Quote from: wannamoonbase on 06/06/2016 12:41 pmQuote from: Rebel44 on 06/06/2016 07:11 amNow that Falcon 9 design is "frozen", is SpaceX going to prepare further improvements and add them all at the same time (F9 v1.3?), when they reduce their backlog of flights?Are modifications to improve recovery also part of this design freeze, or only main rocket parts?Disciplined configuration control? Would be nice but they have not shown a history of doing so.Constant iteration of a design does not exclude disciplined configuration control. Unless you have insight into SpaceX's internal change management and design drawing release systems and how they integrate into their systems engineering and mission planning, you're talking out of your derrière.
Quote from: Rebel44 on 06/06/2016 07:11 amNow that Falcon 9 design is "frozen", is SpaceX going to prepare further improvements and add them all at the same time (F9 v1.3?), when they reduce their backlog of flights?Are modifications to improve recovery also part of this design freeze, or only main rocket parts?Disciplined configuration control? Would be nice but they have not shown a history of doing so.
Now that Falcon 9 design is "frozen", is SpaceX going to prepare further improvements and add them all at the same time (F9 v1.3?), when they reduce their backlog of flights?Are modifications to improve recovery also part of this design freeze, or only main rocket parts?
Quote from: Herb Schaltegger on 06/06/2016 02:44 pmQuote from: wannamoonbase on 06/06/2016 12:41 pmQuote from: Rebel44 on 06/06/2016 07:11 amNow that Falcon 9 design is "frozen", is SpaceX going to prepare further improvements and add them all at the same time (F9 v1.3?), when they reduce their backlog of flights?Are modifications to improve recovery also part of this design freeze, or only main rocket parts?Disciplined configuration control? Would be nice but they have not shown a history of doing so.Constant iteration of a design does not exclude disciplined configuration control. Unless you have insight into SpaceX's internal change management and design drawing release systems and how they integrate into their systems engineering and mission planning, you're talking out of your derrière. Fair enough. Configuration control wasn't the right term to use, Stabilized design would be better. I'm all for improvements, rolling them out continuously instead of doing releases is messy not just for production and manufacturing. But I can imagine that insurers have a general level of unease with SpaceX. It's a young company doing new things, but they are creating problems for themselves if they keep up the same behavior. Implementing reuse with a series of vehicles, each one potentially different than the others will be cost and schedule management nightmare.
I'm all for improvements, rolling them out continuously instead of doing releases is messy not just for production and manufacturing. But I can imagine that insurers have a general level of unease with SpaceX.
The trick with continuous revision is managing what configuration each unit is currently, and managing what units get backported from their as built (or as last modified) to the desired current config. Some change items may not get applied and some may.Interesting problem. But not unsolvable.
Quote from: wannamoonbase on 06/06/2016 03:40 pmI'm all for improvements, rolling them out continuously instead of doing releases is messy not just for production and manufacturing. But I can imagine that insurers have a general level of unease with SpaceX.Please no FUD. Not a page ago in this thread, there was a link to article where an insurer stated that he was fine with it and that SpaceX had credibility to do these things.
Upgrades underway to enable rocket to compensate for a thrust shortfall on one of the three landing engines. Probably get there end of year.
https://twitter.com/elonmusk/status/743099301174247424Quote from: Elon MuskUpgrades underway to enable rocket to compensate for a thrust shortfall on one of the three landing engines. Probably get there end of year.Would a full, Dragon-2-esque bank of pressure fed SuperDracos be up to the task?
I'm thinking that fuel lines are being occasionally damaged on hot reentries, leading to both the loss of prop and thrust at landing and the residual fires.
Quote from: abaddon on 06/15/2016 04:09 pmQuote from: Chris Bergin on 06/15/2016 03:15 pmNext one is LZ-1 (unless Elon wants another go at a CRS-to-ASDS).IIRC, with CRS-8 Elon said that the droneship landing had a better chance of success due to margin being a little low for an RTLS. Also, from a PR perspective, it's probably better to do a droneship landing than have a RUD like the one today at LZ-1. Will be interesting to see which way they go.But a landing would mean they have more time to do an inspection of the droneship. Also, a landing is a lot better recovery option, significantly cheaper.
Quote from: Chris Bergin on 06/15/2016 03:15 pmNext one is LZ-1 (unless Elon wants another go at a CRS-to-ASDS).IIRC, with CRS-8 Elon said that the droneship landing had a better chance of success due to margin being a little low for an RTLS. Also, from a PR perspective, it's probably better to do a droneship landing than have a RUD like the one today at LZ-1. Will be interesting to see which way they go.
Next one is LZ-1 (unless Elon wants another go at a CRS-to-ASDS).
Quote from: Lar on 06/06/2016 04:05 pmThe trick with continuous revision is managing what configuration each unit is currently, and managing what units get backported from their as built (or as last modified) to the desired current config. Some change items may not get applied and some may.Interesting problem. But not unsolvable.Exactly, and the rocket business is pretty good place for this. Implement drawing change, replace drawings on floor for the next serial number. File away travelers and red lines from build on that unit, and log drawing revision used to build it in the database. Rinse, repeat. Continually. No need for it to be messy or confusing as long as you're disciplined about it (aka, not backporting unless mission critical, having good floor practices, etc).
Quote from: envy887 on 06/15/2016 04:27 pmI'm thinking that fuel lines are being occasionally damaged on hot reentries, leading to both the loss of prop and thrust at landing and the residual fires.If it were a fuel line problem causing loss of landing thrust, they'd know that from telemetry and be making the appropriate fix. But according to Musk's tweet today, he says they'll be "upgrading" the vehicle to "compensate" for low-thrust anomalies at landing. Which makes it sound like the low-thrust problem may be an unavoidable result of landing with too-low propellant levels, possibly helium bubble ingestion caused by propellant slosh, etc.If it were simply a matter of heat-damaged fuel lines, they'd be fixing that with more insulation, etc, rather than figuring out how to live with the problem. And it wouldn't be taking them 6 months to implement.Musk's tweet:QuoteUpgrades underway to enable rocket to compensate for a thrust shortfall on one of the three landing engines. Probably get there end of year.So the only real "fix" may be having enough propellant margin to prevent helium bubbles from getting into the fuel line in the first place, and for high-performance missions where that's not possible, these "upgrades" that somehow may make a low-thrust anomaly less fatal.