Chris Holloway's work had progressed through many variations over the years and had finally ended up with a conventional fuselage, very large slab style wing with floats that also served as end plates, two ducted fans on the front, firstly to reduce propeller size and also to blow air under the wing in take off, and a huge tri-tail to ensure directional and roll stability.
Tests with this model prior to the Radacraft project proved very successful although it demonstrated some characteristics that Mr. Holloway did not like, for example, for balanced lift off and flight the center of gravity was at 2/3 chord, this reduced longitudinal stability at altitude, increasing oscillation in disturbance and accentuating the potential for "blow over". The slab wing configuration also had some severe stall characteristics, certainly not a comfortable thought at such low altitudes.
A clean sheet approach was taken to the design of the G-35. Again a conventional fuselage was chosen and twin ducted fans were placed forward to give power augmented ram air for assisting in takeoff . The same main wing profile as before was chosen although a seven degree twist was installed to make the craft "stall proof" and it was swept forward to help the roll stability. The tail section was formed dihedral to compensate for the twist in the main plane and still had quite significant vertical stabilizers for directional control. These decisions were basically made before a pen was placed to paper. The G-35 was then visualized and given life.
The G-35 started it's life as a series of concept images which were then converted into two dimensional Autocad drawings, showing basic layouts for discussion and analysis. Two highly respected aerodynamicists were then added to the Radacraft project team. They were responsible for the inclusion of the winglets that ultimately had quite a dramatic effect on the craft's performance.
The two dimensional drawings were extended to three dimensional wire frames and all the parts were simulated.
These parts were then put together and rendered so that visualization of the finished craft was possible. This allowed us to assess the finished craft from all angles prior to the build.
A hard wind tunnel model was crafted and the Royal Melbourne Institute of Technology's Sir Lawrence Whackett center was contracted to conduct the testing. Their team included, Peter Coates (who is pictured here) Jon Carboon and Lachlan Thompson, whose other work includes the successful Olympic bicycles.
The results were better than expected and work began on building the G-35. Sea trials began just after Christmas 1995 and of course all of the things that had not been considered in the design such as Hydro-dynamic drag and its effects on boat speed, given the chosen hull and propulsion systems, the suction effect of the water at the craft takes off and the airflow interaction as a result of the semi submerged floats that was not replicated in the wind tunnel testing. Many changes were made to try to improve the lift off characteristics although most of these changes only served to increase the weight of the craft which finally ended up at 1350Kg MTOW nearly double its original design weight. A more powerful engine was installed to compensate the extra weight and finally showed not only the success we wanted but with the installation of a radical new under carriage reduced hydrodynamic drag and increased our operational flexibility.
The G-35 seen here operating over land and water was severely damaged in a road transport accident totally destroying the tail, demonstrating that although the craft had no tail section it still performed quite admirably in extreme ground. It is worth noting that a height of 500 mm only was achieved without the tail before the craft became uncontrollable in pitch.
This work without the tail showed the inherently stable characteristics of the G-35 and all augers very well for the next generation of Radacraft. The Radacraft C-850.
Built to skim one metre above the water or land at better than 125 km an hour, the Radacraft would be able to carry passengers or commercial loads to out of the way places without any special landing spaces or docking facilities.
The Marine classification of Radacraft reduces the certification costs involved in development (compared with aircraft), thereby lowering the unit costs.
Composite construction was chosen to ensure a simple, cost efficient, strong and corrosion free structure, so as to reduce both manufacturing and maintenance costs.
Operating in Ground Effect, fuel savings of 40 to 50 % over Aircraft are possible.
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