I know I am not going to make any friends by saying this but it needs to be said.I would majorly hate to be a member of the generation that just can't stand to wait until it [whatever "it" may be] actually happens. I get the impression that they would never be able to stand the wait time of several YEARS while a probe makes its way to Jupiter, Saturn, Uranus, Neptune, Pluto or the Ort cloud. Their heads would explode. Try launching a probe like that knowing that you yourself may very well not live long enough to see it arrive and that children who are in 4th grade at launch date would likely be the scientists that would monitor and record the arrival. Do you have the patience for that?Jeepers people. The solar system isn't your back yard that can be crossed in a leap and a bound. SpaceX will provide photographs when it wants to and not one second before - they don't owe any of us a thing.Falcon Heavy will launch when it is ready. - Give it a rest and have a cup of tea or coffee or latte-mocha-chi-whatever.Chill. It will happen when it happens. THIS site will be the first to let you know it's happening so just stay tuned and quit complaining.
Quote from: vaporcobra on 12/30/2017 06:05 amYeah, judging from some coincidentally accurate porkchop plots and a few articles, Roadster can certainly make it to a rather close encounter with Mars, it just might take anywhere from a 12-24 month coast period to get there.What's with the asymptote in that porkchop plot? It seems like the required dV around Jan 15 is actually extremely sensitive to the exact date selected. Is that just an artifact of some other choice made in the plot, or is there an actual orbital mechanics reason why Jan 15 would be so much worse than Jan 1?
Yeah, judging from some coincidentally accurate porkchop plots and a few articles, Roadster can certainly make it to a rather close encounter with Mars, it just might take anywhere from a 12-24 month coast period to get there.
Quote from: cscott on 12/30/2017 01:30 pmQuote from: vaporcobra on 12/30/2017 06:05 amYeah, judging from some coincidentally accurate porkchop plots and a few articles, Roadster can certainly make it to a rather close encounter with Mars, it just might take anywhere from a 12-24 month coast period to get there.What's with the asymptote in that porkchop plot? It seems like the required dV around Jan 15 is actually extremely sensitive to the exact date selected. Is that just an artifact of some other choice made in the plot, or is there an actual orbital mechanics reason why Jan 15 would be so much worse than Jan 1?I found the answer to my own question:http://hopsblog-hop.blogspot.com/2013/01/deboning-porkchop-plot.htmlSo we're rapidly approaching the time period where an expensive 180 degree phase change is necessary to intercept Mars. Unless SpaceX is willing to wait until late February, they are going to have to do a mid-course burn to do the necessary inclination change to intercept Mars.This might have been a factor in SpaceX's desire to get the first FH launch off in December. Given that they don't seem like they're going to wait 50 days to launch it --- does that imply that the S2 can do a second inclination-change burn after a hundred days of loiter? Or is there some other clever way to intercept Mars (a transfer that doesn't take 180 degrees of anomaly, for instance)?
So we're rapidly approaching the time period where an expensive 180 degree phase change is necessary to intercept Mars.
Bah!I DID wait through the 9.5 year journey to Pluto (Having worked on the mission)One of my personal efforts has been in the works for twenty years, and it can't really yet be said to be a going concern.But I want MORE PROGRESS.I still remember the rapid progress of the "Space Race".FASTER!Fly that Heavy, already!There. I said it. Now back to waiting.
So FH spent less than a day at the pad doing fit checks.
Quote from: wannamoonbase on 12/29/2017 02:09 pmI think the probability of success is pretty high, but not as high as a F9 of course.I think 50-50 is about right. That's what Elon suggested, if I recall correctly.
I think the probability of success is pretty high, but not as high as a F9 of course.
The first Delta 4 Heavy failed...
Quote from: mme on 12/29/2017 04:15 pmQuote from: mn on 12/29/2017 03:43 pm...Thanks for explanation, but I'm still stumped by the 1 vs 3 core?Whatever torque issues are on one core they have obviously solved, so what happens when you have 3 cores side by side? as I said in my question: why is it a larger problem and not the same problem 3 times (with the same solution applied 3 times)?If you watch the the liftoff of the first Falcon 9, it clearly rotates. For a single stick, that's not really a big deal. But now bolt three of them together and rather than rotate freely in space they will be torquing the connections.The issue they are worried about is during ignition, not during flight.(and we've seen many launches since then, I don't think they have a problem here)
Quote from: mn on 12/29/2017 03:43 pm...Thanks for explanation, but I'm still stumped by the 1 vs 3 core?Whatever torque issues are on one core they have obviously solved, so what happens when you have 3 cores side by side? as I said in my question: why is it a larger problem and not the same problem 3 times (with the same solution applied 3 times)?If you watch the the liftoff of the first Falcon 9, it clearly rotates. For a single stick, that's not really a big deal. But now bolt three of them together and rather than rotate freely in space they will be torquing the connections.
...Thanks for explanation, but I'm still stumped by the 1 vs 3 core?Whatever torque issues are on one core they have obviously solved, so what happens when you have 3 cores side by side? as I said in my question: why is it a larger problem and not the same problem 3 times (with the same solution applied 3 times)?
The gimbal of the engines is fully capable of eliminating or inducing any roll wanted or unwanted.
I'm not concerned by any flight control guidance authority issues, just potential pneumatics and unlatch hangs at booster sep...
Due to thrust torque (a thrust-induced rotation)...I believe the torque mentioned is around a horizontal axis. A single stick might use an asymmetric engine ignition sequence without overstressing its own octaweb. But placed side by side, the asymmetric startup thrusts could overstress one or both webs. Now think of that happening on both sides of the center booster web simultaneously... complex.I thought the problem would actually be in any mismatch in the overall thrust startup of the two side boosters, which could result (say) in the links on one side of the center booster being lift-loaded before the other. Could cause a center tube or link failure, I would imagine. Fireball.
If they truly think that FH only has a 50% chance of succeeding, they are not going to launch. Period. They are going to want to be a lot more confident than that.
Quote from: Lars-J on 12/29/2017 05:10 pmIf they truly think that FH only has a 50% chance of succeeding, they are not going to launch. Period. They are going to want to be a lot more confident than that.I don't agree. I'm not sure it's possible to get more than 50% confident.Of course, SpaceX will have addressed 100% of the problems that they have thought of. But so has every other rocket maker, and historically about 50% of the first try of a new rocket have failed (see Rocketlab for the most recent example...).So Musk might well believe, that after addressing every problem they know about, there is still a 50% chance of failure. And there is nothing they can do about this, since they have already addressed every problem they could imagine. The only way to proceed is to launch and let nature have a go at seeing what SpaceX could not.
Quote from: FutureSpaceTourist on 12/20/2017 09:05 amLarger versionsIn the post (on the update thread) I'm referencing, the posted image of the 27-Merlin business end (FH-mated3.jpg) has four curious objects, a pair between each side booster and the main. A colleague on another forum speculated that they might be damping devices, and I speculate they might be actuators in the separation system. I've cropped a closeup from the cited photo and am attaching it as FH_Whazzat_0.jpg. Does anyone know what they are, or care to guess?
Larger versions
I see very little (if any) risk for POGO for FH, since they are flying the same stages as F9. Same engines, same tank lengths. POGO - if present - will show up in early launches. All this talk of possible failure points - one more dramatic than the next - starts to border on concern trolling, IMO. “Surely SpaceX has not thought of *this*?”
I love Elon's remark (about a year ago) that if Falcon Heavy just lifts off and clears the LC-39A launchpad, he'll consider the test a success. Certainly it would be a Bad Day for all involved to lose LC-39A.Has anyone done the math for at what point during flight, if the whole stack breaks up, will the ballistics carry the debris back down to earth CLEAR of the launch complex? (i.e. NOT do what Antares did to Wallops Pad 0 in Oct 2014) Obviously this moment would be after the pitchover starts.The simplest calc would be to just treat the whole stack as a point mass and then run that back down to ground -- i.e. just watch the instantaneous impact point (IIP) and wait for it to clear the fenceline, plus whatever distance is appropriate for the impact fireball. The harder calc would be assuming that the stack detonates, and now you've got a debris cloud that's raining down, including some that was propelled BACK to the west. So how much further would it need to be out for the propelled debris to also clear?My guess is it's around 30 seconds, give or take 10 seconds. That's the moment on the mission clock that I'll be watching for ...Sorry to be macabre. It's what engineers do, anticipate everything that can go wrong, right?
...My guess is it's around 30 seconds, give or take 10 seconds. That's the moment on the mission clock that I'll be watching for ...Sorry to be macabre. It's what engineers do, anticipate everything that can go wrong, right?
I don't agree. I'm not sure it's possible to get more than 50% confident.Of course, SpaceX will have addressed 100% of the problems that they have thought of. But so has every other rocket maker, and historically about 50% of the first try of a new rocket have failed (see Rocketlab for the most recent example...).So Musk might well believe, that after addressing every problem they know about, there is still a 50% chance of failure. And there is nothing they can do about this, since they have already addressed every problem they could imagine. The only way to proceed is to launch and let nature have a go at seeing what SpaceX could not.
Not sure about the timing but I'll be holding my breath until it clears away from the pad. Would hate to damage/destroy all that. For me that's about 10/15 seconds and anything after that should be over the ocean. Quote from: ChrisC on 12/31/2017 04:51 am...My guess is it's around 30 seconds, give or take 10 seconds. That's the moment on the mission clock that I'll be watching for ...Sorry to be macabre. It's what engineers do, anticipate everything that can go wrong, right?
If you look at this fabulous Falcon Heavy launch simulation vid by Zach and freeze it at the right time you should get an idea of when the stack wouldn't tumble back on the launch pad:Looks like around 15 seconds elapsed mission time to me.
My guess is it's around 30 seconds, give or take 10 seconds. That's the moment on the mission clock that I'll be watching for ...
If you look at this fabulous Falcon Heavy launch simulation vid by Zach and freeze it at the right time you should get an idea of when the stack wouldn't tumble back on the launch pad ... Looks like around 15 seconds elapsed mission time to me.
Quote from: ChrisC on 12/31/2017 04:51 amMy guess is it's around 30 seconds, give or take 10 seconds. That's the moment on the mission clock that I'll be watching for ...Quote from: Oersted on 12/31/2017 02:44 pmIf you look at this fabulous Falcon Heavy launch simulation vid by Zach and freeze it at the right time you should get an idea of when the stack wouldn't tumble back on the launch pad ... Looks like around 15 seconds elapsed mission time to me.Thanks Oersted for the link to that GREAT simulation.Zach, could you run that with a view from the side, showing the IIP during the first 30 seconds? (in other words, keep the ground in view, and we can use the stack height to estimate horizontal distance.Per the simulation, the pitchover doesn't even start until +15 seconds, so +15 secs is definitely NOT long enough (it will fall straight back down, a la Antares as I mentioned). By my guess, looking at downrange distance, altitude and apogee, it's not until about +25 seconds (+/- 5 secs) that the IIP would clear the LC-39A fenceline, 400 meters from the pad. We are converging on a solution