G-day
I heard about this theory on the control reversal of an aircraft after it breaks the sound barrier. Is this true? if so what are the reasons behind it?
I've searched on Google and only received info about "flutter" which I don't think has anything to do with it. Then thought the next best place would be a flight forum of some sought.
For my mental health's sake please tell me it's not true but if it is I'd really appreciate it if I knew why in depth.
Thanks.
11 Answers
Chief Captain
Thanks for the reply.
This article explained the human error and problems we've had in the past through out the constuction of certain aircraft causing control reversal. It only briefly touched on supersonic speeds and didn't "get to the point" which is the frustrating thing for me. i have since found a few websites which i'll post later which kind of explains it in a little more depth.
This is really kicking me in the head.
thanks for the reply again
just talked to an FA/18 pilot on the weekend and proved that there infact no control reversal at transonic and supersonic altitudes. There is a slit stream effect which defys beouli's law where by the 2 air particles do not meet up on the triling edge on the aerofoil. This causes a low pressure around the trailing edge of the aerofoil making the controls become completely useless. To counter-act this problem they actulally make the "whole tip" (leading edge to the trailing edge) of the wings a combination of ailerons and elevators and they use the same concept for the rudder.
What was experienced by most soud barrior breaking pilots in the early days was something called the mach tuck where by the lift over the aerofoil caused by the sheer speed of the air over it, was so great that they had to fly with their nose down to keep it's altitude. This usually resulted the the plane being obliterated because force is not ment to be exerted on the top face of the aircraft.
*The only way to get control reversal is from human/maintenance error*
Myth Busted
Chuck Jager's movie is incorrect where he elegitly says that there is a control reversal at transonic/supersonic.
Stall, Spin, Crash, Burn then Die
Thanks for the help anyway.
First OfficerAnonymous wrote:
just talked to an FA/18 pilot on the weekend and proved that there infact no control reversal at transonic and supersonic altitudes. There is a slit stream effect which defys beouli's law where by the 2 air particles do not meet up on the triling edge on the aerofoil. This causes a low pressure around the trailing edge of the aerofoil making the controls become completely useless. To counter-act this problem they actulally make the "whole tip" (leading edge to the trailing edge) of the wings a combination of ailerons and elevators and they use the same concept for the rudder.
What was experienced by most soud barrior breaking pilots in the early days was something called the mach tuck where by the lift over the aerofoil caused by the sheer speed of the air over it, was so great that they had to fly with their nose down to keep it's altitude. This usually resulted the the plane being obliterated because force is not ment to be exerted on the top face of the aircraft.
*The only way to get control reversal is from human/maintenance error*
Myth Busted
Chuck Jager's movie is incorrect where he elegitly says that there is a control reversal at transonic/supersonic.
Stall, Spin, Crash, Burn then Die
Thanks for the help anyway.
Where's the factual evidence, or at least, a theory that adds up, in your attempt to prove the wiki article wrong?
"supersonic altitude"?
"the 2 air particles "?
Come on, get your terminology right of you're trying to prove an "encyclopaedic" (that's probably not how it's spelled - sorry) article wrong.
I found this part, for example, much more believable than that what I just read.
the problem occurs when the amount of airflow over the wing becomes great enough that the force generated by the ailerons is enough to twist the wing itself, due to insufficient torsional stiffness of the wing structure. For instance when the aileron is deflected upwards in order to make that wing move down, the wing twists in the opposite direction. The net result is that the airflow is directed down instead of up and the wing moves upward, opposite of what was expected.
And since an F/A 18 most likely is not constructed to suffer from this effect, I wonder how a pilot could dismiss a theory (let's cal it a theory for the moment) like this so easily. What arguments did he give you?
First OfficerI agree with ARD-DC. There is such an element known.
You can get elevator reversal. It is cause when the load/forces on the elevator are large enough to cause a twisting moment on the deflected elevator surface. It causes a reverse in the aircrafts pitch attitude.
You can also get a similar effect on the aileron. It goes without saying that this and the above can only happen when the aircraft is moving fast which would lead to the high forces/loading.
Chief CaptainTartanaviation wrote:
I agree with ARD-DC. There is such an element known.
You can get elevator reversal. It is cause when the load/forces on the elevator are large enough to cause a twisting moment on the deflected elevator surface. It causes a reverse in the aircrafts pitch attitude.
You can also get a similar effect on the aileron. It goes without saying that this and the above can only happen when the aircraft is moving fast which would lead to the high forces/loading.
The date dude........ 🙄
First OfficerDelete
Chief CaptainI highly doubt it, whats the chances, people haven't responded to this for ages and it was past page 1, I don't think many people look past that.
But whatever 🙄
First OfficerDelete
Chief CaptainWell, know im not interested to know, I've seen this before and I have an extreme passion for aviation and have my PPL's. Im just merely saying this is a worthless and outdated topic not worth replying to.
I refuse to post in this topic any further
CaptainHello there,
I can see why you might be concerned about the idea of control reversal after breaking the sound barrier. However, let me assure you that while there is a phenomenon called "control reversal," it's not quite as dramatic as it might sound. Let me explain this in more detail.
Control Reversal is a term referring to an aerodynamic effect that can occur when an aircraft transitions from subsonic to supersonic speeds. This effect does not cause the aircraft's controls to reverse in the literal sense, but it does alter the way the control surfaces respond to input from the pilot.
When an aircraft travels through the air, it generates shock waves, which are disturbances in the air pressure. At subsonic speeds, these shock waves propagate ahead of the aircraft. However, as the aircraft accelerates to supersonic speeds, the shock waves are compressed and travel with the aircraft, creating a shock cone.
This shock cone can cause the aerodynamic center, which is the point where the lift forces on the wings act, to shift rearward. Consequently, the aircraft's pitch stability can decrease, leading to a situation where the pilot's control inputs might produce unexpected or counterintuitive responses from the control surfaces.
For example, in some cases, if a pilot were to input a nose-up command using the elevator, the aircraft might respond by pitching down. This is due to the altered pressure distribution on the control surface, resulting from the rearward shift of the aerodynamic center. It is important to note that this effect is highly dependent on the aircraft's design and the specific conditions at which it is flying.
Modern supersonic aircraft are designed to mitigate control reversal effects through various means, such as supercritical airfoils, variable-geometry wings, and advanced flight control systems. These technologies help to maintain stability and control effectiveness throughout the transition from subsonic to supersonic speeds.
To sum up, while control reversal is a real phenomenon, it is not as alarming as it might initially sound. Advances in aircraft design and technology have made it possible to manage and mitigate these effects, allowing for safe and controlled supersonic flight.
For more information on supersonic flight and control reversal, you may want to check out the following resources:
I hope this explanation provides you with some relief and a better understanding of the subject. Safe flying!
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