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[♪INTRO]
If you've ever taken a science class, you've
probably done some kind of at-home biology,
chemistry, or physics experiment.
And for good reason — a baking soda volcano
is an easy way to get a hands-on look at how
the world works.
Plus you get to make a mess—tons of foam,
red food coloring… your mom is like, “Why?”
But when it comes to understanding space,
at-home experiments are a lot harder.
After all, space is a giant vacuum, which
you can't exactly recreate in your basement.
And even if you could, you shouldn't.
One thing you can build at home, though, is
a rocket.
Specifically, a hybrid rocket engine, which
many engineers want to use to explore the
solar system.
All it takes are some basic household supplies
and a little caution.
All rockets work by throwing something out
the back to propel the rocket forward, and
hybrid rockets are no exception.
Like what we use in current rockets, they're
a type of chemical engine, and the big ones
generate force with a giant, controlled explosion.
We'll do our best to make sure this experiment
doesn't get all explode-y, but we will create
a smaller flame.
And like with a full-sized rocket, we'll
make that fire using two basic components:
fuel and an oxidizer.
The fuel is whatever you're burning to propel
your spacecraft forward, and the oxidizer
helps your fuel catch on fire.
Like the name suggests, this is often an oxygen-containing
compound.
Current rocket engines will sometimes combine
these elements in one solid, pre-mixed block
— that's a solid engine.
Or, they might use liquid engines, which have
separate liquid components that get mixed
as they go.
Hybrid engines are special because they use
a combination of both solid fuel and liquid
or gas oxidizer.
Right now, these engines tend to have less
thrust than the other models, so they haven't
been used on many missions.
A lot of those limitations have to do with
how the fuel burns … which is what you're
about to see for yourself.
So, we don't have a lab or a kitchen in
this room, but we do on SciShow Kids, so I'm
going to go over to the SciShow Kids studio
next door for a little bit of rocket science.
For our hybrid rocket, we're going to use
some cylindrical fuel — this is a pasta
noodle, it's rigatoni, it's got calories
in it.
You burn it to make yourself.
We're going to burn it to make a rocket.
And for our oxidizer, we're going to be
using pure oxygen gas, which will be created
through a reaction between hydrogen peroxide
and active yeast.
The yeast contains a protein called catalase,
which will break down the hydrogen peroxide
into water and pure O2 gas.
Besides the pasta, hydrogen peroxide, and
yeast, you'll also need a few other basic
staples: some safety goggles, a fire extinguisher
just in case, and a lighter or a few matches,
and a small mason jar with a hole knocked
in the lid.
Our jar is about 230 milliliters, or 8 fluid
ounces, and the hole in the top is around
a third of a centimeter across.
The important part is that the noodle should
fit over the hole without covering any of
the hole up, and without any of the hole escaping
from around the noodle.
First, lay out all of your supplies ahead
of time so you're ready to go once the reaction
starts.
Then, you fill your mason jar about three-quarters
of the way with hydrogen peroxide — or about
175 milliliters.
Now, here comes the fun part.
Add a quarter of a teaspoon of yeast to your
jar, and stir.
You should see some bubbles start to form
— that's the pure oxygen.
Quickly place the lid on the jar, and place
the noodle upright over the hole.
Then — get ready for it — light the top
of the noodle on fire!
You should see a small column of flame rise
up over the noodle as it burns.
There is your engine!
That's a pretty good engine!
Oooh!
There, it's going!
Oh my gosh.
Now it isn't producing much force, and any
force it is making is directed into the table.
So the engine won't go anywhere, which is
probably a good thing in this case given that—ah,
large sizable chunk of it is on fire.
The reaction's either going to continue
until the noodle is all burned up, or until
the chemical reaction with the yeast stops.
We're going to have to wait until that gets
a little less hot.
The main limitation with hybrid rocket engines
is that they just aren't very powerful compared
to other rocket types.
And a lot of that is because of how the fuel
burns.
In our demo, the oxidizer flowed through the
rigatoni-fuel, and it's basically the same
process in the real thing.
How fast the fuel burns — and how much thrust
the engine produces — has to do with how
much oxidizer is moving through it.
If the oxidizer has just one hole to flow
through, like with our noodle, it will only
burn a little fuel at a time, so it won't
be very powerful.
The big challenge for engineers is figuring
out how to shape the fuel so there's an
optimal flow — enough so that it can propel
a rocket efficiently, but not so much that
it burns through all the fuel all at once,
which would just be an explosion.
Teams are working on it, though!
There's been more interest in developing
hybrid rockets over the last few years.
And another cool thing about this demo, besides
the column of fire, is that it kind of illustrates
why.
One advantage to this type of engine is that
it's hard to accidentally blow up.
Not that I'm encouraging you to try.
But since the fuel and oxidizer are stored
separately, there's a much lower risk of
accidental explosion compared to a solid engine,
where everything is already blended together.
In these solid mixtures, the block can sometimes
become damaged, which can lead to uneven firing.
And hybrid engines are less complicated than
many liquid engines, since hybrids only have
one fluid component instead of two.
For our rocket, we didn't have to worry
about continuously mixing fluids and hitting
the right ratios and flow rates.
There were fewer moving parts.
In the real world, these benefits translate
to engines that could help us launch rockets
more safely and more cheaply than we are right
now.
We just have to figure out how to give them
some extra thrust.
Unfortunately, that probably isn't a problem
we can solve with pasta and mason jars, so
we'll have to leave it to the experts.
Thanks for watching this episode of SciShow!
If you'd like to keep learning more about
space, we have a channel where we unpack all
kinds of mysteries about our universe — and
the rockets that help us explore it.
You can learn more at youtube.com/scishowspace.
[♪OUTRO]
コツ：単語をクリックしてすぐ意味を調べられます！

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How to Build a Rocket Engine in Your Kitchen (Experiment Episode)

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robert 2018 年 7 月 15 日 に公開

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