flaps

The PA-28 has a lot more switches than the Tiger Moth, but any fool can turn a switch on and off. There's one extra control that's taking me a bit longer to get used to.

On the floor to my right is something that looks and works like a car's handbrake lever, just a little longer. By pressing the button with my thumb, I release it from its position on the floor of the cockpit and I can pull it up to a detent. This lowers the flaps. According to my textbook, this makes the airplane want to pitch up, and you have to push the yoke forward to counteract, but in reality that's barely noticeable. The real reason to push the yoke forward is that the flap generates some extra lift. If I was flying level before, with the horizon dead in front of me (it lines up nicely with the compass), then after lowering the flaps, I need my nose lower to stay level: the horizon will be above the compass.
That hardly seems worth it, but there's more. If I press the button on my 'handbrake' lever and pull it up to the next notch, the flaps go down further. This time, the tendency to pitch up is more noticeable, and I have to really push the nose down to stop the aircraft climbing. A tendency to slow down is also apparent: that extra lift isn't free, and the cost is increased drag. By lowering my nose I can still fly level, but if I want to keep the same airspeed, I'll need to add power.
Then, I can 'apply the handbrake' one more time and get the third and final stage of flap. I really need to stop the aircraft pulling up this time, and despite the extra lift I have to choose between losing height or losing speed. The handbrake is now sticking out of the cockpit floor at 45 to 50 degrees. I could almost hang my hat on it, but instead, I want to 'release the handbrake', like you might in a car, but in stages, gradually reducing the flap until it's all the way up: what they call the clean configuration.
So really, when I learn to fly this aircraft, it's like learning four different aircraft. The amount of flap determines the lift-drag coefficient of the wing, which in turn changes what "straight and level" looks like, with the horizon at different heights up the windscreen. It also changes the stall speed of the aircraft: the extra lift with flaps down reduces the stall speed considerably.
This might all seem like a lot of extra complication for the privilege of getting a different view from the cockpit, so what's it all for? To land. By increasing drag at the start of my approach, I get to descend and reduce speed at the same time, so I can make a slower landing: that's safer and uses less runway. The nose-down attitude with flap lets me see more of the runway, so I know where I'm aiming for.
The engineering improvements in flaps between the 1940's and 1970's allowed light aircraft - that's most of the GA aircraft operating today - to run more efficiently at higher cruising speeds without needing much faster landing speeds. And if you've ever looked at the wing of an airliner during an approach and landing, and noticed the various extra surfaces—flaps, slats, and spoilers—deploying like some kind of Transformer, then you've seen the reason today's large aircraft can cruise efficiently at 300 knots without needing a runway longer than the city you're flying into.

Learning the attitudes for the three stages of flap is definitely an extra challenge on top of the clean configuration, and I need to keep practising to get it right.