Steep Spiral

[pilot602]

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"Load factor" isn't the only thing that affects the stall speed.

[/ QUOTE ]It's not? I thought that level flight stall speed increased in a bank =because of= increased load factor.

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But where's the lift vector pointing?

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Why's it matter where it's pointing?? Like MikeD said all that matters is how close you are to CAOA. The lift vector could be pointing towards the earth (like it is during the inverted portion of a 1G roll), you still won't stall. Same idea; you can fly much lower than Vs and not stall, you just have to be doing a push over and flying at less than 1G.

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It matters because now part of your lift is pulling the aircraft sideways instead of supporting its weight. To compensate for the partial "loss" in the vertical lift component your AOA must be increased. Thus more bank = higher stall "speed."

And I completely agree – and know – you can stall at any speed, bank and pitch but the conversation thus far has had folks saying the stall speed won't "increase" (more correctly stated the airspeed read off the ASI at the point the aircraft stalls) because they were flying at a "slow speed" which is not the case.

 

[MidlifeFlyer]

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It matters because now part of your lift is pulling the aircraft sideways instead of supporting its weight. To compensate for the partial "loss" in the vertical lift component your AOA must be increased. Thus more bank = higher stall "speed."

[/ QUOTE ]But lift is less in a descent than in level flight. The question is how much does all this involve? If the net result is an increased AoA, is it significant?

60º bank in a level turn produces 2 Gs. That's because, as you said, you need to maintain the "length" of the vertical vector while adding a horizontal vector. And we know that ultimately, in a steady state climb or descent, the four forces (lift, weight, thrust, drag) net to zero.

But that doesn't mean that lift always equals weight and thrust always equals drag. For example, in a low speed, high power climb (think Vx), thrust is compensating for some of the weight as well as drag. So lift doesn't have to work as hard - lift is actually less than weight.

Something similar happens in a power-off descent. This time drag does the extra work, supporting some of the weight. So, lift is less than in level flight.

Question is, how much? And is it enough to reduce the load on the wings enough to make the bank angle less relevant?

I don't know. Physics is definitely not my strong suit. But go out and do some level steep turns. Once stabilized, raise the nose just a little, you can feel the increased force. Return to level flight. Now relax the back pressure a bit and let the airplane descend - you'll feel the decrease.