
Astronauts say riding Falcon 9 rocket was different from space shuttle - throwaway888abc
https://spaceflightnow.com/2020/06/12/astronauts-say-riding-falcon-9-rocket-was-totally-different-from-the-space-shuttle/
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DudeInBasement
Who can sum it up with the least amount of words: Liquid smoother ride than
solid rockets

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miguelrochefort
Which one is the Space Shuttle and which one is the Falcon 9?

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catalogia
The Space Shuttle had three liquid fuel rocket engines on the orbiter (pulling
fuel from the big orange tank), but used two huge solid fuel boosters as well.
The Falcon 9 does not use any solid fuel boosters.

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dredmorbius
And for relative thrust, the SSRBs (solid boosters) developed a maximum of
14.7 MN (meganewtons) thrust each, or a total of 29.4 MN. The SSMEs (liquid
fueled RS-25 engines) produced ~1.9 MN thrust each, or 5.7 MN for the three.

Of the 35.1 MN of maximum total shuttle launch thrust, about 84% came from the
solid boosters, only 16% from the somewhat misleadingly named "main" engines.

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

[https://en.wikipedia.org/wiki/RS-25](https://en.wikipedia.org/wiki/RS-25)

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catalogia
Percentage of total maximum thrust is one way to look at it. Another is to
consider that the SRBs get dropped when the shuttle is going about 4,000 km/h,
after which the SSMEs bring the shuttle up to 28,000 km/h.

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artemisyna
This is a nice summary of commentary the astronauts have given since arriving
at the space station, but I wish this article would cite the original events.
=/

Iirc, this is some combination of a the “SpaceX press event” that they did as
well as some words exchanged upon arrival. (I’m not 100% on that, though I do
feel like all the quotes came from videos from their first two days in the
shuttle.)

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userbinator
I wonder if it's more similar to a Soyuz.

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mhandley
The Merlin 1-D Vacuum on the Falcon upper stage is much more powerful than the
RD-0124 used on the Soyuz third stage (934 kN vs 294 kN), but uses a single
huge engine bell, whereas the Soyuz has four smaller engine bells. I would
imagine this might make the Soyuz a bit smoother.

The Falcon also stages really early (this allows you to land the first stage),
so the 2nd stage MVac engine is more powerful than is really ideal. As fuel
burns away, I understand the MVac has to throttle down a lot to keep g-loads
under control. I believe it can throttle down to something like 35%. Rocket
combustion tends to get less stable at lower throttle settings, so this
probably is part of what they're feeling.

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sandworm101
Iirc, Soyuz also hot stages. So no dramatic zero-g cutoffs between stages.

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KuiN
You're right. The first stage (4 conical shaped boosters hanging off the
sides) and the second stage (central core booster) all fire together to lift-
off. When the side-boosters are depleted they jettison (and perform the
Korolev cross) while the second stage keeps firing.

The third stage also starts before the second stage is completely depleted;
this is why there's an "open grate" visible in photos of the rocket (about
half way down the stack, see [1]), gives the exhaust somewhere to go before
the previous stage is jettisoned. Hot staging is advantageous as you don't
need extra ullage motors to deal with propellant being in the wrong place
inside the tanks in microgravity. The Soyuz (and other R-7 variants) are
brilliantly engineered; There's a reason they're still flying nearly 70 years
on.

[1]
[https://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/So...](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Soyuz_TMA-9_launch.jpg/1200px-
Soyuz_TMA-9_launch.jpg)

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Already__Taken
You see a lot of that whole-system level engineering in Russian things imo.

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dilandau
Fuck that's so cool. Imagine being strapped to that thing. Love hearing the
astronauts candid experience.

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ncrmro
I wonder if people will ride the Soyuz one day for that classic vintage
experience.

Seems like such a vital part of our history.

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wiradikusuma
So it's like driving a convertible car with the roof opened? (Of course not
literally)

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jacoblambda
The third-hand description that I've found best describing the single engine
burn is that it is comparable to driving fast on a gravel road.

It's bumpy as hell of a ride due to all the vibration from the engine
placement but otherwise it's not too bad.

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sidcool
What is the difference in weight carrying capacities of the space shuttle vs
Falcon 9?

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dredmorbius
LEO payload mass for the Falcon 9 heavy, fully-expended (no booster recovery)
is 63,800 kg. With booster recovery, 30,000–57,000 kg. For the Space Shuttle
it was 24,400 kg.

The total mass boosted by the shuttle was higher, but much of that was the
orbiter itself, not usable payload.

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mclightning
Are they comparing their Falcon 9 experience to Space Shuttle which flew
almost a decade ago last time?

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sebazzz
And now we wait for Boeing.

