Table 13: Ranking of Desirable features of pitch trim strategies.
Strategy |
Concept |
Cruise drag counts (Lowest) |
Angle-of-attack (Lowest) |
Central surface Deflections (lowest average of module) |
Linear aero-dynamics (Lowest α and lowest δ) |
Simplicity |
I |
Equal deflections |
766 (+97) (7th) |
1.8406° (2nd) |
1.7200° (2nd) |
6th |
1st |
II |
Deflection of elevator only |
551 (-18) (1st) |
2.0727° (3rd) |
10.36° (7th) |
7th |
2nd |
III |
Preferential inboard surfaces with 7.5º limit |
659 (+100) (untrimmed) (6th) |
0.71789° (1st) |
8.9798° (6th) |
4th |
7th |
Optimal Deflection |
IV – good start |
561 (-8) (untrimmed) (3rd) |
0.71789° (1st) |
-7.2529° to +7.4047° (5th) |
3rd |
9th |
V – bad start |
635 (+66) (untrimmed) (4th) |
0.71789° (1st) |
-3.685° to + 4.125° (3rd) |
1st |
10th |
|
VI |
Equal lift contributions from each surface |
1089 (+420) (9th) |
2.2794° (5th) |
2.7478° to 14.971° (7th) |
9th |
6th |
VII |
Multiples of optimal deflection |
635 (+66) (4th) |
3.1267° (6th) |
-16.002° to + 17.912° (9th) |
10th |
8th |
Direction of deflection opposite to drag slope |
VIII – constant AOA
|
651 (+82) (5th) |
0.71789° (1st) |
-2.8825° to + 24.727° (10th) |
5th |
4th |
IX – changed AOA
|
787 (+218) (8th) |
2.1313° (4th) |
0.0º to + 2.8588° (1st) |
8th |
5th |
|
X |
Selection of most effective control surfaces (1st) |
554 (-15) (2nd) |
0.71789° (1st) |
-8.6295° to + 3.7402° (4th)
|
2nd |
3rd |