This is TERRIFIC!Such an educationThe first stage landings have stopped getting faster. CRS-11 first stage landed at 7:40 elapsed time. CRS-12 was 6 seconds slower. CRS9 and CRS-10 were identically 40 seconds slower and CRS-8, going to the ASDS was a full 60 seconds slower. But they were all exciting to watch, especially together.There is even more contrast in the first stage flights, with CRS-1 taking way longer to stage. Yet CRS-5 was the shortest time to separation of Dragon. Then there are the LOX-cam views. I miss those.Again, a really cool compilation.
Do have to keep in mind the reason for the longer staging of CRS-1 was due to compensating for the loss of an engine during ascent so stage 1 did burn longer then planned.
Quote from: quagmire on 08/17/2017 05:08 pmDo have to keep in mind the reason for the longer staging of CRS-1 was due to compensating for the loss of an engine during ascent so stage 1 did burn longer then planned. That's not all. IIRC, one of the changes to the Falcon 9 1.1+ design was to reduce the first stage portion of the flight relative to the second stage portion so as to make recovery of the first stage easier.
We can estimate the liftoff thrust from the videos.At the turn of the clock from 6 to 7, it's going 53 km/hr on CR-11 and 51 km/hr on CRS-12. Assume 52 km/hr which is 14.44 m/s. Over 7 seconds this is 2.06 m/s^2.Next we need the mass. From this Environmental Impact Statement we know the Falcon Full Thrust first stage has about 420 tonnes of fuel. It's known to mass about 30 tonnes, plus Musk has stated the first stage can push 125 tonnes. So a total of 575 tonnes at liftoff.So now takeoff thrust is 575,000 * (9.8 + 2.06) = 6.82 MN = 1.53 million pounds force. That's exactly the takeoff thrust quoted in the Environmental Impact above, so it's consistent.So we have definitely not seen the 1.7 million pounds-force version yet.
May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust.
Quote from: LouScheffer on 08/17/2017 07:02 pmWe can estimate the liftoff thrust from the videos.At the turn of the clock from 6 to 7, it's going 53 km/hr on CR-11 and 51 km/hr on CRS-12. Assume 52 km/hr which is 14.44 m/s. Over 7 seconds this is 2.06 m/s^2.Next we need the mass. From this Environmental Impact Statement we know the Falcon Full Thrust first stage has about 420 tonnes of fuel. It's known to mass about 30 tonnes, plus Musk has stated the first stage can push 125 tonnes. So a total of 575 tonnes at liftoff.So now takeoff thrust is 575,000 * (9.8 + 2.06) = 6.82 MN = 1.53 million pounds force. That's exactly the takeoff thrust quoted in the Environmental Impact above, so it's consistent.So we have definitely not seen the 1.7 million pounds-force version yet.Nice analysis. May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust.
Quote from: deruch on 08/18/2017 07:02 am May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust. You don't fly higher-thrust engines for the first time if you do not intend to utilize that higher thrust.
Quote from: woods170 on 08/18/2017 01:07 pmQuote from: deruch on 08/18/2017 07:02 am May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust. You don't fly higher-thrust engines for the first time if you do not intend to utilize that higher thrust.This is not obvious to me. At some point you start qualifying your engines to a new, higher, maximum thrust. You incorporate the new engines into new boosters as they are built. Now suppose the first mission for the new booster does not require the new maximum thrust. What are you going to do? Use the new maximum thrust just because you can? That seems wrong, running at higher ratings surely increases the risk. Swap if for a booster with crappier engines? That seems wrong too.I believe the Shuttle had engine settings which were developed, and qualified, but never intended to be used. They were reserved for abort scenarios.
Quote from: old_sellsword on 08/10/2017 07:02 pmQuote from: First Mate Rummey on 08/10/2017 03:51 pmIs this a block 4 F9? If so what are the improvements vs B3?This is the first Block 4 first stage. Block 4 second stages have been flying for some time now.We’ve heard about thrust upgrades and things like bolted octawebs, but nothing super concrete. It’s basically just a bunch of small hardware upgrades they threw together on their way up to Block 5. We probably wouldn’t even notice the upgrade, especially considering we didn’t notice the Block 2 and 3 upgrades.you will notice some of the block 4 differences if you have a good eye and watch the flight footage and not all are small differences but most are. I'll leave you with that until launch day.
Quote from: First Mate Rummey on 08/10/2017 03:51 pmIs this a block 4 F9? If so what are the improvements vs B3?This is the first Block 4 first stage. Block 4 second stages have been flying for some time now.We’ve heard about thrust upgrades and things like bolted octawebs, but nothing super concrete. It’s basically just a bunch of small hardware upgrades they threw together on their way up to Block 5. We probably wouldn’t even notice the upgrade, especially considering we didn’t notice the Block 2 and 3 upgrades.
Is this a block 4 F9? If so what are the improvements vs B3?
Every time SpaceX introduced more powerfull engines on their rockets they immediately made use of the increased power. There is no valid reason not to do so.
Looks like it is coming down real slow.
Quote from: LouScheffer on 08/18/2017 01:28 pmQuote from: woods170 on 08/18/2017 01:07 pmQuote from: deruch on 08/18/2017 07:02 am May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust. You don't fly higher-thrust engines for the first time if you do not intend to utilize that higher thrust.This is not obvious to me. At some point you start qualifying your engines to a new, higher, maximum thrust. You incorporate the new engines into new boosters as they are built. Now suppose the first mission for the new booster does not require the new maximum thrust. What are you going to do? Use the new maximum thrust just because you can? That seems wrong, running at higher ratings surely increases the risk. Swap if for a booster with crappier engines? That seems wrong too.I believe the Shuttle had engine settings which were developed, and qualified, but never intended to be used. They were reserved for abort scenarios.Every time SpaceX introduced more powerfull engines on their rockets they immediately made use of the increased power. There is no valid reason not to do so.
Quote from: woods170 on 08/18/2017 02:15 pmEvery time SpaceX introduced more powerfull engines on their rockets they immediately made use of the increased power. There is no valid reason not to do so.There's always a first time. And it's quite likely NASA wouldn't want to be the first mission to use higher thrust levels. It seems to me the most plausible explanation for both a) this being the first "block 4" booster with uprated engines and b) seeing a profile consistent with previous boosters.
Quote from: woods170 on 08/18/2017 02:15 pmQuote from: LouScheffer on 08/18/2017 01:28 pmQuote from: woods170 on 08/18/2017 01:07 pmQuote from: deruch on 08/18/2017 07:02 am May have been the 1.7Mlb-f version just flown below the new maximum thrust level though. Not necessarily inconsistent to have info saying that CRS-12 flew with up-rated engines and data showing that the launch didn't, assuming the higher maximum, use full thrust. You don't fly higher-thrust engines for the first time if you do not intend to utilize that higher thrust.This is not obvious to me. At some point you start qualifying your engines to a new, higher, maximum thrust. You incorporate the new engines into new boosters as they are built. Now suppose the first mission for the new booster does not require the new maximum thrust. What are you going to do? Use the new maximum thrust just because you can? That seems wrong, running at higher ratings surely increases the risk. Swap if for a booster with crappier engines? That seems wrong too.I believe the Shuttle had engine settings which were developed, and qualified, but never intended to be used. They were reserved for abort scenarios.Every time SpaceX introduced more powerfull engines on their rockets they immediately made use of the increased power. There is no valid reason not to do so.Higher thrust = increased engine wear = increased refurbishment time + cost. If the performance isn't needed on this mission, why stress the engines more than necessary? Wouldn't you rather reduce the time and cost of refurbishment and possibly extend the booster lifetime?
Not the track record so far... CRS flights have been incredibly supportive of the changes and development efforts. The folks over at Commercial crew should watch and learn.
Quote from: AncientU on 08/18/2017 08:32 pmNot the track record so far... CRS flights have been incredibly supportive of the changes and development efforts. The folks over at Commercial crew should watch and learn.IIRC NASA has previously requested, maybe more than once, not to be the first flight after a big change. For example F9 1.1, RTF after CRS-7, RTF after Amos-6, first flight using new load procedure with sub-cooled prop. None of these were CRS flights. They're also sluggish on getting on-board with using a previously flown booster. Not that any of that is bad, but they are definitely not first adopters when it comes to CRS (COTS was a different matter).The folks at Commercial Crew are, I think, just fine...
We'll see on reused boosters... if NASA accepts a flight-proven booster for CRS within the first year they are flying, that will be incredibly supportive from an organization that nominally works in decades.