Racescort666

MUSIC!

!!! Still out of likes. Is this a 24 hour curse or what?

The nozzle is, the combustion chamber is channel wall construction. They did this to save cost over tube wall construction like RS-25 and RL10.

I'm out of likes but this is most hydrolox engines. I won't say all hydrolox engines but the ones I know the stats for all run considerably hydrogen rich. RS-25, RS-68: O:F 6:1, RL10: 5.5:1, these are both by mass but not as high as I thought they were. Brain fart. As for the trade offs of running hydrogen rich, running closer to stoichiometric increases the temperature of the exhaust gasses which increases specific impulse but decreasing the the molar mass of the exhaust gas also increases the specific impulse. In other words, there is a balance between fuel rich and maximum energy input that gets you the peak efficiency. So, for the RS-25, RL10, and the RS-68, they all run way more fuel than oxidizers. It's also worth noting that the RS-25 and the RL10 are regeneratively cooled while the RS-68 is ablatively cooled so the ablative material is in the exhaust as well which slightly decreases the specific impulse.

@magnemoe, thanks for pointing me toward degenerated matter. I guess I was assuming that such a concept existed but ultimately unfamiliar with it... until now. So, now that I've spent the better part of my evening reading wikipedia articles on things that were totally glossed over in my physics classes, I have more questions. But first, I'm going to cover a bit of what I read to make sure I understand it (people that understand physics better than I do, please correct me where I am wrong): Degenerate Matter (from the White Dwarf Wikipedia page): Is this type of state isn't limited to white dwarf stars? This much makes sense: degenerate matter in white dwarf stars is caused by gravity where there is sufficient gravity to collapse what's left of the star into super-dense matter after the thermal pressure of fusion has ceased. The only thing keeping it from collapsing into a black hole is the degeneracy pressure. Basically: gravity > how-far-atoms-want-to-stay-away-from-each-other-normally. So, does this condition exist in the cores of typical planets? Or specifically, gas planets? As the outer layers of a gas planet are blown off wouldn't this condition no longer be present? Hypothetically, it takes thousands/millions of years for the gas part of a gas planet to be blown away right? Wouldn't there be a gradual transition on the core and the extreme pressure relieved? Super crazy theory: the metals at the surface (or mantle... I guess... this is definitely not my area of expertise) of the core are strong enough to maintain the pressure to support the degenerate matter under the surface because they've formed some phase/alloy of metal that we've never imagined. Am I asking questions that don't have answers? Existential crisis incoming in 5... 4... 3... 2... 1... Ninja'd on my own question. Is the density determined by the equilibrium between the electron degeneracy pressure and gravity then? ETA: @ProtoJeb21, I wish I could like your last post more than once because in the last 2-3 hours I spent reading wiki articles, I was wondering exactly that. It's so great to learn new things.

Please excuse my ignorance on this but how do planets achieve such high densities? Is it like how neutron stars are basically star sized atomic neuclei? If the surface has iron and tungsten on it wouldn't the density of the surface materials be 7.8 g/cc and 19.2 g/cc respectively but that is less than the densities discussed? Am I thinking about it wrong because these are their densities at STP and they have different densities and/or assume different forms at absurd pressures like those found at the core of a gas giant? How do they keep those densities and forms with the lighter gas blown away?

I would hazard a guess that FH launch will be at the very end of November if it doesn't get pushed into December. Although from a timing standpoint, OTV-5 is the last launch from LC-39A according to Spaceflight Now and if it launches on schedule (reasonably, it might not), 60 days after that (the amount of time that SpaceX has said they need) is November 6th. So I think that delays to Falcon Heavy would probably be more related to Falcon Heavy itself rather than other SpaceX flights or the pad modifications, assuming that November 30th is the latest non-delayed date.

I wasn't able to find much information on how the aerodynamics of the orbiter are used during ascent but during descent, they don't even use the rudder until they've slowed to approximately mach 1: https://www.nasa.gov/audience/forstudents/9-12/features/F_Aeronautics_of_Space_Shuttle.html I couldn't find the original document that said what controls they used at what part of the flight envelope but yaw control is the last one they switch to aerodynamic control. The first part of entry is at something like mach 25 but they're going too fast and the atmosphere is too thin for the aerodynamics to work so they use RCS. Although the body flap I think controls the AOA. It's also worth noting that the orbiter is almost entirely flown by computer even though the RCS/control surfaces are tied right into the stick. ETA: (of course as soon as I post, I think of something else) It's entirely possible that with the fly-by-wire, they compensate for roll while using the rudder with the elevons automatically. This is something that KSP is not very good at.

The stream quality was pretty terrible but pretty cool to see that thing go. I'd love to see a proper video of the launch, looks like they'll have some pretty good angles.

Also, I came across this PDF linked on reddit: https://www.nasa.gov/sites/default/files/atoms/files/ccp_nac_july24_2017.pdf It discusses the technical readiness of SpaceX and Boeing for commercial crew operations.

It's also worth noting that the last launch on LC-39A is listed as OTV-5 on September 7th according to SpaceFlight Now and the rest of the F9 flights don't have a pad listed for the east coast launches.

Effectively yes, they still require capital from investors and haven't stabilized into a profitable company. The valuation is just an estimate of future value of the company (it's more nuanced than that but it's the basic idea). They're probably more profitable than Tesla which still has a net loss and also a ridiculously high valuation. To me, the biggest difference between Tesla and SpaceX is that the launch market isn't saturated while automotive is definitely saturated and mature. The auto companies are very streamlined in their process, development, procurement, etc. to reduce their costs.

STP-2 is now NET April 30th. I have a buddy with a payload on that flight so I'm pretty excited. I'm also excited for the FH demo which is still supposed to be this year. I wonder what they are going to do with it?

Yes, teargas is banned for use in warfare: https://www.opcw.org/about-chemical-weapons/types-of-chemical-agent/riot-control-agents/ The US us a signatory member of the Organization for the Prohibition of Chemical Weapons as are about 98% of other countries. How it applies to the police is discussed further by Politifact: http://www.politifact.com/truth-o-meter/statements/2014/aug/26/facebook-posts/tear-gas-was-banned-warfare-1993-police-1997/ I was wrong on the Geneva Protocol which the US Military felt didn't apply to riot control agents (see section US Field Manual): https://ihl-databases.icrc.org/customary-ihl/eng/docs/v2_rul_rule75 However the Red Cross seems to think that the Geneva Protocol does apply to RCAs. The prohibition on teargas is specific to warfare and not training. I don't have first hand experience with teargas but I'll take your word for it, it sounds pretty nasty. Back on topic: LaWS is pretty awesome. Is it intended to replace and/or compliment CIWS?

I still prefer fuel injection.

Which makes teargas an interesting choice for police departments considering it would be a form of chemical weapon, banned under the Geneva Protocol, but common practice to use on civilians. /offtopic

https://spaceflight.nasa.gov/outreach/SignificantIncidents/assets/eva_incidents2016.pdf Holy crap. Note to self: don't get out of a spacecraft.

For the launch abort test, it's possible that they ran the test on a partial test and ballasted the vehicle to be the appropriate weight. In fact, they almost certainly needed ballast to get the vehicle to the flight weight. We don't know if they burned a full tank of fuel for the test whether it was partially filled, smaller than production intent, or shut down early. The dV estimate for the LES is basically a minimum value without a solid maximum. Also, I wouldn't be surprised to see them attempt a propulsive landing on a cargo mission although that would probably require NASA approval since SpaceX returns science cargo that presumably has to survive the landing.

Exactly, he's like "well if it clears the pad without damaging it, I'll consider that a win." Strangely pessimistic given other things he's said.

I don't know if this should be broken into its own thread but would you need a space suit on Titan? Aren't space suits more to provide pressure for our body (and protection from radiation and stuff) but would it be necessary on Titan since it has a dense atmosphere? Obviously you'd need some sort of protective equipment since it's -180 C and there's no oxygen to breathe but you presumably wouldn't need a full blown EVA suit.

Balloon launched doesn't actually sound that crazy when you start thinking about it.

I thought stuff got unloaded once it got out of 2.5 km physics range. Any idea what mod they're using?

It keeps reverting to VAB though...

Abort again?!

Me too. I almost didn't make it because I was at work changing the tires on my car. Now I'm at my desk watching on my laptop.