Elthy Posted March 8, 2016 Share Posted March 8, 2016 There should be less gravity losses, but the TWR gets so damn high its propably hard to controll. Link to comment Share on other sites More sharing options...
sgt_flyer Posted March 8, 2016 Share Posted March 8, 2016 nasaspaceflight forum has some high resolution images of the OCISLY barge back into the port - with the stage's debris on it. (when can even see 1 grid fin on one image) http://forum.nasaspaceflight.com/index.php?topic=36326.6300 Link to comment Share on other sites More sharing options...
fredinno Posted March 8, 2016 Share Posted March 8, 2016 3 hours ago, sgt_flyer said: looks like Falcon Heavy delays are beginning to impact spaceX customers... http://spacenews.com/inmarsat-worried-about-spacex-falcon-heavy-delays-books-reservation-for-ils-proton-launch/ Thus the greatest weakness of SpaceX rears its ugly head. Link to comment Share on other sites More sharing options...
sojourner Posted March 9, 2016 Share Posted March 9, 2016 It's the great weakness of the entire space industry - schedule slip. Link to comment Share on other sites More sharing options...
fredinno Posted March 9, 2016 Share Posted March 9, 2016 17 minutes ago, sojourner said: It's the great weakness of the entire space industry - schedule slip. SpaceX is the most prone to it, by far, which makes it its greatest weakness. Link to comment Share on other sites More sharing options...
sevenperforce Posted March 9, 2016 Share Posted March 9, 2016 On 3/6/2016 at 2:48 PM, KAL 9000 said: Wait, what? You have to get it (no pressure). It's the most realistic spaceflight simulator I've ever seen, and you get to blow stuff up! What's not to like? Finally got a chance to try out the demo today. Love it. Stiff learning curve...didn't kill any Kerbals yet, though. At least not outside the tutorials. Link to comment Share on other sites More sharing options...
sgt_flyer Posted March 9, 2016 Share Posted March 9, 2016 (edited) ouch, that definitely left a mark this time. Edited March 9, 2016 by sgt_flyer Link to comment Share on other sites More sharing options...
KerbonautInTraining Posted March 9, 2016 Share Posted March 9, 2016 Can't wait to see the footage. Let's just hope they haven't released it by choice, not because it got destroyed. Link to comment Share on other sites More sharing options...
Motokid600 Posted March 9, 2016 Share Posted March 9, 2016 11 hours ago, sevenperforce said: What are the differences between using a short three-engine suicide burn and a longer one-engine suicide burn? It's the same total dV, right? Same Dv, but with the one engine burn you get to use the rocket gimbals to adjust the trajectory for a longer period of time. Where as a three engine, shorter burn only gets to use the gimbals for a shorter period of time. Which probably is what contributed to this landing being a failure. MUCH less time to adjust the trajectory. Link to comment Share on other sites More sharing options...
KerbonautInTraining Posted March 9, 2016 Share Posted March 9, 2016 Just now, Motokid600 said: Same Dv, but with the one engine burn you get to use the rocket gimbals to adjust the trajectory for a longer period of time. Where as a three engine, shorter burn only gets to use the gimbals for a shorter period of time. Which probably is what contributed to this landing being a failure. MUCH less time to adjust the trajectory. I'm pretty sure the throttle played a bigger role in the fate of this landing. Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted March 9, 2016 Share Posted March 9, 2016 1 hour ago, sgt_flyer said: ouch, that definitely left a mark this time. Wow. Did not notice that gaping hole in the deck at first. I'm amazed there's as much left as there is. Link to comment Share on other sites More sharing options...
Mitchz95 Posted March 9, 2016 Share Posted March 9, 2016 Well, it should be pretty easy to figure out who won the bet on where it would land. Link to comment Share on other sites More sharing options...
Hannu2 Posted March 9, 2016 Share Posted March 9, 2016 If they knew that success was nearly impossible why did they try to hit to that barge and damage it? Why not some less valuable target? Link to comment Share on other sites More sharing options...
Streetwind Posted March 9, 2016 Share Posted March 9, 2016 (edited) 1 hour ago, Hannu2 said: If they knew that success was nearly impossible why did they try to hit to that barge and damage it? Why not some less valuable target? Like what? The open sea? They already did that many times. They need better data now, and the best way to obtain it is to try landing until it works. The barge deck is also not as expensive as you think it is - it's just a sheet of steel with some paint. I'd wager that last year, when a storm damaged the generator and maneuvering thruster housings, the barge repairs were more expensive than they are going to be this time around. Edited March 9, 2016 by Streetwind Link to comment Share on other sites More sharing options...
Hannu2 Posted March 9, 2016 Share Posted March 9, 2016 I thought some low value vessel. For example old barge from scrapping yard. Or maybe exactly defined place 50 m away from barge so that they could have used all navigation and investigation equipment. But probably you are right and repair costs and risks of expensive damage to the electronic equipment was lower than costs and risks of changing things would have been. Link to comment Share on other sites More sharing options...
kujuman Posted March 9, 2016 Share Posted March 9, 2016 also, with another target, if you do manage to stick the landing, the rest of the logistics become complicated. Might as well use what you think should work (I also imagine the barges get incremental upgrades as they collect data from landing attempts) Link to comment Share on other sites More sharing options...
kerbiloid Posted March 9, 2016 Share Posted March 9, 2016 Probably, they just didn't expect that badabum would be such great. As this flight had been presumed to be very fuel-expensive, they knew that there is not enough fuel to slowly land using one engine, as usual. But there remained a hope that a fast braking using three engines at once would take less fuel and maybe even bring a success. In the worst case — just one more broken rocket. But as T/W was too great, maybe they missed the correct short moment, and the disassembly was a little bit more rapid than before. (Also, now Falcon is the first space anti-ship missile). Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted March 9, 2016 Share Posted March 9, 2016 5 hours ago, kerbiloid said: (Also, now Falcon is the first space anti-ship missile). well, supposedly the Chinese already have one that's meant to be used against carriers... wonder where they got their guidance system... Link to comment Share on other sites More sharing options...
wumpus Posted March 9, 2016 Share Posted March 9, 2016 5 hours ago, kujuman said: also, with another target, if you do manage to stick the landing, the rest of the logistics become complicated. Might as well use what you think should work (I also imagine the barges get incremental upgrades as they collect data from landing attempts) One thing they would get from this attempt (without damaging the barge) is the effects of using 3 engines. I'm guessing this would have something like a TWR >6 (one engine at 60% throttle is still greater than 1). This might be useful as a pre-landing-burn before starting the "proper" suicide burn (or simply have the burn end such that the center engine could adjust the throttle as needed depending on how much delta-v the other engines provided). No idea how much fuel reserves you would need to make sure both engines would last through such a "preburn", but you would at least avoid a certain amount of gravity losses. Initially, I thought that a 6g+ burn might put a significant strain on the rocket (and it probably does), but the whole thing can handle rocket+fuel at >1g, so 10% of that mass at 6g+ isn't going to be nearly as hard (on the main structure. Some parts are going to feel all of it. That's certainly one of the reasons why they needed to at least try a recovery). Link to comment Share on other sites More sharing options...
KerbonautInTraining Posted March 9, 2016 Share Posted March 9, 2016 3 minutes ago, wumpus said: This might be useful as a pre-landing-burn before starting the "proper" suicide burn That's exactly what the entry burn is. It slows the stage with 3 engines to keep the atmosphere from ripping it apart. Link to comment Share on other sites More sharing options...
codepoet Posted March 9, 2016 Share Posted March 9, 2016 (edited) 5 hours ago, KerbonautInTraining said: That's exactly what the entry burn is. It slows the stage with 3 engines to keep the atmosphere from ripping it apart. So I have always wondered about this - does the re-entry burn occur to slow the rocket down before it enters the atmosphere, in order to reduce the effects of re-entry, or does it occur during reentry to that the propellent gases impact with the atmospheric gases ahead of the rocket protecting the rocket from being struck by the atmosphere at high velocity? Edited March 9, 2016 by codepoet Link to comment Share on other sites More sharing options...
KerbonautInTraining Posted March 9, 2016 Share Posted March 9, 2016 14 minutes ago, codepoet said: So I have always wondered about this - does the re-entry burn occur to slow the rocket down before it enters the atmosphere, in order to reduce the effects of re-entry, or does it occur during reentry to that the propellent gases impact with the atmospheric gases ahead of the rocket protecting the rocket from being struck by the atmosphere at high velocity? Just before re-entry. Link to comment Share on other sites More sharing options...
sgt_flyer Posted March 9, 2016 Share Posted March 9, 2016 (edited) 32 minutes ago, codepoet said: So I have always wondered about this - does the re-entry burn occur to slow the rocket down before it enters the atmosphere, in order to reduce the effects of re-entry, or does it occur during reentry to that the propellent gases impact with the atmospheric gases ahead of the rocket protecting the rocket from being struck by the atmosphere at high velocity? entry burn starts at ~70km altitude end ends at ~40km altitude. 'atmospheric entry' is supposed to occur above the karman line. engines should be blunt enough to detach the shock layer, but are uneven, so i guess using the exhaust plume also helps maintaining the layer away from the rocket still, the engines are already hot before reentry ignition. here's nasa's thermal imaging of CRS-4 (from stage sep to entry burn) Edited March 9, 2016 by sgt_flyer Link to comment Share on other sites More sharing options...
StrandedonEarth Posted March 9, 2016 Share Posted March 9, 2016 20 hours ago, sgt_flyer said: ouch, that definitely left a mark this time. Wow that made quite a mess of the deck. Quite the apt name for the boat, if it still loves Falcons after that. But it doesn't look like Falcon loves the barge very much Link to comment Share on other sites More sharing options...
sgt_flyer Posted March 9, 2016 Share Posted March 9, 2016 2 minutes ago, StrandedonEarth said: Wow that made quite a mess of the deck. Quite the apt name for the boat, if it still loves Falcons after that. But it doesn't look like Falcon loves the barge very much guess we're overdue for a falcon punch joke ? Link to comment Share on other sites More sharing options...
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