In 1980, just before hanging up the models to concentrate on making a living (and burnout), I started a design project on the Spitfire 24. It was to be as scale-like as possible, molded from carbon, retract gear and convection cooled by scale radiators. Molds were made for the wing and horizontal stabilizer. A female mold was made of the wing leading edge and some parts of the wing actually fabricated. It was intended, at the time, to be another World Championship "go for broke" effort.
Like many semi-scale modelers, part of the fun is researching your chosen aircraft, and imagining it as a stunt ship. My research included a trip to the RAF Museum, while on a London layover, where I shot a roll of photos of Spitfire 24 details. I also purchased a Spitfire 24 Pilots Notes, and a copy of every illustration in the Spitfire 24 maintenance manual. This is in addition, of course, to books, pamphlets and magazine excerpts collected over the years. In fact, I have probably have more information on the Spitfire than I do on Mustangs, and that's saying a bunch.
The fuselage, wing and tail surface designs started with three views projected from several sources, including a photograph, and copied, in different color inks to indicate their source. The wing, fuselage and tail surfaces were copied to different scales as necessitated by the demands of stunt moments but the outlines were maintained, as close as possible, to scale.
When designing a semi-scale airplane, it isn't enough to use accurate outlines of the components. The various components have to be "blended" and "harmonized" so that individual units don't seem out of place or overpowering. At the time, I would have started building this airplane, reserving changes to the final configuration, until I could begin to see the airplane in three dimensions. With the fuselage sitting on the wing, the tail moment would have been decided on and cardboard cutouts of the tail surfaces pinned in place to visualize the final effect. With basic moments and areas in mind, they are "massaged" to obtain a specific, calculated, tail volume.
Now, I make foam board, half scale models, to visualize various configurations before beginning construction. The effects of various moments and areas are taken into consideration of the requirements of competition stunt. The initial wing layout of the Critical Mass was rejected after seeing it on the foam board model. The Reno racer clipped wing looked "stubby" and ugly. This caused me to opt for the more elegant Sea Fury wing with its higher aspect ratio wing without "clipping". I found out that "clipped wing" semi-scale Reno racers and competition stunt are mutually exclusive. This process has helped to avoid several serious errors and the scraping of visually awkward and unsatisfactory components.
[photo not recovered: 436b98f3091e97f5.jpg]
This first drawing is the many outlined first approximation to my design, drawn to the projected size of the model. There are four different outlines from three views, and one from a photograph, in this drawing. The projected wing location is also shown in this drawing, in blue. There is also a stab location, but it is harder to make out. The first step in the design was to settle on the final outline and enlarge the vertical fin and rudder. Enlarging the vertical fin and rudder is necessary to give a proper appearance when positioned next to the oversize stab and elevators. Fortunately, the Spitfire 24 already had a very large vertical fin and rudder identical to its Supermarine stable mate, the Spiteful. This minimized the need to enlarge the vertical tail surfaces and allowed closer to scale Spitfire/Spiteful outlines.
[photo not recovered: 436b99190972a4a3.jpg]
This second drawing is also taken from three views, sized for stunt. This drawing forms the basis for a stunt wing having a realistic Spitfire outline. The stab is also an enlarged three view resized to stunt requirements.
[photo not recovered: 436b99940df98e93.jpg]
This was my first working drawing of this semi-scale Spitfire 24. Spitfire 24s were often referred to as the "Ultimate Spitfire" and that was what I was going to call mine.
[photo not recovered: 436b99b80e213950.jpg]
This is my Spitfire 24 wing male mold. First, it is sized to stunt requirements with a 62" span and a 10" root chord, not counting the flaps. It featured my latest airfoils and scale details which wouldn't have interfered with stunt performance, like gun blisters and blisters over the gear hinges and tires. This wing has a flat center section, like the real Spitfire, and two dihedral breaks, one on each side of the fuselage. Ultimately, I had hoped to refine the molds to produce color gel-coated parts with surface details so common today. It would have made a very interesting semi-scale wing.
Now, the effort is history, and these artifacts remain as part of my collection of plans, magazines, three views, books, photos, wall hanging airplanes and broken parts. It reminds me of what might have been, what I did, and the fun I had doing it. Now I have new designs, new airplanes, articles, and videos. Retirement allows more free time to build and fly stunt.
Al
Like many semi-scale modelers, part of the fun is researching your chosen aircraft, and imagining it as a stunt ship. My research included a trip to the RAF Museum, while on a London layover, where I shot a roll of photos of Spitfire 24 details. I also purchased a Spitfire 24 Pilots Notes, and a copy of every illustration in the Spitfire 24 maintenance manual. This is in addition, of course, to books, pamphlets and magazine excerpts collected over the years. In fact, I have probably have more information on the Spitfire than I do on Mustangs, and that's saying a bunch.
The fuselage, wing and tail surface designs started with three views projected from several sources, including a photograph, and copied, in different color inks to indicate their source. The wing, fuselage and tail surfaces were copied to different scales as necessitated by the demands of stunt moments but the outlines were maintained, as close as possible, to scale.
When designing a semi-scale airplane, it isn't enough to use accurate outlines of the components. The various components have to be "blended" and "harmonized" so that individual units don't seem out of place or overpowering. At the time, I would have started building this airplane, reserving changes to the final configuration, until I could begin to see the airplane in three dimensions. With the fuselage sitting on the wing, the tail moment would have been decided on and cardboard cutouts of the tail surfaces pinned in place to visualize the final effect. With basic moments and areas in mind, they are "massaged" to obtain a specific, calculated, tail volume.
Now, I make foam board, half scale models, to visualize various configurations before beginning construction. The effects of various moments and areas are taken into consideration of the requirements of competition stunt. The initial wing layout of the Critical Mass was rejected after seeing it on the foam board model. The Reno racer clipped wing looked "stubby" and ugly. This caused me to opt for the more elegant Sea Fury wing with its higher aspect ratio wing without "clipping". I found out that "clipped wing" semi-scale Reno racers and competition stunt are mutually exclusive. This process has helped to avoid several serious errors and the scraping of visually awkward and unsatisfactory components.
[photo not recovered: 436b98f3091e97f5.jpg]
This first drawing is the many outlined first approximation to my design, drawn to the projected size of the model. There are four different outlines from three views, and one from a photograph, in this drawing. The projected wing location is also shown in this drawing, in blue. There is also a stab location, but it is harder to make out. The first step in the design was to settle on the final outline and enlarge the vertical fin and rudder. Enlarging the vertical fin and rudder is necessary to give a proper appearance when positioned next to the oversize stab and elevators. Fortunately, the Spitfire 24 already had a very large vertical fin and rudder identical to its Supermarine stable mate, the Spiteful. This minimized the need to enlarge the vertical tail surfaces and allowed closer to scale Spitfire/Spiteful outlines.
[photo not recovered: 436b99190972a4a3.jpg]
This second drawing is also taken from three views, sized for stunt. This drawing forms the basis for a stunt wing having a realistic Spitfire outline. The stab is also an enlarged three view resized to stunt requirements.
[photo not recovered: 436b99940df98e93.jpg]
This was my first working drawing of this semi-scale Spitfire 24. Spitfire 24s were often referred to as the "Ultimate Spitfire" and that was what I was going to call mine.
[photo not recovered: 436b99b80e213950.jpg]
This is my Spitfire 24 wing male mold. First, it is sized to stunt requirements with a 62" span and a 10" root chord, not counting the flaps. It featured my latest airfoils and scale details which wouldn't have interfered with stunt performance, like gun blisters and blisters over the gear hinges and tires. This wing has a flat center section, like the real Spitfire, and two dihedral breaks, one on each side of the fuselage. Ultimately, I had hoped to refine the molds to produce color gel-coated parts with surface details so common today. It would have made a very interesting semi-scale wing.
Now, the effort is history, and these artifacts remain as part of my collection of plans, magazines, three views, books, photos, wall hanging airplanes and broken parts. It reminds me of what might have been, what I did, and the fun I had doing it. Now I have new designs, new airplanes, articles, and videos. Retirement allows more free time to build and fly stunt.
Al
Al Rabe
