What is "aircraft stability" - IN VIDEO

[klem]

Originally Posted by Crumpp

Exactly. It must be controlled at all times and the pilot must watch his accelerations as he can overload the airframe much easier than other aircraft.

You can see the RAE measurements do not match the game in the most basic of stability characteristics.

The RAE measurements where chosen to be reproduced because of there can be no argument.

A small group of players felt like constantly attacking the NACA data as it was not gathered by the RAE. It was decided to concentrate on reproducing the RAE measurements.

The RAE measured the stability characteristics stick free by recording the oscillation over several minutes.

If you break it down into smaller time elements, you can see the Spitfire is rapidly changing speeds over just a few seconds.

Those oscillations must be controlled by pilot input and as the airplane is not stable, they must be constantly managed.

It is not a stick setting issue but one of the basic flying qualities of the aircraft. Joystick parameters have no effect on it.

Here is what the RAE measured:



Here is the results, the aircraft is neutral or unstable dynamically stick free.



Here is the result of the ingame testing. The conditions are the same. The stability is recorded stick free at 5.46 minutes. At that point the airplane is both static and dynamically stable, something the real aircraft was not during the Battle of Britain.







Never flew a Spitfire without an inertial elevator. In otherwords, he describes the aircraft AFTER the longitudinal instability was fixed.

I don't want to get dragged into this but as its my chart that's being used, two things to observe:

1. It was a quick test which I would like to see others repeat although I did go to great lengths to ensure I was trimmed as stable as possible hands-off.
2. It isn't really stick-free as my stick is held central by the springs, so a 'light hand' on the stick if you like. We can't represent stick-free unless someone has FFB (I know nothing about how FFB sticks would be affected by this). That might do it.

[ACE-OF-ACES]

Originally Posted by klem

2. It isn't really stick-free as my stick is held central by the springs,

Agreed 100%

Originally Posted by klem

so a 'light hand' on the stick if you like.

Depends of the JS.. Some have very stiff spring, some don't. Just too many variations to say one way or another.

Originally Posted by klem

We can't represent stick-free unless someone has FFB (I know nothing about how FFB sticks would be affected by this). That might do it.

Maybe.. But there are variations even in FFB stick.. For example, the Microsoft FFB2, when you take your hand off the stick, the FFB is disabled, where as others will simulate springs and pull the stick back towards center.

In summary, apparently Crumpp has not thought this one through all the way.. There is limitations in the PC simulating a plane.. Flying qualities and seat of the pants types of feedback are something we may never obtain with a $1,000 PC and a $50 game. Long story short, no flight simulation ever was, is, or will be real, hence the name 'simulation'. Once Crumpp comes to grips with that simple truth, than and only than will he realize how silly most of his Spitfire simulation arguments are.

[bongodriver]

Even with a FFB stick the game will not recognise the user has taken their hands off the stick and therefore it will still assume it is just being held in whatever position the stick ends up, try it, move a FFB stick without covering the sensor to activate FFB and you can still make inputs, the game will just not simulate stick-free.

[Crumpp]

How about this has already been simulated in one FM and works very well.

It is not that hard to do.

It was a quick test which I would like to see others repeat although I did go to great lengths to ensure I was trimmed as stable as possible hands-off.

I would like to see others repeat it too. It does not take any elaborate set up.

From level flight, pull back and let go. The FM will return to trim speed.....

It is that simple.

Just like the Spitfire in the game is immune to overstress damage, it is statically and dynamically stable.

[ACE-OF-ACES]

Originally Posted by bongodriver

Even with a FFB stick the game will not recognise the user has taken their hands off the stick and therefore it will still assume it is just being held in whatever position the stick ends up, try it, move a FFB stick without covering the sensor to activate FFB and you can still make inputs, the game will just not simulate stick-free.

Agreed.. Sadly, Crumpp is so vested in this 'story', that he will ignore these facts and simply double down on the 'story' and ignore all these facts as if they were never mentioned.

[JtD]

I see Crumpp's posting the phugoids and spirals on the Spitfire again (35th time?). So I'll just repeat what NACA leading WW2 aerodynamics test engineer - all fighter aircraft of the era which were tested displayed instability in the phugoid and spiral mode. Put the R.A.E. chart from the Hurricane testing next to the Spitfires and you'll appreciate the Spitfires stability in these modes.

And Crumpp, before you post it a perceived 36th time, can you please remove your wrong labels? A plane going into stall in the first cycle is not stable.

[Crumpp]

Hurricane testing next to the Spitfires

Absolutely, by careful flying, a skilled Spitfire pilot can match the precision found in a stable aircraft.

That is not the issue.

The issue is the Hurricane does not require such attention to achieve and hold a precise acceleration. The Hurricane is stable.

[JtD]

Originally Posted by Crumpp

Absolutely, by careful flying, a skilled Spitfire pilot can match the precision found in a stable aircraft.

It's stick free behaviour.

[Crumpp]

It's stick free behaviour.

What are you talking about???

The Hurricane abrupt turn as recorded by the NACA is stick fixed. The Spitfire abrupt turn as recorded by the NACA is stick fixed.

The RAE stability measurements for general stability characteristics are stick free.

In both the RAE and NACA measurements, the Spitfire was longitudinally unstable with unacceptable characteristics.

That is why they added the inertial elevator to fix the longitudinal instability.

What is the issue? Why is blatent fact so hard to understand?

All the smoke, mirrors, and baloney put out about "it is normal" and "all fighters of the day" acted like that is pure fantasy.

If there was not a problem, then they would not have fixed anything!!!