Ralathon Posted January 18, 2016 Share Posted January 18, 2016 37 minutes ago, SomeGuy123 said: They keep having "random" failures with the landing hardware. Bad valves, running out of hydraulic fluid, leg locking failure. By comparison, think about how many things go right with their Merlin rocket and the dragon spacecraft? Thousands and thousands of systems working right the first try. I wonder if the cause is systemic - if this landing hardware was engineered a different way than the main rocket, or maybe they were trying to save kilograms to the point of making the solution unreliable? It could just be random chance, I suppose. Nah, they're just in the first part of the bathtub curve. We know how to build rockets that go into space. We aren't too sure how to build rockets that come back. Expect to see a few years of ever decreasing failure rates as they figure out the weak spots. Link to comment Share on other sites More sharing options...
softweir Posted January 18, 2016 Share Posted January 18, 2016 10 hours ago, AngelLestat said: Damm, they was real close, perfect landing perfect accuracy.. Is incredible how they are improving.. I imagine they will make corrections to prevent this problem in the future. The SWATH design sounds good, but it said that it has many drawbacks which directly impact in the cost. They need a barge cheap to operate, or their profits by re usability decrease. Not sure how big are the gyroscopes in the barge.. But a really big gyroscope should not have any problem The gyro would have to deal with hundreds of tonne.metres of torque to stabilise a barge against wave action. That just isn't on the cards - it would need to be too big, too heavy, and way, way to expensive! In all probability, by the time it was big enough to be useful, it would be big enough to sink the barge. A much better idea would be to have deployable, deep-level stabiliser surfaces. The further you look beneath the waves, the less the waves move the water. Even a couple of hundred feet down submarines notice almost no wave action except in the heaviest of seas - further down, they experience none. Have a horizontal surface attached to the barge deep down and when the barge starts to move up it has to drag that surface through the less active water. This would reduce the amount of pitching. If it is made deployable - ie it can be lifted out of the water when not needed - then it won't increase the draught of the barge which would be a nuisance when docking it, and it won't increase drag when trying to tow the barge either! Another system used is active: a load of thrusters (propellers) are added to a vessel such that they can thrust up or down. As the wave starts to lift one corner of the barge, the relevant thruster thrusts down, dragging that corner down against the wave action. This doesn't really work well with flat-bottomed craft like the barge, but for a purpose-built, round-bottomed craft it can work very well. Link to comment Share on other sites More sharing options...
Rdivine Posted January 18, 2016 Share Posted January 18, 2016 Would they attempt to land the first stage again for SES-9 launch? Link to comment Share on other sites More sharing options...
magnemoe Posted January 18, 2016 Share Posted January 18, 2016 34 minutes ago, tater said: If you know actually something about a subject, and then read or hear an article done by reporters, you will pretty much always think the reporter is an idiot and doesn't know what they are talking about (because they don't). You will then read the next article about something you don't know that much about, and you'll believe it. This, most reporters are not specialists in the field they report on and tend to have short deadlines, media also want exiting stuff, drama and catastrophes. Computers and IT was pure humor until they got specialists. Link to comment Share on other sites More sharing options...
tater Posted January 18, 2016 Share Posted January 18, 2016 5 minutes ago, magnemoe said: This, most reporters are not specialists in the field they report on and tend to have short deadlines, media also want exiting stuff, drama and catastrophes. Computers and IT was pure humor until they got specialists. Yeah, it's very hit or miss. Anyone who was a journalism major basically has no knowledge about anything that they don't already know about, and no expert knowledge they don't have already. Any science/engineering reporters not trained as scientists or engineers are pretty clueless in my experience. My wife says the same about medical/bio stories. Link to comment Share on other sites More sharing options...
AngelLestat Posted January 18, 2016 Share Posted January 18, 2016 21 minutes ago, softweir said: The gyro would have to deal with hundreds of tonne.metres of torque to stabilise a barge against wave action. That just isn't on the cards - it would need to be too big, too heavy, and way, way to expensive! In all probability, by the time it was big enough to be useful, it would be big enough to sink the barge. A much better idea would be to have deployable, deep-level stabiliser surfaces. The further you look beneath the waves, the less the waves move the water. Even a couple of hundred feet down submarines notice almost no wave action except in the heaviest of seas - further down, they experience none. Have a horizontal surface attached to the barge deep down and when the barge starts to move up it has to drag that surface through the less active water. This would reduce the amount of pitching. If it is made deployable - ie it can be lifted out of the water when not needed - then it won't increase the draught of the barge which would be a nuisance when docking it, and it won't increase drag when trying to tow the barge either! Another system used is active: a load of thrusters (propellers) are added to a vessel such that they can thrust up or down. As the wave starts to lift one corner of the barge, the relevant thruster thrusts down, dragging that corner down against the wave action. This doesn't really work well with flat-bottomed craft like the barge, but for a purpose-built, round-bottomed craft it can work very well. Gyros are much stronger of what you believe by some grades of magnitud.https://www.youtube.com/watch?v=mBVztfLN3lk If you used them in a ship, the ship will only be moved half up, and half down (keeping its horizontal angle) by each wave. Other methods as deep level stabiliser surfaces may work, Still i am not in position to said what method would be better for stability. But any counter thrust method should be hard to do, it would be difficult to predict the movement pattern to counter, propellers take some time to generate thrust, and you need them not just in the landing moment, also all the way back generating a lot of drag. Link to comment Share on other sites More sharing options...
Lukaszenko Posted January 18, 2016 Share Posted January 18, 2016 Gyros, thrusters, a bigger, more stable ship might all work or not, but they would be solving a problem that apparently, judging from the video, doesn't exist. Link to comment Share on other sites More sharing options...
Wjolcz Posted January 18, 2016 Share Posted January 18, 2016 So they actually nailed it, but the landing leg didn't lock properly. Could that be caused by some atmospheric/flight event or did they just got unlucky? Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted January 18, 2016 Share Posted January 18, 2016 2 minutes ago, Veeltch said: So they actually nailed it, but the landing leg didn't lock properly. Could that be caused by some atmospheric/flight event or did they just got unlucky? According to the original tweet, they're suspecting ice buildup from the fog ATM. To me, it's sounding like perhaps a case of an unforeseen combination of conditions leading to an otherwise "dumb" failure. Landing a rocket is still so new, maybe no one ever considered the effects of sitting in fog full of cryogenic oxygen. Link to comment Share on other sites More sharing options...
ChrisDayVACCO Posted January 18, 2016 Share Posted January 18, 2016 On 1/16/2016 at 8:35 PM, fredinno said: I think you might have to hold a propulsion module seperately, in another cubesat bay. Only problem is that would increase the complexity enormously. I think soon 12U Cubesats will become built and used, for longer distance applications. You are right about the 12U CubeSats becoming more common in the future. You can already buy a 12U CubeSat launcher: http://www.planetarysystemscorp.com/ That size would increase the scientific payload mass on a CubeSat tremendously! Link to comment Share on other sites More sharing options...
AngelLestat Posted January 18, 2016 Share Posted January 18, 2016 (edited) 1 hour ago, Lukaszenko said: Gyros, thrusters, a bigger, more stable ship might all work or not, but they would be solving a problem that apparently, judging from the video, doesn't exist. You really think that a constant change of 10 degree in your landing pad is fine?https://youtu.be/ivdKRJzl6y0?t=29m40s Edited January 18, 2016 by AngelLestat Link to comment Share on other sites More sharing options...
Albert VDS Posted January 18, 2016 Share Posted January 18, 2016 4 hours ago, Nibb31 said: I was talking about the second landing attempt (CRS-6), which was a bit of a hard landing, where the rocket also tipped over. The hard landing was the reason of the failure, but a sturdier design for the landing legs might have saved the rocket. It doesn't need to be sturdier if it lands vertical all legs bare the same weight. The legs need to be more reliable. Sturdier means heavier, and that's not what a rocket needs. Link to comment Share on other sites More sharing options...
Motokid600 Posted January 18, 2016 Share Posted January 18, 2016 Trust me when I say that if a bunch of people on a video game forum thought of it... SpaceX has too. Link to comment Share on other sites More sharing options...
softweir Posted January 18, 2016 Share Posted January 18, 2016 2 hours ago, AngelLestat said: Gyros are much stronger of what you believe by some grades of magnitud.https://www.youtube.com/watch?v=mBVztfLN3lk If you used them in a ship, the ship will only be moved half up, and half down (keeping its horizontal angle) by each wave. Other methods as deep level stabiliser surfaces may work, Still i am not in position to said what method would be better for stability. But any counter thrust method should be hard to do, it would be difficult to predict the movement pattern to counter, propellers take some time to generate thrust, and you need them not just in the landing moment, also all the way back generating a lot of drag. Cool vid! However. Balancing a motorbike in that way is a dozen orders of magnitude a smaller problem than that of keeping a ship level when acted on by waves. That one is "easy" (it's not) doesn't make the other possible. Link to comment Share on other sites More sharing options...
fredinno Posted January 18, 2016 Share Posted January 18, 2016 57 minutes ago, Albert VDS said: It doesn't need to be sturdier if it lands vertical all legs bare the same weight. The legs need to be more reliable. Sturdier means heavier, and that's not what a rocket needs. Considering they've made the rocket bigger twice already for reusability, I don't think the sturdier legs would add much to it. Link to comment Share on other sites More sharing options...
Albert VDS Posted January 18, 2016 Share Posted January 18, 2016 But "not much" is a whole lot for a rocket. It's a reason why the external tank of the Space Shuttle wasn't painted. Link to comment Share on other sites More sharing options...
Kartoffelkuchen Posted January 18, 2016 Share Posted January 18, 2016 37 minutes ago, fredinno said: Considering they've made the rocket bigger twice already for reusability, I don't think the sturdier legs would add much to it. Well, but they've only made the rocket bigger, so to say, in order to squeeze out as much performance out of it as possbile, to be able to do also recovery on GTO missions. If you now start to make the legs heavier again, we can just go back to 1.1 again. And they've proven that it works for the landing part, and also they redesigned or improved the legs on F9 FT (we should start calling the Full Thrust Version simply Falcon 9 onwards from the next mission, since there's no other Falcon 9 variant active by then), by how much and what they chaged, no idea. But maybe they'll just grab the legs again and work a bit on that locking mechanism to make it more reliable for upcoming missions. I mean, basically every Falcon 9 they launch had its own small, unique adjustments. Link to comment Share on other sites More sharing options...
tater Posted January 18, 2016 Share Posted January 18, 2016 Sturdy doesn't seem to be the issue in this case, it was a failure to lock. They presumably have some shock absorption as well. Link to comment Share on other sites More sharing options...
Airlock Posted January 18, 2016 Share Posted January 18, 2016 Here's a side-by-side comparison of each barge landing so far. Link to comment Share on other sites More sharing options...
wumpus Posted January 18, 2016 Share Posted January 18, 2016 22 minutes ago, Airlock said: Here's a side-by-side comparison of each barge landing so far. I still think they need to ditch the barge (or at least stabilize it), but that looks exactly like the failure description: landed, and then fell over on the failed leg. Of course, I wonder how well they can test that "weld the legs on" bit in rough weather. Link to comment Share on other sites More sharing options...
Albert VDS Posted January 18, 2016 Share Posted January 18, 2016 19 minutes ago, wumpus said: I still think they need to ditch the barge (or at least stabilize it), but that looks exactly like the failure description: landed, and then fell over on the failed leg. Of course, I wonder how well they can test that "weld the legs on" bit in rough weather. The barge is already extremely stable even in storm conditions. It didn't tip over because of the barge, but because of the leg. A land landing would have had the same result. Link to comment Share on other sites More sharing options...
codepoet Posted January 18, 2016 Share Posted January 18, 2016 Sounds like a silly argument about strengthening the legs. It seems that on this recent landing (jason3) the leg did not break, but failed to operate correctly. Now it occurs to me that the really interesting question is - did the leg fail to operate correctly because it was somehow damaged due to the effects of reentry? That would be an issue for SpaceX. They know that the legs can work from the grasshopper tests (or whatever grasshopperv2 was called) However those tests did not simulate the effects of reentry on the legs. We also know that is is possible for the legs to survive reentry because on the last two flights 7 out of 8 of the legs operated correctly following reentry, However perhaps they need to adjust the design to mitigate a reentry effect that has so far caused a 12% failure rate. This is a specific example of the whole "what is the point of inspection of the recovered stage?" debate. They will want to inspect the recovered stages to see where components are affected by flight and reentry in particular that will result in a elevated probability of a component failure, even if that failure has not yet occurred and cause the loss of a stage. By adjusting the design to reduce the chance of failure they make the vehicle more reliable. It is way more subtle than just "fire it up again, does it work?" Link to comment Share on other sites More sharing options...
Albert VDS Posted January 18, 2016 Share Posted January 18, 2016 9 minutes ago, codepoet said: Now it occurs to me that the really interesting question is - did the leg fail to operate correctly because it was somehow damaged due to the effects of reentry? Elon Musk on Instragram: Falcon lands on droneship, but the lockout collet doesn't latch on one the four legs, causing it to tip over post landing. Root cause may have been ice buildup due to condensation from heavy fog at liftoff. Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted January 18, 2016 Share Posted January 18, 2016 5 minutes ago, Albert VDS said:Elon Musk on Instragram: Falcon lands on droneship, but the lockout collet doesn't latch on one the four legs, causing it to tip over post landing. Root cause may have been ice buildup due to condensation from heavy fog at liftoff. See, now this does not sound like any sort of inherent design flaw or mechanical defect, just operating outside of designed conditions. Rocket launches in fog are pretty rare. Landing a rocket that was launched in the fog, this would be the first. Modifying weather constrains and/or adding a deicing system should be fairly simple. Link to comment Share on other sites More sharing options...
Motokid600 Posted January 18, 2016 Share Posted January 18, 2016 Maybe just some heaters around the latch. Link to comment Share on other sites More sharing options...
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