As a follow up, the USAF also uses "tube foods" for specialty missions.
According to NATICK. "The purpose of tube food is to feed U2 reconnaissance pilots in the US Air Force during missions that may last as long as 12 hours. The high altitude profile of these missions requires pilots to wear full pressure suits and helmets that cannot be removed, making it impossible for them to consume conventional rations. Tube food attaches directly to a feeding tube that extends through a receptacle on the helmet to the inside where the pilot is able to sip the food from the straw-like tube."
The tubes are simply plastic toothpaste tubes with screw caps, sterilized and filled with the appropriate product. Each tube contains 4.75 - 5.0 oz (135 - 140 g) of ready-to-eat food in paste or puree form and provides between 150 -300 calories. The tubes may be heated if desired. Foods come in three categories:
Entrée: Beef & gravy, Beef stew, Beef stroganoff, Hash browns w/ bacon, Sloppy Joe, Chicken a la king
Fruit: Applesauce, Peaches, Pears, Cinnamon Zapplesauce
Pudding & Dessert: Butterscotch, Toffee, Caramel, Chocolate, Apple pie w/caffeine, Cherry dessert, Chocolate pudding w/caffeine, Peach Melba
Tube foods are also referred to as "high altitude rations" (or, as the pilots say, "food with altitude").
- Food tubes w/attached straw
"I think," said Christopher Robin, "that we ought to eat all our Provisions now, so that we shan't have so much to carry."