I just noticed that the design of the propeller has some problems; it needs a stronger fire to launch the rocket.
The holy fire the plateau giants guard is extremely powerful.
Please get the blue holy fire in the altar on top of the Great Axe Lair. Watch out for the giant chief, Waltawa, who watches over it.
You may need to enlist help. If you don't defeat Waltawa, you'll never get the fire, and you can kiss your Space Camp-fueled astronaut dreams goodbye.