Planes flipping during agressive defensive moves

[FLS]

Dawger you are guessing. You haven't found anything wrong,  you don't back up any of your claims.  When Hitech explains your error you bow out with a graceless parting shot as if you're an expert beyond our understanding. 

HiTech answered one of your questions.  I'll answer the other. Dobs recovered from post stall gyrations then lost altitude regaining lift for level flight.

[RufusLeaking]

Let's get back to basics.

An aerodynamic stall is when airflow separates from the wing. It goes from laminar flow to turbulent. The point of separation moves from the back of the wing to the front as AOA increases. The stall is the point where the weight of the aircraft (if in level flight) exceeds the lift generated.

The airflow separation reduces the effective area of the wing and reduces lift.

An accelerated stall is when the load on the wing increases to exceed the lift on the wing.

Recovery of a level stall is to lower angle of attack. Pushing the nose over does this, as well as increasing speed and unloading the wing.

Recovery from an accelerated stall is simply reducing the load on the wing by reducing the G's.

Many factors influence the exact characteristics of a stall:

Wing form.
Yaw angle.
Wing condition. Planes are often slightly bent.
Engine torque. I could never get a Cessna 152 to spin against torque.

My point is that modeling the chaotic physics of a stalling aircraft is difficult, if not impossible. Computational Fluid Dynamics is a science all its own. To keep the simulation running at a playable speed, I assume HiTech does some educated approximations of how the planes will depart controlled flight.

*** I post this, because I could not follow or was unfamiliar with some of the theories expressed in previous posts. This is my knowledge, based on my time as an instructor pilot in the USAF.  ***

[FLS]

Good points. 

I think you can simplify the aerodynamic stall definition. The wing stalls when the critical AOA is exceeded.

An accelerated stall is a stall at greater than 1g. You add a radial g load by increasing AOA, when the critical AOA is exceeded the wing stalls. 

For both stalls the recovery is by reducing AOA.

No one is claiming Aces High is more than a simplified physics of flight model but the post stall behavior is more accurate than any other simulation I know of.
 

[RufusLeaking]

Good points. 

I think you can simplify the aerodynamic stall definition. The wing stalls when the critical AOA is exceeded.

An accelerated stall is a stall at greater than 1g. ...

I think we're saying the same things. Critical AOA is the point where lift is less than weight in steady state flight.

... You add a radial g load by increasing AOA, when the critical AOA is exceeded the wing stalls. 

Totally lost me. What is a radial G? Torque?

For both stalls the recovery is by reducing AOA.

Of course. In a level flight, low speed stall, pushing the nose over, aka decreasing AOA, unloads the wing and increases speed. Recovery from an accelerated stall is to unload the wing by easing on the elevator input, essentially decreasing AOA while lowering the load on the wing.

The difference is that recovery from a level flight, low speed stall will almost always require a loss of altitude. Recovery from an accelerated stall can happen in a climb, depending on attitude.

No one is claiming Aces High is more than a simplified physics of flight model but the post stall behavior is more accurate than any other simulation I know of.
 

I agree. The flight model in Aces High is excellent. I particularly like the different 'feel' for different planes. 

[FLS]

I think we're saying the same things. Critical AOA is the point where lift is less than weight in steady state flight.


Totally lost me. What is a radial G? Torque?

Of course. In a level flight, low speed stall, pushing the nose over, aka decreasing AOA, unloads the wing and increases speed. Recovery from an accelerated stall is to unload the wing by easing on the elevator input, essentially decreasing AOA while lowering the load on the wing.

The difference is that recovery from a level flight, low speed stall will almost always require a loss of altitude. Recovery from an accelerated stall can happen in a climb, depending on attitude.


I agree. The flight model in Aces High is excellent. I particularly like the different 'feel' for different planes. 

Radial g is the load factor from turning. I think the expression comes from the force being on a radial from the turn circle center.

I wasn't disagreeing with anything, I was just restating what you said to show that the accelerated stall isn't really different, it just happens at a higher speed.

The USN and USAF sometimes say the same things differently and I'm biased to USN. 

[RufusLeaking]

Radial g is the load factor from turning. I think the expression comes from the force being on a radial from the turn circle center.

OK. Centrifugal force.

The USN and USAF sometimes say the same things differently and I'm biased to USN. 

I won't hold that against you. My dad was in the Navy. I joined the Air Force.

[hitech]

I think we're saying the same things. Critical AOA is the point where lift is less than weight in steady state flight.

A better definition of Critical AOA is the smallest AOA at which any increase in AOA will cause cause less lift. Note, AOA is also not such a simple concept as "A plane will stall at X AOA' because the AOA can be a different angle at any moment in time on every part of the wing.

The way stall is described is different dependent on who is using the information. For a pilot flying a plane normally you speak of stall speed and load factor. Load factor is the increase in lift needed for level flight to maintain a turn at a given bank angle. This is calculated by the equation {  Lift Needed for level flight = Plane Weight / cos(Bank Angle) }. For normal aviation entering the realm of accelerated stalls is not something that most pilots have ever done. Where military pilots and people who fly  aerobatics, stalling at more then 3 g's is fairly common. I am always surprised at the number of pilots I know who have never been inverted in an airplane.

But when you start speaking to engineers who are interested in plane design or flight modeling. Then something like stall speed and load factor are not very helpful unless lots more information is know about a plane design.

As an example stall speed in pilot manuals are normally listed normally listed in IAS. This is because it is most useful to the pilot to know because he can simply look at his air speed indicator and know the number where the plane where stall. But at high AOA IAS can be very different from CAS (Calibrated air speed) and with out knowing CAS any stall calculations based on IAS can be very miss leading.


HiTech

[FLS]

OK. Centrifugal force.

I won't hold that against you. My dad was in the Navy. I joined the Air Force.

We have one of each in the training corps.   

My bias comes from flying with a Navy pilot in Dawn of Aces and Aces High.

[RufusLeaking]

A better definition of Critical AOA is the smallest AOA at which any increase in AOA will cause cause less lift. Note, AOA is also not such a simple concept as "A plane will stall at X AOA' because the AOA can be a different angle at any moment in time on every part of the wing.

I understand. I was getting the impression that some in this discussion were not getting the concepts.

Critical AOA is the smallest AOA at which the any increase in AOA will cause less lift than the load (weight x G.)

Regarding inverted, I've been in an accelerated stall pulling through over the top. 

[JOACH1M]

I just fly the plane. 

[FLS]

I understand. I was getting the impression that some in this discussion were not getting the concepts.

Critical AOA is the smallest AOA at which the any increase in AOA will cause less lift than the load (weight x G.)

Regarding inverted, I've been in an accelerated stall pulling through over the top. 

I haven't seen any definitions where load is part of the critical AOA, that would describe the stall, critical AOA is the point where coefficient of lift no longer increases. Lift will vary with speed but neither is part of the definition of critical AOA.

My dad was a mechanic in the Royal Norwegian Air Force before he became a pilot. He had worked on a Tiger Moth one time and the pilot told him to hop in for a quick flight when he finished. He didn't know the pilot was going to loop and he hadn't strapped in. The pilot didn't notice that but fortunately he kept positive g over the top.   

[hitech]

I understand. I was getting the impression that some in this discussion were not getting the concepts.

Critical AOA is the smallest AOA at which the any increase in AOA will cause less lift than the load (weight x G.)

Regarding inverted, I've been in an accelerated stall pulling through over the top. 

No Rufus the load is irrelevant to critical angle. Lift pre stall increases with AOA, lift post stall decreases with AOA. The point at which it changes is the critical AOA regardless of load. (Note VERY deep into stall lift can increases again. Get one wing on each side of that hump is a flat spin).

HiTech

[RufusLeaking]

No Rufus the load is irrelevant to critical angle. Lift pre stall increases with AOA, lift post stall decreases with AOA. The point at which it changes is the critical AOA regardless of load. (Note VERY deep into stall lift can increases again. Get one wing on each side of that hump is a flat spin).

HiTech

Pardon my return to the basic basics ...

Lift is the vector that counteracts weight in steady state flight. The stall occurs when lift is less than weight. That is, of course, the critical AOA.

A lighter airplane will tolerate a higher AOA before stalling. 'Stalling' being defined as less lift than needed.

It is a matter of terminology. I get that flow separates with increased AOA to the relative wind, period. But, in my mind, a stall is departing controlled flight, where weight and centrifugal force are also factors.

*** Great conversation, by the way. You know what you're talking about, obviously. So does FLS, despite his naval aviation bias. ***

[hitech]

A lighter airplane will tolerate a higher AOA before stalling. 'Stalling' being defined as less lift than needed.

This is very very incorrect.

Not a matter of terminology. Regardless of weight , light plane or heavy plane, they will stall at the exact same AOA.

HiTech

[bustr]

If this is not a game issue, how much will a poor connection influence this erratic behavior being reported?