SkyRanger UK Certification

The SkyRanger design has been proven fully compliant with the British Section S airworthiness requirement. Certified through the British Microlight Aircraft Association, the testing involved an in-depth look at stability and control, performance, stalling and spinning characteristics.

The stability testing covered stability assessment of all axes, and through a range of Cg positions.

Control tests also investigated authority and ease of control in all axes, Cg positions and airspeeds from stall to Vdf - which involves diving to earth at full power at well over the eventual Vne speed!

Stalls were also investigated working from forward to aft Cg positions and working up to accelerated entries at all power settings - the full power accelerated entries result in some spectacular nose up attitudes before the stall!

Spinning was also investigated. This is a recent Section S requirement and is there to guarantee that if a pilot inadvertently enters a spin the aircraft will always recover without special control movements or skill. To ascertain this a program of over 100 spins were necessary to cover all possible Cg positions, power and flap settings and types of entry.

Performance testing covers takeoff and landing distances, climb and glide rates and maximum level speed.

We were not too unlucky with the weather and the test program took a little over 6 weeks to complete and has involved nearly 30 hours of flight time and around 200 hours of preparation and report writing. The program culminated in the BMAA Chief Technical Officer Guy Gratton spending a day flying the aircraft through a range of tests himself. At the end of this he pronounced himself more than happy with the aircraft, and commented that the testing had gone very smoothly - which is very unusual in his experience! - surely a testament to the integrity of the aircraft. He was impressed with the ease of cockpit access, the in-cockpit visibility for this layout of aircraft, the spirited climb performance, and top speed for an aircraft of this construction medium, and the viceless handling during stalls etc.

So the Skyranger was found to have no vices, exhibits excellent takeoff and climb performance and a good turn of speed. The controls are powerful without being twitchy and make tasks like crosswind landings a breeze. Stability is high with the aircraft exhibiting good hands off stability - ideal whilst eating that sandwich on your long cross country! Stalling is benign even at full power settings. The spin trials revealed good manners and recovery is instant as soon as controls are returned to the neutral position. What we appear to have is an excellent safe, cruising aircraft with spirited performance.

The first 25 hours of the test program was flown with the 2 blade GT prop fitted. This gives a nice relaxed cruise performance and 'real aeroplane' looks. Later tests used the Arplast Ecoprop 3 blade composite propeller. This has ground adjustable pitch setting. At the current setting this prop is giving us improved climb performance - Guy Gratton recorded a solid 1000 FPM climb at max takeoff weight and nearly 1500FPM when flown solo. Cruise requires a little more revs but is smoother and top speed is increased by a couple of knots.

Testing is also complete with the 2 blade GSC prop as our budget option and we also have a Ukrainian 'Kiev Prop' 3 blade composite which looks fabulous and has inset brass leading edge protection. This prop has now been fitted to G-CBIV (our original test aircraft) since completion of the test program, and still looks as good as new.

 

During the certification process, we have made a number of changes/ enhancements to the aircraft; which have now been integrated into the standard kit worldwide.

The pitch trimmer system has been redesigned. This was to comply with the strength and irreversibility requirements of Section S. In doing so we have also moved the lever to a position on the overhead cabin structure. This has the advantages of de-cluttering some of the space between the seats, and improving the linearity and smoothness of the lever action. The change also allows a trim position indicator.

The throttle levers have been redesigned to comply with the strength and stiffness requirements of Section S. One test requires proving strength when one pilot pushes his lever with all his might whilst the other pulls in opposition. And when we are talking all their might we are talking the Arnold Schwarzenegger brothers!
We now have a very stiff throttle lever system which allows precise throttle control from either seat, with improved friction control. We have also taken advantage of the change to tuck the torque tube up a little further behind the instrument panel, increasing shin room and tidying up the appearance a little.

We have opted for the split doors on the test aircraft. The lower half is hinged on the forward edge and the upper half is top hinged and can be opened in flight. This complicates the flight test plan a little but we believe is more than worth the effort. Tests include establishing a max door open speed and investigating stability, control, stalling and even spinning characteristics with the doors open. Philippe (the designer) was surprised when we opted for the split doors and said "surely in Britain it is too cold to fly with the doors open?". We replied that they would be useful for when the windows iced over in flight, and could be opened for clear vision!
In trepidation of the flight test program we have re-designed the doors a little and the top halves now have larger stronger frames!

We have also been working at defining the UK standard for the electrical system, fuel system, and various other odds and ends so that the UK kits can be supplied with the engine fitting kits with cut to size components. This has taken a lot of work and time for us but should result in significantly simpler and faster build times for you guys.