* Boeing launches 737 MAX 10 with flurry of orders
* Lockheed close to $37 bln-plus deal for F-35 warplane
* French President Macron gives boost to troubled A400M (Adds confirmation from Boeing. Macron's arrival)
PARIS, June 19 (Reuters) - Boeing unveiled a new member of its best-selling 737 aircraft range, injecting new life into a faltering civil aviation market as French President Emmanuel Macron flew in to open the Paris Airshow on Monday.
After years of booming orders, driven by rising air travel and more fuel-efficient planes, passenger jetmakers are bracing for a slowdown in demand while they focus on meeting tight delivery schedules and ambitious production targets.
But Boeing generated a fresh burst of activity at the world's biggest airshow by launching the 737 MAX 10 to plug a gap in its portfolio at the top end of the market for single-aisle jets following runaway sales of European rival Airbus' A321neo.
The U.S. planemaker said it had more than 240 orders and commitments from at least 10 customers for the new plane, which can carry up to 230 people in a single-class configuration.
"The MAX 10 is going to add more value for customers and more energy to the marketplace," Boeing Chief Executive Dennis Muilenburg said at a presentation ceremony.
But industry sources said Airbus would immediately hit back with a large order for the A321neo.
People familiar with the matter said on Sunday Airbus was also close to clinching a roughly $5 billion deal with low-cost carrier Viva Air Peru.
Airbus will announce an order for 10 of its A350-900 wide-body jets as well, industry sources added.
While demand for passenger jets may be faltering, there are signs interest in military aircraft is picking up after years in the doldrums due to budget cuts and weak economic growth.
Lockheed Martin is in the final stages of negotiating a $37 billion-plus deal to sell 440 F-35 fighter jets to a group of 11 nations including the United States, two people familiar with the matter told Reuters.
That would be the biggest deal yet for the stealthy warplane, set to make its Paris Airshow debut this week.
In another boost for a defence project, French President Emmanuel Macron flew into the show on an Airbus A400M military transporter in his first official engagement since winning a parliamentary majority in elections on Sunday.
His arrival was followed by a flypast by the world's largest passenger plane, the Airbus A380, and France's aerial display team.
The ceremony lent high-level support to two ambitious European aerospace projects tarnished by problems in recent years: the A400M because of chronic cost overruns and delays and the A380 because of weak sales that threaten its future.
Airbus said on Sunday it was working on an upgrade of the A380 - called A380plus - with fuel-saving wingtips, confirming plans reported by Reuters in March.
Boeing, however, is expected to say at the Paris show that demand for mammoth planes such as the A380 and its own 747 is moribund. (Additional reporting by Vicki Bryan; Editing by David Clarke and Mark Potter)