Mistel composite controls

Discussion in 'Aviation' started by Geedee, Dec 30, 2012.

  1. Geedee

    Geedee Well-Known Member

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    Chaps, it not very often I post teckkie type questions for you to hopefully answer, but yesterday, while having furkle around on F*ceb**k, I came across a picture of Mistel composite comprising a Ju 88 with the fuselage front replaced and a large 'probe'...I'm assuming this is the detonation device ?... out front, and Fw190 perched up on top. Of interest...and I'm still trying to find the photo so I can post it for you guys...was the fact that the 190 looked like it had a torpedo underslung between it legs !. It was long and thin....loked about two feet in diameter and ran from the firewall to about half way along the fuselage... and didn't look like a drop tank !

    However, I'm digressing again. My tekkie type question is... does any one have info on how the lower part of the composite was controlled ?.

    I mean, there you are strapped into a 190 and you have your normal fighter controls, but what controls...if any... where duplicated for the bomber underneath ?.
    ...Where there seperate controls for the engine management systems...pitch / mixture / throttle etc.
    ...How was the bomber undercart operated.
    ...Were the bomber control surfaces locked in neutral and it was upto the parasite fighters controls to make the thing go up / down, left and right ?.
    ...If not , what was the interface ?
    ...How did the guy in the fighter control the power output differences between his fighters engine and the bombers ?

    Also, I'm assuming that some brave soul / nutcase, had the enviable task of taking one of these bad boys up for the first time and possibly returning it back to the ground as complete unit...sort of flight test ?...wonder if there's any 'Pilots notes out there.

    Any ideas?

    If any-one knows, it'll be you guys :thumbright:
     
  2. bobbysocks

    bobbysocks Well-Known Member

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    #2 bobbysocks, Dec 30, 2012
    Last edited: Dec 30, 2012
    is this what you are talking about???

    Ju88_mistel.jpg

    this is what i found...

    check out page 50 of this preview of a book..

    http://books.google.com/books?id=lU...nepage&q=ju 88 mistel guidance system&f=false

    also

    from JUNKERS JU 88 "MISTEL"

    Early in 1943 the idea took on a new form: a piloted Bf 109 fighter mounted on top of an unmanned explosive-laden Ju 88 bomber by means of supporting struts. This was the Mistel. The pilot in the upper machine was to control the combination; when he got to the target he would put the combination into a 15 degree descent and aim the whole lot at the target. At a range of about three quarters of a mile from the objective he was to separate his fighter from the lower component and climb away, leaving the latter to fly straight on under control of the automatic pilot until it impacted. The fighter pilot was then to return to base in the normal way.

    Thus far the Mistel idea had little to commend it, for the expenditure of one Ju 88 bomber to deliver a mere 3 ton warhead to a target was a grossly uneconomical method. But if a special warhead could be fitted to the explosive aircraft, a warhead which could punch through almost any protective layer of armor, the possibilities became very attractive.


    THE HOLLOW CHARGE

    The warhead fitted to the Mistel was of the hollow charge type. Such warheads were used a great deal during the war against tanks. But with the Mistel a hollow charge warhead weighing 7,700 pounds - far larger than any built before or since - was to be used. Below is an early Mistel 1 combination, with the hollow charge war- head fitted in place of the crew compartment of the Ju 88 lower component. This warhead, seen below on a Mistel 1, was capable of "drilling" a hole clean through the hull of even the most heavily armored warship.

    The hollow charge, as fitted to the Mistel, was intended to blow a hole through the thick steel armor of a battleship. The shape of the 3,800 pound explosive charge was important. At the front end of the explosive charge was a cone-shaped hollow cavity which was lined with a layer of soft metal-either copper or aluminum. It was important that a soft metal be used for this liner, since a harder metal would prevent the hollow charge action from developing properly. Four electrical crush fuses, for firing the detonator of the main charge, were mounted at the end of the nine foot long stand-off probe which protruded from the front of the warhead; the detonator for the main charge was situated at the rear of the warhead. When the stand-off probe hit the target the crush fuses operated, set off the detonator, and thus fired the main charge. Because of its shape and the fact that it was burning from the rear forwards, the force of the main charge was focused on to the soft metal liner. The liner became fluid, and was pushed forward from the centre of the cone in a fine jet. A split-second later the hollow charge action had developed completely. The metal in the liner was now "squirted" forwards in a stream about one foot in diameter, a stream which reached speeds of between 20 and 2.5 times the speed of sound. Thus the hollow-charge acted as a "gun", and the soft metal liner as a "bullet". The colossal speed attained by the thin jet of soft metal gave it the energy necessary to "drill" a hole clean through steel armor with a thickness of up to four times the maximum diameter of the warhead itself; in the case of the six foot diameter warhead fitted to the Mistel lower component, this gave a theoretical maximum penetration of the order of 24 feet. Such a warhead would I penetrate the heaviest armor carried by a ship with ease. Once through the outer protective shell of the target, and now confined inside it, the jet of high energy metal would vaporize anything in its path.


    The stand-off probe was necessary to set off the main explosive charge at the optimum distance from the target, so that the soft metal liner had time to form itself into a thin jet before it struck. Within limits, the further the charge from the target when it was detonated, the thinner and deeper the hole "drilled"; the closer the charge to the target, the wider and shallower the penetration. Both long and short stand- off probes were used with the Mistel. The entire hollow-charge action took place within one ten-thousandth part of a second, during which time a relatively slow-moving Ju 88 explosive aircraft, impacting at 400 m.p.h., moved forwards about a half an inch. This, then, was the potential of the Mistel device.


    The Ju 88 used for the Mistel program had their crew compartments removed at the after bulkhead, then these were re-fitted in place by means of quick-release fasteners. For ferry and training flights both the upper and the lower components were manned. At the last possible moment before an attack, the crew compartment was removed for the last time and the deadly hollow-charge warhead fitted in its place. This task required six mechanics, two armourers, and four ton capacity crane, and took one day. The process had an air of finality about it, for once the warhead-fitted Mistel had taken off the fighter pilot could not land the combination; whether it reached the target or not, the Ju 88 lower component was doomed. A series of aiming tests against cliffs on the Danish island of Moen proved the feasibility of the weapon.

    TRAINING

    Mistel pilots began training in April 1944, using the first two prototypes. Each man completed ten flights without releasing the lower component, then three flights each with a release. The pilots found that the poor view forwards from the fighter cockpit made the initial part of the take-off run difficult, and this ruled out the possibility of night take-offs. However, once it was airborne they found the Mistel easy to fly, if a little sluggish on the controls.


    Mistel combinations were put together using a number of different types. The original employed the Bf 109F and the Ju 88A, later ones employed various sub-types of the Fw 190 and the Ju 88. Versions projected but never assembled comprised an Me- 262 jet fighter on top of a Ju 287jetwmber, and an He 162 jet fighter mounted on an Arado E 377 A flying bomb.

    THE "IRON HAMMER" PLAN

    "Operation Iron Hammer", the planned blow to knock-out the Russian armament industry, had first been mooted at the end of 1943. The key targets within Moscow and Gorky were judged to be the steam and hydro-electric generating stations. It was known that the Russians lacked the plant to produce such turbines - most of the equipment scheduled for attack under the "Iron Hammer" plan had been supplied by the Germans before the war. As a result the Luftwaffe planners felt that the Russians would not be able to effect repairs for a very long time. But before the plan could be put into action the Russians overran the advanced bases which were to have been used. Now the targets lay beyond the range of the He 111.

    For the operation specially modified Mistel combinations were prepared, able to cover the 760 mile distance from the base airfields to the targets. The Fw 190 upper components were each to carry two drop tanks for fuel, and additional tanks for both fuel and oil. Following tests held at Udetfeld with the warhead, it was calculated that two hits with hollow- charge fitted Ju 88's would be sufficient against the smaller power stations, while six hits would be necessary against the larger ones.
     
  3. bobbysocks

    bobbysocks Well-Known Member

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    and finally this...

    from Mistel

    This system had required special techniques, particularly the electric flight controls that permitted the pilot to fly the transporter from his guiding fighter. The guiding fighter was mounted on steel struts and separation was obtained by mean of explosive bolts.

    Takeoff was made on three engines, with the fighter pumping its fuel from the JU-88 ensuring the return trip requirements (this system did not work when the Focke-Wulf FW-190A was used because its engine required a different fuel octane). The flight was initially made at low altitude to avoid radar detection, and at a distance of four kilometers from the objective, the "Father and Son" climbed to 800 meters.

    For the attack, the pilot established a 30 degrees dive at a speed of 650 kilometers per hour. Once the target was well acquired in the aiming sight, the Ju-88 auto-pilot was engaged by mean of the electric control, and one of the jettisoning bolt was exploded to place the fighter in a slight nose up attitude in reference to the transporter. Then, the pilot exploded the remaining bolts to free himself and return to base
     
  4. stona

    stona Well-Known Member

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    #4 stona, Dec 31, 2012
    Last edited: Dec 31, 2012
    The hollow charge warhead,known as the "elephantenrussel" (elephant's trunk) was developed by a company called Lauchhammer based about 50Km from Leipzig. It's proper designation was SHL (schwere hohlladung)3500. It contained 1700Kg of explosive,70% Hexogen/30% trinitrotoluol. The "probe" at the front,containing four electrical crush fuses,varied in length depending on the target. It was longest,2.75m,for use against armoured steel targets.

    The combination was controlled from the upper element. The throttle controls for the Ju 88 were mechanically linked to levers in the upper aircraft and limited engine instruments were duplicated. This took the form of two dual function dials indicating manifold pressure and rpm of the Ju 88's engines.Limited other controls were duplicated.The throttle linkage was supplied by the DUZ company.

    I have a photograph of the cockpit of the Fw 190 part of a Mistel 2 combination in which the switches for things like the Ju 88's undercarriage switches and indicators,autopilot controls,etc are visible.

    The other flight controls were electro-mechanically controlled. The Ju 88 was fitted with a modified Patin PDS (Patin-Dreierrudersteuerung) three axis control system.

    The PDS system allowed the combination to be controlled in two modes.In "cruise" mode control movements made by the pilot in the upper element were measured by a potentiometre and transmitted electrically to the servos linked to the flying surfaces of the Ju 88. This mode was also used for take off and worked well. One report noted:

    "Tests successfully demonstrated that the servo system gave the pilot the impression that his control column and rudder pedal were mechanically linked to the control surfaces of the aircraft beneath him,though this was not the case.These tests also showed how,in the future,large and very fast aircraft could be flown under conditions where control forces are likely to exceed the strength of the pilot."

    Something to remember next time you board a modern "fly by wire" airliner!

    In "automatic" mode the flight condition of the Ju 88 could be controlled by switches fitted to the upper aircraft's control column and instrument panel.

    Once seperated the Ju 88 flew on its auto pilot to the target. It was initially aimed from the upper aircraft using a revi gunsight and that information locked into the auto pilot. It was important therefore that the two elements of the composite were accurately aligned. A Junkers report noted:

    "Care must be exercised with the mounting of the upper aircraft to ensure that no deviation to the approach to the target arises after seperation because the lower aircraft will miss the target."

    On test or training flights both elements were piloted. This enabled them to land seperately after seperation. The combination,even with strengthened undercarriage,wa just capable of take off,but not a landing.

    The original combinations used the feed from the drop tank in the upper element to accept fuel pumped from the Ju 88. The idea was that the upper aircraft would seperate on full internal tanks in order to get home. This was not the case with later versions. I have seen pictures of Ju 88/Fw 190 combinations in which the Fw 190 clearly has a 300l drop tank fitted. The long,faired,ETC rack common to Fw190s is also therefore fitted.
    I think you are probably seeing some kind of fuel tank on the Fw 190 in the photo.

    Cheers

    Steve
     
  5. mike siggins

    mike siggins Member

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    was any acutaualy used in combat is there any pictures of the cliff they hit in practice
     
  6. stona

    stona Well-Known Member

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    They were,with limited success (politely). I'll dig out some details tomorrow.

    They missed the cliff didn't they? So much for hitting a 15mx15m target!

    Cheers

    Steve
     
  7. bobbysocks

    bobbysocks Well-Known Member

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    #7 bobbysocks, Dec 31, 2012
    Last edited: Dec 31, 2012
  8. fubar57

    fubar57 Well-Known Member

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    This the photo you were talking about Gary?

    gary.JPG

    Geo
     
  9. stona

    stona Well-Known Member

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    #9 stona, Jan 1, 2013
    Last edited: Jan 1, 2013
    The cliff was the 110m high Mons-Klint on the Danish island of Mon,120Km North West of Peenemunde.On the first attempt the Mistel combination was climbing towards the Southern point of the island of Rugen when it all went horribly wrong. Holzbaur lost control of the combination and carried out an emergency seperation. The Ju 88 slammed into the ground 3km from the village of Thiessow on Rugen island. There was,predictably,a huge explosion followed by a 900m high mushroom cloud.Every window in Thiessow was broken. There was a cover up,even including a mock funeral at a cemetary near Karlshagen at which the crew of the "bomber" were "buried".
    A second test was carried out on 25th May 1944. This time all went well until the seperated Ju 88 neared the cliff at which point it "....made a vertical descent,but missed the target by a wide margin." According to the report submitted by the OKL the Ju 88 overshot by 40m and had a 100m lateral error.
    It seems to have been good enough to convince the RLM that the weapon was viable.

    The first anti-shipping operation was carried out on 24th June 1944. Most of the Ju 88s crashed into the sea but one flew straight at HMS Nith exploding very close to her,so close that the wing of the Ju 88 cut her seaboat in half. HMS Nith was severely damaged and there were nine dead and twenty seven wounded amongst her crew. Tragic for HMS Nith and her company,but a major battleship she was not. HMS Nith was a River Class Frigate. She acted as the headquarters ship for the 231st Infantry Brigade which had landed near Arromanches on D-Day. When hit she was lying off Gold Beach carrying out her secondary task of controlling shipping during the Anglo/Canadian build up at Courseulles-sur-Mer.

    Cheers

    Steve
     
  10. Njaco

    Njaco The Pop-Tart Whisperer
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    That does look like a ETC 501 rack underneath...

    Mistel  _Fw 190F-8 _ Ju 88G-1_ - captured May __45.jpg junkerju88mistelbf109gc.jpg
     
  11. Geedee

    Geedee Well-Known Member

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    Crickey....thats what I love about you guys...ask a question (no matter how bizzare you might think it be !) and sure enough, it gets answered straight back !!

    What you've listed is brilliant and has answered my questions with far more details than I was hoping for.

    Quite simply outstanding work chaps :thumbright:

    Yup, thats the one. And looking at it in a larger format, shows a lot more detail. Many thanks for adding that one...and errrrrr, what is it underneath ?, is it a long range tank ?
     
  12. stona

    stona Well-Known Member

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    I think that there is some kind of experimental auxiliary fuel tank slung underneath the Fw 190 in that Mistel 2 combination.
    It might even stay with the Ju88 on seperation but it's hard to see and I'm guessing :)
    Cheers
    Steve
     
  13. fubar57

    fubar57 Well-Known Member

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    Gary, the book says that this was a "long range combination" so as Steve says, probably a fuel tank.

    Geo
     
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