I'm currently building an amusement park in Minecraft (1.12), with roller coasters. Now I want to build a Multi Launched Coaster, that means I need a rocket launch. How is that?
Do you play with mods?
The fastest booster seemed to be next to a block, bouncing off of it and driving away quickly
If you want to send several at once do it with repeaters and several starts.
I play without mods. I was just asking because I saw such a booster in a video of 'TheJoCraft'.
Look at YT
There he presented a rollercoaster, I do not know its construction.
That's why I say yes, look for yt after minecart tutorials