Go to the parking lot near Vapour GT in Destra to get a rocket car. You can find 2 rocket cars here. Moreover, there are six locations from where you can get a helicopter: In Big Freeze City (on a helipad near a building), In Freedom City (near a parking area, middle of the soccer field), in the House park(on a roof), in the Corona City (near the prison), In the D-Town Central (on a helipad).