Author Topic: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion  (Read 428565 times)

Online Roy_H

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1040 on: 01/13/2018 04:03 AM »
Per the update thread the SF is potentially slipping to Monday....

Monday is a holiday, what's the rush? Give the guys a break.
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Offline ChrisGebhardt

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1041 on: 01/13/2018 04:16 AM »
Per the update thread the SF is potentially slipping to Monday....

Monday is a holiday, what's the rush? Give the guys a break.

Absolutely no evidence that they are rushing.  The fact that they are pushing this two days, in fact, directly contradicts an assertion that they are rushing in any way with this.

Federal holidays do not prevent critical operations from occurring at the space center.  Moreover, federal holidays, are not a guaranteed day off in the US.
« Last Edit: 01/13/2018 04:18 AM by ChrisGebhardt »

Offline john smith 19

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1042 on: 01/13/2018 08:15 AM »
Think of the tail service mast at base of the core.  It is on the opposite side of the TEL.  Now take another core and make it the left booster.  The attach points of the booster to the core are on the right side of the booster.   Now, duplicate the left booster and to attach it to the core, it has to rotated 180 degrees.  This now puts TSM on the TEL side of the vehicle.

Titan had right and left boosters.  Delta IV Heavy had three unique cores, that is why it was expensive
It's these sorts of quite subtle design points that make the whole "Let's make a big rocket by clustering a bunch of common stage together" idea quite a bit trickier IRL than it seems on paper.

In hindsight it's pretty impressive that SX have gotten away with only needing 2 separate designs and being able to reuse single stick F9 boosters as the boosters, rather than a whole new booster design.
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Offline Jim

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1043 on: 01/13/2018 12:40 PM »
Think of the tail service mast at base of the core.  It is on the opposite side of the TEL.  Now take another core and make it the left booster.  The attach points of the booster to the core are on the right side of the booster.   Now, duplicate the left booster and to attach it to the core, it has to rotated 180 degrees.  This now puts TSM on the TEL side of the vehicle.

Titan had right and left boosters.  Delta IV Heavy had three unique cores, that is why it was expensive
It's these sorts of quite subtle design points that make the whole "Let's make a big rocket by clustering a bunch of common stage together" idea quite a bit trickier IRL than it seems on paper.

In hindsight it's pretty impressive that SX have gotten away with only needing 2 separate designs and being able to reuse single stick F9 boosters as the boosters, rather than a whole new booster design.

Atlas V Heavy would have only required one design for all three boosters since all cores can handle solid boosters.

Things would have been much different if Altas V had won the lionís share and heavies of the EELV order.
« Last Edit: 01/13/2018 12:43 PM by Jim »

Offline Karloss12

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1044 on: 01/13/2018 02:05 PM »
Think of the tail service mast at base of the core.  It is on the opposite side of the TEL.  Now take another core and make it the left booster.  The attach points of the booster to the core are on the right side of the booster.   Now, duplicate the left booster and to attach it to the core, it has to rotated 180 degrees.  This now puts TSM on the TEL side of the vehicle.

Titan had right and left boosters.  Delta IV Heavy had three unique cores, that is why it was expensive
It's these sorts of quite subtle design points that make the whole "Let's make a big rocket by clustering a bunch of common stage together" idea quite a bit trickier IRL than it seems on paper.

In hindsight it's pretty impressive that SX have gotten away with only needing 2 separate designs and being able to reuse single stick F9 boosters as the boosters, rather than a whole new booster design.
The FH side cores used for the demo lift the centre core from the octoweb base only.  They are actually designed in a regular F9 launch to lift a second stage and payload positioned on top of them.  This suggests that the tankage and structure above the octoweb is excessively over designed (when used as FH side cores).  Perhaps there is a bending moment along the side cores length when used for FH.
With BFR in the pipework to ultimately replace FH, I doubt there will be a specially designed light weight side core.
« Last Edit: 01/13/2018 02:09 PM by Karloss12 »

Offline nicp

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1045 on: 01/13/2018 03:21 PM »
Look like titanium grid fins on the boosters, Al on the core.
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Online Cherokee43v6

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1046 on: 01/13/2018 03:29 PM »
Per the update thread the SF is potentially slipping to Monday....

Monday is a holiday, what's the rush? Give the guys a break.

Absolutely no evidence that they are rushing.  The fact that they are pushing this two days, in fact, directly contradicts an assertion that they are rushing in any way with this.

Federal holidays do not prevent critical operations from occurring at the space center.  Moreover, federal holidays, are not a guaranteed day off in the US.

I would point out that from a safety perspective, doing a high-risk operation, like the FH's first static fire, on a Holiday during which most other operations at the facility would be shut down actually makes a ton of sense.  If something goes wrong and there is an RUD there is not a mad scramble (as was the case with AMOS 6) to safely shut down and evacuate surrounding operations.
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Offline shuttlefan

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1047 on: 01/13/2018 03:43 PM »
Will the FH remain upright all through the weekend and through the potential static fire Monday, and is it possible they will do another WDR today or tomorrow?

Offline Pete

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1048 on: 01/13/2018 03:50 PM »
Think of the tail service mast at base of the core.  It is on the opposite side of the TEL.  Now take another core and make it the left booster.  The attach points of the booster to the core are on the right side of the booster.   Now, duplicate the left booster and to attach it to the core, it has to rotated 180 degrees.  This now puts TSM on the TEL side of the vehicle.

Titan had right and left boosters.  Delta IV Heavy had three unique cores, that is why it was expensive
It's these sorts of quite subtle design points that make the whole "Let's make a big rocket by clustering a bunch of common stage together" idea quite a bit trickier IRL than it seems on paper.

In hindsight it's pretty impressive that SX have gotten away with only needing 2 separate designs and being able to reuse single stick F9 boosters as the boosters, rather than a whole new booster design.

Atlas V Heavy would have only required one design for all three boosters since all cores can handle solid boosters.

Things would have been much different if Altas V had won the lionís share and heavies of the EELV order.
Wouldn't the Altas V's asymmetric profile have made bolting 3 side-by-side more difficult?

Offline Jim

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1049 on: 01/13/2018 04:44 PM »
Think of the tail service mast at base of the core.  It is on the opposite side of the TEL.  Now take another core and make it the left booster.  The attach points of the booster to the core are on the right side of the booster.   Now, duplicate the left booster and to attach it to the core, it has to rotated 180 degrees.  This now puts TSM on the TEL side of the vehicle.

Titan had right and left boosters.  Delta IV Heavy had three unique cores, that is why it was expensive
It's these sorts of quite subtle design points that make the whole "Let's make a big rocket by clustering a bunch of common stage together" idea quite a bit trickier IRL than it seems on paper.

In hindsight it's pretty impressive that SX have gotten away with only needing 2 separate designs and being able to reuse single stick F9 boosters as the boosters, rather than a whole new booster design.

Atlas V Heavy would have only required one design for all three boosters since all cores can handle solid boosters.

Things would have been much different if Altas V had won the lionís share and heavies of the EELV order.
Wouldn't the Altas V's asymmetric profile have made bolting 3 side-by-side more difficult?

No, Atlas V was designed from the beginning to do the 3 core heavy.  They just never finished the foreward attachment points and the pad GSE.

The two strapons would occupy where the solids would go.
« Last Edit: 01/13/2018 04:45 PM by Jim »

Offline hoku

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1050 on: 01/13/2018 07:00 PM »
Look like titanium grid fins on the boosters, Al on the core.
Yes, larger titanium fins are required for increased control authority on the boosters during atmospheric descent. This is due to the more aerodynamic shape of the booster's top, which becomes the "tail" during descent.

Core keeps its blunt top, thus smaller Al fins suffice for controlling atmospheric descent.

Offline meekGee

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1051 on: 01/13/2018 07:46 PM »
Look like titanium grid fins on the boosters, Al on the core.
Yes, larger titanium fins are required for increased control authority on the boosters during atmospheric descent. This is due to the more aerodynamic shape of the booster's top, which becomes the "tail" during descent.

Core keeps its blunt top, thus smaller Al fins suffice for controlling atmospheric descent.
I know this is what they said, but it sounds so odd...  The other alternative would have been spoilers that are aerodynamic on the way up, but separate the flow when flying backwards...

Not that I don't like the Titanium fins...
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Offline Semmel

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1052 on: 01/13/2018 08:13 PM »
Look like titanium grid fins on the boosters, Al on the core.
Yes, larger titanium fins are required for increased control authority on the boosters during atmospheric descent. This is due to the more aerodynamic shape of the booster's top, which becomes the "tail" during descent.

Core keeps its blunt top, thus smaller Al fins suffice for controlling atmospheric descent.
I know this is what they said, but it sounds so odd...  The other alternative would have been spoilers that are aerodynamic on the way up, but separate the flow when flying backwards...

Not that I don't like the Titanium fins...

My take on it is:
Titanium fins are required for the side boosters to work. For the reentry heating, they would need the centre core to also have titanium grids for the high velocity. But I guess the rocket has enough spare performance to perform a breaking burn instead of a boostback to reduce velocity to normal reentry conditions. The alternative is, they accept the fact that the centre core gets cooked fins and they dont care because they dont plan to reuse this particular core anyway. So great if the reentry works, no big loss if it doesnt.

Offline nicp

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1053 on: 01/13/2018 08:13 PM »
Does it not also suggest the core wonít be really fast? Or high? OCISLY is out I think?
EDIT: By out I mean deployed, in use in some manner, out of port.
« Last Edit: 01/13/2018 08:17 PM by nicp »
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Offline meekGee

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1054 on: 01/13/2018 08:15 PM »
Look like titanium grid fins on the boosters, Al on the core.
Yes, larger titanium fins are required for increased control authority on the boosters during atmospheric descent. This is due to the more aerodynamic shape of the booster's top, which becomes the "tail" during descent.

Core keeps its blunt top, thus smaller Al fins suffice for controlling atmospheric descent.
I know this is what they said, but it sounds so odd...  The other alternative would have been spoilers that are aerodynamic on the way up, but separate the flow when flying backwards...

Not that I don't like the Titanium fins...

My take on it is:
Titanium fins are required for the side boosters to work. For the reentry heating, they would need the centre core to also have titanium grids for the high velocity. But I guess the rocket has enough spare performance to perform a breaking burn instead of a boostback to reduce velocity to normal reentry conditions. The alternative is, they accept the fact that the centre core gets cooked fins and they dont care because they dont plan to reuse this particular core anyway. So great if the reentry works, no big loss if it doesnt.
I'm figuring Titanium fins were first developed for fast reentries, but once developed, it became simpler to use them on the slow-moving central cores - since they already existed.
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Online TaurusLittrow

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1055 on: 01/13/2018 08:24 PM »
Any information or informed speculation on the launch window (UTC) for Falcon Heavy?

Offline Lars-J

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1056 on: 01/13/2018 08:32 PM »
Any information or informed speculation on the launch window (UTC) for Falcon Heavy?

I think someone else drew a chart for this earlier (forgot who), but basically - If the idea is to launch the roadster on a direct transfer orbit, then 6pm (local) is the optimal time. But they probably want to launch during daylight, so my bet would be mid-to-late afternoon. (Which would still work, since the upper stage could coast until TMI)

So 3-5pm local time would be my educated guess. (20:00-2300 UTC)
« Last Edit: 01/13/2018 08:32 PM by Lars-J »

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1057 on: 01/13/2018 08:43 PM »
Does it not also suggest the core wonít be really fast? Or high? OCISLY is out I think?
EDIT: By out I mean deployed, in use in some manner, out of port.
No.  It just suggests that they have have aluminum grid fins and they're good enough for the core for this one mission.  I can't find the reference now but my understanding is that this FH will only fly once.  Next FH will be all Block 5 cores and therefore all titanium fins.
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Offline nicp

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1058 on: 01/13/2018 09:03 PM »
But then why do the boosters have titanium grid fins? I believe these are all 'old' designs.
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Offline ziceva

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Re: SpaceX FH : Falcon Heavy Demo : early 2018 : Discussion
« Reply #1059 on: 01/13/2018 09:07 PM »
But then why do the boosters have titanium grid fins? I believe these are all 'old' designs.

It has been discussed here multiple times ... they need the big titanium grid fins because the different aerodinamics of the booster cores with their streamlined nosecaps ... (the air "adheres" to these and it seems that this decreases the control authority of the grid fins)

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