1

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Dr. Karl Bilimoria

NASA Ames Research Center

“Go for Lunar Landing” Conference

Tempe, AZ

4 – 5 March 2008

Lunar Lander Handling QualitiesLunar Lander Handling QualitiesTerminal Descent to TouchdownTerminal Descent to Touchdown

2

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

• Handling Qualities– Ease & precision with which the pilot can execute a flying task

– HQs depend on vehicle response, guidance cues, inceptors, etc.

– Comprehensive standards exist for aircraft

• NASA has initiated an effort to study handling qualities of piloted spacecraft designed for Constellation program

• Lunar Lander experiment– May 2007 at Ames, on the Vertical Motion Simulator (VMS)

– A first step in the handling qualities effort

BackgroundBackground

3

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Precision Landing Task: Horizontal ProfilesPrecision Landing Task: Horizontal Profiles

Two horizontal profiles– Centerline approach– 250 ft offset approach

Two horizontal profiles– Centerline approach– 250 ft offset approach

1,350 ft

Offset distance= 250 ft

LandingSite

Centerline ApproachLeft Offset Approach

Land within 15 ftof target center

4

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Precision Landing Task: Vertical ProfilePrecision Landing Task: Vertical Profile

0

100

200

300

400

500

600

700

800

-200 0 200 400 600 800 1000 1200 1400

Distance-to-go (ft)

INITIAL CONDITIONS:Distance = 1,350 ft

Altitude = 500 ftHorizontal speed = 60 fpsVertical speed = –16 fps

Pitch angle = 16 deg

INITIAL CONDITIONS:Distance = 1,350 ft

Altitude = 500 ftHorizontal speed = 60 fpsVertical speed = –16 fps

Pitch angle = 16 deg

Reference Trajectory95 sec to touchdown

Reference Trajectory95 sec to touchdown

Uncontrolled Trajectory31 sec to impact

Uncontrolled Trajectory31 sec to impact

Horiz spd = 0Vert spd = –3 fps

Dist = 0Alt = 150 ft

Trajectory based on Apollo missions:“Low Gate” to Touchdown

5

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Simulator Cab LayoutSimulator Cab Layout

Out the windowfield of view

6

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Cockpit DisplaysCockpit Displays

Guidance cues:– Roll, pitch, and yaw angles– Forward and lateral speeds– Altitude rate

Guidance cues:– Roll, pitch, and yaw angles– Forward and lateral speeds– Altitude rate

7

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

• Evaluate a basic model of Apollo Lunar Module

• Study handling qualities for various combinations of:– Control power (various levels of acceleration)

– Guidance (ON or OFF)

Lunar Lander Experiment ObjectivesLunar Lander Experiment Objectives

Control Power

Guidance

0.15X

0.2X

0.25X

0.3X

0.5X

1X(Baseline)

ONOffset Approach

OFFCenterline Approach

Pilots fly 3 approaches in each cell – Cooper-Harper Rating – Workload Rating (NASA-TLX) – Comments

Pilots fly 3 approaches in each cell – Cooper-Harper Rating – Workload Rating (NASA-TLX) – Comments

8

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

Control Power Study – Guidance OnControl Power Study – Guidance On

Handling Qualities RatingHandling Qualities Rating Task Load Index RatingTask Load Index Rating

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60 70 80 90 100

Control Power (% of nominal)

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Control Power (% of nominal)

Level 1: Satisfactory without improvement

Level 3: Improvement mandatory

Level 2: Deficiencies warrant improvement

Satisfactory for tasks that couldresult in crew or vehicle loss

Not satisfactory for tasks that couldresult in crew or vehicle loss

Evaluating a basic model of Apollo Lunar ModuleEvaluating a basic model of Apollo Lunar Module

9

Ames Research CenterAmes Research CenterKarl Bilimoria 5 March 2008 Lunar Lander Handling Qualities – Terminal Descent to Touchdown

• Control power study– Nominal configuration model is close to Level 1 boundary

– Handling qualities degrade rapidly after control power drops below 50% of nominal value

• Guidance is essential for precision landing task– Lateral offset approach not flyable without guidance

– Centerline approach very difficult to fly without guidance

• Suggested discussion topic:Does a ground-based simulator with high motion fidelity negate the need to build a LLRV-like vehicle for Cx?

Concluding RemarksConcluding Remarks