SpaceX Falcon 9 : CRS-11 : June 3, 2017 : DISCUSSION

[king1999]

The 48-hour turnaround is because an experiment in the Dragon requires a cold pack changed out.

Source? I only heard about the mice. Never heard that they used cold pack but freezer.

[TrueBlueWitt]

I know it's been discussed many times that the launch window is instantaneous because considering F9 performance it doesn't have enough for a significant delay that would allow a scrub. However considering todays situation where the all go weather clearance would be <5 min after the current T-0 or for example if the lightning strike had been T-29:40 or similar they could reset to a few minute delay.

Considering that calculated F9 capabilities with the Block IV and what we guess as Block V could an F9 have a non-inst window for an ISS supply and if so by how much? Could it be enough for a 2-3 minute change i.e. todays situation or not?

The payload penalty for a non-instantaneous launch window isn't all that large.  Atlas V routinely uses a 30 minute window with Cygnus.  The issue is that the flight software has to be designed to support loading a (or at least selecting a preloaded) yaw steering profile at the last minute.

My guess it it has the performance for some window, if you want to fly expendable.. which they do not.

The question is, does Atlas V have launch times set at the very first second they can get there with yaw steer one direction.. then hold time is through the last moment they can get there using yaw steer the other way? or does it target optimal, and then only have the tail end of the window?

[whitelancer64]

The 48-hour turnaround is because an experiment in the Dragon requires a cold pack changed out.

Source? I only heard about the mice. Never heard that they used cold pack but freezer.

Some things that might require lower temperatures, but do not need to be frozen, would use a passive cooling system - i.e., a cold pack - for thermal control. Some also use re-freezable ice packs inside insulated "cold bags."

I imagine fresh food would be an example.

[cppetrie]

I know it's been discussed many times that the launch window is instantaneous because considering F9 performance it doesn't have enough for a significant delay that would allow a scrub. However considering todays situation where the all go weather clearance would be <5 min after the current T-0 or for example if the lightning strike had been T-29:40 or similar they could reset to a few minute delay.

Considering that calculated F9 capabilities with the Block IV and what we guess as Block V could an F9 have a non-inst window for an ISS supply and if so by how much? Could it be enough for a 2-3 minute change i.e. todays situation or not?

The payload penalty for a non-instantaneous launch window isn't all that large.  Atlas V routinely uses a 30 minute window with Cygnus.  The issue is that the flight software has to be designed to support loading a (or at least selecting a preloaded) yaw steering profile at the last minute.

My guess it it has the performance for some window, if you want to fly expendable.. which they do not.

The question is, does Atlas V have launch times set at the very first second they can get there with yaw steer one direction.. then hold time is through the last moment they can get there using yaw steer the other way? or does it target optimal, and then only have the tail end of the window?

From what I could tell from the last Cygnus launch, they have pre-programmed flight paths based on something like 5 minute intervals in the launch window. The start of the window is the optimal path and the window lasts for as many paths as the vehicle is capable of. The flight computer is told which program to use based on which T-0 gets used. At five minute intervals and a 30 minute launch window, they can support an additional 6 decreasingly optimal flight paths. They are all still instantaneous launch windows they just have several of them in quick succession. The fact that they don't sub-cool the propellants probably also makes this capability more doable since short delays in the launch won't have the same affect on propellant temps. Anybody that knows more please feel free to correct or confirm my understanding.

Edit: typo

[Sam Ho]

I know it's been discussed many times that the launch window is instantaneous because considering F9 performance it doesn't have enough for a significant delay that would allow a scrub. However considering todays situation where the all go weather clearance would be <5 min after the current T-0 or for example if the lightning strike had been T-29:40 or similar they could reset to a few minute delay.

Considering that calculated F9 capabilities with the Block IV and what we guess as Block V could an F9 have a non-inst window for an ISS supply and if so by how much? Could it be enough for a 2-3 minute change i.e. todays situation or not?

The payload penalty for a non-instantaneous launch window isn't all that large.  Atlas V routinely uses a 30 minute window with Cygnus.  The issue is that the flight software has to be designed to support loading a (or at least selecting a preloaded) yaw steering profile at the last minute.

My guess it it has the performance for some window, if you want to fly expendable.. which they do not.

The question is, does Atlas V have launch times set at the very first second they can get there with yaw steer one direction.. then hold time is through the last moment they can get there using yaw steer the other way? or does it target optimal, and then only have the tail end of the window?

From what I could tell from the last Cygnus launch, they have pre-programmed flight paths based on something like 5 minute intervals in the launch window. The start of the window is the optimal path and the window lasts for as many paths as the vehicle is capable of. The flight computer is told which program to use based on which T-0 gets used. At five minute intervals and a 30 minute launch window, they can support an additional 6 decreasingly optimal flight paths. They are all still instantaneous launch windows they just have several of them in quick succession. The fact that they don't sub-cool the propellants probably also makes this capability more doable since short delays in the launch won't have the same affect on propellant temps. Anybody that knows more please feel free to correct or confirm my understanding.

Edit: typo

The Atlas/Cygnus launches put the center of the launch window at the optimal time.  See this post by Newton_V (who works at ULA) discussing OA-6.

I don't suppose this launch happened at the lowest delta-v instant of the several instantaneous launch possibilities Atlas V provided?

Yes, the window open and close required more performance to steer back to the inertial plane (RAAN target).
Launching at window middle (and also optimal), would have not been as nail-biting on launch day.  Anomaly would have still happened, but much more performance would have been available.

[llanitedave]

I'm starting to get discouraged that they'll ever reach their desired launch cadence as unstable and unreliable as the Florida weather is.

[leetdan]

Calm down everybody, the summer convective pattern in Florida is nothing new.  Increased readiness will result in increased cadence regardless of weather.

[hans_ober]

I know it's been discussed many times that the launch window is instantaneous because considering F9 performance it doesn't have enough for a significant delay that would allow a scrub. However considering todays situation where the all go weather clearance would be <5 min after the current T-0 or for example if the lightning strike had been T-29:40 or similar they could reset to a few minute delay.

Considering that calculated F9 capabilities with the Block IV and what we guess as Block V could an F9 have a non-inst window for an ISS supply and if so by how much? Could it be enough for a 2-3 minute change i.e. todays situation or not?

The payload penalty for a non-instantaneous launch window isn't all that large.  Atlas V routinely uses a 30 minute window with Cygnus.  The issue is that the flight software has to be designed to support loading a (or at least selecting a preloaded) yaw steering profile at the last minute.

My guess it it has the performance for some window, if you want to fly expendable.. which they do not.

The question is, does Atlas V have launch times set at the very first second they can get there with yaw steer one direction.. then hold time is through the last moment they can get there using yaw steer the other way? or does it target optimal, and then only have the tail end of the window?

From what I could tell from the last Cygnus launch, they have pre-programmed flight paths based on something like 5 minute intervals in the launch window. The start of the window is the optimal path and the window lasts for as many paths as the vehicle is capable of. The flight computer is told which program to use based on which T-0 gets used. At five minute intervals and a 30 minute launch window, they can support an additional 6 decreasingly optimal flight paths. They are all still instantaneous launch windows they just have several of them in quick succession. The fact that they don't sub-cool the propellants probably also makes this capability more doable since short delays in the launch won't have the same affect on propellant temps. Anybody that knows more please feel free to correct or confirm my understanding.

Edit: typo

The Atlas/Cygnus launches put the center of the launch window at the optimal time.  See this post by Newton_V (who works at ULA) discussing OA-6.

I don't suppose this launch happened at the lowest delta-v instant of the several instantaneous launch possibilities Atlas V provided?

Yes, the window open and close required more performance to steer back to the inertial plane (RAAN target).
Launching at window middle (and also optimal), would have not been as nail-biting on launch day.  Anomaly would have still happened, but much more performance would have been available.

Atlas uses RAAN steering as far as I know. They've got the capability to calculate the plane they're going to end up in and steer accordingly in realtime. Like a realtime dogleg.

RAAN/dogleg does use extra vehicle performance, and I'm guessing it complicates things for SpaceX since they've probably gotta change landing programs too.

I think the optimal time performance wise is the middle of the window. Start and end use more performance, but ULA targets the start of the windows, since they've the performance and they try to get it off the pad ASAP.
Can't find a source, but ULA or Tory tweeted something about this during the early Atlas Cygnus launches, they even had a nice infographic (basic) showing the different launch paths to help people understand.

[butters]

Calm down everybody, the summer convective pattern in Florida is nothing new.  Increased readiness will result in increased cadence regardless of weather.

Only the African Congo has a higher frequency of lightning strikes than Central Florida. It is a pretty terrible location for a launch site in terms of weather, although obviously it has several other things going for it. Maintaining a two week cadence shouldn't be a problem, but pushing the cadence to multiple launches per week may be challenging for several months of the year at the Cape.

[manoweb]

Photos seem to suggest that this Falcon 9 is back to the Block 3 second stage, after two flights by Block 4 second stages.

That is what Mr. Hans said in the conference.

[macpacheco]

I'm starting to get discouraged that they'll ever reach their desired launch cadence as unstable and unreliable as the Florida weather is.

Wrong. SpaceX aims for launch cadence capability, if there are enough payloads and if the weather cooperates. Weather delays (and heavens forbid a stand down) are made up by having some spare launch capacity. A launch every 2 weeks now, a launch a week with LC39A+LC40 up and running.

A launch every day will never be sustainable 365 days a year, just not.

Even aircraft cannot fly in some days, and they have much higher tolerance to turbulence, wind shear, icing and other risk factors.

GTO launches are far easier to accomplish, as long as launch windows start no earlier than 11PM, ideally 1AM window openings.
Many days the weather looks downright crummy all day long, but after sunset it pours down and is ready to go after midnight, specially with a large launch window where you can time the launch with a gap in the clouds, worst case.

[georgegassaway]

A generic forecast by a site like Weather.com, that it is likely to rain each day for a week, does not mean weather is not likely to be able to allow launch unless some very sensitive rocket can’t launch if there has been ANY rain or lightning in the preceding 24 hours.

What is far more relevant are the 45TH Weather Squadron’s forecasts. They are considering all of the issues, as regards the likely weather at that specific time for the day of launch.   A Thunderstorm  in the area 30 minutes after launch, does not affect the launch (post-landing crew at LZ-1 not so happy).  Rain 3 hours before which stops 2 hours before and the skies clear enough, no problem for launch AFAIK.

IIRC, there were rarely shuttle launches delayed by weather (and of course one that SHOULD have been).  People are talking now like weather at the Cape in summer is a huge problem that interferes with launch attempts on a regular basis.

They’ve got a 70% chance of launch for Saturday. Much like Thursday. And they were close to being able to launch Thursday as it is, had T-0 been set for bit earlier (or perhaps 2 or more hours later).

Statistically, 30% chance of not flying means just 10% chance of not flying (thus 90% GO) over a period of three different days with the same odds.        

(Yes, I know, would still be 30% chance of No-Go on any specific day… )

[Raul]

SpaceX looks like it is continuing its testing of extended loiter time for upper stages.  Compare 2nd stage disposal areas of previous CRS missions vs. CRS-11 (from Raul's maps).  Looks like it is being done at least 1 orbit later.

That is 15 orbits later, not just 1. The orbit passing over Florida reaches its southernmost point around the longitude of New Zealand. The orbit after that is shifted ~1000 miles west and reaches its southernmost latitude near Tasmania.

The hazard area shows an orbit with it's southernmost point ~1000 miles EAST of New Zealand. That's the orbit BEFORE passing over Florida... or 15 orbits (22.5 hours) later.

No, S2 reentry is during first orbit, because this hazard area is active only until T+80minutes after liftoff.
Problem was, that issued CRS-11 S2 Debris Area as HYDROPAC 1853/2017 was wrong (as it was in case of CRS-10 too). In this case was mistaken west longitude instead east longitude.

Newly issued HYDROPAC 1934/2017 with correction - updated in the map.

[IanThePineapple]

https://twitter.com/nova_road/status/870831117066174464

This isn't looking too good, still awaiting official or reliable confirmation.

[ZachS09]

https://twitter.com/nova_road/status/870831117066174464

This isn't looking too good, still awaiting official or reliable confirmation.

If tomorrow's attempt is scrubbed, that means that some of the cargo might be changed out again. That's if it's another 48-hour turnaround.

[ChrisGebhardt]

https://twitter.com/nova_road/status/870831117066174464

This isn't looking too good, still awaiting official or reliable confirmation.

If tomorrow's attempt is scrubbed, that means that some of the cargo might be changed out again. That's if it's another 48-hour turnaround.

Not necessarily true.  While NASA has stated that SpaceX is working on what the turnaround plan would be if we scrub today, there was no mention of cargo change-outs automatically kicking in for a 48hr turnaround.  Doesn't mean there might not be, just keeping things clear.

[Jim]

With the 48 hr scrub turnaround, couldn't Spacex have done a one day rendevous trajectory?

[Norm38]

How much more fuel does that take?  They don't have the barge ready, and the scrub wasn't their fault.

[Jim]

It had nothing to do with who called the scrub.  The two day rendezvous allows for daily launches.  If there isn't going to be daily launch attempts, then why not go for first day rendezvous

[butters]

With a long-range forecast like this for the ISS afternoon launch windows from the Cape, it begs the question: can BulgariaSat launch at night and jump in line?