Shadow a Design Analysis

In 1982 I studied the requirements for a new category of aircraft named Microlights issued by the British CAA. Basically it was for aircraft with not more than two seats, empty weight not exceeding 150kg [331lbs], wing area at least 10kg per meter sq., load factors +4g & -2g, ultimate factor x 1.5.

Having enthused & studied all sorts of aircraft for many years I felt I was ideally qualified to have a go at my own designed aircraft. This was because having been an airframe fitter, draughtsman, design engineer & aviator. Basically an engineer who could fly.

It is quite rare for an individual to achieve the CONCEPT DESIGN CONSTRUCTION FLIGHT of an aircraft. The first to do this were the Wright Bros., another was my guiding friend Volmer Jensen [25 designs] but overall not that many. Most famous aircraft designers never built their aircraft, nor did they fly them. Fantastic aviators such as Twist, Duke, Farley, Hoover, Yeager never built or designed, they were exponents of flying skills.

Certainly from past most aircraft, in my studies, are poorly designed. They are too heavy limiting performance and efficiency. Pilots view is usually poor because designers didn't fly. overall they are dangerous due to stalls and spinning. flown by specific numbers rules apply to limit these dangers. Some things have improved - the F16 pilot view cannot be faulted but try looking forward in an F4 Phantom. The canard on the Typhoon can restrict view. Ben Rich from Lockheed once said that the only place for a canard 'is on someone else's airplane'.

Trying to correct all past mistakes is never going to be 100% but I was determined to achieve some.

Calling the aircraft Shadow it sketched out as a high wing pusher, two seat, sitting on a tricycle u/c. Everything was very carefully thought through. Pusher rear mounted engine being more efficient is also safer for persons on the ground. Glider-like canopy for the pilot. High wing mounted on a pylon above the fuselage - not just stuck on the sides. Ventral rudder because a rear mounted engine sits on it's tail when unoccupied. The second cockpit was originally conceived as a one-plus-one with limited space.

The fuselage cockpits are formed from Fiberlam honeycomb material which lent it's shape easily to comfort being reclined not even needing separate seats. Forming a one piece monocoque specialised aerospace inserts allowed hard-points anywhere. A side stick controller does not restrict allowing pilot lap free for maps etc. Electric switches forward of inadvertent operation. Fuel cut off when Off restricts throttle hand. Fuel systems from tanks automatic, no switching fuel tanks. Fuel tanks below & aft of cockpits. Crew compartments free from hazardous parts in event of a crash. Four point crew harness. Rudder pedals have levers for differential brakes for a free castoring nose wheel & a stranded wire can be tensioned by rotating the nose leg to adjust to eliminate shimmying. A real handful throttle sets the cockpit off. Many have commented that it feels similar to that of a fighter like cockpit.

My wing is a whole new way of thinking. Not having been taught anything I have my own views on flight and aerodynamics. The result has been that a Shadow has an almost imperceptible stall and cannot be made to spin. This over the last 30+ years of operation has proclaimed the Shadow series as one of the safest accident free aircraft ever built. An added accolade is that it has not had any structural deficiencies either. Ignore the CAA claiming, after 20 years, that the u/c was non-compliant and needed an expensive mod. No other Countries airworthiness thought this.

It grieves me that all students of flight still have the Bernoulli Theory of flight taught to them. An aircraft does not fly because of a reduction of lift above the wing. There is a reduction of pressure above the wing but only because of flight being caused by a downward pressure resulting in an upward force. Check the lecture by Alexander Lippish on the web saying just this. Just to unnerve sceptics note that the airflow does not flow over the wing, the wing passes through the air which is still. An aircraft will not fly unless it has an angle of attack [AoA], and that is because it needs to press the air downwards from the underside. Curved air foils only reduce drag over the upper surface.

So my wing had this drooped leading edge D section as per Irv Culver's VJ-23 hang glider design that Volmer Jensen built. A continuing droop from root to tip 2.3 degrees without washout on the aft of the D section. Angle of Attack only 3 degrees, straight trailing ribs attaching ailerons and flaps. My VJ-23 hang glider didn't have a stall being able to fly at 15MPH, so Irv Culver being the Lockheed Skunk Works aerodynamicist was no one to ignore. The Shadow air foil is mine but it has that influence.

Structurally there are double safety applications. Bonding aluminium is difficult but backed up by mechanical fasteners. Cantilever wings with a flying strut, one not dependant on the other. Electric elevator trimmer has saved a landing when the push/pull Teleflex control was frozen. The tailplane vertical fins, for directional control saved Jas van Wyk in South Africa when a heavy bird strike broke off the entire rudder/fin. [see his heartfelt report on <davidcookaviator. Com>]. There is a shatter/destruct construction above the propeller arc.

Through the use of differing materials on the airframe it ended up not only lighter but stronger. Wood, Styrofoam, honeycomb, fiberglass, plywood, aluminium, steel, polycarbonate. Exotics like Accomet C, permanent Loctite, Safe T Epoxy, cellulose dopes, dress lining fabric, Araldite, Bostic glue, Nylatron, many others with special attention to reactions to each other like intercrystalline corrosion.

The initial flight circuit in an aircraft that one has conceived, designed and constructed is a mixture of fear and excitement, is probably the nearest that the Male Species is ever likely to witness to giving Birth.

David Cook