
If Rockets Were Transparent [video] - vdfs
https://www.youtube.com/watch?v=su9EVeHqizY
======
hoorayimhelping
Red is kerosene, blue is liquid oxygen, orange is liquid hydrogen, the fuel
that looks like fire is solid fuel (think compressed gunpowder).

Left to right: Saturn V, Space Shuttle, Falcon 9 Heavy, SLS (still under
construction).

2:22, you hear Neil Armstrong say "inboard cutout," that is the center engine
shutting off to limit the thrust, and therefore G-forces the astronauts felt.
As fuel ran out, the rocket stack would weigh less and so the rocket would
push harder. By the time the main engine cutoff, the Saturn V was pulling 4
and a half Gs.

Also, just noticed the SLS keeps its launch escape tower (the big needle on
the top of the rocket - see this:
[https://www.youtube.com/watch?v=AqeJzItldSQ](https://www.youtube.com/watch?v=AqeJzItldSQ))
- this wouldn't happen in a real flight. The flight plan calls for ditching
than when it's not longer useful - you can hear the Apollo 11 call saying,
"tower jettisoned."

~~~
bfieidhbrjr
So the SRBs don't burn from the bottom up?

~~~
SAI_Peregrinus
Nope, inside out. They're hollow, and the top section has a star cross section
rather than cylindrical. The goal is to keep an overall constant pressure for
the entire burn time.

~~~
matt-attack
If you ever used a toy rocket as a kid, the engines had a long hole down the
middle. Apparently the Space Shuttle uses the same idea:

[https://www.siriusrocketry.biz/ishop/images/EstesStandardEng...](https://www.siriusrocketry.biz/ishop/images/EstesStandardEngine.jpg)

~~~
dTal
Estes black powder motors are in fact end-burners:

[https://farm8.staticflickr.com/7457/12472921013_aa92200267_k...](https://farm8.staticflickr.com/7457/12472921013_aa92200267_k.jpg)

------
asciimike
One of the most amusing books I've read on the subject is "Ignition! An
Informal History of Liquid Rocket Propellants" (PDF:
[http://www.sciencemadness.org/library/books/ignition.pdf](http://www.sciencemadness.org/library/books/ignition.pdf),
Amazon link: [https://amzn.to/2WXzWcp](https://amzn.to/2WXzWcp)), which
discusses how science used to be more fun and chemists basically just mixed
lots of super dangerous chemicals together all the time to see what worked.

Related-ish: [https://www.discovermagazine.com/environment/in-russias-
spac...](https://www.discovermagazine.com/environment/in-russias-space-
graveyard-locals-scavenge-fallen-spacecraft-for-profit) (again, most rocket
propellants aren't exactly great for you).

~~~
umvi
> which discusses how science used to be more fun and chemists basically just
> mixed lots of super dangerous chemicals together all the time to see what
> worked.

Reminds me of the book "Uncle Tungsten", which I highly recommend.

------
KineticLensman
Nice. If I could change one thing it would be to rotate the different vehicles
as they ascend to emphasise that they are trying to achieve high horizontal
speed rather than just altitude. That means they are in orbit when the engines
cut off, otherwise they would just drop back to Earth.

~~~
SlowRobotAhead
Which to me is why it’s crazy these have so much fuel and burn so hard - while
Virgin’s “plane” gets as high as it does.

Virgin isn’t trying to leave orbit, but it’s still really an interesting
comparison to rockets.

~~~
dotancohen
Orbit requires about 7.8 km/s. That an "s" on the end, not an "h". Orbital
vehicles travel almost 8 kilometers every _second_ so as to miss the Earth
when they fall.

You're right, Virgin's plane gets very high, about one quarter as high as the
international space station. But some missions require actual orbit.

~~~
mnw21cam
Yeah. See the first two pictures in [https://what-
if.xkcd.com/58/](https://what-if.xkcd.com/58/) for an illustration. It only
takes a small amount of fuel to reach space. It requires a huge amount to
reach orbit.

------
SwiftyBug
What's the purpose of the plane-like rocket? It looks like something that was
built to fly in an atmosphere, but it's designed to be in space. Does it
eventually re-enter the atmosphere, thus the need to be able to fly in it?

~~~
macksd
[https://en.wikipedia.org/wiki/Space_Shuttle](https://en.wikipedia.org/wiki/Space_Shuttle)

There's a few things that led to this. Culturally, the American space program
has tended more towards the ideal of the "hero" astronaut than others, and
there's been some tension between the technical/automated approach and the
pilot-astronaut approach to things. I see this as an extension of that. They
even considered having pilots manually control the pitch, etc. of the rockets
on their way to orbit with the pilots hand on a joystick just following a
"recommended" course to orbit.

NASA had explored various ideas for very precise landings, believing that to
be useful especially for rapidly-reusable aircraft. There was very serious
consideration to having Gemini capsules land with a glider and the astronauts
facing forward similar to an aircraft:
[https://en.wikipedia.org/wiki/Advanced_Gemini#Gemini_Paragli...](https://en.wikipedia.org/wiki/Advanced_Gemini#Gemini_Paraglider).

~~~
pjc50
The Space Shuttle was massively handicapped by the Air Force giving it
unreasonably difficult requirements. They were the ones who wanted it to be
most plane-like. Especially the requirement to take off, capture a satellite
(friendly or hostile), and land again at Vandenberg in a single orbit.

~~~
Robotbeat
The Shuttle looks inefficient until you try to design a multi-purpose
spacecraft that can return large payloads from orbit. If you tried to do the
same thing with a capsule, it’d also be pretty huge and expensive.

And for as expensive as Shuttle was, it had a pretty powerful capacity that
mostly made up for it... look at the cost per kg of payload on Commercial
Resupply Services to ISS and the cost per seat of Commercial Crew. Shuttle
could do about 10 tons of pressurized cargo and 6 (and sometimes even 8) crew,
plus about that much down-mass capability, & another robotic arm and airlock.
The cost to replicate that capability 1-to-1 is about the same... Of course,
that level of capability wasn’t needed as much after ISS was built, and
Shuttle couldn’t stay on-orbit for longer than a couple weeks or so. And most
importantly, Shuttle was stuck in LEO and could never venture farther and
lacked safety features like a launch abort system and was too expensive and
unsafe to justify for standard commercial launches in the 21st century.

Not bad for tech developed in the 1970s, tho. The only individual spacecraft
(besides Buran) that is comparable in scope and ambition and flexibility is
SpaceX’s Starship.

~~~
nickik
The Commercial Crew and Cargo programs are far, far cheaper then the Shuttle.

The Shuttle was one of the most expensive ways of getting to Space BY FAR. As
every flight had to be a human flight.

Having a vehicle that could do everything, even when 90%+ of the mission only
required a small part of the capabilities made it untenable.

With one simple Dragon like capsule you can replicate both crew and cargo up
and down transportation for most of the things you need. If you need to
transport big pieces, you can just put them on top of a rocket by itself as
most station outside of part of the ISS were built.

The way the Russian designed the Buran and Energia system was far more capable
of doing all those things. This was mostly because most in the Russian space
flight program thought that Shuttle was a terrible idea and they didn't want
to handy cap their next generation rocket to a Orbiter.

Had the Soviets not collapsed, their launch capability would have outstripped
the US by 4x.

> Of course, that level of capability wasn’t needed as much after ISS was
> built

It wasn't needed to build the ISS in the first place. Its rather that the ISS
was designed TO REQUIRE the Shuttle.

It would have been far cheaper to use the cheapest commercial rockets and the
Ariane to build ISS.

> Not bad for tech developed in the 1970s, tho.

A lot of the technology was great, but great technology doesn't make a great
product.

~~~
Robotbeat
What is the price per ton of pressurized cargo for commercial cargo? Price per
seat with commercial crew?

~~~
nickik
SpaceX Commercial Crew will cost 55M per seat for NASA. Add to that need need
to amortize 2.3 billion in development financing that NASA has given out
(includes 2 astronaut flights). SpaceX can sell the other seats on the
capsule.

They payed almost 90M per seat for Soyuz at least in the last couple.

In comparison, the program cost of Shuttle per flight was 1.5 billion per
flight. They would almost never fly more then 4 people on those flights (just
as Dragon can also take 7 people, but NASA only takes 4). And the Shuttle was
not getting cheaper and the flight rate was not getting faster.

NASA of course has 2 contractors the other was 4.2 billion and the per seat
cost is somewhat higher, not sure exactly with the numbers, like 70M or so.

What the per seat cost overall cost are we will see over time. After the
initial maximum flight Commercial Crew contracts run out, NASA can renegotiate
after that initial contract and likely get a lower per seat price then.

We will see what the end-to-end lifetime per seat cost are for NASA.

I can't give you perfect numbers for perfect Cargo without a lot of research.
It depends if we are talking CRS1 or CRS2 contract and there are 3 providers
that are all somewhat different, different proportions of up-mass, down-mass
and other capabilities, some that the Shuttle didn't have.

The Shuttle could theoretically transport a huge amount of unpressurized cargo
but if you are not building a Space station its hard to actually utilize that
space fully. So an analysis would have to include the actual payload and so
on. That is getting to complex here.

What NASA values seems to be having much less risk on one system. Having
different vehicles on different rockets and being able to deliver what they
want when they want it and get it back when they want it back.

~~~
Robotbeat
SpaceX charges about $46m per ton of upmass. So for the ~10 tons of upmass per
mission, that's $460m. (Plus I think Dragon is pretty volume constrained
compared to the MPLM that NASA used with Shuttle.)

SpaceX's price per seat is $55m, Boeing is $90m, same as Soyuz.

And it's _false_ that "[t]hey would almost never fly more then 4 people on
those flights", as you can see from the list of Space Shuttle missions:
[https://en.wikipedia.org/wiki/List_of_Space_Shuttle_missions](https://en.wikipedia.org/wiki/List_of_Space_Shuttle_missions)
(5th column lists number of crew... To ISS it's usually 7 crew but sometimes 6
and only one time 4). The reason why is they could do a "crew surge" where
they could get a whole bunch of work done on Station for a couple weeks and
then the extra folk would go back down.

And it's false that Dragon can now take 7 people... They switched to 4 because
of the need to change the orientation of the seats to ensure safe splashdown
and the 7 seat configuration no longer fit. There were some configurations of
Shuttle that would've allowed like 74 additional passengers, too, with a
passenger module, but they never flew that variant either.

So again, 7 seats at Boeing's $90 million would give an additional $560
million per mission (or $385m for SpaceX), for a total of $1.1 billion (or
$845m), not counting the capaiblity of the extra airlock or the extra robotic
arm for servicing capability, plus the ability to take up full ISPR racks or
return large pieces of external cargo or...

...So again, even with the $1.5B figure (which includes a ton of overhead at
KSC and JSC and elsewhere that would probably have to be covered in some other
way), it's still pretty competitive with commercial crew. And that's not
counting the NASA side of the commercial crew program, which is substantial.

So I'm with you on commercial crew and cargo being good. I think two or more
providers is a more robust system, and I agree it would've been possible to
build a big space station without Shuttle (the Russians did it). But the more
you dig in to Shuttle's capabilities, the more expensive it looks to
replicate. Shuttle really wasn't that bad considering how compromised the
design was by zipcode engineering and inability to effectively cost share with
commercial or military stuff (later on) and being essentially a traditional
government contractor run system.

...the all-in price per launch of Shuttle may have been about $1.5billion, but
the marginal price was around $500 million. If they had ever used that 74
passenger module (plus 6-9 crew), that would've been a marginal price per seat
of just $6 million... Not too bad, really.

But it was never cheap enough or robust enough to launch often enough to
ensure safety without launch abort. Hopefully Starship will change that,
enabling a marginal price per seat of something like $100,000 for a trip to
orbit...

~~~
woodandsteel
Does your cost analysis factor in inflation?

------
g3e0
This really makes it easy to see that the SLS (far right) is derived from the
space shuttle, with the orbiter removed and the payload placed on top instead.

~~~
0xffff2
It totally does. I knew this fact already in the abstract, but the imagery in
the video really drives home at a more intuitive level just how similar they
are.

~~~
dotancohen
I'm sure that helped reduce the costs and timeframe associated with developing
and building it, then.

------
onemoresoop
I enjoyed this with my 2yo son. He loves rackets and calls them Kiko.
Surprisingly he had the patience to watch the video till the end:)

Thinking back, I was quite fascinated by rackets and only when I was 7-8 did I
get across a book on rockets with very colorful fold out posters in it. I
think it’s great to have all this educative material on youtube, I will curate
some cool playlists for him to watch and learn things.

------
ardy42
The Saturn V and SLS engines burn for significantly longer than the Falcon 9
Heavy's. What's the significance of that? I assume it means they can lift more
into higher orbits, but I'm not sure.

~~~
oconnor663
The Saturn V and the SLS are as big as they are because they're designed to
carry astronauts to the Moon (or farther). I don't think the Falcon Heavy can
do that without using multiple launches and meeting / refueling in orbit.

~~~
Robotbeat
Falcon Heavy could do a single-launch loop around the Moon with Dragon.

------
d883kd8
Very interesting for me to see how much shuttle legacy is present in the
planned SLS. I knew it was using the same engines but based on the timing here
it seems to follow a very similar flight plan with the boosters jettisoned at
the same time and the 1.5 stage running out around the same time too.

------
marmshallow
I'd also love to see a comparison of the rockets' altitude & velocity thru the
launch

------
wayneftw
I don't know anything about space or rockets, but...

Why is a car housed atop the third rocket? You can see it around 4 minutes
after the housing is jettisoned -
[https://youtu.be/su9EVeHqizY?t=239](https://youtu.be/su9EVeHqizY?t=239)

(I was just about to post this question when I decided to just look it up - I
vaguely remember hearing something about this -
[https://en.wikipedia.org/wiki/Elon_Musk%27s_Tesla_Roadster](https://en.wikipedia.org/wiki/Elon_Musk%27s_Tesla_Roadster)
)

~~~
OnlyOneCannolo
Because Elon Musk launched his personal Tesla into space on the Falcon Heavy
test flight.

[https://youtu.be/A0FZIwabctw](https://youtu.be/A0FZIwabctw)
[https://youtu.be/wbSwFU6tY1c](https://youtu.be/wbSwFU6tY1c)

~~~
mannykannot
If only there were a teapot in the trunk...

[https://xkcd.com/1866/](https://xkcd.com/1866/)

~~~
Yizahi
Maybe there was. We can't know now :)

~~~
mannykannot
Indeed, but as Russell himself pointed out, the burden of proof would rest on
anyone claiming it to be so!

------
thatguyagain
Very cool! For someone who knows absolutely nothing about rockets, this makes
it look so much more primitive for some reason. Just these tubes filled with
fuel.

~~~
twicetwice
As others have said, that's basically the case. Most of the complexity,
though, is at the bottom, in the engines. Absolutely incredible machines
designed to withstand—and control—incredible forces. Turbopumps spinning at
tens of thousands of revolutions per second. Insane amounts of heat that need
to be cooled so the engine bell doesn't melt. Handling cryogenic fuels (liquid
oxygen is very, very cold!) at very high pressures, moving them at very high
speeds.

One failure mode, out of the many many possible failure modes, that's
particularly interesting to me is that if the pressure in the pipes going into
the turbopumps (which push the fuel into the combustion chamber fast enough to
keep the explosion going) is too low, then you'll get cavitation on the back
of the turbopump blades, and the forces from that will destroy the turbopump
in under a second. Kaboom.

Oh, also, these pumps have to spin so fast that they themselves are driven by
essentially little mini rocket engines.

For a visual depiction of the complexity of rocket engines, check out SpaceX's
Raptor engine, arguably the most advanced engine being produced right now:
[https://imgix.bustle.com/uploads/image/2020/4/6/c1349369-162...](https://imgix.bustle.com/uploads/image/2020/4/6/c1349369-162d-4430-a789-bad843d8d9ad-
eu0suuexqaizgul.jpeg)

I'm no rocket scientist, though, just an interested amateur. Real rocket
scientists please correct me if I got anything wrong!

~~~
lutorm
_Turbopumps spinning at tens of thousands of revolutions per second._

This is actually not true. These turbopumps are quite large and spin fairly
slowly. The design RPM on the F-1 turbopump appears to have been 5500 RPM, for
example. (That's not to say they aren't complicated, because they were using
55,000 horsepower to push the propellants into the engine.)

~~~
elteto
Not all of them! The Merlin turbopump spins at a whopping 36k RPM!

[0]
[https://en.m.wikipedia.org/wiki/SpaceX_Merlin#Turbopump](https://en.m.wikipedia.org/wiki/SpaceX_Merlin#Turbopump)

~~~
lutorm
36,000 RPM is 600 RPS, which is still aways off from "tens of thousands".

~~~
twicetwice
Oops, you're totally right, I messed that up. Too late to edit the parent
unfortunately. I think it's certainly still impressive, though!

------
205guy
And another TIL from reading the comments on the video:

"Question: Are inertial forces required, and incorporated into the designs of
rockets, in order to keep liquid fuel at the bottom of each tank?"

Reply: "They are in constant acceleration except when staging or after a
shutdown before a re-start. They use ullage motors to accelerate the rocket
just enough to settle the fuel (either small solid rockets or reaction
thrusters) when they are in zero g."

Reply 2: "Apart from Ullage Motors you can also do "Hot Staging" where you
light the next Stage while the current one is still burning. That's why a lot
of Russian Rockets don't have this open Interstage Sections where you can see
the Engines instead of Interstage Fairings."

[https://en.wikipedia.org/wiki/Ullage_motor](https://en.wikipedia.org/wiki/Ullage_motor)

~~~
ashtonkem
Some rockets also pressurize their fuel tanks with Helium for similar reasons
I believe, including the Saturn V.

------
shadowgovt
It's fascinating to observe how little fuel is left in the Falcon Heavy lower
stages when they're jettisoned. That reentry profile really gets to take
advantage of atmospheric drag to sink all that kinetic energy.

------
gorgoiler
This is wonderful.

I’ve never really understood how solid fuel boosters work. Are they filled
with something granular like sand, that empties down the rocket tube?

The video makes it seem as if the entire tube is on fire at the same time.

It’s also fantastic that an asymmetric vehicle like the Space Shuttle was ever
built. What an outlier it seems, amongst the more, I suppose _traditional_
looking rocket designs in this video.

A very poetic leap, as well, to think that the same orbiter that climbs under
so much power is the same vehicle that glides into land without power, all the
way back from orbit!

~~~
PostOnce
This is my all time favorite animation of how a solid rocket works
[https://i.imgur.com/E7J8pxF.mp4](https://i.imgur.com/E7J8pxF.mp4)

so yeah it is all burning at the same time

In the OP's video, it looks like the fire is magically coming out of thin
air... it'd be hard to do the animation style I linked at the distance in OP's
video though, so I'm not sure how they could better animate a solid fuel
rocket

~~~
gorgoiler
Aha! Very nice! So this is why solid fuel boosters are ejected before they’ve
burned out - because they will eventually burn out to the edges of the tube
and the whole thing will start to glow?

------
SergeAx
Solid rocket boosters of Space Shuttle and SLS are quite similar indeed:

[https://en.m.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_B...](https://en.m.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster)

[https://www.northropgrumman.com/space/nasas-artemis-
program/](https://www.northropgrumman.com/space/nasas-artemis-program/)

------
deanCommie
Always a good reminder, what people think about as "rockets" is really mostly
fuel tanks.

I mean intellectually people know that. Rocket = "Engine" \+ "Fuel tank".

But I still think that when people are imagining the awe-inspiring power of a
massive rocket carrying humans into space, they're not dwelling on the fact
that the majority is just a big cavernous vessel for fuel.

------
boublepop
Content like this and the amazing contributing comments here is what I love
most about the internet. When I woke up this morning I did not expect to spend
hours reading and watching videos about space rockets, but here I am all the
merrier for it. Thank you!

------
Nokinside
Saturn 1 (SA-5) Camera Inside Kerosene Tank
[https://www.youtube.com/watch?v=fL-
Oi9m2beA](https://www.youtube.com/watch?v=fL-Oi9m2beA)

------
LordHeini
Time to play Kerbal Space Program again :)

------
apatheticonion
Are reusable rockets more cost effective than disposable (or recoverable by
parachute) solid rockets?

------
unnouinceput
This animation doesn't do enough credit to Saturn V. Tell me again off them 4,
which one carried people to the moon and back?

~~~
NikolaeVarius
None of them. The Saturn 5 was discarded after launch.

~~~
dotancohen
The S-IVB performed the TLI maneuver.

And by any definition, the Saturn V carried the entire stack into orbit. From
orbit you're halfway to anywhere.

