Quote from: Lars_J on 07/07/2013 01:31 amHe said what he said. He called the first stage for the 1st v1.1 "F9-R". SpaceX can decide to call things whatever they want.When did he say that? (Asked respectfully!
He said what he said. He called the first stage for the 1st v1.1 "F9-R". SpaceX can decide to call things whatever they want.
Elon Musk@elonmusk1st firing of Falcon 9-R advanced prototype rocket. Over 1M lbs thrust, enough to lift skyscraper pic.twitter.com/AUCsWTw77E
https://twitter.com/elonmusk/status/341405518566395904QuoteElon Musk@elonmusk1st firing of Falcon 9-R advanced prototype rocket. Over 1M lbs thrust, enough to lift skyscraper pic.twitter.com/AUCsWTw77E
Are we 100% that F9 v1.1 is going to fly the same 180s / Mach ~10 path to separation as v1.0?
Quote from: Lars_J on 07/07/2013 01:31 amQuote from: ClaytonBirchenough on 07/07/2013 01:17 amQuote from: docmordrid on 07/07/2013 01:13 amYup - that's the reference I was basing my question on. So again, could we be looking at a 02:00.00 to ~02:20.00 first stage burn or is it too early to speculate?F9-R is not Falcon v1.1. The statement Musk made may not apply to the v1.1 flights. He said what he said. He called the first stage for the 1st v1.1 "F9-R". SpaceX can decide to call things whatever they want.Falcon 9-R is an evolvable design so ever time the rocket flys, there may be some changes (upgrades) made.
Quote from: ClaytonBirchenough on 07/07/2013 01:17 amQuote from: docmordrid on 07/07/2013 01:13 amYup - that's the reference I was basing my question on. So again, could we be looking at a 02:00.00 to ~02:20.00 first stage burn or is it too early to speculate?F9-R is not Falcon v1.1. The statement Musk made may not apply to the v1.1 flights. He said what he said. He called the first stage for the 1st v1.1 "F9-R". SpaceX can decide to call things whatever they want.
Quote from: docmordrid on 07/07/2013 01:13 amYup - that's the reference I was basing my question on. So again, could we be looking at a 02:00.00 to ~02:20.00 first stage burn or is it too early to speculate?F9-R is not Falcon v1.1. The statement Musk made may not apply to the v1.1 flights.
Yup - that's the reference I was basing my question on. So again, could we be looking at a 02:00.00 to ~02:20.00 first stage burn or is it too early to speculate?
Obviously this is approximate, but consistent with SpaceX intention to reduce staging velocity from 3000 to 2000 m/s.
Another error I have made could be the guesstimate of 236000 lbs (wet, including payload) for the second stage from discussions on this forum, a larger second stage would be beneficial. (If anyone have better numbers, please let me know)
Wouldn't a mass of 236000 lbs. imply a thrust to weight ratio <1 for the second stage?
Wouldn't a mass of 236000 lbs. imply a thrust to weight ration <1 for the second stage?
Keep in mind the GH is a test bed with very over designed legs for off nominal landing during testing, not a production rocket. Presumably the insulation is to keep the metal in those legs from losing temper or otherwise taking damage but needing to replace that insulation after every *TEST* is not a big deal. It's not like having a bit of extra flame in the vicinity of the Merlin exhaust is likely to hurt anything.
Quote from: ClaytonBirchenough on 07/07/2013 10:28 amWouldn't a mass of 236000 lbs. imply a thrust to weight ration <1 for the second stage? Edit: After running the numbers I've found a better answer, considering any stage 2 mass, as Joffan suggested.I simulated LEO performance for stage 2 mass between 100´000 lbs - 400´000 lbs (graph attached) using the corresponding required delta-v for LEO, which depends on time-to-orbit, which depends on stage configurations. For LEO I use 200x200, 26 deg inclination from Boca Chica.Depending on how you optimize stage 2 mass, for reusability or not, there will be two different optimal configurations; 240klbs for non-reusable and 330klbs for reusable. Stage 2 MassScenarioLEO (kg)Staging (mach)Staging (s)Time to LEO (s)240 klbsuse once16191~9184595.4240 klbsreuse12905~7.6168594.9330 klbsuse once15793~7.2164760330 klbsreuse13312~6.2149.63757conclusionIf my calculations are correct, and SpaceX prioritise design for reusability, the mass of stage 2 should be ~330'000 lbs, with a stage 1 burn time of ~150s (2:30), delivering ~13mT to LEO. If we assume SpaceX will do no "use once" launches, all launches will be capable of delivering at least 13 mT to LEO and have spare capacity to iteratively progress towards full reusability. Given this, it's reasonable to assume SpaceX design requirement for stage 1 full duration burn was 150sguesstimates:Dry/wet ratio s1: 3.5% when non-reusable (no legs), 5% when reusable (with legs, etc)Dry/wet ratio s2: 3.55% (from cambrianera's estimate)Residual fuel: 1% when non-reusable, 8% when reusable (2800 m/s residual delta-v)Total mass of stack: 0.8 times thrust at liftoff (1.323 Mlbf @ SL)calculation and full table:http://tinyurl.com/Falcon9R-3
Quote from: Okie_Steve on 07/07/2013 12:36 amKeep in mind the GH is a test bed with very over designed legs for off nominal landing during testing, not a production rocket. Presumably the insulation is to keep the metal in those legs from losing temper or otherwise taking damage but needing to replace that insulation after every *TEST* is not a big deal. It's not like having a bit of extra flame in the vicinity of the Merlin exhaust is likely to hurt anything.Could some of the heat or exhaust from the engine be used to power the leg actuators? Would that be a useful approach to take?
Quote from: sanman on 07/07/2013 09:01 pmQuote from: Okie_Steve on 07/07/2013 12:36 amKeep in mind the GH is a test bed with very over designed legs for off nominal landing during testing, not a production rocket. Presumably the insulation is to keep the metal in those legs from losing temper or otherwise taking damage but needing to replace that insulation after every *TEST* is not a big deal. It's not like having a bit of extra flame in the vicinity of the Merlin exhaust is likely to hurt anything.Could some of the heat or exhaust from the engine be used to power the leg actuators? Would that be a useful approach to take?Unnecessary complication. I would expect a simple mechanical solution, eg springs.
^Its lbs, not kg? But 150t is still far too heavy.
"SpaceX's Merlin 1D engine has achieved a full mission duration firing and multiple restarts at target thrust and specific impulse (Isp). The engine firing was for 185 seconds with 147,000 pounds of thrust, the full duration and power required for a Falcon 9 rocket launch. The tests took place at SpaceX's rocket development facility in McGregor, Texas. The Merlin 1D builds on the proven technology of the Merlin engines used on the first three flights of Falcon 9, including the recent historic mission to the International Space Station." --- Space X(explanation on 1D Melrlin Engine Testing...Youtube)As you can see from Space X Merlin 1D engine test explanation, the "full duration" of stage one for Falcon 1.1 is 3 minutes. So far Space X has only reached about two minutes testing with all 9 engines of Falcon 1.1 together. It seems to me quite a leap of faith Space X would go on with production and launch w/o full duration 3-minute by concluding the cause for the aborts is test stand environment related not hardware issues with the stages. It's useful to note Merlin 1D might qualify perfectly in stand alone full duration tests again and again. But when configured with other 9 engines together the additional thermal and kinetic energy produced from the 50% more powerful thrust may be surpassing the coping margins of some of the engine components. Or, if not the engine components, other parts of the stages!For reasons stated above I find very hard to think Space X would go on with launch w/o doing a full duration 3-minute test. If full duration of F1.1 first stage is truly 3 minutes as mentioned by Space X, it would be a gigantic leap of faith for Space X to conclude that the rocket would operate properly past 2-minutes when that has not been proven on the ground!!!
For reasons stated above I find very hard to think Space X would go on with launch w/o doing a full duration 3-minute test. If full duration of F1.1 first stage is truly 3 minutes as mentioned by Space X, it would be a gigantic leap of faith for Space X to conclude that the rocket would operate properly past 2-minutes when that has not been proven on the ground!!!