Author Topic: SpaceX Falcon 9 : Iridium NEXT Flight 2 (June 25, 2017) : Discussion  (Read 111784 times)

Offline kevin-rf

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They would still have to build 2 second stages a week.
« Last Edit: 06/30/2017 12:33 PM by kevin-rf »
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Offline Robotbeat

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With 2 pads shooting and the potential for several launches a week, ISTM they're going to need either more ASDS's or a much faster platform equipped ship/catamaran/?..? - or two.

Or RTLS. Block 5 may allow RTLS for Iridium NEXT launches. (speculation)
Theyre not going to sustain over a hundred launches per year before ITS or similar.

Why not? 100 launches approx two per week. They will have three launch pads (plus Boca Chica to make 4). That's just over a week per pad per launch. They are not far of that now. They'll probably need another drone ship though.
Because I don't think it'll take that long to build a smaller ITS. And they very well may prefer that to building another droneship & other upgrades needed to get to over 100 flights per year.

And Boca Chica may never have kerosene infrastructure installed.
« Last Edit: 06/30/2017 12:47 PM by Robotbeat »
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Offline LouScheffer

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It's neat that the hand-written "s/n 003" is still visible on the left grid fin, as well as the tiny core number "36" just below the central grid fin. (Image from the update thread)
Hope they wrote it with the right marker.   There's a story from the SR-71 that the ink from Pentel markers caused the titanium to fail.
Quote
Although titanium is thought to be an indestructible material, it was found that this metal exhibits extreme sensitivity to contaminants such as chlorine, fluorine, and cadmium. For example, during fabrication, it was discovered that the chlorine based ink of a Pentel marker used to layout the titanium sheets caused them to fail after exposure to heat.

Online JamesH65

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With 2 pads shooting and the potential for several launches a week, ISTM they're going to need either more ASDS's or a much faster platform equipped ship/catamaran/?..? - or two.

Or RTLS. Block 5 may allow RTLS for Iridium NEXT launches. (speculation)
Theyre not going to sustain over a hundred launches per year before ITS or similar.

Why not? 100 launches approx two per week. They will have three launch pads (plus Boca Chica to make 4). That's just over a week per pad per launch. They are not far of that now. They'll probably need another drone ship though.
Because I don't think it'll take that long to build a smaller ITS. And they very well may prefer that to building another droneship & other upgrades needed to get to over 100 flights per year.

And Boca Chica may never have kerosene infrastructure installed.

A smaller ITS or ITS itself are both quite a few years away. If they decide to even make a smaller ITS* which I regard as unlikely. Drone ship is a few months to construct.

As stated above, the second stage is the bottleneck.

They already have a working launcher, which is going to be in use for at least a decade I would think. They just need the improvement to infrastructure to get up to the 100/year rate.


*I don''t like the phrase mini-ITS, because that's exactly what it isn't. It's not an interplanetary transport system, mini or not. A subscale prototype, if they go that way.

Offline rpapo

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It's neat that the hand-written "s/n 003" is still visible on the left grid fin, as well as the tiny core number "36" just below the central grid fin. (Image from the update thread)
Hope they wrote it with the right marker.   There's a story from the SR-71 that the ink from Pentel markers caused the titanium to fail.
Quote
Although titanium is thought to be an indestructible material, it was found that this metal exhibits extreme sensitivity to contaminants such as chlorine, fluorine, and cadmium. For example, during fabrication, it was discovered that the chlorine based ink of a Pentel marker used to layout the titanium sheets caused them to fail after exposure to heat.
You guys do recall the story about the SR-71, right?  About how they puzzled over why the titanium parts made in the summer failed more often than the ones made in the winter?  In the summer, there was more chlorine in the air around Burbank because of swimming pools.
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Online Lars-J

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Here is a good before/after comparison of the grid fins and surrounding area.  :)   (both shots from the SpaceX Flickr account)
« Last Edit: 06/30/2017 05:02 PM by Lars-J »

Offline SLC

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It's neat that the hand-written "s/n 003" is still visible on the left grid fin, as well as the tiny core number "36" just below the central grid fin. (Image from the update thread)
Hope they wrote it with the right marker.   There's a story from the SR-71 that the ink from Pentel markers caused the titanium to fail.
Quote
Although titanium is thought to be an indestructible material, it was found that this metal exhibits extreme sensitivity to contaminants such as chlorine, fluorine, and cadmium. For example, during fabrication, it was discovered that the chlorine based ink of a Pentel marker used to layout the titanium sheets caused them to fail after exposure to heat.
You guys do recall the story about the SR-71, right?  About how they puzzled over why the titanium parts made in the summer failed more often than the ones made in the winter?  In the summer, there was more chlorine in the air around Burbank because of swimming pools.
Won't the grid-fins get a lot of salty wind and sea-spray on their barge-journey?  Will all those chloride ions cause any problems?

Offline daveglo

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To expand on the titanium corrosion questions, titanium is only susceptible to chloride-induced corrosion cracking in a high-temperature environment.  And titanium develops an oxide film almost immediately in the presence of oxygen, so as long as there are no chlorides present at manufacture, the grid fins should not be exposed to chlorine during their high temperature operations.

By the time they're close enough to the surface to encounter salt air, the temperatures should be low enough to avoid the corrosive regime.  And any scoured oxide film will quickly re-establish itself once the airspeed drops during landing.

Lastly, I'll bet they get a good NDE upon return to land, before being re-certified for a future flight.

Offline LouScheffer

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It's neat that the hand-written "s/n 003" is still visible on the left grid fin, as well as the tiny core number "36" just below the central grid fin. (Image from the update thread)
Hope they wrote it with the right marker.   There's a story from the SR-71 that the ink from Pentel markers caused the titanium to fail.
Quote
Although titanium is thought to be an indestructible material, it was found that this metal exhibits extreme sensitivity to contaminants such as chlorine, fluorine, and cadmium. For example, during fabrication, it was discovered that the chlorine based ink of a Pentel marker used to layout the titanium sheets caused them to fail after exposure to heat.
You guys do recall the story about the SR-71, right?  About how they puzzled over why the titanium parts made in the summer failed more often than the ones made in the winter?  In the summer, there was more chlorine in the air around Burbank because of swimming pools.
Won't the grid-fins get a lot of salty wind and sea-spray on their barge-journey?  Will all those chloride ions cause any problems?
I am not a metallurgist, but the erosion rate of titanium , Table 3, "Resistance of Unalloyed Titanium To Corrosion by Aerated Chloride Solutions":, erosion when exposed to sodium chloride near room temperature is stated as "nil", or less then 0.01 mm/year.  Should not be a problem...

Offline Lar

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Chloride ions are far less reactive than chlorine. Sea spray contains chloride ions, not chlorine (well, it might contain a bit of chlorine from drained pools or discharged land waters of various sorts, but a LOT less...)
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Offline Kabloona

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You guys do recall the story about the SR-71, right?  About how they puzzled over why the titanium parts made in the summer failed more often than the ones made in the winter?  In the summer, there was more chlorine in the air around Burbank because of swimming pools.

Generally correct, but the chlorine wasn't wafting through the air from swimming pools, it was in the tap water they were using to wash the titanium parts. When they discovered this, they switched to distilled water for washing titanium, and the problem went away.

https://tinyurl.com/y9ao4x9v
("SR-71" by Paul F. Crickmore)

Coincidentally, the above book excerpt also mentions the problem caused by writing with
Pentel pens on titanium sheet that LouScheffer mentioned upthread.

(Credit to acsawdey for finding the above book excerpt and posting it in the continuing saga of titanium grid fin S/N 003 that flew again on the FH demo mission.
https://forum.nasaspaceflight.com/index.php?topic=44778.msg1792723#msg1792723)
« Last Edit: 02/24/2018 02:07 PM by Kabloona »

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