[MadBlaster]

Originally Posted by BlackBerry

MadBlaster, When your la7 diving at 20 degree with constant speed of 610km/h, the air drag force is completely counteracted by g*sin(20), and you turn on engine, so that you add extra thrust from engine, although the engine thrust is smaller than airdrag force, this is the excess thrust.

Both gravity---g*sin(20) and engine thrust are allied, the sum of these two, are counteracting against air drag force, since the sum of them is greater than air drag( at 610km/h), your la7 speed increases, when you reach 700km/h, air drag is quite more than g*sin(20), so a portion of engine thrust(eg 40%) will be used in completely 100% counteracting air drag. The excess thrust is from the left portion of engine thrust(60%). The more efficiency, the more excess thrust you get, understand?


If you dive at 60 degree angle reaching 700km/h, of course, your engine thrust could not 100% conteract the air drag by itself, so you need gravity--g*sin(60) to help you, if propeller efficiency is high, you need less gravity to help you, and more gravity will be used as excess thrust. if you turn off engine(efficiency=0), you need the most gravity to help, thus minimum excess thrust.

Therefore, excess thrust comes from the sum of gravity and engine thrust. Gravity and engine thrust help each other, this is teamwork, if one of them performs better, the other will have more ability to counteract air drag, Understand? The more propeller efficiency, the more sum, the faster dive.

yes blackberry. this example is rigged though. if i spawn from 3000 meters and V max with the engine off, I can also create acceleration or de-cceleration simply by changing the angle of the dive and the result is a new terminal velocity/equilibrium. it's the change in the sum of the two vector forces, not simply "the sum of" the two vector forces. the thrust vector is still zero in this case.

But we have been assuming up to now the engine is on, level flight and v max.