StrandedonEarth Posted March 10, 2019 Share Posted March 10, 2019 No, but toxic hypergolic residues would be Quote Link to comment Share on other sites More sharing options...
Xd the great Posted March 10, 2019 Share Posted March 10, 2019 38 minutes ago, tater said: The only issue with this that I see is that the landing burn itself is at such low altitude, there's not really room for a chute as backup, I'd think. I suppose it depends on how deeply they can throttle (though starting up a hypergolic is not an issue). They did do a hover test, so no problem. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted March 10, 2019 Share Posted March 10, 2019 I assume 'parachute backup for propulsive landing' means they would use the parachute method if there is some indications of problems with the SuperDracos prior to the landing attempt... not if the SuperDracos fail during landing. Quote Link to comment Share on other sites More sharing options...
tater Posted March 10, 2019 Share Posted March 10, 2019 32 minutes ago, Xd the great said: They did do a hover test, so no problem. The issue is failure modes. If the engines fail for whatever reason, then it hits the ground hard assuming the engine start is below parachute altitude. There's also the failure mode where they work, then stop working (assuming that has a non-zero probability). Propulsive landing makes more sense as a backup, because if the chutes fail, you have nothing to lose. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted March 10, 2019 Share Posted March 10, 2019 19 minutes ago, tater said: The issue is failure modes. If the engines fail for whatever reason, then it hits the ground hard assuming the engine start is below parachute altitude. There's also the failure mode where they work, then stop working (assuming that has a non-zero probability). Propulsive landing makes more sense as a backup, because if the chutes fail, you have nothing to lose. They have 8 engines, they only need 4 to land... If 1 engine fails, use another pair Quote Link to comment Share on other sites More sharing options...
MaverickSawyer Posted March 10, 2019 Share Posted March 10, 2019 1 hour ago, Xd the great said: They have 8 engines, they only need 4 to land... If 1 engine fails, use another pair Or, shut down the radially opposite engine and carry on with the other engine of pair in the pod simply throttled up. Quote Link to comment Share on other sites More sharing options...
Scotius Posted March 10, 2019 Share Posted March 10, 2019 Propulsively landing Dragon would be epic. But i doubt SpaceX will want to sink resources into this branch of Falcon\Dragon package. Unless they will want more flight data for Starship Quote Link to comment Share on other sites More sharing options...
Xd the great Posted March 10, 2019 Share Posted March 10, 2019 38 minutes ago, Scotius said: Propulsively landing Dragon would be epic. But i doubt SpaceX will want to sink resources into this branch of Falcon\Dragon package. Unless they will want more flight data for Starship They have the code. May do this for "fun" Did anyone consider using those engines for a retroptopulsion in the final moments of touchdown? Quote Link to comment Share on other sites More sharing options...
DDE Posted March 10, 2019 Share Posted March 10, 2019 1 hour ago, Scotius said: Propulsively landing Dragon would be epic. But i doubt SpaceX will want to sink resources into this branch of Falcon\Dragon package. Unless they will want more flight data for Starship They’re already sunk. 5 hours ago, StrandedonEarth said: No, but toxic hypergolic residues would be And those are an unsolvable problem why? Quote Link to comment Share on other sites More sharing options...
Xd the great Posted March 10, 2019 Share Posted March 10, 2019 9 hours ago, StrandedonEarth said: No, but toxic hypergolic residues would be Well, ask the shuttle cleaning crew to get the job done. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 10, 2019 Share Posted March 10, 2019 9 hours ago, tater said: Propulsive landing makes more sense as a backup, because if the chutes fail, you have nothing to lose. Except that you have to land several tonnes of propulsion things on those chutes, so they should be (1.5? 2?) times larger, and you could just have a backup set of chutes. Quote Link to comment Share on other sites More sharing options...
tater Posted March 10, 2019 Share Posted March 10, 2019 They could test on a cargo landing. Burn to zero velocity in mid air, then use chutes normally. Do that a few times, then try it for real. Quote Link to comment Share on other sites More sharing options...
Codraroll Posted March 10, 2019 Share Posted March 10, 2019 31 minutes ago, tater said: They could test on a cargo landing. Burn to zero velocity in mid air, then use chutes normally. Do that a few times, then try it for real. The chutes won't deploy if the velocity is zero, though. That means you'd have to do the braking maneuver at a pretty high altitude, and use chutes to carry you the last leg to the ground anyway. And even if the propulsion system worked perfectly, you'd still be screwed if the chutes were faulty, as dropping like a brick from a height of half a kilometer is just as deadly as dropping like a brick from space. Drogue chutes could achieve the same braking without having to lug lots of propellant around. Quote Link to comment Share on other sites More sharing options...
sh1pman Posted March 10, 2019 Share Posted March 10, 2019 1 minute ago, Codraroll said: to lug lots of propellant around. They’ll still need to carry lots of propellant for abort capability. Unless they vent all of it to space before reentry, it’ll still be there during the landing, unused. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted March 10, 2019 Share Posted March 10, 2019 1 hour ago, Codraroll said: The chutes won't deploy if the velocity is zero, though. That means you'd have to do the braking maneuver at a pretty high altitude, and use chutes to carry you the last leg to the ground anyway. And even if the propulsion system worked perfectly, you'd still be screwed if the chutes were faulty, as dropping like a brick from a height of half a kilometer is just as deadly as dropping like a brick from space. Drogue chutes could achieve the same braking without having to lug lots of propellant around. You could it together with parachutes to land cargo flight on land, this would make reuse of cargo version way easier. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted March 10, 2019 Share Posted March 10, 2019 1 hour ago, magnemoe said: You could it together with parachutes to land cargo flight on land, this would make reuse of cargo version way easier. The capsule hangs at an angle under the parachutes. I don't know that that is compatible with using the SuperDracos as last-second braking motors. Quote Link to comment Share on other sites More sharing options...
tater Posted March 10, 2019 Share Posted March 10, 2019 5 hours ago, Codraroll said: The chutes won't deploy if the velocity is zero, though. That means you'd have to do the braking maneuver at a pretty high altitude, and use chutes to carry you the last leg to the ground anyway. And even if the propulsion system worked perfectly, you'd still be screwed if the chutes were faulty, as dropping like a brick from a height of half a kilometer is just as deadly as dropping like a brick from space. Drogue chutes could achieve the same braking without having to lug lots of propellant around. That’s what I meant. Brake propuslively at high alt, then chutes. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted March 10, 2019 Share Posted March 10, 2019 4 hours ago, Brotoro said: The capsule hangs at an angle under the parachutes. I don't know that that is compatible with using the SuperDracos as last-second braking motors. You dont need to kill all velocity. You just need to kill all horizontal component of velocity. That makes life easier, and landing more accurate. But I thought they may try propusive landing on cargo missions. No chutes, pure propulsive landing. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted March 11, 2019 Share Posted March 11, 2019 3 hours ago, Xd the great said: You dont need to kill all velocity. You just need to kill all horizontal component of velocity. That makes life easier, and landing more accurate. But I thought they may try propusive landing on cargo missions. No chutes, pure propulsive landing. There's no penalty for firing the SuperDracos multiple times -- they are hypergolic, after all. So they could do a few quick bursts just after going subsonic, to make sure everything is firing properly. If it all checks out, commit to propulsive landing, reignite and throttle-up the engines, and translate over to OCISLY under continual power. If there are any issues, pop the drogues and proceed to a nominal splashdown. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted March 11, 2019 Share Posted March 11, 2019 Speaking of propulsively landing space capsules, look what I found looking around today! https://en.wikipedia.org/wiki/Zarya_(spacecraft) I didn't know that the Russians ever considered something like this! Quote Link to comment Share on other sites More sharing options...
tater Posted March 11, 2019 Share Posted March 11, 2019 Depends on what nasa wants. If they are returning experiments then risking them might not be ok with the customer. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 11, 2019 Share Posted March 11, 2019 (edited) 2 hours ago, Ultimate Steve said: Speaking of propulsively landing space capsules, look what I found looking around today! https://en.wikipedia.org/wiki/Zarya_(spacecraft) https://translate.google.com.tr/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http://www.buran.ru/htm/zarya.htm https://translate.google.com.tr/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http://www.buran.ru/htm/spirit.htm (on top of Mir) Edited March 11, 2019 by kerbiloid Quote Link to comment Share on other sites More sharing options...
DDE Posted March 11, 2019 Share Posted March 11, 2019 5 hours ago, Ultimate Steve said: I didn't know that the Russians ever considered something like this! Glushko wasn’t keen on Buran. Quote Link to comment Share on other sites More sharing options...
sh1pman Posted March 11, 2019 Share Posted March 11, 2019 Yep, we could have a large, reusable 8-seater capsule with propulsive landing 30 years ago. Collapse of the country isn’t great for space program funding. Quote Link to comment Share on other sites More sharing options...
DDE Posted March 11, 2019 Share Posted March 11, 2019 1 hour ago, sh1pman said: Yep, we could have a large, reusable 8-seater capsule with propulsive landing 30 years ago. Collapse of the country isn’t great for space program funding. Hey, don’t you know that Energiya-Buran is still an ongoing program? Spoiler Molniya lacks the money for an official process of closing a program. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.