This is my first post on a thread so I hope this is the correct method.
You guys are on to something, a modern Aussie design that has similarities in concept to older US designs that are still in production like the Quad City Challenger, Rans Airaile, Quicksilver GT500 and Titan Tornado. Never hear of Kolb etc in Oz.
A lower cost recreational aircraft that is fun, safe, can take a friend for a ride, and could travel to a breakfast fly in or camping trip.
Some comments about the concept from a low hour pilot working towards aircraft ownership:-
Tail draggers look good, are simple, light, etc but most newbies learn on NW, so there is the extra cost to get a TW endorsement, and there are not that many schools with similar aircraft to the type proposed. The RAAus pilot average hours is apparently less than 50 hrs per year so being current on a TW is a potential risk factor. NW option will have much wider appeal.
Cruise speed not too slow, otherwise it becomes too limited, and the camping trip becomes an endurance test for the hardy types if there is a headwind. Faster than a trike would be good.
Airframe not too draggy and lower sink rate so has some glide ability for safety, nice not to have a high revving two stroke going hard just to keep it in level flight.
The aluminium tube and angle structure is a great well proven method,easier to analyse and build than composites and wood/foam. Easier to see for inspections, with less risk of possible internal flaws.
Covering could be a combination of fabric and aluminium, this has potential for a long life and a nice paint job.
Safety - needs structure to protect pilot and pax, and no strange handling quirks with doors off/on.
Fuel tank location and restraint for safety and ease of filling without risk of spills inside cabin.
Engine mounting not inverted like a Challenger, if two stroke need oil tank and pump no premixing fuel.
Four stroke engine option
Looks not ugly duckling, as people generally like to feel good when they look at their expensive recreational vehicle or are showing it to friends.
Consider trikes as potential competitors, they are popular, have cool factor and built in adventurer appeal. The popular brands also look well engineered.
The sketches look great, efficient engineering design is always a challenge, but can be very rewarding, so keep the creative thoughts flowing!