Aces High Bulletin Board
Help and Support Forums => Aces High Bug Reports => Topic started by: swareiam on April 20, 2007, 07:50:34 AM
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I have noticed several times now since the new 2.10 update a control surface lock up problem. It seems as I am approaching my opponent at high speed and high angle of attack my control surfaces lock up, but only after I fire my first burst. It leaves the aircraft dead stick for up to ten second or I hit the ground, which even comes first. Even if I am dead on aim it still seems to lock up. It only seems to apply when I am going into a vertical attack. At low altitude I fly the Seafire MKII. I thought it may have been a problem with that model. But, then I noticed it happening with the P-51 at low altitude as well. It is a extreme problem when there is a huge FURBALL. This is because you know their is someone trailing you. Has anyone else experience this problem? Just interested to know...:confused:
Cheers:aok
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It's called compression.
When an aircraft is in a high speed dive, the airflow over the wings of the aircraft can actually exceed the speed of sound. This transonic airflow creates a shockwave and a barrier that disrupts the flow of air over the control surfaces. This causes a dramatic loss in control efficiency and is known as compression.
To counter compression, speed must be reduced. Increasing drag and decreasing thrust will slow the plane. Once the aircraft slows, control will be regained.
In other words, you're diving to fast. :)
If you're losing control at slow speed, well.. you're just going to slow.
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Originally posted by NHawk
When an aircraft is in a high speed dive, the airflow over the wings of the aircraft can actually exceed the speed of sound.
Er.. no, it can't. Not on any WW2 aircraft, anyways.
However, NHawk is right. It's called compression. you're going so fast that it requires more force to move your control surfaces than you can humanly apply to your aircraft. Note the "Trim Elevator Up" key is "I" on the keyboard. If you're nose down and compress, trim your nose UP with elevator trim. Once you come out of the dive you can slow down enough to regain control.
Also, throttle back when you dive, to prevent this. It usually only happens at VERY high speeds. Some aircraft are affected at lower speeds (p38s, 109s) but for the most part it just means you're going too fast.
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Originally posted by NHawk
It's called compression.
Yep, I am very familiar with compressibility, which this is not. The lock up occurs going up while your aircraft is starting to decelerate. Compressibilty generally occurs going down and increasing in speed. This is nothing like compressibility. There is control up until the point where the weapons are discharged and the lock up occurs.
Cheers:aok
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Originally posted by swareiam
Yep, I am very familiar with compressibility, which this is not. The lock up occurs going up while your aircraft is starting to decelerate. Compressibilty generally occurs going down and increasing in speed. This is nothing like compressibility. There is control up until the point where the weapons are discharged and the lock up occurs.
Cheers:aok
I'd say film it and send it in.
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Originally posted by NHawk
I'd say film it and send it in.
I really don't think there is anything to record. A frontal view of the aircraft seemingly stalling, rolling over and heading for the ground. I can audio record myself saying "WHAT THE $%$@", but that's about it. I suppose that anything you want is worth making the effort for.
Cheers:aok
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HTC can read a film with a better film viewer. They can pick it apart and figure out exactly what's happening in the code. Stuff we can't see in our film viewer. Can't hurt to send one in.
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Originally posted by Krusty
HTC can read a film with a better film viewer. They can pick it apart and figure out exactly what's happening in the code. Stuff we can't see in our film viewer. Can't hurt to send one in.
No, your right. It could actually fix a very remote bug of some sort. I'll make the film and send it in.
Thanks...
Cheers:aok
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could be a joystick problem, something crossed so when your trigger is pressed it messes your controls up.
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Originally posted by zlehmann
could be a joystick problem, something crossed so when your trigger is pressed it messes your controls up.
That is possible. But it didn't start until I installed the 2.10 update.
Cheers:aok
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do you use any controller profile software? something that sets your joystick buttons to map them to your keyboard buttons? sometimes those will mess things up cuz youll push a button you have mapped to your bombs on the joystick in the game, but your profiler will have it mapped to your flaps or something.
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Originally posted by zlehmann
do you use any controller profile software? something that sets your joystick buttons to map them to your keyboard buttons? sometimes those will mess things up cuz youll push a button you have mapped to your bombs on the joystick in the game, but your profiler will have it mapped to your flaps or something.
Hmmm, The answer to the question is yes. I use a CH Products CombatStick. The only problem with that theory is in any other configuration i.e stright and level flight or combat in a horizontal plane, it works just fine. To top that off, this anomaly doesn't happen consistently. Every now and then, but usually in the thick of combat.
Cheers:aok
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sounds like a short in the stick to me. once a certain threshold on the stick being pulled back is reached it shorts out and nullifies the single your stick is sending.
i know the Z axis on my stick is all messed up and if i try to rudder left i get all sorts of weird anomolies with the axis readings.
see if you can fly around using the mouse or a spare stick to see if it keeps happening. thats the only real way to find out for sure if its a software or hardware issue.
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Originally posted by NHawk
When an aircraft is in a high speed dive, the airflow over the wings of the aircraft can actually exceed the speed of sound.
Originally posted by Krusty
Er.. no, it can't. Not on any WW2 aircraft, anyways.
Nothing wrong with NHawks description of what happens with the airflow at critical mach.
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Originally posted by Murdr
Nothing wrong with NHawks description of what happens with the airflow at critical mach.
You're right. I believe what Krusty is trying to say is that WWII aircraft that had compressibility issues for example the P-38, reached the compressibility envelope well before mach speeds.
Cheers:aok
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I'm pretty sure it's been proven that no WW2 airplane could near the speed of sound. Not even the fastest jets. Especially not props (not with the huge air brake of a prop on the nose). They would shear the prop/engine/wings off and fall apart well before nearing mach1.
EDIT: I've not read anything about wing shearing, but some hurricanes came pretty damn near to it, had to be written off. Props would rip off at the gearbox, damaging the engine in the process, possibly taking it with.
EDIT2: Sorry, don't mean to hijack a problem-solving thread, I'm just goingto let it drop.
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I know what he was getting at, but he was correcting something that was not said. Just pointing out that NHawk said "airflow over the wings of the aircraft can actually exceed the speed of sound" which is exactly what happens when an airfoils critical mach is reached. That is correctly stated what compression is. Speed of the airflow, and speed of the aircraft are two different things.
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You dont need to go beyond mach1 to have supersonic airflow over an airfoil.
The air is accelerated over the cambered upper surface and is much faster than the aircraft. Most jet airliner's today are limited to around Mach 0.8-0.9 cause at this speed the wing is already approaching mach1. Strap jets on a Cessna 152 and it will probably enter supersonic speed airflows at around Mach 0.4
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Thank you Murdr and Hazard. I didn't want to start a battle of knowledge. :)
The airflow over the wings begins to reach supersonic speeds at around mach 0.7. Which is around 532mph at sea level. That speed decreases with altitude. That's why you're usually already in compression long before you feel it's full effect. You're diving from high altitude, where the compression speed is much lower thinking all is good until you try to pull up.
Many WWII aircraft actually reached compression at much slower speeds than others. The 109 and Zero come to mind right away. The basic rule of thumb is the lighter the aircraft the sooner it compresses. However wing and control design is probably the main factor. Hence why a Cessna would compress earlier.
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Even if supersonic airflow is possible for ww2 planes, its definitely not a factor what causes "regular" compression. Airflow pressure on controls and human's strenght is a factor.
Take a thought, why trims ever help against compression? Or why P-38L dont suffer from compression so strong as earlier versions?
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Originally posted by Oleg
Even if supersonic airflow is possible for ww2 planes, its definitely not a factor what causes "regular" compression. Airflow pressure on controls and human's strenght is a factor.
Take a thought, why trims ever help against compression? Or why P-38L dont suffer from compression so strong as earlier versions?
When an aircraft is in a high speed dive, the airflow over the wings of the aircraft can actually exceed the speed of sound. This transonic airflow creates a shockwave and a barrier that disrupts the flow of air over the control surfaces. This causes a dramatic loss in control efficiency and is known as compression.
That is all I'll say. ;)
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Probably we interpret words "control efficiency" in different ways ;) My interpretation is "can move but dont works", yours is "cannt move" if i understood you correctly.
Anyway, supersonic airflow absolutelly unnecessary for compression. Early war planes was compressed at ridiculous speed, like ~450-500 kmh, where is no way airflow can exceed speed of sound i believe.
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Originally posted by Oleg
Even if supersonic airflow is possible for ww2 planes, its definitely not a factor what causes "regular" compression. Airflow pressure on controls and human's strenght is a factor.
Take a thought, why trims ever help against compression? Or why P-38L dont suffer from compression so strong as earlier versions?
See "critical mach" (http://en.wikipedia.org/wiki/Critical_mach)
(http://upload.wikimedia.org/wikipedia/en/1/1c/FAA-8083-3A_Fig_15-9.PNG)
If you look at what happens with the airflow in the figure, you'll might be able to picture that there is significant air pressure on top of the fore of the wing. On the aft of the wing, there is a separation of airflow which allows increased positive pressure on the bottom aft of the wing.
So you have a net twisting force on the wing which causes the plane to nose down. This is the source of high speed control problems for P-38s and P-47s. To deal with that problem, dive flaps were added under the wings. The dive flaps change the shape of the wing, and therefore the airflow around it. While the transsonic shockwave still forms with the dive flaps deployed, the change in airflow moves its formation further aft on the wing. So the net pressure forces on the wing are not pushing the aft of the wing up.
The shape of the foil and air density are what determines at what speed the shockwaves will start to form. The P-38 and P-47 have thick cords, resulting in a low critical mach. Air is being displaced by a solid object, and the shape of the object is going to determine how fast the air is going to accelerate while being displaced. But it can be accelerated to a speed faster than what the object itself is traveling when the shape is forcing it "out of the way" faster than it can efficently flow.
You can have transonic shock waves form around stabs and control surfaces too which can cause them to be "heavy". This I believe is what happens in the case of a 109 for example.
Compression is often used genericly for any high speed control problem, but from a technical stand point it's often misused.
I hate to hijack threads, but I also hate to see good information being cast into doubt, when I know the info is correct. And its not a matter of a knowledge battle either. It's a matter of the passer-by not being left with bad information.
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Murdr, I'll just add one more thing that probably should have started your last post.
Air is always flowing over the top of the wing faster than it is flowing below the wing. This is what causes lift. Now,.... If you look at what happens with the airflow in the figure, you'll might be able to picture that there is significant air pressure on top of the fore of the wing......
Thanks again Murdr. :)
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Thanks for the aerodynamics lesson guys. But, has any of you experienced the initial problem of control surface lock up? I have also experienced it in some cases recently in straight and level flight during LOW speed dog fight. The control always seem to come back after approximately 10 sec, which in most cases is too late.
Cheers:aok
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Originally posted by swareiam
Thanks for the aerodynamic lesson guys. But, have any of you experienced the initial problem of control surface lock up? I have also experienced it in some cases recently in straight and level flight during LOW speed dog fight. The control always seem to come back after approximately 10 sec, which in most cases is too late.
Cheers:aok
Sorry we got so far off track. ;)
There's only one thing I can think of and that's if your connection is through a USB port and your stick is on a USB port. The two may be conflicting or overloading the USB part of your system.
One other thought, do you get the dreaded "Don't move your controls so quickly" (or something like that) message in the text buffer? The 10 second freeze is about right for that.
Just a couple of thoughts. Probably not right, but it's worth a shot.
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Originally posted by NHawk
One other thought, do you get the dreaded "Don't move your controls so quickly" (or something like that) message in the text buffer? The 10 second freeze is about right for that.
I know the message that your speaking of, but not in this case. It usually happens as you're zeroing in and shooting off your first volley. A wide turn of sorts manuvering to lead your shot onto your opponents nose.
Anyway, however infrequently it happens it has definetly cost me a few kills at this point. Otherwise, I really do enjoy this game and the comradeship that you gentlemen provide. See you in the arenas and thanks for your input. :)
Cheers:aok