PC12Fan
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RE: SpaceX - Tests, Launches, Developments

Fri May 06, 2016 10:54 pm

Just when I think you've said the stupidest thing ever, you keep talkin'!
 
maxter
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RE: SpaceX - Tests, Launches, Developments

Tue May 10, 2016 9:16 am

https://www.youtube.com/watch?v=LHqLz9ni0Bo
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Francoflier
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RE: SpaceX - Tests, Launches, Developments

Wed May 11, 2016 8:19 am

Quoting maxter (Reply 151):

Awesome.

Is it me or does it seem to slide a few feet to the left after main engine cutoff, at the 42 seconds mark in the video?
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moo
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RE: SpaceX - Tests, Launches, Developments

Wed May 11, 2016 12:21 pm

Quoting Francoflier (Reply 152):
Is it me or does it seem to slide a few feet to the left after main engine cutoff, at the 42 seconds mark in the video?

Looks like there was a "burp" from the engines, giving the vehicle some thrust which allowed either the rolling action of the barge or the wind to shift the vehicle slightly.
 
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Tugger
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RE: SpaceX - Tests, Launches, Developments

Thu May 19, 2016 2:07 pm

Latest from SpaceX on the most recent booster landing, she won't fly again:

Quote:
“Most recent rocket took max damage, due to (very) high entry velocity,” Musk posted on Twitter.

When the rocket’s primary stage separated from the second-stage about 2.5 minutes after liftoff, it was zipping along at 5,220 mph, or about 1.5 miles per second.

After coasting to an altitude 76 miles above Earth, the rocket slammed into the atmosphere at Mach 5.7. With a half-mile left to go, the rocket ignited three of its nine engines to shave its speed from 441 mph to 134 mph in three seconds.

With one engine still burning and running out of fuel, the rocket, now traveling at about 2.5 mph, settled itself onto a platform floating in the Atlantic Ocean east of its Cape Canaveral, Florida, launch site.

The scorched booster likely won’t be flying again.

Instead, it “will be our life leader for ground tests to confirm others are good,” Musk wrote on Twitter.
http://news.discovery.com/space/priv...ket-suffered-max-damage-160518.htm

I love this picture in the article:
http://static.ddmcdn.com/gif/blogs/dnews-files-2016-05-26428480464_13f0002221_k-1024x682-jpg.jpg

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Francoflier
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RE: SpaceX - Tests, Launches, Developments

Thu May 19, 2016 3:44 pm

Quoting Tugger (Reply 154):

Interesting.

I wonder what prevents them from placing the recovery barge a bit farther out to allow the landing stage to lose more energy by drag rather than violently decelerating it with the motors.
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zanl188
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RE: SpaceX - Tests, Launches, Developments

Thu May 19, 2016 7:22 pm

Quoting Francoflier (Reply 155):

I'd guess the additional drag would manifest itself as heat... looks like this booster already pushed its thermal limits pretty hard.
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Oroka
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 12:23 am

maybe not the rocket engines, but im sure alot of the body is still useable if they so desire. not a complete write off.
 
nomadd22
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 1:49 am

Quoting Francoflier (Reply 155):

Interesting.

I wonder what prevents them from placing the recovery barge a bit farther out to allow the landing stage to lose more energy by drag rather than violently decelerating it with the motors.

That drag is what caused the damage, not decelerating with the motors. And half the purpose of the re-entry burn is for the exhaust plume from the engines to act as a shield against the atmosphere during the most violent part of re-entry.
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 5:21 am

Quoting nomadd22 (Reply 158):

I see.
Why not a longer but less intense burn then?
4.5 g sounds like a lot for a relatively frail rocket to endure. But then I'm not sure how tough they built the thing seeing how it's meant to be reusable...
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angad84
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 8:43 am

Quoting Francoflier (Reply 159):
4.5 g sounds like a lot for a relatively frail rocket to endure. But then I'm not sure how tough they built the thing seeing how it's meant to be reusable...

Wouldn't the forces of Max-Q be the strongest endured by the rocket? I have only a layman's knowledge of spaceflight, but by my understanding, if it can survive Max-Q, it can handle anything else - it all comes down to density/speed (drag).

Cheers
A
 
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 1:49 pm

Quoting Francoflier (Reply 159):
But then I'm not sure how tough they built the thing seeing how it's meant to be reusable...

I think reusability was a secondary goal of the Falcon 9. I would expect to see changes made to the design as SpaceX learns where and what on the rocket is having trouble. Also, if fuel is an issue for recovering rockets that are doing higher satellite insertions, they may find a way to improve efficiency of the motors or add more reserve fuel capacity specifically to land the rocket.
 
nomadd22
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RE: SpaceX - Tests, Launches, Developments

Fri May 20, 2016 3:16 pm

Quoting angad84 (Reply 160):

Wouldn't the forces of Max-Q be the strongest endured by the rocket? I have only a layman's knowledge of spaceflight, but by my understanding, if it can survive Max-Q, it can handle anything else - it all comes down to density/speed (drag).

I meant "violent" to include heat. Re-entry isn't as dynamically punishing as max-Q, but the heat and plasma damage is much greater. Less air, but much higher velocity air.

Quoting Francoflier (Reply 159):
I see.
Why not a longer but less intense burn then?
4.5 g sounds like a lot for a relatively frail rocket to endure. But then I'm not sure how tough they built the thing seeing how it's meant to be reusable...

4.5 Gs is easy. Acceleration reaches 5 Gs during launch, and those are much harder on the rocket since it's pushing the 2nd stage and payload. 4.5 Gs on a nearly empty stage is far less force on the rocket.
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angad84
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RE: SpaceX - Tests, Launches, Developments

Sat May 21, 2016 4:15 pm

Quoting nomadd22 (Reply 162):
I meant "violent" to include heat. Re-entry isn't as dynamically punishing as max-Q, but the heat and plasma damage is much greater. Less air, but much higher velocity air.

Understood, although I was responding specifically to francoflier's remarks about g forces and the strength of the rocket.

Quoting nomadd22 (Reply 162):
4.5 Gs is easy. Acceleration reaches 5 Gs during launch, and those are much harder on the rocket since it's pushing the 2nd stage and payload. 4.5 Gs on a nearly empty stage is far less force on the rocket.

Thanks, that's kind of what my intuition as well.

Cheers
A
 
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Francoflier
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RE: SpaceX - Tests, Launches, Developments

Sun May 22, 2016 4:29 pm

Quoting nomadd22 (Reply 162):
I meant "violent" to include heat.


I guess my question is: what causes the most damage during the re-entry and recovery of a Falcon booster?

The re-entry and associated heat, the violent engine burn and its heat, or the mechanical stresses of either/both?

(I understand a shorter but stronger burn for the final deceleration allows to save a bit of fuel)
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travelavnut
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RE: SpaceX - Tests, Launches, Developments

Tue May 24, 2016 12:18 pm

Quoting Oroka (Reply 161):
I think reusability was a secondary goal of the Falcon 9.

It has been a primary goal in the design from day 1.

Quoting Oroka (Reply 161):
Also, if fuel is an issue for recovering rockets that are doing higher satellite insertions, they may find a way to improve efficiency of the motors or add more reserve fuel capacity specifically to land the rocket.

They actually did that during the last two iterations of Falcon 9 in the last 6 months. With the 1.1 version they started with densified propellants and with the Full Thrust version they are only now using the full certified thrust of the Merlin-D.
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Oroka
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RE: SpaceX - Tests, Launches, Developments

Tue May 24, 2016 4:09 pm

Quoting travelavnut (Reply 165):
They actually did that during the last two iterations of Falcon 9 in the last 6 months. With the 1.1 version they started with densified propellants and with the Full Thrust version they are only now using the full certified thrust of the Merlin-D.

Yes, but this latest rocket essentially got ruined because there was not enough fuel to slow it down for re-entry because of the mission profile. If they can have enough fuel to save rockets on such a mission, that means millions more dollars in SpaceX accounts.
 
travelavnut
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RE: SpaceX - Tests, Launches, Developments

Thu May 26, 2016 2:37 pm

Quoting Oroka (Reply 166):

Yes, but this latest rocket essentially got ruined because there was not enough fuel to slow it down for re-entry because of the mission profile.

Well not exactly. It endured max damage, but it's certainly re-flyable according to Musk: https://twitter.com/elonmusk/status/734274360588926976

"@SchaFFFFFF Flight 24 is def capable of flying again, but it makes sense to apply ground delta qual to rocket w toughest entry conditions."

It did not get ruined at all, well maybe slightly. But this core has the most damage any core will have to be able to deal with. Not only was this a highly energetic launch but the payload was also really heavy.

Quoting Oroka (Reply 166):
If they can have enough fuel to save rockets on such a mission, that means millions more dollars in SpaceX accounts.

That they can land this core at all is directly related to the added fuel through densification and there is not much more they can do without heavy redesign.
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RE: SpaceX - Tests, Launches, Developments

Thu May 26, 2016 5:48 pm

I wonder how much more payload they were able to get out of this densified fuel.

I believe the Falcon 9 design sacrifices around 30% of its total payload capability for the sake of landing the first stage.

They essentially sell the 70% as 100% capability, but I wonder if they would accept customers who desire/need the 'real' 100% and just dump the first stage?
I also wonder whether this launch topped out or actually slightly exceeded the rocket's capacity for first stage landing?

Any word on what's being done to the Falcons they've recovered so far?
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Tugger
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RE: SpaceX - Tests, Launches, Developments

Thu May 26, 2016 7:47 pm

Quoting Francoflier (Reply 168):
They essentially sell the 70% as 100% capability, but I wonder if they would accept customers who desire/need the 'real' 100% and just dump the first stage?

The answer to this is "yes", they have mentioned it before. You just pay for it and their goal has been figuring out ways to reduce the cost as much as possible and recovering the stage is a big savings they essentially pass on to the customer.

Tugg
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zanl188
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RE: SpaceX - Tests, Launches, Developments

Thu May 26, 2016 10:15 pm

Quoting Tugger (Reply 169):

Are they planning, long run, to use stages that are at the end of their service lives for such missions?
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zanl188
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RE: SpaceX - Tests, Launches, Developments

Thu May 26, 2016 11:01 pm

Thaicom launch scrubbed for tonight due to upper stage thrust vectoring issue.
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nomadd22
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RE: SpaceX - Tests, Launches, Developments

Fri May 27, 2016 4:23 am

Quoting Francoflier (Reply 168):
I wonder how much more payload they were able to get out of this densified fuel.

I believe the Falcon 9 design sacrifices around 30% of its total payload capability for the sake of landing the first stage.

They essentially sell the 70% as 100% capability, but I wonder if they would accept customers who desire/need the 'real' 100% and just dump the first stage?
I also wonder whether this launch topped out or actually slightly exceeded the rocket's capacity for first stage landing?

Any word on what's being done to the Falcons they've recovered so far?

Right now, everybody pays for an expendable stage. But they publish a price for 5.5 tonnes to GTO and list the ability of the rocket as 8.3 tons to GTO. SpaceX numbers on their website are often out of date and contradictory. It's hoped they'll settle out now that it looks like they're done with major upgrades for a while. Payload high enough that you lose engine out ability might be a factor in price.
It wasn't long ago that people were questioning if SpaceX would ever hit their hoped for 125,000 pounds engine thrust and 12,500 kg to LEO target. Now they're up to 190,000 pounds engine thrust 22,300 kg to LEO. The Merlin has exceeded everybody's expectations.
The recovered 1st stages have had all (Orbcomm) or some (JCSAT) of the engines removed. The CRS-8 stage might fly again, but the Orbcomm stage is for study and will be put on display and the JCSAT stage took too much damage form the high speed re-entry.
Anon
 
zanl188
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RE: SpaceX - Tests, Launches, Developments

Fri May 27, 2016 9:51 pm

Thaicom launch first stage lands successfully on Of Course I Still Love You.
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SeJoWa
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RE: SpaceX - Tests, Launches, Developments

Fri May 27, 2016 9:53 pm

F a n t a s t i c ! Looks like a perfect landing. Now waiting for the second stage relight.

Edit---

There goes, Thaicom 8 satellite deployed, and SpaceX gets paid in full for a successful mission.

[Edited 2016-05-27 15:15:18]
 
zanl188
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RE: SpaceX - Tests, Launches, Developments

Fri May 27, 2016 11:01 pm

Pretty good video from the 1st stage of the reentry burn. Unfortunately I cannot post it -look for it on YouTube...
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maxter
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RE: SpaceX - Tests, Launches, Developments

Sat May 28, 2016 1:44 am

Yes I wait for the day we get an unobsured view all the way back to the drone-ship.
Once again, great job SpaceX
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RE: SpaceX - Tests, Launches, Developments

Sat May 28, 2016 7:50 am

Quoting maxter (Reply 176):
Yes I wait for the day we get an unobsured view all the way back to the drone-ship.

Its sped up but they posted just that from this landing.
https://www.youtube.com/watch?v=4jEz03Z8azc&feature=youtu.be
 
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RE: SpaceX - Tests, Launches, Developments

Sat May 28, 2016 8:42 am

 
SeJoWa
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RE: SpaceX - Tests, Launches, Developments

Sat May 28, 2016 1:04 pm

During the live feed of the first stage's return, transmission of the landing was briefly interrupted.

It basically appeared almost perfectly centered out of nowhere on the raft.

Very interesting to read about the backup shock absorbers, and to learn precisely what the outer limits of this system are.

I'm still boundlessly amazed, and would like to point out that without SpaceX, the USA would in practiCe be excluded from commercial launches.

http://spaceflightnow.com/launch-schedule/

[Edited 2016-05-28 06:06:20]
 
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Francoflier
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RE: SpaceX - Tests, Launches, Developments

Sat May 28, 2016 1:46 pm

I just wish I could find the normal speed footage of the landing from the first stage.
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Tugger
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RE: SpaceX - Tests, Launches, Developments

Sun May 29, 2016 6:02 am

Quoting Francoflier (Reply 180):
I just wish I could find the normal speed footage of the landing from the first stage.

Try this:
http://youtu.be/_uztxi4fE94?t=345

It's the webcast and is in real time.

Tugg
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sf260
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RE: SpaceX - Tests, Launches, Developments

Mon May 30, 2016 8:22 pm

Does anyone know something about how space x is getting with the reusability of the 2nd stage? Any tests announced, or timeline, or technology to be used (I guess it will be some sort of heat shield to slow down)?
 
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Francoflier
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RE: SpaceX - Tests, Launches, Developments

Tue May 31, 2016 1:10 am

Quoting Tugger (Reply 181):

Thanks!

Funny, there's also a few videos on youtube now of the original timelapsed footage slowed back down to normal speed...
The feed from the barge craps out at landing time as the vibration from the landing rocket shakes the satellite antenna out of alignment.
I guess we'll have to wait for the barge to make it back to land and see if Space X releases the recorded footage.

Quoting sf260 (Reply 182):
Does anyone know something about how space x is getting with the reusability of the 2nd stage?

I might be wrong, but I thought they had put this on the back burner as it was technologically too challenging and just too expensive to achieve compared to the price of a second stage.

Since it inserts itself in orbit (or almost) along with the payload, it would need to shed a boatload of energy and make a full reentry in the atmosphere, and you need a whole lot of kit for that.
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nomadd22
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RE: SpaceX - Tests, Launches, Developments

Tue May 31, 2016 1:41 am

Quoting Francoflier (Reply 183):
The feed from the barge craps out at landing time as the vibration from the landing rocket shakes the satellite antenna out of alignment.

Vibration shouldn't have any effect on those antennas. They maintain point by being perfectly balanced, with only tiny tracking motors. The only way movement or vibration lower than damaging level would affect them is if they weren't properly balanced during setup.
Anon
 
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RE: SpaceX - Tests, Launches, Developments

Tue May 31, 2016 2:35 am

Quoting nomadd22 (Reply 184):
Vibration shouldn't have any effect on those antennas.

I actually got that from the real-time launch video feed from Space X on which they always have a couple of engineers commenting on what's going on.
That's what they said would happen right before the first stage showed up on the feed, and the feed went bad right on cue.

I know those marine antennas are automatically stabilized, but while it deals with swells and normal boat motions perfectly, I don't think the system can cope the extreme vibrations caused by a 200ft tall rocket using about 200,000 lbs of thrust from a rocket motor to land on there.

What a thrill it would be to be sitting on that barge when that thing comes in for a landing... behind a heavy blast proof wall.
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RE: SpaceX - Tests, Launches, Developments

Tue May 31, 2016 6:31 pm

Wow, gotta love the ignorance, the willful ignorance of some people:

http://www.youtube.com/watch?v=WLE-ocDoXrs

 Wow!

Actually "love" is the wrong word, "be amazed at" or " be afraid of" or "be terrified by" is more appropriate. This guy is obviously posting from deep inside a preppers bunker etc. and a bit loony but still....

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casinterest
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RE: SpaceX - Tests, Launches, Developments

Wed Jun 01, 2016 3:49 am

Quoting Francoflier (Reply 183):

I might be wrong, but I thought they had put this on the back burner as it was technologically too challenging and just too expensive to achieve compared to the price of a second stage.

Since it inserts itself in orbit (or almost) along with the payload, it would need to shed a boatload of energy and make a full reentry in the atmosphere, and you need a whole lot of kit for that

I found a decent article on the web that discusses a lot about the 2nd stages .

http://space.stackexchange.com/quest...ond-stage-after-payload-separation
this links inside to Elon Musks quotes in 2014

http://shitelonsays.com/transcript/e...-centennial-part-1-of-6-2014-10-24
http://shitelonsays.com/transcript/e...-centennial-part-1-of-6-2014-10-24

"
[What about the second stage?] The next generation vehicles after the Falcon architecture will be designed for full reusability. I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles, which is going to be a -- sub-cooled methane/oxygen system where the propellants are cooled close to their freezing temperature to increase the density, we could definitely do full reusability - and that system is intended to be a fully reusable Mars transportation system. So, not merely to low Earth orbit but all the way to Mars and back, with full reusability. [Within 3 years?] Ha. I am an optimistic person, but - I think we could expect to see some test flights in the five or six year time frame. But, we're talking about a much bigger vehicle, and we're also going to be upgrading to a new generation - a harder engine cycle, which is a full-flow staged combustion. What we have right now is an open cycle engine. Right now, I'd say, engines are our weakest point at SpaceX, but they will become as strong as the structures and avionics in the next generation

"
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David L
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RE: SpaceX - Tests, Launches, Developments

Wed Jun 01, 2016 7:08 am

Quoting Tugger (Reply 186):

   "I don't understand how it's done therefore it can't be done". I mean, how can something that's horizontal become vertical? That's just ridiculous!

  
 
nomadd22
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RE: SpaceX - Tests, Launches, Developments

Fri Jun 03, 2016 4:32 am

Quoting Francoflier (Reply 185):

I know those marine antennas are automatically stabilized, but while it deals with swells and normal boat motions perfectly, I don't think the system can cope the extreme vibrations caused by a 200ft tall rocket using about 200,000 lbs of thrust from a rocket motor to land on there.

I just noticed that SpaceX uses Intellian V110 antennas. I had that model, serial number 1 for testing. We went with Seatels instead because of the unreliability of the Intellian.
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RE: SpaceX - Tests, Launches, Developments

Fri Jun 03, 2016 1:01 pm

Quoting nomadd22 (Reply 184):
Vibration shouldn't have any effect on those antennas. They maintain point by being perfectly balanced, with only tiny tracking motors. The only way movement or vibration lower than damaging level would affect them is if they weren't properly balanced during setup.

The stab of the antennas isn't designed to deal with massive amounts of vibration in all axis at once. I'm sure the amount of moisture and clouding from the rocket exhaust doesn't help the transmissivity much either.
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RE: SpaceX - Tests, Launches, Developments

Fri Jun 03, 2016 2:10 pm

Quoting Tugger (Reply 186):
the willful ignorance of some people:

Hey, shooting rats off the trailer park backyard, following Trump's campaign on Fox News and fooling around with his cousin probably doesn't leave him with enough time to study Newtonian physics...

Quoting casinterest (Reply 187):
So, not merely to low Earth orbit but all the way to Mars and back, with full reusability.

Now that would be something to behold. Can't fault Musk for his lack of vision.
Great links by the way.
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nomadd22
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RE: SpaceX - Tests, Launches, Developments

Fri Jun 03, 2016 2:28 pm

Quoting apfpilot (Reply 190):
The stab of the antennas isn't designed to deal with massive amounts of vibration in all axis at once. I'm sure the amount of moisture and clouding from the rocket exhaust doesn't help the transmissivity much either.

I created a device to measure 4 dimensional (includes frequency) vibration for those antennas. Assuming they're properly balanced, vibration is not going to affect them unless it's severe enough to damage them. It's not an active system that keeps them on target. It's a perfectly balanced dish that doesn't change point as the outer dome moves. I'd be surprised if exhaust did either, since the antennas can work through some pretty severe storms. I might be wrong there.
They have two antennas, but I don't know if they're S and Ku band, identical and redundant or on different sats. Redundant or different sats would be good if you're worried about blockage from the rocket or exhaust. One S band and one Ku band can be good since the different frequencies have different penetration characteristics through clouds and rocket engine exhaust.
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RE: SpaceX - Tests, Launches, Developments

Fri Jun 03, 2016 3:08 pm

Quoting nomadd22 (Reply 192):
I created a device to measure 4 dimensional (includes frequency) vibration for those antennas. Assuming they're properly balanced, vibration is not going to affect them unless it's severe enough to damage them. It's not an active system that keeps them on target. It's a perfectly balanced dish that doesn't change point as the outer dome moves. I'd be surprised if exhaust did either, since the antennas can work through some pretty severe storms. I might be wrong there.

I'd assumed it was an active system, but I can see a passive system making more sense.

Quoting nomadd22 (Reply 192):
They have two antennas, but I don't know if they're S and Ku band, identical and redundant or on different sats. Redundant or different sats would be good if you're worried about blockage from the rocket or exhaust. One S band and one Ku band can be good since the different frequencies have different penetration characteristics through clouds and rocket engine exhaust.

Would an S band have enough bandwidth for live real time streaming of the video? One other potential issue that occurred to me is shadowing of the receiver by the first stage as it descended to the pad.
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nomadd22
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RE: SpaceX - Tests, Launches, Developments

Sat Jun 04, 2016 3:57 am

Quoting apfpilot (Reply 193):

I'd assumed it was an active system, but I can see a passive system making more sense.

They do have small motors that sort of dance a little jig around the sat to constantly finetune the point and, of course, initially acquire or switch sats.

Quoting apfpilot (Reply 193):

Would an S band have enough bandwidth for live real time streaming of the video? One other potential issue that occurred to me is shadowing of the receiver by the first stage as it descended to the pad.

I'm mainly familiar with Inmarsat and MSAT and have been out of the loop for a while. You use to be able to get 600-700 kilobytes, but it was ungodly expensive. Not what you'd want for streaming. I've seen $60,000 monthly bills from ships that forgot to disconnect. It's main advantages were cheaper, easier to point dishes and S-band got through heavy weather better.
My guess would be redundant, hot switched Ku antennas if they were worried about blockage.

[Edited 2016-06-03 21:00:56]
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apfpilot
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Re: SpaceX - Tests, Launches, Developments

Wed Jun 15, 2016 1:58 pm

SpaceX has a launch attempt for a Eutelsat payload coming up this morning: http://www.spacex.com/webcast
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moo
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Re: SpaceX - Tests, Launches, Developments

Wed Jun 15, 2016 3:02 pm

They lost the first stage on landing - it didn't look great when the video feed cut out (lots of nasty black smoke and flames after engine cut off) but it was just confirmed that the first stage was lost. Nothing more yet on how.
 
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Re: SpaceX - Tests, Launches, Developments

Wed Jun 15, 2016 3:32 pm

Too bad it didn't make it but that is why SpaceX is really trying to downplay these landings right now and classifies them as "experimental" etc. They really are just learning and testing and pushing limits to see what is possible. Smart. I wish every one was successful but truth is that just won't be the case so they need to know the limits and what they can plan for.

moo wrote:
They lost the first stage on landing - it didn't look great when the video feed cut out (lots of nasty black smoke and flames after engine cut off) but it was just confirmed that the first stage was lost. Nothing more yet on how.


Musk has commented:
Looks like thrust was low on 1 of 3 landing engines. High g landings v sensitive to all engines operating at max.

https://twitter.com/elonmusk/status/743097337782763521

Upgrades underway to enable rocket to compensate for a thrust shortfall on one of the three landing engines. Probably get there end of year.

https://twitter.com/elonmusk/status/743099301174247424

Found these in this article:
http://www.theverge.com/2016/6/15/11943 ... e-falcon-9

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Francoflier
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Re: SpaceX - Tests, Launches, Developments

Wed Jun 15, 2016 3:36 pm

Shame...

Rule #1 of space stuff: don't take anything for granted.

It's disappointing, but at this stage, they probably learn a lot more from the failures than from the successes.
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litz
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Re: SpaceX - Tests, Launches, Developments

Wed Jun 15, 2016 5:32 pm

Prize winner of a headline (courtesy FoxNews) :

SpaceX launches satellites, but rocket landing suffers 'unscheduled disassembly'

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