Launch News SpaceX Falcon 9 v1.2 with SES-9 March 4 2016

[GLS]

It's not the absolute speed of the air, but the rate of change of the speed. A significant shear can put large bending moments on the rocket.

This.
The rocket has to turn its nose to the wind to keep going in the direction it wants, and large changes of wind direction/speed require large and fast attitude corrections, and well... the hardware has its limitations.

---------- Post added at 01:44 AM ---------- Previous post was at 01:37 AM ----------

I'd love to find a better source for the launch criteria for upper level winds and windshear. This is as good as I can find: https://www.nasa.gov/pdf/649911main_051612_falcon9_weather_criteria.pdf ... and it just says not to launch through upper level conditions containing wind shear... without any quantification. Frustrating really.

The criteria probably is the result of a simulated launch with those wind conditions: does the structure survive and are guidance targets met?

 

[C3PO]

It's not the absolute speed of the air, but the rate of change of the speed. A significant shear can put large bending moments on the rocket.

Wind shear bent the STS-51L SRB enough to dislodge the aluminium-oxide that had plugged the failed O-rings at lift-off.

 

[Urwumpe]

Wind shear bent the STS-51L SRB enough to dislodge the aluminium-oxide that had plugged the failed O-rings at lift-off.

Must not have been a strong bending moment to achieve this. But there was a significant one that made it almost guaranteed during flight.

The biggest problem that I see personally there: It is a rocket that should land on a barge. And just a bit of wind is imposing too much structural loads on it (close to max Q, though) to endanger it. Flying towards the barge and landing there should put much higher loads on the rocket than this.

 

[Lmoy]

Flying towards the barge and landing there should put much higher loads on the rocket than this.

The difference though is that if the rocket's structure fails on landing, it's no big deal. If it fails on ascent, that's a very serious problem and then we won't even have an SES-9 satellite to repeatedly not launch anymore. I imagine that there's certain safety margins that they're sticking within. So say the structure is rated to survive 110% of expected loads on descent, which translates to 150% of expected loads on ascent with Tuesday's wind shear, but for safety reasons they won't launch until the wind shear is low enough that the structure will survive 200% of expected loads on ascent. At least, that's what I'm assuming their process is.

 

[ADSWNJ]

Looking at telemetry from an earlier launch, I see that Max Q is in that 20-20km altitude, at around 75s to 100s into the flight. Probably not the best place to have heavy vertical windshear.

Incidentally - if you want to see amazing view of this mid-level wind storm and the predictions for the next 2-3 days, then go to PivotalWeather.com here, and run the animation loops for the 200mb and 300mb Height, Wind on the NAM. (For launch day, use the HRRR model instead for shorter range / more detail).

 

[dman]

250 km/h? :shrug:

High altitude jet stream

During WWII actually had B-29s being pushed BACKWARDS by such winds...!

 

[ADSWNJ]

High altitude jet stream

During WWII actually had B-29s being pushed BACKWARDS by such winds...!

Only in groundspeed! Actually, if this were the case, the B-29 must not stray into putting the wind on the tail (e.g. circling), or it would stall.

 

[Urwumpe]

High altitude jet stream

During WWII actually had B-29s being pushed BACKWARDS by such winds...!

Its less than the top wind speed measured atop of the Brocken mountain, which was 263 km/h in about 1000 m altitude.

(Mount Washington actually even reached 376 km/h wind once)

 

[ADSWNJ]

300mb and 200mb winds at Friday's launchtime are 65kts and 85kts respectively. Much better then last Tuesday. Saturday's winds are 70kts and 75kts respectively. Hopefully green again.

 

[Andy44]

nvm...

 

[Lmoy]

Live stream has started, they said everything is looking good for launch, so maybe we'll finally get to see it today.

 

[tl8]

Landing was off to the side. Didn't look like it survived

 

[Hlynkacg]

MECO!

Second stage is in LEO w/Payload, waiting for GTO transfer burn, no word on first stage yet.

 

[ADSWNJ]

Very smooth countdown & launch this time, and it looks like a nominal mission so far.

 

[Hlynkacg]

Payload separation Successful!

---------- Post added at 16:06 ---------- Previous post was at 16:09 ----------

Webcast is coming to a close. No word on the first stage so assume the worst.

 

[Donamy]

Payload separation Successful!

---------- Post added at 16:09 ---------- Previous post was at 16:09 ----------

Webcast is coming to a close. No word on the first stage so assume the worst.

Assume what was expected.

 

[Frilock]

Rocket landed hard on the droneship. Didn't expect this one to work (v hot reentry), but next flight has a good chance.

Elon via twitter.

 

[ADSWNJ]

Confirmation of RUD for stage 1 on or very near the drone ship.

 

[Frilock]

I never realized how QUIET Falcon launches are. I was just on the other side of the river and I couldn't hear ANYTHING.

 

[RisingFury]

Landing might have been bad, the mission succeeded.