I didn’t know about the Tiger Moth, though I did know about the 109. Didn’t the Globe (Temco) Swift have slats?
On airliners, do the slats have gap between them and the wing? I know that the aircraft mentioned have slots with the slats; but I didn’t know if this is the case on heavies, or if they just ‘drooped’.
Pretty sure the Swift, like Stinsons, had LE slots (non-moving), not flaps. Those delayed stall but did not move CP.
Slats are essentially slots that can be retracted, i.e., the purpose of the slat is to create a slot, so yes airliners with slats also have a slot between the slat and the main wing.
Hopefully your pilot is a happy camper, but… not likely: Secrets pilots won't tell you - CNN.com
First you’d need to clearly define terms like “intensity” and even “vorticies.” I don’t think that winglets have any effect on the vorticity. They only spread it out, so it forms a cylinder rather than a thin line, and that reduces the air velocity in the center of the rotating pattern, which reduces the KE. More vorticity is emitted by the wing’s trailing edge. It’s a misconception that the wingtips are “the” source of vorticity.
The wake produced by aircraft wings is a kind of well-organized turbulence which moves downward. Imagine propelling yourself upward by flinging jars full of water downward. You can’t avoid the work in flinging the jars. But you’d do less work if the water in the center of the jar wasn’t spinning.
It’s easy to get mired in the details. Here’s a thought experiment to clear up confusion.
Induced drag isn’t exactly drag, instead it’s extra work performed by the engines. Imagine a hovering rocket, or better, a hovering helicopter. In both cases, work is done in throwing down a narrow parallel “exhaust plume.” You cannot avoid doing this work. But you can reduce it by throwing down a large mass slowly, rather than throwing down a small mass quickly. (A rocket engine with an extremely wide engine-bell will perform less work while hovering. A helicopter with extremely wide rotor diameter, same thing. And a rocket with an infinitely-wide engine bell can create propulsion without having to do any work at all. Beware of taking infinitely-wide wings seriously, or they’ll screw up your understanding of reaction motors.)
The upward lift force produced by a hovering rocket or helicopter in both cases is created in reaction to the downward acceleration of gas. F=mA. Accelerate gas downward to a constant velocity, and that will balance the aircraft weight. Minor issue: the rocket carries its exhaust mass on board, while the helicopter draws in that mass from all directions. But both crafts are creating a downward plume, so both are getting rid of their downward gravitational momentum by dumping it into that plume.
OK, now give a big sideways shove to your hovering rocket or hovering helicopter. It drifts rapidly sideways until eventually halted by viscous drag. While it’s moving sideways, it essentially becomes an airplane. It produces the vortex-wake of an airplane: the down-flowing pattern with two counter-rotating regions. But it’s still much like the non-drifting rocket: it’s supported upon a downwards-flowing plume of mass-bearing “exhaust gases.”
The confusing part of the picture is that, if the helicopter was moving fast sideways, while its plume of “exhaust gas” was moving downward more slowly, then the plume is spread out into a very wide diagonal pattern. It’s so wide that we might miss its downward tilt. We might mistake it for a horizontal wake of spinning air.
So one method of understanding flight is to mentally halt the sideways drift of the airplane wing, yet still retain the flow pattern which creates the upward force and the hovering action. Or in other words, squeeze the diagonal pattern of downwash in sideways so it becomes a vertical plume. Then we see that the wing is drawing in air from all directions (like a contracting sphere of onion-layers.) The inward flowing air is continuously ejected downward as a parallel plume. The wing’s downward force upon the air causes a major mometum change in the air passing by, and this momentum is the difference between a wide contracting sphere of air flow, versus a narrow downward jet of air flow. (It’s Feynman’s lawn sprinkler, where “blowing” gives a big reaction force, but “sucking” does not!)
Obviously we can’t get rid of the down-flowing gas plume below the hovering rocket or helicopter. All we can do is try to make the edges spin as little as possible. Stop the turbulence without stopping the downward motion.
Once you have the “hovering helicopter” air-flow pattern in your head, all the details of the air-flows around a sideways-moving wing can start making sense.
But be very careful to avoid thinking in terms of 2D airfoil diagrams. In two dimensions, no diagonal exhaust plume arises. In 2D, an airfoil is flying by venturi effect with distant ground, and not flying by creating any downward ‘exhaust plume.’
If you just want to get a grasp on the physics of flight you don’t need to actually be on the plane, an R/C plane should be enough for you to learn how each element of an airplane contributes to flight and control. In fact if you are really curious it allows you to do things few would dare to do on a piloted plane, and I’m not talking about some crazy air maneuverer but actually modifying the airplane to see how a change affects it’s flight performance. From just changing the center of gravity, to increasing the surface area of the controls, changing dihedral, etc, etc. Fun times!
It would also save you a bundle…
That’s why the runway is so long. An aircraft of X configuration and Y total take-off weight (aircraft plus fuel plus cargo plus people) needs Z distance to accelerate to speeds V[sub]R[/sub] – the speed at which it is safe to bring the nose up – and V[sub]2[/sub] – the speed at which the airplane has sufficient lift to take off.
Once in a while this doesn’t work out. Runways have a safety area in case the pilot needs to abort the take-off, but the plane won’t decelerate soon enough to stay on the runway.
FAA and ICAO are extremely concerned with safe operations of aircraft. Pilots go through lots of training for smooth departure and arrival operations, and aircraft are designed and tested for the same reasons.
Flying is safe and fun. Getting there – well, that’s not a GQ thread.
