My first instinct when Elon said it was a failure to latch was "why would you want it to latch before landing?" I kind of expected that helium pressure in the rams would be such as to hold up the rocket but not so much as they'd lose all compliance. In other words, I expected them to be helium-pressurized shock-absorbing struts that would only latch after landing and all motion is stopped. Something about the design must not allow that, but a latch means the struts have no compliance other than elastic compliance which is a recipe for very high loads and easy mechanical failure during impact.
Quote from: Lee Jay on 01/18/2016 01:35 amMy first instinct when Elon said it was a failure to latch was "why would you want it to latch before landing?" I kind of expected that helium pressure in the rams would be such as to hold up the rocket but not so much as they'd lose all compliance. In other words, I expected them to be helium-pressurized shock-absorbing struts that would only latch after landing and all motion is stopped. Something about the design must not allow that, but a latch means the struts have no compliance other than elastic compliance which is a recipe for very high loads and easy mechanical failure during impact.Maybe the leg is latched at the pivot point, and the elasticity is in the combination of flexible leg and compressible strut.
After the last two efforts I'd think accuracy fades as a major concern. Damn.
Quote from: punder on 01/18/2016 01:40 amQuote from: Lee Jay on 01/18/2016 01:35 amMy first instinct when Elon said it was a failure to latch was "why would you want it to latch before landing?" I kind of expected that helium pressure in the rams would be such as to hold up the rocket but not so much as they'd lose all compliance. In other words, I expected them to be helium-pressurized shock-absorbing struts that would only latch after landing and all motion is stopped. Something about the design must not allow that, but a latch means the struts have no compliance other than elastic compliance which is a recipe for very high loads and easy mechanical failure during impact.Maybe the leg is latched at the pivot point, and the elasticity is in the combination of flexible leg and compressible strut.I can't imagine that a moment-bearing latch at the pivot point would do anything on a strut this long. No way you could take the load that way.
Quote from: Lee Jay on 01/18/2016 01:42 amQuote from: punder on 01/18/2016 01:40 amQuote from: Lee Jay on 01/18/2016 01:35 amMy first instinct when Elon said it was a failure to latch was "why would you want it to latch before landing?" I kind of expected that helium pressure in the rams would be such as to hold up the rocket but not so much as they'd lose all compliance. In other words, I expected them to be helium-pressurized shock-absorbing struts that would only latch after landing and all motion is stopped. Something about the design must not allow that, but a latch means the struts have no compliance other than elastic compliance which is a recipe for very high loads and easy mechanical failure during impact.Maybe the leg is latched at the pivot point, and the elasticity is in the combination of flexible leg and compressible strut.I can't imagine that a moment-bearing latch at the pivot point would do anything on a strut this long. No way you could take the load that way.I'll have to steal that, IANAME... but 1. Something was supposed to latch, but didn't and 2. SpaceX obviously doesn't lack for ME expertise. So I guess it's a mystery.
Quote from: punder on 01/18/2016 01:46 amQuote from: Lee Jay on 01/18/2016 01:42 amQuote from: punder on 01/18/2016 01:40 amQuote from: Lee Jay on 01/18/2016 01:35 amMy first instinct when Elon said it was a failure to latch was "why would you want it to latch before landing?" I kind of expected that helium pressure in the rams would be such as to hold up the rocket but not so much as they'd lose all compliance. In other words, I expected them to be helium-pressurized shock-absorbing struts that would only latch after landing and all motion is stopped. Something about the design must not allow that, but a latch means the struts have no compliance other than elastic compliance which is a recipe for very high loads and easy mechanical failure during impact.Maybe the leg is latched at the pivot point, and the elasticity is in the combination of flexible leg and compressible strut.I can't imagine that a moment-bearing latch at the pivot point would do anything on a strut this long. No way you could take the load that way.I'll have to steal that, IANAME... but 1. Something was supposed to latch, but didn't and 2. SpaceX obviously doesn't lack for ME expertise. So I guess it's a mystery. EM tweeted earlier that the failed part was a steel collet. New to me, so quick Wiki read speaks to an internal collet being used to lock together two telescoping tubes.
Subsequent news that the leg did not lock. Does this mean that the sea-state did not in the end play a decisive role in the landing result? - Ed Kyle
Falcon lands on droneship, but the lockout collet doesn't latch on one the four legs, causing it to tip over post landing. Root cause may have been ice buildup due to condensation from heavy fog at liftoff.
While we're doing again what nerds do and nitpicking over minutia, someone look at that image again and tell me the sharply-defined region around the bottom half of the stage is "soot" (versus my assertion from the previous landing that it's ablative paint that has clearly done its job).
Video:https://www.instagram.com/p/BAqirNbwEc0/QuoteFalcon lands on droneship, but the lockout collet doesn't latch on one the four legs, causing it to tip over post landing. Root cause may have been ice buildup due to condensation from heavy fog at liftoff.
Got to engine shutdown. Crap.
