It is often said in aviation circles that "pitch plus power equals performance".
A. What is it supposed to mean?
B. Is it always true?
C. If it isn't always true, why is it a useful concept nonetheless?
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asked Nov 3, 2020 at 3:18
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$\begingroup$ OK, I didn't downvote yesterday when you made this comment, but I downvoted it today. I did this because sub-part C is asking for opinions, which is grounds for closure, and when I offered an opinion in my answer you rebuked me. $\endgroup$– Michael HallNov 4, 2020 at 19:43
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1$\begingroup$ @MichaelHall-- seems to me that asking for an opinion about why a concept is useful to an aviator is different than offering someone an opinion that they ought not be overthinking or trying to discredit something. But, will delete the "rebuke". Seems you and I are doomed to be forever crosswise. $\endgroup$– quiet flyerNov 4, 2020 at 20:15
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$\begingroup$ and I will remove my downvote when the system allows. I agree too that certain educated opinions have a place here. And to be completely honest, my DV was probably a wee bit retaliatory given my frustration with your comments. However, I don't think the question is useful. It is obvious that you have a tremendous amount of knowledge, but I am not sure what you are trying to accomplish here. It is a very simple colloquial expression, nothing more. It would be like asking what "aviate, navigate, communicate" means, then arguing exceptions to debunk it... $\endgroup$– Michael HallNov 4, 2020 at 20:32
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$\begingroup$ And yeah, we do seem to get crosswise here. I'd love to meet you over a beer sometime, I bet we would clear the air and get along just fine! We do both like to debate things... ;) $\endgroup$– Michael HallNov 4, 2020 at 20:33
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1 Answer
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A. It simply means that the airplane will perform according to the combination of pitch and power control inputs that you make.
B. Yes, why wouldn’t it be? Aircraft are subject to basic laws of physics. These laws are consistent. Every time you pitch nose down and add power you will descend and accelerate. Every time.
C. N/A because it is always true, but it is just a saying. If you find the concept useful to enhance your understanding or explain something, then use it. If not, then don’t. Aviation is full of such sayings to help pilots remember things, like “aviate, navigate, communicate”, “ARROW” etc. Pick the ones you find helpful and don’t overthink or try to discredit the ones that aren’t useful to you.
answered Nov 3, 2020 at 3:49
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1$\begingroup$ "Yes, why wouldn’t it be?"-- I can think of a reason, but will save for later-- $\endgroup$ Nov 3, 2020 at 12:31
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$\begingroup$ Yes, of course you can... (are you thinking region of reverse command?) Still, whatever scenario you detail out you would have gotten there as a result of previous pitch and power inputs. But go ahead. $\endgroup$ Nov 3, 2020 at 15:53
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$\begingroup$ "Yes, why wouldn’t it be?" Pretty sure that the mechanics of supersonic flight are different than those of subsonic flight. $\endgroup$ Nov 4, 2020 at 4:26
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2$\begingroup$ @quiet flyer, neither the saying nor my answer claims that increased pitch attitude results in "more" performance. (whatever that means...) The point is that changing either pitch or power will result in a corresponding change in the aircraft's performance. It will always change, maybe for the better, maybe for the worse. But again, it is just a saying; it isn't intended as an engineering formula. Sub-part C of your question asked for a subjective assessment of the saying's usefulness. I felt that my answer was appropriate to what you were asking. $\endgroup$ Nov 4, 2020 at 19:11
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1$\begingroup$ I would add that the reason that this exists is to remind students that any change in either pitch or power will change performance unless you also change the other to compensate, or that if you do want to change performance, there are two ways to do so. $\endgroup$– StephenSNov 5, 2020 at 4:04