Light-Weight Deployable Radiator Structure

Status date

The new ESA Large Telecommunication In-Orbit Platform will require the introduction of advanced technologies in a number of areas, one of which is the need for large deployable radiators with high thermal performance and low mass. A potential way for substantial mass saving is the use of carbon fibre technology for the deployable radiator structure instead of classical aluminium construction.

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The main scope of the Light Weight Deployable Radiator (LWDR) pre-development activity is to prove the feasibility of a new generation of highly effective, light-weight, cost-effective deployable radiator panels. To meet this objective a downscaled CFRP radiator panel will be developed, designed, manufactured and tested in order to demonstrate that the design and the selected technologies are suitable for the future large platform deployable radiator.

Key issue is the mismatch of the coefficient of thermal expansion between the CFRP face sheets and the aluminium heat pipes, considering the specified temperature range of -65ºC to +75ºC.


Availability of a new generation of deployable radiators with higher thermal performance and lower mass than existing aluminium/honeycomb panels.


Specific design features of the light weight deployable radiator are:

  • Sandwich panel of approximately 5 m2 size with face sheets made from ultra stiff, high thermal conductivity carbon fibre reinforced plastics (CFRP) and aluminium honeycomb core,

  • Network of 4 embedded loop heat pipes with independent condensers in serial/parallel arrangement,

  • Optical solar reflectors (OSR) bonded on both radiator surfaces,

  • Interfaces for hinges, inserts and hold-down points (not part of the study).

The selection of the most promising layout of the condenser network was based on a careful trade-off, considering a broad range of criteria derived from design driving requirements such as thermal performance, compatibility with the mechanical and thermal environment, mass and recurring cost. Among the investigated design concepts a solution combining the advantages of a pure serial and a pure parallel layout proved to be the most attractive one:

Recommended design concept (combination of parallel and serial lines)

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This concept represents the best compromise in terms of pressure drop, internal volume, CTE mismatch, liquid/vapour separation and reliable sub-cooling and is recommended for further studies in Phase 2.

One of the fundamental problems to be solved during the LWDR development is the mismatch of the coefficient of thermal expansion (CTE) between the different materials: In the proposed design baseline the fibres in the radiator face sheets are oriented at +/-15º with respect to the LWDR longitudinal direction in order to be compliant with the eigenfrequency requirement. The CTE of the selected face sheet laminate is -3.31.10-6 1/K in longitudinal direction and +28.0.10-6 1/K in transverse directio


The LWDR predevelopment activity is divided in two phases:

  • Phase 1:

    • Task 1: AlphaBus LWDR Technology Specification

    • Task 2: Technology Review, Trade-off Criteria

    • Task 3: Trade-Off, Concept Selection, R&D Needs

  • Phase 2:

    • Task 4: AlphaBus LWDR Structure Specification

    • Task 5: Design of Flight Representative Radiator Panel

    • Task 6: Test Definition, Test Panel Design & Test Pred.

    • Task 7: Test Panel Manufacturing

    • Task 8: Test Execution & Results Evaluation

    • Task 9: Radiator Qualification Requirements
Current status

The contract was closed after the successful completion of the Phase 1 Review held in September 2005..