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Those planes work in a little bit different regime. For a plane flying straight up you have (usually) two things happening: 1. It is trading kinetic energy fo

Those planes work in a little bit different regime. For a plane flying straight up you have (usually) two things happening: 1. It is trading kinetic energy for potential energy. 2. They have so much power that their engines can literally lift the entire plane. These planes do not fly. They just use the air to keep the right direction but do not get meaningful lift when going straight up in a straight line.

meheleventyone 5y ago
A wing generates lift in relation to the relative airflow over it, so a plane with some velocity "straight upwards" generates lift exactly equivalent to the lift generated when flying "horizontally" at the same velocity. You can have aircraft with engines powerful enough that they can overcome gravity with thrust alone so can fly upward indefinitely but their wings will still be generating lift, even if they are travelling vertically and it's not useful for overcoming gravity.
- dTal 5y ago
  Through surfaces on the horizontal stabilizer, the pilot controls the angle of attack of the wing, and hence the "lift" force perpendicular to it. If the pilot doesn't want any lift, there's no lift. The "vomit comet" for instance achieves weightlessness by flying a totally ballistic trajectory; the wings produce no lift for up to 30 seconds at a time.
  - meheleventyone 5y ago
    Yes AoA and it's relation to the wing generating lift is just a technical term for "a wing generates lift in relation to the relative airflow over it".
- lmilcin 5y ago
  You are wrong. "Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air." https://www.grc.nasa.gov/www/k-12/airplane/lift1.html#:~:text=Lift%20is%20the%20force%20that,the%20airplane%20through%20the%20air https://www.grc.nasa.gov/www/k-12/airplane/lift1.html#:~:tex.... Since gravitation always points down (BY DEFINITION), "the force that DIRECTLY OPPOSES IT" can only point up. I hope you don't plan to dispute NASA on what is lift.
  - meheleventyone 5y ago
    That's a simple, introductory explanation for kids and that sentence is contradicted twice on that page as well. For example: "Lift acts through the center of pressure of the object and is directed perpendicular to the flow direction." And: "Lift is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid: no motion, no lift. It makes no difference whether the object moves through a static fluid, or the fluid moves past a static solid object. Lift acts perpendicular to the motion. Drag acts in the direction opposed to the motion." So I'm not wrong, even according to the page you cite.
  - FabHK 5y ago
    Lift is defined to be perpendicular to relative wind (and drag parallel to it). What you cite is the simplification that works eg in unaccelerated straight and level flight.

meheleventyone 5y ago

A wing generates lift in relation to the relative airflow over it, so a plane with some velocity "straight upwards" generates lift exactly equivalent to the lift generated when flying "horizontally" at the same velocity. You can have aircraft with engines powerful enough that they can overcome gravity with thrust alone so can fly upward indefinitely but their wings will still be generating lift, even if they are travelling vertically and it's not useful for overcoming gravity.

dTal 5y ago
Through surfaces on the horizontal stabilizer, the pilot controls the angle of attack of the wing, and hence the "lift" force perpendicular to it. If the pilot doesn't want any lift, there's no lift. The "vomit comet" for instance achieves weightlessness by flying a totally ballistic trajectory; the wings produce no lift for up to 30 seconds at a time.
- meheleventyone 5y ago
  Yes AoA and it's relation to the wing generating lift is just a technical term for "a wing generates lift in relation to the relative airflow over it".
lmilcin 5y ago
You are wrong. "Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air." https://www.grc.nasa.gov/www/k-12/airplane/lift1.html#:~:text=Lift%20is%20the%20force%20that,the%20airplane%20through%20the%20air https://www.grc.nasa.gov/www/k-12/airplane/lift1.html#:~:tex.... Since gravitation always points down (BY DEFINITION), "the force that DIRECTLY OPPOSES IT" can only point up. I hope you don't plan to dispute NASA on what is lift.
- meheleventyone 5y ago
  That's a simple, introductory explanation for kids and that sentence is contradicted twice on that page as well. For example: "Lift acts through the center of pressure of the object and is directed perpendicular to the flow direction." And: "Lift is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid: no motion, no lift. It makes no difference whether the object moves through a static fluid, or the fluid moves past a static solid object. Lift acts perpendicular to the motion. Drag acts in the direction opposed to the motion." So I'm not wrong, even according to the page you cite.
- FabHK 5y ago
  Lift is defined to be perpendicular to relative wind (and drag parallel to it). What you cite is the simplification that works eg in unaccelerated straight and level flight.