When the antenna reaches the top of the canister, the ring hits an internal stop in the canister, which  prevents it from moving while the hub continues to travel up. This causes the root ribs to deploy as they are  pulled by the springs attached to the ring. The springs also add compliance to the system accommodating  for any small deviations in deployment of the root ribs.  The tip ribs are each deployed by a constant force spring in the mid-rib hinge. The tip rib spring actuates  once the root ribs have deployed far enough such that the tip ribs are clear of the horn.   Use of Additive Manufacturing  When fabricating the spring ring, which coordinates all 30 springs to the ribs, it was found additive  manufacturing was the most cost-effective approach and gave the best result for building this part. The  spring ring consists of multiple small holes through which extension spring hooks attach. Traditional  manufacturing would have been challenging as the spring holes would be at an angle, and thus hard to drill  with a small diameter drill bit. Further, the holes would have sharp edges, which would catch on the hooks  of the extension springs. However, by additively manufacturing this part, a full annular hole was created in  the spring ring, perfectly fitting the geometry of the extension spring (Figure 4). This made it function better  than a traditionally fabricated part.  Figure 4. An Additively Manufactured Sprin g Ring Allows for Unique Features  The component was printed of 304 stainless steel, and as additive manufacturing has been known to have  variable material properties, a stress analysis was performed and found the part had a factor of safety of  greater  than  10. Therefore,  material  property  variance  was  deemed  to be low risk enough  to not  require  testing of the additively manufactured parts. Perhaps the most exciting part about additively manufacturing  this component was that it was cheaper than machining the part traditionally. As material volume is the key  cost in additive manufacturing, and complexity is not a driver, this part required minimal material and could  thus be built  inexpensively.  This  also  provided  a good  example  of using  additive  manufacturing  for its  strengths  in creating  complex  features  which  would  be hard  to machine  otherwise.  While  additive  manufacturing is not the best option for many parts, for this one component, it had significant advantages.  Construction and Testing of the KaPDA Antenna  Three versions of the KaPDA antenna were constructed in series . First a prototype , then an engineering  model, and finally a flight unit was constructed.  Prototype  The firs t prototype of KaPDA was constructed to primarily verify the accuracy with which the antenna could  be buil t and test th e gas-powered deployment system . The prototype was a full fidelity prototype , which  used fligh t like materials.   To construct the antenna, first the 30 ribs and hinges were assembled. The ribs were then attached to the  hub. Mesh was stretched and tensioned over a parabolic mold, and then the hub with ribs were set on top  © 2018 All Rights Reserved. Government sponsorship acknowledged.  NASA/CP—2018-219887 366