AEROSPACE
EUROHAPS
The pressurisation system for a
stratospheric platform demonstrator
PROGRAMME
European Defence Fund (EDF)
CONSORTIUM
Thales Alenia Space, coordinator
21 partners and 18 subcontractors from 11 countries
OUR ROLE
Pressurisation system: design, simulation and experimental de-risking
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OBJECTIVE
A HAPS — High-Altitude Platform System — is an aircraft that behaves like a satellite. It flies above 18 km, in the stratosphere and above ordinary air traffic, holding station on the winds at that altitude and running on solar energy, which is what lets it stay up long enough to provide a service rather than a pass.
EuroHAPS was selected by the European Commission in 2022 and is funded through the European Defence Fund, backed by six defence ministries: France, Italy, Spain, Germany, Hungary and the Czech Republic. Thales Alenia Space coordinates a consortium of 21 partners and 18 subcontractors from 11 countries, among them CIRA, Elettronica and Leonardo in Italy, ONERA and CEA in France, INTA in Spain, and ESG and TAO in Germany.
Three demonstrators are being built: a scaled Stratobus, a high-altitude hybrid airship, and autonomous stratospheric balloon systems. What they are for runs from LIDAR observation and COMINT/ELINT missions to broadband telecommunications, Earth monitoring and maritime surveillance.
NablaWave’s part is the pressurisation system: the machinery that keeps the envelope at pressure through a flight where the air outside is thin, cold and changing.
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OUR CONTRIBUTION
Design and fluid-dynamic and structural simulation of both subsystems, then the instrumentation that measures them, then the testing that proves it.
Low pressure subsystem. The low pressure compressor; the delivery valve to the aircraft; the bleed valve that starts the compressor and carries its control strategy; the low pressure relief valve; an ultra-lightweight thermally insulated electronics box; a pitot flow meter with distributed sensing; and the piping that integrates the sensors.
High pressure subsystem. A high pressure compressor with an integrated heat exchanger, which is what holds the motor inside its temperature limit; ball valves driven by off-the-shelf actuators; the bleed valve and its control strategy; the high pressure relief valve; and a venturi flow meter integrated into the delivery ducts rather than added to them — on a stratospheric platform every gram is argued over.
The sensor board. One board serving both subsystems: up to seven differential pressure sensors whose range is adjustable in software, so accuracy holds as the altitude changes; one absolute pressure sensor; up to four PT1000 or thermocouple temperature channels; and integrated heating resistors so the board works down to −60°C while keeping each sensor inside its own compensation range. It was tested at −60°C in our own facility.
Testing ran in the climatic chamber and on the test bench — design and verification in the same hands, which is the only way the second one feeds the first quickly enough to matter.
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OUTCOMES
The campaign was experimental de-risking: find out what breaks on the ground, cheaply, rather than at 20 km.
Sensor board. Accuracy checked at ambient temperature and cold against reference sensors; power-up and temperature-hold tested at 60°C; then the climatic chamber at −60°C and 7500 Pa, which is the stratosphere as closely as a laboratory reproduces it.
Inverter and electric motor for the high and low pressure machines: endurance at maximum rotational speed, and power-up and current draw at 60°C and low pressure.
Low pressure compressor. An experimental map of an alternative compressor, held as a backup solution — a second answer developed before the first one is needed. Mock-up components were 3D printed to verify assembly and flow paths before anything was made for real.
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WHAT IT OPENS
A pressurisation system qualified for the stratosphere is a narrow thing to have built and a broad one to have learned: compressors, valves and instrumentation that keep working at −60°C and 7500 Pa, and the test capability to prove it.
It also puts NablaWave inside a European Defence Fund consortium led by Thales Alenia Space, working to the standards that sets — which is the kind of position a company holds rather than wins twice.