# Angle of Attack to Vertical Speed (Edit)

i misspoke. I now know what I was trying to describe. Every instance of “AoA” you can replace with “pitch” lol

I’m finding it a tad difficult to articulate exactly what I’m asking, but here it goes (i’ll ask it in different ways lol):

How can I predict my initial vertical speed/climb rate upon take off? How can I get this relation: angle of attack (AoA) → vertical speed (V/S)? Are there tables for airliners regarding this relation?

I am aware of the plethora of factors pertinent to this relationship, such as: temperature, air density, weight, flap setting, (indicated) lateral airspeed, %N1, etc…

I would to predict this AoA → V/S to a good degree of accuracy for the sake of my own flight path calculations; that is, to set waypoints to various altitudes so my climb-autopilot (from a third party app) can follow a normal, realistic flight path on the way to cruising altitude.

my main limiting factor to this as of now is I simply cannot predict my initial climb rate with any practical degree of accuracy.

For example, I don’t know how my 70% load Boeing 737-800 will climb with a rotation speed of 137 kts IAS, AoA of 15 deg, FLP 5, 90%N1, on a given summer day.
is there some sort of formula/table to relate these values to get the AoA → V/S relationship?

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There is no such “conversion table” between AoA and VS to my knowledge. You can get positive VS with negative AoA (c) and negative VS with positive AoA (b).

(Feel free to correct me if wrong)

Picture from my flight theory textbook

AoA ≠ pitch angle, that’s for sure. Just tested in your given condition, the AoA should be around 5 degrees. 15 degrees AoA will stall the plane.

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VS isn’t something specific that you aim for.

You fly for specific airspeeds and adjust your pitch as necessary, and end up with whatever random VS is created by the combo of airspeed, altitude, pitch, wind, etc

If you do notice that your VS is ridiculously high, you adjust your power to bring it back to “normal” (not usually a specific number).

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If anything, you might find pitch angles related to a stable climb rate (which depends on air density, power setting and weight). The AoA is “baked into” the pitch that gives you each climb performance entry in such a table.

But though pitch does imply a particular AoA at work in a stable climb, as @FlightGT points out, in general AoA doesn’t relate directly to VS:

AoA is the angle the relative wind is hitting your wings, and is related directly to how much lift you’re generating.

How much the force of lift helps or hurts your VS also depends on how your aircraft is oriented: a fighter jet in a vertical climb has an AoA that doesn’t help at all with VS.

In a stable climb you have no acceleration in any direction, so you have zero net force in all directions. The force that AoA is producing in a climb exactly cancels out the force of gravity, for you to have a constant VS. (Though when you entered the climb you did produce a net force up that accelerated you from zero VS, up to your stable positive value for VS).

As @SWAviator implied, you don’t usually directly chase VS (even though there is an exact “settling value” of VS that corresponds to each particular setting for power, pitch, weight, and air density).

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Except in straight and level flight, when they are equal.

Such a high AoA means either: too heavy, too high, too slow, pitched up too fast, or some combination of these.

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When you are pulling into a climb, angle of attack will initially increase, however, as the vertical speed builds, the angle of attack would decrease.

Likewise if you are flying straight and level, and slow down, the angle of attack will increase to create more life. (Assuming you stay in clean configuration).

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It’s pretty cool, comparing these two statements, that increasing the AoA is what “dials in” the net force that accelerates you into the climb. And that once you’re established in the climb, the reduced AoA “undials” the force increase (as you are then proceeding up at constant VS):

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I’m making an Excel spreadsheet for anyone interested in determining the AoA and other aspects.

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thanks for the replies guys. another thought: has anyone noticed that some planes (like the 737 for ex) have “frustrating” rotation physics? that is, when pulling back on the yoke at Vr (rotation speed), the nose barely lifts, and thus one may want to add a bit more pressure. then suddenly the plane “catches” lift and the nose jumps up rapidly. it makes it a little annoying to control; i havent noticed this with other aircraft. particularly wide bodies.

*i swear i dont rotate too early. I spend a good amount of time reading on proper rotation speeds+have simbrief calculate them for me

Fresh from testing two 737 types and a 777, I agree with you the feel is different. With the 777 you feel positive response almost immediately (before Vr for example), and the need to push back down some to keep from over rotating is not there like with the 737.

With the 737 it’s perhaps easy to feel “where’s the rotation?” and end up trying to pull it into the air before it’s ready. Then when it goes up, you have so much rotation control pressure the pitch snaps up too fast to counter control it (stabilize it) in the down direction.

It’s best, when you reach the Vr speed, to mentally apply a fixed, and limited, amount of control pressure, and stop there even though you don’t get an immediate pitch up.

Then wait for the aircraft to accelerate itself into the pitch.

In other words, don’t force the pitch, let it come to you (pitch response gets more sensitive as speed increases, at which point you “catch the wave”).

Then you’ll be ready to push down without having to have lightning reflexes for too fast a pitch up rate.

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