Author Topic: SpaceX Falcon Mission Simulations  (Read 16449 times)

Offline manoweb

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Re: SpaceX Falcon Mission Simulations
« Reply #80 on: 05/17/2017 07:39 PM »
Yeah so far I've done NROL-76 (first stage), Inmarsat-5, SES-10. I can do Echostar-23. I think I will do all launches in 2017 now that I have built my tool. I will include also the timestamps

Online OneSpeed

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Re: SpaceX Falcon Mission Simulations
« Reply #81 on: 06/05/2017 01:51 PM »
Here is a sim of the CRS-11 first stage profile.

Points of interest include:
1. The booster appears to launch at slightly less than full throttle (84% of the published block 5 figures) before throttling up to 91% of block 5 after about 5 seconds.
2. What appears to be a minimum thrust single engine ullage burn starting half way through the flip at 2:40.
3. A 1:3:1 engine entry burn at 6:10.


Offline hkultala

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Re: SpaceX Falcon Mission Simulations
« Reply #82 on: 06/05/2017 02:54 PM »
Highest throttle at boostback burn.

So they do not want to risk the payload / want to maximize reliability when stage 2 and payload are attached by using it with "full throttle", and are only using full throttle for boostback. 

(but propably they would use full throttle if they would lose one engine, to compensate for the loss of thrust)

And high T/W is very important for the boostback burn, as it's flying away from the launch & landing site and the faster the boostback burn is, the shorter distance it has to travel.

« Last Edit: 06/05/2017 02:57 PM by hkultala »

Offline deruch

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Re: SpaceX Falcon Mission Simulations
« Reply #83 on: 06/08/2017 04:28 AM »
Points of interest include:

2. What appears to be a minimum thrust single engine ullage burn starting half way through the flip at 2:40.


I think this is related to how fast they are trying to do the flips now.  With all the authority of the burning engine, they can afford to do a higher rotational speed flip and still ensure that they can maintain enough prop at the bottom of the tanks and that they can handle any off-axis impulses from any sloshing.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online OneSpeed

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Re: SpaceX Falcon Mission Simulations
« Reply #84 on: 07/01/2017 08:19 AM »
Here is a sim of BulgariaSat-1. The telemetry for this mission and the next is not complete, but there are similar missions that help fill in the gaps, in this case SES-10.

This mission was of course most notable for the first coast-to-coast re-use of a booster, but the profile had a couple of points of interest as well.

1. As per SES-10, the high AoA of the entire rocket from the 1:40 mark. Does anyone know why this manoeuvre has only been used for these particular GTO satellite missions?

2. The initial S2 orbit is about 160 x 480kms, and the GTO burn occurs at about 250kms. I've seen it suggested that ideally such a burn should occur at perigee, where velocity is highest, minimising the ΔV requirement. Does anyone have any insight into why the GTO burn was done this particular way?

3. Elon Musk: 'Rocket was suddenly slammed sideways right before landing. Heavy gust or something malfunctioned onboard. Reviewing telemetry.' I've attempted to model the effect of a heavy gust at the 8:30 mark, at about 400m altitude.


Offline Rebel44

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Re: SpaceX Falcon Mission Simulations
« Reply #85 on: 07/06/2017 08:31 PM »
Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GEO (with some reserve for sending 2nd stage to graveyard orbit)
« Last Edit: 07/06/2017 08:57 PM by Rebel44 »

Offline jpo234

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Re: SpaceX Falcon Mission Simulations
« Reply #86 on: 07/06/2017 08:32 PM »
Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GTO (with some reserve for sending 2nd stage to graveyard orbit)
There are no available data on Block 5 right now.

Offline Rebel44

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Re: SpaceX Falcon Mission Simulations
« Reply #87 on: 07/06/2017 08:55 PM »
Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GTO (with some reserve for sending 2nd stage to graveyard orbit)
There are no available data on Block 5 right now.

There is posted performance on SpaceX website for LEO and GTO (and few others) which based on what we know appears to be expected block 5 (expendable) performance
22 800 kg to LEO
 8 300 kg to GTO

Even estimated GEO performance based on block 3 performance would be appreciated.
« Last Edit: 07/06/2017 08:56 PM by Rebel44 »

Offline envy887

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Re: SpaceX Falcon Mission Simulations
« Reply #88 on: 07/06/2017 08:56 PM »
...
There are no available data on Block 5 right now.

The listed performance on SpaceX website is for a Block 5 launch. Block 3/4 will be retired long before anyone buying a launch right now gets to the pad.

Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GTO (with some reserve for sending 2nd stage to graveyard orbit)

Expendable Block 3/4 mix to GTO is what you just saw yesterday: 6781 kg to GTO, slightly supersync. There's no need for a GTO graveyard orbit, the upper stages decay quickly. Expendable block 5 is supposed to ptu 8300 kg to GTO.

If you mean direct to GSO, then my my calculations Block 3/4 will put about 1200 2100kg and Block 5 about 4000 3000 kg direct to GSO. The spacecraft RCS can probably handle the move to graveyard orbit, it's a >1 second burn on a 38% throttled MVac.

Edit: poor recollection of previous calculations, corrected.
« Last Edit: 07/06/2017 09:09 PM by envy887 »

Offline Rebel44

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Re: SpaceX Falcon Mission Simulations
« Reply #89 on: 07/06/2017 08:58 PM »

Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GTO (with some reserve for sending 2nd stage to graveyard orbit)

If you mean direct to GSO, then my my calculations Block 3/4 will put about 1200 kg and Block 5 about 4000 kg direct to GSO. The spacecraft RCS can probably handle the move to graveyard orbit, it's a >1 second burn on a 38% throttled MVac.

Yeah, I mixed up GTO and GEO
Thanks for the estimate!

Offline envy887

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Re: SpaceX Falcon Mission Simulations
« Reply #90 on: 07/06/2017 09:08 PM »

Can someone here please calculate from available data what is performance of expendable F9 1.2 block 3 and expendable F9 1.2 block 5 to GTO (with some reserve for sending 2nd stage to graveyard orbit)

If you mean direct to GSO, then my my calculations Block 3/4 will put about 1200 kg and Block 5 about 4000 kg direct to GSO. The spacecraft RCS can probably handle the move to graveyard orbit, it's a >1 second burn on a 38% throttled MVac.

Yeah, I mixed up GTO and GEO
Thanks for the estimate!

Certainly, but I'm afraid I recalled wrong above - I was calculating in pounds and for FH a few days ago :D

Rechecking my math, Block 3/4 gets 6800 kg to GTO, with a stage mass of 4500 kg and Isp of 348, that is about 2100 kg to GSO.
Block 5 gets 8300 kg to GTO, with same stage and Isp that is about 3000 kg to GSO.

LOX boiloff will reduce this somewhat, but I don't have a good way to estimate that.

Online OneSpeed

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Re: SpaceX Falcon Mission Simulations
« Reply #91 on: 07/09/2017 04:52 AM »
Here is a 'compari-sim' between the Inmarsat-5 F4 and Intelsat-35e mission profiles. They are very similar in many ways, but:

1. The relative effect of the S1 throttle and shutdown profiles is interesting to view.
2. The sims generated the following post SECO-2 S2 masses, with and without a 200Kg allowance for plane change:
MissionNo plane changeWith plane change
Iridium-5 F45.5mT5.3mT
Intelsat-35e5.3mT5.1mT
I'd assumed both missions were burn to depletion, but perhaps some of the difference can be attributed to a variation in fuel densification between the missions?

« Last Edit: 07/09/2017 06:03 AM by OneSpeed »

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