Joined: Aug 23, 2005 Posts: 266 Location: On a course.... golf course
Posted: Mon Dec 19, 2011 3:09 am Post subject:
The parasite drag comes from the airflow blowing downwards over the fuselage. It adds to the apparent weight, so you need a little extra thrust to overcome it.
Looking at forward flight, you have four main vectors-
weight acts vertically down
"lift" acts vertically up to counteract weight (yeah, yeah, calm down, we all know it is perpendicular to the RAF, blah blah, just let me finish)
Drag acts backwards
Thrust acts forwards and is balanced with drag when at a constant speed.
As you slow down, and the downwash slowly changes from being rear-and-down to just being down, the vectors move around a little - lift and weight stay the same, drag moves to being a bit down, and thrust has to move a bit up.
In the hover, weight and drag coincide, and lift and thrust coincide, so in the hover you get
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