Page 72: of Marine Technology Magazine (September 2022)

MTR 100

Nikki Arm and Brianna Roberts Kevin Hardy

Figure 15 Figure 16

Cal Poly-San Luis Obispo undergraduate students Mason An EdgeTech burnwire, rated for 100-lbs, can restrain a

Gariepy and Kyle Walsh test a Lifesaver release used to load of 500-lbs using the mechanical advantage of a deploy a baited arm on their lander DOV SEASTANG. Pelican Release.

I shared that idea in recent years with two Scripps gradu- presents other choices.

ate students and an undergraduate team at Cal Poly-San Luis A force multiplying lever can be used to increase the load

Obispo as a means to hold a baited drop arm in a retracted carried by a given burnwire or release element. A pelican hook position during their lander launch and descent, then release for example, is really a Class-2 lever, where the load and the the arm to rotate down to the sea? oor. They each adopted restraining force are on the same side of the fulcrum.

the idea and found it worked ? ne. In a careful study, the Cal Two releases may be used to hold a single anchor weight,

Poly students found all colors of lifesavers could hold up to providing a back-up release capability.

10-lbs (all broke at about 20-lbs), and would release between The ends of a “release chain” connect the two releases, form- 17-25 minutes in ? owing water, depending on the weight be- ing a “V”. With one end loose, a large steel ring link is placed ing carried. on the release chain. The ring link is comfortably larger than any link or shackle required by the release that maybe on the 3D printing ? lament end of the chain. The ring link is connected to the anchor 3D printing uses two kinds of ? lament. One for mechani- weight by a second chain. When either end of the release cal strength of the ? nal part, and another to create support chain is dropped, the buoyancy of the lander causes it to rise, structure as the part is being made, if required. The support while the negative weight of the anchor chain causes it to material must be removed from the ? nal part before it is put drop. The release chain continues to pull through the ring into use. The support material Polyvinyl Alcohol (PVA) is re- link that is attached to the anchor chain until it is free.

moved by water immersion. Dr. Bart Chadwick, then a scien- tist at the USN SPAWAR laboratory on Point Loma, suggested The Elegance of Simplicity

PVA ? lament might be used as a dissolvable release link. As entropy describes a gradual decline into disorder, Mur-

It’s been tried by some, I understand, though I have not heard phy’s Law de? nes a “seemingly spiteful behavior manifested how it worked. by inanimate objects” brought about by “malignity of matter,

Once the release element is chosen, adapting it to a lander the total depravity of inanimate things, whether the exciting 72 September/October 2022

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