A lot of talk about `pitching` ;) Excellent explanation, Kittle.

Bolelas, you can find some nice general information here:
http://en.wikipedia.org/wiki/Propeller_(aircraft)

But...why would you want to increase speed in an attack dive? Its IMHO one of the Hs129s best features - beside the stable flight - that you have plenty of time for a proper attack. This is even more important with the BK7.5 version, where you can make up to 3-4 shots per attack.

Indeed! I throttle back before my attack dive in a Hs129. The aircraft is immensely stable thanks to the counter rotating prop design and it lets you get several shots on target with minor corrections to engage multiple tanks in those rare cases.

In other types you may want to increase dive speed although... sometimes not :) It's often fun to appear to be going fast but really you're wiping as much speed in the dive as possible and the other guy goes sailing past.