangular, and you're considering thin plywood for the basis of these, and there's many, many of them: have you looked into CNC options for getting these cut? Or you could look into photoetching them in bulk?

You'd end up with all you'd need and as accurate as you wanted, without the hassles of having to hand-form hundreds of the little bleeders.

Just a thought (from a ship modeller and part-time UMSF poster).

Andy
Bill Harris
I checked those reference dimensions that I noted in Post#1 and Post#14 against another reliable source, and the dimensions of the Warm Equipment Box and the Rover Equipment Deck accurate as stated:

WEB: 33.4"L x 21.8"W x 14.9"D
RED: Based on an equilateral triangle 49.9" on a side.

I'll sit down tonite and figure an accurate size for the individual solar cells. I'll bet that Helvick is correct, but I want to double-check.

Andy, I am looking at options for cutting the solar cells. Cutting out 500 by hand is the Slobovian method, and gluing them into groups is going to be worse. I have an airplane model that I've got "in the works", and I could send the thin plywood panels for the solar cells off to the laser-cutter that is going to cut the wing ribs. And photo-etching is one option, too.

--Bill
Bob Shaw
Bill:

Or, print them out and laminate them, perhaps with a couple of layers...

Bob Shaw
PhilCo126
Please keep adding photos as You progress ... an interesting project ! wheel.gif
Bill Harris
I'll keep updates on this project.

BTW, in the Yahoo Group that BobShaw mentioned one current thread is modeling the New Horizons spacecraft.

http://groups.yahoo.com/group/space-modelers/

--Bill
djellison
I'm making an NH with the HGA from Spacecraft Kits as a basis - it's totally the wrong shape though smile.gif It's the thought that counts biggrin.gif

Doug
dvandorn
For its final incarnation, Bill -- you know, the one with motorized wheels and moving IDD -- might I suggest that some of the solar panels might be *real* solar panels? Charging a battery located in the WEB, that would power the wheels and the radio system you'd use to drive it...?

Heck, you could even use the LGA as the antenna for its radio system.

And, of course, you need to put a few webcams onto the thing -- maybe below the deck, a couple of each facing forward and backward? And maybe, I dunno, four separate lenses on top of the PMA mast? I bet you could arrange some mirror assemblies.

Now, let's talk about launch vehicles...

biggrin.gif

-the other Doug
Bill Harris
QUOTE
For its final incarnation, Bill -- you know, the one with


Yes that would be most excellent! I need to start checking around in robotics forums to see what technology is available.

Here is a photo of the roughed-out RED (Rover Equipment Deck) and the solar panels. To give an idea of scale, the side panels (the "Wings") are about 16" long and 5" wide.

--Bill
Bill Harris
QUOTE (helvick @ Jan 9 2006, 04:57 PM)
Just following up. I counted them again very carefully and now get 499. And by taking the published dimensions of the rover (1.6m x 1.2m for the deck) and doing a take off of about a dozen cells scattered around the deck I get an average width of 6.5cm and height of 4.0cm with an error of +-5%.
*


Just a followup to Helvick's followup: measuring solar cells on images of deck pans I get 7.0 cm x 4.0cm (2.8x1.6 inches). This works out to 0.70" by 0.4" for the 1/4 scale solar cells, which is not that bad a size to work with.

--Bill
Bill Harris
Couple of color questions:

On the Sundial/Calibration target, what are the reflectance values of the white and two gray rings in the center of the dial face? I'm presuming 100%,50%,25% or 100%,75%,50% but I'm not really sure. I've looked for an in-depth paper on this Pancam calibration target, but can't find anything detailed.

What is the color of the top of the Rover, the RED and solar panel wings? I would presume a dark gray, but calibrated images from early Sols suggest either a dark "olive" or a dark "brownish" color.

--Bill
Airbag
QUOTE (Bill Harris @ Jan 16 2006, 09:35 AM)
Couple of color questions:

On the Sundial/Calibration target,  what are the reflectance values of the white and two gray rings in the center of the dial face?


This link suggest 20, 40 and 60% for the gray rings:

http://www.highmars.org/niac/education/mer/mer00.html

Now the real question is - how will you ensure those values on your model, and perhaps more importantly, how could anybody tell? smile.gif

Airbag

PS If you can find a "top down" picture of the target, you could just scale it as appropriate for your model and print it out perhaps? Saves a lot of work.
Airbag
As it happens...

http://planetary.org/mars/mer_marsdial_nyelabs.pdf

I think that may work just fine for your scale model!

Airbag
djellison
Also - http://www.planetary.org/rrgtm/press-photos.html
smile.gif

Doug
Bill Harris
Thanks a lot, I don't know why that didn't show up on my first Google search.

Those published gray values give me a good starting point. A photographic standard gray card is 50%, and I can figure out how things _ought_ to look from that point.

--Bill
PhilCo126
I believe there're replica's of these Lego things as well as the Columbia logo disk is available (saw it on eBay I believe) huh.gif
Bill Harris
I've been drawing and cutting out parts. Here is a Rover mystery part: any guesses what part this is?

--Bill
jamescanvin
QUOTE (Bill Harris @ Jan 19 2006, 02:17 PM)
I've been drawing and cutting out parts.  Here is a Rover mystery part: any guesses what part this is?

--Bill
*


OK I'll bite...

Solar cells on top of WEB (as opposed to those on the "wings"), hole is for the UHF antenna?

James
djellison
HGA gimble assembly smile.gif

Changed my mind, IDD shoulder joint.

Doug
Bill Harris
We have a winner: it is the solar cell carrier on top of the WEB.

The HGA gimbal and the IDD arm are challenging pieces, but that will be another story...

--Bill
djellison
I've been Out MER'd smile.gif

Doug
general
Nice project, Bill. smile.gif

suggestion: could you add a 12 in/30 cm ruler or something in your pictures, so that we can get a sense of scale? unsure.gif cool.gif
Bill Harris
Good idea. I'll add a virtual ruler to the existing images, and include a scale with future images.

This was really an obscure part, Doug. I didn't realize how intricate it was until I started tracing it out from images and drawings.

The difficult and critical part of this will be the solar cells: they are intricate and have been a visible and well-known part of the MER imagery. The PanCams and Rocker-Bogey will permit a little artistic latitude, but the topside will have to be just-so.

--Bill
Bill Harris
Here are thoughts on the solar cell arrays. This part of the project needs attention since their appearance is well-known andthey are very detailed and they will make-or-break this model's effect.

At 1/4 scale each individual solar cell will be 0.65x0.40 in size. Closely examining photos, they seem to be affixed to the Rover panels with a reddish layer; this is probably a double-sided tape adhesive which has to be flexible to keep the cell affixed over a great temperature range. I think that the "true color" is reddish. The solar cells are arranged in symmetrical groups and the groups are attached to the solar panels. The cells are in different orientations in the groups, probably for a parallel-series wiring arrangement. White wires connect the cells and groups.

What I propose is to make the 500 or so cells of 1/32" modeling plywood, and glue the individual cells to the cell groups, also of 1/32" plywood, and glue these cell groups to the four solar panels of the rover. The "background" cell groups will be the proper reddish color and the individual cells will be a dark greenish-grayish-or-blueish (whatever color I decide; I'm undecided at this point), with a bright, hard luster. This will give a total cell group thickness of 1/16" at 1/4-scale, which is a bit thicker than it should to be, but ought to give a good scale thickness.

I may get the 1/32" plywood cells laser cut, or I may do it by hand. Not as impossible as it sounds, you can stack 50 cells at a time and cut/sand en-masse.

--Bill
Bill Harris
More discussions of model solar cells at Mer Model For Your Desk.

--Bill
Bill Harris
The most critical part of the MER model project is proving to be the solar panels. They are quite detailed and will have to be accurate since they have been well-photographed.

Here is the test piece I made up for the model solar cell array. Each solar cell is some 0.6"x0.4" in size and made of 1/32" plywood. Instead of gluing the cells to the 1/32" solar cell group piece (as shown), I'm going to glue each 1/32" individual cell to the panel since that combined thickness of 1/16" seems too thick. This test piece will allow me to practice working with the solar cells and to develop realistic ways of painting and detailing the solar panels. The solar cells will need to be very dark grey or black but will need to be glossy; the solar panel 'body' will need to be a slightly lighter grey but a semi-matte (non-glossy, but not flat).

And yes, I know that I've got the wrong edge of the solar cells notched on the test piece. Chalk that up to a brainf@rt... smile.gif

I've also included an image of the right-front Rover solar panel, "squared up" using the perspective correction function in my image editor. This makes the view of the panel perpendicular instead of oblique.

Work continues... sheesh there are a LOT of details on this model!

--Bill
PhilCo126
Bill ... You're doing a great job !
ohmy.gif ohmy.gif ohmy.gif
Bill Harris
Thanks, Phil. The devil is going to be in the details on this project.

I have a couple of questions about some of the gadgetry on the deck. Attached is an annotated clip from Dilo's Spirit Self-Portrait.

1) This device is on the solar panels and it is a electrically operated latch to hold the panels closed during re-entry and landing. I could guesstimate the angles and orientation from MER images, but I'd like to have an image of the this device holdiing the solar panels closed. Know of such an image?

2 and 3, 4 and 5) These are the hold-downs for the Camera Mast. Same question as item 1: do we know of an image of then holding the Mast?

6) These are obviously hinges with geared electric motors used to deploy the solar panels. But I can't figure out why there is a hinge PLUS a separate hinge/pivot on the motor shaft. Know why?


Picky questions, but one has to be a nut for details on a scale model.

--Bill
djellison
well 12345 - there are lots of high res pics at the KSC Multimedia Gallery ( www.ksc.nasa.gov ) - go back to the 6 monhts or so before launch and there's lots of photos, including nice one's such as the Equipment Deck just on its own with things stowed etc

as for 6 - I dont thin the motor has a hinge, I think it's two halves, one is the motor, one the planetary gear to down-speed it to the shaft from the array.
Bill Harris
Ah, I hadn't looked at the KSC Gallery-- that makes sense since this is where the completed Rover was mated to the rocket. Thanks!

--Bill
brianc
Bill

I've found some good links to High Def photos of rover asembly process here on Wikipedia - also got some good technical descriptions

http://en.wikipedia.org/wiki/Mars_Exploration_Rover

Regards


Brianc
brianc
Also some good prelaunch photos here

http://www.redorbit.com/images/gallery/mar...11/2/index.html
helvick
Nice finds brianc

this shot clearly shows the panel motor\hinge assembly both on the fully open position on the rear panel and closed on the side wing.

Bill - I'm very impressed with your attention to detail.
Bill Harris
Between Doug, Brian and Helvick, I have a lot of "assembly" images now. Especially at the KSC image archive there are many images of the underside of the Rovers.

http://mediaarchive.ksc.nasa.gov/index.cfm and use ROVER as the keyword.

Thanks!

--Bill
brianc
IDD - detailed schematic
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