/sci/ - Science & Math

I hope spaceXXX doesn't run out of money, current development is too spicy. no one stops

Cygnus capture is coming up soon

https://twitter.com/Space_Station/status/1119157055724478465

https://www.youtube.com/watch?v=21X5lGlDOfg

RIP Core-chan.
Her thrust will never be nominal again.

>>10571583
Did it flip because rough seas or what?

>>10572269
that's the story as we've heard it

>>10571583
F

>>10571535
Soviet apace best space! Did you know that the soviets experimented with welding welding in space during the soyuz 6 mission? During the test they melted through the test plate and some of the hull with a fucking electron beam.
https://awo.aws.org/2015/07/welding-in-space/
Since we're gonna have big fucking rockets soon, we should bring back all those space construction concepts that got investigated before being thrown in the trash. The biggest space construction we have, the ISS, is made of fucking duplo blocks. Back when people still had dreams, they were talking about making huge truss structures.

>>10572337
The problem with making big things in space is the funding and political motivation.

If it's not for scientific reasons nor funding a pork-barrel, then it's not worth it for most space agencies. Hopefully this changes soon, I'm tired of hearing about big ideas from them and then seeing nothing of it years later.

lots of activity at Boca Chica.

https://www.youtube.com/watch?v=CbB2ZjUX3v4

>>10572388

>>10571578
When is this supposed to happen, exactly, because I've been running this stream for quite a while.

>>10572388
HOP ALREADY YOU DUMB SHINY SLUT, AAAAAAAAAAAAAAAAAAAAAAH

>>10572388
Well it looks like they're prepping for 2 engines hopper, which should be able to do hops, as it can into roll control.

>>10572595
I'm beginning to wonder if SpaceX is intentionally not showing much about Starhopper to build up hype via blue balls.

>>10572602
Nah, the bottleneck here is how fast they can make them Raptor engines.
see >>10572599
With 2 engines they can into serious flight control.

>>10572573
It happened hours ago m8, read the tweet.

>>10572482
>When you have the baby Starship whisper to it "Hi baby Starship" in a very soft voice.

>>10572981
new assembly structure concrete thing. Big boi

>>10572988

>>10572991

>>10572995
concrete slabs delivered, lots of dirt work at the launch pad.

>>10573000
Looks like they're working up a new launch pad to deal with punishment from multiple raptor firings.

>>10572981
>largest interplanetary vehicle construction facility

>>10573002
yeah. The mystery is the gigantic new concrete jig thingy. Assembly facility?
some videos are up on the @SpaceXBocaChica FB page

>>10573010
My bet is on foundations for a water tower.

>>10573024
they do need a water tower, don't they?

>>10572348
Big structures need not be massive. They just need to be stiff enough that their resonant frequency is above the operating frequency. In the context of space systems operating frequency is basically how fast we want to point at shit. You can actually put up a pretty damn big structure with shuttle level cargo capacity if it's all in pieces.
>>scientific
kilometer wide telescopes. There's also value in putting up a small(300x300m) solar power satellite to demonstrate the tech to build a bigger one. A demonstrator would fit in 1.5 starship launches. We're pretty close to getting the robotics necessary to do this
>>pork barrel
funny you mention that. NASA Langley was able to do a bunch of space construction research because hey it will give the SLS something to do.

>>10572981
We need some goddamn drone footage

Hey /sfg/, I wrote a rudimentary code to simulate a single stage rocket flying upwards.

One of the variables that can be altered is the exit pressure of the exhaust of the engine. What the code is telling me is that the rocket will have the highest apogee if it had an exit pressure such that the rocket had no nozzle. Expanding the flow past the throat (i.e. having a nozzle) will result in the rocket having a smaller apogee.

>With a nozzle so that the exit pressure is 1 atmosphere = 7.5 km
>With no nozzle = 17.5 km!

This makes so sense to me, but maybe someone can make sense of this.

>>10573189
Nevermind. Just found the problem.

The exhaust exit velocity wasn't coupled to the exit pressure.

My bad. I'm an idoit.

What do ya'll think of Moon Direct?
https://spacenews.com/op-ed-lunar-gateway-or-moon-direct/
At first I was like damn Zubrin, you're crazy mining lunar water which may or may not exist in permanently shadowed craters using microwaves beamed from ~100 km, then carrying out a manned offworld overland expedition to move tonnages of it over that same distance to eventually be electrolyzed and stored cryogenically on the lunar surface.
But then Zubrin said
>>the round-trip propulsion requirement to travel between the Gateway and the lunar surface (a delta-V of 6 km/s) is identical to that needed to fly one-way from the lunar surface to low Earth orbit
So like I'm all for moon direct now. Why the fuck are we even doing the gateway? (besides pork)

>>10573197
it's a lot harder for a politician to say "don't use the lunar gateway" than it is for them to say "quit going to the moon"

>>10573197
>>10573199
I'm almost inclined to believe that American politics has ruined American spaceflight.

>>10573208
it's almost like politics ruins everything it touches?
sooner or later manned commercial spaceflight is going to become a reality and then shit'll really kick off

>>10573197
That's technically BFR with more steps.

>>10573024

>>10573197
It really depends on what the goal is. If the goal is to build infrastructure to allow repeated access to the moon, a Lunar Gateway makes sense, but even for a one-off trip, you'd still need a "lunar gateway," only it'd be temporary. In a way it feels like the best way to get back to the moon by 2024 is to use Falcon Heavy to put a launch station in LEO with a vehicle that can go to Lunar orbit and back and a Lunar lander in Lunar orbit, and use Crew Dragon to get from Earth to LEO and back. We're pretty good at rendezvous these days, and it would only waive the need to rely on unproven rocketry. We know how space stations work, so we'd only need to develop a shuttle and lander, both of which can be developed quickly (since we've done them before with the Saturn V third stage and lunar module) and tested with Falcon Heavy without humans. Theoretically being cheaper to launch with a bigger rocket doesn't mean shit if said bigger rocket doesn't fly and costs billions of dollars. Right now the SLS is going to cost two billion US dollars per launch. You could put the LEO station and vehicle, the Lunar station and lander, the trans-lunar test vehicle, and lunar lander test vehicle up with Falcon Heavy for 1/4th the price. Then the only launch cost of a lunar mission is two Falcon 9 launches, one with fuel and one with crew and short term supplies. As needed, additional Falcon Heavy (or other heavy launch vehicles as they become available) launches can put heavy equipment on the moon, eventually allowing fuel production, at which point it starts to make sense to keep spacecraft in lunar orbit.
So the first step should be a tranlunar vehicle and lander that park with a station in LEO when not in use, so they can keep fueled easier in case we can't go to the moon for a few years. Once we have a fiel producing automated lunar base, it might make sense for a lunar station to hold a lander, and fuel the TLI vehicle when it goes there.

>/sfg/
/sg/ or /sfg/, please pick one, just stop fuckin alternating between the two. all the other threads have been using /sg/

>Gateway is useless and the Dv difference between docking with Gateway vs. landing on the moon directly is too much!

Well what do you have to say about it now fags, the d/v difference is negligible

Update:
>April 19: Falcon 9/SpaceX CRS 17 delayed from April 26th
New date looks to be set for April 30th.

>>10573661
The problem isn't that LOP-G takes up too much DeltaV to get there, it's been known that it's orbit is slightly easier to get to than directly to the Moon.

The problem is that the LOP-G orbit enables operations at LOP-G and not much else. If you want to go from LEO to NRHO to the Moon, then you are expending more DeltaV than if you just went straight for the Moon.

LOP-G really doesn't have a purpose other than being ISS 2.0.

>>10573671
>more delta-v

like the graphic shows, its a negligible difference did you even open the image it refutes you outright

>>10573676
Not him. The main problems with it are cost and usefulness. We still don't know how to live in space for long periods of time. Operating a lunar station would be very expensive. How long would humans be there at a time? What happens if we can't send more humans for a few years? Will it have artificial gravity? Fuel, food, and water would have to be sent there regularly from Earth. And for what purpose? Slightly faster communication times?

>>10573676
Sorry, misread the image.

I guess you have a point in that the DeltaV difference isn't that great (if the graphic is to be believed that is). I personally still don't like the LOP-G due to the political mess that's tied to it.

Do you have a source for this graphic? In particular how these DeltaV's were calculated.

>>10573693
Found it here https://www.nasaspaceflight.com/2019/04/nasa-lsp-studies-alternate-orion-options/,, they do explain it as such

>We based our analysis on the change in velocity (typically referred to as delta-V) required to get from low Earth orbit (185 km altitude circular parking orbit is what we primarily used in the study) into lunar transfer orbit,” they said. “That delta-V value is approximately 3.1 km/sec when departing from the 185 km circular parking orbit. In fact, for any low circular parking orbit near this altitude, the TLI delta-V will be approximately 3.1 km/sec.”

>>10573700
Thank you.

>>10573661
you can't add dV like that tho

So I was a little bit too ambitious when I wanted to make a rocket that could reach the Karman line. The best my design can do is 7.8km according to my "Poor man's RK4" MATLAB code.

At least the FAA doesn't have to worry about my rocket hitting commercial jets.

>>10573725
That's only true for parts of a rocket. You *can* add dV for destinations - otherwise dV maps wouldn't work.

>>10573661
Directfags BTFO

>>10574028
Do you even lift, bro
(+_+)

>>10573661

I <3 Gateway!

>>10573671
Oh the additional 1km/s has plenty of implications on lander design, especially ssto ones...

>>10571535
>Space Flight

damn you OP, spaceflight is one word, and I was wondering where the damn general was for past two days..

>>10573197
NASA knows better than some random lobbyist caring only about his corporate masters' financial interests.

>>10573197
Zubrin is not wrong but he is all about pushing is anti-Gateway BS as usual.

Gateway does not matter, what is important is using multiple commercial launches to achieve the missions. Now that is something that would decrease costs and accelerate development. Whether they stop at Gateway or not hardly matters either for delta-v or anything else.

>>10573208
It has. There's no almost about it. Hopefully the private sector can find more buyers for their services beyond military and NASA contracts.

what the fuck is going on at Elon Musk twitter. He's got an anime avatar lmao. I can't tell if it's still him and he's just gone off the deepend or if he hired someone to make waves

Chinese Linkspace tests their reusable rocket prototype again

https://twitter.com/AJ_FI/status/1119590816018780161

>>10574638
He does that regularly? What anime is that from?

Meanwhile at Boca Chica

>The concrete foundation of the new hangar building has been laid.

https://twitter.com/RogerLewisHolt/status/1119496084580110336?ref_src=twsrc%5Etfw

>>10574015
two rockets who both need 6 km/s is much easier than one rocket that needs 6.5 km/s, imo

>>10574643
Fullmetal Alchemist.

>>10574646
they don't know what that slab is for but okay

A few pics taken this morning of the various sections. -NSF

>>10574658

>>10574648
You're misunderstanding the point
You can just add delta v when you're figuring out how much it takes to get somewhere, but you can't when you're designing a rocket.

If your TLI burn takes 3.1 km/s and your capture burn takes 0.8 km/s, then you're gonna use 3.9 km/s, because it just adds.

>>10574658
>>10574662

Looks a lot smoother than the original ones, there's no hard angles between the sections of the cone.

Those welds look a bit shit though.

>>10572301
Full pic plz

I'm hyped for what Rocket Lab has to offer to be honest. I am proud of them and how far they have come from launching that sounding rocket Atēa-1

>>10574703
yeah, and two launch round trip LLO doesn't equal 13.1, it equals 9
meanwhile, two launch round trip NRHO doesn't equal 13.25, it equals 9.6
it doesn't matter how many rockets it takes you to get it up there, each leg of the journey only gets added in once

>>10574723

>>10574639
>Chinese Linkspace
>Chinkspace

Guess where this is...

>>10575014
better question is, what the fuck is it

>>10575059
A test stand for hold down firings

>>10574732
Also I just love the next mission patch too.

>>10575150
https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DL8cCPH1qnYI&ved=0ahUKEwih_dfbsN_hAhUrWN8KHcs9DVAQyCkITzAC&usg=AOvVaw3YBJxXYZ7PMQ4Rx_sy7iC7
>Let's forget [jeff] who

>>10574493
I know, but the previous thread had it as two words so I did the same. I'm not a regular baker.

>>10575318
Can I make a suggestion to keep it /sfg/? I think it makes more sense than /sg/.

>>10575150
https://www.youtube.com/watch?v=es4Yq7jP03w

>>10575325
Yea I did make that change, as /sg/ is a popular general on /pol/. Odds are I won't be the next baker though.

So, all the booster stages just landed successfully. A proper 3 for 3.

why doesn't spacex start a patreon or something

>>10575535
Just? The Arabsat-6A mission was nine days ago, my dude.

There has been an anomaly

https://twitter.com/EmreKelly/status/1119721013166657536

FUCK

I guess its better to find out the capsule blows up than try pad abort with those engines

>>10575646
Oh dear. Hopefully the capsule didn't get trashed.
When do you guys think that SpaceX will announce what happened?

Some guy on reddit is claiming his friend got interviewed at SpaceX's Florida Starship factory, apparently it's located at 850 Cidco Road, Cocoa, FL. Seems legit, considering this place is right next to a Coastal Steel Inc warehouse and the guy was able to describe in detail the welding test they made him do.

>The weld test they have you take is a flux core stainless on a 3/16" stainless butt-joint with a 1/8" open root in 2G, 3G and 4G. 2G and 4G may be different, but for sure he told me the 3G is welded from one side, then you flip it around, back-gouge it and run another bead on the backside and the material can not exceed 250 degrees.

>>10575661
I thought starship was going to be entirely metric?

>>10575646
I'm unclear, were they static firing the Draco thrusters on the DM2 or was this a fuckup with a F9 static fire with the DM2 on top?

>>10575678
Reports seem to be about the Dragon capsule for the upcoming crewed Dragon flight. No F9

>>10575678
Judging by the fact the cloud is the dark-brown/red color of leaked hypergolics I'd say its the former.

>>10575690
Yep

>>10574646
FFFFFFFFUUUUUUUUUCCCCCCCCCKKKKKK

>>10575678
>>10575688
It was the DM-1 capsule performing a SuperDraco hotfire at LZ-1, scheduled for the Abort Test in July.

>>10575014
This is a picture of the test stand at LZ-1.

>>10575710
If all the seats make it out of the launch pad from the explosion, does it pass the test?

>>10575703
Damn that looks like a big failure too.

Rip

Damn Elon making everyone work through the Easter weekend should have just tested next week

>>10575703
I live the smell of Hypergolics in the morning

Smells like... Lung cancer

Statement

>>10575714
It's really hard to gauge with hypergolics, could have just been an ignition failure with a big puff of MMH

>>10575740
>a big puff of MMH
*cancer cloud

>>10575731
>50m high cloud of cancer smoke
>Anomaly

Kek

>>10575731
Honestly knowing how busy the coast would be for the Easter holiday, probably better to not have tried anything this weekend.

>>10574639
>Welcome to Earth
I feel like I'm on aliexpress

commercial “delays” crew is such a shitshow timeline-wise

>>10575740
Its unreacted N2O4.

Multiple grapevines are indicating that it literally exploded into many pieces

Space travel will never happen. All the money spent before and now has been wasted when it could have been spent on the poor

>>10575859
>muh gibs
We should build rockets, if only to send all sub humans into the sun

>>10575859
> All the money spent before and now has been wasted when it could have been spent on the poor
No.
Just in the US...
>Sum of annual budgets of all major social programs: $556.6B
>Annual budget of NASA: $20.7B
So dumping all of NASAs budget into social programs would only increase money "being spent on the poor" by 3.72%. Considering how many poor people are still around today this means that hardly anything would change.

Meanwhile NASA has allowed for the development of spin off technologies such as: LASIK, aircraft anti-icing systems, water purification, etc. NASA also allowed for the development of orbital rocket technologies which opened up space services such as: weather tracking, global positioning, communions, crop monitoring, etc.

So no, money spent on NASA isn't a waste and directing it's budget on "the poor" would do more harm than good.

Go somewhere else.

"all but destroyed" according to Florida Today source

>>10575014
Mr L2 man what's the word on the DM-1 capsule? If they have pics from that vantage point was a camera rolling during the Draco & SuperDraco tests?

How feasible is a diy rocket with gaseous methane and oxygen as propellants? A regular 450 psi carbon fiber tank chilled to -100C can hold about 350kg of methane or oxygen, with a dry weight of less than 10kg. 3 of those, and a relatively simple engine, with a weight of less than 30kg, and some kind of structure to hold it together weighting 40kg, should be able to send a 50kg payload into low earth orbit (about 9400m/s deltaV at an ISP of 300).

At 10 bucks per kg oxygen, it would cost $7000 + some negligible amount for 350kg of methane to fuel the rocket. Maybe $500 for the 3 tanks, another $500 for the pipes, valves, and fittings, and then welding the structure from aluminum yourself.
That's less than $10,000 for a 50kg payload into LEO, or about $200/kg depending on how easy building the engine yourself would be. Since it is using gaseous propellants, there's basically no moving parts, so a simple combustion chamber with a nozzle welded together from 2 halves is all you need.

Anything obvious that I might be missing? How is it so cheap?

>>10575913
>A regular 450 psi carbon fiber tank with 12L volume
Fixed that part, else the numbers don't make any sense

>>10575906
holy fuck the boeing memers might've been right

this could put them far back enough that boeing beats spacex

>>10575881
I don’t think welfare fraud is a problem period I genuinely don’t. I don’t care when it happens and it means nothing to me. I’m glad. As if the government doesn’t steal from you every day lmao… I don’t give a damn

>>10575913
>How feasible is a diy rocket with gaseous methane and oxygen as propellants?
I assume that you mean a rocket that can reach LEO? Then that isn't very feasible, gaseous propellants while better performing than liquid propellants have such low densities that a reasonably sized rocket isn't going to be holding much fuel. Gaseous oxygen has a density of about 1.331 kg/m3 while liquid oxygen has 1141 kg/m3.

On top of that.
>and a relatively simple engine
Even a pressure fed, ablatively cooled engine isn't going to be simple. The injector alone is going to take alot of testing to get it right which drives up the cost.

>Anything obvious that I might be missing?
Other than what I have brought up? Lack of staging. There's a reason why there are no SSTOs.

Another thing is the dry mass you are estimating. According to your values, your rocket has a dry mass percentage of 20% (100*dry mass/total mass). That's really low for a low-tech rocket. Realistically you'll get 50% to 70%.

Not to discourage you. It's nice to see more people be interested in rocketry and would like to make their own rockets, but maybe you should lower your expectations. Maybe reach the Karman line (~2200 m/s DeltaV) or just 12km (~1200 m/s DeltaV)

Best of luck to you! I'm an aerospace engineer who's in a rocket design team and designing his own rocket too, so if you have more questions then don't be afraid to ask.

>>10574639
What a cute little hopper.

>>10575928
I wouldn't doubt it

>>10575928
Define "beat", is it really a win if the vehicle that flies first is essentially inferior in every way to it's competition?

>>10575937
What kind of rocket are you designing?
Thanks for you input, maybe I'm underestimating the weight of the engine, pipes, and structure around it? What problems could designing injectors for an engine with gaseous propellants compressed at more than 30 bar have? I would have expected it's literally just open a valve, point it into the combustion chamber and off you go.

>>10575946
Not that Anon but generally you want your injection system to feed a nice even flow of fuel and oxidizer into the combustion chamber to reduce or eliminate combustion instability and drag every drop of efficiency out of the engine. The two methods I've heard about are either a shower-head injection nozzle which basically has fuel and oxidizer pumped into two chambers stacked atop each-other which both dispense into the combustion chamber. It's heavier and less efficient but one of the most common methods, the other is counter-rotating swirl valves which are a single valve that is either machined or 3D printed into which separate fuel and oxidizer lines flow, the valve then sprays out fine cones of fuel and oxidizer which evenly mix together and ignite. This method is more efficient but relatively unused so far as I know.

>>10575946
>What kind of rocket are you designing?
A pressure fed rocket propelled by nitrous oxide and gasoline. My goal is just get as high as possible, and my estimates put it to 8km, but I am assuming some pretty pessimistic values.

>Thanks for you input, maybe I'm underestimating the weight of the engine, pipes, and structure around it?
Perhaps, what I do with estimating dry mass is to sum up all the dry mass that I know of and then multiply it by 1.35.

I also use this equation to estimate the mass of the engine...
m_engine = 0.725*F_vacuum*Isp_vacuum*g0*10^-6
Where... m_engine is the mass of the engine in kg, F_vacuum is the thrust of the engine in a vacuum in newtons, Isp_vacuum is the specific impulse of the engine in a vacuum in seconds, g0 is 9.807 m/s2. The equation is empirically derived so it's not perfect, but it works well enough for our purposes.

>What problems could designing injectors for an engine with gaseous propellants compressed at more than 30 bar have?
I'm not sure as I don't have alot of injector experience, but one problem I can forsee is that the properties of your gaseous propellants (pressure, density, temperature) may change significantly across the injector in accordance to the Ideal Gas Law. This can really mess with your mas flow rates if you can't properly predict this. Another problem with injectors in pressure fed engines in general is that if the combustion pressure may change dramatically due to random uneven propellant mixing resulting in pressure waves being sent back to your tanks which then affect feeding. I've heard pintle injectors are most resistant to this.

Here's a general overview of some injectors.
https://engineering.purdue.edu/AAECourses/aae539/2007/spring/handouts/InjectorLecture2.ppt

Note that most injectors are designed with liquid/liquid or liquid/gas propellants in mind so the details may be incorrect for gas/gas.

>>10575959
Also this...
http://www.propulsion-analysis.com/RPA/download.htm
While this won't give you information on injectors, this program will definitely help you design your engine. However, the free version is quite restrictive sometimes and it assumes ideal performance.

I hope this all helps, and good luck!

>>10575959
Wait! Got my engine mass estimation equation wrong!

m_engine = 0.3625*F_vacuum*Isp_vacuum*g0*10^-6

Sorry!

>>10575740
>an ignition failure
hypergolics don't have ignition failures, that's why they're hypergolic.

>>10575974
I think he meant ignition failures in the spectacular way not in the disappointing way.

Is it possible that, making a big assumption that SLS can make a 2020 launch, that it could actually beat one or both of the commercial crew initiatives to their first manned flight?

This is a hypothetical, so don't kill me for it.

>>10575959
Using your equation for engine weight I get a weight of around 40kg, if I want a TWR of 1.5 at sea level. That would leave 80kg for everything else, including pipes, fittings, valves, electronics, sensors, and a structure around it. Does that seem reasonable? Or is it possible I might end up with negative mass for the payload?
I have no clue about how much mass goes into all those things.

>>10575966
>>10575985
That's great, less than the mass I expected at first, around 20kg. 100kg for everything else sounds much better.

>>10575985
It would have to be a pretty light rocket, I'd definitely want to use COPV tanks and a carbon fiber or very thin aluminum shell, aluminum or even magnesium alloy for the structural components. Also 3D printing can help greatly reduce an engine's mass because you can design it in software to be filled with hollow spaces wherever structurally possible to reduce it's weight. Also it depends on what your engine is made of, obviously a steel bell will be much heavier than a copper bell if they're the same size so if your chamber pressure isn't so high that you need steel for it I'd switch to a lighter metal or alloy. Launcher's E1 is made of a copper alloy for example.
https://www.youtube.com/watch?v=7pXEf0wHU1Y

>>10575982
SLS may (unlikely) launch in 2020 but would NASA allow astronauts on the first test fight?

>>10576055
that's the working plan lol

The last two "anomaly" delays for SpaceX lasted about 6 months each for F9. I know they built several Crew Dragons but not sure if any are close to the capability to replace the lost one.

>>10575985
>>10575991
So a dry mass ratio of 24% (assuming that your rocket is still 500 kg in total)? I think maybe you're underestimating the mass of your tanks.

If you know your diameter of your tanks, and the pressure and volume of your propellants then you can calculate the mass of your tanks of a given material.

https://en.wikipedia.org/wiki/Pressure_vessel#Stress_in_thin-walled_pressure_vessels

Here's how to calculate the wall thickness of pressure vessels. A cylinder with ellipsoid ends would be the simplest to design as the wall thickness would be constant throughout.

>Does that seem reasonable?
Your values seem off by a bit. A 24% dry mass percent is still seems abit low for the kind of rocket that you're making.

>Or is it possible I might end up with negative mass for the payload?
Possibly unless you lower the DeltaV that you want in your rocket. 1 km/s seems reasonably low for a start.

>>10576018
>COPVs
I've had issues designing around them. It's hard to model them due to how complex they are and thus hard to make a mass estimation of them. Plus, custom ones can get expensive. I've had some good luck with tanks that are made out of Aluminum 6061.

>>10575913
You should read this. This was very helpful to me.
http://risacher.org/rocket/

>>10576062
Most of the COPV tank sites I've seen all share a similar estimate of their tanks being between 1/5th and 1/4th the weight of a conventional tank rated to hold the same pressure, even if you double that weight and assume the COPV will weigh only half as much as an all metal tank rated to the same pressure that would be quite a significant bit of mass savings.

>>10576072
Don't get me wrong. I completely understand the weight saving of COPVs. I even wanted them for my rocket, but I couldn't find a way to reliably model their mass. For now I'm sticking with metal tanks because they're just easier to deal with on a spreadsheet.

>>10576081
You could have a very small scale model made, so it's not so expensive and compare that with a small scale model tank made of AL6061, having the two physical things right there would provide a better and more realistic mass comparison than a model, so long as your scale works well.

>>10576055
>>10576057
No it's not. EM-1 will be unmanned.

I just meant I was wondering if it was theoretically possible they both launch around the same time, and the answer seems to be: yes.

Fucking hydrazines man... I guess this is why these tests exists.

Given SpaceX had multiple successful engine tests and a pad abort test under their belt, who wants to speculate that this anomaly is caused by unforeseen issues resulted from its previous mission + reuse?

>>10576153
could be salt water intrusion, could be testing procedure error. Could be wacky COPV magic, something never seen before like with AMOS-6.

What is assumed is that the N204 COPV violently exploded, annihilating the DM-1 capsule. This was after a couple seconds of the superdraco burn.

>>10576157
It's always the goddamn COPV isn't it...

>>10576164
It's inevitable when you're working with high pressure equipment that failures are most likely to happen either soon into a piece of equipment's life or at the very end of it's life. Sometimes some small impurity of metal or not-quite-cemented fiber is all it takes if your kit is operating at the higher end of it's tolerances.
https://www.youtube.com/watch?v=IYGjDvI13N4

this dude is the SpaceX Dir. Commercial Crew, Dragon Mission Dir.

>>10576164
COPVs are black magic. They're literally black.

Which type of rocket engine cooling would be easier for an amateur to design and build?
>Ablative
>Regenerative

I'd feel that ablative would be easier at first, but regenerative may be better in the long term.

>>10576203
take some spy shots up the ass end of a LE23000FC.
then do that

>>10576203
Ablative is easier but it's a one shot kinda deal, if you're starting with really cheap and fast to manufacture test chambers just to get a firm grasp of what you're doing then it would probably make more sense, but if you're already sure what you need and go straight to producing an engine you want to function then go regenerative because it can be used for multiple shots. I've been planning to make one for funsies and to start building my knowhow for a while now and I intend to design it in some 3D software and then get it metal printed, so I'll be going with a regenerative design.

>>10576228
Ablative seems like the more sensible choice for me then, since I've never built an engine before.

How big is the engine that you're making? What's it's throat diameter? The engine I'm making has a throat diameter of 55mm, but I think that might be too big, both for someone to make on their own and to 3D print (if I ever change my mind on it).

>>10573647
No you don’t... that’s not how delta v or orbit works, there is no advantage to arbitrary gateways, the only sane place for staging is LEO.

>>10576237
I honestly haven't even done calculations for it yet and I won't have regular access to 3D design software for a while yet, it's basically just an idea that's been nagging me for months now that I finally decided to do more than think about. I don't imagine it generating more than a couple hundred N of thrust, basically the size of an RCS rocket.

>>10576263
Alright. The program in >>10575961 is very useful if you haven't figured out how to do the calculations yet, or if you need something to compare to.

Good luck!

>>10575982
Dragon already beat SLS to the first flight and I don't see the first manned SLS flight beating anything

>>10576255
I like low polar lunar orbit personally
it means you have pretty hard-set windows for up and down, but whatever

>>10576302
Thanks for this, it's probably gonna take me a few days just to figure out what all of this does but I'm grateful. I'll add it to Bragg's Rocket Engines book, LPREs by Sutton and Rocket Propulsion Elements by Sutton and Rocket Propulsion by Barrere, so probably something in the range of 2500-3000 pages. My soul is departing the mortal coil a little bit just thinking about the slog I'm in for.

>>10575666
>metric
>in manufacturing
ha ha
no

>>10576393
Good luck! It's alot, but eventually you'll start to notice things that'll simplify rocket design.

I recommend "HOW to DESIGN, BUILD and TEST SMALL LIQUID-FUEL ROCKET ENGINES" by Rocketlab as a starting read. It contains lots of basic information that'll hopefully help you start out.

I study these things both in university (and later professionally, hopefully) and as a hobby, and I frequently visit /sfg/ (or /sg/ or /SG/ or whatever) so if you have a question then feel free to post it here and I'll try to answer it the best I can.

And don't fret if it seems too overwhelming, there's a reason why "rocket science" is commonly associated with difficult tasks.

Again, good luck!

>>10576255
>the only sane place for staging is LEO.
implying that hauling lox fracked from the moon into lunar orbit wouldn't be a game changer for spaceflight

>>10576421
if you can get it to lunar orbit, you can get it to earth orbit
the delta v increase is negligible

boom.

>>10576456
Where did you get this?
If you're "on the inside", then can you tell us if anyone got hurt from that?

>>10576457
99% sure he got it from here

https://twitter.com/Astronut099/status/1119825093742530560

>>10576457
no one injured, we've known that since the beginning

slowed and trimmed to the explosion

>>10576456
Those damn ULA snipers at it again

>>10576461
How was it known? Did SpaceX state that? I thought that they haven't revealed much about what happened yet?

>>10571573
It can't, it won't.

The worst is that Starlink and Starship are simply delayed indefinitely and SpaceX remains just another rocket company, albeit private.

>>10576467
"On April 20, 2019, an anomaly occurred at Cape Canaveral Air Force Station during the Dragon 2 static test fire," Wing Spokesman Jim Williams told FLORIDA TODAY. "The anomaly was contained and there were no injuries."

https://www.floridatoday.com/story/tech/science/space/2019/04/20/smoke-seen-miles-spacex-crew-dragon-suffers-anomaly-cape-canaveral/3531086002/

>>10576157
I bet it's the 3D printed SuperDraco.

I know a thing and two about metal 3D printing and they are a nightmare if corrosive - cough cough - materials find a turbomicrocrack.

If that fault is in SuperDracos, we are looking at least 9 month delay. Remember, this time around NASA is watching over their shoulder.

>>10576465
so that's it huh? We livin' in some kinda Star Wars™ Special Collector's Edition?

>>10576479
If the "countdown" heard in the video (original source has audio) is relevant, it sounds like it detonated at T-8, which should be well before the thrusters are doing anything at all.

>>10576479
then the valve would stop mixing tho

>>10571535
What do you guys think of VASIMIR?
Seems like a feasible quick and safe way to get to Mars.

>>10576495
I don't know much about the technical details of ion drives, but a problem I see with using them for a manned Mars mission is that they'll take a long time to get there due to the low thrust (even at "low gear"). However, maybe with the mass saved by going for a more efficient engine could be used to expand the living space for the crew so that they don't come down with cabin fever.

>>10576495
Interesting but very energy hungry, for a Mars shot you'd probably want a 4-500kW nuclear reactor to provide you with the necessary energy, at which point I'd probably just wrap the reactor into a conventional NTPR which can also passively power a set of stirling generators with it's waste heat.

>>10576495
mite b cool, but it needs a nuclear reactor to power it, and that's probably not gonna happen anytime soon

>>10576456
wow
it was, and then it wasn't
just like that

>>10571535
https://twitter.com/Astronut099/status/1119825093742530560

>>10576554
slowpoke

>>10576495
good in theory, bad in practice
Needs a nuclear reactor to function
nobody wants to do nuclear in space because green rock bad
if the public were to warm up to the idea, we might as well go for proper nuclear propulsion, skipping VASIMIR entirely

>>10576456
bad dragon explodes in this shocking video!

>>10576532
Cringe

I'm calling it. That dragon capsule flight is getting delayed by a year or more. There's gonna be an inquiry. Congress might even get involved. Screencap this.

>>10575859
>mankind progressing into the final frontier of space
>niggers whining about muh programs

https://twitter.com/GISRockstar/status/1119750407960584199

>>10571535
Earth is flat

I feel like reposting this. Can any anons tell me specific things about the Saturn V aft interstage(s) skirts Was there a separate thing that fell off between the S-II and the S-IVB? Between the S-IC and the S-II? Where is the "classic" footage really from and what does it depict?

ULA SNIPERS DID IT AGAIN!!!
HOW DID THEY GET AWAY WITH IT???

>>10576512
>>10576521
>>10576557
A nuclear reactor would make VASIMIR have such a terrible fucking TWR it would take literally years to get to Mars. The only viable option short of some lightweight fusion magic, is suuuuper lightweight solar film.

>>10576595
Do you consider reading comprehension and basic literacy to be beneath you?

>>10576600
What exactly am I missing?

>>10576586
Yea there were interstage "rings" that were jettisoned after the main engine(s) for the next stage ignited.
They contained a bunch of the electronics and carried some of the ullage motors.

Once the stage below was jettisoned, the small ullage motors would fire to provide acceleration and slosh all the fuel/oxidizer to the bottom of their tanks so the main engine(s) could ignite.

The camera film was mounted in canisters that were jettisoned and recovered from the ocean.

https://www.youtube.com/watch?v=-oILApXqPMI

>>10576595
Fusion will never be lightweight in the next 100 years.

>>10576616
Lockheed might disagree.

https://www.youtube.com/watch?v=UlYClniDFkM

>>10576616
I agree, that's why I said magic. Even looking at optimistic plans like SPARC that I would rate having a very high chance of being the first generation of commercial reactors, they are still going to be heavy as FUCK.

>>10576619
>pls gib more taxpayer funds
>t. LM

https://www.nasaspaceflight.com/2019/04/spacexs-crew-dragon-spacecraft-anomaly-static-fire-testing/

>>10576619
This is a complete meme. It‘s all wild, fantastical claims and zero information to back it up. There‘s no reason to believe Lockheed scientists magically know physics and engineering solutions to allow reactors a tenth of the size of what‘s being worked on by other people in the field who publish their findings.

>>10576642
Hence I said "Lockheed might disagree", not "I might disagree".

God damn it why does space have to be so hard. If ol musky fails i hope bezos takes up the challenge.

>>10576659
I want Blue Origin to do good stuff but after watching the pace of SpaceX, Blue Origin is like a fucking joke. They have been established for about the same length of time and have still not managed to do anything other than launch a tin can up and down.

>>10576659

No. Bezos should be shot dead. We should openly conspire to murder Jeff Bezos on this web forum. This has nothing to do with his space interest, Bezos should simply be killed, that's all.

>>10576641
>https://www.nasaspaceflight.com/2019/04/spacexs-crew-dragon-spacecraft-anomaly-static-fire-testing/
>Then, the company was able to prepare the capsule for this weekends testing just six weeks after the same Crew Dragon spent around an hour in the corrosive saltwater environment following splashdown from the Demo-1 mission.
Wait, so was the capsule that went boom the same one that was recently in space and the Atlantic? That leaves the possibility that the anomaly was caused by reuse open, and Crew Dragon could still be certified on schedule as long as it's not reused. The most important thing though is how quickly they can figure out what the fuck happened and resolve it. For all we know now someone could have just fucked up testing procedures.

>>10576673
Vulcan is using their BE-4 engine.

>>10576683
>Wait, so was the capsule that went boom the same one that was recently in space and the Atlantic?
Literally the first sentence of the article:
>>Just six weeks after splashing down in the Atlantic Ocean following a successful Demo-1 test flight, the same SpaceX Crew Dragon spacecraft was set to perform multiple static fire tests on Saturday to verify that the capsule’s propulsion systems were functioning properly ahead of an inflight abort test planned for the summer.
>>the same SpaceX Crew Dragon spacecraft

>>10576688
Yes they have an engine too but that's not the same as actually flying shit.

>If we store N2O4 in the same tank as the hydrazine we‘ll save tons of space!
>Oh! Oh no!

>>10576712
It doesnt matter

>>10576744
It kind of does.

>>10576456
This is why you must put your trust in those who can. Boeing. The American way to space.

>>10576755
Didn‘t their capsule fail vaccuum testing spectacularly? Seems just as bad. Maybe worse.

>>10576772
It will become obvious the minor issues encountered by Boeing are of a different magnitude than the catastrophic event that happens to Spacex.
The reactions both from officials and the public will make that clear as the story unfolds in the coming weeks.
It is entirely possible Spacex faces termination of contract after this disaster that could have easily claimed lives of American astronauts.

>>10576781
I mean, NASA has deliberately killed at least a dozen people, and we continue to fund them.

>>10576781
>Vacuum chamber failure
>Astronauts reach space and die

Vs

>Abort thruster failure
>So long as the rocket doesn't randomly explode, astronauts are fine

>>10576755
>747max

>>10576793
except the abort failure CAUSED the rocket to explode.

>>10576846
There wasn't even a rocket there you moron

>>10576828
>747
brainlet

After SpaceX capsule failure SpaceX shills are on suicide watch.

>>10576463
good good

Well, good thing it exploded now and not during in-flightaborttest.

>>10576848
>quibbling over pedantic word choice when the meaning is clear
I'm glad they tested, because this would've killed any astronauts in the capsule. Just like the Boeing vacuum chamber failure would've.

Well, good thing it exploded now and not during in-flightaborttest.

>>10576755
Boeing! Our hypergolics don't go bang, they just go into the crew compartment!

Video of Crew Dragon exploding:
https://twitter.com/Astronut099/status/1119825093742530560

>>10576781
But failures would have killed astronauts though. I mean.. these are called "tests" for a reason.

But both failures would have killed astronauts though. I mean.. these are called "tests" for a reason.

>>10576828
Customers refused to buy the needed safety systems offered by Boeing.

>>10576479
The engines weren't even close to firing when the explosion occurred.

>>10576995
Also, the explosion in the video didn't come from the direction of the SuperDracos and they are contained within armored bays. All the existing evidence points to a fuel tank rupture or COPV issue.

>>10576495
Currently it doesn't work for more than a few seconds, on the ground with unlimited power budget. Translating that to deep space use with months of continuous firing and very constrained power supplies makes it the exact opposite of feasible and quick. In fact despite the higher Isp VASIMR would be slower than chemical propulsion for any mission in the inner solar system and asteroid belt all the way out to Jupiter, because VASIMR has such low thrust and requires a very big (and thus heavy) power supply. Any figure you've seen about VASIMR allowing ~1 or 2 month trajectories to Mars is fantasy; that would require a power supply capable of producing hundreds of watts per gram of mass, which is way beyond what even thin film solar can do at peak absorption (getting closer to the Sun hits your panel with more photons but also heats it up, and at a certain point the efficiency loss due to panel temperature overcomes the increased flux rate and the panel starts producing less power).

Not much point in going on about the SpaceX failure until we have more details about exactly what failed, what the goal of the test was, and what condition the reused hardware was in.

>>10576997
I don't understand. The fuel tank *for* the super dracos ruptured?

>>10576495
Might be good for ISS boosts, but it's so energy hungry that it'll need a set of batteries to store up enough energy for a burn.

>>10576576
>Congress might even get involved.

>>10576576
Possible. It will all depend on the nature of the explosion. It it was due to the refueling equipment for example, then things might not be so bad.

>>10576595
>lightweight fusion magic
Literally never, fusion will ALWAYS be heavier than fission simply due to the nature of the reaction. Even if you had some magic breakthroughs in magnet technology, plasma confinement, and light weight power-to-electricity conversion, you would still be able to simply swap out the fusion plasma for a fission plasma consisting of vaporized uranium or plutonium and get a VERY significant increase in power output simply from the fact that the energy that the fusion reactor needs to use to keep the fusion reaction running is just not necessary to keep the fission plasma burning, and thus can be routed away as useful power instead. You'd also get further power increases from there since you can dump way more fuel into the reactor at once than with a fusion reaction without overwhelming the reaction because you don't have to worry about accidentally cooling the plasma below the fusion temperature.

>>10577012
Probably the wet dreams of downselect to one provider are going to happen.

>>10577017
A lot of people think fusion is magic and one of the most obvious things it doesn't need in space are radiators.

>>10577009
Looks like it, yeah.

>>10577033
Are you saying fusion doesn't need radiators, or are you saying other people think fusion doesn't need radiators? Because fusion definitely requires radiators, both in space and on the ground.

>>10577049
SpaceX are having trouble with fuel tanks if that's the case.

This would be the third vehicle loss due to a fuel tank rupture if true,

>>10577061
COPVs and fuel tanks are not the same thing

>>10577061
It'd be their second direct COPV-caused failure, the other being AMOS 6. CRS 7 on the other hand failed because of a weak strut meant to hold down a COPV bottle; when the strut broke, the bottle shot upwards and burst when it hit the bulkhead, popping the main propellant tanks. AMOS 6 failed because of frozen oxygen in the carbon fibers surrounding the COPV. This new failure would have to be of a different mode entirely, because the COPV bottles aren't immersed in LOx and weren't being subject to high G loads. My bet is on some kind of cracks or weakening of the bottles or plumbing during splashdown. As the main tanks were pressed for the upcoming engine burn, the pressure caused a crack to propagate and burst one of the bottles, which would have damaged a separate bottle holding the other propellant and caused a hypergolic fire to star, blowing the capsule apart.

>>10577067
fuck

>>10576993
>safety system as a DLC

>>10577074
The best case scenario for SpaceX here is that the anomaly was the result of undetected salt water corrosion, this kills D2 reusability and puts SpaceX's Mission Assurance department under heavy scrutiny, but does not have to lead to a major design change which incurs significant delays.

>>10576857
Just realised after posting. But you get the idea

>>10576993
>Boeing agreed to sell airplanes without needed safety systems.

>>10577095
>undetected salt water corrosion
How would they even determine this, now that all that's left are smithereens?

Both Crew Dragon and Starliner are inherently unsafe, which was obvious from the start. They have high-powered thrusters with huge chamber pressures inches apart from the crew, doubling as a launch escape system. Starliner doesn't use MMH/N2O4 and its thrusters are located a bit farther away, so in theory it should be a bit safer, but in both cases if something goes wrong LOC is pretty much guaranteed.

Orion, on the other hand, only has a small orbital thruster located much farther away from the crew. It's literally ~40 times weaker, and it's a single engine. In case of its RUD, the worst you'll probably have is Apollo 13. The classic launch escape system is also much safer. It's a single solid booster, which is much simpler and isn't prone to spinning due to de-synchronized thrusters.

By the way, here's the Starliner's launch complex escape system, which is also unsafe by design.
https://www.youtube.com/watch?v=u31z5gKJWrE
In case of emergency, workers/astronauts have to tie themselves (which takes time) and slide down the zip line. Yeah... excellent design for a collapsing launch tower.

>>10576993
>burgers will defend this

>>10576463
Aftermath video
https://youtu.be/6fKRHDBC1tM

>>10577169
>All those dislikes

>>10571535
Evidently Zerohedge will stop at nothing in their campaign to bring down Musk.

>>10577175
Well the video seems to show nothing about the accident. Just some shots of the launch pad?

>>10577175
This is the same guy who filmed AMOS-6 exploding, SpaceX got him kicked out of his old filming spot because of it...

NEWSPACE IS SEETHING!!!!!

>>10577198
Guess that capsule really was expendable after all?

Oldspace Safespace.

The Way Things Always Worked(tm).

>>10577222
>that dichotomy
You don't have to be oldspace to make safe decisions, though.

>>10577222
I remember the space shuttle.

So safe!

ormal overview meeting on Tuesday to determine an investigation path. Gerst himself just sent the e-mail to the team.

>>10577260
source?

>>10577260
*Formal

>>10577261
NASA guy on L2

SpaceX can kiss the flag goodbye. If they can get Dragon 2 to the station by the end of 21 they'll be lucky.

>>10577009
no, the general fuel tank for Dragon
both the draco maneuvering thrusters and the super draco abort thrusters draw from the same tanks

>>10577298
interesting

>>10577149
Because all that's left _isn't_ dust.
But I don't think they want to spend a year putting together a jigsaw puzzle in a hangar. Hopefully telemetry can give them some faster clues.

>>10577334
>But I don't think they want to spend a year putting together a jigsaw puzzle in a hangar.

They should release all parts in some overview to the internet and have some 4chin autists spend their NEET time on figuring it out.

>>10577149
You'd be surprised how much info you can get from the tiniest bits of input in space industry. Root cause analysis is done all the time with all kind of mishaps and all kinds of spacecraft, and it's usually pretty tricky and involves quite a bit of simulation/testing. IIRC they had to do a non-trivial acoustic simulation of the entire structure to locate the origin of AMOS 6 explosion based on the accelerometer data they've had, and that was only a small part of the analysis.

>>10577149
There are ways.

>>10577362
>Root cause analysis is done all the time with all kind of mishaps and all kinds of spacecraft
Speaking of which, InSight's probe still stuck, and I'm extremely interested in their thought process. But rockets are easier to shitpost about.

>>10577244

>>10577074
Why are these bottles next to each other?
You'd think you'd want as much distance between the two as you can get.

>>10577382
lol.

NASA-MANAGEMENT-LITERALLY-COMMITTED-MANSLAUGHTER-ON-12-PEOPLE/10

>>10575913
Oh my, I thought I calculated kg of gas that fit into the tank, but I actually calculated grams. That's why it seemed too good to be true.

>>10577390
>12-PEOPLE
Where does that math come from?

>>10577395
2 shuttles full of astronauts. Maybe my math is off. w/e.

>>10577396
Maybe you should look up the correct crew size.

>>10577404
14. fine.

So SpaceX wont launch a crewed mission in 2019 by the looks of it, it will be in early/mid 2020.

Scott Manley mentioned that both the Dragon and the Starliner use liquid fueled engines for the emergency engines instead of solid fueled ones like on the Soyuz. Why the choice for liquid fueled VS solid fueled? Higher thrust ratings?

>>10577387
There’s only so much space within a rocket. You have to squeeze everything in, which is even harder when you’re dealing with spherical/cylindrical tanks.

>>10577437
Controlled thrust.
Once you light an SRB it will burn, you can't control how long and how much thrust to use.

>>10577390
>he forgot about Apollo 1

>>10577453

Is such fine control even needed for a launch abort system thruster?

Real talk: Ban hypergolics and COPVs.

>>10577472
Is is for SpaceX since they want to do propulsive landings with their capsules.

>>10577462
Nah, was specifically referring to shuttle stuff. Also i kind of forgive Apollo 1 more since there was somewhat of a national security aspect of beating the russians in space tech.. but still sucked.

>>10577334

Is that a real photo of the aftermath?

Wow.

>>10577474
stainless steel is looking really appealing right about now

>>10577480
of Columbia

>>10577476

Werent those cancelled in favor of parachutes?

>>10577487
Because NASA didn't want propulsive landings. I think SpaceX still wants propulsive landings so they can avoid sea water corrosion.

>>10577487
yes

>>10577010
Nothing wrong with that, batteries are better than ever.

>>10577492
>I think SpaceX still wants propulsive landings so they can avoid sea water corrosion.
They won't do propulsive landings with D2. Pushing landing legs through the heatshield was too hard of a problem.

>>10577492

I bet we would not have this problem if NASA agreed to stick to the original plan. Not only would Dragon avoid seawater exposure during landing (and parachute landing touchdown stresses), but the thrusters would be much more thoroughly tested in real flight conditions since they would be used in every flight.

>>10577516
The Constellation plan was good, Obama fucked it up desu.

>>10577523

Better than SLS at least.

>>10577523
Constellation is the sls.

>>10577523
You mean like Ares I? That rocket had an extremely dangerous launch abort scenario. Plus Constellation was tied to Shuttle hardware which has loads of nasty political issues with that.

>>10577510
TKS had a hatch in its heatshield in 70s, and flew just fine. (admittedly, nobody in soviet space program liked this hatch as it was considered unsafe and was a huge PITA to design)

>>10577516
Yes. But then you'd have a lot more delays with certifying the engines and figuring out how to make landing legs stick out of the heat shield without damaging it.

>>10577510

Couldnt the legs go around the heat shield, extending from the sides?

>>10577523
Only on paper. It wasn't realistic. Looking at SLS progress, what makes you think they could run an order of magnitude larger program?

>>10577545
This is not KSP, the air/plasma flow is fairly complex and there's little difference between two solutions in practice. Also, you don't enter strictly bottom-first in a roll-controlled gliding reentry, you enter at an angle.

>>10577364
The world's most macabre jigsaw puzzle

>>10577545
I know that landing legs weren't the sole technical/regulatory challenges they have to overcome, but I always wondered why couldn't get around that by just landing directly on the heat shield, and maybe in a giant sandbox to soften it as well.
I'm mean sure the heat shield will probably have to be replaced, but in return you avoid salt water intrusion to the capsule and gets much quicker access to returned cargo.

>>10577556

Or land in a pool of distilled water?

>>10577556
>and maybe in a giant sandbox to soften it as well
having the abrasive sand flying around a delicate spacecraft is probably not a smartest idea either

>>10577556
>I know that landing legs weren't the sole technical/regulatory challenges they have to overcome...
I think a simpler solution would be to mount the legs behind the shield, drop the shield after reentry, and then extend the legs for landing. I mean, the shield ablates so its going to be taken off and replaced anyways.

>>10577562

Holy shit, SpaceX droneship with a giant pool when?

This is actually an interesting idea, lol

>>10577566
>drop the shield after reentry
An additional separation event is generally a stopper in rocket/spacecraft design. Literally nobody wants that, separations are to be avoided.

>>10577573
>Dragon lands in water
>Which is in a pool on a droneship
>Which the droneship is on water
>Which is in a even bigger pool on an massive droneship
Brilliant.

>>10577555

>and there's little difference between two solutions in practice

How so? The legs wont have to go through the shield, thus solving the problem.

>>10577575
I mean, the Soyuz does something like that with their heat shield and I don't recall them having problems with it. Then again it IS the Russians, they'd probably react to a hydrazine leak with "Just don't breathe through your nose".

>>10577578
It's elephants and turtles all the way down.

>>10577582
>Then again it IS the Russians, they'd probably react to a hydrazine leak with "Just don't breathe through your nose".
Akschshschually, Russians were the ones to avoid hydrazine in human spaceflight at all costs. LK/Soyuz use hydrogen peroxide instead of UMDH/MMH for exactly this reason. Only Americans and Chinese allowed hydrazine for human spaceflight.

Proton and converted ICBMs like Rokot were hydrazine-fueled, but they haven't ben used in human spaceflight. Yet it was Titan II, an American missile, which killed 53 people in a hydrazine leak.

>>10576398
>t. lithobreaking on Mars

>>10577607
No wonder "green" propellants are being researched now. Hopefully those nasty hypergols will be phased out soon.

>>10577607
The Russians aren't completely faultless with hypergols, they had the Nedelin disaster after all.

>>10577607
Talking of hydrazine accidents, you've forgotten to explain why the Soviets never launched humans on a hypergolic fueled booster...

http://www.pravdareport.com/history/115503-R16_rocket_explosion/

>>10577607
>Yet it was Titan II, an American missile, which killed 53 people in a hydrazine leak
What about the N1? Russians and ruskie bootlickers tend to forget about their own disasters very easily

>>10577628
This poor motherfucker.

>>10577623
>>10577626
Nedelin disaster had nothing to do with the type of fuel, it happened due to poor safety culture at the time, and accidentally starting the 2nd stage engine while there were still people working on the missile. They completely reworked their safety procedures after that catastrophe from scratch, across the entire industry.

>>10577628
I don't know, what about N-1? And how it's related? It was kerolox-powered. I've just answered to this >>10577582 incorrect assumption that russians had anything to do with hydrazine in human spaceflight.

>>10577628
Your pic isn't N1, genius.

>>10577642
"Пpиcoeдиняйтecь к кocмичecкoй индycтpии, cкaзaли oни. Этo былo бы cлaвнo для paбoчих вceгo миpa, cкaзaли oни."

Hopefully Google translate doesn't mess this up.

>>10576993
>burgers sell unsafe airplanes on purpose
Oh, say, can you see...

>>10577555
Do you need to extend the legs so early though? You can probably afford to slow down a bit more before landing to give time for legs to extend

>>10577684
that assumes that they can be hidden to not disrupt the airflow, and the secondary (non-ablative) heat protection

I also imagine they can fry and/or disrupt the superdracos exhaust quite a bit when deployed from the side

>>10576993
All they sold was a way to see that the AOA sensors were fucked up. MCAS still only used one sensor, and you still had to know MCAS was there and what it did.
So the DLC didn't even work, sorry no refunds!

>>10577690
Fuck, that's true
B-but booster landing legs manage, what's so much harder here?

>Dragon blows the fuck up during testing
>Zero crew present
>People are freaking out
This is a good thing idiots. This is why they do these tests, so they can find these problems before the a crew gets a RUD.

This explosion pretty much means the manned launch in summer is scrubbed right?

>>10577693
Booster legs don't have to deal with re-entry from orbital speed.

>>10577697
>This is a good thing idiots. This is why they do these tests, so they can find these problems before the a crew gets a RUD.
If you think about it, SpaceX has been getting all sorts of weird problems happening in ways that nobody gets hurt, and they can fix it to not happen again. Okay, Zuckerberg lost his Bookface satellite, but fuck him.

>>10577693
booster legs don't reenter from orbit, they are massive, and the exhaust goes from under the rocket (mostly)

dragon is pretty limited by mass in comparison and the superdracos exhaust goes along its sides

also, superdracos are MASSIVELY overpowered for the spacecraft of this size, to provide both launch escape and propulsive landing, all of this at an angle (reduced total thrust)

>>10577697
"We fail down here so we won't fail up there."
More people need to learn that.

>>10577699
>poor little New Shepard Beta on the left watching all those Chad launches getting into orbit and beyond

>>10577774
Obligatory

>>10577938

>I hate white people. We need UBI to give all our money to blacks and immigrants.
What did Musk mean by this?

>>10577151
>slide down the zip line
That is fucking hilarious.

>>10578263
>>slide down the zip line
>That is fucking hilarious.

Vs having your pod be at tiny rocket?
Not that strange actually.

>>10578302
Tiny rockets work really well. Soyuz has saved lives because of it. If the shuttle had had a crew escape pod, Challenger and Columbia would not have neded in death. How is a stupid zipline supposed to be fast enough to escape an exploding rocket? What about in-flight failure?

>>10578309
>What about in-flight failure
Pray to your god.

>>10577483
>stainless steel is looking really appealing right about now

We gonna have another delightfully counterintuitive moment?

>SpaceX could be delayed past 2021 in the worst-case scenario
yfw SLS flies before manned crew dragon

>>10578434
SLS was supposed to fly before commercial crew since it was meant to launch in 2017. So the SLS got so delayed that the only way it can catch up to a program that started years after it and has less budget than it was if this smaller project suffered a catastrophic failure. Also, SLS may not meet its 2020 goal if I recall correctly.

>>10578446
>Also, SLS may not meet its 2020 goal if I recall correctly.
Thats pretty much a given at this point after we the news came out that they have to redo the software part of the SLS project because everybody left because they refused to skip safety steps.

>>10578263
Hey now, nasa abandoned a pretty nice rocket concept in favor of the SLS because it required building a fucking rollercoaster to get the fuck away from the rock if shit went south.

>>10578534
>everybody left because they refused to skip safety steps
Let me guess, this was at Boeing, right?

>>10578597
yes, but the push for skiping safety tests is probably also because they are finaly waking up to the fact that if they dont get results soon the cashflow will stop.
They really have underestimated the private rocket companies and how fast they are growing and now they are caught with their pants down.
I really hope all this will create a new wind for nasa and a way to clean out some of the "oldspace" money sinks.

>>10578434
>yfw Starship flies before manned crew dragon
ftfy

Does anyone have the equation for an ideal bell nozzle? I have tried looking for it, but I couldn't find a simple way to model the shape.

Thank you in advance.

>>10578534
whoever told you that's bsing you. there was no such event.

>>10579115
I have my doubts over if it happened too, but the fact is that SLS is very likely to not meet its 2020 launch goal.

>>10577492
>so they can avoid sea water corrosion.
or cause it'd look cool as fuuuck

>>10576100
Oh, it's completly possible.
But
This is a multibillion dollar boondoggle built as a fustercluck of congressional lobbying
I want to go to space as much as the next buy, but no way in hell anyone smart enough to be astronaut material would hop in that thing.