Quote from: Lar on 12/16/2017 05:27 pmQuote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.Even though I thought you were too critical of my wording, thanks for the answer!
Quote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.
Have the strap-ons been mated to the core?
Quote from: clongton on 12/16/2017 06:27 pmQuote from: Lar on 12/16/2017 05:27 pmQuote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.The term in longest use in the industry is strap-on boosters. I remember this term from back in the 60's and 70's. But there are many variations and almost any of them are readily identifiable for what they are. At least they don't look like New Shepard.
Quote from: Lar on 12/16/2017 05:27 pmQuote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.The term in longest use in the industry is strap-on boosters. I remember this term from back in the 60's and 70's. But there are many variations and almost any of them are readily identifiable for what they are.
Quote from: shuttlefan on 12/16/2017 06:23 pmQuote from: Lar on 12/16/2017 05:27 pmQuote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.Even though I thought you were too critical of my wording, thanks for the answer! I wasn't CRITICAL, I was having some fun with it. As often is my wont, because I love words and word play...I'll elaborate a bit further, I now know for a fact the side boosters have been connected to the center core but that's all I can say. That really shouldn't be all that surprising given the calendar...
Quote from: clongton on 12/16/2017 06:27 pmQuote from: Lar on 12/16/2017 05:27 pmQuote from: shuttlefan on 12/16/2017 04:03 pmHave the strap-ons been mated to the core?I think the preferred term is side booster? Strap-ons? Mating? Might be a different forum you're thinking of?That said I think they have been but we haven't seen any public pics yet IIRC.The term in longest use in the industry is strap-on boosters. I remember this term from back in the 60's and 70's. But there are many variations and almost any of them are readily identifiable for what they are.It's been an AWFUL long time since some members of this forum have thought about anything except in terms of rockets, it appears.C'mon, guys -- humans are animals too, y'know...
It does get me thinking, though. Ideally, they'd want as much separation between the two side boosters as possible, to prevent any possible interactions. Flipping horizontally and firing up the three boostback engines mid-flip would push the boosters as far away from each other as possible; then they'd be following a trajectory such that their closest approach would be the landing burn itself.
Any set date yet for rollout to Pad A for fit checks, static fire, etc.?
I'd explain more as how this would apply to this and other potential missions, but it's the wrong thread for that apparently.Only for the Demo mission, not for FH specific items, or other missions.But, you should closely watch for how "horizontal staging" works on this Demo mission. SX has had problems with staging on other inaugural flights of new vehicles, especially Falcon 1, where they had issues for consecutive missions with recontact.Watch for booster engine cutoff, notice if the combined vehicle "twists" (there are multiple engines, they don't tail-off all the same) or "oscillates" - the boosters should be entirely passive before separation.One means that has worked well for SX separation events has been spring separation - constant force through distance (F=kX) rather than thrusters (or other) means a predictable trajectory that avoids contact (thrusters have variable impulse requiring different amounts of time to get the same cumulative force).Also, observe the roll of the core and stages, to see if residual torques from the spin-down of the turbopumps/gas generators.
Quote from: CuddlyRocket on 12/16/2017 03:31 pmQuote from: Jcc on 12/16/2017 01:51 pmI'm kind of curious about why one pad it black and the other white. If the black paint is radar reflective to make landings more precise, did they find radar reflective white paint, or integrate equivalent or better reflectivity in the concrete?Perhaps there's a difference in the radar reflectivity of the two pads to enable the individual boosters to distinguish between the two, thereby reducing the chances of one booster getting confused and both attempting to land at the same pad? I'm pretty sure radar is just for the altimeter.
Quote from: Jcc on 12/16/2017 01:51 pmI'm kind of curious about why one pad it black and the other white. If the black paint is radar reflective to make landings more precise, did they find radar reflective white paint, or integrate equivalent or better reflectivity in the concrete?Perhaps there's a difference in the radar reflectivity of the two pads to enable the individual boosters to distinguish between the two, thereby reducing the chances of one booster getting confused and both attempting to land at the same pad?
I'm kind of curious about why one pad it black and the other white. If the black paint is radar reflective to make landings more precise, did they find radar reflective white paint, or integrate equivalent or better reflectivity in the concrete?
... constant force through distance (F=kX) ...
Quote from: Space Ghost 1962 on 12/19/2017 12:18 am... constant force through distance (F=kX) ...Not constant force. Unless you claim SX uses non-linear springs.
If you looked at the inaugural launches for many vehicles, they had a slight roll rate (Falcon 1, 9, and most recently Electron) - that is because the estimated control to counteract the vehicle's movement (roll) wasn't sufficient.
Personally I would think they would leave the center engines running to fly the boosters away from the core, but we will see their choices soon enough.
Quote from: Comga on 12/19/2017 02:49 pmPersonally I would think they would leave the center engines running to fly the boosters away from the core, but we will see their choices soon enough. Keeping one engine burning seems reasonable. They can throttle one down to about 300 kN. The side booster masses at least 40,000 kg at that point (something like 27,000 at landing, plus boostback and re-entry burn fuel). So at most 7.5 m/s^2 acceleration for the side booster. Meanwhile the core has 9 engines x 845 kN = 7.6 MN. Mass is at most 600,000 kg (that would be a full center booster (450,000 kg) plus a massive second stage + payload (this was at 125.000 kg for Falcon 9)). So acceleration is at least 12.6 m/s and probably much more. So the center core is definitely pulling away from the side cores, even though they still have an engine running.However, if I had to pick an engine to keep running, I'd pick the one closest to the center core. This would add torque to point the side booster away from the core. From previous estimates, we can guess the moment of inertia of the core about the engines to be about 15,000,000 kg/m^2. 300,000 N applied 1.66 m from the center line is about 500,000 N-m of torque. This gives an angular acceleration of about 1/3 radian/s^2, or about 20 degrees in a second. At this point the engine is pushing the booster away from the core at a substantial fraction of a G, and under very positive control. The cold gas thrusters can help too.Using the center engine is also possible, but the separation would be slower. But maybe it's enough, and the center engine is already plumbed to run by itself. Only SpaceX knows for sure....