CLAV for the USV

In the frame of a contract with CIRA (Centro Italiano Ricerche Aerospaziali) TSD enterely designed, developed and manufactured the Carrier Located Avionics (CLAV) for the Unmanned Space Vehicle (USV) that has flown on february 2007.

The configuration of the CLAV was based (from the electronic point of-view) on the following main blocks:

Data Conversion Unit (DCU)
N.1 Batteries dedicated to the DCU (DCUBATT1)
Remote Power Management System (RePMS)
N.6 Batteries dedicated to the RePMS
Cooling Fans & Actuator for the heat exchange louvre

The CLAV design and manufacturing followed rigoruous criteria both from the electronic and thermo-structural point of view.


The main tasks of the Remote Power Management System are hereinafter listed:

To transfer electrical power to the vehicle Electrical Power System for all the time the USV is connected to the carrier
to allow the battery charging of the CLAV;
HK data collection of the CLAV;
HK data transmission towards the USV via RS422;
To power  the FANs and the Actuator of the heat exchange louvre.
To acquire the temperature of the CLAV Bay environment

The RePMS consists of a multimoduel platform based on the following components:

1 x Remote Power Control Unit (RePCU)
1 x Remote Power Distribution Module (RePDM)
6 x Remote Battery Interface Modules (ReBIMs)
2 x Remote Power Conditioning & Distribution Modules  (RePCDMs)
1 x Remote Back-plane (RePBP)

The main specification of the unit are:

Data exchange between all the RePMS electronic boards performed by means of RS485 serial bus;
RS422 I/F to decode commands coming from the USV;
2 x internal independent power bus providing, +28V, +5[VDC] power lines, to supply all the RePMS electronic modules;
1 x reundant input for external power source @ 28V (by batteries or by EGCE external power supplies);
6 x  Power I/Fs towards the CLAV batteries;
2 x redundant power outputs to supply the FANs and the actuators for the louvre;
2 x power bus outputs towards the other CLAV Units;
SMBus I/F for battery status monitoring;
Power Consumption: 40[W] @ 28[VDC]
Total output power: 2kW  @ 33V
Dimensions: 620x390x410 [mm x mm x mm];
Weight: 41.5 [Kg]

All the boards present in the RePMS are functionally similar to those described for the PMS unit.

CLAV Container and its thermal control system
The main goals reached in the CLAV container realization were:

•   Optimization of the mass and volumes of the electronic units into the bay;
•  Optimization of the positions of the electronic units into the bay in order to minimize the length and weight of the harness;
•   Mechanical robustness of the structures and careful mechanical design in order to accommodate the subsystems used for the thermal control (heat-pipes, heat exchange and related motorized louver, FANs, etc.) and to obtain the desired thermal flows

The implemented thermal control system were comprised of heat pipes. The heat-pipes conduct part of the heat, produced by the RePMS, toward the Batteries (equivalent thermal conductance of 7.5 W/°C) and toward the heat-exchanger located outside the CLAV bay (equivalent thermal conductance of 30 W/°C). The Heat-exchanger has a louvre with its own Actuator: it is aimed at transferring to the environment a proper amount of the heat dissipated, inside the CLAV, by the electronic equipment. Two FANs (operating in Fast/Slow mode) are used to increase the CLAV heat-exchanger performances, on ground and during the flight, at altitudes, which permit them to work properly.

A MLI Blanket is used with the purpose of avoiding an excessive cooling of the CLAV Bay when it’s at high altitude. MLI Blanket was based on Multilayer insulator and thermoinsulating wool.

The CLAV characteristics are:
•    Dimensions: 533x1945x830 [mm x mm x mm] (including the carter for the FANs)
•    Weight: 53.1 [kg]