* Boeing to sell 777s, Airbus to sell A320s at show's open
* Painted paw prints kick off week-long marketing battle
* EU seen appealing subsidy ruling at same time as air show
By Tim Hepher and Andrea Shalal-Esa
FARNBOROUGH, England, July 19 (Reuters) - Large Boeing (BA.N) jets and short-haul plane orders from Airbus EAD.PA look set to dominate the opening of the Farnborough Airshow on Monday in a test of fledgling economic recovery.
Boeing could grab a $5 billion order from Emirates for 20 777 big passenger jets and aviation industry sources said they expected its European rival Airbus to chalk up sales of its A320 single-aisle aircraft even as it considers upgrading it.
The orders are part of a tentative upswing in civil aircraft demand, driven mainly by emerging markets and low-cost carriers.
Commercial sales look more promising given double-digit growth in air traffic, but lingering concerns about the broader economy are keeping many analysts cautious.
"The traffic numbers themselves are excellent, but there's all this uncertainty and doubt about the strength of the recovery in the background," said Richard Aboulafia of the Virginia-based Teal Group.
Farnborough hosts the massive aviation and arms jamboree every other year, rotating with Le Bourget near Paris.
For a week the quiet Hampshire town in southern England will be transformed into an armed camp bristling with both the latest smart weapons for arms buyers and shiniest new passenger jets.
Probably the star attraction will be the Boeing 787 Dreamliner, a plane now in testing and built from composites. It arrived on Sunday, thrilling crowds of aviation enthusiasts.
The aircraft promises greater fuel efficiency and its lightweight materials and innovative design have captured public imagination. But glitches have delayed it more than two years.
Airbus will be showing off its A400M military transporter plane and attempting to draw a line under its own delays and cost overruns with a marketing ploy over the plane's name.
Pilots nicknamed the plane "Grizzly" when it took off for the first time last December and workers were seen spraying the paw prints of a grizzly bear over the airfield's grounds on the eve of the show, as Airbus prepared to baptise the test plane.
Britain's Royal Air Force has so far, however, ignored the name and has not decided what to call the plane, leaving marketers with a headache but hoping their name will catch on.
Marketing stunts are a classic feature of air shows but are just the tip of the iceberg in an increasingly bitter feud between the top plane makers over trade, defence and jet orders.
Boeing says a World Trade Organisation report issued last month means European nations must rectify illegal subsidies paid in the form of loans to Airbus for plane development projects.
The European Union will launch an appeal against the decision on Thursday, two sources familiar with the case said.
The same companies are locked in an ill-tempered contest for a $50 billion deal to supply tankers to the U.S. Air Force and each is likely to press its case to worldwide media at the show.
Boeing and Airbus parent EADS also vie alongside other U.S., Russian and European players for fighter sales.
Eurofighter, in which EADS has a stake, will announce plans this week to invest in a new electronic radar to help it bid in a contest for 126 jet sales in India, defence sources said. The race is attracting most of the world's large defence firms.
But a decision on whether to upgrade the most popular ranges of Airbus and Boeing passenger aircraft with new engines, a big gamble for either company, will not be ready for the show.
While the two aerospace giants hog most attention, Canada's Bombardier (BBDb.TO) is likely to announce at least one order for its C-Series plane designed to chip at Airbus and Boeing.
Much of the real business done or prepared at the show will be in invitation-only chalets of defence companies, even though several have reduced their presence to display belt-tightening, and arms makers are bracing for heavy Western defence cuts.
Sikorsky, a unit of United Technologies (UTX.N), expects a significant first order this week from a Middle Eastern country for the international version of its Black Hawk helicopter.