Author Topic: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)  (Read 50879 times)

Offline QuantumG

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #20 on: 11/27/2013 10:19 PM »
If successful, the actual launch isn't going to prove anything significant.

I believe it's the cost of the launch which is the most relevant point. That's what was said at the SES press conference, anyway.
When someone is wishing for a pony, there's little to be gained by suggesting a unicorn would be ever better.. ya know, unless it's sarcasm.

Offline cartman

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #21 on: 11/27/2013 11:30 PM »
So SpaceX has Thursday and Friday available


https://twitter.com/pbdes/status/405592929323843584
Quote
Peter B. de Selding ‏@pbdes

FAA: We've OK'd SpaceX's launch-window requests for Nov. 28 & 29 after refusing requests for 26/27th because of heavy holiday air traffic.

Offline beancounter

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #22 on: 11/28/2013 12:36 AM »
If successful, the actual launch isn't going to prove anything significant.

I believe it's the cost of the launch which is the most relevant point. That's what was said at the SES press conference, anyway.
Well yes, that and reliability.  SES and no one else will stand losing their payloads although they did say this one's fully insured.  Was there some problem with insurance in the past?  New vehicle perhaps?
Beancounter from DownUnder

Offline yg1968

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #23 on: 11/28/2013 02:35 AM »
Did anybody listen to the SpaceX/SES phone call*?  What was the part about being able to increase the engines to 160,000 lbs sea level thrust?  Have we ever heard that before?


* http://www.ses.com/4233325/news/2013/16399975
Quote
US\Canada:  (855) 859-2056
International: (404) 537-3406
Conference ID:   16853657

Thanks for the information! Here is a zipped mp3 recording of the pre-launch teleconference from last Sunday:
http://www.gamefront.com/files/23879140/SpaceX+-SES-8+Pre-Launch+Conference+Nov+24+2013.zip

Offline PreferToLurk

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #24 on: 11/28/2013 03:03 AM »
Did anybody listen to the SpaceX/SES phone call*?  What was the part about being able to increase the engines to 160,000 lbs sea level thrust?  Have we ever heard that before?


* http://www.ses.com/4233325/news/2013/16399975
Quote
US\Canada:  (855) 859-2056
International: (404) 537-3406
Conference ID:   16853657

Thanks for the information! Here is a zipped mp3 recording of the pre-launch teleconference from last Sunday:
http://www.gamefront.com/files/23879140/SpaceX+-SES-8+Pre-Launch+Conference+Nov+24+2013.zip

Thanks for the file!  the exact quote from Elon is: 
Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 pounds of sea level thrust per engine.

I tried to put in all of Elon's little speaking quirks just to eliminate any of my own paraphrasing errors. 
« Last Edit: 11/28/2013 04:57 AM by PreferToLurk »

Offline clarkeo

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #25 on: 11/28/2013 04:28 AM »
Just uploaded the recording to sound cloud might make it a bit easier to listen to

https://soundcloud.com/matthew-clarke-30/spacex-ses-8-pre-launch

Offline Sesquipedalian

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #26 on: 11/28/2013 04:38 AM »
Thanks for the file!  the exact quote from Elon is: 
Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 lbs of sea lvl thrust per engine.

I tried to put in all of Elon's little speaking quirks just to eliminate any of my own paraphrasing errors.

Elon drops the e's from "level"?  How exactly is that pronounced? :P

Offline clarkeo

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #27 on: 11/28/2013 04:50 AM »
This is interesting to hear! Would this increase their payload capacity? Surely this would help with keeping the capable payload high while being able to do RTLS retrieval of the 1st Stage.
I wonder if they are hiding a similar margin on their 2nd Stage engine as well!?

Offline PreferToLurk

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #28 on: 11/28/2013 04:55 AM »
Thanks for the file!  the exact quote from Elon is: 
Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 lbs of sea lvl thrust per engine.

I tried to put in all of Elon's little speaking quirks just to eliminate any of my own paraphrasing errors.

Elon drops the e's from "level"?  How exactly is that pronounced? :P

Ha!  I missed that. ::)  I will edit.   I'm leaving the percent sign though.  ;)
« Last Edit: 11/28/2013 04:58 AM by PreferToLurk »

Online aero

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #29 on: 11/28/2013 04:58 AM »
Well of course. They are the same engines after all. Problem is that the S2 can't proceed with an engine out so driving it to hard risks LOM.
Retired, working interesting problems

Offline GalacticIntruder

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #30 on: 11/28/2013 05:10 AM »
Thanks for the file!  the exact quote from Elon is: 
Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 lbs of sea lvl thrust per engine.

I tried to put in all of Elon's little speaking quirks just to eliminate any of my own paraphrasing errors.

Elon drops the e's from "level"?  How exactly is that pronounced? :P

That is not the first time Elon mentioned something like that. I remember during one his talks/briefings back in the Spring, that he thought his team could push the M1D another 15 percent of performance, over 147kllbf SL.  160-165klbf SL does appear to me as a logical performance target. If or when they meet that, is an open question.
« Last Edit: 11/28/2013 05:11 AM by GalacticIntruder »

Offline solartear

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #31 on: 11/28/2013 05:32 AM »
Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 pounds of sea level thrust per engine.

If I understand correctly, the M1D's 70%-100% official throttling is with 100% being at 85% of its true potential. So with the expanded range as the new 100%, the M1D could actually throttle ~60%-100%.

Being able to throttle down to 60% would put it much closer to the RD-180 throttle range and provide much greater control for landings.

Offline ChrisWilson68

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #32 on: 11/28/2013 05:40 AM »
Great news! Cost reduction found. And one great step on the way to rapid reusability.

Cancel the wet dress rehearsal.

If the WDR wasn't able to detect the three issues that finally ruined the launch attempt last Monday, what's the point of it?

Nobody believes any sort of testing will find 100% of problems.  If it finds 60% of problems, it can still be worth doing.  It all depends on the probability any given bug will be found by the test, the cost of the test, and the cost of the bug not being found.

Online MP99

Quote from: Elon Musk
we're only actually operating the engines at about 85% of their potential, so ah, down the road, future missions, we anticipate being able to crank them up to their full thrust capability of, uh, which would give about 165000 pounds of sea level thrust per engine.

If I understand correctly, the M1D's 70%-100% official throttling is with 100% being at 85% of its true potential. So with the expanded range as the new 100%, the M1D could actually throttle ~60%-100%.

Being able to throttle down to 60% would put it much closer to the RD-180 throttle range and provide much greater control for landings.

Alternatively, they may need to fit a bigger pre-burner or turbopump, which might still have a 70-100% range.

NB 70% of higher thrust will increase burnout g's for lighter payloads.

(Perhaps the solution to this is to carry some prop "ballast", which is used for u/s recovery. But, I'm still having some trouble seeing recovery of u/s used for GTO insertion.)


Also - a question. To optimise for higher thrust, would the engine benefit from a change in expansion ratio?

Cheers, Martin

Online guckyfan

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #34 on: 11/28/2013 08:54 AM »
If they increase thrust by 15% wouldn't they need also ~15% more fuel to take advantage of it? Hard to believe they can stretch the Falcon 9 another 15%. It's very stretched already.

Offline Rabidpanda

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #35 on: 11/28/2013 09:50 AM »
If they increase thrust by 15% wouldn't they need also ~15% more fuel to take advantage of it? Hard to believe they can stretch the Falcon 9 another 15%. It's very stretched already.

Not necessarily, adding more thrust increases performance by reducing gravity losses.
Julian

Offline malu5531

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #36 on: 11/28/2013 10:14 AM »
If they increase thrust by 15% wouldn't they need also ~15% more fuel to take advantage of it? Hard to believe they can stretch the Falcon 9 another 15%. It's very stretched already.

Using same thrust/weight ratio, I calculate the following performance for a stretched F9R+ with 165 klbf M1Ds:

Payload to 26 200x200 km, first stage reused: 15 mT
Payload to 26 200x200 km, expendable: 20 mT

Offline Okie_Steve

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #37 on: 11/28/2013 01:39 PM »
Another possibility is "over-thrust" to compensate for engine out. Consider if they designed the rocket for the expected M1-D thrust and then found out that the engine could produce up to 15% more but the air frame could not handle it without major changes. Hey, life's rough  :) OK, go with the original thrust figures and be happy - unless you lose an engine - and then you can throttle up the remaining 8 by 12.5% or so and keep going with essentially no change of flight profile. Maybe the octoweb needs a bit of tweaking for the increased asymmetric loads but probably not much else. Something to look at after they have the basic design flying well. At some point you have to freeze the design and build/fly it but incremental improvements are part of rockets too. In any event if throttle up is possible it provides a definite boost  ;) to re-usability because the boost back fuel is still available since engine out does not have to automatically increase gravity losses. Assuming of course that you did not lose the *center* engine.

Offline hrissan

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #38 on: 11/28/2013 08:05 PM »
Assuming of course that you did not lose the *center* engine.
It was discussed that may be it is possible to try landing using 2 outer engines...

The main reason to try it is getting remains of center engine for analysis. Dumping the first stage in this situation into ocean is easy, so that's always an option. :)

Offline Jim

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #39 on: 11/28/2013 09:46 PM »
Technically, it never got to T-0 since the vehicle didn't committ

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