True, but today we don't need to use film, we have the capability to broadcast, receive, and store HD quality video using tiny devices. Then you don't have to hope that any magic box survives in order to tell you what went wrong.
Back in the bad old days when we actually had the capability to land men on the moon, telemetry meant that you collected the signals you needed, and downlinked them. They were then recorded.I know that we live in a brave new digital world, but everyone wanting to build some super duper flight recorder for the F9 first stage is mucking it up, in my opinion. Unnecessarily complicated, unnecessarily rugged.Do the same thing that the OGBs did- perhaps as simple as a couple of rocket cams to watch what happens and a simple transmitter spewing TLM for a ground station to record.
Quote from: Robotbeat on 12/30/2010 03:03 pmQuote from: Lee Jay on 12/30/2010 02:02 amQuote from: Nomadd on 12/30/2010 12:18 am 2 bytes of data gives you 64k analog resolution, so 1,000 samples per second would only be around 120KB raw data per minute if you had some nice clean software that only stored results. Been in this discussion with airliner folks who were convinced that you couldn't send real time system monitoring without using "Huge" amounts of bandwidth. You can pack a pretty impressive number of high resolution/rate analog readings into a small data stream if you're old enough to remember when efficiency counted and you didn't get to use 4 thousand lines of code to read a switch.Now, imagine you have 70 such channels plus a couple of tri-axial accelerometers you want to sample at 20kHz. On each engine. And you have another hundred or so channels on the stage and FTS. And you have a similar situation on the upper stage, just with one engine. I make that at over 1.5GB/s.It can add up when you have a few high-rate channels and when you have hundreds and hundreds of channels.No, you're wrong.You skipped two zeros.It'd be 15MB/s based on what you just said.((70*1000Hz+2*3*20000Hz)*9+300*20000Hz)*2Bytes = ~15MB/s(you can easily check this in Google if you wish)...(since you used "120KB raw data per minute")...
Quote from: Lee Jay on 12/30/2010 02:02 amQuote from: Nomadd on 12/30/2010 12:18 am 2 bytes of data gives you 64k analog resolution, so 1,000 samples per second would only be around 120KB raw data per minute if you had some nice clean software that only stored results. Been in this discussion with airliner folks who were convinced that you couldn't send real time system monitoring without using "Huge" amounts of bandwidth. You can pack a pretty impressive number of high resolution/rate analog readings into a small data stream if you're old enough to remember when efficiency counted and you didn't get to use 4 thousand lines of code to read a switch.Now, imagine you have 70 such channels plus a couple of tri-axial accelerometers you want to sample at 20kHz. On each engine. And you have another hundred or so channels on the stage and FTS. And you have a similar situation on the upper stage, just with one engine. I make that at over 1.5GB/s.It can add up when you have a few high-rate channels and when you have hundreds and hundreds of channels.No, you're wrong.You skipped two zeros.It'd be 15MB/s based on what you just said.((70*1000Hz+2*3*20000Hz)*9+300*20000Hz)*2Bytes = ~15MB/s(you can easily check this in Google if you wish)
Quote from: Nomadd on 12/30/2010 12:18 am 2 bytes of data gives you 64k analog resolution, so 1,000 samples per second would only be around 120KB raw data per minute if you had some nice clean software that only stored results. Been in this discussion with airliner folks who were convinced that you couldn't send real time system monitoring without using "Huge" amounts of bandwidth. You can pack a pretty impressive number of high resolution/rate analog readings into a small data stream if you're old enough to remember when efficiency counted and you didn't get to use 4 thousand lines of code to read a switch.Now, imagine you have 70 such channels plus a couple of tri-axial accelerometers you want to sample at 20kHz. On each engine. And you have another hundred or so channels on the stage and FTS. And you have a similar situation on the upper stage, just with one engine. I make that at over 1.5GB/s.It can add up when you have a few high-rate channels and when you have hundreds and hundreds of channels.
2 bytes of data gives you 64k analog resolution, so 1,000 samples per second would only be around 120KB raw data per minute if you had some nice clean software that only stored results. Been in this discussion with airliner folks who were convinced that you couldn't send real time system monitoring without using "Huge" amounts of bandwidth. You can pack a pretty impressive number of high resolution/rate analog readings into a small data stream if you're old enough to remember when efficiency counted and you didn't get to use 4 thousand lines of code to read a switch.
Yes, you could store it on a UDMA Compact Flash card for the whole ascent. I wouldn't want to try to find it in the ocean, however.
{snip}Yes, you could store it on a UDMA Compact Flash card for the whole ascent. I wouldn't want to try to find it in the ocean, however.
I thought the dragon page said they were on good ol' Mil Std 1553 and RS-422 also?
Quote from: TexasRED on 12/30/2010 07:29 pmI thought the dragon page said they were on good ol' Mil Std 1553 and RS-422 also?Those are onboard data buses, not telemetered/RF formats.
Press release from DLA Energy about the recent flight:http://www.dla.mil/DLAPublic/DLA_Media_Center/PressRelease/PressReleasePrintable.aspx?ID=909they were apparently the provider of the hypergolic fuels, and also provided logistics for recovery (presumably unused fuel cleanup / mitigation)
Liquid Oxygen at $95/TN? I'm assuming that "TN" doesn't mean "ton" or else LOX costs less than concrete, which would be a bit shocking. Can someone help me out here?
LOx is made from air.
Quote from: Robotbeat on 01/04/2011 04:43 pmLOx is made from air.Do they use a centrifuge then? I would have thought they would do electrolyis of water. Either way, the price is probably mostly from the energy required to separate, chill, and truck it.
Quote from: Lee Jay on 01/04/2011 04:32 pmLiquid Oxygen at $95/TN? I'm assuming that "TN" doesn't mean "ton" or else LOX costs less than concrete, which would be a bit shocking. Can someone help me out here?LOx is incredibly cheap. LOx is made from air.
Quote from: Robotbeat on 01/04/2011 04:43 pmQuote from: Lee Jay on 01/04/2011 04:32 pmLiquid Oxygen at $95/TN? I'm assuming that "TN" doesn't mean "ton" or else LOX costs less than concrete, which would be a bit shocking. Can someone help me out here?LOx is incredibly cheap. LOx is made from air. And huge amounts of energy and a large cryogenic plant. Is it really $95 a ton?
Quote from: starsilk on 01/04/2011 03:16 pmPress release from DLA Energy about the recent flight:http://www.dla.mil/DLAPublic/DLA_Media_Center/PressRelease/PressReleasePrintable.aspx?ID=909they were apparently the provider of the hypergolic fuels, and also provided logistics for recovery (presumably unused fuel cleanup / mitigation)CuriousDLA (which has a .MIL domain) provided "two propellants for the historic launch: dinitrogen tetroxide and monomethylhydrazine". Once would conclude that SpaceX obtained their LOX and RP-1 from another source, despite DLA Energy being a provider of those at KSC.
Powered by propellants procured by Defense Logistics Agency Energy, a Falcon 9 rocket carries a SpaceX Dragon spacecraft into orbit Dec. 8 from Cape Canaveral Air Force Station, Fla. Photo courtesy of SpaceX