Beccab Posted April 21, 2021 Share Posted April 21, 2021 2 hours ago, kerbiloid said: For sure. Until it burns Given that you said "without landing", what are you suggesting, making a full 15 meters high falcon 9 second stage just crash somewhere without burning, all this from orbital velocity? Doesn't seem safe at all Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 10 minutes ago, Beccab said: Given that you said "without landing", what are you suggesting, making a full 15 meters high falcon 9 second stage just crash somewhere without burning, all this from orbital velocity? Doesn't seem safe at all The question is, can it aerobrake down to the terminal velocity, let alone the landing. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted April 21, 2021 Share Posted April 21, 2021 Well we'll just have to see, but I wouldn't bet money against. Quote Link to comment Share on other sites More sharing options...
.50calBMG Posted April 21, 2021 Share Posted April 21, 2021 If it had a heat sheild and landing guidance, probably. SpaceX is pretty good at doing what they say they are going to do, and doing it faster than any other company or organization. Quote Link to comment Share on other sites More sharing options...
tater Posted April 21, 2021 Share Posted April 21, 2021 10 minutes ago, kerbiloid said: The question is, can it aerobrake down to the terminal velocity, let alone the landing. I'm pretty confident that math has been done by all the launch providers, and NASA, ESA, etc. They dispose of upper stages routinely, and presumably they actually design them to intentionally fail, since the goal is for them to burn up. Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted April 21, 2021 Share Posted April 21, 2021 3 hours ago, tater said: The Shuttle was designed with far less ability to model anything accurately, and worked the very first time. Do not forget all the basic research that NASA and the USAF did in the 60s on lifting bodies. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 1 minute ago, mikegarrison said: Do not forget all the basic research that NASA and the USAF did in the 60s on lifting bodies. Yes, and iirc, the original full-steel Starshiphopper has already become aluminium and covered with tiles after first tests. So, calculations are good, but actual successful aerobraking is gooder. Quote Link to comment Share on other sites More sharing options...
tater Posted April 21, 2021 Share Posted April 21, 2021 1 minute ago, mikegarrison said: Do not forget all the basic research that NASA and the USAF did in the 60s on lifting bodies. True, they absolutely did the math. I specifically mean the computational ability to do CFD at a level that was just not possible in the 60s. (maybe it was possible, but with far, far more human effort and time required). Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted April 21, 2021 Share Posted April 21, 2021 11 minutes ago, tater said: I'm pretty confident that math has been done by all the launch providers, and NASA, ESA, etc. They dispose of upper stages routinely, and presumably they actually design them to intentionally fail, since the goal is for them to burn up. As far as I can tell, mainly the goal is to make them land in the ocean. "Burning up on re-entry" is sort of a polite fiction. Quote Link to comment Share on other sites More sharing options...
tater Posted April 21, 2021 Share Posted April 21, 2021 Just now, mikegarrison said: As far as I can tell, mainly the goal is to make them land in the ocean. "Burning up on re-entry" is sort of a polite fiction. Well, people did get to see one breaking into pieces east of Seattle a few weeks ago, right? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 Many cylinders have aerobraked, but noone without turning into scrap before touching the ground. Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted April 21, 2021 Share Posted April 21, 2021 4 minutes ago, kerbiloid said: Many cylinders have aerobraked, but noone without turning into scrap before touching the ground. I think you're confusing correlation with causation. Many cylindrical objects have burned up on re-entry, but that's because none of them were designed to survive it - they weren't equipped with heat shielding or any method of attitude control. Cylinders aren't a bad re-entry vehicle shape just because a discarded cylindrical stage doesn't survive. Quote Link to comment Share on other sites More sharing options...
tater Posted April 21, 2021 Share Posted April 21, 2021 6 minutes ago, kerbiloid said: Many cylinders have aerobraked, but noone without turning into scrap before touching the ground. Are we sure of that? Seems like some might have only had a problem with the sudden stop at the end of the flight Spoiler Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted April 21, 2021 Share Posted April 21, 2021 13 minutes ago, tater said: Well, people did get to see one breaking into pieces east of Seattle a few weeks ago, right? I didn't say they don't break up along the way.... Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 3 minutes ago, tater said: Seems like some might have only had a problem with the sudden stop at the end of the flight Waiting for it with engines and head, made of Starship materials and 9 m wide. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted April 21, 2021 Share Posted April 21, 2021 12 hours ago, kerbiloid said: Lifting body is not just for terminal velocity (all of them have it ~150 m/s at last). Radial acceleration and heat distribution. Sorry - I meant 'lifting body for aerodynamic landing' - to allow for landing on wheels on a runway. I intended that to be distinct from terminal velocity - which AFAIK is the best a cylinder can do without the engines kicking in. From what I glean from Mike's thread, lifting body + control surfaces allow for a plane-like landing. Cylinder + control surfaces give you some control over where you crash absent the engine assist Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 5 minutes ago, RealKerbal3x said: I think you're confusing correlation with causation. Many cylindrical objects have burned up on re-entry, but that's because none of them were designed to survive it - they weren't equipped with heat shielding or any method of attitude control. Cylinders aren't a bad re-entry vehicle shape just because a discarded cylindrical stage doesn't survive. I just want to see an upper stage stayed structurally intact after aerobraking, according to its telemetry. Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted April 21, 2021 Share Posted April 21, 2021 Just now, kerbiloid said: I just want to see an upper stage stayed structurally intact after aerobraking, according to its telemetry. They're not designed to. Starship is. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 1 minute ago, JoeSchmuckatelli said: lifting body + control surfaces allow for a plane-like landing. It allows first of all shallow aerobraking. Just now, SOXBLOX said: They're not designed to. Starship is. Designed =/= Able Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted April 21, 2021 Share Posted April 21, 2021 2 minutes ago, JoeSchmuckatelli said: From what I glean from Mike's thread, lifting body + control surfaces allow for a plane-like landing. Cylinder + control surfaces give you some control over where you crash absent the engine assist It's often said (with some accuracy) that a brick can fly if you give it enough thrust. What's most important is the control authority. Anything with any positive coefficient of lift can control its sink rate as long as it has enough airspeed, but those lifting bodies needed LOOOONG runways because they came in really fast. However, there is a problem of airspeed management. If you have no thrust then you can only counteract drag by either losing airspeed or losing height. So you need to be able to lose height pretty steeply right up until the end, and then flare to control your sink rate just before you touch down. It's pretty much as delicate as a suicide burn for a rocket. You need everything to set up correctly (airspeed, sink rate, touchdown location, aligned with the runway direction) at just the right time, and if you have no go-around capability then you need to do it right the first time. Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted April 21, 2021 Share Posted April 21, 2021 14 minutes ago, kerbiloid said: Designed =/= Able Not always, but it can come close. And it's getting closer. The T-7 Red Hawk trainer/light attack aircraft was designed and tested almost entirely electronically. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted April 21, 2021 Share Posted April 21, 2021 35 minutes ago, kerbiloid said: Yes, and iirc, the original full-steel Starshiphopper has already become aluminium and covered with tiles after first tests. Still stainless steel. TPS evolved from transpiration to tiles but otherwise still present. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 21, 2021 Share Posted April 21, 2021 1 minute ago, SOXBLOX said: Not always, but it can come close. And it's getting closer. The T-7 Red Hawk trainer/light attack aircraft was designed and tested almost entirely electronically. N-1 was cancelled after 4 tests. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted April 21, 2021 Share Posted April 21, 2021 Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted April 21, 2021 Share Posted April 21, 2021 1 minute ago, kerbiloid said: N-1 was cancelled after 4 tests. Four flights. The Soviets were too cheap to build a test stand. Quote Link to comment Share on other sites More sharing options...
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