Flyboys (12A) <!-- none onestar twostar threestar fourstar fivestar -->

There have not been enough First World War flying aces in the movies. Ever since William Wellman's 1927 epic Wings won the very first Academy Award for Best Picture, film-makers have, by and large, steered clear of the aerial battles that raged over the Western Front between 1914 and 1918. One of the few that stick in the memory is Malcolm McDowell in Aces High (1976), which transposed RC Sherriff's play Journey's End to the skies; in the intervening 30 years cinema has more or less ignored them. We've had to make do with Snoopy's Red Baron obsession in Peanuts and the mad Lord Flashheart in Blackadder Goes Forth.

So the idea of a big-budget recreation of those dramatic aerial dogfights - when white-scarfed daredevils apparently relied on just a wing, a prayer and a plane made out of balsa wood - should provoke a chorus of "goggles on, chocks away and tally-bally-ho, chums!". Or something like that, at least.

Flyboys, as it turns out, puts a dampener on that enthusiasm very quickly, and must count as a genuine opportunity squandered because, for all the technical expertise brought to bear, it feels practically untouched by human life. The film purports to recount the heroic account of the first American fighter-pilot squadron to see action in the First World War, and yet, for most of its duration, I remained unsure as to whether this elite corps was an invention or not.

One reason, probably, why Hollywood has shown decidedly little interest in this period is because the United States of America did not enter the Great War until 1917. Yet Flyboys, set in the year before, tells of American youths arriving in France to help the Allied war effort. Is this an early warning of historical licence? In fact, they are all volunteers, come to join the Lafayette Escadrille under the command of the French captain Thenault (Jean Reno) and, in the hands of the scriptwriters, they trail quite varied backgrounds.

The Texas cowboy Blaine Rawlings (James Franco) is evicted from his family's ranch and sees his future in a newsreel reporting the squadron's battles. William Jensen (Philip Winchester) is the son of a cavalry officer and determined to continue the family's military tradition. Eddie Beagle (David Ellison) is a desperado who can't shoot straight, while Briggs Lowry (Tyler Labine) is an ex-Harvard scapegrace with a point to prove to his disappointed father. Eugene Skinner (Abdul Salis), a black American boxer who wants to fight for France ("this country's been good to me") seems on first sight the most flagrantly invented character of the bunch, a mere nod to correctness - and yet he's based on the real-life Eugene Bullard, the first-ever black fighter pilot.

Overseeing this motley band is the squadron leader Reed Cassidy (Martin Henderson), the battle-hardened ace who at first shows more affection for his pet lion (the squadron mascot) than for these callow recruits. This offhand attitude is, apparently, also true to life; because new pilots had a life expectancy of about six weeks, veteran fighters tended to ignore them. Why should they bother befriending dead men? Cassidy himself is based on Raoul Lufbery, a Frenchman born in the US who became the squadron's first ace.

The information on these real-life flyers, detailed in the end titles and photographs, sits very awkwardly in the light of the film itself.

Aside from the dogfights, whose sound and fury director Tony Bill, himself a pilot, captures quite magnificently, there's barely a moment on the ground that you could call authentic. The script carries no trace of period resonance, and the acting is brought down to its level. "We're knights of the sky!" one of them cries, which might have made a good title for the television mini-series which this might so easily be, with photogenic locations (the squadron appear to be billetted in a palace that could rival Versailles) and galumphing narrative rhythm.

The film's two genuine stars are wasted. Reno gets no purchase at all on the French captain whose attitude to his American charges is never explored. Franco, who has a great movie face and a slouch learnt from James Dean, spends much of his time on-screen in a maddeningly soppy romance with a French woman, Lucienne, who has become a surrogate mum to three orphaned moppets. Franco and the French actress Jennifer Decker look rather sweet together, but their sexless mooncalf innocence wears very thin over two and a bit hours.

As Franco's mentor, Henderson does a lot of tough-loner whisky-drinking - he's always lurking in the bar, even when there's no one else there - and, like the rest of the cast, doesn't seem to be playing a human being. Much as you'd like to feel involved in his grudge rivalry with the German ace "the Black Falcon", you don't for a minute believe that he knows one end of this evil Fokker from the other.

Will a younger audience respond to the aerial derring-do? It seemed to me a hundred times more dynamic than anything in last week's Pirates of the Caribbean, and conveys a very immediate sense of how close to death these duelling pilots came every time they went up in their "kites". It was also news to me that pilots carried revolvers with them, in case they preferred a quick death to being burnt alive in the cockpit. If the film had concentrated as much energy and know-how into the script as the pilots do into the fighting then Flyboys might have been the stirring experience it clearly wants to be. Instead, one reads those closing credits about the heroes of the Lafayette Escadrille in a kind of shocked bafflement. How can a drama so deeply rooted in military courage offer so little of real life?