When the Standard Aircraft Corporation opened its doors in 1916, there were very few tradespeople with a significant background in aviation manufacturing. This was entirely understandable, as the first licensed aircraft manufacturer in the United States, The Burgess Company and Curtis Incorporated, had only been building aircraft in a production capacity since 1911. The capabilities of aircraft would increase by leaps and bounds in just three years. Within the first few months of World War I, aircraft proved themselves to be a viable weapon on the battlefield. By 1916 there was tremendous demand for an alarmingly small supply of domestic aircraft designers and skilled fabricators.
Fortunately, the answer to this serious shortcoming came in the form or America’s shipwrights, furniture makers, musical instrument makers, and coach builders. These skilled tradespeople could call upon generations of experience fabricating wooden vehicles and structures to a high degree of precision and quality. They had access to a tremendous variety of highly specialized tools and a demonstrated proficiency in mass production. Standard Aircraft Corporation took advantage of this when they contracted with Fisher Body Corporation, a renowned coach builder in Detroit. Wood workers and fabricators of the early 20th century had the luxury of motorized tools to perform some of the more taxing operations relating to the conversion of rough timber into usable dimensional stock. However, for much of the finer joinery and surfacing, a craftsman would still rely on traditional hand tools, and that will the subject of this blog.
I was lucky enough to come upon a veritable treasure trove of fine woodworking tools in a storage cabinet in the Preservation and Restoration Unit’s wood shop labeled “Paul Garber Tools.” (Garber was a key player in the establishment of our museum, amassing an incredible collection of historic aircraft for the Smithsonian in the mid-20th century.) These tools showed some signs of long-term storage, i.e. rust, but were to become perfectly functional following a thorough application of elbow grease and some fine tuning. The first tool I restored was a Stanley Number 5 hand plane. It was such a popular tool that it was in, more-or-less, constant production from 1869 to 1984. It is often called a “Jack” plane or a “Fore” plane because most woodworkers have deemed it the Jack of all trades hand plane and the one you use “(be)fore” any other. It very much lives up to its name — and it has helped me with the Museum’s restoration of our Lincoln Standard H.S. (Modified Standard J-1).
I had to construct a new horizontal stabilizer for the Standard J-1 as the original was too severely damaged to risk reinstalling on an aircraft to be displayed above the heads of museum guests. The Number 5 hand plane was exactly what I needed to mill a new Sitka Spruce spar for the horizontal stabilizer. No piece of lumber, no matter how high quality, will be dead straight when it comes from a sawmill. There will always be some degree of twist, bow, and curve. The hand plane’s long, flat metal sole allows the blade to only remove wood from the high spots on a piece of lumber. By doing so, the hand plane can be used to sequentially flatten each face of a piece of wood, thus removing the twist, bow, and curve.
After using the hand plane to create a dead straight piece of timber for the spar, I then drew centerlines and bevels onto the lumber to match what was called out on the blueprints. The spar tapers slightly fore and aft as well as at each end. Once all lines were drawn, I simply had to remove any material outside of the lines. It is immensely satisfying to operate a well-tuned hand plane. The wood shavings make an audible “swish” as they curl out from the mouth of the tool and the sweet aroma of spruce resin follows soon after. A sharp blade will leave a glass-smooth surface behind that does not require any additional sanding. Another benefit of using a hand plane over a power planer or jointer is that the depth of cut can be tuned so finely that it is easy to remove a shaving of wood thin enough to read through. This allows one to sneak up to the line and fabricate a precise aircraft component.
The wings of the National Air and Space Museum’s Standard J-1 also required extensive repair. They are constructed with a Sitka Spruce leading edge, ribs composed of a basswood lower cap strip, web (middle section with an airfoil profile) and upper cap strip, two Sitka Spruce spars, and a Sitka Spruce trailing edge. The rounded wingtips and wing roots are constructed of laminated Poplar. I had to fabricate multiple rip cap strips, rib webs, and trailing edges for the four wing panels. The rib webs have an under cambered airfoil profile meaning they have a convex curve on their upper surface and a concave curve on their lower surface. I was able to use a powered band saw to rough out the desired profile but to get a precise shape with the smoothest possible gluing surface, I had to revert to the Stanley Victor Model 20 Compass Plane. This tool was manufactured in the 1890s and excels at shaping curved surfaces. The base of the plane is made from spring steel and a threaded post allows the base to be pushed or pulled into a convex or concave shape. There really is no better tool for the task of shaping smooth arcs. I can adjust the sole to perfectly match the radius called out on the blueprints. Just like the Stanley Number 5, I can set the blade to take a fine cut so that I may gradually sneak up to the line. I also had to repair the four laminated and steam-bent wingtips. These wingtips have a compound bend, meaning that they curve in two axes. Damaged portions of the wingtips were cut out and new ones were installed using multiple glued scarf joints. I had to make the new wingtip components slightly oversize to allow for any size discrepancy in each of the four wingtips. The Model 20 Compass Plane was the perfect tool for the final shaping and blending of the compound curves on the wingtips.
When the radius of a curved component was too tight for the compass plane, I would use a spoke shave. The spoke shave takes its name from its original purpose, the shaping of round spokes for wagon wheels. It functions much like a hand plane, with the added flexibility that it can be either pushed or pulled against the wood. In their earliest iterations, automobiles still used wooden wheels, as wood was surprisingly strong for its weight and had the ability to reduce the force of road vibration. A variety of spoke shaves with flat, curved, or rounded soles could be found in nearly every coach builder’s tool chest. I used spoke shaves with flat and rounded soles to shape the lightening holes cut into the rib webs and the tight bends of the wing roots. While this could have been accomplished with a power spindle sander. the resulting curves would never be quite fair and would exhibit ragged edges, as the wood fibers are torn, rather than sliced. An additional benefit of the spoke shave is that it is eminently portable and I can use it in nearly any direction and position.
The cap strips that are nailed and glued to the upper and lower edges of the wing rib webs turn each wing rib into a miniature I beam. They must fit tightly to the rib webs at a precise 90-degree angle. In order to accomplish this, a narrow slot must be milled into the underside of each cap strip. The rough work can be done with a powered router but the resultant slot, called a dado, is often uneven and full of fuzzy wood fibers. To fine tune the width of the dado and leave a crisp, smooth surface, I used the Stanley Model 98 Side Rabbet Plane. It is a small tool with a single purpose. Honed to a keen edge, the blade of the 98 allowed me to mill the sides of the dado so precisely that the cap strip adhered to the rib web with friction alone. I do not know of any modern power tool that can do this as successfully.
Multiple joints on the Standard J-1 have a stepped profile, often called a rabbet. A rabbet must be dead flat with a crisp 90-degree angle at the shoulder. The rudder bar mounts in the front and rear cockpits are attached to Sitka Spruce floors composed of five shaped pieces. They are assembled using a shiplap joint which is essentially formed of two vertically opposed rabbets. The joint takes its name from a watertight type of construction used on bulkheads in wooden ships. I was able to rough out the joints using the table saw but was again left with a slightly irregular and fuzzy surface. There is always some degree of vibration in a spinning table saw blade as it enters and leaves the wood. To perfectly fit each shiplap joint, I utilized the Stanley Model Number 93 Cabinet Makers' Rabbet Plane. It is designed to cut perfectly square inside corners with a blade that cuts right up to the edge of the side, or shoulder, of the plane. With the ability to remove gossamer-thin shavings of wood, I was able to fit the shiplap joints tight enough to make the glue line essentially disappear.
Assembly line mass production was in full swing in the United States by the second decade of the 20th century. Power tools driven by alternating current or compressed air were becoming the norm. Trees were processed into usable structural timber more efficiently than ever before. Amongst all of this industrial might, one could be led to believe that a hand tool designed in the 18th or 19th century had no place in aviation. I can personally attest that they play a critical role. They are quiet, safe, never run out of power, exhibit excellent ergonomics, and, in skilled hands, permit a degree of control and precision not available with power tools. They are especially useful in a restoration and preservation capacity when building a “one-off” is so common and it is impractical to set up dedicated jigs and machinery. I am fortunate to have access to the collection of tools from Paul Garber and delight in using century old tools to restore a century old aircraft.
Author: Jay Flanagan, Museum Specialist (Aeronautics), Collections Department