Small hint for formation flying / climbing with the P39 with sufficient speed to avoid AI flap usage

[kraut1]

Hi All,

only for information, maybe you all know:

Today I tested a new campaign P39 bomber intercept mission.

I had great trouble to get my flight of 4P39 in formation and to climb.

Although I used reduced manifold pressure (ca.30-32) and 2400 - 2600rpm after take off the flight, especially no. 3 and 4 had problems to follow me, especially when I climbed. They flew more and more slower. I repeated the mission 4 times until I succeeded.

When I watched the videos I noticed that they had extended their flaps.

Maybe a bit similar to formation flying issues I observed for other planes when they suddendly extended their flaps when flying a curve.

After the mission was tested I had a look to the AI file of the P39 and made a small test to deactivate flaps for most flight situations:

from:

to:

I flew a take of / climbing test and it worked.

 

But of course it is not a good idea to modify each and everything.

The climb speeds in the AI file are marked with //ToDo

 

And I had look in a manual of the P39D (not the L):

 

To avoid the Mod of the AI I made a new test without modification:

 

I took of without flaps comparable fast with ca. 140mph and accelerated at first to ca. 160mph. At this speed the flights no2, no3 and no4 were quick in the formation and when I climbed with ca. 155 to 170mph everything worked.

After that I tested what happens if I climb with a slower speed: when climbing with ca. 120-140mph (without flaps) my AI flight members extended their flaps, flew more and more slower and the formation was lost.

 

Conclusion:

This means that with the current AI formation flying and climbing works well with ca. 160mph and faster.

(And this speed uses AI with activated autopilot too)

But for other issues in formation flying and AI escort fighters with active "Cover", when they sometimes lower their flaps, a change of the AI with reduced "flap activation speeds" could be a solution.

 

 

Edited May 25, 2024 by kraut1