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