* Boeing seen launching larger 787 with up to 100 orders
* Airbus seen netting hundreds of orders
* Low-key U.S. military presence due to spending cuts
* Embraer likely to upgrade regional E-Jet
Leading planemakers are battling over strategy for big jets as the Paris Airshow gets underway on Monday.
After a bruising two-year fight for market share of popular smaller models, Airbus and Boeing Co are increasing the deployment of next-generation long-range jets, seen as crucial to the future of both companies and their suppliers.
Days after it surprised the industry by making the first flight of its new A350 just in time for the show, Airbus will attempt a curtain call on Friday with a fly-by for President Francois Hollande, on only the plane's third test.
"People are focusing on long-haul aircraft this year. It is a crucial segment and a fundamental one for the profitability of both constructors," said Bruno Goutard, sector economist at credit insurer Euler Hermes which has a key role in aviation.
Boeing said last week it sees a $1 trillion market over the next 20 years for mid-sized, twin-engined passenger jets, a category that includes its 787 Dreamliner.
Europe's Airbus and its U.S. rival have placed bets worth tens of billions of dollars on the success of this market.
Behind them Canada's Bombardier Inc is betting the same technology will be suitable for smaller planes as it seeks to boost orders for its new CSeries, due to fly this month.
Brazil's Embraer is expected to announce an upgrade and possible fresh orders for its regional E-Jet.
For Boeing, the latest addition to its fleet, the 323-seat 787-10, is partly designed to serve dense routes within Asia -- a region fast emerging as the world's largest travel market.
The company claims it will have the best economics of its kind, while Airbus sees it as a repeat of a previous 767 flop.
Boeing re-introduced the 787 Dreamliner to service in April after a three-month grounding due to battery problems. Now it is also looking at a partial redesign of its 777 mini-jumbo too.
The decision to go ahead and build a new 787 version, backed by up to 100 orders spread between five or six launch customers, is expected to be announced at Le Bourget on Tuesday. Some orders may be converted from existing demand for smaller jets.
"We have no comment but we are having discussions with our customers about the potential for the 787-10X," a Boeing spokesman said, referring to the project's working name.
Leasing companies are at the event in force and could continue placing orders for narrow-body planes like the Boeing 737 MAX and the A320neo, as the civil side of the industry looks beyond the financial crisis and focuses on emerging markets.
Lufthansa could confirm an $11 billion order for over 100 Airbuses. Air France may confirm an order for 25 A350s after resolving disagreements with engine maker Rolls-Royce Holdings Plc as the planemaker targets a "few hundred" show orders this week.
Breathing life into recently slow sales of the world's largest airliner, Airbus could win a double-digit order for the A380 superjumbo from Doric Asset Finance, industry sources said, confirming a Bloomberg report.
The military side of the world's largest aerospace event looks set to be quiet by comparison with previous years.
U.S. companies have scaled back but all eyes will be on the return of Russian fighters, noted for striking manoeuvres.
Budget cuts prevented the U.S. government from bringing F-16 jets, which usually show off their skills during the air show.
Lockheed Martin Corp, maker of the F-16 and F-35 fighter jets, did not bring even the mock-up model of the F-35, the Pentagon's largest program which faces concerns about costs.