For the same thrust, a heavier plane would accelerate more slowly while stying on the same glide slope. Or isn't that what we are talking about? Are you saying the RoD would increase more quickly for a change in nose attitude, given that we are at max power?
I'm strictly speaking of descents at any power setting, as long as its the same between the lighter and heavier loaded plane.
Lets see if we can get on the same page with a few things....
-In an aircraft such as a 757, at a given thrust, wouldnt the airplane speed up as AoA decreases(nose down attitude)? And slow down as AoA increased?
-At a given thrust, wouldnt the airplane speed up as RoD increases? And slow down as RoC increased?
-All other factors being the same in an identical plane, wouldnt the heavier airplane have a top of descent(3X rule?) that is farther from the airport?(I'm almost positive of this)
Wouldn't what we are talking about be the opposite in a climb, theoretically?(This is where I may be wrong!!)
If you are saying a heavier loaded plane wouldnt accelerate as fast descending at a given rate(-2000 fpm) and thrust(say 50%), aren't you saying that it will decelerate less slowly while climbing as well? I know thats not the case and I can prove it by looking at some 757 performance charts, which I do have at my disposal.
What actually would happen, from a stick and rudder perspective, would be that to maintain the picture (fixed on the impact point of the Pentagon) of the glide in attack from 2000 feet to about 40 or zero feet, with fixed power, the pilot has to adjust the angle of attack with his nose to maintain the desired glide path. A heavier aircraft would, all other things being equal, be a few knots slower on that glide path due to needing the marginally increased lift to hold glide slope as constant.
Again, starting at the same point over the ground, about 4 nm away at 2000 feet, to hit a spot on the side of the Pentagon at "0" feet, you have to counter act the increased weight with a slightly increased lift to stay on glide slope, which means slightly higher nose attitude/angle of attack, which means slower airspeed. Trying to stay on identical airspeed with a heavier plane makes for, at identical power settings, a higher rate of descent. But the point is to hit the target.
I agree that a heavier airplane needs nose up correction to maintain RoD. I still think it speeds it however.
Can we agree that in a descent, given the same AoA/thrust, the heavier airplane will have a higher rate of descent, thus having a higher speed?
DR
DogTown said:
LC 23 comes out yesterday, and you guys are going on about thrust,lift etc..
Is this the sex, or DennyTario forum?
No Offense ment!
Hey now, some of find this boring sh[rule8] interesting!