There are people who like roller coasters.
There are people who love roller coasters.
And then, there are people like Will Pemble.
All I need is a little bit of encouragement
to say yes to a crazy idea.
My name is Will Pemble.
I think it got faster.
And I built a roller coaster in my backyard.
Well, of course he did.
I built a roller coaster in my backyard
because once upon a time when my son was 10 years old
Here we go.
We came home from vacation, and he asked me
“Wouldn’t it be great if we had a roller coaster in the yard?”
And it took me five seconds to know for absolute certain that it would be great.
But first, Pemble had to figure out how to build one.
The first time we wanted to build a roller coaster,
there wasn’t a whole lot of information about it.
Okay, I’ll tend to consider it not so bad.
There were a couple of videos online that we could look at.
The companies that built these don’t really like to share their secrets.
So a lot of what we did, we had to kind of learn as we went.
I’m trained a little bit as an engineer. I’m trained a little bit as a carpenter, as a builder,
我受过一些工程师 木匠 建筑工的训练
I’ve learnt how to weld.
I know some stuff,
but really we had to figure this out through trial and error.
And while we were doing that we had to make sure it all stayed perfectly safe the whole way.
The trick to having your roller coaster turned out the way you hoped it will is you do the maths.
You figure out what are the laws of physics that are gonna govern this thing,
and how do I make those calculations and understand what the coasters are gonna do
before you ever put a shovel in the ground,
before you ever bend a piece of steel.
In total, he’s built five coasters.
The first one I built in my backyard, and it was made out PVC and wood,
about a hundred and eighty feet of track.
The second roller coaster I built in my front yard
because there was already a roller coaster in the backyard.
The third roller coaster I built for the Maker Faire in San Francisco,
because I wanted to show my roller coaster to more people
than would fit in my yard.
The fourth roller coaster I built at a friend’s house,
because his kid wanted a roller coaster and we were friends.
And this is the fifth roller coaster, the Goal Boss,
that I tried to improve on everything we had done before.
And I felt like we’ve almost got ourselves there.
The latest is a stomach swirling strench of steel
right out the back door of his northern California home.
A lot of people would put a swimming pool in the yard like this,
just a lot of people, most people would.
I didn’t want that.
I didn’t think that that would be particularly engaging;
I didn’t think my kids would learn a whole lot from that.
And look, I have a roller coaster!
然后 看 我拥有的可是一座过山车！
There are no tickets, no lines,
just strap into the homemade cart, inch up the hill,
and then fly though the turns.
The way the coaster works right now is you get in,
you go on the chain lift.
It takes about 30 or 40 seconds to get from the bottom of the hill to the top of the hill.
So it’s a pretty slow lift hill.
What that does, we could speed it up, but we didn’t.
But what that does is it gives you time to kind of review your choices,
and think about what you’ve done, cuz you look down at the thing,
and it doesn’t look like any roller coaster that you have ever ridden before.
It’s like “Oh my god, who built this thing? Are you sure this is safe?”
By the time you get to the top, you’re just like you’re,
you just you know this was a terrible idea.
And I have the exact same feeling,
so you get that for about 30 seconds.
And then a couple of seconds, you just crest the hill you’re like,
oh, okay. And then just like a nice gentle
and then you do this you just like drop off the edge of the earth into this dive.
And inside of a couple of seconds at the bottom of that first straightaway there,
you’re going 18 miles an hour.
And then you dive into a 70-degree bank turn,
and you go 360, 450 degrees
of 70 degree bank turn back up into the sky.
And then you ride over this trust,
and then drop down into that turn over there, which is right next to the wall.
You go up the next camel hump, which points off the edge of the wall.
And on the other side of that wall
is a 15-foot drop into I don’t know what.
then you turn off of that and then you ride into another bank,
then you roll back to the station.
All of that takes less time than it took me to describe it.
It takes like 17 seconds from the top of the lift hill back to the station.
And it’s utterly horrifying and thrilling,
and the best part of all for me is very very smooth.
But it’s missing something,
at least according to Pemble’s online fans,
who follow this coaster building on his YouTube channel.
This coaster is awesome and a lot of people have seen us online.
And we get a lot of help and encouragement from people
who watch my kooky little videos about it.
One question that keeps coming up over and over again is,
doesn’t it go upside down at any point?
It doesn’t go upside down, yet.
So I’ve had a number of people ask me
if we could add some kind of inversion,
some way to make the roller-coaster go upside down here in the yard.
I have to try.
Now Pemble and his coaster collaborator John Eliot
are making the loop-de-loop dream a reality.
And yes, he insists this is safe.
Before we built this coaster or any of the other coasters,
we started with a spreadsheet.
And we did meter by meter, math and physics
on how the car would behave, how the track would behave,
what the slopes needed to be, what the bank turn would need to be.
All of the things we figured out before we ever started to build any of it.
That’s the only way you can have it turn out predictably.
To absolutely guarantee that things are safe, Pemble turns to his friend Todd.
Okay, Todd isn’t really his friend, he’s a crash-test dummy.
好吧 托德不是一个真人朋友 而是一个碰撞测试仿真人
I know that I weigh 200 pounds and I want to ride my rollercoaster.
So we put our 300-pound crash-test dummy Todd on the roller coaster,
and let him ride it a bunch of times before we ever put a human being on it.
So we test everything.
But an upside down loop is a different thing entirely.
The physics of loops is kind of interesting,
and presents a number of opportunities and challenges.
One of the main things that you think about in loops is centripetal acceleration.
关于环轨 其中一个要考虑的关键是 向心加速度
And that’s the force with which your cart is pushing on the outside of your loops.
So how hard is it pushing against the track?
With a perfectly circular loop,
you need incredible speed, incredible centripetal acceleration,
to keep the car pushing up when it reaches the top of the loop.
Most commercial coasters these days use an upside-down teardrop-shaped loop called clothoid loop.
So the way a clothoid loop looks is
when you enter the loop, you have a nice big radius.
And then the radius decreases decreases decreases decreases very tight turn at the top,
and then back out of the loop.
One of the challenges of our clothoid loop,
will be that we can’t build a really really big one.
We’re gonna need a relatively small radius loop.
The top of our coaster is 20 feet from the bottom of our coaster.
So we basically have 20 feet of altitude,
20 feet of potential energy that we can use to get in and out of the loop.
And when we exit the loop, we still have to finish the whole rest of the course.
So we can’t use up all of our energy just to get through this loop.
If we enter the loop at a certain speed when we run the math on that,
what I’m starting to find is that the G’s
那么作用于小车 乘客 轨道
that you’re gonna pull the force on the cart and the rider and the track and the whole system
is gonna get pretty freaking high when you’re entering that loop.
And by high I mean like 3, 4, 5 G’s, really high.
非常大 大约是重力加速度的3 4 5倍
It’s not going to be fun, it’s not gonna feel good.
It might be something that you’d be proud of having it achieved,
but it’s not going to be something you would enjoy.
After a weekend of cutting, bending, riding and welding,
经过一周的切割 折弯 处理 焊接工作
Pemble and Eliot have a new section of track.
It’s not a loop after all, it’s a barrel roll,
which should fit better into the existing layout.
And according to Pemble won’t subject the rider to painful g-forces.
So what we got here is the very top part of the barrel roll.
So what happens is our car will enter there, there’s entry down there.
But basically the car enters this part of the barrel roll, the rider is pointing this way.
总之就是 当小车进入滚筒这里时 乘客朝向这边
And then they spin around this piece of track,
by the time they finish this top part,
they’ve made a 180 degree roll
from this to that over the course of about 18 feet.
And so we’re feeling very happy about this,
because this was the hardest part to build.
The materials to build this coaster cost a little bit less than $10,000,
it’s the labor that’s gonna get you.
This roller coaster took us about three months me and my friend John worked on it together.
And we probably put about 300 hours of labor into the thing.
So, not a trivial amount of work.
I’ve had a really lucky and wonderful life.
I built one of the biggest web hosting companies in the world,
and I sold that and I made a little bit of money.
I run a management consulting company now called Goal Boss,
we teach leadership and teamwork.
It’s amazing how much of what we learn on the roller coaster project,
figures into the training and consulting what we do.
The new section of barrel roll track is fitted right after the first drop,
it really changes how the coaster rides.
In this roll, the center of gravity of the rider is way down by your waist,
which means that your head whips around,
and there’s just like a whole lot of energy.
It’s not comfortable, its borderline not safe.
Pemble is the only person who has ever ridden it,
and he’ll probably be the last.
It seemed like an incredibly good idea at the time.
Now it’s really cool to watch,
it’s really fun to roll the car over the thing.
I’ve ridden it once and that was plenty.
But if you’re a crash-test dummy like Todd, remember him?
Then it’s a ton of fun to ride.
So my key takeaway from building an inversion into a roller coaster
is if you don’t study engineering and rollercoaster manufacture,
you’re just not gonna get it right the first time.
That’s okay. We’re just gonna do it again.
I think the best thing to do for this coaster
is to tear it down completely and rebuild it,
and design it from day one with an inversion in mind.
My advice to anybody building a backyard roller coaster,
go slow, do the math, be careful
and know when to not ride it.
And don’t forget to have a Todd on hand.
There are people who like roller coasters.