1C Home   |   Register   |   Today Posts   |   Members   |   UserCP   |   Calendar   |   Search   |   FAQ

Go Back   Official 1C Company forum > 1C Publishing > IL-2 Sturmovik > Daidalos Team discussions

Reply
 
Thread Tools Display Modes
  #1  
Old 09-17-2013, 05:17 PM
Soldier_Fortune Soldier_Fortune is offline
Approved Member
 
Join Date: Jan 2013
Location: Madrid, Spain
Posts: 68
Question True Altitude?

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.
Reply With Quote
  #2  
Old 09-21-2013, 12:30 AM
KG26_Alpha's Avatar
KG26_Alpha KG26_Alpha is offline
Super Moderator
 
Join Date: Jan 2008
Location: London
Posts: 2,796
Default

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.






.
__________________



Last edited by KG26_Alpha; 09-21-2013 at 12:35 AM.
Reply With Quote
  #3  
Old 09-22-2013, 08:08 PM
Soldier_Fortune Soldier_Fortune is offline
Approved Member
 
Join Date: Jan 2013
Location: Madrid, Spain
Posts: 68
Default

Quote:
Originally Posted by KG26_Alpha View Post
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.

Quote:
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.

Last edited by Soldier_Fortune; 09-22-2013 at 08:10 PM.
Reply With Quote
  #4  
Old 09-23-2013, 01:23 PM
KG26_Alpha's Avatar
KG26_Alpha KG26_Alpha is offline
Super Moderator
 
Join Date: Jan 2008
Location: London
Posts: 2,796
Default

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.



Also

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



Last edited by KG26_Alpha; 09-23-2013 at 01:43 PM.
Reply With Quote
  #5  
Old 09-23-2013, 08:23 PM
Soldier_Fortune Soldier_Fortune is offline
Approved Member
 
Join Date: Jan 2013
Location: Madrid, Spain
Posts: 68
Default

Quote:
Originally Posted by KG26_Alpha View Post
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.


Quote:
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. ... 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...

Quote:
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.
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.
Reply With Quote
  #6  
Old 09-23-2013, 09:51 PM
KG26_Alpha's Avatar
KG26_Alpha KG26_Alpha is offline
Super Moderator
 
Join Date: Jan 2008
Location: London
Posts: 2,796
Default

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.







.
__________________



Last edited by KG26_Alpha; 09-24-2013 at 11:41 AM.
Reply With Quote
  #7  
Old 09-24-2013, 04:06 PM
Soldier_Fortune Soldier_Fortune is offline
Approved Member
 
Join Date: Jan 2013
Location: Madrid, Spain
Posts: 68
Default

Quote:
Originally Posted by KG26_Alpha View Post
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.


Quote:
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.

Quote:
A word form TD would be enlightening.
+1.
Reply With Quote
  #8  
Old 09-24-2013, 07:08 PM
hafu1939 hafu1939 is offline
Approved Member
 
Join Date: Apr 2011
Posts: 24
Default

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.
Reply With Quote
  #9  
Old 09-25-2013, 03:01 PM
Soldier_Fortune Soldier_Fortune is offline
Approved Member
 
Join Date: Jan 2013
Location: Madrid, Spain
Posts: 68
Default

Quote:
Originally Posted by hafu1939 View Post
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.

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

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!
Reply With Quote
  #10  
Old 09-25-2013, 05:23 PM
KG26_Alpha's Avatar
KG26_Alpha KG26_Alpha is offline
Super Moderator
 
Join Date: Jan 2008
Location: London
Posts: 2,796
Default

I use Pilotwizz app on my Iphone
Attached Images
File Type: jpg pwizzJPG.JPG (99.2 KB, 16 views)
__________________



Last edited by KG26_Alpha; 09-25-2013 at 05:30 PM.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 05:16 PM.

Based on a design by: Miner Skinz.com

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright © 2007 1C Company. All rights reserved.