Quote from: V42 on 07/24/2021 05:03 pmQuote from: meekGee on 07/24/2021 04:27 pmQuote from: V42 on 07/24/2021 04:08 pmQuote from: grndkntrl on 07/24/2021 01:53 pmQuote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.All this talk (here and elsewhere) about the section 9 configuration ignores one thing… most proposed arrangements do not form a stable geometry for the lift when stacking. No matter how you close out the currently missing fourth corner, the assembly will sag without horizontal members joining the bottom of the corner columns together. But there is also no provision in the corner column gusset plates to attach them in that area. So unless the lifting fixture can provide the needed stiffness, either some kind of temporary bracing will need to be added or there is more to come to section 9 than has been proposed so far.You can complete the missing diagonals wIth cables, right? Maybe will need to tension them on final assembly but that's just another come-along.Unfortunately cables don’t work well in compression . But I was mistaken and those temporary horizontal members are indeed there. So my apologies for not looking more careful and raising a nonissue.Oh come on, you use two, look at any cable stabilized structure out there...
Quote from: meekGee on 07/24/2021 04:27 pmQuote from: V42 on 07/24/2021 04:08 pmQuote from: grndkntrl on 07/24/2021 01:53 pmQuote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.All this talk (here and elsewhere) about the section 9 configuration ignores one thing… most proposed arrangements do not form a stable geometry for the lift when stacking. No matter how you close out the currently missing fourth corner, the assembly will sag without horizontal members joining the bottom of the corner columns together. But there is also no provision in the corner column gusset plates to attach them in that area. So unless the lifting fixture can provide the needed stiffness, either some kind of temporary bracing will need to be added or there is more to come to section 9 than has been proposed so far.You can complete the missing diagonals wIth cables, right? Maybe will need to tension them on final assembly but that's just another come-along.Unfortunately cables don’t work well in compression . But I was mistaken and those temporary horizontal members are indeed there. So my apologies for not looking more careful and raising a nonissue.
Quote from: V42 on 07/24/2021 04:08 pmQuote from: grndkntrl on 07/24/2021 01:53 pmQuote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.All this talk (here and elsewhere) about the section 9 configuration ignores one thing… most proposed arrangements do not form a stable geometry for the lift when stacking. No matter how you close out the currently missing fourth corner, the assembly will sag without horizontal members joining the bottom of the corner columns together. But there is also no provision in the corner column gusset plates to attach them in that area. So unless the lifting fixture can provide the needed stiffness, either some kind of temporary bracing will need to be added or there is more to come to section 9 than has been proposed so far.You can complete the missing diagonals wIth cables, right? Maybe will need to tension them on final assembly but that's just another come-along.
Quote from: grndkntrl on 07/24/2021 01:53 pmQuote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.All this talk (here and elsewhere) about the section 9 configuration ignores one thing… most proposed arrangements do not form a stable geometry for the lift when stacking. No matter how you close out the currently missing fourth corner, the assembly will sag without horizontal members joining the bottom of the corner columns together. But there is also no provision in the corner column gusset plates to attach them in that area. So unless the lifting fixture can provide the needed stiffness, either some kind of temporary bracing will need to be added or there is more to come to section 9 than has been proposed so far.
Quote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.
It looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.
Quote from: meekGee on 07/24/2021 06:10 pmQuote from: V42 on 07/24/2021 05:03 pmQuote from: meekGee on 07/24/2021 04:27 pmQuote from: V42 on 07/24/2021 04:08 pmQuote from: grndkntrl on 07/24/2021 01:53 pmQuote from: jfallen on 07/24/2021 01:18 pmIt looks like most of the speculation was wrong irt direct assembly. From Mary's photo they are using another jig. The final level looks like it will only have three columns, with the gap at the built up area from the previous level.No there are four columns, it's just the the 4th one is a little stubby one (see here) that will probably sit on top of the pulley block which is to be fitted on the taller column at overhang corner of section 8.They'll either:- attach this directly on top of that pulley block and then lift that two part assembly up to the aforementioned taller column on section 8 for installation. the rest of section 9 can then be lifted up and everything gets joined together; or, - install the stubby column to where it belongs on section 9 while it's on the jig at ground level, the stubby corner will be held in place to the two adjacent corner columns by the 2 horizontal connecting beams, not attached to the jig because it'll be "floating" above that corner of the jig with free air between. Then that gets lifted and joined to section 8.All this talk (here and elsewhere) about the section 9 configuration ignores one thing… most proposed arrangements do not form a stable geometry for the lift when stacking. No matter how you close out the currently missing fourth corner, the assembly will sag without horizontal members joining the bottom of the corner columns together. But there is also no provision in the corner column gusset plates to attach them in that area. So unless the lifting fixture can provide the needed stiffness, either some kind of temporary bracing will need to be added or there is more to come to section 9 than has been proposed so far.You can complete the missing diagonals wIth cables, right? Maybe will need to tension them on final assembly but that's just another come-along.Unfortunately cables don’t work well in compression . But I was mistaken and those temporary horizontal members are indeed there. So my apologies for not looking more careful and raising a nonissue.Oh come on, you use two, look at any cable stabilized structure out there...You do understand the concept of preload, right? Of course you can “push” on a preloaded cable as long as you don’t exceed whatever initial tension was in that cable. But a cable has to pull against something in order to preload it in the first place.If you’re thinking of a simple tower stabilizing guy-wire system, you need at least two for a 2-D planar system and three for a 3-D system.In a more general sense, you need as many degrees of constraint as rigid body degrees of freedom you are trying to restrain. A non-preloaded cable provides only 1/2 degree of freedom of constraint while a preloaded cable provides a full 1 degree of freedom of constraint.
Quote from: V42 on 07/24/2021 06:50 pmYou do understand the concept of preload, right? Of course you can “push” on a preloaded cable as long as you don’t exceed whatever initial tension was in that cable. But a cable has to pull against something in order to preload it in the first place.If you’re thinking of a simple tower stabilizing guy-wire system, you need at least two for a 2-D planar system and three for a 3-D system.In a more general sense, you need as many degrees of constraint as rigid body degrees of freedom you are trying to restrain. A non-preloaded cable provides only 1/2 degree of freedom of constraint while a preloaded cable provides a full 1 degree of freedom of constraint.It's not hard.If you have a rectangular frame, you can stabilize it with a single diagonal, if the diagonal can take compression without buckling.Alternatively, two tension-only diagonals (e.g. cables) will also do.
You do understand the concept of preload, right? Of course you can “push” on a preloaded cable as long as you don’t exceed whatever initial tension was in that cable. But a cable has to pull against something in order to preload it in the first place.If you’re thinking of a simple tower stabilizing guy-wire system, you need at least two for a 2-D planar system and three for a 3-D system.In a more general sense, you need as many degrees of constraint as rigid body degrees of freedom you are trying to restrain. A non-preloaded cable provides only 1/2 degree of freedom of constraint while a preloaded cable provides a full 1 degree of freedom of constraint.
https://twitter.com/NicAnsuini/status/1419051813043638272
The drawworks and cable spooler/drum around the adjacent corner of the tower's base says otherwise.
It's fixed in place and quite short so this can't be used as a crane. Instead it seems likely that a set of cables will pass through the nose and connect to a section below that slides on rails at variable height.
Are there any other examples of a tower with a vertically sliding carriage like SpaceX appears to be building?I can't think of any launch tower arm that was not firmly fixed to the tower itself.This adds a lot of complexity and the only good reason to go for sliding arms is in order to dampen the shock of a booster being caught.
.You could also compare it to the basic principle of the lifting mechanism on a forklift truck and/or stackers.There are lots of reasons why they went with the multipurpose arms on a carriage approach, all of which have been discussed here extensively.It's actually not really that complex at all when you really think about it.
Swing-jig crane? Pivot at the 'back' corner, extends over the shortened 'front' corner near the launch table. The corner doesn't point directly at the launch table (rotated slightly counter-clockwise) so the jib only needs a relative small angle of swing to be able to move from directly above the launch table to sufficiently far off to clear the legs. Roll SPMT next to launch table, swing jib over, lift vehicle, swing jib over table, lower vehicle. Simple, and unlike the grabber-arms it's a practically off-the-shelf system, which means it can be implemented fast.
It's still not clear to me how they're going to stack StarShip without a movable crane at the top of the tower.They need to lift it 100 meters into the air and then integrate it with the separation mechanism on the booster. How would you do this with movable arms? The starship so far has only been moved by hooking the nose. Are they going to add new lifting points around the "waist" of the vehicle? The wing surfaces don't look anywhere strong enough to hold the whole vehicle.
It would make sense for integration between the booster and starship to be performed on a platform that can hold workers and also fueling connections. Does this mean the tower will have two movable carriages?
It's also much easier to design arms that only need to close around a single axis going through the center of the launch table. I saw a render with arms that can both close and rotate but that seems very complicated.
The most likely solution at this point seems to be to keep the FrankenCrane around and use that for all lifts that require horizontal movement.
Crawler Crane to support SpaceX orbital launch site construction and launch operations. Note: 450ft structure height is when the crane is at its highest boom angle and will most frequently be at a height of 350ft.
Crawler Crane to be unsed in the construction of new SpaceX launch tower.