You inherit the spells at each indicated artificer level in the Rocketeer Spells table as artificer spells.
By the time you adopt this specialization, you're deeply familiar with employing its tools. You gain the following benefits:
Crafting. The gold and time required when you take the Crafting task to create an item that grants a flying speed is halved.
Equipment. You gain one set of armor of your choice that you are proficient with, as well as one set of leatherworker's tools and smith's tools.
Infusions. You can use a number of options from your Infusion feature on an armor attuned through your Arcane Propulsion Armor feature equal to your Intelligence modifier, instead of only one. Moreover, you ignore the attunement requirement for these options.
Research. You can take the Crafting activity to create items with a flying speed as part of a rest.
Training. You gain proficiency with the leatherworking kit and smithing kit.
You can take the Magic (Attune) action and attune to an armor you have equipped, regardless if requires attunement or not. While attuned to an armor through this feature, it gains the Propulsion Armor option of your Infusion feature.
The Propulsion Armor feature now grants a flying speed (30 feet) and a hovering speed (5 feet). The flying speed increases by 30 feet as a level 10 (60 feet), 14 (90 feet), and 18 (120 feet) artificer. Moreover, while attuned to an armor equipped through your Propulsion Armor feature and you are using its flying speed, the range of your artificer cantrips are doubled and their damage is replaced with force damage.
Any armor under the effects of one the options of your Infusion feature also has the effects of the Propulsion Armor option.
While you are using the flying speed you gained from your Propulsion Armor feature, you are imbued with the magic missile spell as an artificer spell.