Stability and Control characteristics of the Early Mark Spitfires

[6S.Manu]

Originally Posted by robtek

The missing harmony must be reflected in game, regardless about that, that many will be gaming the game and correct the joystick profiles accordingly.

And more, are longitudinal and lateral oscillations in the game?

[lane]

Originally Posted by robtek

The missing harmony must be reflected in game, regardless about that, that many will be gaming the game and correct the joystick profiles accordingly.

Indeed, from here:

[Sandstone]

Originally Posted by 6S.Manu

In my opionion this thread demostrate that Spitfire had some characterics who actually were dangerous if the pilot was not experienced... the ability to reach a great amount AoA in so little time (given the low stick forces) CAN BE dangerous if the pilot is not really well trained.

The Spitfire was flown by pilots who were not well trained by modern standards. The need to get pilots into action meant that training was relatively short and pilots were entering action with only a few hundred hour on type. However, I'm not aware of accounts describing the Spitfire's elevator response as a major challenge to the pilot. I'm certainly not aware of any reports of pilots pulling the wings off or losing control because of the elevator response. It would be interesting to find some if they exist.

I suspect some of the confusion evident in this thread is because:

i) Some posters (including, it appears, the OP) seem to regard stability as existing only in extreme values, so that an aircraft is either stable and thus perfectly safe, or unstable and thus horribly dangerous. However, the truth seems to be that while the Spitfire was indeed longitudinally unstable, this instability presented almost no problems even for relatively inexperienced pilots. IIRC, one of Crumpp's posts also describes the DC-3 as being unstable. Again, it probably was, but there is little evidence that this caused problems for its pilots. In fact, it's worth noting that most aircraft actually are spirally unstable (i.e., left to themselves they will ultimately end up in a spiral dive), but the instability mode is so slow to develop that the pilot isn't even usually aware of it.

ii) Some posters regard instability as a desireable characteristic for a fighter aircraft as if it promotes manoeuvrability. But in technical language "unstable" is not the opposite of "unmanoeuvrable" (if by the latter we mean not agile). An aircraft can be simultaneously unstable and unmanoeuvrable (DC-3), or it can be stable and manoeuvrable (Pitts Special) or it can be unstable and manoeuvrable (Spitfire), or stable and unmanoeuvrable (almost any large aircraft). Unfortunately, popular accounts and casual useage mix these terms up and sometimes use unstable to mean manoeuvrable, or imply that instability is necessary for manoeuvrability. It isn't.

Whether any of this can be represented in a flight sim is a different matter. The lack of force-feedback, short PC joysticks and the need to allow response curves all suggest to me that it would be tricky at best.

FWIW, there have been attempts to relate the pilot's experience of how easy an aircraft is to fly to deficiences in stability or other aerodynamic deficiencies of the design. One such method is the Cooper-Harper scale for evaluating aircraft flying qualities (often used by test pilots). The scale considers the aircraft characteristics and how they impose demands on the pilot in selected tasks or required operation. The scale runs from 1 (good) to 10 (very bad), with 1 defined as "pilot compensation is not a factor in desired performance" and 10 meaning that "control will be lost during some portion of required operation". On the scale, 3 is defined as an aircraft characteristic which exhibits "some mildly unpleasant deficiencies" and imposes demands on the pilot such that "minimal pilot compensation (is) required for desired performance". The scale defines 4 as requiring "moderate pilot compensation". The division between deficiencies warranting improvement is at the 3/4 boundary (not required for 1-3, required for 4-10). I suspect that the longitudinal instability of the early Spitfire if assessed on the scale would be on that 3/4 boundary - i.e., it warranted improvement but was not seen as a major deficiency.

It would have been useful if the OP had clarified some if these matters at the start.

[ACE-OF-ACES]

Originally Posted by taildraggernut

Quoted for the absolute and glaring truth of the whole matter, but I would argue that confusion is perhaps what the aim of Crumpp's thread is all about, confuse everyone with science so they feel insecure about opposing your position and I think that is almost as glaringly obvious.

Some shady lawyers use the same tactics in court.. It is the kitchen sink approach where they through everything at the wall and go with what ever sticks.. And during the process they hope and pray that everyones focus is on all the things that didn't stick and hit the floor

[robtek]

Isn't that the same tactic as the one you are using now, AoA?

[CaptainDoggles]

Originally Posted by taildraggernut

Heres a couple of links that clearly show the relationship between stability and maneuverability i.e. the relationship is inverse, this is what USN student pilots are being taught, I am fairly sure the USN currently are using 'adopted' standards

http://navyflightmanuals.tpub.com/P-1231/P-12310068.htm

http://navyflightmanuals.tpub.com/P-1231/P-12310031.htm

So lets get all this in perspective, longitudinal instability does 'not' mean the aircraft is difficult to control, and it 'does' mean the aircraft is more manouverable, it's all about how far on the scale you go, and the Spitfire just sits on the slightly unstable end, the 109 would sit slightly on the stable end.

I will just quote Crumpp again so you can draw your own conclusions wether he really knows what he is talking about or just has a sinister agenda.

The very first line from the very first link you posted says the following:

The T-45 is a very stable aircraft yet is fully maneuverable

My eyes hurt from rolling so hard.

[fruitbat]

see you didn't get past the first line then.

[CaptainDoggles]

Originally Posted by fruitbat

see you didn't get past the first line then.

Just like Sandstone pointed out above: Everyone thinks that maneuverability requires instability. That is false, and even the US Navy says so.

Otherwise, they would not have described the T-45 as "very stable yet fully maneuverable". A child can understand this.

[fruitbat]

Originally Posted by CaptainDoggles

Just like Sandstone pointed out above: Everyone thinks that maneuverability requires instability. That is false, and even the US Navy says so.

Otherwise, they would not have described the T-45 as "very stable yet fully maneuverable". A child can understand this.

A child would be able to read to paragraph 5, unlike yourself it appears.

[ACE-OF-ACES]

Originally Posted by robtek

Isn't that the same tactic as the one you are using now, AoA?

Nada, nicks, nine, nope