Tuesday 20 November 2012

Horst Dieter Lux, KG 200 Mistel test pilot (part 1)

Above and below; 'Project Beethoven'  - the first Bf 109 F-4 (CI+MX) and Ju 88 A-4 Mistel combination, Ainring, early 1944

Vern Dander, a former Hughes test pilot from Colorado, has very kindly sent me some papers and photos from the personal archive of a former neighbour of his - Horst Dieter Lux. Horst Dieter Lux is a name that might be familiar to readers of Robert Forsyth’s impressive study of Luftwaffe ‘Mistel’ or composite aircraft development (Classic Chevron, 2001).  According to his own account Lux played a key role in the development of German ‘piggy-back’ aircraft, although how ‘key’ is not clear in the literature. Secondary sources in particular   ‘Die Geschichte der Huckepack Flugzeuge’ by Arno Rose ( Motorbuch 1981) quote Lux as being assigned to KG 200 on Werner Baumbach’s personal staff to oversee and coordinate Luftwaffe requirements and to develop a pilot training programme. This followed a period as TO with KG 30 and a close association with Dietrich Peltz.

 However his post-war employers in the US, Lockheed, describe Lux in their August 1977 in-house journal as a ‘civilian project director’ employed by Junkers;

Recent newspaper and TV reports of the space-shuttle orbiter riding piggy-back on a B747 brought back vivid 35-year old memories for Horst Lux of ASW Export sales. Horst, fresh from the Technical University of Berlin with a Masters in Aeronautical Engineering was placed in charge of a strikingly similar project for the Junkers company in Germany in 1942..”

This project was " Beethoven "  and was born as a more economical solution to the problem of destroying Allied shipping and high-value targets –  it had been estimated within Luftwaffe circles that each large enemy vessel sunk cost as many as 25 Luftwaffe bombers and their crews. Known variously as ‘Mistel’ – or ‘mistletoe’ as the two aircraft shared a symbiotic relationship, the piggy-back combo represented two major aviation ‘firsts’;
-    -the first time that an unmanned aircraft had been deployed as a ‘flying bomb’ guided to the target area by an attached fighter, 
          -the first use of the ‘fly-by-wire’ concept, the pilot in the upper aircraft operating the controls of the ‘carrier’ aircraft electrically..

The idea was that the lower craft in the composite arrangement carried a 3-ton charge and was flown to within five miles of the target by the fighter mounted above it on pylons. Once within close range, explosive bolts enabled the fighter to separate and return home while the lower component packed with explosives continued to the target at a selected glide angle – a huge unmanned flying bomb.

As the “project’s chief test pilot as well as its manager”, Horst Dieter Lux flew more than 180 aerial separations according to the Lockheed journal. For testing, a pilot was employed in the carrier airframe to land the machine. Lux wrote;

“  We would fly the bomber by wire to within five miles of the target, set its course using a special sight in the fighter, and release it. The automatic pilot in the bomber would then fly it the rest of the way to the target, keeping it on course and maintaining the selected dive angle..”

According to Lux’s own account three versions were tested and/or under development before the end of WWII;

Mistel I  - a Bf 109 F mounted on top of a Ju 88 A
Mistel II – a Fw 190 mounted on top of a Ju 88 G
a jet Mistel  - a Me 262 mounted on an Ar 234

 Post war Lux  wrote;

“  What I had learnt and researched during my Masters thesis on stability and control, especially flutter, made me an expert.  This was work that I carried out under the auspices of the Deutsche Versuchsanstalt für Luftfahrt or DVL at Adlershof (German Experimental Institute for Aviation). The test centre at Rechlin took more and more notice of my studies and when I had completed my degree I went to work there on dive testing and evaluation. Dive bombing was the only way to accurately deliver ordnance at that time. As the winter weather in northern Germany rarely gave us high enough ceilings to carry out our test work, my unit was sent to the sunnier climes of southern Italy at Foggia. This work brought me into close contact with Luftwaffe operations and it was there that I met 'Dieter' Peltz who was in command of an operation at Foggia training crews and pilots on new tactics. We became good friends. We spent a lot of time discussing how the high losses in bombers committed on convoy attacks in the Mediterranean could be reduced. The idea of the ‘piggyback’ was born..”

After Foggia Peltz was tasked with developing the use of pioneering types of  guided missiles then under development in Germany, such as the  Fritz X and Henschel Hs 293, also designed to be deployed against Allied shipping. Peltz moved on quickly and aged 28 became the youngest General in the Luftwaffe when he took over the bomber arm (General der Kampfflieger). According to Lux 'the 'Piggyback' idea lived on and Peltz subsequently asked Lux to serve as his "advisor and evaluation pilot ". When funds finally became available Pelz asked Lux to head up the 'Piggyback' development programme.

" ..It was a challenging programme - two aircraft, a fighter and a bomber, had to be mounted together, a fly-by-wire system developed so that the combined aircraft could be flown from the fighter cockpit and a large warhead (3.5. to of TNT) had to be mated to the nose of the bomber, replacing the cockpit..I made the first flight about two months after the start of the programme. The development of the fly-by-wire system made up the bulk of the flight test programme followed by stability and control tests to establish safe separation over a wide speed range. The single-channel fly-by-wire system was a hazard in itself and we were lucky if there were no upsets - mostly there were, ranging from sudden hard-overs to instability to explosive bolts which failed to explode...eventually the bugs were worked out and on D-Day five of my aircraft were prepared for their first combat sorties....."

to be continued....