I assume you mean inspirational ones, since that appears to be what you are using them for, but here's a few, with one or two that are maybe not inspirational, but undoubtedly quotable:
'Always above, seldom on the same level, never underneath' -
Edward Mannock (note that this is sometimes written as 'never below' which is a bit more catchy)
'Until one has given everything, one has given nothing' -
Georges Guynemer
'I hope the bastard burned all the way down' - Edward Mannock (this one in reference to MVR, upon hearing of him being shot down and killed)
'If it had not have been for his helmet and goggles, I could have seen what sort of face he had'
Manfred Von Richthofen (on his fight with
Lanoe Hawker)
'At one point he waved to me' Manfred Von Richthofen (again referring to Hawker when in combat with him)
'I saw British Tommies waving from a trench to me, and I felt much braver than I did a few minutes before'
James McCudden (on his engine faltering after a combat and him barely making it back over the lines)
'Those Huns were artists' Edward Mannock (not what people normally imagine he would say)
'I hadn't time to observe him hit Mother Earth, as things were happening' Edward Mannock
'Are you ready to die for your country Taffy? Will you have it in flames or in pieces?' Edward Mannock (a greeting to
Ira Jones)
'I shall never rest content, 'kill or be killed' can only be my motto' Ira Jones (upon hearing of Mannock's death)
'One of my guns jammed, but the other one shot all the better'
Oswald Boelcke
'Everyone ran in the direction of the dugout, I thought to myself that it was safer to be in the air, and dashed off' Stefan Kirmaier
'I could have hugged him when he asked whether I wanted to go to the Somme with him' Manfred Von Richthofen (on being asked by Boelcke to join Jasta 2)'
'If I had to be shot down, I'm pleased that it should have been by so good a man' Captain RE Wilson (on being shot down by Oswald Boelcke)
'I was rather proud of that one wing, but more determined than ever to win the double wings of a fully-fledged pilot'
William Bishop (on his initially being an observer)
Al