Voice of the Engineer
R15901: AIRBORNE WIND ENERGY BASE STATION
Background
•Airborne wind energy planes are designed to simulate the tip
of the conventional wind turbine blade
•Operate at higher altitudes than conventional wind turbines
•Multiple methods to harness the energy
• Tether reel system
• Turbines on-board the plane conducted through tether
Figure 1: Diagram showing swept areas of a conventional
horizontal axis wind turbine(HAWT) and an tethered airfoil
system.
Problem Statement
Goals:
◦
◦
◦
◦
Design a Base Station that allows for continuous horizontal circular tethered unpowered flight
Implement a reel system to change the tether length during flight
Allow for rotation of the base station as the plane moves around the circle
Implement a bridle system to connect to the plane
Stakeholders
◦
◦
◦
◦
Dr. Gomes
Professor Hanzlik
P15462
MSD Office
Functional Decomposition
Allow for continuous
horizontal circular
tethered unpowered flight
Maintain Connection
with ground
Maintain tether tautness
Connect tether
to Base Station
Change tether
length
Allow for
manual
control of reel
system
Keep plane in horizontal
circular flight path
Allow for full 360 degree
tether rotation
Allow tether
tension to rotate
connection point
Rotate freely
without slip
Connect tether to plane
Evenly distribute
tether tension
load
Maintain
constant bank
angle during
flight
Engineering Requirements
rqmt. #
Source
Function
S1
S2
S3
FD
FD
FD
Allow plane force to rotate connection point
Maintain constant bank angle during flight
Keep plane in horizontal flight path
S4
S5
FD
FD
S6
CR
S7
S8
CR
FD
Change tether length
Allow for manual control of reel system
Achieve continuous horizontal circular flight
path
Achieve continuous horizontal circular flight
path
Evenly distribute tether tension load
S9
S10
CR
FD
S11
S12
S13
CR
FD
FD
S14
S15
S16
S17
S18
CR
CR
CR
FD
FD
Record videos of all flights
Rotates freely without slip
Achieve continuous horizontal circular flight
path
Change tether length
Change tether length
Achieve continuous horizontal circular flight
path
Reel system to change tether length
Base Station with Tether Connection
Maintain tether tautness
Evenly distribute tether tension load
Unit of
Measure
Marginal
Value
Ideal Value
lb
degrees
mph
5
15
10
1
30
5
Minimum torque required to rotate reel system
ft/s
lb-in
3
50
5
25
Flight path diameter
ft
60
30
Maximum glider speed
Maximum tether tension
ft/s
lb
80
250
Most flights
recorded
0.05
100
500
All flights
recorded
0.002
Engr. Requirement (metric)
Minimum tether tension required to rotate base
station
Minimum bank angle required for sustained flight
Minimum wind speed for unpowered flight
Reel system maximum feed rate
Recorded videos of all flights
Bearing friction coefficient for rotation
Binary
N/A
Duty Cycle of Propeller
Time to make tether taut
Tether length
%
sec
ft
50
5
0
1
Number of pilot inputs required to maintain flight path
Power required for reel system
Weight
Percentage of flight with taut tether
Tension Load per connection point to plane
Count
W
lb
%
lb
15
5
20
75
200
5
2
10
95
50
Customer Requirements
1 Base Station with Tether Connection
2 Allow for full rotation of the tether
3 Achieve continuous horizontal circular flight path
4 Reel system to change tether length
5 Bridle system to attach to plane and maintain constant bank angle
6 Use a provided bought plane or P15462's plane
7 Record videos of all flights
5
5
5
5
3
1
1
3
5
5
5
5
1
5
1
3
5
3
5
3
5
5
1
1
5
1
1
1
5
5
3
5
5
5
1
5
5
5
1
5
5
5
1
5
Tension Load per connection point to plane
Weight
3
Percentage of flight with taut tether
Power required for reel system
Number of pilot inputs required to maintain flight path
Tether length
Time to make tether taut
Duty Cycle of Propeller
Bearing friction coefficient for rotation
Recorded videos of all flights
Maximum tether tension
Maximum glider speed
Flight path diameter
Minimum torque required to rotate reel system
5
Reel system maximum feed rate
Minimum wind speed for unpowered flight
Minimum bank angle required for sustained flight
Minimum tether tension required to rotate base station
Customer Weights
House of Quality
Engineering Metrics
Cus
5
5
5
5
Concept Generation
Brainstormed Components
Concept A
Concept B
Concept C
Concept D (Current Method)
Concept E
Take-Off Method
Start Taut
Start slack and hand launch
Start taut
Start slack and hand launch
Start taut
Reaching Altitude
Lasso
Lasso
Fly Straight up
Fly Straight up
Lasso
Reel by hand manually
DC Motor powering gear
system with maunal switch
Reel System Method
Switch to turn on/off and
Automated DC Motor with gear Automated DC Motor directly
reverse direction DC Motor
system
connected to shaft
directly connected to shaft
Reel System Connection
Mounted to base station with
metal plate
Mounted at shaft ends
Glued in
Held by team member
Mounted at shaft ends
Plane Tether Connection
2-point bridle
3-point bridle
Ball and Socket Joint
Snuggie
Snuggie
Tether Rotation
Implementation
Allow reel system to rotate
Shaft attached to bearings
Allow reel system to rotate
Rotates without tracking
Use circular plate with hole
for tether mounted above
reel system
Base Station Ground
Connection
Metal stake in ground
Anchor weight
Use clamp that goes into
ground
Metal stake in ground
Metal stake in ground
Materials
Combination of the three
Steel
Aluminum
Combination of the three
Combination of the three
Pugh Charts
Selection Criteria
Cost
Weight
Time to Complete
Capability of Reel System
Amount of Control Required
by Pilot
Manufacturability
Ease of Tether Rotation
Ability to Maintain Flight
Path
Sum +'s
Sum s's
Sum -'s
Concept A as Datum
Concept A
Concept B Concept C Concept D Concept E
(Datum)
+
+
+
+
+
+
s
+
+
+
s
-
+
-
-
-
+
-
+
s
+
-
+
+
s
-
-
-
2
3
3
4
1
3
4
0
4
5
0
3
Concept E as Datum
Selection Criteria
Concept A Concept B Concept C Concept D
Cost
Weight
Time to Complete
Capability of Reel System
Amount of Control Required
by Pilot
Manufacturability
Ease of Tether Rotation
Ability to Maintain Flight
Path
+
+
+
+
+
s
+
+
+
-
+
+
-
-
-
+
-
-
+
+
s
-
Sum +'s
Sum s's
Sum -'s
3
0
5
5
0
3
2
2
4
3
0
5
Concept E
(Datum)
Risks  Feasibility Analyses
Flight path not feasible
◦ Perform analysis to prove that this flight path will allow for gliding flight
Tether Tension too high for plane to maintain flight path
◦ Perform calculations to ensure that tension never exceeds a specified limit
◦ Develop a take-off method to avoid initial jerk of the tether going taut
Plane is too difficult to control
◦ Design bridle that will take away certain degrees of freedom to require less input from the pilot
Wind Gusts too high for reel system to maintain tether tautness
◦ Perform calculations to find the feed rate required of the reel system to maintain tether tautness
Next Steps
Uncertainty and Questions:
◦ Ideas for allowing rotation of the base station as the tether rotates in horizontal circle
◦ Is it feasible to develop an automated control system for regulating tether length?
◦ Should there be multiple projects running concurrently to develop the control system and base station?
Moving Forward:
◦ Meet with Professor Hanzlik and Dr. Gomes to discuss current progress
◦ Perform feasibility analyses
◦ Decide on resources for the project and number of projects
Questions?