DVA1 Project Status Gary Hovey and Gordon Lacy SKA Visit, Sept 9 2014 NRC-Herzberg Astronomy...

DVA1 Project StatusGary Hovey and Gordon LacySKA Visit, Sept 9 2014NRC-HerzbergAstronomy Technology Program - Penticton

DVA1 - Performance and Status

Rough Agenda

• 09:00 Tour DVA1 (muster in DRAO foyer) • 10:00 Tour Labs (AFAD, LNA, ADC, EVLA, Kermode)• 10:45 Coffee• 11:00 DVA1 update (Gordon and Gary)• 11:45 SKA Structure update (Dean and Gordon)• 12:30 Lunch OK Falls• 13:30 Tour DVA1 fabrication facility OK Falls• 15:00 Coffee & wrap-up discussions at DRAO• 16:00 Free• 17:00 Depart DRAO• 19:00 Dinner at Hooded Merganser

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Outline

• DVA1 Overview: Motivation, goals and objectives• Key innovations• Optics results• Mechanical and fabrication results• Testing and future plans

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SKA Dish Design Considerations (www.skatelescope.org)

• Imaging dynamic range – The signal range in terms of intensity over which the SKA will be able to observe. It also means that the dishes have to have extremely stable pointing and accuracy in harsh desert environments.

• Design for mass manufacture – Making the most efficient and technically outstanding design choices, whilst keeping to a budget that comes within that set out by the SKA Organisation

• Low operating Cost per dish – Once built, how to maintain them and operate the telescopes on the most cost effective budget. The reliability of the dishes will be a critical factor here.

• Maximum sensitivity per dish - Ensuring each dish delivers the maximum sensitivity and that this is consistent between all of the dishes in the array

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DVA-1: Design Approach and Goals

SKA Challenge: A leap in sensitivity and dynamic range requires a corresponding leap in antenna cost/performance.

Goals and Objectives: Investigate, develop and demonstrate innovations that improve antenna cost/performance.

Lower cost through− Simplicity of design− Minimal part count− Modular design− Low labour content− Minimal use of custom sizes and part− Use of advanced materials− Use of scalable mass fabrication processes− Optimal optics over the prime frequency range 1-10GHz.− Feed-up design

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DVA1: Design Approach and Goals (cont.)

Improved optics and stability performance through• Use of advanced materials

• Shaped optics to maximise Aeff / Tsys

• Improved stability over all load conditions− Feed-high design lowering peak cross section to wind− Compact turning-head and mount to minimise moments− Single piece rim supported reflector

• immunity to translational loads• distortions uniform and low order

− High stiffness and low CTE using carbon fibre composites− Composite reflector with embedded metal mesh

• Reflectivity of Aluminium with the stiffness of carbon.• Low moving mass -> superior closed loop response

• Design for low maintenance upkeep and burden, as well as long life and durability

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Existing Designs

Australian SKA Pathfinder

Allen Telescope Array

South AfricanMeerKat

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Evolution of Improved Cost/Performance

Improving Materials, Design, and Manufacturing

Cost/performance

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Background

• Began investigating composites in 2005• Built two reflectors in 2007• Started collaboration with US-TDP in 2009

− Design phase lead by US-TDP− Construction phase lead by NRC

• CoDR in early 2011• PDR in late 2011• CDR in mid 2012• Fabrication reflector and pedestal mid-2013• Final assembly and test through to fall 2014

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DVA-1: Designed for High Dynamic Range Capability

• High Thermal Performance• Rim supported monocoque design along with very low CTE materials keeps all

thermal movement both small and very uniform to minimize effect on beam pattern

• High Performance in Wind and Gravity• Central compliant connector allows some structural sag without inducing unwanted

distortion at center of dish

• Rim supported design keeps dish deflections to absolute minimum and concentrates any deflections at rim where effect on performance is small.

• Extremely deep truss back structure keeps dish shape as close to rigid as is possible.

• High Overall Optics Stability• Secondary and feed platform support optimized to maximize stiffness using shape

optimization software.

• Secondary and feed support tubes use zero and matched CTE carbon tubes for extremely high thermal stability.

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DVA1: Design Features

The main design elements are:

15m Gregorian offset feed-high optics

• Unblocked aperture

• Large space for feeds

• Stiffer, lower cost than feed-low

• Molded single piece rim-supported composite reflectors

• Tubular backup structure

• Tubular composite feedlegs

• Pedestal-type mount allows small offset to elevation axis

• Deep truss backup structure with central pocket for pedestal mount

• Central compliant connector allows movement in wind without distortion

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DVA1: Estimated Sensitivity

DVA-1 Aeff/Tsys using Corrugated HornsAssumes 15K Receiver

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DVA1: Estimated Performance in Wind

Beam Pattern at 10 GHz.25 kph Wind at 15 degree Elevation (Blue)Undistorted (Red)

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DVA1 Predicted Temperature Stability

Beam Pattern at 10 GHz.25 Celsius Thermal Change (Blue)Undistorted (Red)

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Beam Pattern at 18GHz 15 Elevation

Undistorted (Red). 15 degree Elevation (Blue)Effect mainly a pointing correction as 25kph wind has a negligible effect on pattern

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DVA1 Primary Reflector Damage and Repairs

Collapsed Surface After being popped out with air bags

DVA1 Repair Activities

DVA-1 Reflector Repairs

DVA-1 Reflector Accuracy After Repairs

• Post repairerror = 1.0mm rms

• Excluding repaired areas error = 0.7mm rms

Notes:1. Errors are from ideal and

include mold errors.

2. No aperture weighting used, otherwise rms error would be less.

DVA-1 Secondary Reflector Accuracy

•Un-weighted by illumination: Surface error = 0.2mm rms

•Weighted by illumination Surface error = 0.11mm rms

Improved Results: GDSatcom Secondary Reflector

•We have now built two sub reflectors for the GDSatcom Meerkat project

•RMS of reflector 0.090mm

•Mold RMS 0.058mm


DVA-1: Composite Performance

Structural Test Composite Design Consideration

Metallic Design Consideration

Creep high static load high static load

Static Strength Material properties Material properties

Fatigue Life High cyclic load High cyclic load

Glass Transition Temp. Choose resin with sufficiently high value.

NA

Impact Resistance Engineering requirement Engineering requirement

Galvanic Corrosion Encapsulate reflective layer Paint and primer

UV, Moisture, Humidity Paint (no primer required) and resin properties

Paint and Primer

Reflectivity Degradation Paint (no primer required) Paint and Primer

Fungus growth Paint Paint

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Surface Resistance Measurements

TE011 Mode Resonant Frequency 8.4 GHz 14.6 GHz 18.4 GHzTest Sample Surface resistance (Ohms/square)Aluminium 6061-T6 0.0415 0.0562 0.0739Copper 0.0244 0.0306 0.0469DVA1 Reflector Test Panel 0.1274 0.2431 0.3093Improved Layup Test Panel 0.0692 0.0955 0.116

TE011 Mode Resonant Frequency 8.4 GHz 14.6 GHz 18.4 GHzTest Sample Equivalent Noise Temperature in KAluminium 6061-T6 0.131 0.177 0.233Copper 0.077 0.096 0.148Secondary Reflector Test Panel 0.401 0.766 0.975Improved Layup Test Panel 0.218 0.301 0.367

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Pointing: Preliminary Tilt Measurements

0 1 2 3 4 5 6 7 8 9 10 11 12 13 140.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0 DVA-1 Mount Load Test, Tilt vs Force Y, 2014-05-08

Tilt 1 Y E-W TurnheadTilt 2 Y E-W Support

Force Y direction ( kN )

De

fle

cti

on

(

arc

-se

c )

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Coefficient of Thermal Expansion (CTE) Tests

• CTE values are notoriously difficult to measure in composite materials

• Lab CTE values were compared with field measurements taken on the primary reflector

• Results compare very well

Data Source CTE value (μm/moC)

Toray Coupon Testing 5.62 (no error values given)

DRAO test August 6th 2014 5.42 ±1.08

6061 Aluminum (for comparison) 23.6

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Primary Dish Deflection as a Function of Elevation Angle

• Primary reflector positional data tracked with a laser tracker for 19 points over elevation angles ranging from 20 degrees up to 85 degrees.

• Experiment was conducted at night to minimize temperature variations• Data has not yet been interpolated to the full dish surface• Initial results in tabular form look consistent with CAD model predictions.

Deviations within a few millimeters.

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Primary Dish Deflection Target Layout

-10000 -8000 -6000 -4000 -2000 0 2000 4000 6000 8000 10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

Pt 1

Pt 2

Pt 3

Pt 4

Pt 5Pt 6

Pt 7

Pt 8Pt 9

Pt 10

Pt 11

Pt 12

Pt 13

Pt 14

Pt 15

Pt 16

Pt 17

Pt 18

Pt 19

Dish Target Layout

"Y1"

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Primary Dish Deflection Tabular Data, Delta Z values

Point # 20.00 30.00 40.00 50.00 60.00 70.00 80.001 -1.66 -1.28 -0.69 -0.39 0.30 1.00 1.492 -0.82 -0.64 -0.38 -0.26 0.14 0.46 0.583 -1.52 -1.09 -0.57 -0.27 0.17 0.57 0.794 -0.83 -0.66 -0.43 -0.24 0.16 0.56 0.925 0.09 -0.02 -0.12 -0.15 0.11 0.38 0.666 0.65 0.44 0.23 0.08 -0.11 -0.37 -0.497 -0.58 -0.46 -0.28 -0.11 0.11 0.34 0.588 0.39 0.20 0.05 -0.07 -0.04 -0.06 -0.169 0.86 0.58 0.31 0.10 -0.08 -0.23 -0.46

10 0.39 0.23 0.12 0.06 -0.03 -0.07 -0.0711 0.52 0.33 0.20 0.11 -0.07 -0.15 -0.1312 1.05 0.80 0.54 0.22 -0.23 -0.63 -0.9413 1.28 0.93 0.63 0.38 -0.17 -0.37 -0.3714 1.32 0.94 0.69 0.48 -0.16 -0.37 -0.3315 1.25 0.88 0.61 0.38 -0.13 -0.39 -0.3916 1.52 1.05 0.69 0.42 -0.09 -0.35 -0.4117 1.32 0.89 0.56 0.24 -0.09 -0.40 -0.5818 1.42 1.02 0.75 0.44 -0.09 -0.33 -0.4119 1.17 0.90 0.72 0.45 -0.15 -0.33 -0.39

Delta Z errors in mm for 19 tracked points as a function of elevation angle.

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Primary Dish Surface Scan, Rim Horizontal (Bird Bath).

• Primary reflector surface deviations. RMS error, uncorrected for aperture weighting 0.89mm

• Most of surface is within ±1.0mm (green)

• Most red areas are repaired areas, a result of the helicopter incident

• Almost all other features are in the mold surface (horizontal banding, grid feature in upper right quadrant).

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First Light Spectra

Sun @ 11.75 to 13.25 GHz Nimiq 6 Ku band Satellite12.2 to 12.7 GHz

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First Beam Scan Results (Preliminary)

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

Azimuth Beam Scan

Scan time in seconds

Gai

n i

n d

B r

elat

ive

to m

iniu

m v

alu

e

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

Elevation Beam Scan

Scan time in secondsG

ain

in

dB

rel

ativ

e to

min

imu

m v

alu

e

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RF Testing

Ku band holography• Aperture/surface errors• Antenna pattern

Pointing behaviour• Stability• Repeatability• Performance over load cases,

gravity, wind and temperature

Sensitivity• Tipping curves• Aperture efficiency

Ku Band Horn

MeerKat L-band receiver

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Cost

Item Materials Labour Sub-contract Totals

Reflectors, feed platform and support structuresComposite Dish Surface, Secondary, Central

Reinforcement $111,000 $63,400Composite Backing Pieces, fabrication portion, not

including molds $23,250Dish Rim Connector, labour (material in line 3) $14,000Ball studs $6,132PDSS $84,874Feed Platform $6,700Secondary Support Structure $85,000

Sub Totals $111,000 $77,400 $205,956 $394,356Pedestal Components

Tower, contract with Minex Engineering $300,000Tower, misc extra parts, package 1 $19,920Tower, misc extra parts, package 2 $90,600Tower, additional items $14,836Drive system (motors, control system and encoders) $43,000Painting $5,000

Sub Totals $473,356 $473,356

Grand Total $867,712

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Issues and Technical Risks

• Key retired technical (technology) risksComposite reflectors meet requirements for

− Reflectivity− Mechanical and thermal properties− Surface accuracy

• Outstanding risks now very low. − Majority have been mitigated by simulation/measurement− Those remaining will be retired by RF testing

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DVA1 - Performance and Status35

Questions?

Gary Hovey, Project Manager

[email protected]

Gordon Lacy, Project Engineer

[email protected]

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DVA1 Project Status Gary Hovey and Gordon Lacy SKA Visit, Sept 9 2014 NRC-Herzberg Astronomy...

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