1/35 scale Rheinmetall Mk 20 RH-202 2x20mm Hellenic Army

[Nick_Karatzides]

1/35 scale Rheinmetall Mk 20 RH-202 2x20mm Hellenic Army
towed anti aircraft system model by Hecker & Goros

It's been long time since the mid 1990ies, I had the opportunity as a young officer in Hellenic Army, to receive an invitation to watch the tactical evaluation of NATO AA gunners at NAMFI - NATO Missile Firing Instalations in Suda bay / Crete island. The  German Army AA gunners, launched Roland II SAM missiles based on Marder IFVs and the Hellenic Army AA gunners engaged aerial RC targets with the Rheinmetall Mk 20 RH-202 2x20mm cannons. In the following picture, me as a Hellenic Army 2nd Lieutenant, between the German Army Captain / Hauptmann who was in charge with the German Army's Rolland II SAMs on Marder IFVs AA Battery at that time and the German Army Sergeant Major / Oberstabsfeldwebel who was the technical maintenance master chief. The date is 15 years before today.

Lucky me, I managed to shot few pictures and keep in mind few things for (future) scale modelling projects too. Since this article is about the Rheinmetall Mk 20 RH-202 2x20mm scale model, have a look on few pictures of that day.

Few years later, during my summer vacations on an Aegean island, I walked around and examined the Rheinmetall Mk 20 RH-202 system details, while visiting a forwarded AA post, based on the island. According to the crew, the AA post was 24/7 operational, the ammo belts were stored next to the system, to provide a 5 minutes readiness, which is enough time for the crew to load the ammo belts and prepare the RH for operation.

As the successor model to the 20mm HS-820 cannon, the Government of the Federal Republic of Germany was planning a development, the Rheinmetall offered under its own name RH-202. This AA system should be not only much cheaper than the 20mm HS-820, but also much better: with maximum of fire readiness, extended operational life, resistance against weather, dirt, sand & water and ease operation and field maintenance. The Rheinmetall Zwillingsflak twin gun anti aircraft system, designed to match the mission of the low level air defence units of the German Air Force, to engage low and very low approaching enemy aircraft with all appropriate means in time to prevent them from firing their weapons or delivering their ordnance or at least to prevent them from carrying out an accurate attack on an Air Force installation. The Budget Committee of the Bundestag approved the Zwillingsflak system in December 1969 and serial production began few months later. Volume production in Düsseldorf and in the second manufacturing site at Mauser in Oberndorf began in May 1970. Initial problems in production were solved quickly, and the RH-202 was promoted in the service of the Bundeswehr into a Rheinmetall success story: In 1967 the Federal Ministry of Defence accepted the automatic cannon for the introduction in all branches of service. Through the consistent use of the 20mm RH-202 at Army, Air Force and Navy is thus guaranteed in the Federal Republic of Germany for a limited time, the weapons & ammunition standardization. The first serially manufactured systems reached units of the Bundeswehr on October 12th 1972. Rheinmetall delivered the last of these systems in 1976. It was used by the Argentine Air Force (FAA - Fuerza Aérea Argentina) during the Falklands War, used in the defense of the airfield at Port Stanley Falkland.. Since 1981, it is used by the Portuguese Army (Exército Português) and the Portuguese Air Force (FAP - Força Aérea Portuguesa). The Rheinmetall Mk 20 RH-202 2x20mm AA system is withdrawn from service with the German Armed Forces, but still in active use with the Hellenic Army AA artillery, the HAF - Hellenic Air Force, the Turkish Armed Forces and Indonesian Army air defence as well. A total of 6630 Rheinmetall Mk 20 RH-202 systems were produced.

The Rheinmetall Mk 20 RH-202 20x139mm AA system can be transferred after placed on two-wheeled trailer. It and can be coupled to a light vehicle such as the Mercedes Benz 240GD Geländewagen , or a military truck such as the Mercedes Benz Unimog or the Steyr 680M - all of them are in service in the Hellenic Army & the Hellenic Air Force.

In firing position the installation is supported by three pillars. The gunner is sitting back, handles the system with a joystick and aims the gun on the target using the Italian made Officine Galileo R-56 computerized sight, which has an optical viewfinder with an x5 increase, serial connected with an electronic analog firing computer to calculate lead angles, distances and point of impact for firing against aerial or ground targets, the arm control mechanisms, vertical & traverse, a placard to display information the data etc. Mechanisms of -5.5° to +85° vertical & 360° traverse are operated hydraulically with a maximum speed of rotation of 80 degrees / sec and vertical guidance of 48 degrees / sec. System is completely autonomous, equipt with an on-board two-stroke gasoline Wankel typed air cooled engine (established under the gunner's seat), providing needed electric power to operate the hydraulic servos, the Officine Galileo R-56 computerized sight, the on-board firing computer and the electronic controls. Although, under emergency situations (or if no electric power) it can also be manually operated using handles, but firing computer data cannot be transferred to the optical sight if system is not electric powered.

It is a precision anti aircraft system with a high rate of fire, ideal to allow high accuracy engagement against aerial targets that cannot be reached with rifles or machine guns. The two 20mm cannons are fully automatic, gas operated with floating mounted base, thus reducing the recoil forces and achieving maximum accuracy, reliability and service life. The gunner is shooting, by pressing the pedal fitted with a fuse with left foot, setting accurate fire into 2000m effective range, until 7000m maximum range. Single barrel or dual automatic shooting can be selected through the control panel, with 2000 rounds / min, per barrel - that means that the Rheinmetall Mk 20 RH-202 AA system, fires with a 4000 rounds / min rate, when both barrels operation is selected by the gunner. The belt feeders are gas-operated and belt transport is independent of cannon and bolt recoil. A number of 280 rounds of 20x139mm ammunition are stored in each side ammo box - total 560 rounds on the system, ready to fire. A flexible hose connecting the ammo box with a gun, is feeding with rounds all time. Using a variety of 20x139mm ammo, including BS with a detachable tray, BZTS, FZS, FZTS and various training with projectile weight 134g (0.3 lb) full caliber or 108g APDS can provide muzzle velocity 1150 m/s (3770 ft/s) - deadly effective against low flying targets.

Two versions of the Rheinmetall Mk 20 RH-202 AA system received by the Hellenic Army under special order to cover the anti aircraft Artillery demands. The main visible difference between these two versions is the iron sight or the telescopic sight (used for pre-aiming) placed over the main Officine Galileo R-56 computerized sight eyescope. These two versions differ (apart from the obvious visible difference as explained before) a few more external details on the electronic control switches. Both versions can also be electronically connected with the S-11 simulator (see following picture), used for AA gunners daily exercise.

[Nick_Karatzides]

CHAPTER I - Soft metal kit preparation & cleaning

To be honest, since I've already had a first taste of 1/35 scale, I was actually planning to build both the German Army's Rolland II SAMs on Marder IFV, to remember that day at NAMFI. But, just because I didn't find available Marder IFV scale model with Rolland II SAM yet, I thought as best idea to start with the 1/35 scale Rheinmetall Mk 20 RH-202 2x20mm AA system model kit by Hecker & Goros (already found into a London UK hobby shop) first and continue with the Rolland II SAM on Marder IFV model as a future project. As far as I tried Google, I didn't find any additional Rheinmetall kits available, so I consider myself as lucky I found it.

The assembly instructions contained in the kit is actually an A4 size sheet, one side only printed guide describes the building steps.

The soft metal pieces were carefully placed into sealed transparent bags. Unfortunately, after careful inspection to spot any possible defects, cracks, gaps, etc. I found one piece missing, but no problem as long as I could replace it scratchbuild with plastic styrene sheet. Additionally, the soft metal pieces simulating the barrels, found in quite bad condition in box, 30° warped and I was afraid that giving them back a nice 'n' straight line shape, could result a crack. Luckily, straightening the warped barrels was an easy job, but I also had a plan-B option to buy RBM Models 1/35 scale accessory suitable for Marder's 1A2 Rheinmetall cannon barrel if something didn't go as expected. Additionally, using the minitool, I carefully opened realistic flash suppressers because I was disappointed with the original ones.

Since the Hellenic Army's 230 pages manual for operation & technical maintenance is not quite suitable for scale modeling use, I preferred the official Rheinmetall's 500 pages technical maintenance manual which is the best reference I could get before starting the project. Before starting the building, I placed the metal pieces side by side and compared them with the diagrams and detailed pictures found into the Rheinmetall's technical maintenance manual.

[Nick_Karatzides]

CHAPTER II - Main model building & detailing

Following the simple assembly instructions, I placed each metal piece on place using two-component cyanoacrylate glue for best results. The model parts are molded in such way that no putty is needed to fill any gaps - just clean the soft metal parts from cast line and glue it on desired spot. The kit is very easy to assemble and actual on scale with enough details to make it look realistic. Using styrene plastic sheet, and having the official diagrams and detailed pictures found into Rheinmetall's technical maintenance manual, I added few more details. Checking the parts carefully, I found that few items (such as the front shield) were more thickness that they should. Sanding with nail file, was just OK to make it look more realistic. The fuel tank hatch release handle, have been detailed according the diagrams and pictures and glued it in "CLOSED" position.

The following pictures indicate some of the detail improvements added, using the Rheinmetall's technical maintenance manual & few of my pictures as reference guide.

As soon as all the details, hatch covers, handles, etc were fit & glued on the scale model, I spray a primer light layer over the model to prepare for painting process and highlight any deficiencies that had escaped my attention so far.

[Nick_Karatzides]

CHAPTER III - Gunner figure building & detailing

Hecker & Goros provides a soft metal figure representing a German Army's Rheinmetall Mk 20 RH-202 AA system gunner. The point is, that the figure is offered as one piece with the adjustable seat. That would be a problem for me, because I was planning a no-figure set. You see, figure building & painting is not my field. But, as long as I was not in a mood to spend few hours to build a decent seat from scratch, I decide to include the figure in the project. After all, since I tried building non-aviation related stuff, I could also try myself converting and painting a scale figure too.

As you can see at the previous pictures I took at the NAMFI, the Rheinmetall Mk 20 RH-202 AA system gunners did not wear a steel or Kevlar helmet while firing live ammo. That could be against the military rules, but when they need to be concentrated on aerial target and open fire with a 4000 rounds / min rate, they should not worry for such details. For this reason, I cut the German Army gunner's head and replaced it with his grand father's head, from an old Tamiya set. The new cap covered head were trimmed, sanded to look realistic and got a new Hellenic Army pin on the upper front. The metal arms also had to be changed because it was nearly impossible to place the gunner's hands on the control joystick in realistic way. Plastic arms found into my spare box, fit in place with cyanoacrylate glue and the final result were sprayed with primer to prepare for painting process and highlight any deficiencies that had escaped my attention so far.

[Aki]

Very nice my friend, excellent work!



Best regards,

Aleksa

[Nick_Karatzides]

CHAPTER IV - Applying paint, wash & weather effects

The first Rheinmetall Mk 20 RH-202 towed AA systems, received by Hellenic Army AA artillery battalions and HAF squadrons, entered active duty on early '80ies. Until 1995, more than 800 systems were in Greek service. They were painted with the CARC - Chemical Agent Resistant Coating which is specially formulated to reduce the system's IR image reflection. From CARC paint manufacturer's brochure (page #5) found in HERE it is clear that "...MilSpray CARC touchup, creates no IR image...".

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Also, in page #2 you can read: "...Key to survivability in combat is avoidance of enemy detection systems and IR homing weapons. CARC coated vehicles and equipment have signature-reduction properties that diminish the effectiveness of existing and emerging enemy detection and targeting systems. While infrared reflectivity is one element of signature-reduction, other characteristics and their particulars are considered classified information. Infrared Signature (IR) management is one of the least understood, yet most important attributes of the CARC camouflage system. Each of the colors in the camouflage system contains a special pigment package that camouflages vehicles and equipment when they are in their intended theater of operation. As an example, the 383 green color in the camouflage pattern, has an IR signature equal, or less than, that of chlorophyll. When viewed in IR, the vehicle will blend in with the wooded environment and will not create an IR signature that could be used by enemy weapons systems having IR homing technology. IR homing weapons systems can be found in MANPADs and many shoulder fired missiles...".

When received by the Hellenic Armed Forces and until today, these towed anti aircraft systems did not have any national markings. Also, keep in mind, that I no Rheinmetall ever seen with the bronze plaque in honor of St. Barbara (which in the manners, customs and traditions of the Hellenic Army protects the Artillery), was installed yet! What I'll try to display, is a Rheinmetall Mk 20 RH-202 AA system scale model as they appeared in Hellenic Army AA artillery service during the late 1990ies / early 2000ies period. Notice the "nose art" style details found on some of the Rheinmetall front plate shields.

The scale model carefully washed with liquid soap and warm water to disappear leaving oil traces, fingertips etc. Some fellow scale modelers might prefer to use alcohol to remove leaving oil traces, fingertips etc, but I wouldn't recommend it, because the alcohol tends to remove or shrink the majority of modelling filler putty products. As long as the model was already light grey primed, I sprayed black paint preshading lines across the lines & around the details. The exact colour the Rheinmetall Mk 20 RH-202 towed AA systems are painted, is quite difficult to define. According to the official Rheinmetall painting guide, it is the FS34086 which looks OK to me, but I found few pictures where the colour tends to seem more brown than green, actually - I think this is so, due to different lighting conditions during picture shooting or old & faded photographs.

Here's something to compare the official FS34086 "Army Forest Green Camo" to FS34087 "Olive Drab" which is more likely in the previous pictures.

I believe that the basic CARC FS34086 "Army Forest Green Camo" colour is quite close to the Humbrol's #66 "Matt Olive Drab" or Gunze Sangyo's #78.

Because I had in mind to present lighter tones on model's surface, to simulate the scale effect, I tried the official FS34086 "Army Forest Green Camo" which is available by Life Color as UA106 "Aermacchi Green Verde " acrylic paint, enlighted with right percentage of white colour as the SLC - Scale Lighting effect Calculator program estimates. Using the SLC - Scale Lighting effect Calculator program, I placed as basic colour the FS34086 (RGB code 58x60x47) and set the parameters such as 1/35 scale, appearance of model's surface in a scale from a "new - just painted" level to "old - paints are fade" level, according to what I had in mind to create, etc. and the program, draw the results. For example:

• RGB code 71x73x61 as the suggested 7% scale lighting paint for a "NEW - just painted" model,
  
• RGB code 81x82x71 as the suggested 13% scale lighting paint for a "MEDium weathered" model,
  
• RGB code 89x91x80 as the suggested 19% scale lighting paint for an "OLD - paints are fade" model.

I asked for "NEW - just painted" data, considering that the Rheinmetall Mk 20 RH-202 towed AA systems are well treated, usually covered with tarpaulins when not in use and never spoiled with mud, dirt etc so the paint doesn't look faded or extreme weathered, despite being in active service for several years. Offcourse, some high lighted details, will be enlighted, using lighter OD tones.

The Life Color's official FS34086 / UA106 "Aermacchi Green Verde " acrylic paint, enlighted with 7% matt white & sand mixture. The first base very diluted acrylic colour was sprayed with no problem as a light layer and let dry overnight.

[Nick_Karatzides]

As soon as the previous very diluted Life Color acrylic paint layer dried, a second (very diluted also) layer sprayed over, so the final result will become dark enough, that can be considered as into a realistic tonality & lighting colour range, while the black preshading lines, are still visible under the applied colour layers. Minor corrections were made in 1-2 spots with a fine brush. After the acrylic paint got dried, I had to add selectively some dirt & dust effects.

[Nick_Karatzides]

CHAPTER V - Display concrete base & gravel

I found nice idea to place it on a display base, simulating the concrete covered launching area as I actually saw it at NAMFI. From my local store, I bought a 20x30cm polished wooden picture frame.

I add some grams of plaster powder and few drops of water with a syringe into a soft rubber cup to make the right mixture. Materials like plaster, start as a dry powder that is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after drying and this characteristic make plaster suitable for the job. Keep in mind that adding salt into wet plaster mixture, reduce the plaster's hardening time and adding vinegar into wet plaster mixture, extend the plaster's hardening time. When the first layer of thinned plaster applied on the picture frame, a glass were pushed against the plaster to form a flat basic strong cast.

I left it few hours to get harden in order to be sure that the cast wouldn't break when I would try to cut it into desired shape. Meanwhile, I took the soft rubber cup which I used to make the plaster mixture, squized it to break the last hardened plaster left inside, so it would be easier for me to clean it afterwards and prepare it for any future mix. That's the reason this soft rubber cup were used for.

Before the plaster cast got harden, I formed the field area into the desired shape to be suitable for the Rheinmetall Mk 20 RH-202 AA system scale model. I thought as nice idea to add few grams of sprinkled sea sand in order to simulate the gravel covered ground, around the concrete base. Water based white glue for wood, which becomes transparent when it dries, is just the right for the job. So, I opened a 500 grams canister bought for 2€ only, pick a small quantity, add just few drops of water with a syringe into a small metal container to make the right mixture and finally I applied on the desired areas to be covered with sea sand. Because the mixture is enriched with water based glue, it is easy to correct possible mistakes.

Finally, the Rheinmetall Mk 20 RH-202 AA system scale model glued on the base with silicon. Here are some test pictures. Please keep in kind that this is not final, as some details such as the 20x139mm ammo shells will be added at last, the gunners figure is not placed yet and some minor details will be placed later.

[Nick_Karatzides]

Details such as the 20x139mm ammo shells and the red flag indicating that the Rheinmetall Mk 20 RH-202 AA system is loaded with live ammo, were added at last. After being paint black and washed with brown dark rust tones, the ammo shells set in place using white glue. You can compare the size of the real 20x139mm ammo with the 1/35 scale brass.

[Nick_Karatzides]

CHAPTER VI - Epilogue

Using the home inject printer, I created a "MEHMET BUISTERS" water transfer decal to place on the front right shield, as seen on a real Rheinmetall Mk 20 RH-202 AA system and presented few paragraphs before with THIS picture. The decal printed as expected and was accurate on scale, but unfortunately, the picture was not just right – I didn't liked it and as soon as I took the picture, the water transfer decal, removed. After all, I am trying to represent a Rheinmetall Mk 20 RH-202 AA system, as seen at NAMFI and the "MEHMET BUSTERS" one, was seen in another location.

As final, I took some pictures with the final vignette side by side with the 1/18 scale model which I've already started, currently scratchbuilding and hoping to finish soon. A Life Color paint and a dummy round are also posing as a size reference for the WIP 1/18 scale model. Thank you for following this thread and I hope you enjoyed reading this article and I hope you like the following pictures:

Regards,
Nick