final graduation

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This is my presentation for my final graduation, performed at the faculty of aerospace engineering at the Delft University of Technology. I will put the movies incorporated in the presentation on YouTube

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Challenge the future

DelftUniversity ofTechnology

Flight director design for zero and partial gravity flightSimulation analysis and experimental results of the partial gravity maneuver

Bram MasselinkDepartment of control and simulation Faculty of aerospace engineering

10-04-2023

prof. dr. ir. J.A. Mulderprof. dr. ir. M. Mulder

dr. ir. M.M. van Paassenir. A.C. in ‘t Veld

ir. M.H. Smaili

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Flight director design for zero and partial gravity flight

• A flight director is… • … an aid for a pilot ... • … on a display …• … to fly a certain maneuver.

• A zero or partial gravity maneuver is …• … a flight maneuver …• … in which during a short period …• … a sense of weightlessness or microgravity is experienced.

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Reasons to perform partial gravity flights

• Fundamental research• Practical research• Test space equipment before launching it

“To understand in full the mechanisms governing our life and physics, we need to study what life would be without

it (gravity, edit.)” 1

1 ESA, “ESA Research,” 2008, http://www.esa.int/esaHS/research.html

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FLIGHT DIRECTOR DESIGN FOR ZERO AND PARTIAL GRAVITY FLIGHT

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Contents

• Introduction• The parabolic flight maneuver• Reference frames and specific forces

• Design of the flight director control law and display• Experiment 1: flight simulator

• Method• Results

• Experiment 2: test flight• Conclusions and recommendations

introduction – FD design – simulator – test flight – conclusions

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Test facilities

• NASA Zero Gravity Research Facility, Cleveland, Ohio• 145m free fall tower (5.18s zero gravity)

• International Space Station (ISS)• ‘unlimited’ zero gravity

• CNES Airbus A-300 ZERO-G (15 – 20s zero gravity)• Cessna Citation II Laboratory Aircraft (TUDelft) (up to 10s

0g)

introduction – FD design – simulator – test flight – conclusions

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Parabolic flight maneuver

introduction – FD design – simulator – test flight – conclusions

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Earth vs. body fixed reference frame

Required specific forces in the body fixed reference frame:

λg = 0.00g (Space)λg = 0.17g (Moon)λg = 0.38g (Mars)

introduction – FD design – simulator – test flight – conclusions

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Specific forces

Specific forces in the Earth fixed reference frame due to the movement of the center of gravity of the aircraft:

Assume: ΩE = 0 and symmetrical along XB

Rewriting to body fixed reference frame:

Required accelerations (including gravity):

introduction – FD design – simulator – test flight – conclusions

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Flight director objectives

• Highly accurate partial gravity flight phase

• Partial gravity flight phase as long as possible

• Remaining within the safety limits of the aircraft

• Introducing enough stability margins

• Limited influence of varying pilot control behavior

Boeing 737 Primary Flight Display 5

Example of flight director

introduction – FD design – simulator – test flight – conclusions

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Design process of the flight director control law

1. Classical control theory using McRuer’s cross over model2. Adjusting and optimizing the flight director control law,

because:• Aircraft dynamics change during the maneuver (VTAS ≠

const.)• Partial gravity flight phase is short• Also time domain objectives• Measurement noise

introduction – FD design – simulator – test flight – conclusions

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Flight director control law

λg Knz Kq

0.00g

-0.15 -0.35

0.17g

-0.05 -0.25

0.38g

-0.15 -0.40

introduction – FD design – simulator – test flight – conclusions

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Dynamics of the controlled element

• Integrator dynamics near the cross over frequency

• Higher order dynamics for lower and higher frequencies

introduction – FD design – simulator – test flight – conclusions

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Influence of varying pilot control behavior

• Increased stability for higher pilot gain, except for lp1

• Constant partial gravity time

Simulation results:• 15.3 sec (λg = 0.00g)• 19.1 sec (λg = 0.17g)• 25.0 sec (λg = 0.38g)

introduction – FD design – simulator – test flight – conclusions

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Display design

introduction – FD design – simulator – test flight – conclusions

1. Air speed indicator2. Compass3. Vert. speed indicator4. Altitude5. Artificial horizon6. Spec. force indicator7. Spec. force error

indicator8. Flight direcotr bar9. Sequencer lights

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Experiment 1: flight simulator

• Method• Apparatus / aircraft model and flight conditions / subjects• Independent variables and dependent measures• Hypotheses

• Results• Duration of the partial gravity flight phase• Accuracy of the partial gravity flight phase• Workload / safety / flight experience of subjects• Wing leveler

introduction – FD design – simulator – test flight – conclusions

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Simona experiment

• Apparatus• Simona Research Simulator

• No motion

• Static control loading• Aircraft model

• Cessna Citation II• Incl. auto-throttle

• Flight condition• 3000m altitude• 125m/s VTAS

• Subjects• 4 Citation pilots• 5 students

introduction – FD design – simulator – test flight – conclusions

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Independent variables

• Partial gravity settings• λg = 0.00g (space)

• λg = 0.17g (Moon)

• λg = 0.38g (Mars)

• Display modes• Baseline , (6) & (7)

• Display 1 , (6), (7) & (8)

• Display 2, (6), (7), (8) & (9)

• Wing leveler • on and off Baseline displayDisplay 1Display 2

introduction – FD design – simulator – test flight – conclusions

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Dependent measures

• Duration• tλg (±0.050g)

• tλg (±0.075g)

• Accuracy• RMS ελg (±0.050g).

• RMS ελg (±0.075g)

• Safety• VTAS, max

• nz, max

• Workload• NASA TLX Workload rating

introduction – FD design – simulator – test flight – conclusions

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Hypotheses

1. The flight director will improve the maneuver accuracy and duration

2. The sequencer will improve duration and reduce workload

3. The wing leveler will reduce pilot workload and increase duration and accuracy

4. The results are not influenced by the flight experience of the subjects

introduction – FD design – simulator – test flight – conclusions

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Results of the Simona experiment - accuracy

• Accuracy is significantly better for λg = 0.17g • The flight director in combination with the sequencer

improves the accuracy significantly

introduction – FD design – simulator – test flight – conclusions

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Results of the Simona experiment - duration

• Shorter duration for λg = 0.38g than expected• Significant improvement for the flight director and

sequencer

introduction – FD design – simulator – test flight – conclusions

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Workload / safety / flight experience of subjects

• Workload • not influenced by the display• lower workload for λg = 0.17g

• Safety1. Display 2 2. Baseline3. Display 1

• Flight experience• No influence on duration • No influence on accuracy• No influence on safety

introduction – FD design – simulator – test flight – conclusions

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Results of the wing leveler experiment

• Improves duration• Improves accuracy• Reduces workload

introduction – FD design – simulator – test flight – conclusions

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Simulator experiment - summary

Hypotheses:

The flight director will improve the maneuver accuracy and duration

- The sequencer will improve duration and reduce workload

The wing leveler will reduce pilot workload and increase duration and accuracy

The results are not influenced by the flight experience of the subjects

introduction – FD design – simulator – test flight – conclusions

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Experiment 2: test flightmethod

• Cessna Citation II

• 30 parabolic flight maneuvers

• Four different pilots

• Display mounted in front of the pilots during flight

• Three partial gravity conditions

introduction – FD design – simulator – test flight – conclusions

• Two displays (Baseline & Display 2)

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Test flight

introduction – FD design – simulator – test flight – conclusions

28 | 3428 | 35introduction – FD design – simulator – test flight – conclusions

29 | 3429 | 35introduction – FD design – simulator – test flight – conclusions

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Test flight results

• Comparison to historical values:• Improved accuracy• Improved duration

• Due to limited number of flight no significant differences in the display modes

introduction – FD design – simulator – test flight – conclusions

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Comparison between simulator and real flight

• Zero gravity flight: better performance in real flight• λg = 0.17g better in simulator

introduction – FD design – simulator – test flight – conclusions

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Finishing the partial gravity flight phase

• The partial gravity flight phase is abandoned earlier in the real flight than in the simulator

• The partial gravity flight phase is abandoned earlier if λg = 0.38g (due to lack of dynamic pressure feedback to the control loading)

introduction – FD design – simulator – test flight – conclusions

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Conclusions

• The display including the flight director and sequencer improves the partial gravity maneuver in terms of accuracy and duration

• The flight director does not deteriorate safety and workload

• Performance for zero gravity is better in real flight than in the simulator

• The partial gravity maneuver is abandoned earlier in the Citation than in the Simona

introduction – FD design – simulator – test flight – conclusions

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Recommendations

• Use a different workload rating method

• Display design improvements:• Include audio signals• Combine the two specific force indicators• Visualize the safety margins

• Investigate the transition criteria given by Heuvel et al.

• Implement q-feedback on the control loading in Simona

• Investigate the early abandonment of the maneuver in the aircraft, and try to avoid it

introduction – FD design – simulator – test flight – conclusions

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Challenge the future

DelftUniversity ofTechnology

Flight director design for zero and partial gravity flightSimulation analysis and experimental results of the partial gravity maneuver

10-04-2023

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Borrel

Vrijdag 13 februari, 21:00Café ‘Het Pakhuis’Phoenixstraat 4C2611 AL Delft

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APPENDICES

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Aircraft transfer functions

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Off line simulation results

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NASA TLX Workload Rating

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Simona ANOVA’s

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Chance of correct flight

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Simona experiment - workload

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Simona experiment - safety

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Display recommendation

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Off-line simulation results

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