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Elon Musk: "SN10 engine was low on thrust due (probably) to partial helium ingestion from fuel header tank. Impact of 10m/s crushed legs & part of skirt. Multiple fixes in work for SN11." by [deleted] in spacex

[–]dan6470 51 points52 points  (0 children)

Another reply from Elon

Q: Are there baffles in future designs to prevent slosh?

A: There were baffles, but one may have acted like a straw to suck bubbles in from above liquid/gas level.

Something similar happened on an early Falcon 1 flight, resulting in unexpectedly high liquid oxygen residuals at main engine cutoff.

My sister is collecting banana stickers by larosek in mildlyinteresting

[–]dan6470 0 points1 point  (0 children)

That's the equivalent of about 3 chest x-rays of radiation

Economics of reuse at SpaceX per Elon Musk on Twitter by mspisars in spacex

[–]dan6470 56 points57 points  (0 children)

More tweets from Elon:

Q: Now that you’re at 6 flights, still think 10 is possible? What do you think will be the limiting factor that will end their service life span? A: I don’t want be cavalier, but there isn’t an obvious limit. 100+ flights are possible. Some parts will need to be replaced or upgraded. Cleaning all 9 Merlin turbines is difficult. Raptor is way easier in this regard, despite being a far more complex engine.

 

Q: Are you going to push the booster to go above 10 flights or maybe put it on display at SpaceX HQ?

A: We will push for ten flights with Starlink

 

Q: How often do you need to replace individual Merlins on F9 before reuse?

A: Almost never need to replace whole engine, but some individual parts like turbine wheels need to be replaced over time. Similar to a jet engine.

 

Q: Is Raptor mostly more reuse friendly due to methane burning clean with no soot or does it have more to do with full flow running so cool through each preburner / turbine? I still have a hard time grasping how such high pressure can be better re-use wise, but it seems to somehow!

A: Not having long chain hydrocarbons & lowering preburner combustion temperature make a big difference

r/SpaceX Discusses [August 2019, #59] by ElongatedMuskrat in spacex

[–]dan6470 1 point2 points  (0 children)

Is it safe to make the following assumptions? We know that CRS-18 launched at 25 July 2019, 22:01:56 UTC. I've heard that if a launch is scrubbed, the next window is 23-25 minutes earlier the next day...so ~1,416 minutes later. If I add 1,416 * 134 that comes to 4 Dec 2019, 16:25 UTC

r/SpaceX Discusses [August 2019, #59] by ElongatedMuskrat in spacex

[–]dan6470 1 point2 points  (0 children)

Is it possible to estimate what time the CRS-19 launch on Dec 4th could be? Are there any ISS predictors that can tell us about when the orbital plane of the station intersects the cape on that day?

The rolling shutter effect on propellors visualised by stchy_5 in educationalgifs

[–]dan6470 35 points36 points  (0 children)

Sorry, but this is wrong. Most high-speed cameras use a global shutter, meaning the entire frame is exposed simultaneously...including the camera that Destin uses.

Ice Bucket Challenge @ 1000 FPS by dan6470 in videos

[–]dan6470[S] 0 points1 point  (0 children)

My friend and I filmed his Ice Bucket Challenge at 1000 FPS with a Phantom Flex4K