1/48 Scratchbuilt Curtiss NC4 Flying Boat

by Mike Robinson

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To say that I am a fan of flying boats is like saying an ant likes picnics. They have a grace, character and a utility that no other type of aircraft has, the ability to make 2/3’s of the world’s surface their runway. My appreciation for them was fostered in part by my Dad, a licensed pilot from the “old school” of pilots that learned to fly by the seat of their pants, and his ability for flying and landing on water.

When I first saw the story of the Curtiss NC series trip across the Atlantic in 1919, the airplanes caught my attention. Immediately I knew I wanted to build a model of one, and I knew it was going to end up being a scratchbuilt model. Even though I have scratchbuilt a few aircraft before this, this was going to be the first of this size and complexity. Gathering the reference data proved to be fairly easy. A quick email to John Bayer, Director of the First Across Organization, (http://www.geocities.com/firstacross/) resulted in several sources of plans and reference materials. Another website that gave invaluable information was The Naval Aviation History Office (http://www.history.navy.mil/branches/nc-4mono.htm). I also thought a trip to Pensacola Naval Air Museum to photograph Nancy was in order, so a quick email to the fine folks there to explain what I wanted to do resulted in a very quick response.  It said in a nutshell, “Sure come on down, we’ll be glad to help.” A trip in April of 2003 resulted in over 130 digital photos and 72 35mm Color Slides. The people there were very accommodating.  Not only did they allow me full access to Nancy, but they also rolled out a small electric scaffold to lift me up and over Nancy, allowing me to photograph the airplane from the top, as well as the bottom. I was also able to poke my head inside and get some very helpful interior pictures. I can’t recommend the Naval Air Museum enough, very nice people to deal with and a fantastic array of displays there. 

With references ready, and raw materials purchased, it was time to begin construction. I decided to begin with some of the smaller subassemblies first to get a feel if I was actually going to be able to finish this beast. The more I looked at the plans, examined the forest of struts, the maze of rigging, the more I started to think…

 “ Riiiiiiiight. I’m really going to build this… sure I am.” 

Along with that, the drawings that I obtained from Model Airplane News had some features that did not agree with the photos I had taken in a lot of areas. The Nacelles weren’t drawn quite right, some of the rigging was mis-drawn, and many details were left off the plans all together. Items like the wind driven fuel pumps on the rear deck, and the “tunnel” underneath the rear pusher engine to keep crewmembers from getting whacked by a spinning prop. Another bugaboo that would bite me good later on in construction was the fact they were drawn in two scales, 1/32nd and 1/48th. I was building the model in 1/48th scale, so it wasn’t a major issue, but there were a few times I had to get out the calculator to refigure a certain dimension.  Rather than go into a full-blown step by step construction article, I decided to give a brief outline of each subassembly, and the materials and techniques used to construct the model. That, and some In-Progress photos should give you a good idea of the amount of work and time invested. As always if you have any specific questions on how I did a certain part of the model, please feel free to email me and ask away. 

Fuselage/Hull

  • Hull master was carved from a block of basswood.
  • Hull halves vacuum-formed from .040 plastic sheet
  • Internal Hull stringers made from .010 and .005 strip.
  • Ribs and formers made from .030 sheet.
  • Cockpit floor and slat seats made from .040 plastic for frames and.010 strips for slats.
  • Instrument Panel from .010 with Reheat Gages and Foto-Cut bezels
  • Control Wheels, Rudder Bars, Throttles and Engine Controls made from brass wire and solder as needed, and spare photo etch.
  • All control cables present.
  • Interior finished to represent varnished mahogany.
  • Cockpit fairings vacuum-formed and faired in, with Compass and Windscreens made from Rod and clear sheet.
  • Hull fittings made from brass or steel wire, solder, strips of plastic as needed.
  • 4 wind driven Fuel Pumps made from Evergreen Channel and rod.
Hull begins life as paper templates pinned to the wood block and band sawed to shape, then a small block plane was used to rough carve the hull to close to final shape.

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Hull after final sanding and wing center section glued in place, and cockpit cutouts chiseled out.

Hull after vacu-forming. The basswood master was cut in half at the Cockpit Bulkhead and left in the rear portion of the hull for strength. This allowed for brass tube sockets for the lower wings to plug into. (and to prevent me from being loony enough to build a second one)

Hull interior showing slat floors, Control Bar, Rudder Pedals and Slat Seats and all control cable runs.

Wings 

  • Lower Wing Center made from .040 ribs and brass tube spar, sheeted with .010 plastic with ribs embossed from underneath. Upper Wing Center Section constructed of a 3/16 balsa core sanded to airfoil shape and sheeted with .005 plastic, ribs embossed from below.
  • Outer wing panels, both top and bottom made from 3/16 Balsa core sanded to shape, with 1/8 Rod embedded in wood at strut locations. Wings then sheeted with embossed .005 plastic, Strut locating holes and rigging holes predrilled.
  • Ailerons cut from Top Wing panels, Aerodynamic mass balances added, and then sheeted with embossed .005 plastic.
  • Struts made from Contrail Strut material, each strut cut and fitted as model sat in jig. Ends pinned with brass wire, and each strut is embedded into the plastic sockets installed in the wings. Epoxy was used to secure them.
Lower Wing structure, sans skins assembled and fitted. The assembly Jig is started.

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Clockwise from top left.  Wing skins being test fitted. Ribs embossed from underneath.  Skins are being glued in place along lead edges. Skins being cemented along outer ribs and trail edge and completed.

Hull completed, Painted, decaled and Lower Wing Center Section Completed.
Lower Outer Wings temporarily set in place and Top Wing Center section jigged into place. Balsa Cores with .005 sheeting was used for Wing construction. Small white items under left wing are wind driven Fuel Pumps.

Wing Center Section Struts cut and fitted, Tail Booms started.

Top Wing Outter Panels being test fitted

If in doubt… Jig it. One of the most gratifying features about this model is that in spite of the complexity of the construction, it all stayed in good alignment because of the care and double-checking taken during construction to ensure everything stayed straight. The jig was a bit of extra work, but the end results were worth the effort. Here the Wing Struts are all cut to length, and numbered for their particular location.

Voila! Removing the jig and nothing moved or “tweaked” out of alignment.

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Tail Surfaces

  • Both Horizontal Stabilizers and all three Rudders and Fins made from .010 plastic cores, sanded to shape, and skinned with .005 embossed plastic. All surfaces were built separate and hinged with brass wire.
  • Struts made from Contrail Strut material, cut to length and anchored with brass pins in ends.
  • Assembly was pre-assembled and painted, and rigged using Lycra thread, anchored in pre-drilled holes with CA glue.
Fin/Rudder Cores made from .010 Sheet.

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Components test fitted for fit and alignment.
Owwww my eyes! My first attempt at “Yellowed  NDL” was woefully too orange. Testor’s Lemon Yellow was deemed adequately close and Tail was repainted. Tail is complete here except for rigging.

Engine Nacelles 

  • Center Nacelle built up from Evergreen Channel, internally rigged, and engine bearers added from .060 plastic. Front Cowl and Lower Cowl Vacu-formed from .010, side panels made from .005 plastic with foot and inspection cutouts punched out. Nacelle Struts made from Contrail Struts, cut and fitted to length in a jig.
  • Wing Nacelles vacuum-formed from .040 plastic over a wooden master turned on lathe. Front cowls vacu-formed separately and added after engines were installed. Radiators resin cast from a master made from a Chevy Pickup Radiator, hoses are Solder Wire. Struts made from Contrail Strut material. A special jig was made for strut locations and lengths, and for cutting and fitting the Main Struts between all three nacelles.
  • Engines and propellers are commercial items. The Engines are Aeroclub white metal engines, with separate exhaust stacks made from solder and drilled out. Propellers are custom ordered props from Martin Digimyer and Copper State Models.

Center Nacelle framed up with Evergreen. This was then covered with Vacu-formed lower cowl and front cowl, and .005 sheet side panels. Large triangle thingy in the front is an alignment aid. Struts are Contrail Strut pinned with brass wire in the ends.

 

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Wing Nacelles vacu-formed over wood master. A scrap piece of balsa was made to the same size as the lower wing to make an assembly jig for cutting struts to length.

Nacelles after being painted, and the forest of struts cut to fit. Cradle for Assembly Jig helps hold everything in constant alignment to keep things square and even.

Engines and Radiators installed. Remember the comment on the two scales being used in the plans? This is where it bit me good. I made masters to cast the Engine Crankcases and the Cylinders. After casting 4 really nice crankcases, and 50 really nice cylinders, it was then I discovered that I made the crankcases in 1/48th scale, and the cylinders in 1/32nd scale. As Homer Simpson would say… DOH! So I said to heck with it and used the white metal Liberty’s from Aeroclub. They clean up nice and look good when painted, and the props I had custom made by Martin Digimyer, through Copper State Models.

Tail Booms 

  • The Main Booms are 1/8 inch dowel sanded to a taper on the ends. Center Fittings are aluminum tube, drilled for Cross Tree and braces. Cross Tree made from Contrail Strut Material, cut to length and pinned for strength. Center Tail Boom also made from Dowel. All were painted with Gray Lacquer and epoxied into place into holes predrilled in wings and tail.
Tail Booms being built. All were cut to length with the while model was firmly held in place in jig.

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Rigging 

  • Rigging is a combination of Lycra thread used for wing bay and control line rigging, and Nylon Monofilament used in the Tail Booms for strength. All holes pre-drilled, and CA used to anchor lines in holes.
Lycra was used for Wing Bay and Control Line rigging, Monofilament was used for the Tail Booms for strength and to hold it all in place

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Painting and Decals 

  • Hull painted with Gray Auto Acrylic Lacquer, with strips of white decal paper used to form the Numeral 4 at all 5 locations.
  • Wings and Tail painted with Model Master Insignia Yellow, fin flash painted using Insignia Red, White, and Blue, with Serial Number from scrap decals.
  • Wing National Insignia made using PC and Detail Master decal paper.
  • Struts and booms painted with Gray Auto Lacquer

Construction 

  • Nothing unusual in construction once parts were fabricated. Epoxy and CA used almost exclusively for strength and for filling seams. Wooden hull master was cut at the forward bulkhead and left inside the assembled halves for strength. A special jig was constructed to hold airframe in alignment as construction progressed, and also serves as a transport caddy.  Finished base is ½ inch particleboard, sealed and painted with the same gray used to finish model, and the pedestal is a block of mahogany. Altogether about 734 hours were put into building the model.

 

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This was a rewarding project, in that I not only had a chance to exercise some techniques I’ve used before, but I also had a chance to learn some new ones along the way, talking to other modelers and seeking their input. Is this model perfect? Heck no. I’ll be the first to admit it’s not… it has it’s share of flaws and I know there’s a few places that I had to make some “ejimicated” guesses due to lack of reference material, but over all I am very pleased with the results. It never fails to draw it’s share of ooo’s and ahhh’s wherever I take it, and it has won two awards so far, First place in Scratchbuilt Class at BUFCON 25, and First Place in Scratchbuilt Class at NOREASTCON 2004.  It’s a unique model of a unique subject, and I had a ball building it, which is after all, what modeling is supposed to be. 

I want to give a special thanks to a couple of individuals who helped with the model and the photography.  

Fellow club member Pete “Pig” Fleischman and his wonderful little vacu-form machine did a great job in pulling the hull halves.  

Another club member, Tom Johnson did the great photography work.  

Also to everyone here at ARC for following along in the “In Progress” section for their support and encouragement. It helped push me along at times when I was ready to chuck the whole thing. 

Cheers

Mike

Photos and text © by Mike Robinson