Apparently, the Zonai were very busy in The Legend of Zelda: Tears of the Kingdom because they managed to build the Link missiles. Players can attach them to many of the moveable blocks in the game to send them flying into the sky. But how can Link use the rocket to fly up? Fortunately, the answer is very simple.
How to use rockets in Zelda Tears of the Kingdom (TOTK)
In order for Link to use the missiles in Tears of the Kingdom for himself, he must first attach the missile to his shield. Any shield will work for this. Once this is done, players can press the ZL button on the switch to activate the shield and the missile will go up on its own.
However, it is important to note that the rocket will not fly forever. When I was testing it, the rocket exploded after I was about 20 feet in the air. A good measure of its distance is the Zonai ruins that block the way to the Gerudo Desert. If Link uses a rocket there, it will take him to the top of that structure and nothing else. However, this can be improved with stronger Zonai charges.
Where to find rockets in Zelda Tears of the Kingdom (TOTK)
Rockets can be a bit of a rarity in Tears of the Kingdom, but there are a couple of areas that will always have a couple. Near the Popla Foothills Skyview Tower, there is a sky island that has a platform with a pair of rockets (coordinates 0921, -2112, 0558). The same goes for the Eastern Gerudo Sky Archipelago (coordinates -2221, 2382, 1120), which is nice, because players can get fairies there too.
