On 13 June 1918 a raid destroyed 6 Belgian Hanriot Hd.1 at the De Moeren air base. Willy Coppens found that the 5 tones camouflage of the replacement machines, adopted in October 1917, made them look too much like "toy snakes" and had his machine totally repainted in cobalt blue. Soon later, Coppens adopted the same color for his reserve plane. So Coppens flew at least two blue Hd.1, serials HD 6 and HD 23: the latter also had a fireproof Larsen tank. ESo he gained the nickname of "Démon Bleu" (Blue Devil).
Willy Coppens has been the first Belgian pilot to use the Hanriot: he received the very first one arrived at De Moeren on 22 August 1917 and refused by all his comrades. Thanks to the Hd.1, Coppens became the first Belgian ace with 37 victories, 35 of which against balloons.
Coppens experimented with weapon variants. The standard central machineguns on Belgian planes, instead than set off to the left as on Italian planes, derives from his experiments. As he told in his memories "Jours Envolés", when he first wanted to try a two MGs arrangement he was heavily wounded before managing to do it. Later the ace André De Meulemeester convinced him that it was not worth. Later again, Coppens tried anyway the twin MGs on his Hanriot, from the 23rd to the 25th of october 1917, but he immediately replaced them with a 11mm Vickers MG fit to use some incendiary bullets that he got from a French colleague, expecially suited for his "balloon busting" missions.
A camouflaged Hanriot Hd.1 painted as one of Coppens' planes (serial number HD 75) is at the Royal Air Force Museum of Hendon, London. Late in his life, when he visited the Musée Royale de l'Armée of Bruxelles, Coppens said that he halso flew the Hanriot there preserved, HD 78.
Historical notes above come from "Hanriot HD.1/HD.2" by Gregory Alegi, Windsock Datafile n. 92, March 2002.
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