How to Build a Backyard Rollercoaster (for less than $500)

[Music] hi everyone have you ever thought about building your own rollercoaster by the end of this video I hope you think about it there are two books that I know of on that very topic and this man wrote both I recently took a trip to Seattle to meet with Paul Greg a retired aerospace engineer who now uses his years of accumulated skill building airplanes and missiles to create meticulously engineered backyard rollercoasters for his grandkids more than that Paul Greg has gone to great lengths to document and refine the process of building his rollercoasters so that if you read his books anyone can build their own so all of your coasters are gravity powered yeah yeah or human powered yeah there's a reason for that you know I I have the capability of designing a chain lift system the trouble is it costs a lot for one thing that's that chain is expensive and the gears are expensive the motor is expensive everything's expensive I didn't spend on the cart and track $450 on this this whole thing four hundred and fifty dollars on this yeah the reason I don't have the the primary reason I don't have a lift system is because that guarantees adult supervision no kid no no little kid is gonna push that up there themselves and I store the carts away from the tracks on teenagers could never get in my yard hurt themselves the construction of these roller coasters is surprisingly simple the materials used our two-by-fours and PVC pipe that you can buy at any hardware store but don't let that fool you serious engineering one into these roller coasters more than I ever guessed just by looking at the finished product I flew to Seattle wanting to ride one of these coasters if I could but before feeling confident enough to do that I had to learn a little more about them from Paul and learn a little about Paul himself I really like these little things you uh you get this for three bucks walking into Paul Greg's workshop there are little engineering kits and toys everywhere which is a sure sign of someone I'm going to get along with in his entryway was a glass case full of Stirling engines boxes of electronics so I made these for their grandkids too the little water jet comes up and this is like a lunar lander it goes up on the water jet and just sits there oh that's really pretty quickly I started to notice the rollercoaster related items in various places around the shop testing equipment and pieces of track the first things Paul showed me were carts he had stored on a shelf so I started out with this this cart is that what I call a two-dimensional cart so the wheels don't articulate it just goes on this track I'm going to show you okay and the kids right in here it's you know it's for little kids this cart as Paul just described is for a two-dimensional roller coaster meaning it might go up and down hills but it doesn't turn side to side this makes the cart very simple because it doesn't need wheels that turn it's literally just a box on for fixed wheels with guides to keep it from slipping off the track that makes a two dimensional roller coaster by far the easiest to build and you can see an example right in Paul's backyard so this is the first track we built Wow we avoided having to make too tall towers by using the terrain in our deck here so this is what you would call it this is like a 2d roller coaster yeah this is the 2d roller coaster it's got a 3d card on it [Applause] that's pretty cool yeah the nice thing about this out and back track is the tracks only 70 feet long but I get it like a 250 foot ride out of it yeah go back and forth it can't go off the top everybody asks me that oh yeah I'm sure you've got the network down on that lays apart Oh does it yeah and there's some there's several reasons why you can't go the tough we'll get more into how Paul puts these tracks together later but for now let's look back at the carts because that I think is the most difficult part to wrap your head around in understanding a full 3d rollercoaster something that I never really thought about is that a cart on a curved track requires wheels that are articulated in all sorts of ways quickly realized that just that 2d cart the 3d cart was going to be much more complex than a 3d carts much more complex than a 2d cart if it has to do a lot of different things it has to do the normal yaw because the tracks turning it has to do pitch because the tracks going up and down and it has to do roll because the track could be turning left or right so you would need to have this on both sets of wheels you may know the back is different yet so there's a problem with this the roll has to get reacted somewhere into the track yeah and I do that all on the because most of the mass is on the back end of the cart this will not react roll because it's free it's got a derp your freedom there what happens when when this happens yeah the front end won't react that the back end has to so that's why this complicated mechanism so react the overturning roll moment right so to simplify a 3d rollercoaster cart means a front axle with all three degrees of freedom to follow a complex track the rear axle needs yaw and pitch but it cannot be allowed to roll or the cart will just fall over you start to appreciate just how much work all is put into this when you realize he's designed 34 different carts in CAD and built six just to solve these various issues with the maximum amount of safety and there's good reason for that thoroughness if I push you hard you might get two and a half or say three g's let's put a 250 pound guy on here that's three pounds times three that's 900 pounds and all of a sudden wow you're dealing or for Jesus if you were gonna do a loop you didn't dieppe trying to get closer to four G's and that's 1,200 pounds so am I gonna put 1,200 pounds on this on this plastic track it all of a sudden you know yeah he realized this stuff needs to be fairly robust now we're starting to see the seriousness of building a homemade roller coaster there's a lot of force applied to this tracking cart the fact that Paul has been able to build these coasters using nothing but two-by-fours and PVC pipe is a testament to how good the engineering is so let's look now at the track so this this is like a little piece of test track that you would have built to to align your wheels and things and build carts on earth well I just store this on here because this one's just hard to do but yeah it's a good idea to look at this track and that's kind of where I started I noticed the ones online when I started had just flat ends here and I thought it would be a big improvement to cut the ends of the ties and they then they just were drilling their screws in there so the side wheels were whacking their screw heads so I the other first thing I did was put these up where the where the main wheels and the side wheels don't hit that the fastener hits these are two of the things left over from my rail tie joint testing so in other words if this rail was square like this I would make a bunch of these and I would put them on here and then I would put my rail on and screw it down that is much stronger than relying just on the wood because now that this plastic is taking the load not that wood breaking apart in a we call a mode 1 when composites go like this that's mode 1 that's a little one failure winters you know and they peel yeah ok this is a steel thing would do the same thing you could make these pretty cheap so this is one of the things Paul and I talked about in detail this joint right here between the rail and the ties this is what Paul determined to be the weakest part of a wooden track so this is where most of this effort has been focused this joint where the two-by-four tie is cupped to fit the rail and slightly offset so there's more support on the bottom of the track is good to about 900 pounds per joint which when you account for the cart having four wheels dividing the force on multiple joints at once that's a pretty good margin of safety at least for the weight of small children at one point Paul worked on designing a coaster to be ridden by full-grown students at MIT and for that he tested other methods of joining the ties some of the designs were actually so strong that the wheels on the testing rig started to fail instead of the joint so that brings us to the next weakest point which are the plastic rails Paul tested these as well to make sure that the pipe between ties was more than strong enough to support the load and it is but there's a problem with plastics and that is sunlight all plastics start out from the factory with nice toughness most plastics and composites you let you put them out in the Sun a while and and they lose a lot of toughness which means they're gonna fracture or something whacks them probably the best thing is and what I recommend to do is people use PVC and I always recommend you use the conduit I did not know this that the conduit style PVC has some kind of UV protection and it's resistant now what that means really sure trying to find data on what that really means like how much more resistant is the gray electrical conduit than the white plumbing PVC I can't find on the Internet I tested it myself though I had tracks painted and unpainted in my yard for two years the fracture toughness loss is about 50% without and it's only maybe 5% with paint the lesson is you probably want to use PVC but yeah you have to paint it the track that I finally am going to ride is the first one that Paul built the 2 D track we saw earlier this actually uses ABS rails instead of PVC which Paul says he's torn about potentially being the better material it's much softer than PVC but it stays flexible and is held up well over time all the same I weigh a lot more than Paul's grandkids so what we'll be doing next is to test the track for a rider of my weight we are certifying the cart and track at the same time uh-huh we're putting one-and-a-half times the maximum expected operating load our next rider is going to be 150 pounds so we need a 225 pounds what's 75 73 and what 74 and a half 75 150 perfect so we're not gonna push it we're just gonna let it go nothing to do for you - yeah just cuz if you push it you don't know what's you don't know what the loads are right Wow I mean that's pretty good I didn't hear anything uh-uh so what we want to do is check every fastener head in the in the high stress spots and see if anything has come loose usually you'd hear something so this track is now certified for a 150 pound rider with a one and a half factor safety awesome that does it for me all right all right so the track held up to a dynamic test of a hundred and fifty percent of my weight so it's safe for me to ride the audio was a little messed up on this next clip because as I rode this coaster my head was tucked in toward the microphone but stick with me because we learned something really interesting here all right let's see okay yeah you your head sticks up higher than a kid that's that exact thing I was showing you on the computer your heads high right your head is accelerating and decelerating a lot different than the wheels did you catch that Paul just answered a question I didn't even know I had about rollercoasters why do they hurt your neck when you're an adult more than when you're a kid the answer is not just because you're getting old and frail it has to do with the distance your head is from the track imagine a roller coaster with a loop in the track this loop is a perfect circle with a radius that is the same distance as your head is from the track this means that when you enter the loop the cart starts traveling around it while your head stays right in the center have you noticed the problem your head was just traveling at the same speed as the cart but in the middle of this loop it's forward velocity drops to zero in physics terms this is called jerk a rapid change in acceleration that on paper wants to happen instantaneously your head also experiences jerk when the cart exits the loop and pulls your head after it like the tail of a whip from zero velocity right back up to its initial speed this model is an exaggeration compared to real life but the lesson is the further your head is from the track the more jerk is experienced as you navigate the geometry of a roller coaster so if you're if you're going down a coaster and you go into a loop where your head stayed in the middle of that loop it would your head with zero velocity zero and then suck the velocity and then suddenly hit the velocity of the cart again up to 25 miles an hour and a very short amount of time and that is that is too much acceleration that would be bad yeah that is probably the most interesting piece of physics that clicked in my mind on this trip it's how a sling throws a stone how a whip breaks the sound barrier it all comes down to how an object is accelerated through a radius my sponsor for this video is brilliant org who specialized in explaining physics math and logic through practical observations just like this I especially like brilliance hands-on approach because of this connection to the real world in a classroom it's easy to forget that a math problem is describing the behavior of real physical objects like a cart on a roller coaster and if you learn that math it can help you actually build one or any number of other things brilliants courses even have storytelling code writing and interactive challenges this active learning is a great way to ensure you really understand the subjects while having fun learning they're a great company I've worked with for a long time check them out at brilliant org forward slash Nighthawk and if you get there fast enough you can get 20% off a premium membership I also want to give a big thank you to Paul Greg for spending the day with me and making this video happen if you want to build your own roller coasters there's no better resource than Paul's books I barely scratched the surface in this video he has modular designs spreadsheets to calculate g-forces and energy loss it's incredible everything he's done to make building a roller coaster feasible in a backyard setting I'll put a link to Paul's YouTube channel and where you can find his books in the video description below thank you for watching this video and sticking around till the end thank you those of you who support me on patreon you're awesome I'll see you next time

Channel: NightHawkInLight

Views: 1,563,986

Keywords: How to build a rollercoaster, how to make a roller coaster, rollercoaster, roller coaster, coaster, how to, DIY, Backyard, Backyard rollercoaster, Backyard roller coaster, Roller coaster loop, Rollercoaster physics, engineering, backyard engineering, awesome, crazy, cool, nighthawkinlight

Id: SsrfBxWYxOQ

Length: 16min 52sec (1012 seconds)

Published: Mon Nov 04 2019