Yes, they can - I've seen it. Of course, you have to have a small airplane with a low stalling speed - 30mph or so. The airplane I saw do this was a Luscombe, which took off from the Fremont Airport (now closed) in a very strong wind, and just hung there, about 100 feet above the ground. Notice that it's airspeed was just above stalling speed, but it's ground speed was zero.
Also, when I had my ultralight, which stalled around 7mph, if memory serves, it was fairly common to take off and just climb vertically, because the airspeed was a comfortable 15 mph, but the ground speed was zero.
It's simple: lift has to equal the pull of gravity, or you have to provide vertical thrust. The Harrier jump jets do this, as do several other VTOL designs In a normal aircraft, lift is caused by pressure differentials over an airfoil, typically, the only kind of airplane that can hover in place is one that has a moving airfoil: a helicopter. In the rare event that there is sufficient airflow over the airfoil caused by wind, one can hover in place if lift, drag and other aerodynamic forces are in rough equilibrium. This would require a very light and efficient airfoil with a wide wingspan, such as the Gossamer Albatross, in light wind (11-13 mph).
2 years ago
Last edited at 6:17PM on 3/17/2012
The harrier can, but not for long, also the osprey can, and the F22 (I think it is) can for a little bit. But generally unless you have the right conditions the cannot unless as stated by waldorff above.