A newbies impression of the 109 and spit

[Crumpp]

You're arguing with non-engineers...

It is funny that Morgan and Shacklady quote several pilots who disliked the Spitfire's elevator after the longitudinal instability was fixed by the addition of bob-weights.

They felt it ruined the feel and made the elevator sluggish.

I laughed when I read it.

I bet it did make it feel sluggish if you are used too 3/4 inch stick travel for the available Angle of Attack at 5 lbs per G in neutral or just statically stable!!

[NZtyphoon]

Originally Posted by von Brühl

You're arguing with non-engineers...

Nope, the problem here is that someone who claims to know something about aviation can also make a blanket claim that the Spitfire was an inherently dangerous aircraft, based on two reports which say nothing of the sort.

What they do say is that it did not reach certain NACA standards which had been introduced in 1941 Reference 1. REQUIREMENTS FOR SATISFACTORY FLYING QUALITIES OF AIRPLANES can be found here

Originally Posted by Crumpp

It would help if you understood everything that report says instead of select phrases out of context. If you can't do that , it is practically impossible to hold a discussion.


If you read the report, it states the conditions the aircraft exhibited a very harsh stall. One of those conditions would be in a steep bank with gun ports open. Under those conditions, the aircraft would develop a roll instability and resulting spin.

The conditions matter in aerodynamics.

Yes the Spitfire gave very good stall warning. That large buffet zone comes at a price in diminishing turn performance.

Longitudinal Stability has nothing to do with stall characteristics except to determine how fast the pilot can move the wing through its useable angle of attack range.

The NACA rated the Spitfire as having unacceptable longitudinal stability and control in all conditions of flight. It is either neutral or unstable and this was corrected with bob weights in later marks.

That is not a bias, it is just a fact. None of these aircraft were perfect regarding stability and control. Some were worse than others and it is a fact the early mark Spitfires exhibited a dangerous longitudinal instability. It was an infant science when they were developed.

Nowhere in any of these reports does it state the Spitfire was dangerous. Strangely enough I actually agree with Kurfurst that it did have a sensitive elevator in certain conditions, but, whatever longitudinal instability it did have was controllable, and most pilots learned to handle it, including wet-behind-the-ears trainees transitioning from the Harvard, which could bite if pushed the wrong way.

All fighters are supposed to have a certain amount of controllable instability, otherwise they would not be able to manoeuvre effectively. Remember the BE2? This was an aircraft which was designed to be stable about all axes and it failed miserably as a fighter, and it was all too easy to shoot down because of that built in stability, although it made a great observation platform which was its original purpose. On the opposite pole there was the Camel which was dangerous to its pilots, although still effective when handled properly.

[CaptainDoggles]

Guys, aircraft stability is not something that's subject to interpretation. Either an aircraft is stable about a particular axis or it is not.

Even NACA agrees that the Spitfire V did not have positive longitudinal stability.

...yet neither of these famous aircraft had the specified levels of the most basic stability of them all, static longitudinal stability...

"Stability" is a quantifiable property, not a subjective classification. An aircraft that is not statically stable can still have good flying qualities. To say that the Spitfire was not statically stable is not to say that all the pilots praising the Spit's handling qualities were wrong.

You guys are getting so caught up in your quest to prove Crumpp wrong that you're losing sight of the facts.

[bongodriver]

Even NACA agrees that the Spitfire V did not have positive longitudinal stability.

Maybe so but this isn't any indication of the 'dangerous instability' crumpp is pushing.
all it means is the spitfire was agile....a desireable quality in a fighter non?

[CaptainDoggles]

Originally Posted by bongodriver

Maybe so but this isn't any indication of the 'dangerous instability' crumpp is pushing.
all it means is the spitfire was agile....a desireable quality in a fighter non?

No, not "maybe so".

The Spit V had zero stability, this is fact.

[bongodriver]

Originally Posted by CaptainDoggles

No, not "maybe so".

The Spit V had zero stability, this is fact.

So how were mere humans able to fly them? total instability is the realms of 5th generation fighter jets that need computers to fly them.

Sorry but you guys are blowing it out your asses if you claim the spitfire had 'no' stability.

[JtD]

Neutral static longitudinal stability doesn't mean no stability at all.

[CaptainDoggles]

Originally Posted by bongodriver

So how were mere humans able to fly them? total instability is the realms of 5th generation fighter jets that need computers to fly them.

Sorry but you guys are blowing it out your asses if you claim the spitfire had 'no' stability.

I think maybe you should go learn about aircraft stability before you tell me I'm "blowing it out my ass" because you are incorrect.

There are three classifications of static stability: positive, negative, and neutral (or zero).

Don't be so hostile.

[bongodriver]

Originally Posted by CaptainDoggles

I think maybe you should go learn about aircraft stability before you tell me I'm "blowing it out my ass" because you are incorrect.

There are three classifications of stability: positive, negative, and neutral (or zero).

Don't be so hostile.

actually theres static and dynaminc, I don't need to learn anything from people claiming the spitfire was 'unstable', and believe me static (or neutral) stability is by no means unstable.

Sorry if I sound hostile, no intention but I understand.

[CaptainDoggles]

Originally Posted by bongodriver

actually theres static and dynaminc

Edited my post, as I was typing too fast. There are three conditions of static or dynamic stability: Positive, Negative, and Neutral. The spitfire had neutral (when i was in school we used the term "zero") static longitudinal stability. An aircraft can only be said to be statically stable if it has positive stability.

I don't need to learn anything from people claiming the spitfire was 'unstable', and believe me static (or neutral) stability is by no means unstable.

It's not my fault if you're misusing the accepted terminology. I've provided a reference from the National Advisory Committee for Aeronautics that supports my case.

Go look up a reference that proves me wrong, showing the spitfire had positive static stability.