SpaceX Falcon Heavy : Arabsat 6A : LC-39A : April 11, 2019 - DISCUSSION

[deruch]

Mr. Steven has departed port also, the entire fleet is on deck for this FH mission!
   
— SpaceXFleet Updates (@SpaceXFleet) April 6, 2019
https://twitter.com/SpaceXFleet/status/1114557883813957632

So what can Mr Steven do without arms and a net?
Something with the big, round, raft?

Practice tracking and maneuvering/positioning runs on a live fairing.  I know they haven't managed to catch a fairing yet, but that hasn't been because they had trouble with the arms.  It's been because they haven't managed to get into the exact right position in time.  So, they can practice all the stuff except for the actual catching.  Plus recover the halves from the water, as flyright pointed out.

[cgrunska]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

[spacenut]

They may not have a booster to expend.  They do want reuse. 

[tleski]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

It was extensively discussed earlier in this thread. As far as I remember the most likely reason is that F9 and FH performance was much lower at the time of signing the contract.

[cgrunska]

sorry, i got to page 5 or 6 and wasn't finding any references to it, so i skipped ahead. That makes sense, the boosters are wildly more powerful now. Surely they could move rockets around and sign a new contract, though for spacex they also probably want or need more demonstrations to give other partners/potential partners more data to want to use the rocket.

the discussion is on page 9 and 10, by the way (in case anyone else comes along with this question)

[envy887]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

We don't know what SpaceX charges for an expended F9 booster, but it's probably more than they charge for FH with 3 recovered boosters.

[Orbiter]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

F9 can carry this payload to GTO and be recovered.

[envy887]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

F9 can carry this payload to GTO and be recovered.

Only to a sub-sync GTO. Arabsat probably contracted for considerably more performance.

[Pete]

On why F9H  :

Customer paid for FH, cusomer gets FH.
Also, SpaceX is *very* glad to have a good reason/excuse to fly FH at all. Especially with a paying cargo. Double especially with nice big ample generous margins. SpaceX wants a higher number of launches on that FH wiki page!



About the performance of FH:
Musk states "Max thrust of 2550 tons will be almost 10% higher than Falcon Heavy demo mission last year"
110% of the demo's thrust would be 2559 metric tons, so 2550 metric tons sounds just right for "almost 10 % higher"
If it was in short tons, silly tons or imperial tons, then the numbers don't match.

Besides, this is SpaceX.
You know, the (only?) US rocket launcher than measures in Kilometers, Tons, Meters per Second and sometimes even in KiloNewtons.

[Pete]

You’re wrong, Pete.

Care to explain?

And let's begin with your delusion that if Y = 90% of  X, then X is 10% more than Y.
That sort of math would have gotten me failing math at school, much less in an engineering world.

[lonestriker]

You’re wrong, Pete.

Care to explain?

And let's begin with your delusion that if Y = 90% of  X, then X is 10% more than Y.
That sort of math would have gotten me failing math at school, much less in an engineering world.

Just plug in real numbers to test your assertion:

X = 100
Y = 0.90 * X = 90

"Y is 90% of X", so 90 out of 100 checks out.

"X is 10% more than Y"  is your assertion, but Y * 1.10 = 99, not 100

Percentages going each direction are different.

[Alexphysics]

This launch was contracted to be launched on a FH so it launches on a FH, they could have changed to an expendable F9 but they didn't have any reason for that. Other customers did have a big reason and it was that FH was being heavily delayed but this satallite had the launch contracted for a 2018 launch so the delay is not too big and it would have been silly to revert to F9. And the thrust is not 2550 metric tons but rather 2550 US tons which are different, the thrust of the demo FH was lower because it was a weird combination of the older blocks of F9 FT, this one is the one that matches the performance on their website that are supposed to be the numbers for Block 5.

[sghill]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

...because they need to certify the FH vehicle with DOD, and that means launches- price be damned.

This is called a "lost leader".

[smootherpebble]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

...because they need to certify the FH vehicle with DOD, and that means launches- price be damned.

This is called a "lost leader".

I don't think Lockheed Martin or KACST would be happy to hear their launch called a "loss leader". That's certainly not what this is.

Edit: Typo

[daveklingler]

Do we know why spacex is launching on the FH when a falcon 9 can carry this to GEO with an expended booster? They have like 20,000kg of margins on this flight which seems...excessive.

...because they need to certify the FH vehicle with DOD, and that means launches- price be damned.

This is called a "lost leader".

I don't think Lockheed Martin or KACST would be happy to hear their launch called a "lost leader". That's certainly not what this is.

Do you mean "loss leader", or is there some turn of phrase here I'm missing?

At any rate, I don't think in any way it would be termed a loss leader. It's unlikely SpaceX is losing money on this launch. As several people have observed, the customer paid for a FH launch, and that's what they're getting.

[matthewkantar]

A lost leader is no leader at all, must be a typo for "loss leader."

Over on the update thread there is an absolutely fantastic picture of the business end of Falcon Heavy. This my first time seeing such a clear high-res shot. It raises some questions that I have not been able to answer, any help would be great.

There are some sort of lugs that I can't figure out, in red. The yellow are some of the eight (larger but similar looking) hold down/ release lugs.

The blue is the main hinge for separating the cores in flight, how do the green gizmos work? Does the one on the center core fold up leaving the bit on the side booster to hang in the wind?

It looks like all of the cloth components on the bottom of the rocket have been replaced with bilevel shields marked in orange. How do these allow gimbaling? Does the gray part slide on the black part? Bonus question: are the bumpers between the bells "remove before flight" items?

What material is the greenish stuff that comprises the bulk of the dance floor?

[lrk]

What material is the greenish stuff that comprises the bulk of the dance floor?

See this L2 post: https://forum.nasaspaceflight.com/index.php?topic=43290.msg1723251#msg1723251

[Coastal Ron]

The yellow are some of the eight (larger but similar looking) hold down/ release lugs.

Those are the attachment points for the legs, and as far as I know they are only hinge points.

[stcks]

There are some sort of lugs that I can't figure out, in red.

How do these allow gimbaling? Does the gray part slide on the black part? Bonus question: are the bumpers between the bells "remove before flight" items?

99% sure the red circled items are the lift attachment points and also double as the points for the transport ring attachments.

We first saw the gimbal sleeve (I made this term up just now) on SES-10 iirc and yes, that's how they work.

[FlattestEarth]

99% sure the red circled items are the lift attachment points and also double as the points for the transport ring attachments.

True