Repairable Mars Lander Modification

[jeffyjeep]

In one of my previous threads I mentioned a possible thread on building a Mars Lander with serviceable "guts".

I have a Semroc Mars Lander of which I've completed the major sub-assemblies. I'm basing the modification on the ML procedural by Kenneth Jarosch's in the May/June 2008 issue of Sport Rocketry, but I'll probably be adding some of my own techniques. TBC

[tbzep]

I did a repairable build several years ago. I'll see if I can find the thread.

Found it.

http://forums.rocketshoppe.com/showthread.php?t=4137&highlight=mars+lander



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[tbzep]

BTW, Martin Marietta is no more. Are you going to go with custom Lockheed Martin decals?

https://upload.wikimedia.org/wikipedia/en/thumb/9/95/Lockheed_Martin.svg/800px-Lockheed_Martin.svg.png

[jeffyjeep]

Excellent! I was wondering how to do the bottom shroud. Now I know--if you don't mind me using your idea.

[tbzep]

Excellent! I was wondering how to do the bottom shroud. Now I know--if you don't mind me using your idea.
Absolutely! Use it and improve on it. :cool:

[dlazarus6660]

Great thread! Now I gotta dig my ML, finish it and fly it. :rolleyes:

[LeeR]

I recall the thread now that it has been linked and I read it again. This time I bookmarked it for my next Mars Lander build.

[jeffyjeep]

Alignment will be important in this model, so I've penciled witness marks onto the bottom disk and the body tube.

I then make pencil marks on the bottom disk to mark the outer edges of the landing gear housings, transfer the marks up the sides of the base, and into the edge of the base cavity.

I then slit a 1/2" wide strip of 3/16" thick basswood ("The Vixen" was able to get the bleeding stopped) and scrape a slight convex profile into one side of it with the Corian slab sovered with 220.

To help prevent the 3/16" basswood from splitting during it's end use, I slit a strip of .040" styrene and glue it onto the flat surface of the basswood strip with thick CA and clap it in place with clothespins. I use CA VERY rarely in rocket construction. I'm using it in this case only because of the dissimilar materials.

TBC

[jeffyjeep]

Now to use the plastic-backed basswood.

Using a piece of 1/2" angle aluminum as a fence, I cut the strip into (8) 1/2" blocks with a razor saw.

I then use the Corian sanding slab to make the bottom end very flat and I then scrape a bevel into the bottom edge to clear the fillet inside base ring.

Using mid-cure epoxy (15 minute) I mount the (8) blocks using the pencil lines as guides.

Time for a Scotch and an IPA. Good night. TBC

[jeffyjeep]

Now for some fitting.

After fitting the ascent assembly to the BT100 and center the LL through the passages I pencil a witness mark for alignment.

I then epoxy the ascent shroud assembly to the BT100 from the inside. TBC

[jeffyjeep]

Next I mark the center of the blocks and transfer the mark down the edge of the base and the underside of the base. I then slide the BT100 assembly over the base and transfer the marks onto the BT100. I then remove the BT100.

Next I use the smallest die on my leather punch and punch (8) holes through the BT100. I then reassemble the BT100 onto the base again and mark the center of each hole I just punched. I then remove the BT100. TBC

[jeffyjeep]

I then remove the BT100 again and using a pin vise with a .030" drill I bore a pilot hole at the mark and through the basswood block and the plastic backing.

I then reassemble the BT100 onto the base again, line up the punched holes with the drilled pilot holes and start (8) #2 x 1/2" round head sheet metal screws into the holes. I then tighten them all down.

Time for a Scotch and an IPA (both of which "The Vixen" has already put before me.) Good night.

TBC

[jeffyjeep]

I again slide the ML parts to together. I run a bead of epoxy onto the top bulkhead of the ascent section and register and hold the bottom bulkhead of the command module onto it until the epoxy sets. I then scarf the LL. TBC

[jeffyjeep]

Again I slide the assemblies apart and using the leather punch I punch (2) 3/32" holes into base disk of the BT100. I then place the bottom shoroud onto the bottom and the nozzle (no glue) and trace it's edge. I then use the inside cartridge of a ballpoint pen and mark the inside of the bottom disc of the bottom wrap for locations of the screw bosses. TBC

[jeffyjeep]

Now for the screw bosses of the bottom wrap assembly.

I stack (2) squares of 3/16" basswood (crossgrain) and epoxy them to the disk according to the locations determined by the previous pen marks. The bosses are just a BCH below the top edge of the wrap, so I epoxy a square of .040" styrene to each boss. This has the added benefit of helping to prevent splitting.

I then lay the bottom shroud back onto the bottom of the model and register it to the penciled circle and hold it tightly while I use the pen cartridge through the punched holes to mark the bosses for drilling. I then use the pin vise to drill the holes into the bosses. TBC

[jeffyjeep]

Now for the legs.

I attach the legs onto the mounting dowels and fish the rubber bands through the holes using a tool that's designed for clearing string and threads from the roller/brush of the vacuum cleaner and then secure them with the .75" long dowels. Obviously, when the rubber bands need to be replaced they'll have to go through the holes in the legs differently, but for now I'll leave them as is.

TBC

[jeffyjeep]

Next, I attach the bottom shroud assembly with (2) #2 x 1/4" long sheet metal screws from the inside of the bottom disk.

I now slide the top sections of the lander onto the "chassis" and run the (8) screws around the bottom rim to hold it on.

THE MOVING PARTS OF THE ML ARE ACCESSIBLE AND SERVICEABLE!

I still have some work to do on the BNC and I still need to mount the satellite dishes before I can paint the lander's body, but this will have to wait until I return from my week-long job in San Diego. TBC

[Shamous]

Wait a minute, you designed a tool for cleaning string and stuff from the roller of a vacuum cleaner? I want one of those!!!

[jeffyjeep]

Wait a minute, you designed a tool for cleaning string and stuff from the roller of a vacuum cleaner? I want one of those!!!

Thanks, but I'm not quite THAT inventive. The vacuum roller brush cleaning tool is from a high-end vacuum cleaner store. The lady that sold me my Sebo X4 included it gratis. I'll see if I still have the packaging for the tool--if I don't drown in San Diego! El Nino is causing some serious flooding.

Ya know, it's ironic that a city that's not below sea level and is on the pacific coast can't get rid of rainwater fast enough to prevent flooding.

[Ltvscout]

Thanks, but I'm not quite THAT inventive. The vacuum roller brush cleaning tool is from a high-end vacuum cleaner store. The lady that sold me my Sebo X4 included it gratis. I'll see if I still have the packaging for the tool--if I don't drown in San Diego! El Nino is causing some serious flooding.
Looks like an old dental pick will do the same job, for the vacuum cleaner. Dentists toss old picks all the time. Next time you're in getting your teeth cleaned ask them if they have any old ones you can have. I use them all the time for various projects.

[BEC]

Or even some sizes of crochet hooks.....

[jeffyjeep]

I'm back from San Diego now (I didn't drown.)

Now for some repurposing:

Since kit's faux satellite dishes have no concavity to them, they don't look "dishy' enough. Using the OLFA circle cutter, I match up the size of the kit's dishes and cut replacements from a ping pong ball that the dog had cracked.

The (2) disk blanks aren't quite round enough, so I then drill out the hole made by the OLFA's stylus large enough to accept the threaded arbor of the shaft of the Dremel's cutting disk. Then (on low speed) I sand the edges of the disk blanks until they're perfectly round and are the same diameter as the kit's disks.

I made it look easy in the photos, but it actually took me (5) tries and approx. (50) naughty words to make (2) stinking disks.

I hope "Micro Mutt" doesn't want her ping pong ball back. TBC

[tbzep]

I made it look easy in the photos, but it actually took me (5) tries and approx. (50) naughty words to make (2) stinking disks.
Yep. I planned on doing that very thing with my build, but decided it wasn't worth the effort considering the slight curvature can't be seen from more than 3 or 4 ft away. Painting the disk a contrasting color made much more difference in making it look like a dish. I'll give you high marks for perseverance, though. ;)

[LeeR]

You model will gain a lot of realism with the new curved disks. I guess you could say they are ...

High Gain Antennas ...

[jeffyjeep]

You model will gain a lot of realism with the new curved disks. I guess you could say they are ...

High Gain Antennas ...

Gaaah.......

That pun was VLF (Very Lame, Friend.) :D

[jeffyjeep]

Yep. I planned on doing that very thing with my build, but decided it wasn't worth the effort considering the slight curvature can't be seen from more than 3 or 4 ft away. Painting the disk a contrasting color made much more difference in making it look like a dish. I'll give you high marks for perseverance, though. ;)

Wait, there's more!

Wait until you see what I do with the pointy doo-hickey (collector?) in the middle of the dish! TBC

[tbzep]

Gaaah.......

That pun was VLF (Very Lame, Friend.) :D
Only a bubblehead or an old metal detectorist would use VLF! :p

[jeffyjeep]

Only a bubblehead or an old metal detectorist would use VLF! :p
Oh, I guess you might say that I'm in the...


.....wait for it....


.....wait for it.....


.....wait for it.....


.....wait for it.....


Loop. :D

[jeffyjeep]

...and now the SUPER REALISTIC looking dish assemblies are on the lander. All the dish needs is a red lightning bolt and it would be indistinguishable from an Andrew unit. :rolleyes:

Time for some booze. Good night. TBC

[jeffyjeep]

After gray and white primer coats, here's a weight check:

4.5 ounces (after zeroing the scale with the yellow Estes stand.) Not quite as heavy as I'd feared, but greater than the prescribed weight of 4.1 ounces. It won't be getting much heavier, but the parachute is not on in it yet either.

TBC

[jeffyjeep]

I promised a special treatment for the faux satellite dishes.

After the white enamel cured on the ML and the decals applied and dried (adding the NASA "meatballs" was my own idea) I raided "The Vixen's" (seemingly) inexhaustible glass bead supply and selected (2) TINY gold colored glass beads. I then epoxied them onto the dishes' center rods to simulate collectors.

The reveal should be tonight! TBC

[jeffyjeep]

To determine that this ML truly is repairable, I tested an alternative to the legs' rubber band shock absorbers.

If the original rubber bands ever break--and someday they will indeed if the model lives long enough, the replacements will have to be of a kind that can be attached to the leg without causing trauma to the mounting hole in the leg. Using a length of 1/8" rubber shock cord I tie it into a loop and then pass the loop through the hole in the leg (next to the existing rubber bands because I'm leaving them on.) I then work the lark's head down to the exact bottom of the leg dowel and then fish the rubber cord loop through the hole in the base just as I would with the double rubber bands.

This was a test only. I'm leaving the rubber bands on and I'll only replace them when it's time.

TBC

[jeffyjeep]

The Mars Lander with Repairable Landing Gear Guts (or MLRLGG) is finished!

Operational Configuration:

[jeffyjeep]

Service Configuration!

Thanks for watching.

[jeffyjeep]

BTW, the final weight (less parachute, wadding, and motor:) 4.7 ounces.

[jeffyjeep]

I think I’ll do this again——-very soon!

[ghrocketman]

I'm going to incorporate your Mods in the next one I build.
I have 3 kits sitting.

[LeeR]

I agree with GH, your mods will be used on my next.

In looking back on your repair post, I noticed the Olfa Circle Cutter. One has been on my Amazon Wish List for a long time. I’ll move it to the cart next time I order. (With Prime, its so easy, that could be as early as tomorrow...) :)