Crossunder
19th Jun 2008, 16:15
Does anyone have a graphic presentation of the drag curves for a Boeing 737 at different altitudes/weights?
What I am looking for, is to see how the curve changes with an increase in altitude. Is the curve relatively flat at high altitudes (FL300-370)? Does it have a drag bucket? I have always thought that the 737 drag curve (high altitude) would look like a narrow U, or even V-shaped?
I frequently discuss cost index and Mach number with my colleagues when we are flying. Many pilots think that flying the B733 at M .73 (CI 14) causes the aircraft to encounter speed instability (the a/c somehow slows down, and tends to stay at the lower speed, causing the A/Ts to work constantly). They say the NG is more sensitive to this (CI below 20) than the CL. If the drag curve is "flat", this could perhaps explain it (if what they say were true...). BTW: These are usually the same pilots who talk about "getting on the step". I am also told that the B737 "flies better" at M .76 than at .737, whatever that means.
Personally, I think ISA deviation and CG location cause greater variations in drag and pitch attitude than does slowing from M .747 to .737-ish...
any thoughts?
What I am looking for, is to see how the curve changes with an increase in altitude. Is the curve relatively flat at high altitudes (FL300-370)? Does it have a drag bucket? I have always thought that the 737 drag curve (high altitude) would look like a narrow U, or even V-shaped?
I frequently discuss cost index and Mach number with my colleagues when we are flying. Many pilots think that flying the B733 at M .73 (CI 14) causes the aircraft to encounter speed instability (the a/c somehow slows down, and tends to stay at the lower speed, causing the A/Ts to work constantly). They say the NG is more sensitive to this (CI below 20) than the CL. If the drag curve is "flat", this could perhaps explain it (if what they say were true...). BTW: These are usually the same pilots who talk about "getting on the step". I am also told that the B737 "flies better" at M .76 than at .737, whatever that means.
Personally, I think ISA deviation and CG location cause greater variations in drag and pitch attitude than does slowing from M .747 to .737-ish...
any thoughts?