Stability and Control characteristics of the Early Mark Spitfires

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JtD Says:
I don't understand why folks are going nuts about the Spitfires longitudinal instability, it wasn't a problem for any pilot or how NACA put it "the well know long period oscillations have no correlation with the handling qualities of an airplane". Basically, it doesn't matter .

You're repeating what I said yet you try to make it sound as if you disagree with me. Why?

Because I do disagree with you. You confuse apples and oranges between long period oscillations with stick free behaviors and the short period the NACA measured.

The RAE was not stupid. They measured the stick free behavior for a valid reason. You can quickly look at the those graphs to see the Spitfire has positive static and negative dynamic stability stick free. It shows the work load required of the pilot and the ability of the aircraft to maintain equilibrium. The Spitfire was neutral or divergent.

The NACA did not even consider long period oscillation. They only considered short period. Yes, it does matter. It matters so much, it was promptly corrected in the design.

NzTyphoon:

Absolute Nonsense...

Everything is "absolute nonsense" to you, yet you confuse so many things. My advice is to look at the exact conditions and take each statement one at time. It is a scientific report and the language is specific.

You might see that it all fits together and the NACA knew what they were doing. Otherwise, we are forced to concluded that you know more than they do regarding stability and control. I kind of doubt it, though.

Here is a few clues:

1. Guns ports open.....gun ports closed.....(drag picture)

2. Violent pre-stall buffet is not stall motions. It is the the "violent shudder" as noted in the Operating Notes as well as measured data from the NACA

we are presenting and interpreting data without the proper training to do so.

Speak for yourself!

I worked very hard, investing both time and money for my education. Stability and control was covered and testable.

Can you name any aircraft, of any type, in any airforce, that was hands free during WW2, ie wouldn't eventually destroy itself without pilot input in conditions it was divergent?

Most aircraft are not positive statically stable and negative dynamically stable stick free. It is an unacceptable characteristic.

It is a situation where the the aircraft moves toward the trim condition but increases the force on the axis of motion so that it overshoots the mark. The key is our force is increasing with each oscillation. This causes the motion over time to grow larger and the velocity along the axis of motion to increase. Eventually, the forces will overload the aircraft and it will destroy itself.