👍👍👍👍👍👍👍👍👍👍 On Thu, Jul 14, 2022 at 12:03 AM colin hales via KRnet <krnet@list.krnet.org> wrote:
> 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. > > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet >
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