Sunday, March 13, 2016

Unity

Unity (a.k.a, Node 1) was launched into orbit on December 4, 1998 aboard space shuttle Endeavour on the first shuttle mission to the ISS, STS-88. Unity was the first U.S.-built module to be launched, built by Boeing at the Marshall Space Flight Center.

Unity is made of aluminum and weighed almost 26,000 pounds at launch, inclusive of two Pressurized Mating Adapters (PMAs)  that were initially attached at the forward and aft berthing mechanisms.

Unity has a total of six Common Berthing Mechanisms.  These mechanisms allowed the station to expand in future missions to connect additional modules needed to provide living, experimental, storage, and various logistic functions.

Unity is part of ISS combo kit #1 from AXM.  This particular kit must be purchased.  The fee for this kit is well worth the price. In my opinion, it's a very small price to pay for the high quality and craftsmanship exhibited by all of AXM's kit designs on his site.

This particular kit is comprised of 5 pages: 1 page of parts containing the main Unity module, another page containing parts for PMA-1 and PMA-2, a page containing the parts for the Russian-built Strela crane, a page providing parts for the US-built Orbital Replacement Unit Transfer Device (OTD), and a page containing the Early Communication Antennas (ECOMM) graciously provided by AXM upon my request. The assembly manual for the main module and PMAs is 9 pages, with instructions for the Strela (4 pages) and OTD (3 pages) located in separate documents.

I started the build by cutting out the circular areas of the radial berthing mechanisms of the main body.



Following my established method for obtaining a flush fit at the seam, I cut off the glue tab for the main body part and then re-glued it to the back inside edge with a slight overlap.


I allowed the glued tab to dry and then rolled the main body part using a colored pencil to gently curve the paper and glued the section together at the tab.  I then undertook the tedious task of cutting out the 4 berthing mechanisms (many angle and curve cuts here).  AXM did a great job in designing these parts, providing a concave recessed look!


Anticipating future module connections to Unity, I decided to employ neodymium magnets for connection of modules to the radial and forward berthing ports (the aft port is permanently connected to Zarya via PMA-1). I glued two magnets to the inside forward and aft location of each radial berthing port.  


I cut out the forward and aft berthing mechanism caps and glued them to the main module.  I set a glue bottle on top of the assembly to obtain a flush join.


Next, I cut out the forward and aft end cap rings and flanges, assembled them (using the tab overlap technique for a flush seam), and affixed them over the berthing mechanism caps.


I then turned my attention to the berthing mechanism petals.  There are four petals located on each port. Having studied various photographs of the petal position when a module is berthed to a given port, I decided to color in the backside of each petal using the same color (beige) that is used on the front of each petal.


I scored the back of each petal at the bend point to ensure the proper lay of each petal in the un-berthed position.


I then affixed the petals to each berthing mechanism location and added the tool bag at the prescribed location on the starboard aft side of the module. 


I then turned my attention to the module's four trunnion pins.  These pins secured the module within the shuttle bay during its trip into orbit.  The pins actually protrude from the module surface, however the design depict them as two dimensional. I decided to embellish the model and add the pins (using 18 gauge insulated wire pieces), affixed on top of the thermal covers provided in the model kit.  I used additional insulated wire pieces to affix the early communication antennas to the port and starboard berthing ports.


Next, I commenced working on assembling the PMAs.  I first built the zenith and nadir multiplexer/de-multiplexer (MDM) units for PMA-1, along with the zenith MDM sunshade.  


I cut out the main PMA-1 body (many angled cuts to this piece) and scored the back side along prescribed fold lines.


I then cut out the PMA-1 base and docking ring.  I folded and joined the PMA-1 body, affixed it to the base, assembled the docking ring, and joined the ring to the PMA body. I then added the MDMs and the zenith MDM sunshade to prescribed points.


Moving onto PMA-2, I followed a similar assembly sequence as with PMA-1. I cut out the main PMA body, scored the backside, assembled the PMA body, affixed the body to the base, assembled the docking ring, and joined the docking ring to the PMA body. PMA-2 has two Grapple Fixtures located at the zenith on port and starboard sides of the unit.  I built both components and affixed them to the prescribed locations, adding a black wire piece to the center of each grapple fixture base in order to to add some 3-dimensional realism.





  
PMA-2 was moved to different locations a few times during the ISS assembly sequence. Anticipating the need to re-position this PMA in future assembly updates, I decided to affix the PMA using magnets. I glued two magnets to the inside lip of the flange on the zenith and nadir locations of the forward berthing port and another two magnets to the inside lip of PMA-2 at the same locations.


I then glued PMA-1 to the aft section of Unity, resulting in the following outcome.


After studying numerous photos of Unity taken during STS-88, STS-96, and STS-101, I decided to add additional detail to the module by adding the various power and communication cables and umbilical connections. First, I needed to come up with something to serve as the umbilical connections located on the PMAs and forward and aft edges of the module.  I decided to use the plastic insulation on some 24 gauge wire.  I painted a section of the wire using a white enamel sharpie.  Next, I scored individual sections of insulation at the prescribed length (based on the pattern printed on the PMAs) and pulled them from the metal wire.  I lost count after cutting 100 pieces!


I then affixed the tubular pieces over their printed counterparts on the PMAs.  I initially tried to glue the tubes atop each printed connection point for the connections located on the forward and aft edges of the module.  However, subsequent cable connections from the module edge to the PMA points resulted in repeated separation from the glue point.  I decided to push a small hole through the module at each connection point and countersink the tube into the hole with a dab of glue.  This approach worked perfectly!


I then proceeded to determine the exact cabling configuration by reviewing numerous photos.  I ended up producing a drawing of the cable configuration to assist with the implementation.


I used 28 gauge craft wire for the cabling.  I was unable to find wire in this gauge that was already coated white, so I ended up painting lengths of the bare aluminum wire using a white enamel sharpie. I was very impressed with the result of my research and labor to add this detail!

 

In addition to the trunnion pins Unity also has a keel pin which helped to hold the module steady in the shuttle bay during launch.  This pin was printed on the main cylinder and I wanted it to be 3-dimensional also. I fabricated the pin using 18 gauge wire and fabricated a mount for the pin using a scratch-built mount.


At this point the module is configured as it was during STS-88.  I fabricated a mono filament hanger with magnets for module display.


I then proceeded to build the ORD and Strela crane components which were added to the module during STS-96, and STS-101

I started with the ORD, building the component from the kit, initially adding a handle and paddle extension for realism, and later adding another handle and hand cranks.


The directions called for gluing the ORD directly to the PMA along the port side in horizontal alignment with the associated trunnion pin placement on the module.  I decided to fabricate a mounting nub and secure the crane on the nub to allow for movement of the ORD to various orientations.  I used a 1/16 inch piece of a cocktail toothpick for the nub and affixed the nub to the PMA using a small piece of wire inserted into the end of the nub and pushed into the PMA to better secure it. The nub was painted silver using a sharpie.



Next, I fabricated  the base of the Strela crane.  The ORD was then affixed to PMA-1 and the Strela crane base was placed onto the port-side grapple fixture on PMA-2, completing the configuration of Unity at the conclusion of STS-96.




I then worked on completion of the Strela crane.


During STS-101 the Strela crane base was moved from the PMA-2 grapple fixture to a new mount located on the zenith of PMA-1 and the crane boom was added. I added another nub for the PMA-1 crane location, embellished the crane by adding yaw, pitch, and extend/retract boom hand cranks, fabricated a grapple fixture for the crane mount point, and moved the assembled crane to the PMA-1 location, which resulted in the module configuration at the completion of STS-101.



I then transported Unity to my office and mated it to Zarya, where I added the last detail: a communication cable extending from Zarya to the starboard side early communication antenna.

Both modules are currently on display on one of my desks.  However, I soon plan to re-position them to the ceiling of my office.



Next up - Zvezda. Stay tuned!

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