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#1780 by whitelancer64 on 23 Dec, 2015 20:51
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The shuttle booms could be heard 100+ miles away, depending on the entry path I could hear these growing up in South Florida. On Monday night we heard 3, about 8 miles from the pad on SR-3 just outside the KSC gates.
Just as a personal testament to this, I once heard the double sonic boom of the incoming Shuttle from about 90 miles away; one summer I was with my family at Lake Perris, CA, and we heard a boom, boom, that waS from (I think) STS-117. I knew immediately what it was, it was a pretty cool thing to hear. -
#1781 by AJW on 23 Dec, 2015 20:52
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That all said... is it really important? Does anyone think that the soot will do anything, other than make them spend a little more effort cleaning the stage? (Honest question here).
That's a good question.
To me, the significance of the soot is the implication that something unexpected (to us) was happening on or around the stage during its decent through the atmosphere. Depending on what is the root cause, it could have implications for performance or reliability. For example - is it (as some have speculated) a chilling effect from the LOX? Therefore does it indicate a flaw in the tank insulation or an indication of ice build-up during flight? Build up of frost could lead to issues like changes in the centre of gravity or asymmetric drag during the free-fall descent phase in between MECO3 and MES4.
I can't confirm, but asked a friend who dismissed the issue and said that he believes that a different paint is used beneath the SpaceX logo. -
#1782 by AJW on 23 Dec, 2015 20:58
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The shuttle booms could be heard 100+ miles away, depending on the entry path I could hear these growing up in South Florida. On Monday night we heard 3, about 8 miles from the pad on SR-3 just outside the KSC gates.
Just as a personal testament to this, I once heard the double sonic boom of the incoming Shuttle from about 90 miles away; one summer I was with my family at Lake Perris, CA, and we heard a boom, boom, that waS from (I think) STS-117. I knew immediately what it was, it was a pretty cool thing to hear.
There was a night Shuttle landing that travelled over Northern California. I took my son out in his sleeping bag and we watched the beautiful arc travel across the sky. We stayed outside as it faded and later while walking down the hallway putting my son to bed, the hallway door did a brief shutter. I didn't have a watch, but I would say it was 8-10 minutes after the Shuttle first appeared. -
#1783 by cebri on 23 Dec, 2015 21:39
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I've been searching but i don't know if this has been posted.
Elon's conference after the mission.
Edit: LOL, it was in the previous page, i don't know how i didn't see it.
Edit2: Mine is a "dewinded" version. -
#1784 by Antilope7724 on 23 Dec, 2015 22:14
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That all said... is it really important? Does anyone think that the soot will do anything, other than make them spend a little more effort cleaning the stage? (Honest question here).
That's a good question.
To me, the significance of the soot is the implication that something unexpected (to us) was happening on or around the stage during its decent through the atmosphere. Depending on what is the root cause, it could have implications for performance or reliability. For example - is it (as some have speculated) a chilling effect from the LOX? Therefore does it indicate a flaw in the tank insulation or an indication of ice build-up during flight? Build up of frost could lead to issues like changes in the centre of gravity or asymmetric drag during the free-fall descent phase in between MECO3 and MES4.
With all of that soot coming out of the engines, what does that say about reuse-ability of the engines without the necessity of a teardown for internal cleaning? Are the internals of the engines being clogged by this condition? -
#1785 by Lee Jay on 23 Dec, 2015 22:16
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With all of that soot coming out of the engines, what does that say about reuse-ability of the engines without the necessity of a teardown for internal cleaning? Are the internals of the engines being clogged by this condition?
You can clean the engine internals without disassembly. They can be flushed with solvent, for example. -
#1786 by inonepiece on 23 Dec, 2015 22:22
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Elon's conference after the mission.
Edit: LOL, it was in the previous page, i don't know how i didn't see it.
Edit2: Mine is a "dewinded" version.
Thanks! On the other hand, now I can see why only the transcripts were posted! (terrible audio, not cebri's fault of course, it's just down to Elon wandering about at LZ1 on a windy day while he talked)
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#1787 by Lars-J on 23 Dec, 2015 22:22
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With all of that soot coming out of the engines, what does that say about reuse-ability of the engines without the necessity of a teardown for internal cleaning? Are the internals of the engines being clogged by this condition?
This is something they can easily test on a test stand by pushing an M1D to the limit as far as runtime and restart count, and I'm sure they have done so.
That is the *least* of my concerns for reusability. -
#1788 by edkyle99 on 23 Dec, 2015 22:26
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The shuttle booms could be heard 100+ miles away, depending on the entry path I could hear these growing up in South Florida. On Monday night we heard 3, about 8 miles from the pad on SR-3 just outside the KSC gates.
I heard an STS sonic boom once out my open bedroom window in the Chicago area. It was one of the rare missions where the ground track passed over the Chicago area. I knew what it was because I knew the timing of the landing and I had heard the same double-boom prior to seeing a landing in Florida. It wasn't as loud, but it was sharp and distinct.
- Ed Kyle -
#1789 by Lars-J on 23 Dec, 2015 22:29
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F9 boosters come down close to vertical, so they would have a much smaller sonic boom footprint than Shuttle orbiters did. (if I understand things right)
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#1790 by CaptLego on 23 Dec, 2015 23:16
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i have a question so please help. What is that S shaped thing on the big screen in the control room? Its at exactly 34:23 please take a look
I am looking at it and going what view is that, what is it?
If you are referring to this circled area, I'm fairly sure it is the internal tank camera view on the 2nd stage.
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#1791 by Rocket Science on 23 Dec, 2015 23:48
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AAR built the Falcon's legs... Pretty cool!
http://www.roadandtrack.com/motorsports/news/a27716/all-american-racers-spacex/?click=my6sense -
#1792 by CyndyC on 24 Dec, 2015 00:21
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The critical aspect isn't coming up with that 3 burn scheme.
Its having a rocket efficient enough that it has spare DeltaV to do useful work and the 3 burns.
Its designing rocket engines that can endure this cycle at least a half a dozen times with high reliability (SpaceX still needs to prove that).
All of that while not making the rocket way more expensive than regular expendable ones.
There has been so much discussion about the return burns, and now this from macpacheco, but there seems to be little to no credit ever given the 4 grid fins, engineering marvels in themselves, which "improve the accuracy of Falcon's landing by three orders of magnitude," according to Spaceflight 101 at http://spaceflight101.com/spacerockets/falcon-9-ft/.
In case you don't want to go there, here's everything they say, quite interesting:
"The four grid fins are launched in a position stowed against the uppermost section of the first stage near the interstage before being deployed when Falcon 9 re-enters the atmosphere. A slight modification of the grid design is part of the F9 FT upgrade. The four fins can be individually controlled in a two-degree of freedom type design, rotating and tilting at the same time, allowing for complex guidance and control during atmospheric flight.
The fins are an essential part of Falcon’s return sequence to provide control in atmospheric flight without active propulsion. Grid-fins have been widely used as a stabilizer on missiles & bombs and are shaped like miniature wings consisting of a lattice structure. The Russian Soyuz employs grid-fins in its launch abort system which would deploy when the launch escape rockets start firing in an abort scenario to stabilize the vehicle, but the fins used by SpaceX take it one step further as they can be moved independently to actively control the vehicle’s flight and not only act as a stabilizer.
Grid-fins perform well in all velocity ranges including supersonic and subsonic speeds with the exception of the trans-sonic regime due to the shock wave enveloping the grid. These properties make them ideally suitable for the Falcon 9 first stage that starts out at supersonic speeds and returns to subsonic velocity as it travels through the atmosphere, en-route to the landing site. The four fins are rotated and tilted independently by an open hydraulic system using pressurized hydraulic fluid supplied from a pressurized tank that is dumped overboard after flowing through the hydraulic actuators of the fin system. The design was also driven by overall mass considerations.
The addition of the grid fins was expected to improve the accuracy of Falcon’s landing by three orders of magnitude – previous landing attempts in the ocean had a ten-Kilometer targeting accuracy while the return to a platform or a pad on land requires the stage to land within a few meters of its bulls-eye target."
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#1793 by yg1968 on 24 Dec, 2015 00:34
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Elon's conference after the mission.
Edit: LOL, it was in the previous page, i don't know how i didn't see it.
Edit2: Mine is a "dewinded" version.
Thanks! On the other hand, now I can see why only the transcripts were posted! (terrible audio, not cebri's fault of course, it's just down to Elon wandering about at LZ1 on a windy day while he talked)
Do you have a link to the transcript? -
#1794 by Kabloona on 24 Dec, 2015 00:35
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Quote
There has been so much discussion about the return burns, and now this from macpacheco, but there seems to be little to no credit ever given the 4 grid fins, engineering marvels in themselves
Yes, whoever thought of adding grid fins can take a good deal of credit for perfecting the landing system. Maybe Elon himself? -
#1795 by Rocket Science on 24 Dec, 2015 00:40
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Maybe he read my post suggesting them from a few years back!QuoteThere has been so much discussion about the return burns, and now this from macpacheco, but there seems to be little to no credit ever given the 4 grid fins, engineering marvels in themselves
Yes, whoever thought of adding grid fins can take a good deal of credit for perfecting the landing system. Maybe Elon himself?
http://forum.nasaspaceflight.com/index.php?topic=21923.480
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#1796 by CyndyC on 24 Dec, 2015 00:42
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Quote
There has been so much discussion about the return burns, and now this from macpacheco, but there seems to be little to no credit ever given the 4 grid fins, engineering marvels in themselves
Yes, whoever thought of adding grid fins can take a good deal of credit for perfecting the landing system. Maybe Elon himself?
Exactly what I was thinking, Kabloona! -
#1797 by Dave G on 24 Dec, 2015 01:19
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Let's relight this candle. (OK, not this actual candle ...
It looks like SpaceX will relight this actual candle, on LC-39A, within the coming days or weeks.
Also from the post-landing press call, Musk didn't completely rule out re-flying this particular stage.
Here's a transcript from part of the post-landing press call:QuoteSFN: Hi this is Stephen Clark from Spaceflight Now. Can you hear me?
MUSK: Yep.
SFN: Elon, thanks for doing the call. I was just wondering what your plan is for this particluar booster over the coming days and weeks, and do you intend to fly it again? Thanks.
MUSK: Yeah, so the plan is to take the booster over to Launch Complex 39A, you know, the Apollo 11 launch site we are leasing from NASA here at the cape, and do a static fire on the launch pad there. So we'll confirm that all systems are good and that we're able to do a full thrust hold-down firing of the rocket. And then I think we'll probably keep this one on the ground just because it's quite unique - the first one that we brought back. So I think we'll keep this one on the ground and just confirm through tests that it could fly again, and then put it somewhere just to sort of - it's quite unique.
So I think I think we'll end up re-flying one of the subsequent boosters. And we have quite a big flight manifest. We should be doing well over a dozen flights next year. And I think probably before, you know, sometime next year we would aim to re-fly one of the rocket boosters.
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#1798 by macpacheco on 24 Dec, 2015 01:23
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It looks like SpaceX will relight this actual candle, on LC-39A, within the coming days or weeks.
Precisely. Musk is being smart cause he doesn't know what will be the result of that static fire for sure. If they do the static fire without issue, boroscope / x-ray every critical part and find out the stage is good to go (or need a few affordable parts replaced), why not fly it again, but if he says he's going to do it, then he's in a pickle if they find out the stage isn't quite within safety margins.
Also from the post-landing press call, Musk didn't rule out re-flying this particular stage.
Here's a transcript from part of the post-landing press call:
In that case it seems like the stage goes to NM for reflight until exhaustion as a GH2 (or would it be GH3) test article.
Put the HD footage of the first landing (and the 2nd, 3rd, 4th) and the first few reflights on the museum. -
#1799 by QuantumG on 24 Dec, 2015 01:32
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Not sure how you interpret "I think we'll keep this one on the ground and just confirm through tests that it could fly again, and then put it somewhere" as saying anything other than: we won't refly this one. I think it's a waste, but people are sentimental I guess.
