Author Topic: SpaceX Falcon 9 : Iridium NEXT Flight 4 : December 22/23, 2017  (Read 24771 times)

Online oiorionsbelt

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however, we should bear in mind that SpaceX has only recovered 18 (by my count) stages at this point.
That this comment was made at all is immensely satisfying. 

Offline woods170

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however, we should bear in mind that SpaceX has only recovered 18 (by my count) stages at this point.
That this comment was made at all is immensely satisfying. 
Indeed. But what is much more important is that three of those recovered booster have already been re-flown with several more re-flights coming up in the next few months.

Offline zubenelgenubi

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An interesting possibility FYI cross-posting from the GCOM-C launch thread:

http://global.jaxa.jp/press/2017/10/20171027_h2af37.html

Launch of Global Changing Observation Mission - Climate "SHIKISAI" (GCOM-C)  and Super Low Altitude Test Satellite TSUBAME" (SLATS) aboard H-IIA Vehicle No. 37

October 27, 2017 (JST)

Mitsubishi Heavy Industries, Ltd.
National Research and Development Agency
Japan Aerospace Exploration Agency (JAXA)

Mitsubishi Heavy Industries, Ltd. (MHI) and the Japan Aerospace Exploration Agency (JAXA) are pleased to announce the launch schedule for Global Changing Observation Mission - Climate "SHIKISAI" (GCOM-C) and Super Low Altitude Test Satellite "TSUBAME" (SLATS) by H-IIA launch vehicle No. 37.

Scheduled date of Launch : December 23 (Sat.), 2017
Launch time                    : 10:26:22 a.m. through 10:48:22 a.m. (JST)
Reserved Launch period   : December 24 (Sun.), 2017 through January 31 (Wed.), 2018
Launch site                     : Yoshinobu Launch Complex at the tanegashima Space Center 

<snip>

And:
Note that as of right now, the start of the launch window for this falls on the exact same minute (!!!) as for the launch of Falcon 9/Iridium NEXT Flight 4 on the opposite side of the Pacific. IF (a very big one) this ultimately happens the two will be <=37 seconds apart, which will be an all time record:o

I very much doubt both will manage to hold on schedule to that point with 57 days left but.....one never knows for sure when will we need split screens.  ;) ;)

Technical info on GCOM-C can be found here, and for SLATS here.
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Offline WizZifnab

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So seems that switching to ASDS landing instead of RTLS on this launch was due to the decision to launch using a previously flown booster.

However, is it possible that it had more to do with taking advantage of the Titanium grid fins for testing an alternate downrange reentry profile, than the fact that it will now be a Block III booster?

Offline IntoTheVoid

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So seems that switching to ASDS landing instead of RTLS on this launch was due to the decision to launch using a previously flown booster.

However, is it possible that it had more to do with taking advantage of the Titanium grid fins for testing an alternate downrange reentry profile, than the fact that it will now be a Block III booster?

During the post-landing processing they remove the grid fins (based on images we've seen in the garage) and the titanium grid fins are mechanically compatible with the mounts for the Al ones, so there's not really any reason to think that this booster will again have the Ti fins, or that if they wanted to test them on a particular re-entry profile that they couldn't have done so already, either on Iridium 3 or one of the east coast launches.

Offline the_other_Doug

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So seems that switching to ASDS landing instead of RTLS on this launch was due to the decision to launch using a previously flown booster.

However, is it possible that it had more to do with taking advantage of the Titanium grid fins for testing an alternate downrange reentry profile, than the fact that it will now be a Block III booster?

During the post-landing processing they remove the grid fins (based on images we've seen in the garage) and the titanium grid fins are mechanically compatible with the mounts for the Al ones, so there's not really any reason to think that this booster will again have the Ti fins, or that if they wanted to test them on a particular re-entry profile that they couldn't have done so already, either on Iridium 3 or one of the east coast launches.

Do the Al and Ti grid fins provide the exact same amounts of control per fin motion?

I could imagine that the Al grids, being closer together and composed of a smaller grid pattern, might provide slightly different pressures to control the rocket than the Ti fins do; their different weights may also impact the control motions.  Neither type of grid fin being "better" or "worse" from a control perspective; just different.

You'd have to program the FCS software running the entry and landing targeting to the type of fin being used, though, no?  Or would you load both sets of response thresholds into the FCS software, and spend a bunch of your processor time selecting between them from menus?

Old-fashioned, "how it's always been done" process would be to tailor the FCS for the specific vehicle's hardware config, I imagine.  I wonder how SpaceX is doing it?
-Doug  (With my shield, not yet upon it)

Offline old_sellsword

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...I could imagine that the Al grids, being closer together and composed of a smaller grid pattern, might provide slightly different pressures to control the rocket than the Ti fins do...

The Titanium fins have the exact same grid pattern and spacing, they just* added an extra row on the end and scalloped the underside.

*Obviously it was more complicated than that

Offline AC in NC

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You'd have to program the FCS software running the entry and landing targeting to the type of fin being used, though, no?  Or would you load both sets of response thresholds into the FCS software, and spend a bunch of your processor time selecting between them from menus?

Old-fashioned, "how it's always been done" process would be to tailor the FCS for the specific vehicle's hardware config, I imagine.  I wonder how SpaceX is doing it?

Putting together a reading of how IIP is handled as well as the unknowns posed by atmospheric conditions and degradation we've seen in AL fins, I'd be surprised if the FCS wasn't written to be able to adapt (as best it can) to whatever control authority is available with the result being no "tailoring" necessary.

Offline FutureSpaceTourist

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Just noticed something that doesn't appear to have been picked up in the Iridium NEXT flight 3 threads.

A few days before the 3rd launch, the FAA issued a minor revision to the launch license (attached):

Quote
Revision 2 - Issued October 6, 2017
   1.   Paragraph (3)(c) changed from "On a flight azimuth of 179.2 degrees" to "On a flight azimuth between 175 and 180 degress

Offline cscott

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Just noticed something that doesn't appear to have been picked up in the Iridium NEXT flight 3 threads.

A few days before the 3rd launch, the FAA issued a minor revision to the launch license (attached):

Quote
Revision 2 - Issued October 6, 2017
   1.   Paragraph (3)(c) changed from "On a flight azimuth of 179.2 degrees" to "On a flight azimuth between 175 and 180 degress
Caused by switch from RTLS to ASDS landing, perhaps?  Gives additional flexibility to target the ASDS even if there are weather issues forcing a slight relocation of the ASDS? Just a wild guess.

Offline FutureSpaceTourist

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Quote
First 2 sats for Launch #4 on their way from AZ factory to VAFB!  Only a little more than 6 weeks away - 12/22! (Tracked via Iridium IoT)

https://twitter.com/iridiumboss/status/928002624670101504

Offline Lar

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"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline FutureSpaceTourist

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Quote
Launch 4 activities on track for a Dec 22nd launch.  Second two of 10 Iridium NEXT sats just left for VAFB - all there by Thanksgiving weekend.  First stage and dispenser onsite.  2018 schedule firming up too... Halfway home!

https://twitter.com/iridiumboss/status/928987644863959041

Online gongora

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This guy makes some sweet models.

Tweet from Oli Braun:
Quote
Very honored to have had the opportunity to make these for @IridiumBoss I hope these 4 will be happy at their new home :)

Online MATTBLAK

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Those models are... amazing :o

Oliver and friend's website:  http://www.buzz-medialabs.de/
« Last Edit: 11/21/2017 10:03 PM by MATTBLAK »
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Offline Zardar

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Those models are... amazing :o

Oliver and friend's website:  http://www.buzz-medialabs.de/

Well, for the 4th model, he should have just made the top bits, and told them to re-use one of the other first-stages.






Online stcks

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There is something sneaky hidden behind the third one ;)

Online cppetrie

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There is something sneaky hidden behind the third one ;)
Well spotted, sir!! Iím seeing the same.

Offline Comga

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There is something sneaky hidden behind the third one ;)
Well spotted, sir!! Iím seeing the same.
Sneaky?
It looks like a fifth Falcon 9.
The clear support is the same as for the three up front.
It may be rotated so only the wiring channel sticks out from behind the third f9.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline mgeagon

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There is something sneaky hidden behind the third one ;)
It appears to be a commercial crew block 5 Falcon 9. It has a Dragon 2 capsule and service module, a black interstage and landing legs, and titanium grid fins. Very nice!
« Last Edit: 11/22/2017 06:10 AM by mgeagon »

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