tater Posted February 9, 2019 Share Posted February 9, 2019 3 min 39 sec is a long burn. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 9, 2019 Share Posted February 9, 2019 20 minutes ago, tater said: 3 min 39 sec is a long burn. That's Raptor. They have no reason to test Merlins that long at this point. And nearly 4 minutes? That's a full mission-representative Starhopper burn. Starhopper is staying under 5 km so that's the sort of burn length we would expect for a full-duration mission. Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted February 9, 2019 Share Posted February 9, 2019 4 minutes ago, sevenperforce said: That's Raptor. They have no reason to test Merlins that long at this point. And nearly 4 minutes? That's a full mission-representative Starhopper burn. Starhopper is staying under 5 km so that's the sort of burn length we would expect for a full-duration mission. And it sounds like they're testing throttle responce, too. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted February 9, 2019 Share Posted February 9, 2019 4 minutes ago, sevenperforce said: That's Raptor. They have no reason to test Merlins that long at this point. And nearly 4 minutes? That's a full mission-representative Starhopper burn. Starhopper is staying under 5 km so that's the sort of burn length we would expect for a full-duration mission. Are they testing Raptor at the same location they test the F9 stages? AFAIK, IIRC, every F9 booster does a full-duration test burn as part of its qualification/acceptance testing, but I don't know if they do that before each reflight. Quote Link to comment Share on other sites More sharing options...
tater Posted February 9, 2019 Share Posted February 9, 2019 Quote Link to comment Share on other sites More sharing options...
magnemoe Posted February 9, 2019 Share Posted February 9, 2019 On 2/7/2019 at 2:12 PM, KSK said: Depends whether you take the measurement behind or in front of the injector. As i understand raptor is all hot gas after the turbo pump, Quote Link to comment Share on other sites More sharing options...
Xd the great Posted February 9, 2019 Share Posted February 9, 2019 How does the drag coefficinet of starship compare to other capsules and the space shuttle? Quote Link to comment Share on other sites More sharing options...
tater Posted February 9, 2019 Share Posted February 9, 2019 16 minutes ago, Xd the great said: How does the drag coefficinet of starship compare to other capsules and the space shuttle? I'd expect it's between the two due to the reduced wing area. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted February 9, 2019 Share Posted February 9, 2019 1 hour ago, tater said: I'd expect it's between the two due to the reduced wing area. So how can they keep peak temperature at 1700K? The space shuttle had the same reentry max temperature yet with larger wings... Quote Link to comment Share on other sites More sharing options...
MaverickSawyer Posted February 9, 2019 Share Posted February 9, 2019 Higher density, for lack of a better description. The shuttle was pretty heavy compared to its volume, while the Starship, on reentry, will be fairly low mass relative to its volume. Quote Link to comment Share on other sites More sharing options...
KSK Posted February 9, 2019 Share Posted February 9, 2019 5 hours ago, magnemoe said: As i understand raptor is all hot gas after the turbo pump, You are correct of course. Scratch one perfectly good joke to the realities of rocket engineering. Quote Link to comment Share on other sites More sharing options...
DDE Posted February 9, 2019 Share Posted February 9, 2019 On 2/8/2019 at 6:42 AM, sevenperforce said: "Frag"....what a guy. Well, I still dream of Roscosmos going pants-on-head and falconizing Soyuz-2.1v, since it’s the red-headed stepchild of the cirrent line-up. It may be structurally incapable of supporting legs. Which leaves is with only one option: make a couple tune-ups to the Tulip. Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted February 9, 2019 Share Posted February 9, 2019 9 hours ago, Xd the great said: How does the drag coefficinet of starship compare to other capsules and the space shuttle? Between the higher angle of attack and the empty fuel tanks, it has both more area and less density. Shuttle ditched the primary fuel tank just short of orbit- the rest of the shuttle is packed full. Quote Link to comment Share on other sites More sharing options...
Starman4308 Posted February 10, 2019 Share Posted February 10, 2019 11 hours ago, Rakaydos said: Between the higher angle of attack and the empty fuel tanks, it has both more area and less density. Shuttle ditched the primary fuel tank just short of orbit- the rest of the shuttle is packed full. While I do suspect the Starship will have a lower ballistic coefficient, that isn't strictly true. The Shuttle payload bay was (usually) empty, the crew cabin had a reasonably amount of empty space, the OMS tanks were drained, etc. Granted, none of that stopped the Shuttle from being something that didn't glide so much as it fell to the runway. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted February 10, 2019 Share Posted February 10, 2019 (edited) The shuttle weighted 76 to 80 tonnes dry mass, but was only 37 meters in length with a 23 meter wingspam. Starship probably has a dry mass of 85, 55m long, but was 9 meter in diameter and had a smaller wingspam. Reentry weight of the shuttle was about 80 to 85 tonnes, while that of starship may exceed 100 tonnes. The shuttle relied on wings to remain high up in the atmosphere, while to starship relied on airbrakes to slow down. Edited February 10, 2019 by Xd the great Quote Link to comment Share on other sites More sharing options...
Xd the great Posted February 10, 2019 Share Posted February 10, 2019 So maybe the starship would have a reentry temperature of 1900K if it werent for the reflective stainless steel. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 10, 2019 Share Posted February 10, 2019 12 hours ago, Xd the great said: The shuttle weighted 76 to 80 tonnes dry mass, but was only 37 meters in length with a 23 meter wingspam. Starship probably has a dry mass of 85, 55m long, but was 9 meter in diameter and had a smaller wingspam. Reentry weight of the shuttle was about 80 to 85 tonnes, while that of starship may exceed 100 tonnes. The shuttle relied on wings to remain high up in the atmosphere, while to starship relied on airbrakes to slow down. Back of the envelope says the shuttle had a cross-sectional area of 346 square meters while Starship will cross-section at around 460 square meters without counting any portion of the articulated wings. The new Starship will be lighter than the 2017 IAC version due to use of stainless. Starship will be positively balloon-like compared to the famous flying brick. Shuttle's wings were actually far too good at providing lift; they developed so much lift that they would have pushed the vehicle to coast into a higher altitude where lower speeds would stall them out. Hence the strict 40-degree AoA and the infamous S-curves. The shuttle's wings were sized for glide, approach, and landing, not entry. Starship will have a higher angle of attack, meaning it will decelerate more before hitting the thicker part of the atmosphere. Its airbrakes are are for controlling vehicle attitude; contribution to drag is just a bonus. Quote Link to comment Share on other sites More sharing options...
tater Posted February 11, 2019 Share Posted February 11, 2019 Quote Link to comment Share on other sites More sharing options...
RedKraken Posted February 11, 2019 Share Posted February 11, 2019 (edited) 268 bar for 20ms (?).....a new high bar. Tweet storm : Edited February 11, 2019 by RedKraken Quote Link to comment Share on other sites More sharing options...
tater Posted February 11, 2019 Share Posted February 11, 2019 Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 11, 2019 Share Posted February 11, 2019 (edited) Not an extensible nozzle a la Centaur. Also, this is incredible: Elon says that the 270 bar is without deep cryo propellants. The screenshot he posted was an actual snap of the pressure vs time; time is the x-axis in seconds. 11 second fire. Edited February 11, 2019 by sevenperforce Quote Link to comment Share on other sites More sharing options...
tater Posted February 11, 2019 Share Posted February 11, 2019 Gotta love an Elon tweet storm. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 11, 2019 Share Posted February 11, 2019 1 hour ago, RedKraken said: 268 bar for 20ms (?).....a new high bar. Tweet storm : SS is way cheaper than Lithium-aluminum alloy, but 38 engines vs 10? 6 minutes ago, tater said: Gotta love an Elon tweet storm. It's like crack. Also, Elon says he has a copy of Ignition! on his bedside table. Quote Link to comment Share on other sites More sharing options...
tater Posted February 11, 2019 Share Posted February 11, 2019 6 minutes ago, sevenperforce said: SS is way cheaper than Lithium-aluminum alloy, but 38 engines vs 10? I simply could not wrap my head around that. Even if Merlins are way cheaper than we imagine (Mueller said they could make one a day, right?), can they possibly be so cheap they don't dominate costs? Quote Link to comment Share on other sites More sharing options...
Xd the great Posted February 11, 2019 Share Posted February 11, 2019 13 minutes ago, tater said: I simply could not wrap my head around that. Even if Merlins are way cheaper than we imagine (Mueller said they could make one a day, right?), can they possibly be so cheap they don't dominate costs? Trashcan alert! Dude, how much are the contractors earning? Elon once said they avoid space contractors... Quote Link to comment Share on other sites More sharing options...
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