Why does nose drops after gear up?

[Bolelas]

I read that e.g., after take-off, when the landing gear is retracted the nose seems to drop. (i saw on a youtube video about a CLOD bf110 take-of) Why is that?
Whow about the flap changes, what do they produce on pitch attitude? Are they correctly moddeled in game? Other games moddeled they correctly?

[K_Freddie]

Could it be due to automatic flap retraction, when the gear is up and traveling over a certain speed. Also maybe a result of take-off elevator trim...

[Bolelas]

At first glance it seems wrong. But i read some article about a device (prototipe) to counteract this efect. So, it probably means this happens. (and i am not including flaps in it, this was second question)

"It is known that aircraft in flight, when lowering retractable landing gears in preparation for landing, experience a nose up condition."

I got it from here:http://www.google.com/patents/US3045954

It is the other way around, but samething. Thx for you answer Mr Freddie.

[MaxGunz]

When you speed up or slow down, your lift changes and you need to change pitch, maybe do that without thinking, but it's flaps that change your center of lift.

IIRC, CoL changes some with AoA.