4.101 RC - List of fixes

[JtD]

Originally Posted by PE_Tihi

You been testing the thing a bit wrongly

Well, I went by what you wrote, you've repeatedly complained about stability. If you don't mean stability at all, your fault. Don't blame me. Anyway, looking at how you dodge anything that involves fact, let me sum it up for you:

- the Spitfires stability is realistic
- the Spitfires stability is in the same league as that of many other planes in game

And now it's the hammerhead which is so awfully wrong. What exactly does a vertical zoom climb with rudder input at 100 km/h in a Fw 190 look like? Or in a P-38? Or a P-39? Wait, they all go up, then out of control. And because the planes are different, they go out of control differently. Holy cow.

Which aerodynamic forces do you think should keep the plane controllable at 0 air speed?

[PE_Tihi]

Originally Posted by JtD

Well, I went by what you wrote, you've repeatedly complained about stability. If you don't mean stability at all, your fault. Don't blame me. Anyway, looking at how you dodge anything that involves fact, let me sum it up for you:

- the Spitfires stability is realistic
- the Spitfires stability is in the same league as that of many other planes in game

And now it's the hammerhead which is so awfully wrong. What exactly does a vertical zoom climb with rudder input at 100 km/h in a Fw 190 look like? Or in a P-38? Or a P-39? Wait, they all go up, then out of control. And because the planes are different, they go out of control differently. Holy cow.

Which aerodynamic forces do you think should keep the plane controllable at 0 air speed?

If a plane has a low 'reserve' of stabillity, it is in the very slow flight that this deficit shows in a most pronounced manner. Thats where you would ve got the best chance of noticing it; of course if you do not want or cannot, that s another matter.

All other planes including the ones you name can be helped with a kick on the rudder to drop their noses shortly before the steeply climbing plane stalls. It can be done without reducing power.
Spit enters shortly before the stall speed a zone of completely neutral stability, where there is no natural tendency to drop the nose which could be helped. Gyroscopic forces keep the nose pointing upwards, and the controls can do nothing about it. You ll have to cut power if you want the nose to drop, and lose further energy in the strong oscillations which, with the pilot helping, still do not diminish before the plane reaches 160-170 kph. By that time you ll be quite a bit underneath a P40, not to speak of a Bf which is really good at stall fight.

Even at higher speeds, in a dogfight (say 350-250 kph), if you press a pedal to move the aiming point ( do you use the rudder for aiming at all?) it causes easily noticeable oscillations, spiced with precession from the rotating prop, which are practically unnoticeable in the old Spit or any other game plane.
The effect is that you sideslipping mostly as you shoot, making the bullets go where they want.
The people flying this game longer mostly use much more rudder than newer pilots, both in maneouvres or when aiming. Even if you shoot at 400 kmh where the damping is better, as you aim, you ll still be sideslipping enough to miss.

1) I do not know whether the Spit stabillity is reallistic in 4.10- and suspect not. You know it, good for you.
2) I certainly know your second sentence is not true.

If you cannot fly a hammerhead, you have one recipe here. And if you don't want to find out something, but only to prove yourself smart, you can do that without my involvement, either.

[IceFire]

Originally Posted by JtD

Well, I went by what you wrote, you've repeatedly complained about stability. If you don't mean stability at all, your fault. Don't blame me. Anyway, looking at how you dodge anything that involves fact, let me sum it up for you:

- the Spitfires stability is realistic
- the Spitfires stability is in the same league as that of many other planes in game

And now it's the hammerhead which is so awfully wrong. What exactly does a vertical zoom climb with rudder input at 100 km/h in a Fw 190 look like? Or in a P-38? Or a P-39? Wait, they all go up, then out of control. And because the planes are different, they go out of control differently. Holy cow.

Which aerodynamic forces do you think should keep the plane controllable at 0 air speed?

Sorry for wading in

Most people don't seem to be able to articulate what they are seeing. So I'll give it a try.

It took me a while to notice but eventually I did. Now that I've noticed... I can tell that the Spitfire is definitely a slightly more challenging ride than before. Before it felt a bit like it was on rails in some cases. Now it does have some "extra character to it". I can't say if it's right, wrong or different. So far the best way for me to test to see the difference is to snap roll 90 degrees left and right and then return to level flight.

It seems the aileron movements causes the extra yaw. I'm fairly certain this is called adverse yaw. It is slightly more severe than on many other types (by my approximation) although I can also list several types that have it more extreme than the Spitfire as well.

I do know that stability changed between the different Spitfire models and the redesigned tail for the later IX models represented an attempt at correcting some stability issues introduced by the Merlin 60 series installed up front which changed the length, weight distribution and relative stability of the model. I don't have the numbers... just the general details so unfortunately I cannot be more specific.

The revised modeling does seem to be across the board but it may be worthwhile to double check Mark V versus early Mark IX versus late IX (and VIII) just to be certain that values are what they should be?

Just some thoughts.

EDIT: Those of you having more difficulties with this may want to adjust their joystick curves to slightly reduce the sensitivity. Particularly on the rudder. That should help... along with a proper rudder coordination technique to work with excess yaw. Particularly during gunnery.

[Blackdog_kt]

Originally Posted by IceFire

Sorry for wading in

Most people don't seem to be able to articulate what they are seeing. So I'll give it a try.

It took me a while to notice but eventually I did. Now that I've noticed... I can tell that the Spitfire is definitely a slightly more challenging ride than before. Before it felt a bit like it was on rails in some cases. Now it does have some "extra character to it". I can't say if it's right, wrong or different. So far the best way for me to test to see the difference is to snap roll 90 degrees left and right and then return to level flight.

It seems the aileron movements causes the extra yaw. I'm fairly certain this is called adverse yaw. It is slightly more severe than on many other types (by my approximation) although I can also list several types that have it more extreme than the Spitfire as well.

I do know that stability changed between the different Spitfire models and the redesigned tail for the later IX models represented an attempt at correcting some stability issues introduced by the Merlin 60 series installed up front which changed the length, weight distribution and relative stability of the model. I don't have the numbers... just the general details so unfortunately I cannot be more specific.

The revised modeling does seem to be across the board but it may be worthwhile to double check Mark V versus early Mark IX versus late IX (and VIII) just to be certain that values are what they should be?

Just some thoughts.

EDIT: Those of you having more difficulties with this may want to adjust their joystick curves to slightly reduce the sensitivity. Particularly on the rudder. That should help... along with a proper rudder coordination technique to work with excess yaw. Particularly during gunnery.

You might be on to something here.

Adverse yaw is encountered in all aircraft, but maybe the Spitfire's famous wing is partially to blame in this case?

From the wiki:

According to the diagram, when the control column of an aircraft is moved to the right, the right aileron is deflected upwards, and the left aileron is deflected downwards, causing the aircraft to roll to the right. As the right wing descends, its lift vector, which is perpendicular to the relative motion, tilts forward and therefore has a forward component. Conversely, as the left wing moves up, its lift vector tilts back and therefore has an aft force component. The fore/aft lift force components on the right and left wings constitute the adverse yaw moment.

Why do we care? Well, because more lift means a bigger forward/backward component in the diagram, which means more adverse yaw. If the Spitfire's wing is capable of higher lift than other aircraft (for a given airspeed range, conditions, etc etc) then it will also be prone to more adverse yaw, which means you need to use the rudder more or have oscillations when it goes back to neutral behavior.

I don't know exactly how the Spit's wing compares to other aircraft, so if anyone could shed some light maybe we could track down if this is the cause of the instability. In the case that the Spit wing is better at producing lift then incurring extra instability during rolls would be accurate. There's no such thing as a free lunch in physics


On a more humorous note

Originally Posted by Brain32

Thrust vectoring? xD

Good one

[JtD]

The Spitfire has a CoG that's somewhat rearward. A bit more than on most other planes. This means that any force input will give you a larger effect - be it control input, adverse yaw or even gyroscopic effects. It also gives the plane a considerable nose up tendency.

That's all there is to it.

[ImpalerNL]

The spitfire was very light on the controls, especially the elevator.
Also the tail was very light when taxiing and during takeoff.

You can read it here.

http://www.paulsquires.co.uk/spitfire.html

http://www.vintagewings.ca/VintageNe...ke-Potter.aspx

I like this sentence from the vintagewings article:

And, like all fighters of this era, you need your two feet as well as your hands to fly or she will skid and slip all over the sky.

[AndyJWest]

...the tail was very light when taxiing and during takeoff.

I can vouch for Oleg getting that right then. I think I must have tipped a Spit onto its nose so many times that in real life I'd have been demoted to potato-peeling duties long ago. Of course, in real life you could get an erk or two to sit on the tail while you taxied - I wonder if CoD will model this...

[PE_Tihi]

Originally Posted by JtD

The Spitfire has a CoG that's somewhat rearward. A bit more than on most other planes. This means that any force input will give you a larger effect - be it control input, adverse yaw or even gyroscopic effects. It also gives the plane a considerable nose up tendency.

That's all there is to it.

The longitudinal (pitch) stability you are describing here, has nothing to do with the adverse yaw- which is a yaw problem, obviously.

It is quite clear DT, among other things moved the CG position backwards. That this brought a big change in the plane's trim is no big credit to them. The horizontal tail of any plane is designed so that it's negative angle of attack produces exact amount of downwards lift to compensate the nose down moment the main wing lift produces in the cruising flight.

Take a look at the picture below. A plane always rotates around the CG - imagine it fixed in space.

A plane with a normal load requires only a little or no pitch trim in a cruise. Much trimming is necessary at quite low or high speeds.
A strongly trimmed elevator has more trim drag, that s why no factory ever delivered such a plane DT did. The elevator AoA corresponds to a certain CG position. That is one reason why I doubt their FM.

If they changed Oleg's CG, they should 've changed the elevator AoA too, to minimize the trim drag.
Now I should trust their stability rendering, which is a more complicated issue by far?

CG position of the Spit isn't something one has to guess-am sure anyone googles it out in 5 minutes. DT discovering here something unknown to Oleg doesn't sound very probable to me.

I can well imagine stability of the Spit and all other planes having been made easier at the game's beginnings, for rather obvious reasons-everyone still being new to a game already prohibitively challenging for many, etc. I doubt Oleg touched the CG position very much; increasing the damping factor instead sounds much more logical. DT ll learn fast, I suppose, but until they have learnt, the game may be over.

And that's it.

[Fenrir]

Originally Posted by Blackdog_kt

You might be on to something here.

Adverse yaw is encountered in all aircraft, but maybe the Spitfire's famous wing is partially to blame in this case...

Why do we care? Well, because more lift means a bigger forward/backward component in the diagram, which means more adverse yaw. If the Spitfire's wing is capable of higher lift than other aircraft (for a given airspeed range, conditions, etc etc) then it will also be prone to more adverse yaw, which means you need to use the rudder more or have oscillations when it goes back to neutral behavior.

I don't know exactly how the Spit's wing compares to other aircraft, so if anyone could shed some light maybe we could track down if this is the cause of the instability. In the case that the Spit wing is better at producing lift then incurring extra instability during rolls would be accurate. There's no such thing as a free lunch in physics.

The Spitfire had Frise ailerons. These are designed so that the aileron on the lower wing in the turn pokes it's nose into the airflow and creates drag, thus to some extent compensating for adverse yaw.

How much tho is another question entirely....

[PE_Tihi]

Originally Posted by Blackdog_kt

You might be on to something here.

Adverse yaw is encountered in all aircraft, but maybe the Spitfire's famous wing is partially to blame in this case?

From the wiki:



Why do we care? Well, because more lift means a bigger forward/backward component in the diagram, which means more adverse yaw. If the Spitfire's wing is capable of higher lift than other aircraft (for a given airspeed range, conditions, etc etc) then it will also be prone to more adverse yaw, which means you need to use the rudder more or have oscillations when it goes back to neutral behavior.

I don't know exactly how the Spit's wing compares to other aircraft, so if anyone could shed some light maybe we could track down if this is the cause of the instability. In the case that the Spit wing is better at producing lift then incurring extra instability during rolls would be accurate. There's no such thing as a free lunch in physics


On a more humorous note



Good one

Spitfire wing produces a lift equal to the plane's weight in horizontal flight. Maximum lift is produced in sharp turns; the plane's great wing area with the accompanying lift producing capacity does not make for any increases of adverse jaw effect in low-G regimes. On the other hand, as you can see from your diagram, a plane with a bigger wingspan (and aspect ratio) does have the best chances for an increased adverse yaw because of a longer moment arm of the ailerons/wing outer panels relative to the CG/aircraft axis. Gliders and Ta 152H, for example, come into that category.

The Spitfire had differential Frise ailerons- that means most effective means available to counter the adverse jaw. Frise has a price of increasing the rolling plane's drag, but Mitchell obviously accepted this trade-off knowing that a fighter has to hit something, too.

Spitfire wings were an excellent and beautiful design, but that ellipse is not such a magic as it's fame implies. It was a quite thin profile, large area and low wing loading that did much more for the efficiency of it's wing's then their elegant elliptical planform, which probably did more for the Spit's high unit price.
Twisting the tips of a conventional tapered wing-planform brings it very near to the optimal elliptical lift-distribution*, at a fraction of the cost of a wing with an actually elliptic geometry. This goes even for the squared-off wingtip planforms, which do not spoil the lift distribution much additionaly, either (Bf109, P51).
Mitchell knew that very well, for sure, but went over to the elliptical wing after additional guns have been demanded - and he had no room for them in the original tapered wing. Moreover, the ellipse solved the structural problems of a thin profile and made his already excellent wing concept a couple of additional percent better aerodynamically; I imagine nobody asked much about the unit price at that time, anyway.

Rarely used for the reasons mentioned, the elegant ellipse of the wings made the Spit recognizably different from the other planes, and the chance to create a bit of magic around this has not been missed in a wartime, of course.
This famed ellipse of the Spitfire's wing found a way into the British hearts so deep, that redesigning the Typhoon into Tempest, Camm took the semi-elliptical planform partly to inspire confidence of his customers in the ministry, I suspect.

Nothing occurs to me as a possible cause for any increased adverse yaw in the spit's wing aerodynamic.
Like almost all fighters, Spit has had a lean stability for the sake of being more manoeuverable. Many pylon racers of the period were much more radical in that sense. Polikarpov designs, especialy the I16 had quite narrow stabillity margins, almost like racers.

Adverse yaw is only one of the disturbances (like gusts, gyroscopic effects, etc) which the stabilizing surfaces have to overcome, and the gyroscopic precession after a pedal has been kicked should be more noticeable on any prop plane than the adverse yaw.
Real Spit probably felt the adverse yaw properly only when rolling quite fast. So, you barking under a wrong tree, my lads


* When the lift-force distribution along the wingspan has a shape of an semi-ellipse, it s an optimal case, with the lowest induced drag, i.e highest lift-producing efficiency.