FMB / Mission Speed Bug

[Tolwyn]

Ok. My one question to IC/TD is this.

What is up with Speed in the FMB?

Can anyone give a CLEAR. CONCISE. ANSWER, please?

Here's my original post on this matter, and then a followup link to a forum post by someone with the same concern.

Is the Speed in the FMB IAS or TAS? Is this correct when flown by Human or AI?

I can't imagine how old this bug is.
PLEASE PLEASE take a close look at this. I normally wouldn't plead, but this is... important.

This centers around whether the flight is flown by AI or Human (in either SP or COOP mode).

Let's look at a typical line of waypoint information in a Mission file:

NORMFLY 7500.00 10000.00 6000.00 428.00 &1

The first value is the East/West coordinate. (in meters)

The second value is the North/South coordinate. (in meters)

The third value is the altitude (ALWAYS in meters). (in meters)

which leads us to

the fourth value is SPEED (ALWAYS in kph)

However, if it's a HUMAN controlled plane, this value is:

The TRUE AIR SPEED (TAS) given the Altitude... the speed your plane is at when you spawn in is IAS.

if you fly Imperial: 482 = about 190mph IAS @ around 20,000feet (6000m)
if you fly Metric: 482 = about 306kph IAS @ 6,000m

With me so far?

If you are the HUMAN in this flight, you spawn in the game travelling at 190mph or 306kph.

If the flight is an AI flight (or if the pilot is AI), the aircraft spawns in attempting to fly at the LITERAL value in the mission file (266mph (482kph)!!)

Can we fix this please? For mission planning and timing, etc.?

The game doesn't translate speed for AI flights the same as it does for Human flights based upon the values in the MISSION file.

[Tolwyn]

Here is a great post that also is also discussing the question:

http://www.mission4today.com/index.p...=180355#180355

[Marabekm]

As far as I know, yes speed is in kilometers per hour.

The AI will always fly at the speed you have them set to in the waypoint. So if you set it to 100 kph or 500 kph the AI will fly at that speed.

The players aircraft, the mission builder has 0 control over what speed they fly to be honest. Because the AI will fly at the set speed but maybe I want to fly max throttle, or I want to fly 60 throttle or whatever. But you would have no control over how fast I wanted to go.

[Tolwyn]

No you missed what I said I'm wondering if it's in true AirSpeed or indicated AirSpeed because I'm getting different results each time I try it. I know that it's in metric km/h but the question I have is whether or not it is consistently true AirSpeed to the ground or indicated AirSpeed by altitude.

[dimlee]

Just as a side note.
I tested Bf 110D recently in long flights over the sea and discovered something I never noticed before. When IAS remains constant, let's say exactly 380 kmh, TAS fluctuates a lot, for example, from 413 kmh to 419 kmh. No changes in altitude. Both readings are from screen indications.

[Marabekm]

Originally Posted by Tolwyn

No you missed what I said I'm wondering if it's in true AirSpeed or indicated AirSpeed because I'm getting different results each time I try it. I know that it's in metric km/h but the question I have is whether or not it is consistently true AirSpeed to the ground or indicated AirSpeed by altitude.

Oops, I see what you are asking now. Perhaps try this to find out:
Set a multicrew aircraft to spawn in at lets say 300 kph, or whatever you want. Then you pick the gunner seat and hit fly. Since you are not the pilot, the plane is technically AI. See if what your speedbar is saying is what you set (IAS) or maybe if its a lower than what you set, in which case it would be (TAS)

My test: A group of B5N2's. In the mission builder I have speed set to 259 kph. Altitude of 3000 mters. Ok now I fly the mission but I do not pick the pilots seat, instead pick the bombardiers seat.

After doing this test, I believe it is Indicated Airspeed or IAS
My speed bar when I spawned in was alternating around 250 to 260 kph. And the gauges in the aircraft were reading around 135 kts.

Now if it was TAS, when I spawned, the speed bar should have been around 210 to 220 kph (110 to 120 kts on the guage) at my altitude of 3000 m.

[Tolwyn]

Ok. Thanks. I'll keep messing with it.

The speeds are definitely different if:

1. Spawned in a Human Flight
2. Spawned in an AI Flight
3. Spawned in an AI Pilot with Human (multicrew)

Maybe need some info from TD on how planes are spawned in; regardless of initial WP settings.

It's not a horrible bug (my first post seems a bit dramatic now), but just... you know, inconsitencies bother me.

[Soldier_Fortune]

Hi all, mates!

It is advisable that since the patch 4.11 each map has its own Ground Level Temperature.

This was done for to model the engine's berhavior regarding the temperature, for a more realistic "complex management" of each plane. Also, the speed and direction of speed of wind may be chosen in the FMB.

So, since 4.11 the atmosphere properties in the "IL2 World" is a bit closer to the the atmosphere of the real World.

But this complex manegement is extended to the plane's Air Speed too:
- The air density decreases with the altitude; so the TAS increases proportionally with the altitude.
- But the density of the air increases the lower the temperature, so the TAS decreases.
- The gradient of temperature, according to International Standard Atmosphere, is -6.5 C per km of altitude.

The calculation of TAS now is a complex task for us, because all the IAS-TAS conversion tables previous to 4.11, were done for other "IL2 World", where the temperature was 0 C for all maps at any altitude, being those tables unuseful today.


I use a real E6B Flying Computer (the famous Wizz Wheel) while I'm flying, as well as for to design my missions in the FMB. The E6B calculates the TAS for a given IAS, altitude and outside temperature: all these needed inputs may be read in the respective gauges.

There are several free "E6B emulators" for smart phones: if you are interested , look for them in Play Store.


As far as I could see, the planes try to fly at the planned IAS, up to the limit of their max designed IAS. It can be tested with any plane.

I suggest you the following test:

Fly the Me-262, because its speed gauge indicates IAS (the white needle), and TAS (the yellow needle), with the speed in km/h; fly in different maps but at the same altitude: you'll be noticed about the difference of TAS for each map. The cons of the Me-262 are this plane doesn't have an "Outside Air Temperature" gauge.

Or, alternativelly, fly a B-25J: it has in the bombardier cockpit a temperature gauge, an altimeter and an IAS-TAS gauge. The cons: the altitude is indicated in feet and the air speeds in MPH.

In both cases, for this test purpose, you can design a simple mission with the FMB only ane human pilot, indicating waypoints with reasonable speeds, from take-off up to a given cruising altitude.

Then, Fly the mission hiting de "Autopilot" key, and let the AI to command your plane: you only need read the gauges, and to check if your readings are according to the "E6B calculations".

I hope this comments may help.

S!

[stugumby]

ju88 bombsight has tas gage on it as well, when in doubt use the wonder woman gage and input to nearest 5 kph.