The whole idea about small aircraft is, to get them to perform you keep them light! To add a heavy weight on an electric motor to move the C of G around doesn't help with keeping the aircraft light. That is why no one does this. Why would you want to add weight??? Just have space on the rear parcel shelf or make space for a forward baggage bay to help you load the aircraft to assist obtaining the required C of G.
My KR2 cruises about 5 to 10 knots faster with the C of G on the aft limit of 6 inches. So that is where I fly them. I made the empty C of G as far forward as possible, so that when you fly with a passenger, the aircraft still remains within the aft limits, but without a passenger I place their parachute, yes I fly with a parachute on all the time, I place their unused parachute on the parcel shelf behind my head to place the C of G further back. At 6 inches aft, the aircraft becomes neutrally stable. Any further beyond that, the aircraft is still controllable, but the stability is divergent and you can't let go of the stick. You asked, "Since CG location is such a critical and sensitive element on aircraft safety, why there hasn't anyone in the experimental world tried to resolve this issue by design?!" They have done this!!! It's called the RV6 or RV7 or so many other aircraft that don't suffer from C of G issues. The Kr2 only suffers from C of G range issues because the pilot and passenger sit so far beyond the C of G and the weight of Pilot and Passenger can be up to 40% of the total weight of the aircraft. There is nothing you can do about this, but set the empty C of G so far forward that when you are solo, a balance weight is unfortunately needed on the parcel shelf, but when flying with a passenger, the aft C of G is not exceeded. For myself, to work out where the C of G is on my plane, because I know them so well, I just lift the tailplane. If it lifts easily, then I'll move something from the front bay and put it on the rear parcel shelf. When I left Alaska for Russia, laden with 220 litres of fuel on board, or 55 US gallons. I could hardly lift the tail wheel off the floor and knew already, without scales or maths or charts, that the C of G was beyond the aft limit, in the divergent range. I only just had enough forward authority for safe flight and did nothing for an hour or two until I had burnt off some fuel from the main tank and could pump some in from the fuel bladder on the parcel shelf. SO as long as you are thoughtful and don't do anything stupid, safe flight is possibly, even when pushing the boundaries. But personally, I think you are over thinking all the issues. Finding problems where there are none. The biggest problem you are ever going to have when building and flying a Kr2 at any time ever, is finding the time to finish building the plane in the first place. SO stop writing on here about what other people might or might not have done and simply concentrate on finishing the best lightest simplest plane you can build. Do that and you won't have any of these problems you keep thinking up, that don't really exist. Just get on and build... CH.
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