True Altitude?

[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.