Why still no dive acceleration difference?

[FC99]

Originally Posted by mayshine

FC99 do you know the drag formular?

I am working on it and found some problem in the speed.

I shall propose the result after double check


the formular is

Drag force (air friction to plane itself)

Drag= air drag coefficient*0.5*air density*air speed^2*wing demension

air drag coefficient should be the result from the lab and in Il2 data

can you just use the digit provided in Il2 software data?

coz your team are easier to dig out the date encoded

and see the difference in my simplified model between planes

(m*g-drag)/m

FWA5 0,0236
La5 0,025

Why don't you just work backwards and calculate how much different planes should be for separation after dive to meet your expectations.
BTW how big the difference should be in your opinion after 2000m vertical dive?

Originally Posted by BlackBerry

The heavier a/c is, the more ability of retaining high speed which is above a/c's maximum level speed.

If everything else is equal.

In P51-zeke's test, they just did a shallow dive and then zoomed up. The zoom's beginning speed must be lower than 325PMH IAS.


At first, they zoomed up from cruising speed,that was 210MPH IAS=250MPH TAS, when P51d reach 130MPH=150MPH TAS, zeke was 90m lower. So how much kinetic energy was spent to get altitude?

0.5(250^2-150^2)= 20000

If they begin from 325MPH IAS=389MPH TAS

0.5(389^2-150^2)= 64410

We assume that there is a linear relationship between "kinetic energy" and P51D's zoom advantge to "damaged" zeke52.

So this time, p51d should be 3.22*90=290metres higher.


That is to say, when p51d @325MPH IAS@10000ft, and find a (lightly damaged) zeke on his 6 with same altitude and speed. And the distant between them are 450 metres. P51D may try a zoom, and will probably (450+290)=740m higher than zeke when p51d's speed drops to130 MPH IAS.

Surely 740m is enough for avioding being hit by zeke's cannon.

Distance between them will not be converted into altitude and if P-51 zoom at 90deg up as you suggested previously A6M5 will just cut the corner, use more energy efficient maneuver , close the distance to P-51 and in the end it will have nice fat P-51 close and slow right in its gunsight.

Happens online all the time.

Perhaps, p51d will gain sth.300meters advantage over 109 by starting a high speed (450MPH IAS)zoom, who knows? You can not simply deny that possibility.

Maybe, maybe not. Anyway, question is not about couple hundreds meters, it's obvious that some expects lot more than that. When you are slow on top of the zoom and enemy is 300 m behind you you are dead meat, more often than not and when that happens, it's not the problem with the game physics, it's pilot's error, as simple as that.

[K_Freddie]

It has been known for years that the game accelleration rates are not that accurate. I think the documents from which the games rates are taken are from shallow test dives (as mentioned) so cannot really be extrapolated to 90 degree dives.

In this situation, there probably should be large initial differences due to weight, power and friction, as this was guaranteed escape tactic for the FW, P47 and others, against the lighter aircraft. Maybe TD can tweak the FM's in this area.

[FC99]

Originally Posted by K_Freddie

It has been known for years that the game accelleration rates are not that accurate. I think the documents from which the games rates are taken are from shallow test dives (as mentioned) so cannot really be extrapolated to 90 degree dives.

Acceleration rate in dive is product of thrust, gravity and drag. Same equations are used no matter the plane attitude. Gravity is the same in the game no matter what the plane is doing. Thrust and drag are inside reasonable margins under level flights and climbs so there is no reason to believe that they are wrong during dive, especially during the initial phase.

Maybe TD can tweak the FM's in this area.

We could but we prefer to have FM as realistic as possible.

[K_Freddie]

The final test would be P47-vs-something else.

We all know that the p47 'dropped like a brick'... if this doesn't happen in comparison to other a/c... we quiet simply have a FM problem .. period!


This is a valid, if not 'niche' point brought up by mayshine.. whether anybody likes it or not, is irrelevant.
and..
Yes Yes.. we've done the aeronautics and formulae ad-nauseum

[K_Freddie]

Thrust and drag are inside reasonable margins under level flights and climbs so there is no reason to believe that they are wrong during dive, especially during the initial phase.

Interesting.... and you actually believe this statement to be the 'absolute truth'

It is time to rethink FM policy...

[AndyJWest]

It is time to rethink FM policy...

Based on guesswork, or data?

[JtD]

Originally Posted by K_Freddie

We all know that the p47 'dropped like a brick'...

Actually, it's not "we all know", but "some think". I know that it dropped faster than a brick, and it does in game. A brick neither produces the thrust a P-47 produces, nor is it anywhere near as aerodynamic. However, this applies to about all WW2 fighter aircraft.

Anyway, you are more than welcome to do the research, dig up a few tests and take it from there.

[FC99]

Originally Posted by K_Freddie

The final test would be P47-vs-something else.

We all know that the p47 'dropped like a brick'... if this doesn't happen in comparison to other a/c... we quiet simply have a FM problem .. period!


This is a valid, if not 'niche' point brought up by mayshine.. whether anybody likes it or not, is irrelevant.
and..
Yes Yes.. we've done the aeronautics and formulae ad-nauseum

Mayshine's question has been answered, dive acceleration difference exist in game already.

And P-47 falls like the brick in comparison with most other aircrafts.

Originally Posted by BlackBerry

I have a question, does bf109g6as outdive spitfire IX or fw190A8 during the initial phase in 4.11m?

Depending on initial conditions and your definition of "initial phase" that's probably possible.

FM data you posted for several planes looks like 4.11 data.

Originally Posted by Crumpp

Tell me you don't touch any of the flight models.....

Excess thrust......not the same!

And JtD is wrong in what exactly? AFAIK F=mg, g is a constant and is the same for every object in game.

[Crumpp]

And JtD is wrong in what exactly? AFAIK F=mg, g is a constant and is the same for every object in game.

Of course it is Fatcat. This is not the issue and completely irrelevant as to why your FM's would not exhibit any differences in dive acceleration. It does not answer the original poster's question.

Take the force triangle for a dive. A component of weight contributes to thrust based on the angle of dive. The difference between the force on the axis of motion in the dive and the force on the axis of motion for level flight is your initial excess force that will move the aircraft to its new equilibrium point velocity. The derivative between that and equilibrium is your average excess force along that vector....

Then apply the same formula...

Force = Mass x Acceleration

Rearrange it to solve for Acceleration: The acceleration of gravity is considered constant but acceleration is not constant.

Acceleration = Force/Mass

You then have the aircrafts acceleration rate to the equilibrium point.

Now I am not a computer programmer but I am sure there is a way to look at the code to see if it following those principles.

[JtD]

Originally Posted by Crumpp

It does not answer the original poster's question.

But it does. The original poster asked in the topics title why there are no dive acceleration differences. There aren't because gravity is the same for all planes. As soon as you consider anything else, the dive accelerations are different. Had he asked why all the dive accelerations are different, the question would have required a much more complex answer.
The answer was specifically given to the question asked.