Stability and Control characteristics of the Early Mark Spitfires

[Crumpp]

The report alludes to "careful" flying. Does that mean "not careful" flying in the other charts.

Good questions.

No, these where done with "careful flying". If you read the report, they were done with force measurement equipment hooked to the controls.

The pilot could move the stick but when he let go, the equipment held it fast so the forces could be measured.

He could move the stick if needed to keep the accelerations within safe limits.

So, the controls in the test are done with about as careful flying as you can get. Most Spitfire pilot did not have a force gauge holding their controls fixed.

Yet it does not say that is was dangerous flying quality

It is dangerous under conditions the pilot can overload the airframe. That is why you see the incidence of in-flight structural failure's and the warnings in the Operating Notes.

It is dangerous when you need to shoot accurately and it is dangerous when you need to make an abrupt maneuver to avoid and enemy attack.

Yes, it can be controlled by the pilot and mitigated by his skill level. It requires such input.

You have hit upon the entire reason the Air Ministry did not have stability and control standards outside of pilot opinion.

The British were major pioneers in stability and control in the beginning but kind of floundered after World War I.

[Crumpp]

the reason the inertia weights were added was to help overcome a problem with poor cg loading at a squadron level

Again, the RAE may have blamed it on that but they were also behind in Stability and Control research. The NPL pretty much stagnated until the efforts of Gates and Lyons came to fruition post war moving AWAY from the conclusion stability and control could not be defined without pilot input.





The opinion of the NACA was much different and their test aircraft was NOT overloaded and at a normal CG.

[bongodriver]

Notice how the problem was 'tails' breaking and not 'wings' bending that were the main case for structural failure, of course Crumpps highlight there mentions nothing about early Spits and in fact probably is refering to the MkV.

[Al Schlageter]

It is dangerous when you need to shoot accurately and it is dangerous when you need to make an abrupt maneuver to avoid and enemy attack.

Spitfire pilots didn't seem to have that much trouble shooting down German a/c during the BoB despite being out numbered in the air over south-east England.

That is why you see the incidence of in-flight structural failure's and the warnings in the Operating Notes.

There are such warnings for American a/c.

[Crumpp]

Why did they not demand a retro fit of inertia weights to the MK I & II that would have been in the OTU squadrons at the time if it was such a problem?

I know it was later modified with an inertial elevator. They did something to correct it, you can bet.

The fact remains, the RAE skirted around the problem because they had no real estabilished foundation for what to do with longitudinal instability.

Especially when the pilot's opinion ran contrary.

It is really interesting if you like the history of technological development. There was a guy in England who laid down all the math just before World War I. It was in center of pressure and metacenter so his mechanics were not completely correct but all his principles were as well as the use of polynomial co-efficients to describe motion. Professor GH Bryan's really cracked the nut on stability and control.

Some of his conclusion's are used today. The problem was when he tried to explain it, it was so complicated that most engineer's eye glazed over, mouths came open, and the drooling begain. Then, some pilot would hop in the same plane his big complicated set of equations had predicted was unstable and fly off in it.

You can control an airplane that is unstable, especially the long period oscillation the NPL became focused on. The 1903 Wright Flyer was so unstable, the techique used to land it was to fly close to the ground at low velocity and let the skids touch on the downward oscillation.

You could not estabilish a stabilized approach that is common in todays airplanes.

They flew extremely unstable aircraft all the time in the early days of aviation. The velocity and forces were low enough that stability and control just was not that important.

the major flight characteristic ever present is the feeling that if you took your hands off the stick or your feet off of the rudders, the Eindecker would turn itself inside out or literally swap ends." He also indicates that the all-moving surfaces continually hunted back and forth with an attendant feedback into the pilot's hands and feet. These characteristics describe an aircraft that by modern standards would be considered unpleasant to fly, would be unlicensable, and certainly would inspire little confidence in the mind of the pilot.

http://www.hq.nasa.gov/pao/History/SP-468/ch2-2.htm

That all changed with the advent in the powerful monoplane fighters of World War II. The speed and forces involved pushed the science of stability and control to the forefront.

[Crumpp]

There are such warnings for American a/c.

Really, by god....don't model it, we might see "porked" american fighters....



Quick, withdraw the facts about the Spitfire!!! Run!! There will be revolution!!