dva1 project status gary hovey and gordon lacy ngvla workshop, april 8-9 2015 nrc-herzberg astronomy...

DVA1 Project StatusGary Hovey and Gordon LacyngVLA Workshop, April 8-9 2015NRC-HerzbergAstronomy Technology Program - Penticton

DVA1 - Performance and Status

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: Design for Cost

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 For Performance

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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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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Superior Performance• Thermal• Wind• Gravity


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: 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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September 2014

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


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

• Primary reflector surface deviations. RMS error, uncorrected for aperture weighting 0.89mm, otherwise .7mm rms

• 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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Laser Tracker vs Holography of Primary

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Registration Panel

Laser Tracker Mount

RepairFeatures

SubmmMold

features


Reflector Temperature Stability

• Primary Reflector• Coupon Testing

5.62 μm/moC• DRAO test August 6th

5.42 ± 1.08 μm/moC

• Secondary Reflector (estimated) • 3.18 μm/moC < CTEsecondary < 5.62 μm/moC

• Aluminium > 4 times higher 23.6 μm/moC

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Surface Stability (no correlations with wind or temperature)

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0.0 5.0 10.0 15.0 20.0 25.0 30.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Temperature and Wind During Eighteen 1.5 Hour Holography Runs

Run Start: 1 Nov 2014 19:18:09 (PDT)Run End: 2 Nov 2014 23:22:47 (PDT)

Temp (°C)

Wind (mps)

Gust (mps)

Pk-Pk diff (mm)

RMS Difference

Elapsed Time in Hours

Tem

p i

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or

win

d i

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eter

s p

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eco

nd

, o

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RM

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iffe

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mm

Precision Observing

Standard Observing

Sunrise 2 Nov 14 @7:49 PDT ; Temp = -3C; ET = 11Hrs

ΔTemp/Δt = 5 °C/Hr


Average Surface Error of 18 Holography Maps (28 Hrs)

• RMS .85mm

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• Deviations from average .08mm RMS


MeerKat Receiver Noise Temperature Testing

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EMSS L-Band Receiver for MeerKat

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Azimuth Pattern at 1544.5 MHz (GOES West Satellite)

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Elevation Pattern at 1544.5 MHz (GOES West Satellite)

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Preliminary Tipping Curves Results

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8718.5

Results Preliminary and likely low by as much as 1.5K

58.5


Aperture Efficiency with MeerKat and New (LB) Horn

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Aeff/Tsys with MeerKat and New (LB) Horn

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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 Status27

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 ngvla workshop, april 8-9 2015 nrc-herzberg astronomy...

Documents

estimated performance

receiverdva1 performance

distortiondva1 performance

2014dva1 performance

durabilitydva1 performance

designdva1 performance

monocoque design

beam patternhigh performance