Author Topic: SpaceX Falcon 9 : Telstar 19 Vantage : July 22, 2018 - DISCUSSION (Read 70437 times)

envy887 · « **Reply #40 on:** 07/21/2018 08:44 pm »

Quote from: Alexphysics on 07/21/2018 08:31 pm

Perigee is usually at LEO, usually high up at least above 200km, high enough for the second stage to be in that orbit for a few months at least. No reason to think that this particular mission will have a lower perigee than others, it will be as normal as usual, what's going to be lower than usual will probably be the apogee, but that doesn't affect to the rate of decay of the orbit (Well, technically it affects, but because a lower apogee means a shorter orbital period so the second stage will pass more times through the perigee in less time, but it will also pass through the perigee at a lower velocity, so who knows if it really affects it in the end or not).

Perigee altitude has a HUGE effect on the decay rate. The atmosphere is very non-linear in density vs altitude, so a slightly lower perigee greatly increases drag.

Alexphysics · « **Reply #41 on:** 07/21/2018 09:08 pm »

I was talking about the apogee affecting the decay rate, not perigee. I said about the perigee that we shouldn't expect this to be anything special at all and that it's usually above 200km. Second stages usually tend to stay for months in GTO even with perigees as low as that altitude, it's not that complex to understand I guess.

envy887 · « **Reply #42 on:** 07/21/2018 10:14 pm »

Quote from: Alexphysics on 07/21/2018 09:08 pm

I was talking about the apogee affecting the decay rate, not perigee. I said about the perigee that we shouldn't expect this to be anything special at all and that it's usually above 200km. Second stages usually tend to stay for months in GTO even with perigees as low as that altitude, it's not that complex to understand I guess.

Hah yeah I completely misread that. You're right.

abaddon · « **Reply #43 on:** 07/21/2018 10:36 pm »

IIRC the first Block 5 launch used a Block 4 flight profile for S2 (not utilizing the extra thrust). Presumably this launch will be using full rated thrust on both S1and S2 to get this bird as close to a normal GTO as possible. Will be interesting to compare!

wannamoonbase · « **Reply #44 on:** 07/22/2018 04:40 am »

Quote from: abaddon on 07/21/2018 10:36 pm

IIRC the first Block 5 launch used a Block 4 flight profile for S2 (not utilizing the extra thrust). Presumably this launch will be using full rated thrust on both S1and S2 to get this bird as close to a normal GTO as possible. Will be interesting to compare!

Agreed on all counts. A full Block 5 profile will be very fun to watch. And we can get a new baseline.

mtakala24 · « **Reply #45 on:** 07/22/2018 05:35 am »

SpaceX has still not publicly made the webcast link available, it is a private youtube link.

Perhaps this is to prevent the large number of rebroadcasters stealing their content? Dunno.

Lars-J · « **Reply #46 on:** 07/22/2018 05:37 am »

Quote from: mtakala24 on 07/22/2018 05:35 am

SpaceX has still not publicly made the webcast link available, it is a private youtube link.

Is anyone going to share it?

mtakala24 · « **Reply #47 on:** 07/22/2018 05:37 am »

The link is on the page two of the live thread.

Tomness · « **Reply #48 on:** 07/22/2018 05:38 am »

Quote from: Lars-J on 07/22/2018 05:37 am

Quote from: mtakala24 on 07/22/2018 05:35 am
SpaceX has still not publicly made the webcast link available, it is a private youtube link.

Is anyone going to share it?

Its in the update thread.
Updated:

mtakala24 · « **Reply #49 on:** 07/22/2018 05:42 am »

Now it is also publicly on YouTube.

Halidon · « **Reply #50 on:** 07/22/2018 06:03 am »

Will never not be amazed when the feed comes back and the stage is just sitting there.

Tomness · « **Reply #51 on:** 07/22/2018 06:03 am »

Quote from: Chris Bergin on 07/22/2018 06:00 am

Booster is back

Right in the bullseye!

LouScheffer · « **Reply #52 on:** 07/22/2018 06:08 am »

First stage cutoff was at 8170 km/hr = 2270 m/s.

This is exactly what we've seen on previous GTO with recovery missions. So no big performance boost for block 5.

Tomness · « **Reply #53 on:** 07/22/2018 06:10 am »

Quote from: ChrisGebhardt on 07/22/2018 06:01 am

Interesting. The calls were very clear over the loop that the F9 had landed safely, yet webcast host seemed very uncertain if a landing had occurred.

IMO Webhosts arent listing to Launch Net anymore & either taking queues from teleprompter or Web Stream Director.

Pete · « **Reply #54 on:** 07/22/2018 06:10 am »

Quote from: LouScheffer on 07/22/2018 06:08 am

First stage cutoff was at 8170 km/hr = 2270 m/s.

This is exactly what we've seen on previous GTO with recovery missions. So no big performance boost for block 5.

You don't consider the fact that they did this with a payload in excess of SEVEN TONS, as significant?

dasmoth · « **Reply #55 on:** 07/22/2018 06:11 am »

Has anyone been tracking entry burn times? That one seemed really short to me. Makes sense, given the heavy payload — but seems like they might still be pushing the “how hot can you go?” boundaries.

M.E.T. · « **Reply #56 on:** 07/22/2018 06:11 am »

Am I misremembering, or is MECO normally at around 2.24, whereas today it was about 10 seconds later at 2.34? Is there any significance to this, as in a correlation to increased peformance, or is this an optional cutoff point based on mission profile?

Lars-J · « **Reply #57 on:** 07/22/2018 06:16 am »

Looks like SpaceX attached the 2nd stage cameras much better now. Very little camera shake compared to previous missions.

toruonu · « **Reply #58 on:** 07/22/2018 06:20 am »

What's with the silence ... and no S2 engine cutoff nor is there any new telemetry it looks like (the altitude should have started to increase)

edit: looks like a comms issue, now updating and all fine.

Halidon · « **Reply #59 on:** 07/22/2018 06:24 am »

Little bit of tumble on the payload?