So I’ve come to the following statement:
The camber of the wing doesn’t provide a whole lot of lift. It’s main purpose is to delay stall and reduce drag. A flat board also has a lift curve, but it peaks at a much lower AoA.
So not only is AoA important, it’s perhaps the major contributor to lift!?
Your getting close.
Think of a airplane flying upside down. How much does the wing profile contribute to it’s lift?
But that’s a simplification.
Once I had the luck to listen to a discussion between a aeronautical engineer, a test pilot, and a aerodynamics scientist, and none of them could provide the others a full explanation that they could all agree on. They ended that it works. Somehow.
That’s a great anecdote! Thanks. It’s a first hand account similar to what I’ve been reading from a range of sources.
An article in Flying Magazine on the history of airfoils (Airfoils: A Short History - FLYING Magazine) starts with the line: “Let’s be frank. We don’t really need airfoils.”!
A lot of the early history of wings was either no airfoil, or just faking a rough shape of something that seemed to give a bit better performance.
The simplest I can say now is: Newton shows why the force on the wings; Bernoulli shows how.
btw I was checking out the A220 for AoA around cruise. It was settling in to about 2 degrees. As I tried to climb further as high as possible it increased to maybe 3 to 4 degrees. I realized the reason it increased was because the mach number limit becomes a lower and lower IAS as you climb. And IAS represents a constant dynamic pressure. So as my IAS was squeezed smaller, my AoA had to grow.
You said the hornet document uses AoA 720 times.
I don’t know if you can answer these questions:
Are these AoA numbers just a secondary reference for pilots, or are they actually expected to fly by reference to those numbers? In other words the pilot is always checking and knowing their AoA against the goal? And is this universal for most fighters in a way that is absent from subsonic transport aircraft?
Yes, pilots are supposed to monitor their AoA and know which AoA they should have related to their KIAS in certain phases of the flight.
That could be the efficient cruise, or the manual flaps, or to provoke a certain flap setting in auto mode, but 1st of all it is required for landing.
If I remember correctly it is 8.1° when on path and speed (which depends on grossweight and wind conditions) for carrier landings. It is easier to hit a moving flightdeck by speed and AoA from a starting attitude the by sinkrate how it is done
Most Military Jets Display the AoA to the pilot as a indication and precaution of stall.
As far as I know the legacy hornet is the only jet where it is used that excessive, the super hornet has more automation but still requires it.
Just an anecdotal bit here, but as a kid I used to take a sheet of 8 1/2 x 11 or legal paper, do a little bit of a balancing act for a second, and then push it through the air, finger in the middle of the trailing edge, with about 20-35 degrees up pitch, and fly the piece of paper around the room with just the one finger.
Reminds me of the wings on the F-4, and all the jokes about “given enough thrust even a brick will fly”.
A serious point for the Newtonian side, with literally zero airfoil shape.
I’m trying to imagine, if they are targeting AoA as a primary goal, how are they able to control to within a fraction of a degree let alone one degree? Can they really hand fly to a precision of a fraction of a degree (with throttle and pitch)? Or is it the design ideal (for reference) that human flying never hits so exactly as, say, to within a tenth of a degree?
An extreme case might be meteors that enter the atmosphere only to “fly” back into space rather than hit the ground: Watch Meteoroid Bounce Back Into Space - Videos from The Weather Channel | weather.com
Literally a flying rock!
The change in AoA is a fast and easy to follow indication while keeping a specific speed. Way faster then sink rate. When there is a noticeable change in sink rate it is already to late to compensate for a carrier landing. The precision of the required inputs where not the difficulty.
I wonder if fly-by-wire makes it more possible to hold a tighter AoA target than with older fighters?
There are general aviation AoA instruments that show only graphical symbols to show if you’re mostly in the zone or not.
I’m thinking it’s maybe the FCS that does a lot of the work? Considering the old style guages:
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