Reference article
Soldier Outfit
The Soldier Outfit combines Soldier Helmet and Soldier Duck into a complete look in 
Duck Life: Space.
Getting the outfit
Buy 
Soldier Helmet and 
Soldier Duck at 
Terra Shop for 50 
Coins each. Equip both pieces on the same duck through duck selection.
Wearing the outfit
The hat covers the head, and the costume covers the body. Wear them together for the full outfit, or mix either piece with other clothing. Clothing does not improve racing skills.