What number is in Bois de Warville with a time less than 810?
CREATE TABLE "verified_aerial_victories" (
  "number" real,
  "time" real,
  "aircraft" text,
  "opponent" text,
  "location" text
);
SELECT SUM("number") FROM "verified_aerial_victories" WHERE "location"='bois de warville' AND "time"<810;