3) Crossfeed is MUCH better. it empties and ditches the side boosters sooner while having the most thrust available and a full core stage at staging. The only way to improve on crossfeed would be to stretch the upper stage.
Quote from: rsdavis9 on 05/30/2018 11:56 amSomething like the current profile but shutdown the center core part way up and then restart center after staging. Alternatively deep throttling could do much of this without stopping and restarting.EDIT: we do know that the throttling of the first FH was VERY conservative. They only ran the engines at 90% thrust? How deep can a M1D throttle? 30% ?Probably a LOT of room for improvement.(1) Without some changes to the Octoweb, only three of the engines can be started (or restarted) during flight.(2) It is not clear (to me, at least) whether the Merlins can be throttled down from 100% to 60% (40% down), or from 100% to 40% (60% down).
Something like the current profile but shutdown the center core part way up and then restart center after staging. Alternatively deep throttling could do much of this without stopping and restarting.EDIT: we do know that the throttling of the first FH was VERY conservative. They only ran the engines at 90% thrust? How deep can a M1D throttle? 30% ?Probably a LOT of room for improvement.
Apparently Europa Clipper direct to Jupiter is marginal currently on FH. I wonder if crossfeed would improve those margins enough to make it worth the investment?Of course that assumes that there is any way that SpaceX could get the contract to launch Europa Clipper, which seems impossible for political reasons.
We could really dial it up to as much performance as anyone could ever want. If we wanted to we could actually add two more side boosters and make it Falcon Super Heavy
>Or you can go full Kerbal. QuoteWe could really dial it up to as much performance as anyone could ever want. If we wanted to we could actually add two more side boosters and make it Falcon Super Heavy
I love crossfeed, I wish they were developing it, it'd be the coolest feature of any flying rocket.But it's not needed, sadly.
Apparently Europa Clipper direct to Jupiter is marginal currently on FH. I wonder if crossfeed would improve those margins enough to make it worth the investment?Of course that assumes that there is any way that SpaceX could get the contract to launch Europa Clipper, which seems is impossible for political reasons.
Quote from: cscott on 05/30/2018 03:13 pmApparently Europa Clipper direct to Jupiter is marginal currently on FH. I wonder if crossfeed would improve those margins enough to make it worth the investment?Of course that assumes that there is any way that SpaceX could get the contract to launch Europa Clipper, which seems impossible for political reasons.It also assumes that developing crossfeed is not more expensive than stretching the second stage.Elon: We’ve already stretched the upper stage once. Easiest part of the rocket to change.The capacity of FH is reportedly marginal and unclear on the direct jupiter injection for EC.Hardware mods are one way of fixing it - changing the spec and going from 'won't quite make it' to 'will just make it' are quite plausible.As is a five ton kick stage.Or you can go full Kerbal. QuoteWe could really dial it up to as much performance as anyone could ever want. If we wanted to we could actually add two more side boosters and make it Falcon Super Heavy
Quote from: EnigmaSCADA on 05/29/2018 11:41 pmI'm curious about staging strategies but simply don't know enough to fully figure various options out. Irrespective of the economics, business strategy, or likelihood of implementation, what sort of impact on payload and reachable orbits would the following setups result in?1) shortening the center core and elongating the 2nd stage by the same amount for more prop in the US.2) launch using side cores, igniting center core at booster sep. Is this even possible? I presume this would make the core expendable also?3) crossfeed vs the current throttling of the core. Does this result in the same performance as scenario 2?Lastly, can anyone point me to a good resource that compares various parallel vs serial staging strategies? I would have thought this would be easy information to come across but maybe I'm just struggling with right search terms.1) doesn't help much unless also combined with crossfeed2) gravity losses probably cause this to be worse than the current launch profile with the center core throttling down early.3) Crossfeed is MUCH better. it empties and ditches the side boosters sooner while having the most thrust available and a full core stage at staging. The only way to improve on crossfeed would be to stretch the upper stage.
I'm curious about staging strategies but simply don't know enough to fully figure various options out. Irrespective of the economics, business strategy, or likelihood of implementation, what sort of impact on payload and reachable orbits would the following setups result in?1) shortening the center core and elongating the 2nd stage by the same amount for more prop in the US.2) launch using side cores, igniting center core at booster sep. Is this even possible? I presume this would make the core expendable also?3) crossfeed vs the current throttling of the core. Does this result in the same performance as scenario 2?Lastly, can anyone point me to a good resource that compares various parallel vs serial staging strategies? I would have thought this would be easy information to come across but maybe I'm just struggling with right search terms.
Quote from: envy887 on 05/30/2018 01:05 pmQuote from: EnigmaSCADA on 05/29/2018 11:41 pmI'm curious about staging strategies but simply don't know enough to fully figure various options out. Irrespective of the economics, business strategy, or likelihood of implementation, what sort of impact on payload and reachable orbits would the following setups result in?1) shortening the center core and elongating the 2nd stage by the same amount for more prop in the US.2) launch using side cores, igniting center core at booster sep. Is this even possible? I presume this would make the core expendable also?3) crossfeed vs the current throttling of the core. Does this result in the same performance as scenario 2?Lastly, can anyone point me to a good resource that compares various parallel vs serial staging strategies? I would have thought this would be easy information to come across but maybe I'm just struggling with right search terms.1) doesn't help much unless also combined with crossfeed2) gravity losses probably cause this to be worse than the current launch profile with the center core throttling down early.3) Crossfeed is MUCH better. it empties and ditches the side boosters sooner while having the most thrust available and a full core stage at staging. The only way to improve on crossfeed would be to stretch the upper stage.After KSP taught me rocket science, crossfeed & asparagus staging seemed like a make-or-break thing - why would you ever operate a three-core rocket without it? But it turns out, in reality the weight of the engines and tankage is proportionately much lower IRL than in KSP, and this provides a corresponding dramatic decrease in the benefits you get out of crossfeed and out of additional stages.
Why did you even bother to bring the Off-Topic subject of Europa Clipper into this discussion? See your own last line (bolded).
AIR FORCESpace Exploration Technologies Corp. (SpaceX), Hawthorne, California, has been awarded a $130,000,000 firm-fixed-price contract, for launch services to deliver the Air Force Space Command-52 satellite to its intended orbit. This launch service contract will include launch vehicle production and mission, as well as integration, launch operations and spaceflight worthiness activities. Work will be performed in Hawthorne, California; Kennedy Space Center, Florida; and McGregor, Texas, and is expected to be completed by September 2020. This award is the result of a competitive acquisition, and two proposals were received. Fiscal 2018 space procurement funds in the amount of $130,000,000 will be obligated at the time of award. The Contracting Division, Launch Systems Enterprise Directorate, Space and Missile Systems Center, Los Angeles Air Force Base, California, is the contracting activity (FA8811-18-C-0003). (Awarded June 20, 2018)
Quote from: docmordrid on 06/22/2018 02:10 amhttps://twitter.com/jeff_foust/status/1009912347362844672?s=19@jeff_foustSpaceX has won a $130M contract from the US Air Force to launch the AFSPC-52 mission on a Falcon Heavy: https://t.co/UC6wV436GWQuoteAIR FORCESpace Exploration Technologies Corp. (SpaceX), Hawthorne, California, has been awarded a $130,000,000 firm-fixed-price contract, for launch services to deliver the Air Force Space Command-52 satellite to its intended orbit. This launch service contract will include launch vehicle production and mission, as well as integration, launch operations and spaceflight worthiness activities. Work will be performed in Hawthorne, California; Kennedy Space Center, Florida; and McGregor, Texas, and is expected to be completed by September 2020. This award is the result of a competitive acquisition, and two proposals were received. Fiscal 2018 space procurement funds in the amount of $130,000,000 will be obligated at the time of award. The Contracting Division, Launch Systems Enterprise Directorate, Space and Missile Systems Center, Los Angeles Air Force Base, California, is the contracting activity (FA8811-18-C-0003). (Awarded June 20, 2018)Well that didn't take long, the FH isn't even certified yet. I bet the $130M price was very competitive. I wonder if the mission requirements required ULA to bid a DIVH or a Atlas-V with multiple SRB's?
https://twitter.com/jeff_foust/status/1009912347362844672?s=19@jeff_foustSpaceX has won a $130M contract from the US Air Force to launch the AFSPC-52 mission on a Falcon Heavy: https://t.co/UC6wV436GWQuoteAIR FORCESpace Exploration Technologies Corp. (SpaceX), Hawthorne, California, has been awarded a $130,000,000 firm-fixed-price contract, for launch services to deliver the Air Force Space Command-52 satellite to its intended orbit. This launch service contract will include launch vehicle production and mission, as well as integration, launch operations and spaceflight worthiness activities. Work will be performed in Hawthorne, California; Kennedy Space Center, Florida; and McGregor, Texas, and is expected to be completed by September 2020. This award is the result of a competitive acquisition, and two proposals were received. Fiscal 2018 space procurement funds in the amount of $130,000,000 will be obligated at the time of award. The Contracting Division, Launch Systems Enterprise Directorate, Space and Missile Systems Center, Los Angeles Air Force Base, California, is the contracting activity (FA8811-18-C-0003). (Awarded June 20, 2018)
Have to admit to some surprise that the Telstar 19 going up tonight is 7000 kg and larger than FH’s Arabsat 6. The FH seems to have less and less market, currently. Which is a shame.
Quote from: wannamoonbase on 07/21/2018 04:28 pmHave to admit to some surprise that the Telstar 19 going up tonight is 7000 kg and larger than FH’s Arabsat 6. The FH seems to have less and less market, currently. Which is a shame. FH could give it a much better orbit for a not much higher price.