Could an airplane divert all its energy for only vertical speed?

Question

I mean that the aircraft goes only up or down without any (or with at least a minimum of) forward motion. To my knowledge, helicopters (and maybe some military aircrafts) can. Thanks for pilots and airodynamic guys!

Answer 1

I have seen a aerobatics airplane point its nose up and just hover like a helicopter., then it moved up and down.

Most airplanes don't have the power to weight ratio to do this., and have to keep air moving over the wings or they'll fall.

Answer 2

yep, but the thrust to weight ratio will have to be greater than 1:1. Something like a F-15 or F-18 could do it.

Answer 3

The harrier jet can do it by thrust vectoring. It can aim it's jet engines straight down and take off vertically.

Answer 4

If we are speaking of air breathing aircraft, yes but there rapidly comes a point of diminishing returns.  Air has weight and density, a propeller must "bite" the air and the internal combustion engine that spins it lose efficiency as the air becomes less dense or thinner with altitude.  Jets will eventually lose thrust in the combustion chamber as the air becomes less dense.  The rotors or blades on a helicopter are propellers and face the same limitations.  Non air breathing rockets are immune from this limitation.  So, generally an aircraft will eventually stall out in a max climb.

Answer 5

helicopters and jets capable of hovering or verticle take off exert non-verticle forces to stabilize themselves.  I think if you only exert a verticle component  you'd get a rocket?

Rockets don't hover well :)

Answer 6

Ordinary fixed-wing aircraft remain aloft mainly due to lift generated by the wings, and the wings generate lift only when they are moving forward, and that lift is perpendicular to their forward motion.  So ordinary fixed-wing aircraft cannot use all of their energy (I assume you mean kinetic energy or thrust) for vertical movement unless they have enough of it to completely balance or surpass the weight of the aircraft.  An ordinary aircraft can pitch upward and climb for a limited time, using its accumulated kinetic energy, but once that is exhausted (a matter of seconds), it cannot climb further unless it has engines that produce thrust in excess of the aircraft's weight.  Only military aircraft currently are in that category, and even then, only a few military aircraft can do it (and not for extended periods).

A forward-moving wing is much more efficient at keeping an aircraft in the air.  Helicopters manage to move vertically because they have small wings (their rotors) that are constantly "moving forward" and producing lift; even so, they consume a lot more energy than fixed-wing aircraft in keeping aloft.

Answer 7

I once heard that the F-16 can actually accelerate while going straight up.  Amazing.  Any aircraft can swoop up, trading airspeed for altitude.  It won't keep it up for long, though.