On April 16 2015 06:39 GreenHorizons wrote: lol I just mean planning for it to tip over once it's touches down/gets close. Maybe the obvious thing I'm missing is that there is no way it could handle falling over structurally. My rocket experience is limited to cheap hobby store ones, which obviously don't have this problem, so perhaps that's what I'm missing.
For instance making it land into a man made hole type thing for a landing pad. Meaning that as long as it made it in there it couldn't tip all the way over.
that's a neat idea. You could have it like a reverse of the shuttle launch gantry. Instead of the arms falling away as it launches, arms come in and grab it as it lands.
Why not just drill a whole through the layers of the Earth land the rocket in the hole, allow gravity to slow the rocket after it crosses the center of the earth several times, and then just collect the rocket when it is resting in the core of the earth.
EZPZ
so much easier than just creating a reuseable rocket to save millions of dollars per launch.
Air resistance for the slow down, not gravity. Gravity luckily does not slow down things on multiple passes, or we would all be having a lot of fun in the center of the sun. (Poetry by me)
Watching that video I'm more convinced the barge should be more crater/silo shaped. With some sort of extreme strength inflatable bumpers or something.
Dunno, they very nearly had it there. Also notice how the rocket doesn't come straight down, but kinda sideway, and then stops the sideways motion at the last second? A silo would make that a lot harder. Not to forget that a silo would concentrate all of the rocket engine heat into a rather small bucket of air that is hard to exchange heat out of, which is probably dangerous too.
And a crater is a really bad idea, because it means you can ONLY land in the middle, every other surface is not straight. And while they do have some accuracy with the landing (They appear to hit the barque very well), do you really want to make the target you have to hit even smaller? Same problem with the silo idea.
On April 17 2015 05:42 Simberto wrote: Dunno, they very nearly had it there. Also notice how the rocket doesn't come straight down, but kinda sideway, and then stops the sideways motion at the last second? A silo would make that a lot harder. Not to forget that a silo would concentrate all of the rocket engine heat into a rather small bucket of air that is hard to exchange heat out of, which is probably dangerous too.
And a crater is a really bad idea, because it means you can ONLY land in the middle, every other surface is not straight. And while they do have some accuracy with the landing (They appear to hit the barque very well), do you really want to make the target you have to hit even smaller? Same problem with the silo idea.
I don't think making it roughly the same size (rounder) with walls would make the target that much smaller. I take your point on non flat surfaces though. Like I said, I presume they thought about this a great deal more than I have, so I don't think I'm providing some novel idea, I'm just curious why it didn't happen. It seems there isn't a glaringly obvious reason that they have already explained, so presumably it comes down to the physics/dynamics of the landing. It does seem like trying to land a pencil vertically on a desk surface instead of trying to land in a pen holder on a desk though.
It's pretty cool, the reason they come in side-ways is because their re-entry trajectory is set up to miss the barge on purpose. So if there's an engine failure during an early stage of the landing procedure, the rocket won't obliterate the barge.
On April 17 2015 05:42 Simberto wrote: Dunno, they very nearly had it there. Also notice how the rocket doesn't come straight down, but kinda sideway, and then stops the sideways motion at the last second? A silo would make that a lot harder. Not to forget that a silo would concentrate all of the rocket engine heat into a rather small bucket of air that is hard to exchange heat out of, which is probably dangerous too.
And a crater is a really bad idea, because it means you can ONLY land in the middle, every other surface is not straight. And while they do have some accuracy with the landing (They appear to hit the barque very well), do you really want to make the target you have to hit even smaller? Same problem with the silo idea.
I don't think making it roughly the same size (rounder) with walls would make the target that much smaller. I take your point on non flat surfaces though. Like I said, I presume they thought about this a great deal more than I have, so I don't think I'm providing some novel idea, I'm just curious why it didn't happen. It seems there isn't a glaringly obvious reason that they have already explained, so presumably it comes down to the physics/dynamics of the landing. It does seem like trying to land a pencil vertically on a desk surface instead of trying to land in a pen holder on a desk though.
This is still the warm up act, they will be landing either at Vandenberg or Cape Canaveral in a few months time.
SpaceX have identified a faulty valve as the cause of the landing failure, so hopefully the next attempt will nail it.
I find the comments on that article exceedingly funny.
I wonder how high they think the chance is that a team of people, who on average have an iq that is probably at least 30 points higher than that of the average commenter, who have studied the thing in question for a long time, and whose job it is to do something, have not yet come up with the obvious solution to all of the problems they currently have that you just came up with after 10 minutes of reading a superficial article about that thematic.
Pretty much every response to that article has been prefaced by some form of "well those guys are geniuses so they must have thought about this, but I wonder why...?"
If people didn't ask interested questions this thread would be 30 pages of stealthblue copy-pasting to himself, but I'm glad you've found a way to feel superior.
"This just isn't a good approach. I've recovered a ton of vehicles and I'd have never chosen this way. All three could have already been recovered with a better thought out approach."
"Elon musk stop trying to do this on the cheap. 1) Enlarge the first stage for more bring-back fuel capacity. This will enable softer, more controlled landings. This mod will also enable re-use of the first stage after GTO missions. 2) At least one of those Merlin engines needs to be gimballed. 3) Install "puffer jets" (like those on the F35B) on the nose for attitude control. C'mon Elon, stop wasting boosters. These mods pay for themselves right away upon first re-use."
were the ones i was specifically talking about. Note the utter lack of "They probably have thought about that" and the very confident assertment of "I know how they should do it"
There is nothing wrong with asking "Why are they doing x and not y", but the reasonable assumption should always be that they have a reason for doing so, and not that you alone just cracked the whole problem in less than 10 minutes with your abundant genius.
COLORADO SPRINGS — SpaceX is thought to be focusing on static friction in an engine throttle valve as the prime suspect for the loss of the Falcon 9 first stage during the third attempt at recovering the booster.
SpaceX founder and chief technology officer Elon Musk tweeted that “excess lateral velocity caused it [the booster] to tip over post landing.” In a later tweet that was subsequently withdrawn, Musk then indicated that “the issue was stiction in the biprop throttle valve, resulting in control system phase lag.” In this statement, Musk was referring to “stiction” — or static friction — in the valve controlling the throttling of the engine. The friction appears to have momentarily slowed the response of the engine, causing the control system to command more of an extreme reaction from the propulsion system than was required. As a result, the control system entered a form of hysteresis, a condition in which the control response lags behind changes in the effect causing it.
Despite the failure of the latest attempt, SpaceX will be encouraged by the landing accuracy of the Falcon 9 and the bigger-picture success of its guidance, navigation and control (GNC) system in bringing the booster back to the drone ship. The GNC also worked as designed during the prior landing attempt in January, which ended in the destruction of the vehicle following a hard touchdown on the edge of the platform.
Other control system modifications also appear to have functioned according to plan. These include aerodynamic mesh fins that were added in place of gaseous nitrogen control thrusters that were tested to control the rotation that occurred on the first test flight in September 2013. Prototype versions of the steerable fins were tested for the first time in May 2014 on a flight of the Falcon 9 Reusable (F9R) experimental vehicle during a test that reached an altitude of 1,000 meters. SpaceX is developing a new F9R after the first one was destroyed in August last year during a test at the company’s rocket development facility in McGregor, Texas.
Heh, I love that you are still keeping this thread going. Are you also on the spacex /r? It's where I go for all my info, I'll try and be more present here maybe I can answer some questions.
EPT
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