Stability and Control characteristics of the Early Mark Spitfires

[Crumpp]

If you want to sell instability to me, or anyone else who's got a good understanding of the matter, you'll need to explain how both of the above gradients can be positive in an unstable aircraft and how it was possible to fly the smooth stick fixed turns as shown in figures 17 and 18.

or anyone else who's got a good understanding of the matter,

Your good understanding? Is that with the long period oscillation's your claimed, the slopes of the curves, the difference between stick fixed, stick free, dynamic and static?? I am confused as to where your good understanding is demonstrated.

[Holtzauge]

OK, I see the problem now: What Crumpp fails to understand is that while the actual stick movement is small, figures 17 and 18 show that the pilot uses between 10-20 lb of pull to HOLD the turn. If one looks at the force histogram its apparent that a relatively constant pull force is needed to keep the plane in the turn. So no increased pull force no increased load factor. Wherein lies the big problem? What would be troublesome would be if there was a need to apply a push force or substantial unloading in order not to tighten up the turn once it had been initiated. However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Maybe this is also why we on the one hand have numerous accounts from pilots who actually flew the Spitfire and appreciated it and on the other have a private pilot armchair expert who is of a different opinion based on a myopic and selective interpretation of data.

[Crumpp]

OK, I see the problem now: What Crumpp fails to understand is that while the actual stick movement is small, figures 17 and 18 show that the pilot uses between 10-20 lb of pull to HOLD the turn. If one looks at the force histogram its apparent that that a relatively constant pull force is needed to keep the plane in the turn. So no pull force no increased load factor. Wherein lies the big problem? What would be troublesome would be if there was a need to apply a push force in order not to tigthen up the turn once it had been initiated. However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Maybe this is also why we on the one hand have numerous accounts from pilots who actually flew the Spitfire and appreciated it and on the other have a private pilot armchair expert who is of a different opinion based on a myopic and selective interpretation of data.

However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Spitfire Mk I Operating Notes, July 1940:











By all means continue Holtzauge.

Let's stick to what is definable and measureable, as this is my thread.

[Holtzauge]

Originally Posted by Crumpp

Let's stick to what is definable and measureable, as this is my thread.

Yes, let's stick to that: To begin with follow your own advice: What you posted above is as has now been pointed out numerous times some general advice to the pilot on handling characteristics and hardly qualifies to your own strict limitations to what is definable and measurable so you can remove them from "your" thread.

Now what is pertinent and admissible according to your own definition above are figures 17 and 18 so please enlighten us with how these support your case as opposed to mine and JtD's interpretation above.

[Crumpp]

figures 17 and 18

Why don't read the report about figures 17 and 18?

Here, I will post it once again....



Now, Holtzuage....

I would love to have this conversation with you. Should be a wonderful and refreshing change given your claims to be an engineer.

I wait with baited breath for your measured and definable evidence showing the early Mark Spitfire to have acceptable longitudinal stability by any modern definition. Feel free to use the RAE post war standards, NACA, R-1815A, SF119A, MIL-F-8785, FAR, JAR....

You pick!!

Looking forward to it.

[Glider]

Personally I am waiting for you to supply examples of any WW2 fighter that met modern standards

We know that the Spit didn't but we also know it wasn't a problem. We also know that the DC3 didn't meet the standards and can only assume that the people still flying these aircraft 70+ years after they were designed don't realise that they are so unstable.

We are still waiting for a load of information that you said you had that supported your case.

PS don't claim to have the training or qualifications that you claim to have but IIRC, MIL-F-8785 was mainly short period damping regarding roll, not the longitudinal stability of an aircraft

[Crumpp]

Personally I am waiting for you to supply examples of any WW2 fighter that met modern standards

I have already answered your question. It is in the thread and it is specific to you about this same question.

I am not going to continue to post the information so that you can ignore it when convenient.