-
#300
by
Kaputnik
on 27 Jun, 2017 08:34
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
It seems very likely that SpaceX could easily solve the video dropout problem, if they thought it was actually a problem.
-
#301
by
ugordan
on 27 Jun, 2017 08:37
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
Then again, fishing boats usually rock slowly in the waves and their antennas don't have to cope with plume impingement from a rocket engine and resulting thrashing and vibrations at tens to hundreds of Hz frequency...
-
#302
by
JamesH65
on 27 Jun, 2017 09:55
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
It seems very likely that SpaceX could easily solve the video dropout problem, if they thought it was actually a problem.
If they could fix it really easily, don't you think they would have already done it? They already spend quite a few $ getting that feed to where it is, even though it's really only of use to us, the viewers, if it really was an easy fix, it would be cheap, and probably already done.
-
#303
by
kevin-rf
on 27 Jun, 2017 10:11
-
-
#304
by
cscott
on 27 Jun, 2017 13:23
-
Also, RP1 + LOX produces ionized gas - is this true?
High temperature + any gas = plasma (ionized gas)
"Electrons are free, the fourth state of matter, not solid, liquid, or gas" ... to quote an excellent song.
The RP1 and LOX have little to do with it.
-
#305
by
Nomadd
on 27 Jun, 2017 15:25
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
Then again, fishing boats usually rock slowly in the waves and their antennas don't have to cope with plume impingement from a rocket engine and resulting thrashing and vibrations at tens to hundreds of Hz frequency...
Fishing boats move a helluva a lot more than that barge does. Plume impingement should be handled by having two dishes on opposite ends of the barge and picking a satellite that's not too vertical, or two different sats. I'm not sure what arrangements SpaceX has, but ships almost always have a few different satellites available because the dishes are hardly ever without an obstruction in some direction. You can program in obstructions like masts or superstructures and the controller will know not to try and acquire a blocked sat. If they know what direction the rocket will come in from, they could just program it and the plume as obstructions, or just manually pick a sat that won't be blocked.
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
It seems very likely that SpaceX could easily solve the video dropout problem, if they thought it was actually a problem.
If they could fix it really easily, don't you think they would have already done it? They already spend quite a few $ getting that feed to where it is, even though it's really only of use to us, the viewers, if it really was an easy fix, it would be cheap, and probably already done.
Those big Ku band dishes pretty much stay on target by being perfectly balanced. Tiny stepper motors keep them centered, but even unpowered, the dish stays stays pointing the same way for a while as the boat moves around.
I'm still trying to find out if the vibration problem is through the mount or causes trouble directly through the dome.
-
#306
by
Jim
on 27 Jun, 2017 15:50
-
AFAIK this is unique to SpaceX. This is a very clever solution to a problem unique to SpaceX. Most separations just drift away, and because saving the booster is not an issue, the second stage can fire as soon as it is clear and they don't care if the first stage gets burnt or damaged. SpaceX wants a good distance before the second stage fires and they also want to get this distance very quickly so they can rotate the first stage for the boost back burn. The pusher imparts some momentum to the second stage while slowing down the first stage a little. I know this is small potatoes, but I wonder if that little extra acceleration to the second stage is enough to compensate for the extra fuel used to carry the mass of the pusher mechanism.
Wrong takeaway and not a unique problem to SpaceX. The longer pusher rod is to ensure clearance of the MVac engine bell during staging and not for extra impulse for booster separation. The push rod makes sure that the engine/second stage stays centered while clearing the interstage.
-
#307
by
manoweb
on 27 Jun, 2017 18:04
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
Then again, fishing boats usually rock slowly in the waves and their antennas don't have to cope with plume impingement from a rocket engine and resulting thrashing and vibrations at tens to hundreds of Hz frequency...
No wait, you did not understand. The barge would have a non- or loosely directional antenna to transmit to a nerby boat, and that would have a satellite link. However, there is probably a simple explanation they are not doing it, and it is NOT that they cannot engineer one.
-
#308
by
Jcc
on 28 Jun, 2017 00:07
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
Then again, fishing boats usually rock slowly in the waves and their antennas don't have to cope with plume impingement from a rocket engine and resulting thrashing and vibrations at tens to hundreds of Hz frequency...
No wait, you did not understand. The barge would have a non- or loosely directional antenna to transmit to a nerby boat, and that would have a satellite link. However, there is probably a simple explanation they are not doing it, and it is NOT that they cannot engineer one.
That explanation is that is not important enough a priority. They will have full quality video at multiple angles from the recordings. Telemetry tells them if the stage landed intact in near real time. There is no operational reason why they need perfect realtime video. Even for us spectators it adds to the drama if it cuts off briefly, and we anticipate the recordings like kids on Christmas Eve. Great fun!
-
#309
by
cscott
on 28 Jun, 2017 05:13
-
Those big Ku band dishes pretty much stay on target by being perfectly balanced. Tiny stepper motors keep them centered, but even unpowered, the dish stays stays pointing the same way for a while as the boat moves around.
I'm still trying to find out if the vibration problem is through the mount or causes trouble directly through the dome.
I suspect the problem is not the low frequency heaving, but rather the high frequency high amplitude components: it is unusual for these sorts of vibrations to be coupled into the tracker, since usually a large boat is a quite good low-pass filter.
-
#310
by
envy887
on 28 Jun, 2017 12:11
-
Gimballed self levelling platforms are totally standard OTS equipment. That's how fishing boats can pick up Sky TV.
Then again, fishing boats usually rock slowly in the waves and their antennas don't have to cope with plume impingement from a rocket engine and resulting thrashing and vibrations at tens to hundreds of Hz frequency...
No wait, you did not understand. The barge would have a non- or loosely directional antenna to transmit to a nerby boat, and that would have a satellite link. However, there is probably a simple explanation they are not doing it, and it is NOT that they cannot engineer one.
That explanation is that is not important enough a priority. They will have full quality video at multiple angles from the recordings. Telemetry tells them if the stage landed intact in near real time. There is no operational reason why they need perfect realtime video. Even for us spectators it adds to the drama if it cuts off briefly, and we anticipate the recordings like kids on Christmas Eve. Great fun!
How are they getting live telemetry at landing? Does the booster have a satcom link? Or are the support ships relaying it?
-
#311
by
Nomadd
on 28 Jun, 2017 15:47
-
How are they getting live telemetry at landing? Does the booster have a satcom link? Or are the support ships relaying it?
Telemetry is mostly transmitted to ground stations. The only satcom I know of is Iridium radios, which can do 128k and would be good for selected results if not raw data. But it looks like Iridium might only be for GPS data.
Maybe Iridium will give them free bandwidth once the new system is up.
This is from the F9 user's guide.
-
#312
by
gongora
on 29 Jun, 2017 02:17
-
Reddit user FellowHumanBean noticed an amendment to the FCC launch license for Bulgariasat:
SpaceX BulgariaSat liability insurance
I missed this at the time, but on June 16, the FAA modified SpaceX's liability insurance see LLS 17-101 for the BulgariaSat mission to $68MM, while other missions covered by the same license remain at $30MM.
-
#313
by
intrepidpursuit
on 29 Jun, 2017 15:37
-
Have we seen the final orbit yet? I'm still trying to figure out why this was a tough landing. It was a very light bird for GTO so unless it went to a really high energy orbit then the hard reentry was purposeful testing. Even so, seems like that upper stage probably had a lot of energy left.
-
#314
by
Jarnis
on 29 Jun, 2017 15:45
-
Have we seen the final orbit yet? I'm still trying to figure out why this was a tough landing. It was a very light bird for GTO so unless it went to a really high energy orbit then the hard reentry was purposeful testing. Even so, seems like that upper stage probably had a lot of energy left.
Yes. It was over 60 000km apogee, very super-synch.
-
#315
by
clegg78
on 29 Jun, 2017 15:51
-
Edit - sorry wrong rocket
Damn spaceX and their rapid cadence its easy to get the landings mixed up.
-
#316
by
joncz
on 29 Jun, 2017 19:19
-
Reddit user FellowHumanBean noticed an amendment to the FCC launch license for Bulgariasat:
SpaceX BulgariaSat liability insurance
I missed this at the time, but on June 16, the FAA modified SpaceX's liability insurance see LLS 17-101 for the BulgariaSat mission to $68MM, while other missions covered by the same license remain at $30MM.
I think FellowHumanBean is reading backward and without context.
LLS 17-100, issued in February, required SpaceX to carry $160M in liability insurance
LLS 17-101, issued in March, requires SpaceX to carry $68M liability insurance for BulgariaSat-1 and $30M for subsequent launches.
-
#317
by
gongora
on 29 Jun, 2017 19:42
-
Reddit user FellowHumanBean noticed an amendment to the FCC launch license for Bulgariasat:
SpaceX BulgariaSat liability insurance
I missed this at the time, but on June 16, the FAA modified SpaceX's liability insurance see LLS 17-101 for the BulgariaSat mission to $68MM, while other missions covered by the same license remain at $30MM.
I think FellowHumanBean is reading backward and without context.
LLS 17-100, issued in February, required SpaceX to carry $160M in liability insurance
LLS 17-101, issued in March, requires SpaceX to carry $68M liability insurance for BulgariaSat-1 and $30M for subsequent launches.
LLS 17-100 and LLS 17-101 are licenses for different things. LLS 17-101 (GTO launches) was issued in March, and then updated in June to specifically mention a different insurance rate for Bulgariasat. Other payloads already launched under LLS 17-101 before that update.
-
#318
by
Lars-J
on 30 Jun, 2017 17:36
-
For those of you that have not seen it, here are some pictures showing how far this flight pushed the aluminum grid fins... Very close to failure: (Elon was not kidding)
https://imgur.com/a/WeILL
-
#319
by
Chris_Pi
on 30 Jun, 2017 19:12
-
Looks like they've figured out just what the aluminum fins will put up with. And almost found out if the stage can tolerate losing a fin midflight.
Damn spaceX and their rapid cadence its easy to get the landings mixed up.