SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[Comga]

It is beginning to be a long week. I am hitting F5 every minute to check if there is news about RTF, if NET date holds. Until now we have:

Rocket at launch site
Orbcom payload at launch site
NET: Dec 15/16
Land Landing (awaiting for FAA aproval)
Sitill dont have a date for hot fire test?

Anything I am missing?

L2 membership 
If you had that you wouldn't have to ask what's missing.
You would know it if it is known.
But that's pretty much it as of right now.

[kch]

What are the launch windows if they try to go next week (15/16)?

Well, which one -- next week or the 15th/16th? 

[Rocket Rancher]

If T-0 is during off-hours, there would be a better chance of a landing attempt being granted at CCAFS. The test would have minimal impact of daily operations ... IMHO

[scourgio]

Does SpaceX plan to run a wet dress rehearsal for the flight?  I know they haven't performed WDR's for a while, but given the changes to the fueling procedure, I was just wondering.

[rpapo]

Does SpaceX plan to run a wet dress rehearsal for the flight?  I know they haven't performed WDR's for a while, but given the changes to the fueling procedure, I was just wondering.

IIRC, the Wet Dress Rehearsal is the same as the Static Fire.  They go through everything, up to and including lighting the candle briefly.

[Comga]

If T-0 is during off-hours, there would be a better chance of a landing attempt being granted at CCAFS. The test would have minimal impact of daily operations.

Please include a disclaimer, like IMHO, unless you are basing this on a discussion with principals involved in the approval seeking or granting.  We out here have few facts about the approval process and the criteria.

Others might has said "Fixed that for you" and changed it to "... would there be a better chance..." to make it a question, but I will just suggest that for next time.

[LaunchedIn68]

Has any work actually been done yet on SLC-13 to prepare it for RTLS?  The latest images on Google show it over grown and still containing Atlas pad ruins?  I haven't seen any recent discussions on it either.

[georgegassaway]

Lots of work at LC-13.  Though I wonder if they went to a leisurely pace during the RTF stand down and now have to hurry up with the apparent (?) recent decision to try to do the RTF landing there rather than ASDS.  Here's a couple of satellite (not Google) pics from a few months ago (August, possibly September).

Reportedly, the landing pad has the SpaceX logo on it, but no pics that I know of.

- George Gassaway

[Paul_G]

Has any work actually been done yet on SLC-13 to prepare it for RTLS?  The latest images on Google show it over grown and still containing Atlas pad ruins?  I haven't seen any recent discussions on it either.

Check out the thread at http://forum.nasaspaceflight.com/index.php?topic=36513.180

Paul

[edkyle99]

Here's a time-lapse of the construction at X1.
http://gfycat.com/PhysicalSourCrane

Interesting that they've centered the landing pad near the spot where the original Atlas ICBM gantry was parked during launches.

 - Ed Kyle

[dorkmo]

What are the launch windows if they try to go next week (15/16)?

apparently its 15 and 16

Per L2 the launch window is pretty long.

December 15: 2154-0054 local.

Static Fire early next week.

[dorkmo]

Here's a time-lapse of the construction at X1.
http://gfycat.com/PhysicalSourCrane

Interesting that they've centered the landing pad near the spot where the original Atlas ICBM gantry was parked during launches.

 - Ed Kyle

appears to to be centered nearish 28.485714, -80.542923 aka 28°29'08.6"N 80°32'34.5"W

i was hoping for a fun number. missed an opportunity to use close by -80.543210  :/

[MarekCyzio]

Do we know what direction will F9 fly? I guess this will be the same direction booster will come from unless SpaceX makes some direction changes mid-flight (highly unlikely). I wonder if this overpressure map is still valid + what areas of CCAFS will have to be evacuated/off limits.

[EchozAurora]

*fingers crossed* the NET date holds!  I went ahead and took the 16th off just in case either way, really hoping I can go watch this one in person.

[edkyle99]

LC 13 at work, Atlas 15D on November 24, 1959, from the awesome San Diego Air and Space Museum Flickr project.  The X1 landing pad is located generally where the service tower is parked in this image.

 - Ed Kyle

[Coastal Ron]

Do we know what direction will F9 fly? I guess this will be the same direction booster will come from unless SpaceX makes some direction changes mid-flight (highly unlikely). I wonder if this overpressure map is still valid + what areas of CCAFS will have to be evacuated/off limits.

If you want to know where the ASDS is, check out the SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2 forum.

[Kabloona]

On that subject, a cross-post from the ASDS thread:

... here is a link to the map created by darga for OG2 and posted earlier. The barge location is around 80 miles offshore of JAX, much closer than previous missions...

The coordinates are from the FAA transmitter permit application.

I started a map with the assumption that they are two separate landing areas for two missions. https://www.google.com/maps/d/edit?mid=zXmjsQgIEPtk.kEXviMLLYGIk

[Remes]

SpaceX struts are made of steel. 

Any specific reason why they chose steel over aluminum?

[DanseMacabre]

SpaceX struts are made of steel. 

Any specific reason why they chose steel over aluminum?

Steel *is* stronger; just the strength costs weight.

[OneSpeed]

SpaceX struts are made of steel. 

Any specific reason why they chose steel over aluminum?

Steel *is* stronger; just the strength costs weight.

It also depends what mode you are using to load the material.

A solid rod in pure tension can be stronger in steel, especially iconel, for the same weight.

However, a beam that is designed to resist bending, especially if in multiple directions like a tube, can be stronger for the same weight in aluminium. This is because aluminium has a lower density, and so for the same wall thickness, an aluminium tube can be a much larger diameter. Stiffness and ultimate strength go up proportionally to the 4th power of the diameter:

MI for Solid Round Beams = (pi * (OD^4 - ID^4)) / 64
Deflection = (length3 * force) / (3 * E * MI)
Bending Stress = (force * length) / (MI / (0.5 * height))

So both stiffness and ultimate bending strength can be much greater in aluminium.

A guitar string works well in steel.
A rocket fuselage works well in aluminium.

So, for the strut, they chose steel.

Edited to add exponent symbols