Fair enough. The similarity between the model and the kr is too much to ignore though. What works for the model will most probably work for the kr.
Tail design no 2 from the paper seems most promising. The rudder is cut off below the elevator and that increases the yaw damping moment. A bigger stabilator further aft will increase the tailplane moment arm and unshield the fin and rudder. Of course the rudder needs to go all above the horizontal stab. That means a taller fin. I think the kr tail, Tail no 3 from the paper, is prone to flat spins because the rudder below the elevator is shielded by the fuselage and does not contribute to yaw damping and the rudder left above the elevator does not have enough area and is shielded by the elevator. Unless you are thinking of another fin under the elevator then a taller fuse aft and more rudder wouldn’t help. > On 15 Oct 2017, at 19:35, svd via KRnet <krnet@list.krnet.org> wrote: > > > > >> On Oct 15, 2017, at 9:00 AM, krnet-requ...@list.krnet.org wrote: >> >> Making the mods is just down right cheap. Then we can all practice spins in >> a KR. Makes it more attractive to a lot of people. Lets fix this. > > > As previously noted. A major point of this paper: >> https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770026167.pdf >> <https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770026167.pdf> > is that while mods can help, it is unpredictable whether a particular mod or > recovery procedure will help. > > this is compounded by the fact that homebuilt airplanes vary so much between > individual airplanes of the same model. > > how valid the paper is I don’t know, but I do know that they are way more > qualified on matters aerodynamic than me. > > However, accumulated experience and understanding in GA design in the 40 > years since the paper was written (and 45 years since the KR design), suggest > some basic design features (mods) that can increase spin resistance and aid > spin recovery (very separate issues). > > Icon Aircraft wing design was the first production aircraft to comply > completely with FAA spin resistance standards. Its t-tail gives it spin > recovery (and helps with the high center of thrust issue), but spin > resistance is more an issue of wing and fuselage design: > > https://www.google.com/patents/US20140021302 > <https://www.google.com/patents/US20140021302> > > In Icon’s case, wing cuff with airfoil changes and wingtip, funnel airflow > over the ailerons. > > I would suggest that the easiest changes for the KR would be: > Spin avoidance / resistance: > 1) sight line AOA (to help keep you away from stall). > 2) Stall fence between wing stub and outer panel. > 3) Stall strip on inner wing stub > 4) VG’s on outer 1/3 of wings. > > Spin Recovery: > 1) VG’s on rudder bellow stabilizer. > 2) Increase rudder area below stabilizer > > We will probably incorporate or test all of these mods, but won’t be flying > until summer at the earliest. > > Cheers, > Owen > > > > > _______________________________________________ > Search the KRnet Archives at > https://www.mail-archive.com/krnet@list.krnet.org/. > Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options. > To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
