SpaceX And/Or Rocketry In General

archae86
archae86
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The estimate issued at 1200

The estimate issued at 1200 UTC today gave a 40% chance of acceptable weather, with the primary concerns of violation in this case listed as "Flight through Precipitation, Thick Cloud Layer Rule, Cumulus Cloud Rule".

Anonymous

at present solid low ceiling

oops duplicate post deleted.

archae86
archae86
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While not the next official

While not the next official release, the weather folks at today's press conference upped the odds of acceptable level to 60% from the 40% most recent official release.

Anonymous

archae86 wrote: While not

archae86 wrote:

While not the next official release, the weather folks at today's press conference upped the odds of acceptable level to 60% from the 40% most recent official release.

local meteorologists are predicting rain through Saturday.  Looking out the window conditions appear better than yesterday.  But will they hold?   Conditions for this launch must be perfect or they won't go.  We do not want another Apollo 1 incident in which we lost an entire crew.  Better to wait then cut corners just to satisfy the accountants.   

archae86
archae86
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The official Launch Mission

The official Launch Mission Execution Forecast daily update came out at 1200 UTC (that is a bit over an hour ago as I post) and shows 60% chance of meeting all constraints for the primary launch window on May 27, and 70% chance for the first backup window on May 30.

The current list of primary violation concerns for May 27 is: Flight through Precipitation, Anvil Cloud Rule, and Cumulus Cloud Rule.

The concern list is the same for the May 30 opportunity.

They don't yet post a prediction for the May 31 window, which was the second backup last time I saw an update.

archae86
archae86
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42 minutes to launch, if it

42 minutes to launch, if it happens.

Weather is till questionable.  But looks good enough that they are currently nearly at the point of loading the (chilled) propellants).  Once that starts, they are truly locked to launch at a particular time--so from there it is abort or go.

 

 

archae86
archae86
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Apart from the chilled

Apart from the chilled propellant limitation, today was a zero-width window.

They just now aborted today's attempt.

Weather limitations.  

The one I heard was described as "field mill', which has to do with lightning risk posed by the weather condition.

It was a very close call.  Had there been the option to delay by ten minutes, probably the weather criteria would have permitted the launch.

(but it would not have been in position for meeting the ISS).

Better luck three days from now.

archae86
archae86
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On May 25, 2020, Virgin Orbit

On May 25, 2020, Virgin Orbit attempted their first orbital launch.

To those familiar with Pegasus, the basic system configuration has some similar elements.  In this case, a repurposed Boeing 747-400 carried a liquid-fueled rocket stage to level flight a bit above 30,000 feet, then accelerated to near red line level speed and pitched up, dropping the rocket a few thousand feet higher, and pointing up at a considerable angle (this time about 30 degrees!!)

The pitchup, at least to this degree, was not a feature of Pegasus operations, which instead had to provide a considerable wing and waste delta-V turning the velocity vector up enough to avoid burning too much fuel pushing a tunnel through medium altitude air.

Something went wrong, and thrust was terminated after about four seconds of engine burn.  The engine neither exploded nor was it commanded to shut down.  The termination was a malfunction, cause under investigation.

To their credit, the video Virgin Orbit has posted on Youtube has appreciable detail, including pretty good views of the drop and initiation of burn.  

I think you'll find the video worth a watch.  Yes, there is some PR in it, and more closeup seconds of various members of their team than of the drop and ignition, but I think it is well worth the two minutes to watch it.

If you adjust the viewing settings, quite high resolutions are available.  The ground material in particular was recorded with excellent actual resolution, so that watching it full screen at 1440p was a treat for me.

 

mikey
mikey
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archae86 wrote: Apart from

archae86 wrote:

Apart from the chilled propellant limitation, today was a zero-width window.

They just now aborted today's attempt.

Weather limitations.  

The one I heard was described as "field mill', which has to do with lightning risk posed by the weather condition.

It was a very close call.  Had there been the option to delay by ten minutes, probably the weather criteria would have permitted the launch.

(but it would not have been in position for meeting the ISS).

Better luck three days from now.

NatGeo Channel last night said 2pm Saturday will be the next try to launch the SpaceX guys, they didn't say EST or PST.

Mike Hewson
Mike Hewson
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A field mill is a gadget that

A field mill is a gadget that measures static electric field strength, giving so and so volts per metre. The higher that goes the more chance of a discharge to equilibrate ie. lightning.

Cheers, Mike.

 

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

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