Hello everybody,
I'm Robin. I live in the netherlands and i've read for 5 years on this forum, i really enjoyed al the beautiful coasters you all make! But now i want to show you someting i maked last year.
I built a lot with knex in my early years, now I'm mainly concerned with building fairground rides in scale 1:25, i've got a kmg inversion, booster and huss take off ( Click here to see a picture of this models. ). But last year i like to make something from knex again.
I'm third-year student mechatronics, and i want to combine the things i learn at school with the knex coaster, i came out on a vekoma boomerang because it got a lot of technics to control.
Ow yeah.. My English is not very good, i hope you can understand it. I think sscoasters is a good way to increase my English level.
This is the first picture i maked of it, i shot this picture on 4 Juni 2012, the start of the building was a few days ago. I used the tube supports for the first time on this rollercoaster.
The highest point is 1,7 meter (5,57 feet). But later i increased the top to 1,8 meter (5,91 feet), the train hasn't enough speed to complete the track.
The base for the looping.
Looping himself.
Then i didn't work on the coaster for a few months, but in the and of 2012 i start building again. This was a try out of the cobra roll.
That looks better.
I didn't had enough middle cars to make an 7 cars train, so i bought an new screamin serpent.
7 cars!
Because my camera broke down i didn't take pictures for a while, the following pictures are from a later stadium. The supports are finished and i placed an frame under the track. This was needed because i had to move the rollercoaster to an exhibition of rides in an small park in the Netherlands (called Drouwenerzand, i've organized this exhibition with two friends.).
The track and supports are complete, now comes the technical side of building this rollercoaster. I tried to make a brake system who brakes from the side, but it didn't works good enough. Then i designed an real rollercoaster brake system.
I didn't want to modify the cars (drilling, gluing, cutting and things like that), so i make a system whats mounted under the original screws. If i want i can remove this fins very easy.
This is the brake system who i placed in the station.
3 of them must be enough.
This is the system to open and close the brakes.
You can see a small motor left in the box, this motor opened the brakes. Rubber bands supply the power to press the brakes against each other.
Then i started with the system of the first lifthill, i maked an catch car from wheelsets of an screamin serpent car. I placed 3 little magnets on it, the last car of the train also got 3 magnets. The magnets connect when they are close to each other. On the bottom of the lift is an pulley who lift the catch car up (the pulley is placed at the point of the hydrolic motor on the real vekoma boomerang).
On the top of the lifthill is an small construction, the catch car fits under it, but the train not. So the magnets disconnect from each other.
The second lift was a lot more complicated, the real boomerang used an chain lift. When the train is on the top of te lift, the chain drops down and the hook under the train has nothing more to hold.
(You can see it in this movie at 0:32 Speed of Sound testrun (testrit) Walibi Holland - YouTube )
This wasn't possible with knex, so i had to make an another system. This one is inspired at the catch car from an giant inverted boomerang. This system catches the brake fins under the train (the real one catches the second brake fin I thought, but my rollercoaster catches the first one).
Here you see the catch car under the second car, the front coach didn't has an brake fin.
This was the first system i maked to lift the catch car, but it didn't works really good. The wheels (aandrijfsysteem) worn very fast and hasn't enough power to lift the train.
Then i designed this system with two pulleys. They are powered by the same motor. The rope on the pulley rolls over each other and hereby the rope is no longer tight. To prevent that i placed a rope tensioner.
As last i must create a control system, i used the siemens logo plc (programmable logic controller) with an additional module. I needed 6 sensors to detect the position of the train and the position of the catch cars.
The sensors are 'inputs' for the plc, the buttons to control the ride are also inputs. In total i needed 8 inputs.
Inputs plc
Sensor 1: Train is in the good station position.
Sensor 2: Catch car lift one is down.
Sensor 3: Catch car lift een is up.
Sensor 4: Catch car lift twee is down.
Sensor 5: Catch car lift twee is up.
Sensor 6: Train approaches lift 2.
Knop 1: Start button.
Knop 2: Reset button.
Here you see sensor 6, train approaches lift 2. This sensor is called an reed contact, he makes the circuit when a magnet is near. On the train you see the little magnet.
I had 5 thing to control.
Motor lift 1
Motor lift 2
Motor for brakes
Lamp on the start button
Fault lamp
These were controlled with 8 outputs.
Ouputs plc
1: Lift 1 up
2: Lift 2 down
3: Lift 2 up
4: Lift 2 down
5: Brakes open
6: Brakes closed
7: Lamp startbutton
8: Fault lamp
Then i programmed the plc, it takes me 2 days to make and test the program.
This are the relays to switching the motors.
This is the plc. The wires on the top are the inputs, the wires on the bottom are the outputs.
There are only 2 days left for the exhibition at Drouwenerzand, i built this simple station.
And after a long way, the boomerang is placed at the exhibition! Some parts of the track are not 100% smooth after moving the rollercoaster (Pictures are made by Mirella Salvetti)
(Pictures made by me)
This is how the ride looks now (picture is 7 months old, but it's still in the same position 
)
And an video of the ride in work.
I maked some video's of the boomerang at Drouwenerzand, i still had to upload these.
Thanks for reading! I hope you enjoyed it (and understand it... 
)
Edited by RobinRide, 05 October 2022 - 01:18 PM.
This is incredible!
