Upward firing weapons were actually used in a number of fighters - originally in WW1 for attacking zeppelins:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Schr%C3%A4ge_Musik" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Schr%C3%A4ge_Musik</a>