Joe asked: Documentation for this? I read about the Bachem Flight in a book, and it said the same as kwp. As mentioned here earlier, the Bachem was unlike the A4 a more low tech device. Griehl, Manfred / Dressel, Joachim: "Die deutschen Raketenflugzeuge 1935 - 1945" Augsburg 1995 ISBN 3- 89350-692-6