HSLD

Critical angle of attack and stall speed are related to each other, but they are not dependent on each other. There will be no one-to-one correspondence.

The POH gives stall speeds as a function of weight and flap/gear setting with the airplane in unaccelerated flight and wings level. So lets ignore the variation with flaps and gear. Just consider the flaps up problem on a fixed gear airplane.

You'll notice that the stall speed varies with the weight. The more the airplane weighs (or the higher the g factor) the more lift the airplane must generate to maintain altitude. If you're already flying at the critical angle of attack the only way to get more lift is to go faster. Hence the higher stall speed for the heavier airplane, even though the critical angle stays the same.

So if you're flying around 10 knots above stall speed at 1g you have a little margin relative to the critical angle. You have extra speed and don't want to climb, so you've set the wing at an angle of attack slightly lower than the critical angle. Start turning and you'll add some g's; effectively making the airplane heavier. It won't take much of an increase in g's to eat up your small margin on angle of attack and stall 10 knots above the stall speed for 1g.

If instead you increase speed to 20 knots above stall speed you set the wing at an even lower angle with an even larger margin relative to the critical angle. Now start a turn and you have more margin to eat up before you get to the critical angle and stall 20 knots above stall speed.

And so on. The faster you go the less angle of attack you need and the greater your margin relative to the critical angle. The faster you go the more g's you can manage before you eat up all your margin.

Now, for Va.

The airplane is designed so that if you are at Va you will be able to pull enough g's to just get up to the maximum maneuvering design load (g factor) of the aircraft. Then you exceed the critical angle of attack and stall. If you go slower than Va you can't get to the design maneuvering g factor before you stall. If you go faster than Va you can pull more g's than the aircraft was designed to carry and overload the structure. So if you're going faster than Va you're supposed to avoid full/abrupt control displacement in order to avoid overloading the structure.

Back to speed.

You stall only if you exceed the critical angle of attack. Stall speed is just the speed you happen to be at when you stall. The speed is related to the critical angle by a complex relationship between many variables - weight, bank/yaw angle, c.g., air density, and probably a couple more things I can't think of just now. But if you stay at or below Va you won't overload the structure.

So critical angle of attack and stall speed and Va are all related, but different concepts.

If you can manage to go straight up at Mach 1 and force the angle of attack far enough you can exceed the critical angle and stall. If you can manage to go straight down at a very slow speed and force the angle of attack high enough you can exceed the critical angle and stall. Force the angle to far and you stall - upside down, right side up, on your side; fast, slow, doesn't matter.

Concept 1: Stall happens when you exceed the critical angle.

Concept 2: Stall speed is the speed you're at when you exceed the critical angle. It depends on a lot of things. But the speed doesn't make the airplane exceed the critical angle.

Concept 3: If you're flying at or below Va (in the specified configuration for that maneuvering speed - flaps up at a specific weight for instance) you'll stall before can damage the airplane.

I like to try to explain these kinds of things, but I'm not sure I do it very well. Hope I helped at least a little.

Study your ground school course hard and don't fall behind in your studies. Fly a bit less often if necessary to keep up with the book. You don't want to be out there not knowing what you're supposed to be learning. Learn first; fly with knowledge. It beats a lot of the other possibilities.