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"Fuhrungsmaschine"

by Sam Garcia

 

Mistel "Fuhrungsmaschine"

 


B a c k g r o u n d 

 

Misteln were composite aircraft originally conceived to attack large or fortified enemy targets using specially modified "war weary" Ju-88 aircraft as unguided air-to-ground weapons. Early Misteln were constructed by replacing the cockpit section of Ju-88 -A (Mistel 1) or -G (Mistel 2) series aircraft with a large shaped-charge warhead. Mistel pilot training was done in Schulmistel aircraft (designated with an "S" e.g. Mistel S1) where the Ju-88 cockpit section was left intact. Navigation to target was done by a piloted Me-109F (Mistel 1) or Fw-190A (Mistel 2) rigidly mounted atop the Ju-88 "bomb" via special struts. At the target, the guidance aircraft would set up the "bomb run" visually and release the weapon, allowing it to fly along its trajectory, strike and destroy its intended target. At least that was how it was supposed to work. In reality, Misteln were largely ineffective due to several weaknesses, including the absence of in-flight guidance; and interception of the very slow composite aircraft by Allied fighters.

As Germany’s situation continued to degrade in the final phase of the war, it was faced with rapidly encroaching Allied ground and air forces from both the East and West. The Luftwaffe found itself with an inability of asserting even temporary, highly localized air superiority. Although its operations were almost exclusively confined to interception of allied bomber streams (Reichverteidigung) and enemy armour concentrations (Schlactflieger), Luftwaffe bureaucrats attempted to maintain an "offensive tactical" capability. Unfortunately, such "offensive" assets would be forced to operate from bases deep within the German heartland. As a result, the range required to strike fixed enemy targets increased and imposed the simultaneous burdens of longer range and increased probability of interception on all Luftwaffe aircraft.

Within this environment the Mistel composite aircraft concept was utilized to yield a project known as the Fuhrungsmaschine. The design, which never progressed beyond the Projekt stage, consisted of an Fw-190A-8 mounted atop a Ju-88H-4 equipped with a nose-mounted, surface search centimetric radar system. Unlike the Misteln, however, the mission of this composite aircraft was "ultra-long" range pathfinder duties. In this design, the Ju-88H-4 served as "mother ship" while the parasitic Fw-190A-8 was intended to serve as detachable fighter escort.

 

 

Although never actually built, the Ju-88H-4 was development of the Ju-88H-2 originally designed as a long range Zerstorer. Major differences between the H-4 and its H-2 predescessor were: replacement of the H-2’s BMW 801 radial powerplants by inline JuMos, a substantial extension of the fuselage to accommodate fuel storage for the parasitic fighter and a redesigned nose section housing centimetric surface search radar. Additionally, the Ju-88H-4 was outfitted with FuG 220 and radar altimeters.

The parasitic Fw-190A-8 component as such was never actually built. Although several configurations of Doppelreiter fuel tanks were tried on a few early Fw-190A Versuchs aircraft, they were never adopted. On this hypothetical Fw 190A-8 aircraft, the outboard wing cannon (MG 151 20mm or Mk 108 30mm) were removed.

 

C o n s t r u c t i o n

 

Construction is fairly straightforward per kit and conversion instructions. As the H-4 fuselage build is the most complicated section, it’s highlighted in some detail below. If not specifically highlighted, the construction is per kit instruction.

DML’s Mistel 2/S-2 (kit 5510) was modified by incorporating the following:

  • Paragon Design’s "Fuhrungsmaschine" resin conversion set #48-047
  • High Flight’s Ju-88 flap set #4836
  • Kendall Model Company’s Fw-190 flight control surfaces set #48-5017
  • Eduard’s photoetched Fw-190A flap set #48-011

 

To finish the project as described below, you will need to get hold of the following:

  • Two Jumo 213 nacelles, corresponding spinners and props (fortunately "spared" in several of DML’s Ju-88G kits)
  • Two 900 l fuel tanks (ours came from Fujimi’s Bf 110C/D),
  • A second ETC hardpoint for the Ju-88H-4 (ours came from a DML Ju-88G-6). (part C1)
  • Depending upon preferences, you may want to use a vac-form canopy

 

Construction began with the Ju-88H-4. The cockpit was built up per kit instructions. The cockpit radar station supplied in the Paragon set was installed per instructions. After spraying with Humbrol Schwarzgrau 66, instrument faces and dials were painted black and drybrushed lightly with medium grey. Hoses and belts were painted the appropriate colors. Finally, the cockpit and sidewalls were washed with thinned black artist oils and drybrushed with RLM 02 or aluminum as appropriate.

Fuselage parts A1 and A2 were carefully separated along the panel line immediately aft of the wing trailing edge as indicated in Paragon’s instructions. This results in two sections, A1/A2 "forward" and "aft". After cleanup of the various plastic and resin mating surfaces, all six of the fuselage components were dry fit. Several minor problems surfaced here, the most significant being the aft-most resin section was slightly smaller in cross section than the injection molded fuselage. More on that later.

 

 

Satisfied with what lay ahead, the wing root was carefully cut out from kit parts C17 and C18. Keep in mind the resulting holes are filled from the backside by resin patches from the Paragon kit, so don’t overdo it when removing the roots. Dry fit, dress, mate the resin patches to kit parts C17 and C18, fill and sand. When complete, the sidewalls and cockpit were inserted into parts C17 and C18 as appropriate, then C17 was mated to C18 and the seams dressed as necessary. At this point, the resin nose was attached. With this section, you will need to extensively fill the nose seam with CA and build up the rear canopy-to-fuselage join with plastic card and CA. These fills require lots of CA so be prepared to use low grit paper/tapes and lots of elbow grease! You will need to rescribe nearly all the panel lines here, so take some notes BEFORE you sand!

Mate parts A1 "forward" to A2 "forward" and then A1 "aft" to A2 "aft". Now comes a little engineering fun!

Because the aircraft will be "handled" extensively, the resin/plastic joints between the two aftmost sections required reinforcement, specifically: A1/A2 "forward" to aft resin plug and aft resin plug to A1/A2 "aft". To do this, four ~5" sections of 1/8" plastic rod were inserted through the middle of the hollow aft resin fuselage section. One rod was placed in each corner of the interior of the hollow resin plug. The rod was centered along the corner until equal lengths extended fore and aft of the resin plug section. This leaves ~0.5" extending fore and aft from the resin plug. The rods were epoxied into place. Slide a ~0.75" length of 1/8" ID plastic tube over the forward end of each rod. These are sleeves which will mount inside A1/A2 "forward". Before you can get there, however, you’ll need to buildup inside A1/A2 "forward" (and later "aft) because the walls of the resin section are much thicker than the plastic. Do this with multiple dry fits. Not to worry anyone, if you don’t intend to extensively handle the model, this extensive reinforcement is not required!

Once the buildup of the seats for the sleeves is complete, carefully place a drop of epoxy or CA on the external portion of the sleeve, to get it to "stick" to the seat in the injection molded fuselage subassembly. If using CA, use 15-25 second cure as some "adjustment" may be necessary when bringing the A1/A2 "forward" and resin plug subassemblies together. After waiting the prescribed time, gently pull the resin section back, you should see each of the four sleeves have pulled off the rods and are now tacked in the proper orientation on their seats in the A1/A2 "forward" subassembly. At this point, you can add more reinforcement or more CA/epoxy to firmly fix the sleeves.

The process just described is repeated for the aft seam joining the aft resin plug and A1/A2 "aft". When complete, approximately 30g of lead shot was placed inside the fuselage near the tail wheel as an insurance against having the center of gravity move too far forward and, also, to increase the stability of the resting model. At this point epoxy or CA the rods into the sleeves. While it sounds complicated, with just a little patience, it will provide a strong seam that will withstand sustained unintentional abuse. You are now down to just two pieces left to finish the fuselage. Voila! You’ve just become an honorary structural engineer!

Finish the fuselage subassembly by mating the nose/C17/C18 subassembly to the forward resin plug. This seam does not require any reinforcement. When dry, mate this subassembly to the recently finished "A1/A2 forward:aft resin plug:A1/A2 aft" subassembly.

At this point you are holding a really long fuselage in your hand! You will note there may be a 1/32" step between the "A1/A2 forward" and "aft resin plug" seam. Remove a little plastic from trailing edge of the A1/A2 "forward" section with a file or motor tool and then build up the leading edge of the aft resin plug with a little CA. Apply your favorite putty. With a little more work from your motor tool or a flat metal file, you are ready to dress the seam using finer and finer grits with your Flex-I-File and all is well with the world.

At this point, fine sand the entire fuselage, rescribe any lost surface detail and primer the seams to scout for any subtle imperfections. In this case Humbrol light grey was used.

After a little light sanding and touchup on the primered seams, the vertical and horizontal stabilizers, rudder and elevator assemblies were added. A nice kit feature is that you can offset them from neutral if desired.

Don’t forget to locate and drill a hole to accept the "jettisonable" third main landing gear leg.

Now on to the wings! The flaps were removed from the wing section and replaced with the High Flight resin set. Because of the way the High Flight flaps fit into the Ju-88H-4 wing, no blinding was required. Don’t forget to open the strut locating holes before closing the wings! Remember to swapout the BMW 801 engines and replace them with Ju 213s. This is not a problem but a touch of putty was required. Nacelles, spinners and propellers from the Ju-88G-6 kit were used. Antennae mounts were added at the indicated positions under the wings.

Dry-fit the wing/fuselage join, attach them and the Ju-88H-4’s ready for paint!

 

 

Now for the Fw-190! It was decided to replace the DML Fw-190A-8 with a Tamiya Fw-190F-8. The kit flaps, rudder and elevators were removed. Strut receptor holes were drilled out, the wings mated and seams dressed. The resulting "wells" in the wing created by removing the flaps were blinded off with plastic card before an Eduard PE flap set was installed. This area, when dry would be sprayed with RLM 02. Kendall Model Company’s flight control surfaces were used. The rudder and elevators were offset from neutral. Fine Molds PE belts were added to the cockpit. Exhaust shrouds absent in the Tamiya kit were scratchbuilt.

 

 

The Doppelreiter tanks were dry fit. It was found that the starboard tank appeared about 1/16" shorter than the port tank. After plastic stock was added, shaped and feathered, the "fixed" overwing tanks were installed.

The ETC rack was left off because the Doppelreiter tanks eliminated the need for a belly tank and the fighter escort role was inconsistent with a need to carry ground-attack ordnance. Along with the outboard wing cannon, the ETC rack might possibly have been removed to save weight. Who knows? Have fun!

 

P a i n t i n g   a n d   F i n i s h i n g

 

Unless noted otherwise, custom-blended Tamiya acrylics and Aeromaster decals were used throughout.

First, let’s do the Ju-88H-4. Make sure you have dipped the kit canopy in Future and allowed it to dry for at least 24 hours. After weighing the benefit of using a thin vac-formed canopy from Squadron, vs the better fit and sharper panel lines obtained with the kit canopy, it was decided to stick with the kit canopy. Bare Metal Foil was used to mask the canopy. Attach the canopy to the fuselage using your favorite method. Spray the canopy interior color, Schwarzgrau 66, over the canopy framing first. This way, it’s visible through the "glass".

Humbrol Graublau 76 was sprayed over the dressed and primered seams. When dry, the entire aircraft was sprayed with a second light coat of Humbrol Graublau 76. When it was dry, the aircraft was very lightly sanded with 600 grit, cleaned and finally sprayed with Tamiya Graublau 76 and allowed to cure for 24 hours. Humbrol is an excellent hard base coat for acrylics. The Humbrol primer treatment can be avoided if the model is not extensively handled.

Over this was sprayed a "loose" splotch pattern of Grauviolett 75. It is reasonable to adopt this camouflage scheme as Ju-88H-2s had this finish from the factory. These aircraft had the additional requirement for concealment on the ground. Check your references and then wind up doing what you think looks the best! In this case a dense squiggle pattern of Dunkelgrun 83 was used. For this to work visually, the squiggles were tightly bound and ~1/16" wide. Although some references have suggested squiggles were applied in several different colors, a single color scheme was maintained.

Since this aircraft was never manufactured, there was latitude for decal options. The Werknummer was selected from a block of late Ju-88Gs. After the project was already complete (of course!) I came across Werknummer information for Ju-88H-2s. Geschwader assignment (i.e. selection of fuselage codes) provided the same latitude. Conceivably one could have selected an operational unit known to have flown Misteln such as KG200 or KG30. That would have been fine but it wasn’t known that this pathfinder was intended solely to support Mistel operations. A more obscure unit, KGr 806 was selected for no good reason other than to be different. In retrospect, one might also have considered using one of the Fernaufklarungsgruppen which were operating Ju-88s/188s. In any event, modelling should be fun, so have fun!

The aircraft was given a light wash with thinned artist’s oils. Very light exhaust staining was added. Finally, upper wing and nacelle panel line detail was further highlighted using a black ink pen.

In order to simulate the "newness" of the Ju-88H-4 aircraft, it was oversprayed with clear satin to simulate the "sheen" fresh Luftwaffe paints were reported to have (at least with the 74/75/76 schemes). This would later contrast nicely with the severely weathered battle worn Fw-190A steed charged with its defense!

 

 

Many references agree that the mating of the Fw-190 and Ju-88G aircraft in Misteln was done on a "whatever was available" basis. Consequently, the fuselage codes and camouflage patterns of the two aircraft were not matched. In fact, it was decided to exploit this to add artistic richness to the project by combining the two "textures" which the aircraft were chosen to represent.

The Fw-190 was painted overall in a standard Graugrun 74/Grauviolette 75/Graublau 76 scheme. In order to enhance the wear and tear impression, the paints were mixed to a much lighter shade. It was reasoned that the installation of the overwing tanks would be a Rustsatze modification, and as such the tonal quality of the wing and over wing tanks paints would not match. Hence, the Doppelreiter tanks were resprayed this time using "factory fresh" color. Yellow cowl and underwing markings were added as indicated. Additional "ground concealment" was supplied for this fighter with a few stripes of Braunviolette 81 added along the rear fuselage spine and continuing down the sides. This paint was blended to a "not quite factory fresh" standard.

The aircraft was sealed with a gloss coat in preparation for the Aeromaster decals. When the base coat was dry, the decals were applied using the Microscale system and allowed to dry overnight. A light overcoat of acrylic flat was applied at this point. Once dry, the aircraft was given a heavy wash with thinned black artist oils. Extremely heavy exhaust staining was added using Tamiya’s smoke and artist’s oils. The aircraft was left alone for 24 hours. Upper surfaces were lightly drybrushed with white to add "wear and tear" and to bring out surface detail. Some weathering was done using a brush and silver/grey mix around the cockpit and port wing root area. Voila! You have one interesting looking aircraft! Finally, several overcoats of acrylic clear flat were added and the paint left to dry overnight.

 

C o n c l u s i o n

 

This was a very different aircraft and a very different project. The project depicts a hypothetical aircraft which was never actually built. This had good and bad points associated with it. The latitude the project provided for painting and decaling was refreshing. At the same time, wanting to be reasonably "realistic" or perhaps "probabilistic" was challenging because of the lack of a lot of reference material. The project allowed further expression in the combination of the "old and the new". For me it reinforced the overall impression of what deplorable conditions existed in the Luftwaffe at war’s end.

It was fun!

 

R e f e r e n c e s

 

Mistel, Composite Aircraft of the Luftwaffe, Schiffer

Ju-88 in Action, Squadron/Signal

AeroDetail #20 Ju-88, Model Graphix

Warplanes of the Third Reich, William Green

 


Model, Article Text and Photographs Copyright 1998 by Sam Garcia
Page Created 31 December, 1998
Last Updated 26 July, 2007

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