*click*
Dear Epic Games,
Hi! It's a me, Austin!
I know this is a totally hipster thing to say,
but I've actually been playing Fortnite on and off since before it was popular, and I am terrible at it.
I am just the worst. That's not really relevant to this video at all,
but I just.. I just.. I thought that you should know how atrocious I am at this game.
I'm an introvert! I panic! I don't like social interaction,
so I drop down at the very edges of the map and spend the entire match
hiding from people and inching my way toward the center
getting progressively more anxious until someone finally gets the jump on me and my character
dies from a heart attack!
(Song plays)
(What point was I trying to make?)
Right! Before it was popular. Why do I bring that up? Because for almost an entire year,
I've been trying to brainstorm a video idea for this game.
Is the world population screw because 98% of humans were wiped out?
Nope!
Turns out we'd be just fine other than being more or less rewound back to cave-person days.
Viable human populations can number in the tens and harbors enough genetic diversity to avoid major genetic illnesses,
Although family trees would be a bit Redneck Rampage-y. Okay, so a rocket creating space-time rifts.
Ehhh, that wouldn't happen.
Alright the cube.
The CUUBEE!
Let's do something about THE CUBE!!!
It's a bouncy... jello... brick.
I got nothing. And then I realized, after all that, the answer have been staring me in the face all along.
It's been there since the very beginning. It's not a plot related thing.
It's not something you wonder about,
but it's something that every single person who's played fortnight or watched a streamer play fortnight is familiar with.
The battle bus.
HOW the HELL does this thing work?
I can say with 100% conviction that this was absolutely one of the most fun episodes I've worked on in a long time!
Time the math was a joy, and even the problems I ran into by... *chuckle*
Accidentally tacking on an entire extra number to my air pressure calculations
that gave my atmosphere a density more resembling Aerogel, than actually air.
Buoyancy mathematics is just fun, and easy to understand and explain in a way,
that's a typical aerodynamics isn't.
Alright! So BUUOYANCY.
How does it work? And can we use it to lift a Grade A big ol' honkin' battle bus into the sky!
The answer may surprise you!
Buoyancy is everywhere you have it fact, right now,
sitting in your chair watching this video in class, or on the toilet
Buoyancy is an upward force exerted on any object, like you that is immersed in any fluid.
Not liquid mind you.
FLUID!
There are a lot of complicated and technical definitions for fluids and science and physics.
But the TLDR; a fluid is any collection of molecules that deforms easily to stresses.
So... gases, plasma, liquids.
These are all fluids.
And any object that submerged in a fluid deforms it, and that fluid pushes back.
An object just sitting on the table has therefore several forces acting upon it.
There's the force of gravity pulling it down, the force of the surface pushing up,
and the force of these surrounding gases that are deformed by the object pushing it from all sides.
The sides forces cancel out, and what you're left with is a single upward force exerted by the fluids.
This! is BUOYANCY.
The amount of upward force created is dependent upon the mass of the displaced fluid.
This is why a ship like the Titanic could float in water, but not in air.
Water has a significantly higher density than air.
And this is why it's sank when it filled with water.
It was no longer displacing enough fluid to stay floating.
Hot-Air balloon like the battle bus take advantage of this principle by heating up the air inside the envelope.
That's the technical term for the balloon.
This reduces the mass inside the balloon while increasing its volume.
As gases heat up, they expand.
So as the battle bus inflates its balloon with heat, some of the air escapes from the bottom
as it's pushed out by the decreased real estate for violently flailing molecules.
The balloon will also increase in size as the heated up gas pushes outward, displacing more of the fluid
This increases the buoyancy force and decrease the total mass of the system, which can allow it to float.
Simple, right?
So in order to know if this battle bus can even work, we have to take a few measurements.
This thing is almost a component for component remake of the American blue bird vision model of bus.
Which weighs in at a whopping 14,969 kg or over 33,000 lbs!
YIKES
However, if you were wanting to make a battle bus in real life, you'd be smart,
and got absolutely everything you could out of the bus.
We can even see by peeking in from the waiting zone that there don't appear to be any seats inside.
This is a good start, since a standard floor plan of a blue bird vision has over 40 seats,
with each weighing a conservative 10 lbs.
We can actually dump almost 200 kilograms of weight just out the gate.
Now we can see from both the starting zone and the crash battle bus on the island that the engine is still in the bus.
Which would probably be a Ford 6.8 l Triton v10
capable of pushing a respectable 362 HP or 620 Newton meters of torque at 3250 RPM,
with a maximum rpm of over 5,000 and a nine point two to one compression ratio...
*Evil laughter*
*Barking*
Which would weigh over 283 kg or 600 lbs
This probably means that the transmission as 6R 144 torque shift at 147 kg
and the cooling systems and the alternator are all still inside.
And you can see from the crashed bus that the drivetrain,
this long piece here that's responsible for distributing power from the transmission to not just the front wheel,
but also to the back ones is still in place.
What does this matter?
WEIGHT!
SO
SO MUCH
SO MUCH WEIGHT!
If you wanted to build a battle bus in real life, you would just...
remove all of this.
Cut this thing: transmission, alternator, engine, drivetrain, radiator, electrical system,
EVERYTHING MUST GO!
SUNDAY!!!
SUNDAY!!! SUNDAY!!!
SUNDAY!!! SUNDAY!!! SUNDAY!!!
*static*
If we remove, ALLLLLLLLLLL the stuff we don't need, we can bring the weight down from 14,696 kg to 13,903 kg.
That may seem like a small gain, that's over a metric ton of weight.
That's over 21,000 hotdogs of weight.
Zell would lose his FREAKING MIND!
Now wait, before you celebrate this victory of human engineering,
you can't forget why we did this... To pack this thing to the gills with people.
At first I was convinced that this would be the most difficult part since there's
100 freaking people crammed under this thing at the start of any given match.
But the fact of the matter is that these busses were rated to house 78 passengers IN SEATS
So cramming 22 more folk when it's standing room only isn't that much of a stretch.
The problem arises when we factor in how much these people weigh.
A hundred people weighing...
Let's be generous and say 60 kilograms, since this is a post-apocalypse after all,
would add over 6,000 kg of mass to this thing.
*Chuckles* Yikes
Glad we took all the weight out aren't ya???
This give us a total mass we need to lift over 19,903 kg (19.903 Metric Tonnes)
over 43,000 lbs or 207,323 cans of Fancy Feast gravy lovers beef fest in roasted beef flavor gravy
#NotASponser
Now doing some clever pixel measurements, we can figure out how much Buoyancy forces the balloon is causing
if we can figure out its size.
Using some approximations that are overly generous we can calculate that it has at most,
an internal volume of just shy of 250 m^3 of air.
And we want to heat this up as much as possible to minimize its mass, so the balloon is lifting less weight.
If we blast this air until to a piping hot 225 °C,
JUST shy of the melting point of nylon,
one of the best materials to make hot-air balloons out of, we can cut the internal air density at sea level
from 1.225 kg/m^3 and 305 kg to .71 kg/m^3 or just 176.4 kg.
Now we're talking!
Now we could reduce the weight even further by using helium, but it'd be hard to heat and contain
as the gas would likely just escape out the hole in the bottom.
And hydrogen...
Well, we've done hydrogen before. (Flammable)
Taking all this into account, we have a lifting force of over 2,991 N
AWESOME!
That is a LOT!
It's got the word 'thousand' in it.
Unfortunately...
It's garbage, total trash.
It's enough to lift, probably like one person off the ground in a wicker basket.
But nothing close to enough to lift this bus packed with people plus the air inside the envelope.
Even if we magically sucked all the air out of this thing, it would barely increase the buoyancy.
And not nearly enough to lift a hundred people in a freaking bus.
Maybe if you put Rockets on the bottom of the bus you could do it.
But even still, this freaking thing barely puts a dent in the 196,899.8 N of force needed to lift this thing up in the air.
I know what you're thinking, "But Austin gravity! Gravity and fortnight is probably lower than the Earth's. it's a video game
"But Austin gravity! Gravity in Fortnight is probably lower than the Earth's.
It's a video game. Look how high you can jump man!"
Oh, you do not want to deal with me on this one Kimosabii, because
YOU'LL GET REKT!
Gravity in almost every game out there is way higher than Earth's.
People just have awesome gluts that can jump super high.
That's because platforming at 9.806 m/s² just creates a LABORIOUS game feel.
And fortnight is no different. Using the upturn bus as a ruler with a width of 2.438m,
we can measure the gravity of fortnight, which clocks in at over 28.09 m/s²,
or over two point eight times the surface gravity of Earth
So... no.
doing all the math- *voicecrack*
*coughing*
So, no. Doing our math using Earth's gravity is more being generous.
But we're not done yet, not by a long shot.
So, fine. This doesn't work. Well, what would it take to lift this behemoth off the ground.
To cancel out all the 196,899.8 N of force needed to lift the bus,
the air in the balloon and the people inside?
A balloon would have to be 16,526% larger than the one we see in game.
Which, you know, it's freaking giant!
It'll be 37 m across, almost twenty times larger than modern hot air balloons.
Holy crap!
That's large enough to hold 46,669,846 big gulps from Seven-Eleven!
At the current camera zoom in to take a 4k monitor
tilted 90 degrees on its side in order to show this thing on screen.
*lol*
*breathe in :O*
And then of course...
There's the air pressure at altitude, which decreases the efficiency of hot-air balloons
as the difference in pressure between the inside and the outside diminishes exponentially with each meter you float up.
Using the falling speed of the hang glider,
measured again with the width from the overturned bus,
which turns out to be 3.18 m/s or 7.11 mph,
we can figure out how high this bus is at start.
And... with a fall time of over 2 minutes 44 seconds and three frames to sea level,
we can determine that this bus is floating over 520 m above sea level.
Where the surrounding air has a density of 1.15 kg/m^3
and the density inside our oven in the shape of hot-air balloon is .6659 kg/m^3 .
And turns out at 37 meters wide.
Our balloon is almost perfect!
In fact, it'd actually be able to float a little higher before reaches equilibrium.
So we could probably drop the temperature inside down a schosh and reduce the risk of accidentally melting our balloon!
Honestly, I'm impressed!
Most things are completely improbable and unfeasible.
But this mostly comes down to a problem with scale and aesthetics.
DUH!
Turns out sometimes things that appears mostly stupid are actually mostly... not stupid.
Well done Epic Games!
You made a mostly possible thing.
CONGRATULATIONS! (hurray!)
Although I would respect you infinitely more
if you actually made your battle bus look more like this... (KSP lol)
instead of this...
sincerely, Austin.
Since he made it here to the end plate, why don't you subscribe to the game theorists? (don't forget to ring the bell!)
I D E M A N D Y O U D O I T ! ! !
*Dramatic Music Start*
*DUM DUM DUMMMMM!!!*