Do airframes bend?

[Kurfürst]

Originally Posted by cheyennepilot

I did some tests two-three patches ago, trying to find if wings bending was present and we have the "aileron reversal" effect modelled ingame. My conclussions were that no bending is modelled, from a FM point of view. Graphically I dont know because I dont care too much. This test was in a 109.

You can't possibly get to the point of aileron reversal. AR means that the wings twist so much from the force that they start to act like huge ailerons and start to roll in the opposite direction. But this occurs at only such high speeds, well above diving limits, that is not a concern. The Spitfire, which had a relatively low - compared to other fighters - calculated AR point of about 510 mph IAS iirc, at which airspeed it is supposed to roll in the opposite direction. The reason for that was the wing's structural design, which wasn't very stiff. But that wasn't that much a problem since the plane was limited at around 450 mph IAS in dives.. iow, you were beyond the safety limit when this happened.

But since AR is not a on/off function but sets in gradually, its a good indicator of how high speed (negatively) effects the rate of roll.

[Sternjaeger II]

well apparently you can reach flutter speed in the Bf110, wonder if you can achieve it in other planes too.

[SG1_Lud]

Originally Posted by cheesehawk

But wouldn't the changing speed, energy bleed, etc screw this up? I'm assuming you mean turning, which wouldn't be constant radius, or can you set it up so you find the apex and speed? Interesting.......

You cannot get exact values, but you can tell if you are above certain G. For example, imagine you could put an imaginary semicircle of radius R and turn inside it. You are underestimating the G's if in the formula

a = V ^ 2 / r

You use r = R


So you cannot say your exact G, but you can tell if you were above some specific value or not.

The specific value in this case would be around 7G, as has been discussed in another thread (http://forum.1cpublishing.eu/showthread.php?t=16362), because this is the value at which one could say that a correct DM would start to model structural damaging of the plane ( a spitfire in this case) in normal load conditions. So basically my test was not : how many G can I pull? But, Can I pull more than 7G and have no damage? The aswer to this later question was, yes, it can be done and you wont notice damage in the aircraft (spitfire I state again). And more than that, I found that I could open the flaps at 400 mph pull more than 7G and no damage was present either.

You can make this tests and see, big radar towers are 200m height I estimate, and you can use and array of them and the grid in FMB to set references in place of that imaginary circle I was describing above.

But I feel that this, that was a side note in my post, maybe is hijacking the OP topic, so mabe is better to discuss it apart, I'd love to see other guys results.

[SG1_Lud]

Originally Posted by Kurfürst

You can't possibly get to the point of aileron reversal. AR means that the wings twist so much from the force that they start to act like huge ailerons and start to roll in the opposite direction. But this occurs at only such high speeds, well above diving limits, that is not a concern. The Spitfire, which had a relatively low - compared to other fighters - calculated AR point of about 510 mph IAS iirc, at which airspeed it is supposed to roll in the opposite direction. The reason for that was the wing's structural design, which wasn't very stiff. But that wasn't that much a problem since the plane was limited at around 450 mph IAS in dives.. iow, you were beyond the safety limit when this happened.

But since AR is not a on/off function but sets in gradually, its a good indicator of how high speed (negatively) effects the rate of roll.

Convinced for the spitfire, thank you very much for your explanation Kurfürst

[Skoshi Tiger]

Originally Posted by Grand_Armee

Heinz Knoke took off to fight in a 109G with a bent frame once...I remember from his book.

An RAAF pilot John Haslope attached to 165 Squadron RAF. Bent his Mustang III when he shot down a Me 163 Komet on 10 April 1945. (Only non-US pilot to shoot one down)

He thought his plane was handling funny after he pulled out of the dive chasing the Komet and once on the ground they found out he had added an extra 5 degrees to the dihedral.

Cheers!

[RE77ACTION]

Originally Posted by Kurfürst

You can't possibly get to the point of aileron reversal. AR means that the wings twist so much from the force that they start to act like huge ailerons and start to roll in the opposite direction. But this occurs at only such high speeds, well above diving limits, that is not a concern. The Spitfire, which had a relatively low - compared to other fighters - calculated AR point of about 510 mph IAS iirc, at which airspeed it is supposed to roll in the opposite direction. The reason for that was the wing's structural design, which wasn't very stiff. But that wasn't that much a problem since the plane was limited at around 450 mph IAS in dives.. iow, you were beyond the safety limit when this happened.

But since AR is not a on/off function but sets in gradually, its a good indicator of how high speed (negatively) effects the rate of roll.

I'm not an expert, but is this the same thing that happens currently to the BF110 when you go beyond 500 kph. At 550 kph the plane is almost out of control with its twisting and drifting.

[Kurfürst]

Originally Posted by RE77ACTION

I'm not an expert, but is this the same thing that happens currently to the BF110 when you go beyond 500 kph. At 550 kph the plane is almost out of control with its twisting and drifting.

I guess the 110s case is a simulation of control surface flutter. Simply to put, the airflow over control surfaces gets turbulent, and it starts to vibrate and deflect the control surface increasingly wildly. Its a very dangerous situation, as this would vibrate the whole structure and sooner or later it will structurally fail and fall apart.

The odd thing about the 110 that this starts well below the official diving limits of the plane since the recent patches..

[RE77ACTION]

Originally Posted by Kurfürst

I guess the 110s case is a simulation of control surface flutter. Simply to put, the airflow over control surfaces gets turbulent, and it starts to vibrate and deflect the control surface increasingly wildly. Its a very dangerous situation, as this would vibrate the whole structure and sooner or later it will structurally fail and fall apart.

The odd thing about the 110 that this starts well below the official diving limits of the plane since the recent patches..

Thank you for your answer because I was really wondering. If I remember correctly, the label in the cockpit says something about 700kph.

[Sternjaeger II]

they should really really do something to address this, airframe flexibility is a huge issue in aerodynamics..