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#980
by
mn
on 11 Jan, 2018 14:54
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida
.
(Sorry I couldn't find the FH party thead, where is it?)
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#981
by
deruch
on 11 Jan, 2018 14:56
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It gets detanked back to the Lox farm. There is usually enough Lox around for 3-4 attempts on a given day,
one attempt with sub cooled LOX
Well once they start a LOX fill they are committed to one T-0, but if they scrub after LOX loading they have a 90 min recycle, so they are able to do multiple in a day, if they have multiple opportunities. I've been in the rehearsals where they have done this scenario with subcooled LOX.
That can be true for F9 and simultaneously not true for Falcon Heavy because of the ~3x LOX volume needed. In fact, the very requirement for that increased volume of subcooled LOX for FH may be what has allowed SpaceX those additional attempts with F9. Not that they couldn't have expanded their capabilities without FH being a driver, but that it might not have been worthwhile or a priority, etc.
Or are you saying definitively that this is also the case for FH? i.e. that the rehearsals you observed/were in were for FH?
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#982
by
russianhalo117
on 11 Jan, 2018 14:57
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
(Sorry I couldn't find the FH party thead, where is it?)
Probably the space shuttle Static Fires on the pad ahead of STS-1.
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#983
by
abaddon
on 11 Jan, 2018 15:05
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Probably the space shuttle Static Fires on the pad ahead of STS-1.
Not unless they static fired the SRBs, which provided the majority of the thrust at launch.
(Yes, I know you can't static fire SRBs).
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#984
by
Basto
on 11 Jan, 2018 15:07
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
(Sorry I couldn't find the FH party thead, where is it?)
Probably the space shuttle Static Fires on the pad ahead of STS-1.
Please correct me if I am wrong but the STS-1 static fire would have only been for the SSME and would not have included the SRBs.
3 RS-25 engines would have had a combined thrust of 5580 kN. A falcon 9 puts out about 7607 kN.
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#985
by
envy887
on 11 Jan, 2018 15:11
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
(Sorry I couldn't find the FH party thead, where is it?)
Probably the space shuttle Static Fires on the pad ahead of STS-1.
Please correct me if I am wrong but the STS-1 static fire would have only been for the SSME and would not have included the SRBs.
3 RS-25 engines would have had a combined thrust of 5580 kN. A falcon 9 puts out about 7607 kN.
I don't think a 5 million lb class static fire has ever been done in Florida.
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#986
by
DaveS
on 11 Jan, 2018 15:12
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
(Sorry I couldn't find the FH party thead, where is it?)
Probably the space shuttle Static Fires on the pad ahead of STS-1.
There was only one FRF ahead of STS-1, conducted on Feb. 20 1981. You might think of the two FRFs that Challenger underwent, the first one was the planned one and the second one was conducted to diagnose suspected hydrogen leaks in the SSMEs. Then Discovery underwent two FRFs, the standard one prior to the first flight (STS-41D) and a second one prior to STS-26. Atlantis and Endeavour only ever underwent one FRF to qualify their MPS for flight.
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#987
by
AC in NC
on 11 Jan, 2018 15:13
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A reddit user (who has eyes on FH from the SFN webcam) claims that venting was visible from it... WDR??
https://www.reddit.com/r/spacex/comments/7ph9e2/comment/dshowsb
It would make sense. I didn't really understand how they were going to do a WDR, verify the data, and THEN static fire without the fuel warming up to much.
Depends on what "verify" means. If algorithmic checks? could be done in seconds. If humans, a few minutes one would think at the least....
I'm also wondering if the densification factor of the sub-cooled LOX is necessary for a valid FH Static Fire test. I would certainly expect the testing of the load to be important, not so sure about the firing giving that the dense LOX isn't necessary to achieve an orbit.
Is there important test data to be captured from the firing of densified propellant vs. less densified propellant.
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#988
by
jjyach
on 11 Jan, 2018 15:25
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It gets detanked back to the Lox farm. There is usually enough Lox around for 3-4 attempts on a given day,
one attempt with sub cooled LOX
Well once they start a LOX fill they are committed to one T-0, but if they scrub after LOX loading they have a 90 min recycle, so they are able to do multiple in a day, if they have multiple opportunities. I've been in the rehearsals where they have done this scenario with subcooled LOX.
That can be true for F9 and simultaneously not true for Falcon Heavy because of the ~3x LOX volume needed. In fact, the very requirement for that increased volume of subcooled LOX for FH may be what has allowed SpaceX those additional attempts with F9. Not that they couldn't have expanded their capabilities without FH being a driver, but that it might not have been worthwhile or a priority, etc.
Or are you saying definitively that this is also the case for FH? i.e. that the rehearsals you observed/were in were for FH?
My rehearsals were for single stick operations. The limits were based on amount of LOX on hand, but 3 retries = 1 FH amount wise. In our case this was true whether it was at 39A or 40. Not sure if at 39A they are able to use more LOX/have it ready.
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#989
by
deruch
on 11 Jan, 2018 15:25
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I'm also wondering if the densification factor of the sub-cooled LOX is necessary for a valid FH Static Fire test. I would certainly expect the testing of the load to be important, not so sure about the firing giving that the dense LOX isn't necessary to achieve an orbit.
Is there important test data to be captured from the firing of densified propellant vs. less densified propellant.
History shows that there can be appreciable and significant differences. Just ask Spacecom (AMOS-6).
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#990
by
drnscr
on 11 Jan, 2018 15:26
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A reddit user (who has eyes on FH from the SFN webcam) claims that venting was visible from it... WDR??
https://www.reddit.com/r/spacex/comments/7ph9e2/comment/dshowsb
It would make sense. I didn't really understand how they were going to do a WDR, verify the data, and THEN static fire without the fuel warming up to much.
Depends on what "verify" means. If algorithmic checks? could be done in seconds. If humans, a few minutes one would think at the least....
I'm also wondering if the densification factor of the sub-cooled LOX is necessary for a valid FH Static Fire test. I would certainly expect the testing of the load to be important, not so sure about the firing giving that the dense LOX isn't necessary to achieve an orbit.
Is there important test data to be captured from the firing of densified propellant vs. less densified propellant.
Fly as you test, test as you fly
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#991
by
Hauerg
on 11 Jan, 2018 15:29
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Different fuel-mass, so yes.
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#992
by
Nomadd
on 11 Jan, 2018 15:39
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When was the last time this much energy has been (deliberately) unleashed at the Cape?
I have tremendous new respect for the reaction frame, and its attachment points to terra firma, for holding onto this beast, even for a small collection of seconds. How much weight is shed during a 12 second burn, with a best guess at staggered engine start?
This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
(Sorry I couldn't find the FH party thead, where is it?)
Better check the direction the exhaust winds up going. You're sinking Florida even more. (The Daffy Duck method of propelling a sailboat by aiming a fan into the sail actually could have worked)
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#993
by
john smith 19
on 11 Jan, 2018 15:46
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I don't think a 5 million lb class static fire has ever been done in Florida.
Obvious question would be if the Saturn V was static fired before liftoff.
That's would be the yardstick for this activity, with the N-1 for the number of simultaneous engines running (as in separate turbo-pump/nozzle packages).
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#994
by
AC in NC
on 11 Jan, 2018 15:51
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Different fuel-mass, so yes.
Thanks. On retrospect, and somewhat obviously, the vibrations that have complicated FH would be different and important to capture at the boundary case.
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#995
by
IanThePineapple
on 11 Jan, 2018 15:51
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I'm pretty sure a Saturn V was never static fired at the Cape. I know the shuttle did, along with the post-ignition aborts
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#996
by
the_other_Doug
on 11 Jan, 2018 15:54
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This is probably one way of dealing with sea level rise, just line up a few FH's and raise florida .
Name, other way around. When KSC was preparing to launch the first Saturn V, the running joke was that bets were being taken -- would the rocket rise, or would Florida sink? 😊
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#997
by
RoboGoofers
on 11 Jan, 2018 15:59
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Is there important test data to be captured from the firing of densified propellant vs. less densified propellant.
it's also not just a test of the firing. There might be different issues that arise when loading and unloading subcooled props that don't cause any problem at 'normal' temps.
remember the helium COPVs?
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#998
by
clongton
on 11 Jan, 2018 16:56
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I'm also wondering if the densification factor of the sub-cooled LOX is necessary for a valid FH Static Fire test.
Standard procedure is to proceed exactly the same as a launch.
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#999
by
AC in NC
on 11 Jan, 2018 17:05
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Is there important test data to be captured from the firing of densified propellant vs. less densified propellant.
it's also not just a test of the firing. There might be different issues that arise when loading and unloading subcooled props that don't cause any problem at 'normal' temps.
remember the helium COPVs?
I acknowledged that specifically and it was not part of my question.
.