CREATE TABLE table_16761 ("Race Name" TEXT, "Circuit" TEXT, "Date" TEXT, "Winning driver" TEXT, "Constructor" TEXT, "Report" TEXT)

what is the name of the constructor that has the circuit zeltweg airfield?
SELECT "Constructor" FROM table_16761 WHERE "Circuit" = 'Zeltweg Airfield'
SELECT "Constructor" FROM "table_16761" WHERE "Circuit" = 'Zeltweg Airfield'