Three Pilots to Pole a Parabola

Chris Long looks at the unique training services offered by French company novoSpace.

As Jean-Francois Clervoy, a three-time NASA Shuttle astronaut, well knows, there is still a lot of research to carry out into the effects of zero-g. For decades, part of that task has been carried out inside aircraft which can fly a parabola which results in zero g, albeit for a period measured in fractions of a minute.

He started out with the NASA KC135 which was used for zero g flight, and, on his return to France, together with another expert, Dr. Ir Vladimir Pletser of the European Space Agency (ESA) became involved in the use of an Aerospatiale Caravelle for the same purpose. Other aircraft have followed on from this, and once he had started up novoSpace in Bordeaux, France, they used an Airbus 300 for research by European agencies. The work now continues with a new airframe, an A310, which was formerly a VIP aircraft operated by the German Luftwaffe on behalf of the German Government. This low-time aircraft (it has about 7000 hours of flight time) has just completed its first working flight from its home base at Bordeaux Merignac airfield with some 40 scientists on board.

Value

Whilst there is considerable value in simulation, including the weightless operation and training of astronauts in a large swimming pool, that situation has its limits. For instance, whilst free to move in all axes in neutral-balance, the blood in the human body will still run to the head when the trainee is upside down - gravity has not been switched off. The range of studies in the aircraft is wide - amongst the disciplines are research into biometric, physiological and technological effects in weightlessness.

There are several training elements embodied in this programme - the demand for astronaut training has reduced in recent years, but, for instance, testing of ingress and egress for suited astronauts using new hatches or suits can be carried out, as can docking manoeuvres for units like the recently-retired ATVs. Given that the project is largely sponsored by the French research Agency, the CNES, the European Space Agency and the German research agency the DLA, a new generation of scientists can be trained when access is given to students working on selected projects for those working for PhD’s or Masters qualifications. Here the advantage of a lower cost alternative to space-born projects becomes clear. Young scientists typically have to wait 5-6 years to get access to space vehicles. With novoSpace, selected students can actually get on a flight with their project within a year - and so can complete their thesis on time.

To get the most benefit from the profile requires very accurate piloting. Some basic limits are those imposed by the aircraft manufacturer, including maximum speed authorised and maximum and minimum “g” loadings. Working within those parameters typically gives a 22 sec period for zero-g. Interestingly, by modifying the profile it is possible to reproduce other “g” levels, for instance replicate Martian gravity - that gives 35 seconds, or even Lunar gravity so that one can become accustomed to walking on that surface.

Flying

So, how to fly such a tricky parabola? The good news is that the aircraft required no system or structural modifications, but there was a need to provide additional instrumentation to guide the pilots. Inset in the image is a display which gives a vertical strip indication of, on the left, Angle of Attack, the central strip is a “g” meter, and on the right an expanded (10x) ”g” meter. The aircraft has to be flown to zero “g” +/- 0.05 “g”. The profile of the parabola, requiring an initial pitch to 50 degrees nose up, is shown here.

That task is demanding, so the crew of three pilots divide the responsibilities. The pilot in the left hand seat only flies the pitch attitude - he operates the control column with a fixed “handlebar” attached to the standard column so that he cannot introduce any roll input. In the right hand seat the roll is controlled by straps attached to the ends of the conventional control column so that very small inputs in roll can be made. The final team member sits between the two pilots, and is exclusively tasked to maintain the desired power setting. The whole is overseen by the pilot in the right hand seat.

How do you train the pilots in this technique? As might be obvious, you need to start with highly skilled and experienced pilots. Historically these have all been test pilots - for instance the Chief Pilot, Eric Delesalle, is currently the Head of the Flight Test Department at the Toulouse-based ATR. With the introduction of the A310, two more pilots from the French Air Force have brought their considerable experience on type to the team. Typically the crews train together on a developmental full flight simulator in Toulouse for two sessions, and then, depending on experience, either one or two training flights on the aircraft. Normal currency checks for civil registered aircraft are, of course, essential, and the flying rate is, typically, 30 flights per year. Each flight comprises approximately 30 cycles of the parabola.

This aircraft and its performance fill a very specific role, but, in an innovative twist, not only does it achieve its baseline scientific goals, but on six flights every year, it also flies selected members of the public, who, for a relatively modest charge, can experience this wonder themselves. Not only does this bring in a little revenue to help offset the operating cost, it importantly serves as an excellent medium to spread the word about this extraordinary project.