Author Topic: Falcon Heavy performance curves for various recovery strategies  (Read 3416 times)

Offline LouScheffer

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The NASA launch performance estimator has only two Falcon Heavy variants - all stages recovered (side RTLS, center ASDS) and all stages expended.   But there are two other variants that have been used, or will be used soon - RTLS with center expended, and ASDS sides with center expended.  A fifth configuration not considered here is full recovery with ASDS sides and ASDS core.  However this requires three droneships, or landing both sides on a single droneship.  Neither seems likely.

Now we have USSF-67 (RTLS sides, core expended) and ViaSat (all expended).  Since the center stage is the same for both mission types, for the same payload masses, it will provide the same delta-V (minus some small remaining differences in effects such as gravity loss).  So the difference in performance boils down to the speed at second stage startup.  With ViaSat, staging was at 17078 km/hr or 4743 m/s.  For USSF-67, staging was at 14504 km/hr, or 4028 m/s.  The difference is 715 m/s, but USSF-67 was lighter (3700 kg vs 6700 kg).  Payload mass affects booster performance by roughly 12 m/s per tonne.  However, not all this increased performance would be available to USSF-67 since any additional delta-V will need to be cancelled for boostback.  So maybe 25 m/s might be attributable to the differing mass, so the difference between RTLS and expended side boosters is about 740 m/s.

Now we can translate the fully expended performance (from the NASA Launch Performance site) to the RTLS sides, core expended, performance.  From the site, fully expended can push 6000 kg to C3=44.5.  From this, we find the speed at 185 km altitude (12888 m/s).  We subtract 740 m/s to account for RTLS sides, then find the new C3=26.0.  Thus an RLTS sides, core expended, can achieve C3=26 with a 6000 kg payload.  We do the same for other masses of payload.

Payload   C3(exp) C3(RLTS)
10000 kg    20.6     3.5
 6000 kg    44.5    26.0
 4000 kg    61.0    41.6
 2000 kg    82.4    61.8

Then we draw these points (open circles) on the mass vs C3 plot, draw a smooth-ish curve through them, and we have the RTLS sides/core expended performance.

Offline edkyle99

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Psyche and Jupiter 3 launches add to the data.  Not particularly impressive (yet) compared to the catalog capability claims.

Launches of "record", as I see them.

All cores "recovered"[1]:  FH-2, Arabsat 6A, 6465 kg to GTO+ (327x89815 km x 22.96 deg)

Center core expended:   FH-7, Jupiter 3, 9200 kg to GTO+ (8000x35504  km x 10.39 deg)
                                       FH-5, USSF 67, ~4000 kg to GEO
                                       FH-8, Psyche, 2747 kg to HCO (c3=15km2/sec2)

All cores expended:  FH-6, ViaSat 3, 6740 kg to GEO (Satellite Antenna Deploy Failed)

[1] Core B1055.1 landed OCISLY, but was subsequently lost overboard.

 - Ed Kyle
« Last Edit: 10/14/2023 02:33 pm by edkyle99 »

Offline abaddon

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Would be interesting to see other launchers e.g. Delta IV Heavy’s most demanding launches vs theoretical max perf.  Of course some of that data is likely classified, but there are a few launches like the first Orion that might tell us something.

Offline wannamoonbase

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Thanks for posting.  I'm sure I'm not the only one that thinks about ways to get the most out of FH.

I have not given up on seeing a FH core recovered one day.  Although very unlikely.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline Herb Schaltegger

Thanks for posting.  I'm sure I'm not the only one that thinks about ways to get the most out of FH.

I have not given up on seeing a FH core recovered one day.  Although very unlikely.

Well, cool as it would be, from what I’ve heard (from someone well-placed to know), SpaceX is basically done trying to make it work. The future - whenever and to the extent that future ever arrives - is Starship with massive payload and full two-stage reusability. FH will remain for the next however many years if only to fly out NatSec missions, but the economics don’t seem to warrant “wasting” further funds on Center core recoverability and reuse given the time/money/effort still remaining to make Starship work and the promise if it does.
Ad astra per aspirin ...

Offline Jim

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Thanks for posting.  I'm sure I'm not the only one that thinks about ways to get the most out of FH.

I have not given up on seeing a FH core recovered one day.  Although very unlikely.

Well, cool as it would be, from what I’ve heard (from someone well-placed to know), SpaceX is basically done trying to make it work. The future - whenever and to the extent that future ever arrives - is Starship with massive payload and full two-stage reusability. FH will remain for the next however many years if only to fly out NatSec missions, but the economics don’t seem to warrant “wasting” further funds on Center core recoverability and reuse given the time/money/effort still remaining to make Starship work and the promise if it does.

Exactly.  Too different from standard Falcon as it is and would have to be modified more for recovery

Offline gtae07

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Thanks for posting.  I'm sure I'm not the only one that thinks about ways to get the most out of FH.

I have not given up on seeing a FH core recovered one day.  Although very unlikely.

Well, cool as it would be, from what I’ve heard (from someone well-placed to know), SpaceX is basically done trying to make it work. The future - whenever and to the extent that future ever arrives - is Starship with massive payload and full two-stage reusability. FH will remain for the next however many years if only to fly out NatSec missions, but the economics don’t seem to warrant “wasting” further funds on Center core recoverability and reuse given the time/money/effort still remaining to make Starship work and the promise if it does.

I'd also suspect that the gap between "expended F9" and "full recovery FH" is pretty narrow.  If you can't make the former work for your payload, you'd probably rather just pay the fee for a booster RTLS expended core FH and get lots more mass budget for equipment or propellant, or get a better insertion orbit.

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