Stability and Control characteristics of the Early Mark Spitfires

[6S.Manu]

Originally Posted by Crumpp

Feel free to point out where the manual states a fighter should be unstable.

I feel "standards" can be misleading. How should a fighter be?

Standards are used to hold down the aircraft characteristics with an "ideal one" in mind.

But as Tomcat says "It's a matter of philosophy from the manufacturer and the air forces using it."

So the longitudinal instability of an airplane can be required by some airforces (more or less instability) and totally avoided by other.

One can produce an highly dangerous airplane that is really effective (look at the Tempest) while other can design a safer plane that influences greatly the pilot's range of manoeuvre.

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. Above all if the manoeuvres were made by sharp actions on the stick. The pre-stall warning could easily alerts the pilot if he was entering in the turn smoothly, but since it raised only a pair of mph over the stall speed I really don't think that it could be recognizable during a sharp turn that could easily end in a violent stall.

Because of this there were pilots afraid to turn tightly.

It's like the drifting capability of a car: some capable pilots can recognize the limit and containing a loose car from spinning but an average pilot will not always succeed in it and will find himself with the car pointed at the wrong way.

Then we can talk of "aiming" in a longitudinal unstable aircraft...

[winny]

Like I said before... Now all we need is for some data for the actual in game aircraft, instead of a MK I that is too early and a MK V which is too late...

[taildraggernut]

In my opionion this thread demostrate that Spitfire had some characterics who actually were dangerous if the pilot was not experienced

It's Ok to have an oppinnion, my oppinion is that the stability was not a problem given the actual pilots who were flying the aircraft at the time had the bare minimum time on type and weren't ripping the wings off the aircraft, just my oppinion but the Spitfire was not famed for being an aircraft 'only experts' could fly.....quite the opposite in fact.

[robtek]

About stability, the best one could have in a fighter is neither stable or instable but neutral stability, afaik.

[robtek]

Originally Posted by taildraggernut

It's Ok to have an oppinnion, my oppinion is that the stability was not a problem given the actual pilots who were flying the aircraft at the time had the bare minimum time on type and weren't ripping the wings off the aircraft, just my oppinion but the Spitfire was not famed for being an aircraft 'only experts' could fly.....quite the opposite in fact.

It is of course no problem to fly the Spitfire, with it's quirks, safely, especially when you have the tactile feedback that we are missing in game.
But that doesn't change the facts that only about 19mm stick travel were needed to pull 3 g, and that the stick had to be released immediatly after to hold 3g and not further increase the g-load.
For the ailerons instead a much larger stick travel was needed to gain similar results.
The missing harmony must be reflected in game, regardless about that, that many will be gaming the game and correct the joystick profiles accordingly.

[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:

[6S.Manu]

Originally Posted by taildraggernut

It's Ok to have an oppinnion, my oppinion is that the stability was not a problem given the actual pilots who were flying the aircraft at the time had the bare minimum time on type and weren't ripping the wings off the aircraft, just my oppinion but the Spitfire was not famed for being an aircraft 'only experts' could fly.....quite the opposite in fact.

I've not said it could be only flown by experts: I'm saying that only experts could fly it at its limits. It was a easy plane to fly below those limits.

As this is true for any plane, IMO it's easier to gain confidence in a plane who actually doesn't allow you to fly it in a wrong way than a plane who does not put limits to the pilot's input.

But involuntary spins actually happened, and some pilots were so afraid of it that they could not outturn a 109 flown by a RAF pilot (enough confident in his new ride but, imo, not as the pilots who were flying it all the time).

Towards D-Day

The Norwegian squadrons continued their operations over the channel and into France. Covering American or British bombers on their way to targets on the continent were one of their jobs. Sometimes they were on offensive patrols over France or the channel trying to get the Germans up in the air to fight. Other times they were flying low offensive sweeps into France. The youngest pilot of them all, Marius Eriksen, barely 19 years old of age got shot down when he tried a head-on attack on a FW190. He survived and was taken prisoner. His best friend Jan Eirik Løfsgaard is not so lucky and is shot down when Marius is on leave in London. Other casualties included Captain Stein Sem.

-We dived side by side heading for the coast of France. Just before reaching the coast a FW190 appeared just over and behind Sem’s plane. I called out to him over the radio but it was too late. Black smoke came out from his engine. I heard him calling to me over the radio but I couldn’t hear what he said. I last saw him breaking hard right and upwards with thick black smoke still coming out. I pulled up and to the left but the plane got into a spin and the engine stopped. I couldn’t get the plane out of the spin and knew I had to jump out. I couldn’t get the canopy open and thought I was over and done with. At 4000 feet the plane flatted out and I continued over the channel before the engine stopped again and glycol streamed out. I finally got the hood open enough to get out but the release handle hit me in my face and I had to get out by pulling myself up and kicking the stick hard enough so I would get free. Covered in blood and oil I had a hell of a time finding the parachute opener but found it after awhile and the chute opened at 300 feet. I got into my dingy and after half an hour I was picked up by a British fishing boat. – Pilot Officer Malm.

[lane]

Originally Posted by winny

Like I said before... Now all we need is for some data for the actual in game aircraft, instead of a MK I that is too early and a MK V which is too late...

You do have a point there winny...

[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.