You also hit on the key reason such a mechanism was never used...the forces involved.
Think about it...BY DEFINITION, the bolt (retaining pin, whatever) MUST be EXTREMELY difficult to seperate/remove. If not, it wouldn't withstand the forces involved.
Of course, we have a situation where, at a precise moment in time, we want to "remove" the bolt...suddenly.
Catch-22. Bolt needs to withstand incredible forces without budging, but at time X, needs to be easily and quickly removable.
Simply put...the mechanism that could yank the bolt out would be bulky, expensive, difficult (if not impossible) to engineer and, as you said, prone to failure....making the "exploding bolt" idea an elegant solution in its simplicity.
As explained above...they don't actually explode, per se. They're not a "bomb" or whatever that you could use to "blow something up".
Nor are most of them "bolts" as we would think of them...as in, they're not (usually) threaded steel rods with hex heads. They're probably actually closer to what we'd think of as rivits.
Given the forces involved during various portions of ascent or descent, SOMETHING has to hold "parts" (2 stages, the hatch covering a chute, an external fuel tank, whatever) together quite securely...but that joint must "fail" at a preciesly determined time...and must do so immediately.
Soooooo, a small (read, very small) charge INSIDE the bolt fires to degrade the bolt's structure to such a point that it can, literally, no longer do its job....the job of holding two components together VERY tightly. The intended effect, of course, is an immediate and complete "failure" of the bolt...allowing the components to seperate.
So, essentially, you answered your own question:):
"we have these two parts that need to be held together really tightly and then released very quickly"
A nifty answer, really, to a rather unique problem imo....the sort of thing OLD NASA was very good at./bc
The use of "cyanide fishing" is limited to collection of reef specimens for sale in the aquarium trade.
Essentially, the collector carries what amounts to a small "box" of cyanide. Upon encountering a particularly attractive or desirable fish, he "pops" the box open, releasing a puff of cyanide around the fish. This stuns (to say the least) the fish, making it easy to capture.
MAC (The Marine Aquarium Council) and others estimate that roughly 50% of the fish caught in this manner do not survive the process, and are dead by the time they're removed from the water, or do not survive the shipment to the local fish store. Of those that do "survive" to be sold to reef keepers, some estimates suggest that fully 80% of them die within 1 year in captivity.
None of this even touches on the obvious damage done by "poofing" a few square meters of reef with a big cyanide cloud. While estimates of the damage done vary greatly, it's pretty certain that there aren't a whole lot of reef critters out there that enjoy the experience.
Most of us who keep reef tanks built and grown by our own blood, sweat, and tears abhor the practice, and purchase captive raised animals ONLY, specifically to try to reduce the profit involved in such collection practices.
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You also hit on the key reason such a mechanism was never used...the forces involved. Think about it...BY DEFINITION, the bolt (retaining pin, whatever) MUST be EXTREMELY difficult to seperate/remove. If not, it wouldn't withstand the forces involved. Of course, we have a situation where, at a precise moment in time, we want to "remove" the bolt...suddenly. Catch-22. Bolt needs to withstand incredible forces without budging, but at time X, needs to be easily and quickly removable. Simply put...the mechanism that could yank the bolt out would be bulky, expensive, difficult (if not impossible) to engineer and, as you said, prone to failure....making the "exploding bolt" idea an elegant solution in its simplicity.
An alternative to what? Exploding bolts? No :)
The current NASA Culture? Absolutely. :)
As explained above...they don't actually explode, per se. They're not a "bomb" or whatever that you could use to "blow something up".
:) :
/bc
Nor are most of them "bolts" as we would think of them...as in, they're not (usually) threaded steel rods with hex heads. They're probably actually closer to what we'd think of as rivits.
Given the forces involved during various portions of ascent or descent, SOMETHING has to hold "parts" (2 stages, the hatch covering a chute, an external fuel tank, whatever) together quite securely...but that joint must "fail" at a preciesly determined time...and must do so immediately.
Soooooo, a small (read, very small) charge INSIDE the bolt fires to degrade the bolt's structure to such a point that it can, literally, no longer do its job....the job of holding two components together VERY tightly. The intended effect, of course, is an immediate and complete "failure" of the bolt...allowing the components to seperate.
So, essentially, you answered your own question
"we have these two parts that need to be held together really tightly and then released very quickly"
A nifty answer, really, to a rather unique problem imo....the sort of thing OLD NASA was very good at.
The use of "cyanide fishing" is limited to collection of reef specimens for sale in the aquarium trade.
Essentially, the collector carries what amounts to a small "box" of cyanide. Upon encountering a particularly attractive or desirable fish, he "pops" the box open, releasing a puff of cyanide around the fish. This stuns (to say the least) the fish, making it easy to capture.
MAC (The Marine Aquarium Council) and others estimate that roughly 50% of the fish caught in this manner do not survive the process, and are dead by the time they're removed from the water, or do not survive the shipment to the local fish store. Of those that do "survive" to be sold to reef keepers, some estimates suggest that fully 80% of them die within 1 year in captivity.
None of this even touches on the obvious damage done by "poofing" a few square meters of reef with a big cyanide cloud. While estimates of the damage done vary greatly, it's pretty certain that there aren't a whole lot of reef critters out there that enjoy the experience.
Most of us who keep reef tanks built and grown by our own blood, sweat, and tears abhor the practice, and purchase captive raised animals ONLY, specifically to try to reduce the profit involved in such collection practices.
In short, Save a reef...Grow your own.