Work out TAS from meters? For bombing

[mcler002]

Hey sorry if this is a double post

I need someone to tell me how to work out:
1. IAS (in mph) to TAS
2. IAS (in kph) to TAS

Also need someone to explain the he 111 bomb sight

Cheers

[Blackdog_kt]

For IAS/TAS conversion you need to know the outside temperature and altitude.

There is however a rough, rule of thumb conversion available that's accurate enough for our flight simming. For every 1000ft (that's about 330m), add 2% of IAS.


Example for imperial units:

IAS is 200 mph at 25000 ft

2% of 200 mph is 200*0.02=4mph

(It's easy enough to calculate the 2% while you fly, just divide your IAS by 100 to get the 1% and multiply it by 2, in this case 1% of 200 is 2, so 2% of 200 is 4)

25000ft/1000ft = 25 times a thousand feet

The value to add is then 25*4=100 mph

Hence, TAS = IAS + 100mph = 200 + 100 = 300 mph.

Examples for metric units:

Since we know we need to add 2% on top of IAS for every 1000ft, we can convert this to meters.

A km is roughly 3000ft, 500m is roughly 1500ft and we now the 2% per 1000ft rule.

So the % we need to add for those values is respectively three times 2% (that is 6%) for the km or 1.5 times the 2% (that's 3%) for 500m of altitude.

So, let's say i'm in a 109 cruising at 5000 meters and 350 km/h.

1% of 350 is 3.5 km/h
5km/1000 meters = 5
So, the value to add is: (6% per thousand meters) * 5 = 6 * 3.5 * 5 = 105km/h

And TAS = IAS + 105 = 350 + 105 = 455 km/h


Alternatively, we could use the 3% per 500 meters rule and get the same result:

5km/500 meters = 10
1% of current IAS = 3.5km/h
Value to add: (3% per thousand meters) * 10 = 3 * 3.5 * 10 = 105 km/h again

and TAS is the same as in the previous example: 350 + 105 = 455km/h

The only reason i'm giving two methods here is that a km is about three time a thousand feet and maybe you need more accuracy.

Alternatively, you could also use the 2% rule per 1000ft for metric units too, just keeping in mind that 1000ft is roughly 300 meters (330 something actually).

This would allow you to keep things simpler by having a single % rule in mind, but you would get your TAS in increments of 300 meters.



There is also a conversion table for imperial and metric units on pages 111 and 112 of the manual respectively.

You can find the PDF manual in your game folder, under the steam folder:
C:\Steam\steamapps\common\il-2 sturmovik cliffs of dover\manual



Finally, the German Lofte bombsight allows you to calculate TAS by making adjustments on the fly and seeing if the sight can track a target on the ground. You just input a ballpark estimate value and fine-tune it from there.

There is currently a bug with the Lofte sight that has been reported and we're waiting for a fix in the next patch. The sight tracks correctly when using metric units. However, the release point is calculated wrong because the code that calculates it treats the speed you input as mph.

This means you currently have to choose between having the sight track correctly and adjusting the aim point to account for the release point error, or you can have the sight track incorrectly but calculate the correct release point.

Most people choose the second option. What you do is convert your TAS from km/h to mph:

TAS in km/h = (TAS in mph) *1.6
Hence, to convert to mph we do the opposite and divide: speed in mph = (speed in km/h) / 1.6

You input that speed on the sight and your altitude above ground, place the sight crosshairs on the target and engage bombsight automation.

The sight's aiming point will drift because it uses the correct speed units (it treats the numbers as km/h), but for each of these aiming points the release point calculated will be correct.

What you do then is to disengage automation, move the crosshairs back on the target and re-engage it. You do this 3-4 times as you get closer to the target until you are right on top of it and the bombs will release more or less correctly.



This here is an introduction and it might be too much to take in one read. The speed unit bug doesn't make things easier but it can be worked around while we wait for the patch.

Ideally, after the patch we'll have a corrected Lofte and you won't need to do any calculations at all, just adjust the sight until it tracks a single aiming point on the ground. For now though the above methods work.


There are also other things to keep in mind, like setting autopilots to fly the aircraft from the bombardier's seat and so on, which are covered in more detail in other posts (i will link them for you below).


Overall:

1) Read this post to get the general idea.

2) Check out the FAQ sticky here (describes the operation for a correct bombsight, just scroll down a bit as it contains other info too): http://forum.1cpublishing.eu/showthread.php?t=24782

3) Check out the dedicated He-111 thread where the speed unit bug and workaround are mentioned in more detail. This thread describes the operation for the bugged bombsight we currently have (credit goes to the people on the ATAG server for testing this and finding what's actually wrong with the sight):
http://forum.1cpublishing.eu/showthread.php?t=29453

4) Load up a He-111 in a QMB free flight mission and have a practice run to test things out. Keep things nice and easy to be able to judge your results. Cruise at 3km or so to make it easier to see your bomb impacts and attack an arbitrary point on the coast, so that you don't have to worry about the target's elevation.

The sight needs altitude above the target, not altitude above sea to work correctly, so attack something that's next to the sea to eliminate this variable from your tests.


5) Join the ATAG server and their teamspeak sometime during this weekend. You are bound to find at least a couple dedicated bomber pilots there that can gradually talk you through it all.

6) Have fun learning the ins and outs of the whole thing. It sounds awfully complicated but after you do it a couple of times it's not that big a deal ;)

[Meusli]

For IAS/TAS conversion you need to know the outside temperature and altitude.

There is however a rough, rule of thumb conversion available that's accurate enough for our flight simming. For every 1000ft (that's about 330m), add 2% of IAS.


Example for imperial units:

IAS is 200 mph at 25000 ft

2% of 200 mph is 200*0.02=4mph

(It's easy enough to calculate the 2% while you fly, just divide your IAS by 100 to get the 1% and multiply it by 2, in this case 1% of 200 is 2, so 2% of 200 is 4)

25000ft/1000ft = 25 times a thousand feet

The value to add is then 25*4=100 mph

Hence, TAS = IAS + 100mph = 200 + 100 = 300 mph.

Examples for metric units:

Since we know we need to add 2% on top of IAS for every 1000ft, we can convert this to meters.

A km is roughly 3000ft, 500m is roughly 1500ft and we now the 2% per 1000ft rule.

So the % we need to add for those values is respectively three times 2% (that is 6%) for the km or 1.5 times the 2% (that's 3%) for 500m of altitude.

So, let's say i'm in a 109 cruising at 5000 meters and 350 km/h.

1% of 350 is 3.5 km/h
5km/1000 meters = 5
So, the value to add is: (6% per thousand meters) * 5 = 6 * 3.5 * 5 = 105km/h

And TAS = IAS + 105 = 350 + 105 = 455 km/h


Alternatively, we could use the 3% per 500 meters rule and get the same result:

5km/500 meters = 10
1% of current IAS = 3.5km/h
Value to add: (3% per thousand meters) * 10 = 3 * 3.5 * 10 = 105 km/h again

and TAS is the same as in the previous example: 350 + 105 = 455km/h

The only reason i'm giving two methods here is that a km is about three time a thousand feet and maybe you need more accuracy.

Alternatively, you could also use the 2% rule per 1000ft for metric units too, just keeping in mind that 1000ft is roughly 300 meters (330 something actually).

This would allow you to keep things simpler by having a single % rule in mind, but you would get your TAS in increments of 300 meters.



There is also a conversion table for imperial and metric units on pages 111 and 112 of the manual respectively.

You can find the PDF manual in your game folder, under the steam folder:
C:\Steam\steamapps\common\il-2 sturmovik cliffs of dover\manual



Finally, the German Lofte bombsight allows you to calculate TAS by making adjustments on the fly and seeing if the sight can track a target on the ground. You just input a ballpark estimate value and fine-tune it from there.

There is currently a bug with the Lofte sight that has been reported and we're waiting for a fix in the next patch. The sight tracks correctly when using metric units. However, the release point is calculated wrong because the code that calculates it treats the speed you input as mph.

This means you currently have to choose between having the sight track correctly and adjusting the aim point to account for the release point error, or you can have the sight track incorrectly but calculate the correct release point.

Most people choose the second option. What you do is convert your TAS from km/h to mph:

TAS in km/h = (TAS in mph) *1.6
Hence, to convert to mph we do the opposite and divide: speed in mph = (speed in km/h) / 1.6

You input that speed on the sight and your altitude above ground, place the sight crosshairs on the target and engage bombsight automation.

The sight's aiming point will drift because it uses the correct speed units (it treats the numbers as km/h), but for each of these aiming points the release point calculated will be correct.

What you do then is to disengage automation, move the crosshairs back on the target and re-engage it. You do this 3-4 times as you get closer to the target until you are right on top of it and the bombs will release more or less correctly.



This here is an introduction and it might be too much to take in one read. The speed unit bug doesn't make things easier but it can be worked around while we wait for the patch.

Ideally, after the patch we'll have a corrected Lofte and you won't need to do any calculations at all, just adjust the sight until it tracks a single aiming point on the ground. For now though the above methods work.


There are also other things to keep in mind, like setting autopilots to fly the aircraft from the bombardier's seat and so on, which are covered in more detail in other posts (i will link them for you below).


Overall:

1) Read this post to get the general idea.

2) Check out the FAQ sticky here (describes the operation for a correct bombsight, just scroll down a bit as it contains other info too): http://forum.1cpublishing.eu/showthread.php?t=24782

3) Check out the dedicated He-111 thread where the speed unit bug and workaround are mentioned in more detail. This thread describes the operation for the bugged bombsight we currently have (credit goes to the people on the ATAG server for testing this and finding what's actually wrong with the sight):
http://forum.1cpublishing.eu/showthread.php?t=29453

4) Load up a He-111 in a QMB free flight mission and have a practice run to test things out. Keep things nice and easy to be able to judge your results. Cruise at 3km or so to make it easier to see your bomb impacts and attack an arbitrary point on the coast, so that you don't have to worry about the target's elevation.

The sight needs altitude above the target, not altitude above sea to work correctly, so attack something that's next to the sea to eliminate this variable from your tests.


5) Join the ATAG server and their teamspeak sometime during this weekend. You are bound to find at least a couple dedicated bomber pilots there that can gradually talk you through it all.

6) Have fun learning the ins and outs of the whole thing. It sounds awfully complicated but after you do it a couple of times it's not that big a deal ;)

Will the table converter from the old IL2 work in this game?

[mcler002]

Hey

I asked a question (related to my current bombing activities) on the thread Altimeter full real found in Technical threads/ Vehicle and Terrain threads

Cheers

[Blackdog_kt]

Will the table converter from the old IL2 work in this game?

If you mean the bombsight table program, it's made for the old IL2's atmosphere model, but i think it will give a close enough estimate. In any case you can fine tune your TAS by calibrating the bombsight (not possible in the non-auto sights, eg Blenheim and Br20, it works in the German Lofte though: get an approximate value and fine-tune).

The problem is that bombsight table has trouble running in windows 7: many people report it doesn't overlay above the game window as it should, but results in the game window minimizing completely.

[ATAG_Keller]

I've been using the HE111 level bombing with some success, check this thread to see how I do it.

http://forum.1cpublishing.eu/showthread.php?t=23048&page=2

To add to that post, here are more numbers that I have calculated, you still need to manually move the bombsight though.

Set your airspeed at IAS (I calculated it this way to remove one variable)

For 1000m set to 1400
For 2000m set to 3400
For 2500m set to 4200
For 3000m set to 4800