I was just reading in the POH a bit when I discovered a few strange points concerning high performance climbs and go-arounds. We all know Vx is 81 knots for the 20. And weren’t we all taught to not normally fly below Vx as this is neither efficient in terms of climb angle nor climb speed (adressed as “behind the power curve”?
Well, why does the POH, on page 4-3 suggest a go-around speed of 75KIAS? I’ve seen the same thing in a manual for a C172M. Then, in the section on short field take-offs, it says “climbs at speeds lower than Vx should be of short duration”. Should there be any? What am I missing, here?
Too further add to the confusion, in the section on balked landings/go-arounds (4-16), the “true Vx” of 81KIAS is used again.
Further down in the POH, in the performance tables for short field take-off distances, they recommend 76KIAS as “obstacle speed”.(BTW, I haven’t seen obstacles move that fast so far…wonder if the FAA knows this term…).
The only explanation I might have is that different flap settings might effect Vx, therefore the different numbers in the book.
CFIs. speak up please!
Maybe though, some of these things have now been corrected as I have these numbers from the copy on Cirrus’ website, which seems ever out-of-date.