Skiver Veteran Posted February 9, 2018 Veteran Share Posted February 9, 2018 Hopefully not stupid question time... I found myself in a bit of a problem yesterday when someone was questioning why the Tesla and why not just something simple etc. Initially, I responded with well it had to be something Heavy, it's Falcon Heavy and it's designed for heavy lifting etc. I then realised, a Tesla actually isn't that heavy! From some very quick google searches, it looks like a Tesla Roadster weighs in at around 2900lbs and a Falcon 9 can lift 18,000lbs to GTO so unless I'm misunderstanding something, Falcon 9 was quite capable of this mission. I believe the boosters were never really pushed to full throttle and I'm sure they would have had a fair amount more fuel in the tanks (if they were full at launch). Was this a good test for Falcon Heavy? Should Elon have elected for something even heavier? Link to comment Share on other sites More sharing options...
anthdci Posted February 9, 2018 Share Posted February 9, 2018 18 minutes ago, Skiver said: Was this a good test for Falcon Heavy? Should Elon have elected for something even heavier? they could have, but it was a test, would it have been worth risking it with something heavier? It was also going towards the mars orbit so that GTO figure isn't important, it'll be less than that. the tanks will have been full, I think the centre ran out of the chemical it uses to re-light the engines rather than the fuel itself. Link to comment Share on other sites More sharing options...
Skiver Veteran Posted February 9, 2018 Veteran Share Posted February 9, 2018 Just now, anthdci said: they could have, but it was a test, would it have been worth risking it with something heavier? It was also going towards the mars orbit so that GTO figure isn't important, it'll be less than that. the tanks will have been full, I think the centre ran out of the chemical it uses to re-light the engines rather than the fuel itself. Oh yeah, I understand the centre core issue. I only referenced GTO as a reference to the details Space X publish - X lbs to LEO and Y lbs to GTO which takes more fuel, so in theory, by looking at GTO we're looking at its rough max intended specification. I guess the problem is, if you were looking to throw your million dollar satellite(s) into orbit and required a heavy lifter, the Falcon Heavy has only proven it can fly, not actually lift a heavy load. I'd almost want it to do another test with a much heavier and representative load. I think Falcon Heavy has a rough planned launch for the US DoD in June? anthdci 1 Share Link to comment Share on other sites More sharing options...
DocM Posted February 9, 2018 Author Share Posted February 9, 2018 (edited) Not much mass is required. From the data they got vs their preflight projections they can model other masses. As to why not launch a real payload - historically about 30-50% of maiden flight launches fail, so why risk a $multi-million$ satellite? Delta IV Heavy: wrong orbit Ariane 5: exploded Electron: telemetry failure Falcon 1 failed 3 times before achieving orbit Edited February 9, 2018 by DocM Link to comment Share on other sites More sharing options...
Skiver Veteran Posted February 9, 2018 Veteran Share Posted February 9, 2018 4 minutes ago, DocM said: Not much mass is required. From the data they got vs their preflight projections they can model other masses. As to why not launch a real payload - historically about 30-50% of maiden flight launches fail, so why risk a $multi-million$ satellite? Delta IV Heavy: wrong orbit Ariane 5: exploded Electron: telemetry failure etc. Don't get me wrong, I absolutely don't think they should have put a multi-million anything on there. Surely they could have just engineered a 20,000lbs block of something and used that. It wouldn't be as cool sure, but it would have been realistic of a test if they don't plan to do any more testing? The problem with models is they aren't real, sure they can say on paper based on X we predict Y but as you say, a lot of early flights end with failure so I don't think Space X should rest on their laurels that this went near perfect and call it a job well done. I guess another way of looking at this is, do Space X want their first commercial flight with a more realistic load to be the DoD? Given the number of contracts that can come their way by successful launches, I think I'd want to be a lot more sure that they can be from this test. Link to comment Share on other sites More sharing options...
DocM Posted February 9, 2018 Author Share Posted February 9, 2018 Whose payload would it be? Even with insurance risking your $300m bird on a new rocket at higher schedule risk, also risking losing that revenue stream until a reflight years later, is a good way to ###### off the shareholders. Link to comment Share on other sites More sharing options...
DocM Posted February 9, 2018 Author Share Posted February 9, 2018 (edited) 14 hours ago, Unobscured Vision said: That thing is zipping right along. As any sportscar should be. Zipping along because FH delivered an insane amount of delta-V to it's backside. From Australia, ~493,000 km, magnitude 16 http://spaceweathergallery.com/indiv_upload.php?upload_id=142537 Quote Observation of 2018-017A (Tesla & Starman) using the remote telescope iT32 from Siding Spring (Q62). The craziest object I could capture so far with a telescope. Edited February 9, 2018 by DocM Steven P. and Unobscured Vision 2 Share Link to comment Share on other sites More sharing options...
bguy_1986 Posted February 9, 2018 Share Posted February 9, 2018 Is it possible they packed the trunk full of weights or the custom Tesla mount? I assumed they had it loaded down to get close to a real payload. Link to comment Share on other sites More sharing options...
DocM Posted February 9, 2018 Author Share Posted February 9, 2018 "Real" payloads can run under 500kg, and the Dove Earth observation satellites run under 5kg and are launched by the dozens. bguy_1986 1 Share Link to comment Share on other sites More sharing options...
Draconian Guppy Posted February 9, 2018 Share Posted February 9, 2018 Unobscured Vision 1 Share Link to comment Share on other sites More sharing options...
DocM Posted February 9, 2018 Author Share Posted February 9, 2018 Great sonic booms Unobscured Vision, +E.Worm Jimmy and vishal1082 3 Share Link to comment Share on other sites More sharing options...
SALSN Posted February 10, 2018 Share Posted February 10, 2018 22 hours ago, Skiver said: ... a Falcon 9 can lift 18,000lbs to GTO so unless I'm misunderstanding something, Falcon 9 was quite capable of this mission. The falcon 9 could have taken the car to GTO, but it did not just go to GTO it's orbit is going almost all the way to the asteroid belt. So yes, the FH could have taken up a lot more, but it would not have gone as far. Not sure if it might have been better, test wise, to load up as much weight as possible to test that capability, but this mission was surely much more interesting :-) DocM, +E.Worm Jimmy and Unobscured Vision 3 Share Link to comment Share on other sites More sharing options...
DocM Posted February 10, 2018 Author Share Posted February 10, 2018 (edited) The real test was the 6+ hour coast and restart for DoD. That's by necessity going to result in a loss of LOX due to boiloff, about 1/3 of what they started with, which limited how far they could toss the Tesla after restarting. Doing the Mars insertion ASAP (larger props load) would have tossed it further. bguy_1986, SALSN and Unobscured Vision 3 Share Link to comment Share on other sites More sharing options...
Unobscured Vision Posted February 10, 2018 Share Posted February 10, 2018 (edited) An educated guess would see SpaceX refining the S2 so that it mitigates the LOX boiloff issue. There are things SpaceX can do, but it would require a significant redesign of their S2 tankage and the plumbing hardware which could include adding a set of radiators, cryocoolers, insulators, etc ... See the problem? Anything and everything that SpaceX could do would add weight to the second stage -- weight that otherwise would be used to toss payloads. Link to comment Share on other sites More sharing options...
DocM Posted February 10, 2018 Author Share Posted February 10, 2018 (edited) And why do that R&D when they have a MUCH more capable vehicle in the wings? Launch BFS into LEO, send up a few tankers to refill it and preposition return props at the destination, and you could easily visit Jupiter's outer moons - safe from it's radiation belts. Extra points once SpaceX adds plasma propulsion to it (bet on it. ) Unobscured Vision and SALSN 2 Share Link to comment Share on other sites More sharing options...
Unobscured Vision Posted February 10, 2018 Share Posted February 10, 2018 Yep. Look for FH to be a transitory vehicle, at best. And it's not really gonna be in service that long, either. BFS is going to completely overshadow it, and soon. As in "we could launch it this year on Heavy, or delay two years, give you a massive discount, and launch on BFS.". THAT is how soon BFS is going to be doing stuff. It's a SSTO platform in of itself, and it's gonna put OldSpace out of business if they don't change everything. Link to comment Share on other sites More sharing options...
DocM Posted February 11, 2018 Author Share Posted February 11, 2018 (edited) Via Reddit, a comparison of the most recent pre-launch FH animation and (mostly) reality Steven P., +E.Worm Jimmy and Unobscured Vision 3 Share Link to comment Share on other sites More sharing options...
Skiver Veteran Posted February 11, 2018 Veteran Share Posted February 11, 2018 On 10/02/2018 at 7:38 AM, SALSN said: The falcon 9 could have taken the car to GTO, but it did not just go to GTO it's orbit is going almost all the way to the asteroid belt. So yes, the FH could have taken up a lot more, but it would not have gone as far. Not sure if it might have been better, test wise, to load up as much weight as possible to test that capability, but this mission was surely much more interesting :-) Did Falcon Heavy take it much further than GTO? I thought Falcon Heavy took it to around GTO and then the second stage is responsible for the rest? Link to comment Share on other sites More sharing options...
Jim K Global Moderator Posted February 11, 2018 Global Moderator Share Posted February 11, 2018 36 minutes ago, Skiver said: Did Falcon Heavy take it much further than GTO? I thought Falcon Heavy took it to around GTO and then the second stage is responsible for the rest? Ignore the car as a "capability" ... remember the FH is the entire stack (first/second stage). FH can take 140K pounds to LEO, 58K pounds to GTO, 37K pounds to Mars and almost 8K pounds to Pluto. But yea, on simpler terms, the first stage is responsible for the "heavy lift" ... punching it through the denser atmosphere while the second stage is responsible for insertion into whatever trajectory is needed (GTO, Mars, etc) .... plus whatever booster is on the payload. SALSN, bguy_1986, Unobscured Vision and 1 other 4 Share Link to comment Share on other sites More sharing options...
Skiver Veteran Posted February 12, 2018 Veteran Share Posted February 12, 2018 17 hours ago, Jim K said: Ignore the car as a "capability" ... remember the FH is the entire stack (first/second stage). FH can take 140K pounds to LEO, 58K pounds to GTO, 37K pounds to Mars and almost 8K pounds to Pluto. But yea, on simpler terms, the first stage is responsible for the "heavy lift" ... punching it through the denser atmosphere while the second stage is responsible for insertion into whatever trajectory is needed (GTO, Mars, etc) .... plus whatever booster is on the payload. Silly me of course! The side boosters are classed as stage 1, the centre core is stage 2 with the (not sure if it has a name) last stage being the single Merlin engine that did the 6 hour coast and then final burn off to Mars/Ceres. Link to comment Share on other sites More sharing options...
SALSN Posted February 12, 2018 Share Posted February 12, 2018 5 hours ago, Skiver said: Silly me of course! The side boosters are classed as stage 1, the centre core is stage 2 with the (not sure if it has a name) last stage being the single Merlin engine that did the 6 hour coast and then final burn off to Mars/Ceres. All the stages are part of the Falcon Heavy rocket, and as far as I can tell, only the upper stage (which I would call the second stage) reaches orbital velocity. Of course it is similar, perhaps even entirely identical, to the F9 upper stage, but with the three cores beneath, it is the FH second stage :-) Link to comment Share on other sites More sharing options...
DocM Posted February 12, 2018 Author Share Posted February 12, 2018 FH's upper stage is different than previous upper stages, described as a "Frankenstage" because it has to fly heavier payloads and there's also the "Long Coast" mission kit for direct injection into geostationary orbits. The same is true of the center core - beefed up on the production line handle increased loads from heavier payloads and the boosters. Some of these changes will carry over into the new Block 5 cores, but odds are there will still be "mission kits" added to Falcon Heavy center cores and upper stages. Unobscured Vision and SALSN 2 Share Link to comment Share on other sites More sharing options...
Jim K Global Moderator Posted March 11, 2018 Global Moderator Share Posted March 11, 2018 Pretty neat video. Shows the center core taking the splash at 1:12 Unobscured Vision 1 Share Link to comment Share on other sites More sharing options...
DocM Posted March 11, 2018 Author Share Posted March 11, 2018 Produced by Jonathan Nolan; writer for Interstellar, Batman Begins/Dark Knight, Westworld. Director Christopher Nolan's brother. Unobscured Vision 1 Share Link to comment Share on other sites More sharing options...
DocM Posted August 29, 2018 Author Share Posted August 29, 2018 Sends a chill, and a thrill, every.damned.time ? Unobscured Vision 1 Share Link to comment Share on other sites More sharing options...
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