True Altitude?

[Soldier_Fortune]

Hi again!

Your remarks are right: at low speeds the difference between EAS and IAS is negligible.
For TAS close to the sound speed the equation is quite different and a bit more complex.
Always you can check your TAS calculations with the in-game TAS for a given map and any altitude, flying a Me-262 or a B-25J.

[Jeremiah_Weed]

Just FYI.............
After some more thought, I realized that bomb flight paths could be manipulated during flight between aircraft and target, and any manipulation could therefore remain unnoticed. I realized that rather than having several planes try to drop at the same time, just use a stopwatch and time the drop from plane to target from altitude. Any falling object, so long as no other force like drag or thrust is acting on it, will follow set rules...rules set by classical mechanics.

I dropped several bombs from altitude and the results were interesting. For instance, a 1000kg bomb (with zero delay) dropped from an IL-4 at 7650 meters took 41.77 seconds to impact. It should have only taken 39.49 seconds. Another drop from the same plane with the same bomb, but at 7850 meters, took 42.38 seconds to impact. It should have only taken 40.01 seconds. Other drops from other aircraft using different types of bombs resulted in very similar results. All time-of-flights from this altitude took 2+ seconds longer than would be expected.

Other drops from other planes at lower altitudes achieved similar results, with all drops taking longer than expected. A drop from a Ju88 at 4820m took 32.74 seconds and it should have only taken 31.35 seconds. A drop from a B5N2 at 4950m took 32.58 seconds and it should have only taken 31.77 seconds. Another drop from a B5N2 from 4890m took 32.39 seconds and it should have only taken 31.57 seconds.

Conclusion: YES...flight paths from bombs ARE being manipulated in IL-2 and are NOT following the rules of classical mechanics.

[KG26_Alpha]

What I tested seems correct then JW

ok.........

I found this not sure how applicable/correct it is and might explain what TD have done.

"v= v(initial) + at works in a vacuum in which WWII bomber did not fly. v=obviously velocity. a= acceleration

D= 1/2 CpAv^2 Where C=Drag Coefficient, p= rho=air density, A=crossectional area v= obviously velocity.

However at some some value of v Drag will equal mg this point is called terminal velocity. m=mass, g=gravity

so, 1/2CpAv^2 = mg

v= (2mg/CpA)^(-1/2)

This is only a rough formula to calculate the terminal velocity of the bomb because aerodynamics get very complicated, but this should get you somewhat close.
All you need is the mass of the object, gravity which is 9.8 m/s^2, the drag coefficient,
air density at the point that you want to know presumably fairly close to sea level, and the cross sectional area."


Might be rubbish.............


Chart monkeys apply within





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[Soldier_Fortune]

Originally Posted by KG26_Alpha

What I tested seems correct then JW

ok.........

I found this not sure how applicable/correct it is and might explain what TD have done.
...
Might be rubbish.............

Hi KG.

That equations are interesting. But as far I could see, drag is not included into the bombs' FM.

I've tested all sort of bombs (German, Russian, Japanese and American) in my level bombing tests, with masses ranging from 60 up to 2000 kg; and I didn't see drag effects.

Basically the manual targeting is a BS Elevation Angle calculation using the classical equations for parabolic motion, and utimately that depends of the falling time. If there would be a different drag effect for every bomb's weight and shape (like it is IRL), such BS Elevation Angle should be dependent of the bomb type, and therefore it would be different for each one. But it is not the case.
And, of course, I used the classical equations for parabolic motion you've posted several posts above.

What I observed is the wind effect over the free fall weapons. But all bombs are affected in same way. And this should be sufficient to guess that we've a simple and newtonian FM for all bombs in IL-2, with the crosswind component (when it exists) as the only force vectorially combined with vertical and horizontal velocities acting on a bomb, and determining its path.

[KG26_Alpha]

That does not explain the inconsistency with bombs falling long or short when the correct inputs are made into the bombsites.

Whats is consistent is the above happening on all maps at different OAT's alts and speeds, the Russian bombs fall long and the German fall short.

This can only mean that there is a different non real world calculation for the bombs in IL2 1946.





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[Soldier_Fortune]

Originally Posted by KG26_Alpha

That does not explain the inconsistency with bombs falling long or short when the correct inputs are made into the bombsites.

Whats is consistent is the above happening on all maps at different OAT's alts and speeds, the Russian bombs fall long and the German fall short.

This can only mean that there is a different non real world calculation for the bombs in IL2 1946.

Wrong.

That only means the bombsites now are uncalibrated and don't work as they are intended for automatic targeting and drop, like if you were playing with an uncalibrated joystick or any other device: your inputs may be correct, but the outputs are not those you know since long time ago.
Therefore, if you can't fix the problem, you'll must use any other device to play (the keyboard, i.e.), changing analog, smooth and easy inputs by proportional amounts of keystrokes.

"Russian bombs fall long and the German fall short"... What about American, Italian and Japanese bombs? How do they fall?
Have you tested them already?
I did do it. And I didn't see any "non real world calculations" about bombs in any case.

Do you like to get good hits while level bombing? Then (by now, at least), give the bombsights the right outputs from your own calculations, and use manual targeting, because Norden/Lofte and OKPB-1 bombsights are unable to do it by themselves.
Thus, whether you prefere to believe it or not, we need no "esoteric formulas" to play with this sim.

[Jeremiah_Weed]

Soldier_Fortune
With regards to using the game's internal clock, yes, you are absolutely 100% correct with that. I couldn't agree more. In fact, I had thought of doing that. My keyboard, a logitech G105, has several keys which are programmable and will allow macros to be preprogrammed to include several keystrokes. Also, the games internal clock, which can be accessed with the console command, >tod, reads out to 6 places which is 3.6 milliseconds...MORE than accurate enough to run the test. My thought was to program a macro key which drops the bomb, pauses the game, and then accesses the >tod command in one keystroke, then, program another to pause the game and access the >tod command when the bomb impacts. As time permits this weekend (I'm at work now) I'll set that up and run some trials. I'll also post the results.

Also, with regards to your equation. I agree that it would calculate the correct TAS for this type of aircraft and those types that operate in the flight envelope common for this type of aircraft. (There are several formulas for specific flight envelopes; high-subsonic, trans-sonic, supersonic, etc., and for those aircraft with high compressibility) But I don't think it would generate the correct figure to use on bombsight TAS for all aircraft across the board. Russian planes, like the Pe-8, TB-7, IL-4, and the SB 1M, require a higher value than actual TAS and bombs fall long if this higher value is not used. Also, other planes like the Ju 88, the He-111 H-2, the SM.79, require a lower number than actual TAS and bombs fall short if the lower value isn't used. That's why I was including a "velocity factor" to compensate.

Well, duty calls...so back to work.

[Soldier_Fortune]

Originally Posted by Jeremiah_Weed

...
Conclusion: YES...flight paths from bombs ARE being manipulated in IL-2 and are NOT following the rules of classical mechanics.

Hi J_W!

May be you have discovered a more elemental game's feature: the in-game's time would pass more slowly than IRL.

Don't worry: this has nothing to do with Stephen Hawking or the Theory of the Relativity.

But there would be some practical reasons for such delay.
In any case, we should apply the following basic rules of thumb:

- Never use other than a sim's in-game clock to measure their internal times.
- Never use other than a sim's in-game ruler to measure their internal distances.
- Never use other than a sim's in-game protractor to measure their internal angles.
- Never use other than a sim's in-game guages to measure their internal magnitudes and quantities.

Because a sim is an approximate model of a part of Reality, but it is not Reality.

In order to the above, before making a jugdment about whether the bombs' flight path are being internally manipulated or not, we should check if the game's clocks are sinchronized with those of the real world or not.

The delays you've observed are +6% over the calculated theoretical time, and that percentage remains almost constant regardless of the altitude.
That means adding 0.06 s (or 60 ms) every elapsed second. It's like as if an in-game electromagnetic wave of 60 Hz was seen as a wave of 13 Hz IRL.
And the same could be applied to every physical magnitude within the sim... if the developers have decided to apply it.

It is easier to establish an intencional delay (for whatever technical reason), than to introduce specific constants which in turn depend of certain conditions. The last demands many more calculations and resources, and it's more difficult to tune: this would be the case for such "bombs' path manipulation".
But the time must be the same for each "universe", and it would be easier to handle for a "fine tunning of the IL-2 universe" by their developers.

I would like to do an experiment about your data, but I can't come home yet. Thus I'll beg you to do the following test, please:

1) Design any bomb mission, and place a static camera near to the target.

2) You must use the onboard clock (instead an external stop watch) to measure the time it takes for the bomb to hit the ground (the He-111 would be a good choice: this aircraft has a clock just in front on the player offering them a complete and clear view of it. This clock counts seconds).

3) Play the mission. Drop your bomb when you're ready, and immediately pause the game.

4) Read the drop instant with the aircraft's clock, and hit the "camera view", and gather all the in-flight data with the gauges (not the speedbar): altitude, IAS, OATs, variometer, how much elevator trim is applied if the autolevel is engaged.

5) Unpause the game and be ready to pause the game again when the bomb hits the ground.

6) Jump to the cockpit and read the clock again.

7) The difference between the two readings is the bomb's flying time within the IL2 universe.

With the onboard clock you cannot measure times shorter than 1 second; but it should be sufficient to measure differences of 2 seconds.

Other experiment might be to measure a longer lapse (i.e.: 2 or 3 minutes) simultneously with both the aircraft clock and your stop watch, to see how long is that "IL2 universe" lapse when it is compared with the RL.

It's not relevant if that time matches or not the RL time, while all the other variables are consistent with that. If that consistency was verified, the Mechanical Laws would remain applicable within IL2.

But if not... Then I should review all my calculations to find why the laws of Classical Mechanics seems to work well for manual targeting.

Please: if you carry on such experiment, let me know your data, outcomes and what map you've used.