The HWK 109-509.B motor was a test bed for the performance of a dual chambered rocket motor. Although Messerschmitt were busy working on new proposals for a suitable airframe, flight tests were required. The 109-509.B motor was available from the first part of 1944, so two standard Me.163B airframes were modified to carry the larger motor.

The picture on the left shows the Messerschmitt Me.163B V18 VA+SP making a rocket powered take-off. Compare it with the view of the modified Me.163 V6 shown below, making a sharp start at Peenemunde.

Messerschmitt Me.163B V6 was largely the same as standard Model B Komets, but with the exception of a modified keel line, shortened landing skid and a retractable tailwheel with fairing doors. The tailwheel itself was set further forward on the underside. The rear fuselage at the point where the second combustion chamber emerged was (inelegantly) deepened and widened.

For the pilot, the cockpit must have been modified, although to what degree has not yet been discovered. However, modifications along similar lines to those proposed for the 8-248 (Junkers Ju.248 aka Me.263) with secondary chamber pressure indication and of course a second control lever set near the throttle quadrant must have been made.

The picture on the left shows Komet V6 making a sharp start. It shows the relocated position of the faired tailwheel and the deepened rear fuselage.

Me.163B V18

For many years, William Green's 1971 book "Rocket Fighter", was one of the few on the market to give a detailed history of the Me.163. In it he describes how two Me.163s, BV6 and BV18 were modified to carry the new Walter motor with auxilliary combustion chamber. He goes on to detail how, on 6th July 1944, test pilot Rudolph Opitz flew Komet V18 out over the Baltic with "both rocket chambers functioning" [p110]. The text is quite unequivocal, and with figures for heights and speeds (Green describes how the flight instrumentation was filmed during the flight) he tells how the flight began normally enough, but that the rate of climb began to increase rapidly with Opitz soon finding himself exceeding the critical Mach number of the aircraft at above 16,000 feet.

Opitz cut power to the motor, causing a steep dive from which he only just managed to recover. It was later determined that V18 (sic) had reached a speed of 702 miles an hour. Upon landing back at Peenemunde the text describes that it was found that the aircraft had almost completely lost its rudder, as shown in the picture included here, and shown on page 115 of his book.

However, Ransom and Cammann's more recent book (2002) shows the same illustration of BV18's rudder on Volume 1, Page 97, but, they say, from a flight of 23^rd December 1943, by Heini Dittmar, and although this airframe was later used for assisted take-off rocket tests, they state this did not begin until 7^th July 1944.

The Ransom and Cammann work is very thoroughly researched from the archives, and one is inclined to their view of the facts, possibly backed by an extra thirty years in which additional source material may have become available. Without any reflection on William Greens' work, this confusion goes to show that whoever the original author, the researcher should be wary of reproducing a single source as a definitive opinion.

References.

1	Green, William: Rocket Fighter Purnell's History of the Second World War: Weapons Book No.20 1971
2	Ransom, S and Cammann, H-H: Me 163: Rocket Interceptor. Volume 1 Classic Publications 2002

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