Falcon 9 target orbit accuracy

[kirghizstan]

Has anyone looked at how accurate has F9 been with regards to target orbits relative to other current vehicles?

[Comga]

Has anyone looked at how accurate has F9 been with regards to target orbits relative to other current vehicles?

You can probably research this yourself on Jonathan's Space Page.
Dr. McDowell (our jcm!) may have this in a table somewhere but undoubtedly has the data.
It is probably in his Master Launch Log.

[EchoLogic]

I've done a few comparisons of the commercial sat launches for SpaceX, and they are noticeably getting more accurate. IIRC AsiaSat 6 was the most accurate so far. Orbcomm CEO was also impressed by the accuracy after the launch of OG2. The numbers are buried in a Reddit comment I made somewhere.

[metaphor]

The relative accuracy is not quite that clear from those numbers.  Achieving the same error at a higher apogee is much harder, assuming error is proportional to delta-v accuracy.  And the error scales higher than a linear function (for example, a 90 km margin at 90,000 km is harder to achieve than a 30 km margin at 30,000 km). 

Also, in the case of super-synchronous orbits, the Falcon 9 upper stage is lighter at burnout (since it has to go through more delta-v), and therefore it has higher thrust.  If the accuracy depends on the exact time the engine cuts off, this means that the same delta-t error will result in a higher delta-v error in those cases.

A third point is that the 80,000 km and 90,000 km apogees are suspiciously round numbers, from which I would think that the customer doesn't require very high accuracy.  The only thing an error in apogee would do for a super-synchronous orbit launch would be to slightly change the delta-v of the following perigee-raising burn.  In the case of a stationary transfer orbit, the apogee does have to be very close to 35,786 km, otherwise the satellite has to do an entirely new burn at a different place in its orbit to fix the apogee.

So I don't really see SpaceX getting more accurate in their launches as much as I see a geostationary transfer launch being both easier and more important to get accurate than a super-synchronous transfer launch.

[Carl G]

Thread title made descriptive. Only accurate references are welcome here, so don't link random social media, use accurate sites, like Jonathans.

[sheltonjr]

 I learned a lot reading the article on what the Soyuz rocket went through to be able to do the quick 6 hour transit to the station. It was mostly about accurate orbital insertion.

Will the current F9 with Dragon V2 orbital insertion accuracy good enough for Dragon to also do a quick transit to the ISS?

[Lar]

Thread title made descriptive. Only accurate references are welcome here, so don't link random social media, use accurate sites, like Jonathans.

As a note, without the release of official data by SpaceX themselves or their customer on exactly what they were trying for, there is a limit to how accurate an analysis can be. That said, I'm with Carl, let's use official data whereever possible. Orbital element sets, press releases from customers, and so forth, and failing that, let's go with the best of the rest, such as Jonathan's site...

[pericynthion]

Will the current F9 with Dragon V2 orbital insertion accuracy good enough for Dragon to also do a quick transit to the ISS?

I believe SpaceX have said that they intend to perform first-day rendezvous with crewed Dragon flights, so presumably yes.

[simonbp]

Are there any operational constrains that would prevent a first-day berthing for a CRS flight? IIRC the "climbing the ladder" procedure takes a lot longer than a crewed docking (judging by the speed of Soyuz approaches).

[Scylla]

Are there any operational constrains that would prevent a first-day berthing for a CRS flight? IIRC the "climbing the ladder" procedure takes a lot longer than a crewed docking (judging by the speed of Soyuz approaches).

Unless my memory is faulty, I believe this question has been covered elsewhere in these forums. The conclusion being that someone from SpaceX stated there were no operational constraints. The only limiting factor was ISS had to be in the right spot to make it possible, the same for Soyuz, and that some time in the future they would start doing same-day berthing.