Author Topic: SpaceX Falcon 9 : GovSat-1 (SES-16) : Jan 31. 2018 - Discussion (Read 213364 times)

macpacheco · « **Reply #100 on:** 01/30/2018 01:04 am »

I wouldn't be surprised if Elon sends his jet up an hour before launch to find out if there's an actual wind shear rather than look just at the high level wind speeds.
The problem isn't the intensity of winds, but how fast they jump.
If there's no big jump, but rather a more smooth increase, then its ok.
Maybe the weather baloon is just as good, measuring maximum acceleration on the way up. Very different from simply looking at the winds.

John Alan · « **Reply #101 on:** 01/30/2018 03:03 am »

The issue in question and concern per the AF report is LIFTOFF winds...

Gusting to 30mph out of the North... $:-\$

Rockets right after liftoff, tend to drift downwind till they get some speed going and can steer...

There was only light shear forecasted looking at other weather sources... a non issue IMHO...

Grandpa to Two · « **Reply #102 on:** 01/30/2018 03:51 am »

Here are the forecasted winds from the Ventusky app. Set for the Cape but note the time is Pacific Time. Wind speeds are in knots with altitudes are in the upper right corner. I removed the wind direction from the 9000m shot so the speeds can be seen the wind direction is due east.

ChrisGebhardt · « **Reply #103 on:** 01/30/2018 09:47 am »

Quote from: John Alan on 01/30/2018 03:03 am

The issue in question and concern per the AF report is LIFTOFF winds...

Gusting to 30mph out of the North... $:-\$

Rockets right after liftoff, tend to drift downwind till they get some speed going and can steer...

There was only light shear forecasted looking at other weather sources... a non issue IMHO...

That's not what we're discussing. As the discussion has stated, there is an upper level wind component that is NOT accounted for in the official AF weather prediction.

RocketLover0119 · « **Reply #104 on:** 01/30/2018 01:28 pm »

Any word if Falcon is vertical yet?

IanThePineapple · « **Reply #105 on:** 01/30/2018 02:10 pm »

Well, it has legs and fins.

The patch did not lie

Also, interesting fairing design. Doesn't even mention SES.

cscott · « **Reply #106 on:** 01/30/2018 02:21 pm »

Why does it have legs?!

Ob. Crazy Theory: test of block 5 leg design, perhaps including early deploy as drag brakes? (That would be the part they'd be interested in testing, presumably; it would be odd to need to test actuation otherwise and they can't test landing loads or post-landing stability when doing a water landing.)

IanThePineapple · « **Reply #107 on:** 01/30/2018 02:22 pm »

Quote from: cscott on 01/30/2018 02:21 pm

Why does it have legs?!

Ob. Crazy Theory: test of block 5 leg design, perhaps including early deploy as drag brakes? (That would be the part they'd be interested in testing, presumably; it would be odd to need to test actuation otherwise and they can't test landing loads or post-landing stability when doing a water landing.)

Why not keep testing landing legs, and get rid of the old Block 3 legs in a peaceful manner.

RocketLover0119 · « **Reply #108 on:** 01/30/2018 02:23 pm »

We've got ourselves another sooty McSooterson.

cscott · « **Reply #109 on:** 01/30/2018 02:27 pm »

Quote from: IanThePineapple on 01/30/2018 02:22 pm

Quote from: cscott on 01/30/2018 02:21 pm
Why does it have legs?!

Ob. Crazy Theory: test of block 5 leg design, perhaps including early deploy as drag brakes? (That would be the part they'd be interested in testing, presumably; it would be odd to need to test actuation otherwise and they can't test landing loads or post-landing stability when doing a water landing.)

Why not keep testing landing legs, and get rid of the old Block 3 legs in a peaceful manner.

But what is there left to test?

I mean, obviously if the legs are installed they are there for some test or other, since they won't be useful for actually landing the stage.

The question is: what are they testing?

And if they are reused block 3 legs, what data could they get that would still be applicable to the new block 5 design?

(This is an honest question, not an implication that there is no such data or worthwhile test program.)

Johnnyhinbos · « **Reply #110 on:** 01/30/2018 02:27 pm »

Quote from: IanThePineapple on 01/30/2018 02:22 pm

Quote from: cscott on 01/30/2018 02:21 pm
Why does it have legs?!

Ob. Crazy Theory: test of block 5 leg design, perhaps including early deploy as drag brakes? (That would be the part they'd be interested in testing, presumably; it would be odd to need to test actuation otherwise and they can't test landing loads or post-landing stability when doing a water landing.)

Why not keep testing landing legs, and get rid of the old Block 3 legs in a peaceful manner.

- Installing legs takes time and resources = $$$
- Legs add mass that takes away from performance
- Legs are a point of failure, no matter how small
- Non-Block 5 legs are pretty well understood by now.
- Rumor has it the Block 5 legs are quite different and immediately noticeable.

This one is odd...

cscott · « **Reply #111 on:** 01/30/2018 02:32 pm »

Quote from: Demidrol on 01/30/2018 02:28 pm

Is the reentry phase different with/without legs attached?

The previous expendable flight (from Vandenberg) had grid fins but not legs. That seemed to imply that grid fins are a core part of the reentry program (or at least the test program), but not legs.

But maybe the previous flight displayed some variance which the engineers traced to the lack of legs, so now they are going to repeat the test in full fidelity flight configuration?

eeergo · « **Reply #112 on:** 01/30/2018 02:32 pm »

Also somewhat interestingly, the racetrack and its associated interstage fairing is left unpainted (or changed to a new material?) black.

Rocket Science · « **Reply #113 on:** 01/30/2018 02:35 pm »

Quote from: RocketLover0119 on 01/30/2018 02:23 pm

We've got ourselves another sooty McSooterson.

You think they would have gave her a wash out of respect for the "royals" being present... So unseemly...

MechE31 · « **Reply #114 on:** 01/30/2018 02:38 pm »

My guess on the legs is that they planned to recover this one, but given how the dates worked out, they prioritized recovering FH.

cscott · « **Reply #115 on:** 01/30/2018 02:45 pm »

Quote from: MechE31 on 01/30/2018 02:38 pm

My guess on the legs is that they planned to recover this one, but given how the dates worked out, they prioritized recovering FH.

Removing the legs is less than a day's work, though: we see them do it every time they recover a stage. Why throw the $$$ away?

MechE31 · « **Reply #116 on:** 01/30/2018 02:51 pm »

Quote from: cscott on 01/30/2018 02:45 pm

Quote from: MechE31 on 01/30/2018 02:38 pm
My guess on the legs is that they planned to recover this one, but given how the dates worked out, they prioritized recovering FH.
Removing the legs is less than a day's work, though: we see them do it every time they recover a stage. Why throw the $$$ away?

The decision was probably made before a FH launch date was firm and by the time the date was set, the legs were already on the vehicle.

How do you deal with the fittings, attach points and other penetrations through the tank that are now exposed? It's probably cheaper, easier and less risky to fly the known configuration than to try and scramble to reconfigure the rocket.

First Mate Rummey · « **Reply #117 on:** 01/30/2018 02:55 pm »

Quote from: MechE31 on 01/30/2018 02:38 pm

My guess on the legs is that they planned to recover this one, but given how the dates worked out, they prioritized recovering FH.

If this is true, then they would give very few value to the recovered core. They could just have postponed FH, and I wouldn't be surprised if it will get postponed anyway as happened to the static fire.

RocketLover0119 · « **Reply #118 on:** 01/30/2018 02:59 pm »

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

Quote from: cscott on 01/30/2018 02:45 pm

Quote from: MechE31 on 01/30/2018 02:38 pm
My guess on the legs is that they planned to recover this one, but given how the dates worked out, they prioritized recovering FH.
Removing the legs is less than a day's work, though: we see them do it every time they recover a stage. Why throw the $$$ away?

Prettz · « **Reply #119 on:** 01/30/2018 03:17 pm »

Quote from: RocketLover0119 on 01/30/2018 02:59 pm

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?