AOA When Pulling Gs
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If a fighter is at a particular airspeed and altitude, flying at 1G, it will be flying at a particular AOA. If the pilot pulled 2Gs and remained at the same airspeed and altitude, is it possible to determine what the AOA will increase to? I would like to create an Excel spreadsheet that has AOAs at 1G in one column, and what the AOAs will increase to in a 2G column, 3G column, 4G column, etc.
Thanks for the help,
Starfighter
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Hey starfighter, there isn’t a simple relation to help you out, the AoA of the F16 is controlled by the FLCS due to the many variables in play. Depending on what you’re trying to do, you can either try to sample the values from BMS upto the limit of constant specific energy (when at full A/B the aircraft cannot maintain speed) or be a bit more thorough about it and have a look here:
EDIT: https://www.benchmarksims.org/forum/content.php?135-Flight-Model-(FM)-Developer-s-Notes-Part-3
I would say what you would need approximately, to get a simplified result, is:
a) lift coefficient curves as a function of AoA (graph on page 102 of NASA-document)
b) model the standard atmosphere-density as a function of altitude, apply the lift coefficient to that condition and velocity to get a force
c) calculate inertial g-forces induced by a pullup of x-alpha w.r.t. the free-stream (centrifugal force)
d) tabulate the results for all altitudes and g-forces.Assuming you are not an aeronautical engineer, see Anderson’s Introduction to Flight for reference;) I am so I love this stuff, so perhaps I’m getting carried away here, but like I suggested, maybe it’s simpler to just spend some time sampling.
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Whatever doubles the C-L which is double the lift double the acceleration. You want a C-L vs. Alpha graph. It’s gunna be practically linear through 10 AOA.
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These thought experiments are fun.
Angle of attack is the angle between the wing’s chord line and relative wind.
Of course, having momentum or inertia, the aircraft isn’t instantly going to change direction, even when applying pitch up, and hence AoA increases. The momentum changes with mass and speed, so I would say mass is a major important factor here as well.
Correct me if I’m wrong, but in your 1G setup:
Let’s say Airspeed is constant, altitude is being kept level, and the aircraft is experiencing 1G such that it would correspond to a certain Angle of Attack. Well… that is because at a certain airspeed, with the correct angle of attack, you are producing lift that equals the weight of the aircraft, no? That’s why the aircraft is kept at constant altitude.
So factoring weight: If weight increases, then the altitude would drop at the same AoA/Speed as before. So either: A Speed must increase, or B, AoA must increase. For either to work, additional thrust is needed to maintain situation A or B.
As others have said, altitude isn’t really important in aerodynamics, it’s more specifically atmospheric density, which changes with pressure, humidity, temperature etc.
I’m no engineer, only a mortal mechanic so I only know the basics.
Good luck figuring it out though!