Using SeeYou for Soaring Flight Analysis

GPS-trace based flight analysis

Real Question: How I do become a better cross-country glider pilot

Agenda

• Overview SeeYou capabilities

• Quick review of theoretical underpinnings of X-country flight optimization

• Example of competitive analysis of G-Cup flights on May 19th, 2003

Overview SeeYou Capabilities

• Turnpoint Database Management– Importing/creating new turnpoints– Modifying/deleting turnpoints

• Task Database Management– Importing tasks/creating new tasks– Modifying/deleting tasks

• GPS Trace Analysis– Importing GPS traces (connection wizzard)– Analyzing flights

• 2-D flight analysis– Single flight– Multiple flights– Synchronization– Customizing screen

• 3-D flight analysis– Single flight– Multiple flight– How to move about

• Barograph-type analysis of flight parameters– Cross-matching of parameters

• Statistical Analysis– Info Available– Selections

• Quick review of theoretical underpinnings of X-country flight optimization– MacCready (deterministic)– Mathar (stochastic)– Cochrane (stochastic)

MacCready Theory• Q: How fast should I fly based on known lift conditions ahead of me in order to minimize

time from A to B when my altitude is unlimited?• Answer: Classic speed-to-fly (MacCready) theory – provides explicit interthermal cruise

speed and implicit rule, in which thermals to climb

A BDistance s

Net lift l

lv

vpss

v

st

target

sink/liftairmass alintertherm/)(

targetB to A

target

vcruise

polarsink

vtarget

polarsink ps at

vtarget

Net lift l in next thermal +/-inthermal

airmass sink/lift

Cruise time to next thermal

Time spent regaining altitude in thermal

Two key constraints of MacCready theory:• Deterministic model, based on known net lift l – which in reality is unknown• Doesn’t account for limited altitude

Constraint 1: Uncertain lift – R. Mathar, Technical Soaring Oct 1996

• Q: How fast should I fly based on unknown lift conditions ahead of me in order to minimize time from A to B?

• Answer: If there is a distribution of expected lift set the MacCready ring (or equivalent device) to the harmonic mean rather than the arithmetic mean (=straight average)

Mathematics:

Practice:

l

1E

v

vpss

v

s

lv

vpss

v

sEE[t

target

sink/liftairmass alintertherm/)(

target

target

sink/liftairmass alintertherm/)(

targetB to A

target

target]

Key insight• Provides theoretical underpinning for common sense strategy to fly a little

more on the cautious side based on uncertainty

Lift distributionLift

(knots) ProbabilityMacCready

SettingCruise Speed

(LS-8 dry)

Cruise Time for 10 nm

(min)

Time to climb (min)

Total Time

Outcome A: 1 1/3 4 76 7.9 16.5 24.3Outcome B: 4 1/3 4 76 7.9 4.1 12.0Outcome C: 7 1/3 4 76 7.9 2.4 10.2

Average 15.5

Outcome A: 1 1/3 2.15 69 8.6 14.1 22.7Outcome B: 4 1/3 2.15 69 8.6 3.5 12.2Outcome C: 7 1/3 2.15 69 8.6 2.0 10.7

Average 15.2

Calculation of average speed flying according to MacCready theory using the arithmetic mean

Calculation of average speed flying according to MacCready theory using the harmonic mean

Constraint 2: Limited Altitude – R. Mathar, 1996

• Q: What is the best strategy in order to minimize time from A to B given variable known lift conditions and limited altitude?

• Answer: Depends on glider performance and the altitude available. With limited glider performance and/or limited altitude the weakest lift needed to get around the task is dominant in determining optimum speed-to-fly

Example:

Key insight• Provides theoretical underpinning for common sense strategy to fly a little

more on the cautious side with limited altitude

A B

Ground

2 knots 6 knots 2 knots

Combining the Constraints – J. Cochrane, 1999

• Q: What is the best strategy in order to minimize time from A to B given uncertain lift conditions and limited altitude?

• Answer: No closed form solution. Numerical investigation yields insights:Confirmation of standard McCready theory:• Set McCready ring (Speed-to-fly computer)• Fly best speed when lift below setting• Circle, if above settingAdditional insights relative to McCready theory:• Lower the setting as you get lower• Increase setting with altitude• Use setting well below best climb of day• Start final glides low & aggressive, end conservativeDeficiencies:• Thermals assumed static (daytime & height variability)• Information driven discrete strategies (clouds, topography) • Competitive dynamics (game theory, scoring asymmetries)• Wind, ballast options etc.

Key insight:Common sense is confirmed; implementation requires a statistical mindset when flying; real life too complicated for theory

• Example of competitive analysis of G-Cup flights on May 19th, 2003

A beautiful day…the weather on May 19th, 2002 9 completions to analyze1K2, B21 (2 flights), DRT, FD2, PX, SM, TB, TUP

Lift as a function of local time

-

1

2

3

4

5

6

7

8

9

10:00:00 11:00:00 12:00:00 13:00:00 14:00:00 15:00:00 16:00:00 17:00:00

Daytime (local)

Ave

rag

e L

ift

Rec

ord

ed (

kts)

Early bird, doesn’t catch the worm……but potentially gets to complete the G-Cup twice in a day!

Dependence of Speed achieved on Start Time

40

45

50

55

60

65

70

10:00 11:00 12:00 13:00 14:00 15:00 16:00

Task Start Time (local)

Avg

Sp

eed

(m

ph

)

The Pros leave at ~1:30 pm…

…with a few newcomers

painting thermals on coursefor them

Rush, ΔΣ (=Delta Echo)!

Dependence of Speed Achieved on Interthermal Cruise

40

50

60

70

55 60 65 70 75 80 85

Average Interthermal Cruise Speed (local)

Tas

k S

pe

ed

(m

ph

)

High Interthermal speed is not sufficient

for success…

…but beginners might take heart and lower

that nose…

Dependence of Speed Achieved on Interthermal Cruise Speed Variability

45

50

55

60

65

70

0 5 10 15 20

Interthermal Speed Variability (mph)

Ach

ieve

d T

ask

Sp

eed

(m

ph

)MacCready alright…

Too much of a good thing…is a

bad thing…

…especially when easy does it!

Dependence of L/D Achieved on Interthermal Cruise Speed Variability

30

35

40

45

50

0 5 10 15 20

Interthermal Speed Variability (mph)

Ach

ieve

d L

/D...but in modesty lies wisdom indeed!

Time well spent…?Composition of Task Time

0:00

1:00

2:00

3:00

4:00

0

10

20

30

40

50

60

70

80Time Circled (min)

Time in Straight & Level

Avg Spd (mph)

Circling for lift is so 20th century…

Scaling new heights

Composition and Amount of Altitude Gains Needed

-

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

13,000

Alt

itu

de

(m)

0

10

20

30

40

50

60

70

80

Task

Sp

eed

(m

ph

)

Height gain in straight f light (m)Height gain circling (m)Avg Spd (mph)

Low energy consumption is the name of

the game, even when

energy is free

Summary of Relevant statistics

Comp ID GliderAvg Spd

(mph)Start Time

LocalRelative Detours

Height Gain Circled (m)

Avg Climb (knots)

B21 -2 ASW 24 68.4 13:29 1.02 3,630 5.2

TB ASW 28 66.1 13:24 1.03 4,620 5.1

PX - normalized Scimitar 64.4 13:09 1.06 5,291 5.2

TUP LS-3 60.9 15:10 1.06 6,076 4.8

DRT LS-3 52.1 12:25 1.08 6,290 3.9

B21 ASW 24 51.5 10:37 1.09 5,620 3.8

1K2 LS-3 50.5 12:58 1.04 6,043 2.9

SM - normalized Kestrel 49.3 13:09 1.06 7,050 3.1

FD2 LS-3 46.7 13:18 1.06 5,519 3.1

40

45

50

55

60

65

70

10:00 11:00 12:00 13:00 14:00 15:00 16:00

Summary of Relevant statistics 2

Comp ID

Time Circling

(min)

Time in Straight &

LevelTotal Time

Height gain in straight flight

(m) Avg L/D

Avg Cruise Speed (knots)

StdDev Speed

Average Height

B21 -2 0:22 1:45 2:08 4,450 48 74 10 1,201

TB 0:29 1:43 2:12 3,521 40 76 11 1,317

PX - normalized 0:32 1:43 2:16 5,510 38 79 13 1,437

TUP 0:41 1:42 2:23 3,996 34 79 16 1,535

DRT 0:52 1:56 2:48 3,552 36 71 10 1,473

B21 0:48 2:02 2:50 4,260 47 68 7 1,127

1K2 1:07 1:45 2:53 3,118 35 75 7 1,264

SM - normalized 1:14 1:43 2:57 4,578 35 76 13 1,326

FD2 0:57 2:10 3:07 3,202 39 59 3 1,226

40

45

50

55

60

65

70

10:00 11:00 12:00 13:00 14:00 15:00 16:00

Av

g S

pe

ed

(m

ph

)