I'll say it's pitch sensitive. It is also dynamically unstable in pitch. Whether builders want to accept it or not, the original KR-2 tail in the plans lacks sufficient horizontal stabilizer to stabilize it in flight. The lack of stabilizer makes it very sensitive to upset by control inputs and dimishes the feel in the stick. It is a common problem with home built designs but the KR is one of the worst offenders in tail design. By anybody's measure, the KR has an unusually small tail as compared to the wing area. The short fuselage only exacerbates the problem.
If this wasn't an issue, why has the forum always had discussions about how to hold the stick with you wrist stabilized on your leg or an armrest or something else stable? What other plane needs that kind of a crutch to aid the pilot in flying straight and level? I flew my KR with the plans built stock KR-2 tail for 500 hours. You can learn to adapt to it. I did in about two flights and never really had a problem flying it. But that doesn't make it right. After 500 hours flight time I cut the tail off my KR and built a new stabilizer using the airfoil from Mark Langord's web site using an 8 foot span (vs the 6 foot original span). I've flown the plane another 390 hrs since changing the tail. The change in stability was dramatic. The elevator is still quite light, but the instability is gone. The larger tail in no way diminished the sporty feel of the plane. It only made it easier to fly and added a little bit of feel to the stick. As for the question about vortex generators on the tail, they help keep the flow attached to the elevator at high angles of attack, making it even more effective. I wouldn't expect VGs to help address the issue as described in your post. FWIW, I recently purchased and installed Vortex Generators on my SuperCub. I didn't install them on the tail as mine really doesn't show that it needs to be more effective even at very high angles of attack. The VGs on the wing didn't lower the stall speed, but did keep the flow better attached up to the point of stall, so the plane flys much more stable with a lot less wallowing around in slow flight (27 mph IAS). OK, you can accuse me of heresy , but I don't know of anyone else that has flight tested and flown significant hours in their KR with two vastly different tails. Note that I have not tested the slightly larger -2S tail. I have my expectations of how it would fly, but since I have not flight tested it, I won't comment. Jeff Scott Los Alamos, NM ----- Original Message ----- Who says the the Pitch is sensitive ? Virg On 5/1/2012 4:08 PM, Robert Boyd wrote: > Just wondering, Instead of adding some length to my horizontal > stabilizer, would adding some VG's to the underside of the elevator do > anything to help with pitch sensitivity?
