Grey skies and rain echoed the mood among aerospace and defence companies as the Paris Air Show opened.Marking the event’s centenary there are around 30 historic aircraft on show but it is the future that concerns the aviation industry with earnings slammed by the economic crisis and swine flu. The industry has also been shaken by the still-unexplained crash of an Air France Airbus over the Atlantic. Order announcements will be very limited this year but Qatar Airways has signed an agreement to buy 24 Airbus A320 jets. The Gulf carrier is doubling its medium-haul fleet preparing to fend off competition from low-cost carriers. Airbus and Boeing’s newest planes – the A400M military transport and Boeing’s 787 jetliner – are not at the show; both have been delayed by numerous production problems. And as the Paris show started, Eurocopter said it expects a downturn in orders from the military next year as the economic crisis cuts into budgets. The company, which is the world’s biggest civil helicopter manufacturer and a division of Airbus’ parent EADS, gets just over a third of its orders from the military sector.