Frank Uckër wrote:
Again at the risk of a vicious personal attack, I might suggest people here review the coefficient of lift curve. There are two points on the curve where you can produce the same lift - less than and greater than the stalling AOA. Think about what that implies, during stall practice.
I'm not going to attack you, and what you say is factually true, but pretty much impossible to achieve in a normal aircraft unless you have a lot of excess thrust, good low speed control authority, and lightning reflexes.
Yes, there are two points where I can produce the same lift
coefficient pre and post stall. But post stall, I have to have the same airspeed as pre-stall, not something your average trainer is going to be able to achieve.
Next, everything is going to be backwards. Pitching down will increase lift coefficient, pitching up will decrease it. Not very instinctive.
Finally, you've got this thing called longitudinal stability fighting you. Once your lift coefficient starts to decrease, the wing is going to fall and the horizontal stabilizer... loafing along at a low lift coefficient... will keep flying and point the nose down... even if the pilot is trying to prevent it by pulling back unless you've got huge elevator surfaces and perhaps an aft C of G.
As for stalling an airplane on, absolutely you can do it. Three point a taildragger and you've stalled it on... in three point attitude many taildraggers wings are beyond the stalling angle of attack.
Should you stall every plane on? No. Again going back to the lift coefficient curve you talked about earlier, not all are created equal.
If you've got a plane with a large amount of camber in the wing and a very rounded leading edge and low wing loading, the top of the curve will be very rounded. As we approach the stall, we can change the angle of attack quite a bit without appreciably changing the lift coefficient. This is what makes landing those types of planes at low speed a dream, you can ham fist it and the plane doesn't do much. If you finesse it, you can control it very precisely.
In another world are the jets and other high performance aircraft with their high wing loading, non cambered (laminar flow) or inverse cambered (super critical) airfoils, and often pointy leading edges. These have a lift coefficient graph with a sharp peak at the top. You don't want to go anywhere near this one because things happen rapidly when you go past it.
Now back to our 172. If you are around a decent sized field and there are a bunch of 172s or even 182s or 185s around that haven't been modified, take a close look at them. The straight tails all the way to the mid-sixties 172s will have a moderately sharp leading edge. Then go find a later model 172, mid 1970s or later. The leading edges on these are very fat and rounded and actually droop a bit. In fact, minus the wing fences they actually have a poor man's Horton STOL kit installed with the conical camber wingtips.
That is what makes these newer ones much easier to fly, much more stable at lower speeds, and if you shave off a few knots on approach, an absolute dream to land. They don't break very easily at the stall. They don't spin worth crap (also thanks to the larger dorsal fin). Put in some power and they will just mush. At light weights, stall speed goes down, elevator authority does as well, combined perhaps with a bit of miss rigging and maybe a bit of a decent and I could easily see this aircraft not having a clean break stall.
