Francis Ford Coppola and Apocalypse Now

From Musician article in 1981, Addendum #1:

along with with bassist Phil Lesh, Airto, Flora Purim and others, accepted a
commission from Francis Ford Coppola to compose the score for Apocalypse Now: The Rhythm Devils Play River Music. 

Hart's marching orders from Coppola were short and to the point: "All
Francis said was 'you know what I want¿you know how to make
magic.  Do it!"' recalled  Hart. "I watched the film constantly. I had it
on video cassette in my kitchen, in my bedroom, and in the studio. It
played  continuously for three months." Their task was complicated 
by the fact that the battle sound effects Coppola brought back from
the Phillipines sounded unconvincing. In the end they were asked to
find a way of simulating the cacophony of war in the studio. "Try
reproducing the sounds of a napalm attack using wooden instruments
and bells;" suggests Hart wryly.  "The artillery sounded like cheap
firecrackers, so we had to reinforce that, too, with steel drums I
had built, and other  percussive devices. We had over fifteen hours of
material!"