Engineering the Colonial Viper

Where do you start with the engineering design of the Viper?

My inspirations are firmly based on the fighter warbirds of WW2 – the Spitfire, Corsair, Mustang, etc.  I’m aiming to engineer the Viper in a similar manner to these World War 2 fighters, using aluminium airframe construction techniques.

Spitfire cutaway drawing

Spitfire cutaway drawing

 

Spitfire fuselage bulkeads/frames

Spitfire fuselage bulkeads/frames

Spitfire fuselage construction

Spitfire fuselage construction

Spitfire rear fuselage construction detail

Spitfire rear fuselage construction detail

Spitfire fuselage with skin

Spitfire fuselage with skin

Many years ago I completed a mechanical engineering diploma, which covered subjects like engineering drawing,
materials, processes and workshop training.  I thought I’d purged most of that knowledge, but it’s amazing
how much of it I had retained.  It was to prove invaluable during the initial design stages of the project.
I initially sketched a schematic cutaway, detailing the internal bulkheads/formers.

Colonial Viper cutaway view sketch

Colonial Viper cutaway view sketch

Design started with a search for any available plans on the internet, particularly, the fuselage profile
(formers/frames/bulkheads).  The original prop designs were available, although I couldn’t find any of
suitable quality – at least not enough for me to loft (expand in size) into full scale plans.

Original Colonial Viper blueprints

Original Colonial Viper blueprints

Viper fuselage bulkhead profiles from the original blueprints

Viper fuselage bulkhead profiles from the original blueprints

The most difficult sections to engineer would be the front section of the fuselage with it’s many curved profiles
and the three engine intakes.  The other components, like the circular engines, wings, fin and rear of
the fuselage are relatively simple, geometrically speaking.

The original Monogram/Revell plastic model kit is not a bad reference but is known to have a few inaccuracies.
The more recent Moebius kit is a lot closer in accuracy to the original filming models and full size prop.  At
1/32 scale, I decided the Moebius model would be a great guide for the overall dimensions.  Armed with a pair of
digital vernier calipers, I measured the dimensions of the model and scaled them up to full size 1:1.

I would use a combination of the accurized plastic model kits and the original prop designs to develop
my own fuselage profile designs.  These were initially drawn onto graph paper and lofted to full scale
drawings.  These drawings were then plotted onto signboard and cut out for use as templates, to verify the
fuselage alignment and to allow plywood form blocks to be made.

Viper profile sketches

Viper profile sketches

 

Plotted Viper profiles for lofting to 1:1 scale

Plotted Viper profiles for lofting to 1:1 scale

I decided to concentrate on the nose intake and first 1/3 of the fuselage.  I developed a full scale half fuselage mockup to check the accuracy of the formers, the stringer locations and the appearance of the overall profile.

Viper fuselage nose section profile

Viper fuselage nose section profile

IMG_0842

IMG_0857

IMG_0846

IMG_0848

Next time I’ll be detailing the construction of the nose and intake using sheet aluminium formed using plywood form blocks.  Stay tuned…

 

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