....SpaceX is taking alot of risks with this system. I think it will work, but its unnecessarily risky IMHO. I would not be surprised if SES9 failed in flight due to something related to the densified LOX, or a future flight for that matter. However, provided it succeeds it will build data parameters for the next flight, and so forth, so each flight afterwards on the new system builds confidence and rationale. Correct me if I am wrong but didn't OG2 use a FT Falcon 9? If so that provides a bit more confidence although I still think there are some substantial risks with this LV currently.
Correct me if I am wrong but didn't OG2 use a FT Falcon 9? If so that provides a bit more confidence although I still think there are some substantial risks with this LV currently.
Quote from: FinalFrontier on 03/01/2016 05:24 pm....SpaceX is taking alot of risks with this system. I think it will work, but its unnecessarily risky IMHO. I would not be surprised if SES9 failed in flight due to something related to the densified LOX, or a future flight for that matter. However, provided it succeeds it will build data parameters for the next flight, and so forth, so each flight afterwards on the new system builds confidence and rationale. Correct me if I am wrong but didn't OG2 use a FT Falcon 9? If so that provides a bit more confidence although I still think there are some substantial risks with this LV currently.It's a risky business, and we all have different levels of tolerance. Fortunately, the only opinions that matter about what level is 'unnecessary' are the customers, and they are responding accordingly (including negatively, see the recent ViaSat change). On the whole, enough folks are satisfied that this level of risk seems justifiable. And yes, Orbcomm-2 was FT.
Quote from: FinalFrontier link=topic=34 077.msg1498281#msg1498281 date=1456856652Correct me if I am wrong but didn't OG2 use a FT Falcon 9? If so that provides a bit more confidence although I still think there are some substantial risks with this LV currently. I don't think the risks are flight related. The issue comes down to how many attempts to launch are they going to have to go through to get off the ground.Like the Drake equation there is a long chain of variables that are multiplied together to produce the probability of getting a payload into the proper orbit. SpaceX has now added 2 more variables, RP1 and LOx temp to that string (4 if you break it into first and second stage).It's great they are trying and using this technology, perhaps they master it. But their ability to respond to big launch windows appears limited for this vehicle configuration.
Winds peaking at 70 m/s (157mph) at 10km (32,000 ft). Those speeds are seen in category 4 hurricanes on the surface but are more common higher up.
Why Friday? Is the wind shear forecast not to improve till then, or do the teams need more time to rest and chill down the fuel, etc.?
SpaceX SpaceX 8 minutes ago Launch updateUnfortunately upper-level winds continue to exceed acceptable limits and are expected to get worse as we approach tonight’s launch window, so we are forgoing today’s launch attempt. Winds are forecast to exceed acceptable limits through Thursday. Our team will continue working with the Air Force’s Launch Weather Officer to evaluate the best available opportunity for flight in the coming days.
Could someone address succinctly the issue of why (modern) guidance algorithms can't handle wind shear?It can't really be a structural issue, can it? Just keep the pointy end into the (local relative) wind!?
It's not the speed itself that's the problem, it's the rapid variation in speed vs. altitude. Uniform speed all around would just make the rocket drift a bit, which the guidance can compensate for. On the other hand, shear like this can cause a sudden torque on the vehicle. At high Q which is around those altitudes, that's a bad thing.
It can't really be a structural issue, can it? Just keep the pointy end into the (local relative) wind!?