YNM Posted February 4, 2021 Share Posted February 4, 2021 5 hours ago, mikegarrison said: In the case of something that is simply falling rather than trying to generate lift, I don't think angle of attack is particularly meaningful. I mean, Shuttle practically flew in at freefall vertical velocity yet it's still counted as flying XD Starship would re-enter roughly the same way as in the tests right ? At least the ideas so far ? Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted February 4, 2021 Share Posted February 4, 2021 33 minutes ago, JoeSchmuckatelli said: Why put Sn10 anywhere near where Sn9 might FOD the heck out of it? PR? It certainly looked impressive to see them both standing there. One risk of this "build before test" strategy is that they may have hardware built that they realize is too out of date to be used. Didn't they just scrap some of their in-progress builds because they are moving to a new design blockpoint? Maybe they know SN10 is not particularly useful anymore and so it didn't really matter if it gets damaged. At least they avoided the fate of having SN9 come down directly on SN10, which would have have made some blooper reels for sure. 33 minutes ago, YNM said: I mean, Shuttle practically flew in at freefall vertical velocity yet it's still counted as flying XD Starship would re-enter roughly the same way as in the tests right ? At least the ideas so far ? Shuttle came in basically like a ballistic capsule (similar to how I understand Starship is intended to come in), but then transitioned into flying like an airplane with airplane-like control surfaces and a lifting wing/body. From what I've seen, SpaceX does not intend to use those flaps to generate lift. They are more like spoilers or airbrakes than wings. I imagine they will have some amount of cross-range capability just by steering their drag vector around, but I don't think "angle of attack" is really a useful way to look at what they are trying to do. (That is, if I correctly understand what it is that they are trying to do....) Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 4, 2021 Share Posted February 4, 2021 21 minutes ago, mikegarrison said: From what I've seen, SpaceX does not intend to use those flaps to generate lift. They are more like spoilers or airbrakes than wings. I imagine they will have some amount of cross-range capability just by steering their drag vector around, but I don't think "angle of attack" is really a useful way to look at what they are trying to do. (That is, if I correctly understand what it is that they are trying to do....) The flaps do not generate lift but the fuselage itself generates significant body lift. They use the flaps to control attitude and then they use the body lift vector to control where they are headed. It’s the same with the first stage on Falcon 9. They use the grid fins post-entry-burn to tilt over the cylinder to a fairly ridiculous angle of attack and end up with a cylindrical body lift of nearly 1. With Starship the body lift can be significantly higher. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 4, 2021 Share Posted February 4, 2021 28 minutes ago, mikegarrison said: From what I've seen, SpaceX does not intend to use those flaps to generate lift. They are more like spoilers or airbrakes than wings. I imagine they will have some amount of cross-range capability just by steering their drag vector around, but I don't think "angle of attack" is really a useful way to look at what they are trying to do. (That is, if I correctly understand what it is that they are trying to do....) Starship is supposed to be able to use the flaps to be able to help the ship get more accurately to the landing area - but yeah, not like shuttle to fly and land, 'as a plane'. However - there will be a real element of 'falling with style' to what they can achieve via the flaps.... even if it does fall short of 'flight'. Quote Link to comment Share on other sites More sharing options...
paul_c Posted February 4, 2021 Share Posted February 4, 2021 Space Shuttle didn't really use lift in the conventional airplane sense, of having wings which generated enough lift to counterbalance the weight; and the thrust from an engine to counterbalance drag and fly "straight and level (and constant speed)". It can be thought of as a thing which had different drag in different orientations, so it altered its orientation (angle of attack) to use drag to slow down and also have directional control. Another way to think of it is, it was able to trade forwards airspeed to reduce vertical descent rate. In that sense, Starship is very similar. Compared to a sphere, which travels ballistically, Starship uses its body to act as a 'wing' or an aerodynamic surface which presents significantly more drag in one direction than the other; and alter its orientation too, so that difference can be used for control. I dare say Space Shuttle if you analysed its shape, you could say the 'body' plays a significant role in the aerodynamic control as well as the wings. The difference is, the Starship uses its flaps merely to alter its orientation. I guess in an aeronautical sense you'd actually call them canards/aerolons/elevators. Quote Link to comment Share on other sites More sharing options...
tater Posted February 4, 2021 Share Posted February 4, 2021 Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted February 4, 2021 Share Posted February 4, 2021 2 hours ago, paul_c said: Space Shuttle didn't really use lift in the conventional airplane sense Sure it did. You are correct that it was not able to enter steady-state cruise, which is when L=W and T=D. But neither do any other gliders, and they certainly are airplanes that "use lift in the conventional airplane sense". Quote Link to comment Share on other sites More sharing options...
tater Posted February 4, 2021 Share Posted February 4, 2021 Quote Link to comment Share on other sites More sharing options...
tater Posted February 4, 2021 Share Posted February 4, 2021 Live and good to go so far. Quote Link to comment Share on other sites More sharing options...
paul_c Posted February 4, 2021 Share Posted February 4, 2021 1 minute ago, mikegarrison said: Sure it did. You are correct that it was not able to enter steady-state cruise, which is when L=W and T=D. But neither do any other gliders, and they certainly are airplanes that "use lift in the conventional airplane sense". I guess my phraseology isn't exact. I mean, it didn't have a set of wings which were shaped to maximise lift/minimise drag, while the body was generally neutral. It wasn't an airplane, it didn't "do" aerodynamic powered flight horizontally (it did vertical lift horizontal land). Yes it was a glider, yes it obviously used "lift" but it was as much about continuously reducing its airspeed as it "flew" in a pretty rigidly defined flight profile, rather than what you might call a conventional glider flight profile where it aims to minimise vertical speed (loss of altitude) while flying at steady speed in between; and increasing altitude in thermals etc. It had a huge amount of energy at the start of its descent compared to an airplane and did sweeping S turns etc to continuously lose/manage that energy, once you start the descent the clock is ticking and one way or another you'd hit the ground in xx.xx after the initiation. There wasn't much of a window to control when, just where. It was a wide brick with a big belly which did a BIG flare to trade vertical speed for airspeed, then land pretty fast on some pretty special wheels which could cope with the speeds. Its similar to Starship in a proportion of aspects. Starship has control (in theory...not yet in practice) by firing engines to do the last phase of landing; of course it too has a somewhat narrow window, due to weight/amount of fuel and I dare say, the need to burn off most of the fuel to avoid an overweight landing. Quote Link to comment Share on other sites More sharing options...
Guest Posted February 4, 2021 Share Posted February 4, 2021 you know what's great to hear, a launch tonight and a launch on friday. Besides spacex, I don't recall hearing that for a company ever really. Quote Link to comment Share on other sites More sharing options...
tater Posted February 4, 2021 Share Posted February 4, 2021 Nominal parking orbit, 5th landing for this booster. This booster flew 27 days ago. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted February 4, 2021 Share Posted February 4, 2021 Nice! Quote Link to comment Share on other sites More sharing options...
Geonovast Posted February 4, 2021 Share Posted February 4, 2021 Absolutely loved the lighting up of the grid fins from the upper stage exhaust. Beautiful landing, too. Quote Link to comment Share on other sites More sharing options...
tater Posted February 4, 2021 Share Posted February 4, 2021 He just posted this from tonight. Must have been near each other: Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted February 4, 2021 Share Posted February 4, 2021 16 minutes ago, paul_c said: I guess my phraseology isn't exact. I mean, it didn't have a set of wings which were shaped to maximise lift/minimise drag, while the body was generally neutral. It wasn't an airplane, it didn't "do" aerodynamic powered flight horizontally (it did vertical lift horizontal land). Yes it was a glider, yes it obviously used "lift" but it was as much about continuously reducing its airspeed as it "flew" in a pretty rigidly defined flight profile, rather than what you might call a conventional glider flight profile where it aims to minimise vertical speed (loss of altitude) while flying at steady speed in between; and increasing altitude in thermals etc. It had a huge amount of energy at the start of its descent compared to an airplane and did sweeping S turns etc to continuously lose/manage that energy, once you start the descent the clock is ticking and one way or another you'd hit the ground in xx.xx after the initiation. There wasn't much of a window to control when, just where. It was a wide brick with a big belly which did a BIG flare to trade vertical speed for airspeed, then land pretty fast on some pretty special wheels which could cope with the speeds. Its similar to Starship in a proportion of aspects. Starship has control (in theory...not yet in practice) by firing engines to do the last phase of landing; of course it too has a somewhat narrow window, due to weight/amount of fuel and I dare say, the need to burn off most of the fuel to avoid an overweight landing. I don't really understand what you are trying to argue here. There is no doubt whatsoever that the shuttle had massively more cross-range capability than Starship will. Sure, the shuttle didn't have an L/D of 50 or anything, but it had three-axis control and could fly down and land like a conventional airplane. Starship is really more of what you might called "controlled falling", like a skydiver who uses his limbs to have some control. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 4, 2021 Share Posted February 4, 2021 (edited) 5 hours ago, mikegarrison said: One risk of this "build before test" strategy is that they may have hardware built that they realize is too out of date to be used. Starship follows N1 even in this. Instead of testing all critical gimbal angles of the the triple-engine bottom on ground, then attach, they prefer to test it in air. At least, they tried with 3 instead of all 28, unlike N1 did. 1 hour ago, mikegarrison said: Sure it did. You are correct that it was not able to enter steady-state cruise, which is when L=W and T=D. But neither do any other gliders, and they certainly are airplanes that "use lift in the conventional airplane sense". The test instance of Buran was flying like a plane by turbojets, and probably the proto-Shuttle did. Doesn't this mean, they are "normal" airplanes? Isn't B2 an airplane, when it looks even less airplanish than both of them? Who cares what produces the lifting force: hull or wing(s)... Edited February 4, 2021 by kerbiloid Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted February 4, 2021 Share Posted February 4, 2021 Looks like SN10 was not damaged by another vehicle RUD'ing right next to it! Also, AMAZING official SpaceX pic: (from SpaceX's Flickr https://www.flickr.com/photos/spacex/50905786603/in/photostream/) Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted February 4, 2021 Share Posted February 4, 2021 34 minutes ago, kerbiloid said: The test instance of Buran was flying like a plane by turbojets, and probably the proto-Shuttle did. No, the test shuttle was simply dropped from a 747. Unlike Buran they never built a powered glide test Shuttle. 37 minutes ago, kerbiloid said: Isn't B2 an airplane, when it looks even less airplanish than both of them? Who cares what produces the lifting force: hull or wing(s)... The Shuttle, Buran, the X-37B, the Dreamchaser, the lifting body airplanes from the 1960s, etc. all behave like airplanes in that they can control their sink rate, line up with a runway, and land horizontally under the influence of their own aerodynamic lift. I see this as quite different from capsules that land by parachute or vehicles that land vertically with propulsive thrust. Of course there VTOL airplanes and helicopters too.... Quote Link to comment Share on other sites More sharing options...
RCgothic Posted February 4, 2021 Share Posted February 4, 2021 Starship navigates to its destination using lift. Drag is parallel to the airstream. Without lift Starship would be unable to steer. Most of the lift comes from the body. A little comes from the flaps. Yes, these surfaces are stalled. That doesn't mean they produce no lift, only that the lift to drag ratio is poor. Quote Link to comment Share on other sites More sharing options...
Flavio hc16 Posted February 4, 2021 Share Posted February 4, 2021 Now....is he being sarcastic or honestly straightforward? Imho it might be the 2nd this time, as we already saw dumb mistakes done ( sn3 explosion). If I'm right, we might see a 3 engine relight for landing for sn10 Quote Link to comment Share on other sites More sharing options...
GuessingEveryDay Posted February 4, 2021 Share Posted February 4, 2021 @tater. You need to get some sleep. Quote Link to comment Share on other sites More sharing options...
RyanRising Posted February 4, 2021 Share Posted February 4, 2021 32 minutes ago, Flavio hc16 said: Now....is he being sarcastic or honestly straightforward? Imho it might be the 2nd this time, as we already saw dumb mistakes done ( sn3 explosion). If I'm right, we might see a 3 engine relight for landing for sn10 It seems weird they wouldn't have thought to implement this already, esp. since "engine-out capability on landing" was one of the benefits espoused a while back (though I can't remember where.) Maybe they were only thinking to test the normal flip maneuver? Also, funny how "Off Twitter for a while" turned into "Off Twitter for a day." Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted February 4, 2021 Share Posted February 4, 2021 8 minutes ago, RyanRising said: Also, funny how "Off Twitter for a while" turned into "Off Twitter for a day." Elon has had Twitter breaks previously, they've never lasted more than a couple of days Quote Link to comment Share on other sites More sharing options...
Spaceception Posted February 4, 2021 Share Posted February 4, 2021 28 minutes ago, RyanRising said: It seems weird they wouldn't have thought to implement this already, esp. since "engine-out capability on landing" was one of the benefits espoused a while back (though I can't remember where.) Maybe they were only thinking to test the normal flip maneuver? Also, funny how "Off Twitter for a while" turned into "Off Twitter for a day." Well, isn't the engine flip supposed to be replaced with a thruster flip at some point? And then one engine would work once it's already upright? Quote Link to comment Share on other sites More sharing options...
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