True Altitude?

[Soldier_Fortune]

These are questions mainly adressed to the TD.

Since the patch 4.11, we are noticed that each map has a Ground Level temperature. The published Temp_Guide_4111 provides hints for a right management of the engines avoiding overheatings.

But also I've seen in-game that the GL temperature, indicated for each map, decreases in steps of -6.5 ºC each +1000 m ASL (or -2 ºC each +1000 ft ASL) as it is IRL, and it affects the TAS: in a winter map, at a given altitude, the TAS is slower than the TAS in a summer map, for the same altitude and the same plane.

IRL the free air temperature also determines the True Altitude similarly to the TAS: in a colder map a plane flies a bit lower than the Indicated Altitude read in the altiemeters, and in a hotter map the same plane would fly a bit higher than the Indicated Altitude.

Since both variables TAS and Altitude are used to adjust the bombsight, I would like to ask you:

1) Is the True Altitude a variable included in the FM?

2) Should we use this True Altitude as a setting for the bombsight?

3) Or should we use the Indicated Altitude as ever?

Thank you. :cool:

[KG26_Alpha]

If the air density has been changed in v4.11 then perhaps the bombs are affected giving the long drop syndrome were seeing since the patch.


A recalculated table would be needed for the game.


But the standard real world calculation should apply.






.

[Soldier_Fortune]

If the air density has been changed in v4.11 then perhaps the bombs are affected giving the long drop syndrome were seeing since the patch.


A recalculated table would be needed for the game.


But the standard real world calculation should apply.



In one hand, the IAS/TAS charts and tables made by some players several years ago (before the patch 4.11 was released), now are totally useless because the simplified model of the air included in the game considered a constant free air temperature = 0ºC at any altitude for all maps.

In the other hand, we would need an IAS/TAS chart for each map, since the most of them have different Ground Level temperatures (GLT), being this GLT the starting point for any calculation about TAS... but that would be a too hard work for anyone. Perhaps the interested players should have their own E6-B flight computer, but perhaps not all the interested players would afford 10 or 12 U$D for the cheapest models.

With 'no wind' TAS depends of the altitude and the free air temperature, and this data is used as a setting for the bombsight. As far as I tested, the free fall bombs are not affected by the air density in a different way than the aircrafts and, if you use the right TAS, your bombs should hit the selected targets.

But if in your mission the designer has included any wind, this adds a new problem since the TAS and the Ground Speed (GS) has not the same value, being this GS the parameter needed for to set the bombsight up, and not the TAS (before the patch 4.10 the TAS was the velocity for the bombsight because when wind_speed = 0, then GS = TAS).

This problem may be solved again with an E6-B computer in the simplest fashion, being the other ways (involving several manual calculations each time) too complex and too boring for the most of the players.

In any case, this affects almost all what we've learned and known about level bombing up to the patch 4.09.

But the standard real world calculation should apply.

I'm agreed with you.
Now I know the effect of the wind, the altitude and the free air temperature on the TAS and the GS, how to calculate them in an easy, funny and realistic/historical fashion, and how to use them into the sim.

But also I need to know if the True Altitude (regarding of the free air temperature) has been modeled and if it should be used instead of the Indicated Altitude for to calibrate the bombsights.

[KG26_Alpha]

The bombsite tables I have posted are from the original 1C team and came with the game they used to work perfectly well.

Adaptive bombing has been forefront in the game for years, there never really has been a "perfect" solution for non TAS calculation bombsites,
they are more a rough guide to where your aiming, over the years the bombs are no longer as effective as they used to be,
if you were a little long or short, the blast radius seems to have been changed so now you have to almost hit the object directly in incur effective damage.

It makes the human bombers job miserable as there nothing worse than dropping 1000kg of bombs on a target missed by 50 meters only to see nothing destroyed.


From the BBC Blitz Street, it gives an idea of effective blast radius against housing,
transpose that to flat open airfields and the destruction should be greater than what we have now.

http://www.youtube.com/watch?v=L0v2Uq8z7aI

Also

It would be interesting to know exactly whats been done regarding air density.

[Soldier_Fortune]

The bombsite tables I have posted are from the original 1C team and came with the game they used to work perfectly well.



Those bombsite charts, which you have posted in other treath, worked fine before the patch 4.11 was released, because the atmosphere model considered an outside temperature of 0 ºC always, as well as if the map was the Gulf of Finland in winter, as if the map was MTO or Burma. So now, after that patch, those charts became obsolete and useless, and they only mislead the readers.

Let me to explain this with an example:

For an altitude ALT = 5000 m =16,400 ft and for an IAS = 250 km/h = 135 KTS, I'll calculate the TAS. The considered outside temperature is a constant value of 0 ºC.
The result, computed with an E6-B, is: TAS = 180 KTS = 332 km/h.
This computed TAS matches the TAS obtained from the charts.

MAP GULF OF FINLAND (WINTER).
Outside temperature at GL = -20 ºC. According to the IAS (International Atmosphere Standard) the air temperature decreases at -2 ºC/1000 ft ASL. So, at 16,400 ft the outside temperature for this map should be -52.8 ºC.
For the same conditions of IAS and altitude, now TAS = 160 KTS = 297 km/h

MAP MTO
Outside temperature at GL = 28 ºC. So, at 16,400 ft the outside temperature for this map should be -4.8 ºC.
For the same conditions of IAS and altitude, now TAS = 178 KTS = 330 km/h

It's very easy to check if these computed values are true or not, just flying with a Me-262 at those altitudes in both maps, and reading the speed gauge.
And if a computed TAS is true for the Me-262, also it must be true for any aircraft.


Adaptive bombing has been forefront in the game for years, there never really has been a "perfect" solution for non TAS calculation bombsites,
they are more a rough guide to where your aiming, over the years the bombs are no longer as effective as they used to be,
if you were a little long or short, the blast radius seems to have been changed so now you have to almost hit the object directly in incur effective damage.

It makes the human bombers job miserable as there nothing worse than dropping 1000kg of bombs on a target missed by 50 meters only to see nothing destroyed.

First of all, if a player is satisfied using adaptative bombing (or any other tactics), it's all right.
But for myself, I prefer to know where my good luck ends and where my skill begins.
The adaptative bombing is too random for my taste, so I'm working for to improve my skill from a 'scientific' base: this base would give me a good reference to know how is progressing my own skill.

I'm shure it is possible to perform precision bombing from an altitude above 5000 m, if the inputs for the bombsite are correct. A step forward: I think that would be posibble to perform precision bombing over a target completely hidden by clouds or darkness, only with the aid of NDBs. :cool: ... but if the pilot flies taking in account distances, times, altitudes, wind speed, outside temperatures, bearings to the NDBs, true courses, true headings, ground speeds...

From the BBC Blitz Street, it gives an idea of effective blast radius against housing,
transpose that to flat open airfields and the destruction should be greater than what we have now.

It's a very interesting video: thank you for share it with me.:wink:
About the in-game blast radius, I agreed with you: it should be greater. Perhaps the developers decided to reduce the bombs' DM for balance purposes, I don't know. But, as a reference, a Mk-84 bomb (2000 pounds = 900 kg) has a blast raduis of 400 yds (365 m)... and I never saw such destruction with a 1000 kg bomb in this sim.

[KG26_Alpha]

I'm pretty sure ambient temperature, at ground level at least, has been modeled for a long time.

The fact they produced a v4.11 "read me" showing map temps doesn't mean they were not present long before v4.11

Desert maps ambient temps were @ 80-90' back on v4.07 iirc
You only had to look at the temp gauge on your aircraft with the engine off on the runway to see ambient temperature was in the map.
Which was always a bit strange as the engine was cold but the temp gauge registered outside temp.
Air density at altitude is the interesting factor though it seems something had changed.

A word form TD would be enlightening.

:)





.

[Soldier_Fortune]

I'm pretty sure ambient temperature, at ground level at least, has been modeled for a long time.

The fact they produced a v4.11 "read me" showing map temps doesn't mean they were not present long before v4.11

Desert maps ambient temps were @ 80-90' back on v4.07 iirc
You only had to look at the temp gauge on your aircraft with the engine off on the runway to see ambient temperature was in the map.
Which was always a bit strange as the engine was cold but the temp gauge registered outside temp.


I can't recall if the ambient temperature was present long before the patch 4.11: frankly I never paid atention to the outside temperature gauges until several weeks ago.
Now I've the game updated to 4.12.1 and I'll not downgrade it to a previous version to check that.
Might be those gauges originally were present for 'flavor' purposes only, without any other appreciable effect on the game's behavior (it wouldn't be the first time nor the last we saw something like).
But the fact is the IAS/TAS charts show the outside temperature was constant, it being 0 ºC for any map and any altitude, and we know they worked perfectly.

As I was telling you, I never paid atention to the outside temperature gauges until several weeks ago. And it was accidentally: while I was testing a bomb mission flying a B-25, I looked at the TAS gauge in the bombardier post after setting the bombsite with the aid of the IAS/TAS chart, and I saw that there were significant differences between the two readings. And I thought: "Shit! Is it a new bug?"
After some calculations with the E6-B, I could see the TAS gauge's reading was true. And looking to the outside temperature gauge for my very first time, I saw that the reading matched that of the real atmosphere for that altitude.

I have conducted numerous tests to confirm this, flying different planes in different maps.


Air density at altitude is the interesting factor though it seems something had changed.

:)

It is very important to understand that ground level temperature, altitude and density are closely related, and all together influences the TAS.

The standard formula for the air density at a given altitude below 11,000 m is:

AIR_DENS(Z) = AIR_DENS(0) * [(TGL + LAPSE_RATE * Z)/ TGL]^4.25

Where:
AIR_DENS(Z): air density at a given altitude Z
AIR_DENS(0): air density at 0 m ASL (1.22 kg/m3)
TGL: free air temperature on the surface (std temp = 288.15 ºK or 15.15 ºC). This temperature may be different than the standard temperature.
LAPSE_RATE: -0.0065 ºK/m, it is the constant rate at which temperature decreases with altitude.
Z: altitude ASL, measured in m.

So that formula explains why a plane, flying at a given altitude, may fly at a slower or faster TAS regarding of the Ground Level temperature.
The E6-B allows a pilot to calculate the TAS in one step, knowing the outside temperature, the indicated altitude and IAS: he doesn't need to know or to calculate the air density.:cool:

A word form TD would be enlightening.

+1. :wink:

[hafu1939]

As a FMB user trying to replicate real WWII events I need to calculate with TAS in flight plans. I use since 4.11 a freeware utility called AtmosCalculator. You can find it here: http://www.newbyte.co.il. This calculator is satisfactory for the use in Il-2, I hope it can help to solve your problems.

[Soldier_Fortune]

As a FMB user trying to replicate real WWII events I need to calculate with TAS in flight plans. I use since 4.11 a freeware utility called AtmosCalculator. You can find it here: http://www.newbyte.co.il. This calculator is satisfactory for the use in Il-2, I hope it can help to solve your problems.

Hi hafu1939!

Thank you for to share that tool with us.:wink:

But if you are a FMB user, surely you will need to considere the wind speed and its direction also (well... it's if you are including any wind in your designed missions).
In such case, the E-6B would be almost a 'must have': with that tool you will can calculate a lot of things relative to the flight.

In this link you will find general information about the E-6B: http://en.wikipedia.org/wiki/E6B

Following this link you can download de user manual of the E6-B in .pdf format: E6-B Instructions (http://www.mypilotstore.com/9035E458-8060-4CDF-90F2-9B6B2F44EF30/FinalDownload/DownloadId-3184372A77A7F90343025531AFD42164/9035E458-8060-4CDF-90F2-9B6B2F44EF30/mypilotstore/ProductDocs/E6B_Manual.pdf)

And in this link you'll have a realistic on-line simulation of the E6-B (it's a bit tricky to use: with left click and dragging you can move the disks; and with right click you can zoom it in and out): http://www.pilotinside.com/images/tools/e6b/e6b.htm#top

Give it a try, and let me know if you find it useful.

Have fun!:cool:

[KG26_Alpha]

I use Pilotwizz app on my Iphone

[Soldier_Fortune]

I use Pilotwizz app on my Iphone

Good!:D

That app has many of the features of an E6-B... and surelly with it you can compute faster than me.

However to recreate the enviroment of the '40s, for me my E6-B, a printed map, a pair of pencils, my plotter, and a song of Glenn Miller or the Andrews Sisters, are essential. LOL

The main difference between the app and the E6-B is you can use your iPhone inflight, wihile I must pause the game for to make my calculations, because I need my two hands to handle the E6-B.

Please, when you can, have a look at the links I've posted before. :wink:

[KG26_Alpha]

Im very familiar with the Wizz Wheel E6B

I just find it so obsolete (slow) for IL2 1946, with "Pilotwizz" I can use it on the fly very quickly :)

Also

The test maps from earlier in this thread >>> http://forum.1cpublishing.eu/showthread.php?t=40740 I used are showing @ -5' temp at @ 4000m

This still calculates from the tables as I have been using for years.

270kph ias
330kph tas
4000m alt
OAT -5'C

So somethings making them drop long if all the calculations are correct...........What inputs are the AI using for their bombing routines, as they don't seem to have a problem ?





.

[Soldier_Fortune]

Im very familiar with the Wizz Wheel E6B
...
Also

The test maps from earlier in this thread >>> http://forum.1cpublishing.eu/showthread.php?t=40740 I used are showing @ -5' temp at @ 4000m

This still calculates from the tables as I have been using for years.

270kph ias
330kph tas
4000m alt
OAT -5'C

So somethings making them drop long if all the calculations are correct...........What inputs are the AI using for their bombing routines, as they don't seem to have a problem ?

.

Hi KG26.

After reading your last post, I've conducted a test for each of both maps mentioned in that treath: Crimea and Moscow1 (winter).
I've done them with a B-25J because this aircraft is equipped with all the relevant guages for these tests: OAT, IAS/TAS, and Altimeter.

The payload were 2 x 1000 lbs bombs, being the targets:
- Crimea: a ring target placed in the air base of Simferopol (altitude = 800 ft =243 m ASL).
Moscow: the same type of target at the same altitude ASL, placed in the air base near to Vyazma.

The following data were obtained from the gauges readings (none was calculated, except the speeds in km/h):
CRIMEA:

- Wind speed = 0
- OAT at GL: 25 ºC
- Altitude during final approach to target: 13050 ft = 3970 m
- OAT at level bombing: 0ºC (should be -1 ºC)
- IAS = 160 mph = 258 km/h
- TAS = 200 mph = 323 km/h

MOSCOW WINTER:

- Wind speed = 0
- OAT at GL: -17 ºC
- Altitude during final approach to target: 13615 ft = 4150 m
- OAT at level bombing: -40ºC (should be -44 ºC)
- IAS = 160 mph = 258 km/h
- TAS = 186 mph = 300 km/h

Comparing this readings with the IAS/TAS charts, the data of the Crimea map are quite similar to them. The reason: the OAT at that altitude presents an irrelevant difference (-1 ºC).
But the outcomes obtained in the Moscow Winter map are too different when they are compared with the charts, due to the OAT differences as at GL as well as at flight altitude, like it is expected IRL.

I've engaged the Autopilot to have complete freedom for to read the gauges inflight, and because I was interested to see how the AI did do it.
May be an average AI bombardier is a bit idiot...the point is that it missed its targets in both maps, with the bombs falling too short and too far. :?

Anyway, I think the AI uses the gauges readings as inputs for the bombsite.

I have screenshots of the gauges in both missions. Tomorrow I'll try to upload them, and also I shall perform several flights in both maps to find out what data are the best to adjust the bombsite.

We will see the results... I hope.:wink:

[Soldier_Fortune]

Well... Finally I could perform a new test today to record an 8 minutes' .ntrk file: the last week end I should fix some issues with my hardware.

I've flown a bomb raid with a B-25 in the winter map of Moscow, and I can confirm all what I've said before:

1) The inputs for the bombsight must be the 'true altitude = indicated altitude - target altitude' (as ever), and the TAS corrected by OAT.

2) The OAT is indicated by the 'Free Air Temp' guages, or (if the plane has not such gauge) it must be calculated according to the Atmosphere International Standard (AIS) regarding of the altitude and the GL temperature.

3) The IAS/TAS charts and tables made and used before the release of the patch 4.11, are useless now.

You can see it in the attached .zip file.
Note that the speed used to set the bombsight is in knots, because yet was not fixed and old issue of the B-25: the TAS in the IAS/TAS gauge is indicated in mph, but the TAS must be converted into knots before it could be used as the speed input for its bombsight.

The values used in that test were:

Indicated ALT = 13150 ft
Target ALT = 800 ft
True ALT = 12350 ft
OAT = -40 ºC
IAS = 190 mph
TAS = 220 mph = 190 KTS
Payload: 2 x 1000 lbs bombs

The red values were used as inputs for the bombsight.

The bombs were released in automatic mode. The target was missed by very few yards, as we can expect: IRL it was practically impossible to perform precision strikes with high level bombing using the '40s optical devices, and a direct impact on an intended target was a matter of good luck. For pin point strikes, it's better to use dive bombers. For medium or heavy bombers it is better to use the carpet bombing tactics.

For me, this test (together with others which I've done) is conclusive.

Perhaps now we could talk about the other factors: wind speed, wind direction and how they affect the Ground Speed in navigation and level bombing. ;)

[KG26_Alpha]

Please repeat the test using a Russian Bombsite.


Bomb ground strike position relative to the bombsite aiming angle is the point to note also, testing shows this is wrong/different OAT air density or something is having an effect ?

If so new bombsite calculation tables are needed for v4.11 >


I have been a bit too busy to test again with new data this week but this is from a guide pre v4.11, hopefully the same theory applies to current game versions and the problem is else where.

http://img.photobucket.com/albums/v119/alpha1/angleCapture_zps908b95cf.jpg (http://smg.photobucket.com/user/alpha1/media/angleCapture_zps908b95cf.jpg.html)
Equations of motion
v = velocity, u = initial velocity, a =
acceleration, s = distance, t = time.
s = ut + ½at2
v = u = s/t (unaccelerated)
Fig 1.2.

The aircraft is heading from right to left at speed, v, when it releases a bomb at A.
Initially the bomb continues to move with the aircraft, but starts to drop as gravity accelerates it downwards.

The bomb follows a parabolic path, represented by the blue line.
AB is the height, h, of the aircraft and BC is the forward throw, R, of the bomb.
If the bomb takes time, t, to reach the ground, g is the
acceleration due to gravity and we ignore air resistance for the moment, then the equations of motion give us the following:

AB = h = ½gt² -- eq 1
BC = R = vt -- eq 2

We know the height, h, speed, v, and g is a constant 9.81 m/s², so we can find t from eq 1 and substitute for t in eq 2 to find the forward throw, R:

R = v 2h/g) -- eq 3

The angle between the horizontal – the dotted line in fig – and the point of impact at C is, of course,
the angle, a, from fig 1.1 above.
This is what we want to know when we come to aim the bomb and is the same angle as ACB in fig 2.
As we now know 2 sides of the triangle, AB and BC, we can find the angle:

Tan ACB = AB/BC = h/[v 2h/g)] -- eq 4


DIVE-BOMBING
In the previous example we used the height to find the time the bomb is in the air (equation 1) and
then used equation 2 to find the forward throw of the bomb.
From these two pieces of information we could deduce the angle corresponding to the amount the bomb drops from the horizontal.
We can do exactly the same when the bomb is released from a dive at an angle, degrees.
The situation is slightly more complex, however, because the bomb now has an initial downwards velocity (v.sin ) and the horizontal velocity (v.cos ) is not quite the same as the airspeed.

The equations for AB and BC now become:

AB = h = vt.sin + ½gt² -- eq 5
BC = R = vt.cos -- eq

Equation 5 results in a quadratic equation, which can be solved to find t.
Equation 6 can then give the forward throw, R, which allows us to find AB/BC and then the sight angle.

This would be quite tedious to solve for each combination of dive angle, airspeed and release height, but it is not too
difficult to produce a spreadsheet, which will do the sums for us once we enter the desired
parameters.
The dive angle, , is found by noting height, h, and range, D, to the point on the ground under the
cross hairs at the moment of bomb release.

Tan = h/D -- eq 7

Air resistance. We have not yet considered the effect of air resistance on the falling bomb.
Once the bomb leaves the aircraft it will start to slow down.
However, so long as the bomb does not produce any lift (either up or down), the drag will only act back along the bomb’s direction of travel.
The bomb will slow down and take longer to reach the end point, C in the above fig, but it will follow the same path and still reach that point.








.

[Soldier_Fortune]

Hi mate.:)

First of all: my sincere thanks by your explanation about the parabolic motion... but I know the works of sir I. Newton also. :grin:

BTW, I must point out an error in your eq. 3. It must be written as:

R = v . SQRT (2h/g)

Basically we are talking about of 2 types of bombsight: the Norden/Lofte type(Allies/Germans), and the OKPB-1 type (Russians). Both need 2 settings: TAS (horizontal speed), and altitude. The difference between both types is the first allows automatic or manual release, and the second only allows manual release. But in both types normally the aiming angle is internally calculated (all that equations you've posted run behind the scene).
The exception is the Norden/Lofte type when a player prefers the manual release; if so, he will must perform those calculations by himself (some players made an published their charts for manual release with the Norden/Lofte type, long before the patch 4.10).

According to my tests carried out several weeks ago, it seems that all bombs have the same FM, regardless of size and country (IRL the bombs' shape and weight are relevant, as well as the launching altitude, GS, OAT, and the wind's speed & direction).
As far as I can remember, when the atmosphere model had one only air temperature, the parabolic motion was almost perfect and it was very easy to adjust and to aim the bombsight, and to hit an intended target.
But now we have an atmosphere with different OATs at SL which change with the altitude, thus changing the air density dinamically.

I.e.: according to the AIS, if the OAT at SL is 25 ºC, we'll have:

Altitude (m)___OAT (ºC)___Air density (kg/m3)
0____________25_________1.225__(1.225)
1000_________18.5_______1.115__(1.088 )
2000_________12_________1.013__(0.966)
3000_________5.5________0.919__(0.858 )
4000_________-1_________0.831__(0.762)
5000_________-7.5_______0.75___(0.676)
6000_________-14________0.675__(0.601)
7000_________-20.5______0.606__(0.533)

* (The values into brackets are the air density at different altitudes considering a constant OAT = 0 ºC).

We could supose that any bomb released from a given altitude (say 6000 m), when t = 0, will have a constant horizontal velocity v = TAS (a/c), and an increasing vertical velocity u which range from 0 up to its final value. But both velocities will change with air densitý as the bomb is falling. Therefore, its path will not be perfectly parabolic as we could expect in a 'Newtonian Universe'.

Perhaps all bombs have the same in-game's FM... but they might work in a different fashion than that known before the patch 4.11.

Another factor which produce offsets between the aiming point and the hit point is how leveled flies the aircraft. If the pilot flies with the Level Stabilizer engaged, the aircraft may be flying at a steady altitude... but if its elevator is trimmed to avoid the 'sinking', probably its Angle of Attack (AoA) is not 0. The pilot will not be noticed about how is the AoA (the pitch), because the artificial horizon doesn't work when the LS is on, and because we haven't an 'AoA gauge' like the modern aircrafts have.
Thus, with that configuration, when the bombsite is at 0 º elevation, really it will be aiming at 'AoA' elevation.

I.e.: if the AoA is +3º, this angle adds to the bombsight elevation. A bombardier aiming to a target with a BS elevation = 50º, really is like if he would be setting an elevation of 53º, and then he adjusts the TAS and/or altitude to fix the target under his crosshair according to that wrong angle... which will worsen the final outcome.
A difference of 3º may seem a small thing; but if we make same calculations according to the equations you've posted:

Wrong elevation = 53º (the bombardier believes the elevation is 50º)
tan (53º) = 1.327
Right elevation = 50º (if the aircraft would be flying perfectly leveled)
tan (50º) = 1.192

According to your eq 7,

D(53) = 5000 x 1.327 = 6635 m
D(50) = 5000 x 1.192 = 5960 m

As you know, the most of players engage the Auto Release when the elevation is about 50º. Even if the crosshair is fixed over the target (what would be rare in this case), the bombs will fall about 675 m short because of the early release.

...

Other unavoidable errors related with the type Lofte/Norden BS:

This bombsite has not a 'coarse/fine' setting, but one only mode with 2 fixed rates: one for the TAS and the other for the altitude. The rate for altitude is 50 per keystroke, and that for TAS = 10 per keystroke.

But, depending on the chosen bomber, we have the following combinations:

- German bombers: TAS rate = 10 km/h; altitude rate = 50 m.
- Allied bombers: TAS rate = 10 KTS; altitude rate = 50 ft.
- Japanese bombers: TAS rate = 10 KTS; altitude rate = 50 m.

Thus, 1 keystroke of TAS in an Allied bomber BS is almost equivalent to 2 keystrokes in a German bomber; and conversely, 1 keystroke of altitude in an German bomber BS is almost equivalent to almost 3 keystrokes in an Allied bomber.
In short: German bombers allow more accurate TAS settings than the Allied, but the latter allow more accurate altitude settings than the German.

Other errors come from the instrument readings: sometimes the pilot visually must interpolate between two marks, and can be difficult to decide if he's reading a value of 12,600, or 12,700, or 12,800...

I'm wanting to emphasize that, even if the calculations were very accurate, the game interface makes it impossible to apply them exactly.

...

This evening I'll try to perform more tests, as you've suggested: one with a Russian bomber, and other with a German bomber at least.

See you later! :cool:

[KG26_Alpha]

In short................ :)

Something don't add up with current Bombsite data/settings/interface.

Some TD input would be favorable as to what they did or didn't do.

Good luck with the Russian Bombsite testing.

[majorfailure]

I don't know much about Bombsights, but wouldn't they at least include some kind of water level to allow for the bombardier to set it facing downwards -no matter what AoA the plane has?

[Soldier_Fortune]

Well... I've performed two tests: one with a Pe-8 and other with a He-111, flying in the Moscow 1 (winter) map.
Both tests confirm all what I was telling until now: the TAS, when used as settings for the BS, are different than those indicated by the actual charts, and they regards on the OAT and the altitude.
The attached file contains tracks of both tests.


Something don't add up with current Bombsite data/settings/interface.
...

I wouldn't say so...
It doesn't add up if you compare the tests' outcomes with the actual charts. But these tests show the internal consistency of the in-game's atmosphere model.

BTW, I've found the actual charts are not completely useless after all.:grin:
Yesterday, checking speeds at different altitudes higher and lower than the range from 4000 to 5000 m, calculating them with the wizz wheel and comparing my results with the charts, I realized that those charts were made for an OAT = 25 ºC @ MSL.
Thus, they may be used only with the following maps:

Iasi (on line)
Crimea
Kiev
Balaton
Hawaii
Midway
Kuyshu
Net 8 Islands

The bad news is that there are other 56 maps in the game, covering a range from -20 upt to +30 ºC.
If the new charts were made for starting OATs from -20 up to +30 in steps of 5ºC each, it would mean 11 charts to cover all the maps (plus other maps included in some mods).
But then it would be necessary to considere all the Altitud/IAS/TAS combinations:

- Altitude in m and IAS/TAS in km/h (Germans, Russians, Italians)
- Altitude in ft and IAS/TAS in mph and kts (Allies)
- Altitude in m and IAS/TAS in kts (Japanese)

This gives us... 33 different charts!!:shock:

Do you really think the players would feel comfortable managing so many papers?
IMHO, perhaps it would be better and easier to learn how to use the E6-B, or an app like pilotwizz.:roll:

Back to my last tests: the bombs fell faily close to the target.
At this point I'm considering that perhaps the altitude (used as input for the BS) should be corrected by OAT, instead of using directly the indicated altitude, to get a better accuracy.
Which leads us back to the question with wich I started this treath: What should we use: the indicated altitude, or the corrected ('true') altitude?

It's very easy to check the TAS: we have some aircrafts with IAS/TAS guages. But we haven't other than the barometric altimeter... so, if TD doesn't fire a starshell for us, more testing will be needed. :?

.....................

Edit: The page doesn't let me to upload the zip file containing the tracks. Perhaps tomorrow...:rolleyes:

[Soldier_Fortune]

I don't know much about Bombsights, but wouldn't they at least include some kind of water level to allow for the bombardier to set it facing downwards -no matter what AoA the plane has?

Hi!:)

The OKPB-1 Bombsight (Russian) has a bubble in its centre, wich indicates whether the aircraft is flying flat and leveled or not. The other bombisghts don't have a similar device.

The real Norden BS had an autopilot wich, when it was engaged, kept the bomber on the right path.
In-game, that autopilot is not modeled. Instead, the Level Stabilizer helps the player with respect to that.

But the LS shouldn't be considered a 'solution' to level a bomber from any situation, but just a help.

This means the player must be sure that the bomber is flying flat and leveled at the right speed, altitude and heading, before engaging the LS to lock the airctraft on the desired configuration. To achieve this, the player must know the behavior of his bomber at any altitude and must to know how to trim it properly. :cool:

[KG26_Alpha]

I've already stated the charts are not totally inaccurate,
but using Bombsite data even with a wizz wheel or Pilotwizz the bombs still drop longer/shorter than they should,
even when you taken have in to account ground elevation of the target,
I still have to use a "feeling" of where the bombs "might" hit instead of accurate an bombing solution
with the correct input data.

Tested ac:
Pe2
IL4
The payloads on these aircraft all drop long as pointed out in an earlier thread >> http://forum.1cpublishing.eu/showthread.php?t=40740

He111
Payload drops short of aiming point, where as they used to run in from the start point of the bombsite.
The SC50 track is interesting as it hits before the aiming point and then long as you would expect from 32xsc50's


But as I have already said also, these bombsite shouldn't be too accurate, but some explanation the payload drops inconsistency would help matters,
be it the air density changes or other factor.






.

[Soldier_Fortune]

Hi...!

Finally I could upload my last tests: one with a Pe-8 and other with a HE-111.

Today I may not see your tests because I haven't IL2 installed in this computer (perhaps tonight or tomorrow).
BTW: what maps have you used? It is importan to know it.

[KG26_Alpha]

BTW: what maps have you used? It is important to know it

Crimea

[Soldier_Fortune]

The OAT at MSL is 25 ºC for Crimea. Thus, the old chart remains useful in that map.
But, when it is used with winter maps, it just gets mislead the reader.

I've made a chart for OAT = -20 ºC, and I'm attaching it to this post.

Please: When you can, play a bomb mission using the Gulf of Finland Winter map, and observe how much 'feeling' you need to apply whether using the old chart and the latter.

[KG26_Alpha]

Have you checked the bombsites accuracy with different payloads ?

Even on the Crimea map its wrong especially the Russian bombsite.

Its very inconsistent compared to how it was before, with the bomb blast radius reduction and other bomb related adjustments, its become very laborious and painful to make a bomb run not knowing where the bombs are going to hit and see such little damage made by them if you just a few feet away from a target.

:confused:

[Soldier_Fortune]

Have you checked the bombsites accuracy with different payloads ?

Even on the Crimea map its wrong especially the Russian bombsite.

Its very inconsistent compared to how it was before, with the bomb blast radius reduction and other bomb related adjustments, its become very laborious and painful to make a bomb run not knowing where the bombs are going to hit and see such little damage made by them if you just a few feet away from a target.

:confused:

I'm doing my tests with different payloads and, as far as I can see, there is not relevant differences among them: russian bombs tend to fall long while the german ones tend to fall short.

Even on the Crimea map its wrong especially the Russian bombsite.

Last evening I was testing "how much feeling is needed" for an accurate targeting using the russian bombsight, with both Gulf of Finland maps.
And I was realized that the TRUE ALTITUDE (it means: Indicated Altitude corrected by OAT) has something to do as I suspected.
I've got very good shots in both maps in this way... but more tests are needed using different payloads and different russian bombers.
Other similar tests should be made for manual targeting with the Norden/Lofte bombsight.

Rgardless of the blast radius (it only could be fixed or modified by TD) I'm pretty sure that we're going in the right direction.
The level bombing is more laborious than before... but now is a bit closer to the real life. Perhaps we'll find a method to systematize the process and to make it more accesible to any player. :wink:

[KG26_Alpha]

The OAT at MSL is 25 ºC for Crimea. Thus, the old chart remains useful in that map.
But, when it is used with winter maps, it just gets mislead the reader.

I've made a chart for OAT = -20 ºC, and I'm attaching it to this post.

Please: When you can, play a bomb mission using the Gulf of Finland Winter map, and observe how much 'feeling' you need to apply whether using the old chart and the latter.

Will test this soon.







.

[Soldier_Fortune]

Hello!:)

Yesterday I was carrying out more bombing tests, and I realized that actually with the Lofte BS the manual targeting is much more accurate than the auto targeting. Well... really we could say: actually the manual targeting is the only accurate method for level bombing. :rolleyes:
This has a problem: the player should do all the calculations related with 'parabolic motion' and the BS elevation angle by himself.

I also tested the manual targeting with the OKPB-1 bombsight. And, surprisingly, I realized that the in-game calculation indicates an elevation angle greater than the calculated manually. The difference is about 3º, regarding of the altitude and the OAT, and that is sufficient to produce the observed longer drops with the russian bombers.

Thus: The intended aiming method of both types of bombsights (Lofte/Norden and OKPB-1) don't work as it should do.

Other important matters about manual targeting with both bombsights:

- The TAS must be calculated taking in account both the Indicated Altitude and the OAT at such altitude (remember: the OAT depends of the chosen map).

-The altitude to use for the BS' elevation angle calculation must be the True Altitude: it is found from the Indicated Altitude affected by OAT and then subtracting the Target Altitude.

All indicates that now the atmosphere model is more accurate and more consistent with the laws of Physics, and the aircrafts as well as bombs exhibit a more complex but predictable behavior according with a given combination of external conditions: altitude, OAT, wind, etc. Almost like IRL...:cool:

But perhaps something was missed about the bombsights along the succesive improvements, since the patch 4.10 until today.

I'll do more tests with different maps and with American and Japanese bombers. In the best case, such tests should confirm what was observed with the He-111 and the Pe-8.

[Soldier_Fortune]

Hi...! :grin:

Lately I was performing more tests.

First of all, I was mistaken about the altitude setting for manual targeting of the BS: it must be the Indicated Altitude.
I had seen the error when I tried to repeat my tests wih winter maps (for maps with OAT between 20 and 25 ºC @ MSL, at an altitude of 5000 m the difference between True Altitude and Indicated Altitude is practically negrligible).

I've made other tests, this time including the effect of the wind to see how it affects the calculations for manual targeting.

The observed effects (always with manual targeting) were:

1) Always, and regarddless of the wind direction and speed, it's needed to calculate the Ground Speed (GS) and the Wind Angle Compensation (WAC).
This is best done with an E6-B Flight Computer.

2) In order to mantain the True Course to the target, the aircraft must be pointed to a True Heading = True Course + WAC (or -WAC, regarding if the WAC is to the right either to the left).

3) For nose wind GS is less than TAS. Conversely, for tail wind GS is greater than TAS.

4) GS, and not TAS, is the speed input for the BS. TAS may be used only when Wind Speed = 0 (this is the only case in which GS = TAS, as it was until the patch 4.09, when the wind wasn't included in the FMB).

5) Indicated Altitude is the other input for the BS.

6) The BS must be aimed using its Side Slip command, with an angle = WAC, but with the opposite sign; i.e., if WAC = -7º then side slip angle = +7º.

7) The bomber must mantain both the True Course and True Heading, at least until the bombs are released.

If all the above is satisfied, the cross wind will make the bombs hit on the target.:cool:

[Soldier_Fortune]

Good morning. :)

I've made and attached below a set of 4 printable Manual Targeting Charts. The Readme into the .zip file explains how to use them.

The cons of these charts: they must be used together with an E6-B Flight Computer.
The pros: they are printable and can be used in-flight.

It is very easy to learn how to use an E6-B, and really it is a cool and useful tool... specially if you like to fly without waipoints.
IMHO, Il2 linked to a combo of printed maps and charts, an E6-B, a plotter and a pencil, is the more realistic and historical approximation to the work that made the airmen in the 40's... for pre-flight planning and navigation, at least.:cool:
The price of an E6-B ranges from about 15 up to 50 U$D, regarding of its material (metal, plastic fiber or paperboard) and its trademark, and it can be purchased in aviation stores and online.

But perhaps many players would prefere a "digital age" solution instead of the proposed "old analog age" method.
Yesterday I found this thread in the Warbirds of Prey forum (http://www.warbirdsofprey.org/index.php?topic=11147.0), containing a very complete calculator for manual targeting. It does all what we were talking about in this treath in a very fast way.
I used it to compare the BS Elevation Angles obtained with my charts against those obtained with this calculator: within the desirable accuracy limits, the differences are negligible.

The pros of this calculator: very easy to use and the user doesn't need to learn nothing.
The cons: it is an online calculator and therefore it can not be used inflight; the player must pause and minimize the game and then open the calculator.

Well... Now the level bombing fans have two different methods to perform manual targetings. Both are very accurate and replace the old and obsolete charts and tables. So the choice depends on the tastes of each player. :cool:

[majorfailure]

The cons: it is an online calculator and therefore it can not be used inflight; the player must pause and minimize the game and then open the calculator.

Look further down in the thread you posted a link to, and there you will find a downloadable version.
I'm gonna test this when I've got time, and if it works then there is potential fun in it, now that i've got the basics of level bombing (and the both of you Soldier_Fortune and KG26_Alpha gave me some hints here why I'm not hitting as good as i wished for -so thanks to the both of you)

[Jeremiah_Weed]

Howdy. I noticed and started reading this thread about a month ago. Then got extremely busy at work on some end of fiscal year projects that need to get out and just haven't had time to post anything. I don't want to butt in on your research so I won't say too much...you may be like me and love the challenge of figuring stuff out.
But I will say this....true altitude and indicated altitude are basically the same thing. The difference being true altitude would be what a tape measure placed between sea level and your plane would say and indicated altitude would be what your instruments tell you. With modern laser and radar equipment, the difference between the two could be mere inches. In addition to indicated altitude, there are 2 other altitudes you need to bomb accurately. Here's a list of the different altitudes....

http://www.meretrix.com/~harry/flying/notes/altitudes.html

Also, you don't need adaptive bombing. There are definite formulas that are used, but some planes use slightly different values. Also, the IAS/TAS chart that's in the game is only giving you the partial equation...so the values for TAS are usually WAY off. That chart shows the aircraft's speed increasing linearly (on a straight line), but it actually increases on a curve. Fortunately, you don't need a differential equation to calculate it...a simple polynomial is all that's needed. In other words, basic mathematics. LOL
And yes, OAT (Outside Air Temperature) is very important for calculating that curve. With OAT in mind, I recently noticed that the Free Air Temperature gauges on the G4M1-11 Betty are bugged. I've reported it to DT so hopefully it will get fixed. Having air temperature gauges that work properly come in quite handy. :grin:
Anyway, I've said enough...but if you guys would like some help, just let me know.

[Soldier_Fortune]

Hi Jeremiah. Thanks for your interest.:)

As I already stated, in this sim there is not difference between Indicated Altitude (the altimeter reading) and True Altitude (altitude affected by local pressure and OAT at a given altitude). But True Altitude is modeled in other sims (i.e., LOMAC Flamming Cliffs 2).

Will True Altitude be modeled in IL2 in a next future? Really I don't know. But if TD decides to model it, True Altitude will affect the level bombing. In any case, it can be easily calculated with an E6-B, as actually TAS and Ground Speed must be calculated for an accurate level bombing.

Also, you don't need adaptive bombing. There are definite formulas that are used, but some planes use slightly different values. Also, the IAS/TAS chart that's in the game is only giving you the partial equation...so the values for TAS are usually WAY off. That chart shows the aircraft's speed increasing linearly (on a straight line), but it actually increases on a curve. Fortunately, you don't need a differential equation to calculate it...a simple polynomial is all that's needed. In other words, basic mathematics. LOL
And yes, OAT (Outside Air Temperature) is very important for calculating that curve.

I was trying to express all those formulas with a set of printable graphic charts for manual release of bombs in level bombing.
I personally am quite skillfull handling the E6-B and I have no difficulty solving all those equations with it while flying. But, at the same time, I know that may be many players would prefer to have something easier to handle, and I've made that set of graphic charts with that goal in mind (you can download it from the post #30 in this thread: I would like you test them, and then let us know your opinion).
But also, in that post, I adress to a link to the 'Warbirds of prey' site where you will find a nice calculator to obtain all relevant data for an accurate manual level bombing, in a more friendly way (for many people, at least) without an E6-B : Ground Speed and bombsight elevation, taking in account OAT and wind.

With OAT in mind, I recently noticed that the Free Air Temperature gauges on the G4M1-11 Betty are bugged. I've reported it to DT so hopefully it will get fixed. Having air temperature gauges that work properly come in quite handy

Yes: I also noticed that during my tests. And I was about to report that issue when I saw it was already reported.:grin:
But, until it is fixed, you always can calculate the OAT easily; for 'Betty' it is:

OAT (ºC) = Tmap (ºC) - 0.0065 (ºC/m) * IALT (m)

Anyway, I've said enough...but if you guys would like some help, just let me know.

Well... in these matters is never 'enough', and any help, advise or proposal is always welcome.;)

[Jeremiah_Weed]

Howdy SOF.
If you enjoy catching someone parked on an airfield 5000 meters below you or just like being able to drop an egg on your target and hit it, then you'll enjoy this. It looks like you already know these maps are somewhat based on ISA (International Standard Atmosphere) and also that temp rises by .0065 deg C per meter. Also, that 15 deg C is the temp at sea level for ISA normal, at least for one, so I don't really need to go into any detail about that. (I believe there is another ISA that starts at 0 deg C, but we'll ignore that one)

So, on to one of the formulas. While looking at the IAS/TAS chart, I was able to derive a formula that came up with their numbers:

(IAS * .0657 * (ALT/1000)) + IAS = TAS

I quickly realized that this formula didn't take into account changes in OAT (Outside Air Temperature) and it wouldn't have been on a curve...so I modified it. What I came up with is this:

((IAS * .066 * (ALT/1000)) + IAS) * (1 + ALT/100,000) = TAS

Using real numbers, let's say you had an IAS of 260kph and an (indicated) altitude of 4850m. The equation would look like this:

((260 * .066 * 4.850) + 260) * (1.04850) = TAS

In operation, you would multiply the 260 by .066 then multiply that by 4.850, then add the 260 to arrive at a temporary airspeed. You would then multiply the temporary airspeed by the 1.04850 to arrive at your TAS.

Now, here's the deal. The .066 factor is only for some planes, like the B5N1 Kate (my favorite bomber). Russian planes like the Pe-8, the IL-4 and some others use .084. The He-111 H-2 uses .026 and the H-6 uses .046. Also, this formula is used on other maps where the temperature is different (above or below ISA), but it's calculated differently. Namely, you'll be calculating for density altitude. But I'll get into that later on.

I tested this formula by using the Gulf of Finland 1 (summer) map, since it was ISA normal. I used the Island of Lavansaari/Moschnyi as a base and put several air starts in grid AV-11 to the east of it, ranging from 1000m all the way up to 6000m. I also put a sizable group of cargo ships in grid AR-11 to the west and also placed a "destroy ground" icon in the middle so I could see it on the map well before I could see the ships.

The distance gives you time to trim your plane (especially the rudder) and get it stable at altitude without any control inputs before kicking in "auto level". I also cut back on power and prop pitch...some planes not as much as others. Also, I found that as altitude increased, accuracy started to suffer, although not as much as you would expect. I'm still able to zero a freighter at 6000 meters alt with that big ole 5000 kilo monster the Pe-8 drops. :grin:

Anyway, if you want, get set up on that map and get used to running the numbers on your way to the target. Then, when you're ready for temperature changes, let me know. Additionally, I think a calculator will do you much better than your E6B due to the variations in the velocity factor. (.084, .066, .046, .026, etc) :grin:

[Jeremiah_Weed]

Also, I forgot to mention, if you're testing out the Lofte/Norden type bombsights there's a trick to them. Don't try to track your target forever. They aren't designed for that. Only track your target about 3 or 4 degrees at the most. For instance, if you find the bombs release around 35 degrees at a given altitude, manually move the bombsight angle no farther than 38 or 39 degrees. As your sight moves over the target, enter it into auto mode and let it do its job. If you don't try to track your target forever, they're just as accurate as the OKPB-1 sights.

You can also "tweak" it a bit before you enter into auto mode. If the actual TAS is 2 or 3 kph HIGHER than what you entered as the bombsight velocity, you can move the bombsight altitude DOWN 10 or 20 meters in elevation for fine adjustment. The reverse is also true.

Note: The Betty uses this type of bombsight and its velocity factor is .046.

Bombs away! :grin:

[Jeremiah_Weed]

As time permits, I'll post a more sophisticated formula. The one I posted starts to become inaccurate above 6000 meters. The last factor needs to have a Delta/Rate of Change factor in it to slow down the rate of increase, which usually requires the use of exponential function. I've purposely avoided that because I'm not sure most players would enjoy having to (or be able to) work the equation.
This one is relatively simple and still allows you to hit your target the majority of the time and have some fun...and fun is what it's all about. ;)

[Soldier_Fortune]

Hi again Jeremiah :)

I would like to coment some points of your posts:

It looks like you already know these maps are somewhat based on ISA (International Standard Atmosphere) and also that temp rises by .0065 deg C per meter. Also, that 15 deg C is the temp at sea level for ISA normal, at least for one, so I don't really need to go into any detail about that. (I believe there is another ISA that starts at 0 deg C, but we'll ignore that one)

As far as I tested, ALL maps in IL2-1946 are based on ISA.
In all of them the OAT decreases from the given free air temperature @MSL at a lapse rate of -6.5 ºC/km_altitude. It can be checked reading the OAT gauges in diferent planes, while flying whatever map.
Under ISA, the lowest temperature of the troposphere is -56.5 ºC; and, for the standard condition (15ºC @MSL), that temperature is constant from 11,000 m up to 25,000 m. But, what if the OAT @MSL is not the standard?
Well... if the OAT @MSL is greater than 15ºC you will find the lowest temperature at a higher altitude than 11,000 m; and if the OAT is smaller than 15ºC you will find the lowest tropospheric temperature at a lower altitude than 11,000 m.
Since the OAT at a given altitude affects the air density, it also will affect the TAS.

So, on to one of the formulas. While looking at the IAS/TAS chart, I was able to derive a formula that came up with their numbers:

(IAS * .0657 * (ALT/1000)) + IAS = TAS

I quickly realized that this formula didn't take into account changes in OAT (Outside Air Temperature) and it wouldn't have been on a curve...so I modified it. What I came up with is this:

((IAS * .066 * (ALT/1000)) + IAS) * (1 + ALT/100,000) = TAS

- First of all: what IAS/TAS chart were you looking at, exactly?
Is it the kown IAS/TAS chart used since 6 years ago?

- 2nd: Both of your equations give a TAS higher than that obtained with the ISA's equations, or than that measured in-game.
I.e.: altitude = 5000 m; IAS = 250 km/h; OAT = -7.5 ºC (25 ºC @MSL)

With your 2nd equation, TAS = 349 km/h
With an E6-B, TAS = 320 km/h
With the published IAS/TAS chart, TAS = 332 km/h
With ISA equations: 319,5 km/h

It's easy to check what TAS is right: at least there are 2 aircrafts equiped with TAS gauges: Me-262 and B-25J. Any pilot can ride them to fly at that altitude over Crimea, and read both IAS and TAS.

3rd: Regardless the mathematical method used to relate variables, constants of proporcionality found or made during the process must be consistent with what those variables are representing. That formal consistency must cover the measurement units also.

((IAS * .066 * (ALT/1000)) + IAS) * (1 + ALT/100,000) = TAS

I gather 0.66 is measured in 1/km in the above equation, and 1000 is measured in m/km. In this way the first parenthesis gives outcomes in km/h, and it is consistent. Right?
But... what does 100,000 within the second parenthesis mean?
If ALT is measured in meters, 100,000 must be measured in meters also, because 1 in this case has not dimension.
But then, why "100,000" and not any other arbitrary value? If "100,000" would mean "100,000 m", it is far beyond where our planes can fly... and I see no reason to consider a value of altitude unattainable for any aircraft, including the most modern ones.

4th: You've found diferent constans of proporcionality for diferent planes: 0.066 for B5N1; 0.084 for Russian bombers; 0.046 for G4M11; 0.026 for He-111 H2 and 0.046 He-111 H6... In few words: a diferent constant for each bomber, for one only map, and for altitudes below of 6000 m.
Perhaps I'm unable to get your point but... why one should use so complicated methods instead of the more realistic and simple ISA equations, already implemented in any 'wizz wheel' or in the 'Warbirds of prey' calculator?
And: will those constants be valid when you enter the wind?

Also, I forgot to mention, if you're testing out the Lofte/Norden type bombsights there's a trick to them. Don't try to track your target forever. They aren't designed for that. Only track your target about 3 or 4 degrees at the most. For instance, if you find the bombs release around 35 degrees at a given altitude, manually move the bombsight angle no farther than 38 or 39 degrees. As your sight moves over the target, enter it into auto mode and let it do its job. If you don't try to track your target forever, they're just as accurate as the OKPB-1 sights.

You can also "tweak" it a bit before you enter into auto mode. If the actual TAS is 2 or 3 kph HIGHER than what you entered as the bombsight velocity, you can move the bombsight altitude DOWN 10 or 20 meters in elevation for fine adjustment. The reverse is also true.

This is a very good advise for a 'auto track and targeting' with the Norden/Lofte bombsights, and perhaps it could be combined with the 'ISA method'. I'll test it when I come home (sadly I've not IL2 installed in this computer :mad:) :grin:

OK... You've been working very hard and I hope my comments are not offensive for you. But, under my own experience, I see you might be getting into a method of analysis which may give you more problems than solutions, despite its apparent simplicity. :rolleyes:

See you soon.;)

[Jeremiah_Weed]

Howdy SOF
Let's see if I can clear up some confusion here.
Regarding your question about the 100,000 figure. It is NOT a measure of any distance or altitude. It's simply a mathematical value that let's you know you are converting the altitude to a decimal to be used in the equation.

Also, with regards to me perhaps over-complicating things, I'm actually attempting to do just the opposite. Take a second and look up the wiki article on the E-6B (whiz wheel) calculator. See the equations? For me, those are quite manageable...they're basic trigonometry. Something I have to use every day. But I don't think most players would enjoy number crunching them on their way to a target. :grin:

While still on the subject of the E-6B, I'm assuming you have been unable to obtain good accuracy using it and that's what prompted this thread. Am I correct? In fact, I'm thinking the different values like .084, .066, .046, etc., are being used to PREVENT the use of an E-6B calculator. Also, I don't think the numbers my equations are coming up with are the actual TAS of the aircraft, it's just the numbers the game is using to drop bombs. I'm thinking they have taken "special liberties" with Newtonian physics (classical mechanics) in the game and that bombs don't precisely follow established flight paths based on actual physics.

Also, why are you using a Crimea map? Remember, in the scientific method you need to establish a control group and establish some baseline figures. To do that, you need an ISA neutral map (15 deg C) that allows bombing at sea level. There were only a couple of maps that allowed that; Gulf of Finland 1 and a generic Island map. The Crimea map is 25 deg C which is 10 deg C above ISA and you would need to factor in the difference in density altitude...which can be done with my equation. (But I haven't revealed how yet.)

I am curious however. I'd love it if you set up for bombing on an ISA neutral map (15 deg C) with your targets at sea level just to see if you get any accuracy using your E-6B with various types of aircraft.

Also, your comments are not offensive. Not even slightly. So don't worry about that. As for my method, I have a background in engineering, applied science and production engineering, and geology. I work for a company that provides technical and material assistance to the mining industry. I spend a large portion of any given month conducting failure analysis, so trust me, my methods are geared towards finding out why things aren't working properly and finding simple solutions rather than over-complicating things. There's a method used in engineering called the KISS method....it means Keep It Simple, Stupid. LOL And I live by it. :grin:

Anyway, back to work. Things will be quite hectic from now until end of the year, but I'll try to re-work that equation to add a Δ (Delta) factor in which will slow down its rate of increase...and avoid trig or calculus. :grin: Also I'm thinking the factors like .084, .066, .046, etc., may be the factor that needs to change with density altitude. But we'll see.

Oh, I almost forgot, the IAS/TAS chart I'm looking at is the one supplied with the game. It should be in the main folder as a .pdf file. You can also view a copy of it online. While running the numbers, I also noticed that things started to change once you reached 10,000 meters altitude, so I quickly realized they were taking into account changes that occur once you start entering the stratosphere.

Anyway, if you can, please let me know what you find out using an E-6B on an ISA neutral map. I am curious about that.

[KG26_Alpha]

Also, I don't think the numbers my equations are coming up with are the actual TAS of the aircraft,
it's just the numbers the game is using to drop bombs.
I'm thinking they have taken "special liberties" with Newtonian physics (classical mechanics) in the game
and that bombs don't precisely follow established flight paths based on actual physics.



I had already come to that conclusion using Pilotwiz Iphone app I find it faster to use than E-6B in flight.

I was waiting for an official reply from TD but I'm not sure there will be one or if they understand whats going on in the game.










.

[Jeremiah_Weed]

Howdy Alpha.
Thanks for joining back in. I was wondering if anyone had come to that conclusion. Also, it looks like you are unable to get satisfactory accuracy across the board with all types of planes using the E-6B, or in your case, the Pilotwiz.

During a break at work today I was pondering this issue. I came up with an idea to test if the game is actually using classical mechanics when it comes to dropping bombs. It won't tell you that it is using classical mechanics, but it will tell you right off if it isn't. (The only way to know that it IS using classical mechanics is to measure precisely the distance from drop point to target and the time from drop to impact.)

Here's the test:
Set up a map with 3 or 4 bombers of different types spawning at the same altitude and speed, all following a parallel course in the same direction. The target for each would be a ship, which would also be placed even with each other (abreast, juxtaposed) along the planes flight path. I'm thinking the skill level for the pilot/bombardier should also be set to ace.
The planes would need to use different factors. I know the B5N1 and the Pe-2 use .066. All the other Russian bombers use .084. I think the Betty uses .046. And I think I listed some of the others above. Anyway, so you'd have one of each. So maybe a Betty, a Pe-8, an He-111, and maybe a Ju-88.

Now, in classical mechanics certain things would be inevitable. You would not need to move the ships out of being in a line abreast in order for the bombs to drop at the same time...since they would all follow the same flight path, AND, they would all hit at the same time since gravitational acceleration (constant) would be the same.

There are only a few things that could cause a different flight path: increased drag, something like a rocket motor applying thrust, and/or control surfaces. So unless you're dropping a para-bomb or one of the FritzX types, this should be a good test.

If you have to move the ships or they (the bombs) don't hit at the same time, then the gig is up.

I won't be able to try this until this weekend, but hey, if you have a chance and the time, give it a whirl and post the results. Maybe this is an unreported bug, but my gut tells me they did it on purpose.

Again, thanks for posting in with your info. :grin:

[Soldier_Fortune]

Hi all!:)

Jeremiah: I am an experienced engineer also, but that is not relevant here. However, since we have the same profession, we certainly must share the basic concepts about Mathematical Calculation.

Regarding your question about the 100,000 figure. It is NOT a measure of any distance or altitude. It's simply a mathematical value that let's you know you are converting the altitude to a decimal to be used in the equation.

1) The calculation rules are rigid and do not allow exceptions.

2) It is not allowed to transform arbitrarily an absolute amount into another relative: for such a transformation to be valid, the absolute amount must be refered to another which can be considered as a basis or reference in a consistent manner.

Thus, you are not free to transform "4850 meters" into "0.0485 p.u." (or "4.85%"), because always you will must answer the immediate question: "0.0485 p.u. (or 4.85%) of WHAT?"

Also, why are you using a Crimea map? Remember, in the scientific method you need to establish a control group and establish some baseline figures. To do that, you need an ISA neutral map (15 deg C) that allows bombing at sea level. There were only a couple of maps that allowed that; Gulf of Finland 1 and a generic Island map. The Crimea map is 25 deg C which is 10 deg C above ISA and you would need to factor in the difference in density altitude...which can be done with my equation. (But I haven't revealed how yet.)

And, why are you using a chart which returns TAS for (roughly) 25 ºC @MSL, with a map of 15 ºC @MSL? :confused:

If you are looking for a good method to find the in-game IAS/TAS relationships with any map, I could suggest you to fly a B-25J: it has IAS/TAS and OAT gauges, and altimeter. These three instruments are all you would need to see differences and matches of TAS for different altitudes and thermal conditions. This aircraft perfectly could serve as the control case for your research.

Also, with regards to me perhaps over-complicating things, I'm actually attempting to do just the opposite. Take a second and look up the wiki article on the E-6B (whiz wheel) calculator. See the equations? For me, those are quite manageable...they're basic trigonometry. Something I have to use every day. But I don't think most players would enjoy number crunching them on their way to a target.

Waht the wiki's article shows about E-6B are the equations to solve the 'triangle of speeds' in order to find Ground Speed and True Heading when there is any wind. Those equations may be solved mathematically (applying the Theorem of the Sins), or geometrically (drawing the vectors of a/c's and wind's speeds in a given scale, and then measuring the modulus of the resulting vector with a ruler, and the angles with a protractor).
The back side of the E6-B returns GS and TH in few seconds, solving the triangle of speeds in only two steps, and avoiding to use complicated equations.

The front side of the wizz wheel is designed to obtain TAS from IAS (among many other calculations), regarding of the OAT and altitude, in one step and no need to solve all and each of the ISA equations.

Perhaps it's needed to define what the E6-B really is: It is an Analog 'Flight Computer'.
An Analog Computer (it is not the matter if it is an electronic or mechanical analog computer) is programmed by hardware. Therefore, it can only do that for which it was designed and built, and it must be considered a "specialized" tool.
The E6-B basically is a circular slide ruller, but specially designed to perform flight calculations in the easiest and fastest manner as possible.

Of course, today we can find apps like 'Pilotwizz' (this is only for iPhone), or 'FlightTools E6-B' (it is for Android and iPhone). But the usage of a smartphone or a programmable calculator while I'm flying an IL-4 over Eastern Prussia in 1944, is not realistic (and therefore funny) for my taste.:)

Also, I don't think the numbers my equations are coming up with are the actual TAS of the aircraft, it's just the numbers the game is using to drop bombs. I'm thinking they have taken "special liberties" with Newtonian physics (classical mechanics) in the game and that bombs don't precisely follow established flight paths based on actual physics.

Mate: I've been testing all sort of bombers, maps (my lattest tests were performed just with both Finland maps), and winds. The result is expressed in the charts I've attached to the post #30.
I've achieved accurate hits using manual targeting & drops.

I don't think that TD have taken such "special liberties" with Physics. If they were done something like that, it should affect in-game all what is related with the flight, in the same way: take-off, landing, cruising... and level bombing.
But if you hit the Autopilot during one of your bombing missions, and then watch how the AI does the task, you will see it is not able to perform a decent level bombing, even an AI pilot with the best skills.

IMHO, many improvements were introduced since the 4.09 patch until today: FM, beacons, temperatures, winds... And it seems something was missed or forgotten about level bombing and bombsights, along the patches.
The fact is neither the Norden/Lofte type BS nor the OKPB-1 type work as it is supposed to do... as if they were uncalibrated.:rolleyes:

Thus, IMO, if I must do calculations by myself to get certain accuracy, then I prefere to calculate directly the BS elevation angle for manual drop, instead of calculating how to compensate for a poorly calibrated automatic bombsight.


Anyway, if you can, please let me know what you find out using an E-6B on an ISA neutral map. I am curious about that.

As I said earlier, and as I've said in every post of this thread, I've tested many maps, with all the actual level bombers, at diffeerent altitudes. Taking in account the historical accuracy of pin-point high level bombing during the WW2 (less than 20% of bombs fell on their intended targets along the war), I've obtained a more than acceptable accuracy, always using manual targeting.
The most of data for my calculations were gathered in-game: altitude, IAS, heading, OAT. And, with the B-25J, the TAS was read, not calculated.

My tests included:
1) The lapse rate of OAT measured with different OAT gauges (The ISA model was confirmed in-game for all the tested maps).

2) The TAS regarding OAT and altitude (This was calculated with the E6-B and with the ISA equations, and measured with the TAS gauges of Me-262 and B-25J. Measurements match calculations, for different maps).

3) The accuracy of level bombing using manual targeting, in differents maps with all the bombers, but with no wind.

4) The accuracy of level bombing using manual targeting, in differents maps with all the bombers, but with winds: tail wind, nose wind, cross wind, any wind direction and any wind speed. (This confirms: the need of to calculate the Ground Speed and True Heading to mantain the True Course approaching to the target; the need of to use the + or - side slip angle of the bombsight to compensate the angle between True Course and True Heading; if not, the bomb will fall far from the target confirming the effect of the cross wind on the free fall bombs. True Heading, Ground Speed and Compensation Angle were calculated with the back side of the E6-B).

The atmosphere now is better mdeled, but humidity and true altitude are not included (by now). Anyway the atmospheric model involves the aircrafts' behavior: take-off, landing, flight, engines heating and endurance, max payload, speed, fuel consumption, trimming, altitude to engage/disengage superchargers, altitude to change the air/fuel mix... and a long etc.:cool:

Would you like to see one more test with the Gulf of Finland_summer map, anyway?
OK: when I return home next week, I'll do that test, and then I'll try to do a .ntrk to show how accurate may be the manual targeting.:cool:

[FrankB]

Hello Soldier_Fortune,

I am trying to find the formula IL2 uses for TAS calculation.

I spent the whole morning searching and reading the web and so far I can calculate temperature, pressure and density at the altitude, but I found no equation which would plug these to the TAS calculation.
(They always included other factors which circularly used TAS for their calculation)

Based on you example:


With your 2nd equation, TAS = 349 km/h
With an E6-B, TAS = 320 km/h
With the published IAS/TAS chart, TAS = 332 km/h
With ISA equations: 319,5 km/h


I suppose you have the ISA equation for TAS handy?
Would you be so kind and share it?

[Soldier_Fortune]

Hi FrankB. :)

Yes: I use ISA for all my above calculations, because the E6-B Flight Computer is based on that standard and, as far as I can see, also the atmosphere model in IL2 is based on ISA.

The equation to calculate manually TAS is:

TAS = IAS* SQRT(AD@MSL / AD_ALT) [1]

Where:

AD@MSL: Air Density @ MSL = 1.225 kg/m3
AD_ALT: Air Density at a given altitude

Surely already you've found the AD_ALT equation. But if not, that is:

AD_ALT = AD@MSL* [(Tmap - ALT*0.0065)/Tmap]^4.25 [2]

Where Tmap is the outside air temperature @MSL of the chosen map.

If you combine both equations, you can calculate TAS directly as an E6-B does it:

TAS = IAS*[Tmap / (Tmap - ALT*0.0065)]^2.125 [3]

WARNING:All the above temperatures are expressed in Kelvin (ºK = ºC + 273), and altitudes in meters. If you prefer to use feet for altitude, then you must change 0.0065 for 0.002 in all the above equations.

The eq. [3] clearly shows the link among TAS, IAS, actual altitude, and OAT at such altitude.
Being (Tmap - ALT*0.0065) the OAT at a given altitude, the eq. [3] allows you to calculate TAS directly with your altitude, speed and OAT gauges readings. And the best is that you can use any speed units: km/h, m/sec, MPH or knots, without a previous conversion. :cool:

I.e: The "Betty's" altimeter returns the altitude in meters but the IAS is read in knots (the G4M1-11 has an OAT gauge but it doesn't work; therefore you must calculate OAT by yourself... but you know how to do it.:D).
No problem: use altitude and IAS into eq. [3] as you read them..!:cool:

I hope this help you. Anyway, don't hesitate to ask me. :wink:

[FrankB]

Thanks Soldier, you are da man!.

The math is quite simple once you have the missing link, which, for me was your equation [1].

Reviewing my research I saw the equation before, but

In a different form: TAS = EAS*SQRT(AD@MSL / AD_ALT) and then the definition of EAS introduced dynamic pressure or Mach number and I never got results at least close to yours.
With a remark it is valid only for low-speed flight (~0.3 Mach)

[Soldier_Fortune]

Hi again!:grin:

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. :wink:

[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 :)





.

[Soldier_Fortune]

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

Hi J_W!:smile:

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. :mrgreen:

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. :rolleyes:

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

[Soldier_Fortune]

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.





.

[Soldier_Fortune]

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. :grin:

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

[Soldier_Fortune]

Hi again J_W. :grin:

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.
...



I suggested you to use the "in-game (onboard) clock" by a technical reason which surely you know.

Simulators must perform many calculations by time unit, being this time unit the frame out of a given fps rate. Normally 30 fps is a good choice... but it depends on the platform's power and quality.

IL-2 is not a "professional simulator" built with specific hardware and software, but a game to be used with home/general purposses computers. Also this simulator must admit to be played on-line among several players.
Considere that the first sim of this serie was IL-1 Sturmovik (released at Xmas. 2001): you can read its minimal and recomended reqieriments in Wikipedia... if you can keep from laughing (Damn it..! Surely your today's smartphone is more powerful than those computers...!:mrgreen:).
Therefore we are talking about a game which is 12 years old!
Since IL-2 Forgotten Battles (March 2002), the game has been improved with a great amount of expansions and patches... But probably the game's engine remains untouched since 11 years ago.

One only and dedicated computer might be tuned to gives the best visual outcomes in real time while it runs a sim. But it is more difficult to obtain identical outcomes with a wide variety of computers models and performances.

Imagine that you and me are playing a cooperative bomb run on-line; you are the flight's leader an I'm your wingman. We're flying He-111 with the same payload (i.e., a 1600 kg bomb). Both have the same keyboard's stop watch to measure the elapsed time between the drop and the hit. But you have a high performance computer (where IL-2 runs like a silk), and the mine is a crap where IL-2 runs choppy (almost like a slide show).
Both will release our bombs simultaneously at your command, and our stop watches are programmed to start when the the bombs are being released.
Your computer runs the sim at 30 fps, but the mine runs it at 20 fps.
Thus, probably you'll see both bombs hitting the ground at the same time and you stop your watch at that instant.
At that instant I already am seeing both bombs falling and my stop watch still is running. Finally, I'll stop it when I see both bombs hitting the ground.
Obviously, when we compare our respective stop watches readings, surely we see a difference of several seconds between them.
But I'm pretty sure that we must have identical readings from our respective "in-game/on-board clocks".

Corollary: Into "IL-2 world" all the clocks are sincronized and the events must be seen at the same time by any "internal" observer (player), regardless of the computer's quality each one uses.

But the observers live in the real world. So: How are the time inconsistencies between both worlds solved?
With a lag for the slowest observer's computer.

This is why I suggested you to measure times with the on-board clocks. Your stop watch or the internal clock are fine and very accurate... but they belong to the real world, not to the "Il-2 world".

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.

About this matter...

During my tests I performed the following experiment with the Russian bombisght to see diferences of settings between the usual inputs, and those for manual targeting.
The tests were done with and without wind: without wind I used TAS and altitude as usual inputs, and with wind I used GS and altitude.
For manual targeting I calculated the BS_EA (Bombsight Elevation Angle) using the classic equations for parabolic motion.
As you know, in the OPB-1 the usual inputs are processed by the BS and the outcome is an elevation angle indicated by its triangular marker.
The BS-EA for manual targeting must be set with the hollow marker.
If everything worked well, both markers should match.
But I observed that the calculated BS_EA, for given TAS and altitude, was greater than that set in the normal way. ALWAYS.
Without wind the difference was around +3º.

I used the ring target (object #181 in the FMB) as target and I've got hits inside the ring with manual targeting.
What if I had used the usual settings?
Surely my bombs would fall long, as you know.
Why?
Because the aiming angle obtained with usual settings is less than the needed and, therefore, the bombs would be released later.

Why the German bombs fall short?
There is not problems with German bombs. In fact, the same happens with American an Japanese bombs (the latter only when the bomber is a 'Betty').
And it happens because German, American and G4M11 bombers share the same type of bombsight: the Lofte/Norden type.

With these bombsights, the same experiment described above can not be done . But I guess that they share the same algorithms.
Leaving aside the Lofte/Norden BS is designed for auto targeting & drop, and the OPB-1 is not, what other difference between both types we could see?

Well... In the OPB-1, when you increase the elevation angle, the marker moves counterclockwise. In the Lofte/Norden occurs the contrary: the marker moves clockwise.

Probably those algorithms don't calculate angles, but values which represents angles on the screen. And perhaps somebody has forgotten to include a (-1) factor somwhere in those algorithms, to distinguish between one type of BS and the other.
Therefore, the Lofte/Norden has the same error than the OPB-1... but the Norden/Lofte should adds that error with the contrary sign than the OPB-1, because its angles scale is inverted.
Thus, the outcome is a greater elevation angle than the needed, which produces an earlier drop, and the bombs fall short.

I must repeat again: the Laws of the Mechanics work correctly in IL-2. The failure is in the bombisghts, and perhaps they should be reviewed and reworked by TD.

Of course, each player is free to experiment better ways to achieve the best accuracy for precision bombing from high altitudes, or to correct externally the actual issues about bombsights. But he shouldn't miss this concept: The simpler the better.:cool:

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

Yeah... I know that feeling. :(

See you soon! ;)

[KG26_Alpha]

IL2 1946 is not 12 years old, the game engine had a major overhaul at least twice since its original release that I can remember, probably more.

Anyhow...................

As I had a small amount of time to test today I did some work in the Lofte bombsite and made perfect drops.

Still working on Russian Bombsite..............

True Altitude calculation is needed.

He111 H6 2 x 500kg

Field Temp : 35
Field Alt : 30m
Ind Alt : 4000
OAT: -2
IAS : 270
TAS: 340
TA : 4150m

Now direct hits for German Bombs precisely where they are calculated and aimed using TA




















.

[Soldier_Fortune]

...
As I had a small amount of time to test today I did some work in the Lofte bombsite and made perfect drops.

Still working on Russian Bombsite..............

True Altitude calculation is needed.

He111 H6 2 x 500kg

Field Temp : 35
Field Alt : 30m
Ind Alt : 4000
OAT: -2
IAS : 270
TAS: 340
TA : 4150m

Now direct hits for German Bombs precisely where they are calculated and aimed using TA
[/COLOR]

:rolleyes:

This could be the answer to the question with which I opened this thread. But we must be cautious.

Some remarks:

- For an OAT = -2ºC @ 4000 m, the OAT @MSL should be 24ºC. In the vanilla version there are only 2 maps that meet that condition: Kuban and Bessarabia. And there is not maps with 35ºC @ MSL. So I assume you've used one of those maps, or any map of 25ºC (the difference of OAT at 4000 m would be negligible anyway).

- It seems you are repeating some of my tests, and extracting the same conclusions than me. But also you should test if for you TALT works with other very different maps (i.e.: Gulf of Finland_winter -20ºC @MSL and flying at altitudes above 5000 m). As far as I tested, TALT doesn't confirm that outcome with colder maps.

- "Target or miss" may be defined in many ways. "Target destroyed" may be one way. "Hit at less than xxxx meters" may be other. I don't know what you're using, and it is important to know if we are describing results in the same way. In my tests I used the ring target and considered "target" any hit within the limits of the external ring. Sometimes I've achieved direct impacts in the centre of the ring... but I considered them as a part of the "good luck factor".:grin:

- BTW, also I was testing the blast radius of different Russian bombs, and it seems they are well modeled. Is far as I can recall, a pair of 100 kg bombs have a blast radius of 40 m; a pair of 250 kg, around 80 m; a pair of 500 kg, around 120 m; a 1000 kg bomb, 140 m; a 1500 kg, around 200 m. More tests are needed with these and other bombs; but I think the blast radius are close to the real. All tests were made in open and flat terrain, using Willys as targets, covering a square of 200 x 200 m. I discovered a curious effect: sometimes some nearest target was not destroyed, while the farest were KIA... like if certain random effect appears.:rolleyes:

Please: Carry on some tests with colder maps to see if the TALT works for you, and let me know your data and outcomes.;)

[KG26_Alpha]

I'm spending no more time on it.

There's enough data here to have TD make changes.



:)

[Soldier_Fortune]

...

There's enough data here to have TD make changes.



:)

Really...??:confused:
I'm seeing no posts in this treath of any TD member till now.
So, I don't know if they are interested to solve this issue.:rolleyes:

[KG26_Alpha]

Really...??:confused:
I'm seeing no posts in this treath of any TD member till now.
So, I don't know if they are interested to solve this issue.:rolleyes:

:)

Perhaps direct this thread into the bug report v4.12.2 sticky.

[KG26_Alpha]

Really...??:confused:
I'm seeing no posts in this treath of any TD member till now.
So, I don't know if they are interested to solve this issue.:rolleyes:

Check your PM box :)

[KG26_Alpha]

Really...??:confused:
I'm seeing no posts in this treath of any TD member till now.
So, I don't know if they are interested to solve this issue.:rolleyes:

Jeremiah_Weed
&
Soldier_Fortune

Check your PM boxes :)

[Soldier_Fortune]

Thank you, KG.
I did read it! :grin:

[FrankB]

Hi Soldier Fortune,

I did some tests using your formula to calculate TAS, but I still seem to have unsatisfactory results on winter maps.
In the past weeks I have learned how to use FMB to create custom mission for testing.

Test environment:
- stock 4.12.2
- SB-2, 100% fuel, 6x100kg bombs
- altitude 2000m
- IAS 330km/h
- bullseye placed at 0m elevation on the shore to simplify the calculations
- no wind on the maps
- coming in from the water

Calculations:
- got TAS from IAS and ground temperature as per your equation
- got the bombing angle using the calculated TAS and altitude

Results:
- good hits on the Crimea map (at least one bomb landed within the pattern)
- bombs fell short on Moscow winter map by at least 3 patterns

So some other variable comes to the play when calculating the bombing angle - maybe the air density/resistance...

[KG26_Alpha]

Work is in progress on the bombsites for 4.13

[Soldier_Fortune]

Hi FrankB!

So some other variable comes to the play when calculating the bombing angle - maybe the air density/resistance...

As far as i could test and see, no ballistic affects are modeled for the bombs within IL-2, and their motions my be described through the Laws of Newton.
I've made a set of charts (attached to post #30) for "fixed angle bombing" based on those laws, and I'm achieving good hits with them.

Test environment:
- stock 4.12.2
- SB-2, 100% fuel, 6x100kg bombs
- altitude 2000m
- IAS 330km/h
- bullseye placed at 0m elevation on the shore to simplify the calculations
- no wind on the maps
- coming in from the water

For these data, using the OPB-1 chart and an E-6B, I got the following settings:

Moscow winter: OAT@GL = -17 ºC
OAT @ Flight Altitude = -30 ºC
TAS = 340 km/h
BS Drop Angle= 44º [This value is affected by the interpolation while the chart is being read, and the player's judgement about the angle setting for the bombsight: the OPB-1 can be set with a precision of 0.25º/keystroke (it means: you need 4 keystrokes to increase or decrease the BS angle by 1º)].

I'll test them tomorrow, flying a SB-2, and then I'll tell you my results.

Results:
- good hits on the Crimea map (at least one bomb landed within the pattern)
- bombs fell short on Moscow winter map by at least 3 patterns

OK: your tests with the Crimea map are consistent with your data above.
But... How did you got "0 m ground altitude and shores" in the Moscow map?:rolleyes:
In the Moscow map the ground is mostly flat... but the average ground altitudes are about 400 @MSL. If you've considered too low altitudes in your calculations, it may explain why your bombs fell short.

Let me give you some tips about level bombing:
- As lower is the chosen altitude for level bombing, as worse is the accuracy.
A good altitude is above 4000 m. Think like a bombardier: if you must carry on a pin point bomb mission flying at low altitude, it is better to use a bomber designed for such class of missions; e.g.: a Pe-2 or an IL-2.
Level bombing doesn't allow evasive maneuvers while you are flying the last leg of your bomb run. Therefore, if you are flying too low following a foreseeable path, you will make happy the flak crews. :mrgreen:

A difference of 100 m @ MSL within an altitude of 2000 m, means an altitude error of 5% and 2.5% for the distance. The same difference of 100m, but within an altitude of 6000 m, gives an error of 0.85% for the distance.

It is easy to check the altitude for airfields: you only need to place a plane on the ranway of the targeted A/F, while you're designing your mission with the FMB, and read the altimeter. But it's more difficult to know the GL altitudes for other targets.
This other reason to bomb them from higher altitudes, to improve the chances to hit them.

- Don't use the Speed Bar data as inputs to set the bombisght.
The Speed Bar readings are less accurate than the gauges readings, with the sole excepcion of the Heading.
Speed Bar gives IAS and ALT in steps of 10. It means that you could read 230 km/h in the Speed Bar, but 239 km/h in your IAS-meter. What is true? The latter. For altitude, a difference of 10 m is negligible. But a difference of IAS = 9 km/h, it's not.

I hope these tips will help you to improve your enjoyment.:cool:

[FrankB]

But... How did you got "0 m ground altitude and shores" in the Moscow map?:rolleyes:

In the Moscow map the ground is mostly flat... but the average ground altitudes are about 400 @MSL. If you've considered too low altitudes in your calculations, it may explain why your bombs fell short.


It is a known thing that water in IL2 has to be at 0 altitude, hence my choice to put the targets adjacent to the water surfaces.
On the Moscow map it is not a seashore, more like a river bank, but the altitude is still 0 (landed on the target marker just to be sure.)


- Don't use the Speed Bar data as inputs to set the bombisght.
The Speed Bar readings are less accurate than the gauges readings, with the sole excepcion of the Heading.
Speed Bar gives IAS and ALT in steps of 10. It means that you could read 230 km/h in the Speed Bar, but 239 km/h in your IAS-meter. What is true? The latter. For altitude, a difference of 10 m is negligible. But a difference of IAS = 9 km/h, it's not.


Yep, that is what I do since I fly mostly with speedbar off.
But one has to mention that the gauges are often unreadable - either blurry or the ticks are crammed together so sightly that it is hard to read exact value - that is why I chose SB-2 - as it was added recently, the gauges are more readable.


I hope these tips will help you to improve your enjoyment.:cool:

Good tips there!

[Soldier_Fortune]

Hi again FrankB.

I was reviewing the equations, and it seems the Air density calculation is wrong.

It's rare, because they are the ISA (International Standard Atmosphere) ones. But it would be possible.

The formula I've posted has given you a TAS = 367 km/h, right?
I've calculated TAS = 340 km/h with an E6-B, and I confirmed this result with an app for Android which I have.

It would explain why your bombs fall short: calculated TAS is greater than the real, and therefore the calculated drop angle also is greater by about 2 or 3º. Finally this angle causes that you drop your bombs too soon, missing the target.

Please, use the following equations:

- Pressure at bombing altitude:

P = 101325*[(Tmap-0.0065*ALT) / Tmap]^5.25

- Air density at bombing altitude:

AD = 0.0036*[P/(Tmap-0.0065*ALT)]

The temperatures must be converted into Kelvin before they're used in the equations above (T+273).
The pressures are given in Pa (Pascals).

These equations are also from ISA and I've checked them right now.

For your data:

Tmap = -17 ºC = 256 K
T @ 2000 MSL = -30 ºC = 243 K
Po = 101325 Pa
P = 77071 Pa
AD = 1.142 kg/m3
AD_std = 1.225 kg/m3

Then:

TAS = IAS * SQRT(AD_std/AD) = 330 * SQRT(1.225/1.142) = 342 km/h

With this TAS your drop angle should be right.

Please: test these equations, and let me know how they work for you.:wink:

[FrankB]

The formula I've posted has given you a TAS = 367 km/h, right?
I've calculated TAS = 340 km/h with an E6-B, and I confirmed this result with an app for Android which I have.


Right.


- Air density at bombing altitude:

AD = 0.0036*[P/(Tmap-0.0065*ALT)]


While your formula works ingame, this does not seem to compute the correct density according to the ISA tables (at 11000m it should be 22632 Pa), so I used the source formula

AD = (P*M)/[R*(Tmap-0.0065*ALT)]

where R and M is universal gas constant and molar mass of dry air and that gives me the constant 0,00348, giving same results as ISA tables.


Please: test these equations, and let me know how they work for you.:wink:

Your equations (and my slightly altered one) were spot on on both test scenarios as defined above.
I also tried to increase the altitude to 5000m as you suggested before, and at least one of the bombs was still hitting the target pattern. Great!

...until I switched from SB-2 to Ju-88 or B-25.
On both maps and both altitudes the bombs fell always short. Too short. Maybe 2-3 bombsight degrees.

[Jack_Aubrey]

Have you seen the new videos from 4.13 updates???? i think for us bombardiers it's a must seen .....

[Soldier_Fortune]

...until I switched from SB-2 to Ju-88 or B-25.
On both maps and both altitudes the bombs fell always short. Too short. Maybe 2-3 bombsight degrees.

This has nothing to do with the equations, but with the plane's attitude.

Both, B-25 and Ju-88, tend to sink more than other bombers. Therefore, when you engage the Level Stabilizer, automatically the plane will increase the Angle of Attack (AoA) trying too keep the altitude while damps the sinking.
This action avoids the bomber flies leveled, even if the level indicator and the variometer indicate that, and thus the bombisght is aiming to certain forward angle by default. You should substract this angle to that you've computed for a manual drop.

I've found that forward angle is about +3º when the Level Stabilizer is engaged and it is combined with fully trimmed elevator. For other elevator trimming, this angle would be a bit less... but I've not found an "universal" linear ratio for this matter. Too many variables are involved: TAS, altitude, payload, wind...
Therefore it's all about how well the player knows his plane's behavior at different speeds and altitudes under different external cirumstances, how well skilled he is to fly it using the proper trimming, and his jugdement about what is the actual AoA.