1/18 scale Schweizer S-300C / Breda Nardi Hughes NH-300C scratchbuild model

[Nick_Karatzides]

1/18 scale Schweizer S-300C / Breda Nardi Hughes NH-300C scratchbuild model

The Hughes TH-55 Osage was a piston powered light training helicopter produced for the United States Army. It was also produced as the Model 269 family of light utility helicopters, some of which were marketed as the Model 300. The Model 300C was produced and further developed by Schweizer Aircraft Corporation as S-300 after 1983. The Hughes 300 has been also built under license by:

• Kawasaki Jukogyo KK in Japan, for delivery to the Nihon Rikujyo Jieitai (Japanese Ground Self Defence Force) and given the Japanese military serials 61301 to 61338 at Akeno, Kasumigaura, and Iwanuma.
  
• Breda Nardi in Italy, for delivery to the Aeroporia Stratou (Hellenic Army Aviation) and given the Greek military serials ES-111 to ES-130

In both countries, the parts were initially imported from the United States with full scale production following later. Now, manufactured by Schweizer Aircraft Corporation, a recent subsidiary of Sikorsky Aircraft, the basic design has been in production for almost 50 years. The three bladed main rotor and piston powered Schweizer S-300 is mostly used as a cost effective platform for training and agriculture.

The helicopter was created with a fully articulated clockwise rotating (as seen from the cockpit), three bladed main rotor and a two bladed tail rotor that would remain as distinctive characteristics of all its variants. It also has shock absorber dampened, skid type landing gear. The flight controls are directly linked to the control surfaces of the helicopter so there are no hydraulic systems. There are generally two sets of controls, although this was optional on the civil version.

Frakie steps out of his private helicopter. The glass with Scotch in hand doesn't surprise me. What really strikes me is that he does not hold a lit Cuban in his other hand.

The Schweizer S-300C / Breda Nardi Hughes NH-300C helicopter has flown under Greek flag markings, with two users:

Schweizer S-300C with Olympic Aviation - subsidiary of Olympic Airlines

Olympic Airlines (now Olympic Air) was the flag carrier airline of Greece, operated services to domestic & world-wide destinations. It was formed by invested by Greek shipping-magnate Aristotle Onassis, back in 1957 as Olympic Airways and the company developed rapidly. Under Aristotle Onassis' leadership, the airline gained a reputation for lavish style. The cabin crews were attired in Pierre Cardin designed uniforms and passengers ate with golden cutlery and listened to the stylings of a pianist in the first class cabin. On 22 January 1973, an incident occurred that dramatically changed the future of OA. The death of Aristotle Onassis' son, Alexander, in a plane crash came as a shock to the Greek people and a new phase began for Olympic Airways. A few months later, Aristotle Onassis sold all of the OA shares to the Greek State and died shortly after in 1975. By December 2003, the Olympic Airways Group of Companies owned Olympic Airways, Olympic Aviation, Macedonian Airlines, Galileo Hellas, Olympic Fuel Company, Olympic Into Plane Company and Olympic Catering restructured by the Greek State and renamed as Olympic Airlines SA. On March 2009, the Greek State announced they had reached an agreement to sell the flight operations, ground handling operations and technical base of the group to MIG - Marfin Investment Group, the largest Greek investment fund, thus ending a 35-year period of state ownership. On September 2009 Olympic Airlines ceased all operations and most flights and Olympic Air, the new airline formed from its privatization, commenced flights.

Sketch diagrams by Nick Karatzides

Schweizer S-300C registered as SX-HNB with Olympic Aviation markings as seen at Eleftherios Venizelos LGAV airport on February 6, 2008. This specific helicopter had an emergency landing on mount Parnitha on 22/4/2008. Photograph by Alex Filippopoulos.

Breda Nardi Hughes NH-300C with Hellenic Army School of Aviation

The Hellenic Army School of Aviation, based at Stefanovikio AB, Greece, operates 20 Breda Nardi Hughes NH-300C (actually Italian made S-300 built by Breda Nardi under Schweizer Aircraft Corporation licence) helicopters for the initial rotary aviation training, received in 1985, replacing in this role the old Bell OH-13/47G Sioux helicopters. The total flight training lasts 44 weeks and the training conducted by Breda Nardi Hughes NH-300C helicopter, lasts 15 weeks. Each student completes 30 flight hours behind the NH-300C controls before proceed to the next level. Each student pilot works with his own flight instructor. Every flight hour is conducted in the presence of the flight instructor seated as co-pilot while the helicopter is operated by the student pilot. Today, after almost 27 years in Greek service and about 35000 hours of training conducted in this type of helicopter, the ratio of accidents to personnel is zero, proving the reliability of the helicopter, despite the large strain susceptible because of nature of training.

Sketch diagrams by Nick Karatzides

Breda Nardi Hughes NH-300C registered as ES-111 with Hellenic Army Aviation markings as seen at Stefanovikio AB located at LGSV airport on September 16 2008. Photograph by Chris Lofting.

According to Textron Lycoming engine manual legend:

• "AE" means "Aerobatic Engine",
  
• "H" means "Helicopter",
  
• "I" means "fuel Injected",
  
• "L" means "Left hand rotation crankshaft",
  
• "O" means "Opposed cylinders",
  
• "T" means "Turbocharged".

The Hellenic Army's Breda Nardi Hughes NH-300C helicopter is powered by a 190 shp / 142 kW Textron Lycoming HIO-360-D1A 4cylinder, horizontally opposed engine compared to HIO-360-B1A, 180 hp / 134 kW of the basic version and had a larger diameter main rotor 26 ft 10 in (8.178 m) compared to 25 ft 4 in (7.6 m) of the basic version. Larger rotor and engine gives a 45% performance increase over previous models. Flight operation under IFR - Instrument Flight Rules is prohibited. Flight operation is permitted at night only when landing, navigation, instrument and anticollision lights are operative. Flight operation at night is limited to VFR - Visual Flight Rules conditions. The technical data & general characteristics as described into official flight manual are:

• Type designation: Breda Nardi Hughes NH-300C,
  
• Usage: Basic training helicopter,
  
• Crew: 1 student pilot & 1 instructor pilot,
  
• Year of construction: 1985,
  
• Manufacturer: Breda Nardi Italy under Schweizer Aircraft Corporation licence,
  
• Country: Italy,
  
• Length: 30 ft 8 in (9.34 m),
  
• Height: 8 ft 9 in (2.75 m),
  
• Width: 6 ft (1.83 m.),
  
• Main rotor diameter: 26 ft 10 in (8.178 m),
  
• Main rotor blade area: 22.64 ft² (2.103 m²),
  
• Main rotor geometric disc area: 565.49 ft² (52.534 m²),
  
• Main rotor geometric solidity ratio: 0.04,
  
• Main rotor blade chord: 6.75 in (171.5 mm),
  
• Main rotor blade twist: -8° 39',
  
• Main rotor number of blades: 3,
  
• Tail rotor blade area: 1.69 ft² (0.157 m²),
  
• Tail rotor geometric disc area: 14.19 ft² (1.318 m²),
  
• Tail rotor geometric effective solidity ratio: 0.116,
  
• Tail rotor blade collective pitch full left pedal: +25° to +27°,
  
• Tail rotor blade collective pitch full right pedal: -11° to -13°,
  
• Horizontial stabilizer area (to tail boom): 2.65 ft² (0.246 m²),
  
• Vertical stabilizer area (to tail boom): 1 ft² (0.093 m²),
  
• Empty weight: 1040 lb (470 kg),
  
• Loaded weight: 1000 lb (450 kg),
  
• Maximum takeoff weight: 2050 lb (930 kg),
  
• Powerplant: 1 x Textron Lycoming HIO-360-D1A 4cylinder, horizontally opposed engine rated at 142 kW,
  
• Horse power: 190 shp at 2700 rpm,
  
• RPM limits: 442 to 471 rpm (power on), 390 to 504 rpm (power off),
  
• Maximum hover altitude with ground effect: 5900 ft (1800 m),
  
• Maximum hover altitude without ground effect: 2750 ft (840 m),
  
• Maximum takeoff / landing operating altitude: 8000 ft,
  
• Maximum enroute operating altitude: 10200 ft (3110 m),
  
• Maximum speed at sea level with doors not installed: 91 kts (169 km/h),
  
• Maximum speed at sea level with doors installed: 115 kts (212 km/h),
  
• Maximum speed at 10000 ft with doors installed: 82.5 kts (153 km/h),
  
• Cruise speed: 75 kts (140 km/h),
  
• Rate of climb: 750 ft/min (229 m/min),
  
• Maximum autonomy range: 195 nm (360 km),
  
• Maximum flight duration: 3 hours 30 minutes depending on flight conditions & type of mission,
  
• Maximum range fuel consumption: 10.2 gallons,
  
• Fuel tank capacity: 29.6 US gallons,
  
• Collective stick (full down to full up): 10 in (254 mm),
  
• Cyclic control stick (full forward to full aft): 15 in (381 mm),
  
• Cyclic control stick (full left to full right): 16 in (406 mm),
  
• Directional control pedals (full forward to full aft): 8 in (203 mm),
  
• Throttle grip twist angle (full closed to full open): 130°.

The truth is that until this moment, I have not decided yet if I'm about to build the civilian Olympic Aviation version or the military related Hellenic Army Aviation version, Although these two versions (Schweizer S-300C and Breda Nardi Hughes NH-300C) do not differ too much, there are some elements that set them aside - especially in the cockpit area. General speaking, I don't really feel like a military model enthusiast or to be more precise, after all these dozens of F-16s, F-4s & Mirages I have built since I was a young boy, I need to deal with something less militarized. However, I must admit that the dirt, dust and rust suits best on military scale models.

In short, I'm into a dilemma and do not know which version to proceed, since both Olympic Aviation & Hellenic Army Aviation, looks nice! Ideas & suggestions are very welcome.

[Nick_Karatzides]

CHAPTER I - Building process planning

This helicopter has a special significance for me - it is one of my favourites. To be honest, I always wanted to build it under scale, since I was a kid and had seen it for the first time during an elementary school visit to Hellenic Army Aviation AB. As far as I know, it is available as a scale model kit by Special Hobby into 1/72 scale and Profiline into 1/48 scale, but didn't manage to find a large (eg 1/32) scale kit sold in the hobby shops. That means scratchbuild party time, using styrene plastic sheet, epoxy putty, basswood and my best of luck.

Building from scratch, is actually (from my POV) the essence of scale modeling, because it offers the satisfaction to build a unique, one-of-a-kind model. Unfortunately, scratchbuilding may also bring up unpleasant surprises if the scale modeler does not previously provide efficient references and have planned a comprehensive working methodology by which to proceed all construction stages. For this reason and to ensure that I will successfully manage to handle any difficulties that might arise, I preplanned every construction stage, scheduled a time period to achive my goals and determine in advance which parts will be built earlier and which later to finally set assembled as a realistic looking scale model.

• Bubble shaped cabin & clear canopy construction,
  
• Instrument panel & cockpit components construction,
  
• Undercarriage skids & shock absorbers construction,
  
• Main internal framework & components construction,
  
• Engine & pwr transmission components construction,
  
• Tail boom airframe and tail rotor blades construction,
  
• Fuel tank canister and supporting plate construction,
  
• Main rotor blades & transmission shaft construction,
  
• Clear canopy installation on the bubble shaped cabin,
  
• Individual built parts primer coat and paint applying,
  
• Decals, wash and weather effects applying on paint,
  
• Individual built and paint parts final test & assemble,
  
• Airfield tarmac diorama display base construction.

[komoras]

Nick, it is a great idea and a challenge to build this beautiful bird. Knowing your other work, I'll watch this with enjoyment and try to learn some new things by the way. Both civil and military versions look very hot, but as you said, rust and wash looks way better on a military machine, and that is why my voice goes to the orange one. Carry on! 

[Nick_Karatzides]

• Schweizer S-300C Olympic Aviation / WHITE paint,
  
• Breda Nardi NH-300C Hellenic Army / ORANGE paint.

Decision finally made. Let's go Army (beat Navy?), let's build the militarized ORANGE paint version!

[Nick_Karatzides]

CHAPTER II - Bubble shaped cabin & clear canopy construction

The Breda Nardi Hughes NH-300C trainer helicopter is equipped with a 4.25 ft (1.30 m) wide crew cabin and a tinted bubble shaped canopy providing a perfect 360° wide visibility for the instructor and student pilot. In some cases (as observed in many helicopters of this type), the tinted canopy is so dark that look like black. Side doors installation is optional.

To produce a thin-skinned, right-to-scale bubble shaped cabin, a solid rock one piece master cast of the cabin should be made of modeling clay or polyester filler or basswood first and then try to reproduce a copy by vacuum forming. The aim is to produce the bubble shaped cabin as a single moulding cast in styrene plastic sheet and clear polycarbonate for the glass canopy and the side doors. Fellow scale modelers that may have already read my previously WIP article, describing the 1/18 scale Bölkow Bö-102 Helitrainer scratchbuild project building, might remember that I've already present in detail the method to produce a bubble shaped canopy by vacuum forming styrene plastic and polycarbonate clear sheet. Additionally, into another article describing the 1/18 scale Jukka Tervamäki Engineering JT-9T autogyro project building, I also explain in a very detailed manner, how to build a home made vacuum forming device, starting from scratch and using materials that can be found in your local super market. If you are not aware how to scratchbuild a vacuum former, please feel free to read it as described and it might be useful for your future scale modelling projects.

[Nick_Karatzides]

I had already bought a package of air dry modelling clay and I was about to start the bubble cabin's core building process, while the following sequence of coincidence events took place. While visiting a good friend (scale modeller also) at his home and discussing about our WIP projects, he told me that he found a piece of toy (?) that looked a lot like to what I wanted to build. I did not pay much attention because he said that he found it into a toy store, while looking for a present to buy for his kid and I thought that a piece of toy could never be useful for my building project. In addition, since he is a strictly WWII AFV scale modeller with no special knowledge on rotary aviation related stuff, I thought that he might sees all the helicopters like the same. Despite I had no hope finding something worthwhile, I visited this toy store next day and OMG I found the following item, as previously described by my friend. This little yellow shiny thing immediately caught my attention. As I was informed by the toy shop owner, it was an add-on product for outdoors radio controlled helicopters - a field that I am completely unaware.

So far, I had the impression that the vast majority of the RC modelers, do not really care about scale accuracy and appearance on their models. I had the impression that they only wanted to set this little thing up to the air, without taking special care on scale accuracy, realistic panel washing, weather effects applying with pigments etc. That's why I had absolutely no idea if this RC related item was actually scale accurate - in any scale. Since I had no ruler or any 1/18 scale converted & printed paper material on that moment, I could only estimate "by sight" if it could be useful for my running project. The low price (approx 20€) persuaded me to buy it, knowing that it was most possible to never use it and send it directly to garbage bin. After all, the 20€ amount loss and a temporary frustration would be the worst case scenario if this item would be useless for the purpose I need it. On other words, risk management from theory to practice and applications for scale modelling.

Coming back home and heading to my hobby room bench, I rolled out the 1/18 scale converted & printed on A3 sized paper page material I keep and compare it with the newly acquired Kyosho add-on product, by placing next one to the other.

Voila! Isn't that just amazing? Even though the scale modelling Gods were conspiring to help me find exactly what I was looking for, precisely sized on the accurate scale that I needed it, at the most opportune moment, it would never be so successfully achieved as actually happened just by pure luck. Considering the situation as happened, the following conclusions can be drawn:

• I'm defiantly lucky as Gastone Duck,
  
• My "by sight" size estimations are deadly accurate,
  
• I did not expect from an AFV scale modeler to accurately recognize the helicopter, remember it and suggest it as a problem solution when I told him about my attempts to scratch build it. I do confess that I was impressed and I've change my mind for AFV scale modelers for whom I had always believed they are considered unrelated to aircrafts & helicopters scale models.

[Nick_Karatzides]

The truth is that I like building from scratch, but if I find something ready built & precisely sized on the accurate scale that I need it, I keep it - anybody would. It's stupid to build something from scratch, when it's already available to buy on the market. Obviously, the newly acquired Kyosho add-on cabin product for RC models, is not what someone might call as a highly detailed piece of art or a best choice ever. The reason I decided to stick with it, is because it looks like a nice platform for wide modifications and scratch detailing, until finally look like a realistic and accurate on 1/18 scale Breda Nardi Hughes NH-300C model. There were three things I did upon deciding to keep the Kyosho add-on cabin product and use it for extensive modifications & model building purposes:

• The tinted bubble shaped canopy made of polycarbonate, was removed from cabin and placed into a plastic bag to keep it safe until time to work with it,
  
• The twin fuel tank canisters sawed off and removed from canopy since they are not accurate to scale and will be built from scratch later,
  
• Despite the fact that the cabin and the tinted bubble shaped canopy dimensions are strictly accurate in 1/18 scale, the cabin's lower chin fairing looks much shorter than it should - on the basis of the printed material & 3view diagrams. Feel free to check following picture and notice the difference between the present lower chin fairing (marked with green colour) under the cabin and the right to scale lower chin fairing (marked with red colour stripes). Obviously, the present lower chin fairing is shorter than it should be and it will be built from scratch.

While planning the building, I thought as nice idea to build the helicopter model without the lower chin fairing and let the inner detail shown as appear in the following picture. As the construction progress was underway, I changed my mind because I discovered that the helicopter would loose its aerodynamic appearance and look more like a wreck than an operative flying machine.

Schweizer S-300C registered as C-FIBC with Silverline Helicopters, hanging around on a hoist so its overhauled landing gear can be reattached. Photograph by Chris Coates, shot at Holland Landing CLA4 on June 24 2006.

The cabin's lower chin fairing should be constructed as one piece section. To produce a thin-skinned, right-to-scale cabin's lower chin fairing, a solid rock one piece master cast of the cabin's lower chin fairing should be made of modeling clay or polyester filler or basswood first and then try to reproduce a copy by vacuum forming. The aim is to produce the cabin's lower chin fairing as a single moulding cast in styrene plastic sheet.

[Nick_Karatzides]

My first thought was to build the solid rock one piece master cast of the cabin's lower chin fairing, by standard Milliput yellow grey epoxy putty or polyester filler as I usually do. Since I had recently purchased a new material, I thought it would be a good opportunity to try it. Experimenting new stuff (mostly unconventional to the known techniques) and finding possible applications on scale modeling, was always fascinating for me.

Water based acrylic putty used to seal wall imperfections, indoors home improvement and other decorative applications, which becomes like hardened plaster when it dries, seemed just the right for the job. The stuff has excellent working properties, dries fast without cracking, is easy to sand and gives a smooth surface. Under normal conditions, it is touch dry after 30 minutes and can be safely sanded after 2 or 3 hours. So, I opened an 800 gr canister bought for 2€ only, pick a small quantity, add as required and start building the cabin's lower chin fairing master cast shape by hand, following closely the dimensions of the 1/18 scale converted & printed on A3 sized paper page material found into the helicopter's official technical order manual.

As soon as the basic core made of standard Milliput yellow grey epoxy putty, had enough time to get hardened, I start covering with water based acrylic putty layers one after the other. The material felt too soft and very easy to spread nicely, offering plenty of time to try forming and detailing.

I left it overnight and as soon as the lower chin fairing's master cast made of water based acrylic putty had enough time to get hardened, it was sanded carefully to get the ideal curved shape. Additional details made with styrene plastic rods on the master cast which was finally sprayed with a gloss coat to help me spot any scratches or defect marks. Following the same method as described in previous WIP articles, the lower chin fairing produced in styrene plastic, by vacuum forming the hand made master cast. I always buy large styrene plastic 50x30cm sheets for 0.5€ to 1.5€ each (depending width), not the more expensive styrene by Evergreen. When an attempt fails, I usually throw the sheet back in the oven and start again. Once you have the machine, you can make all kinds of things. You can make a lot of aircraft wings, airframe parts, opened panels etc out of a styrene plastic sheet like that. You can build the master cast from basswood, epoxy, polyester etc and the parts you produce depend on how accurate the master cast is. The master cast must be as accurate and detailed as necessary to achieve the results you are after.

[Nick_Karatzides]

I got few wooden picture frames found at the local IKEA store for only 1€ to 3€ each (depending size) and few thumbtacks, to use them for steady & tight styrene sheet holding while being heated. Because I was planning to use smaller wooden frame to secure the styrene plastic sheet (the piece to be vacuum formed is not big and there is no need to spend styrene plastic card), I had to close the outer holes on the vacuum former's hardboard high-density fibreboard plate. To do so, I cut a plastic bag in shape and covered as required the desired area.

I pinned a styrene plastic sheet on the wooden frame and insert it into the preheated electric oven to some predetermined level, whatever works and start heating the styrene plastic sheet. I have never tried this with a gas one, so use caution if you do!

[Nick_Karatzides]

As soon as I noticed that it started drooping down, I removed the frame while wearing Nomex Aramid flame resistant MilSpec gloves, to prevent finger burns. While the vacuum cleaner was already switched on, I placed the wooden frame with the pined styrene plastic sheet on the vacuum former plate. The styrene plastic nicely formed around the master cast... and voila!

Using a sharp new #11 surgical blade, I removed the vacuum formed cabin's lower chin fairing piece from the styrene plastic sheet and tried some test fitting on the cabin. As seen in the following pictures, the cabin's lower chin fairing build succeeded in first attempt. It was important to make sure that it would not foul the main build.

Well, it seems that this specific water based acrylic putty passed exams and became a part of my tools. I will certainly use it again when first opportunity may arise because:

• Can be poured into any desired shape,
  
• Becomes touch dry after 30 minutes and can be safely sanded after 2 or 3 hours, offering plenty of time to shape the master cast and add details as required,
  
• Does not crack as long manufacturer's instructions are followed,
  
• Can be sanded, drilled, sawed etc,
  
• Additional layers can be added on previously build ups,
  
• Can be purchased at your local crafts store or any decent hardware store into 800ml or bigger canisters,
  
• It is cheaper than dirt! Estimated prices are 2€ to 5€ depending the canister size.

Finally, even if you do not use it for scale modelling purposes, do some home improvement and repair the garage wall for which your wife complains for so long.

[modellius]

superb work mate !