If you are using the Nyrod trim as shown in the plans, it seems to be a bit problematic. I installed the Mac (now Ray Allen) trim servo in my KR when I was building. When I rebuilt the tail at a later date I tried a spring assist trim, that really didn't work. I later retrofitted a new Ray Allen trim servo into the elevator and used the old Mac servo to operate the cowl flap. Neither servo ever gave any issues, and have always been rock solid.
I used a similar push/pull type trim control per plans when I built my SuperCub Clone. It was functional, but eventually broke while trimmed nose down. A lose trim control can go into a violent flutter, which is what happened on the Cub. I also converted it to a Ray Allen servo, which has served me well for the last 8 years. The RV also has Ray Allen servos for both Elevator and Aileron trim. It's simple and will put an end to your trim woes. Retrofitting the Ray Allen trim into a KR elevator is shown in reasonable detail on my web site at <http://jeffsplanes.com/KR/2013_Trim.html>. I had the elevator off to do the retrofit, but that was just a convenience since mine was removable. But it could just as well be done with the elevator still mounted. It would just require a lot more time laying on your back on the floor. -Jeff Scott Arkansas Ozarks > Sent: Tuesday, November 17, 2020 at 2:59 PM > From: "Samuel Spanovich via KRnet" <krnet@list.krnet.org> > To: krnet@list.krnet.org > Cc: "Samuel Spanovich" <spanovich...@gmail.com> > Subject: KR> Elevator Trim Adjustment > > Hey guys; this weekend if the weather cooperates I am going to try to correct > an issue that I’ve had for quite some time now. > > It seems that my elevator trim is not doing its job properly. Whenever I am > flying by myself, the plane will nose over slightly when I release the stick, > even with full up elevator trim. When I have a passenger, and am approaching > gross weight, the issue is still there but not nearly as bad due to the CG > being further aft. > > I took a look at my trim last time I was up at the hangar, and even with full > up trim, the trim tab moves a lot. I understand it is supposed to move > slightly as the elevator travels down and up, but this feels way more “loose” > than anything; I can basically move the trim tab full deflection up and down > at all times, even with full up trim. > > I was curious if anybody has had this same issue, and if so, is there an easy > fix for it? I’ve essentially just ran out of elevator “up” trim. Would this > just be a matter of tightening the trim tab cable so the trim tab is more > sturdy, or is this something aerodynamic related to the Stock KR2S that would > require major modifications? > > I do not mind having my hand on the stick the whole time, but my fear is if > the elevator cables were to ever fail in flight, I would have zero redundancy > for the flight controls. If my trim tab was adjusted correctly, and the > cables were to fail, I could (in theory) use the trim tab to give me some > influence of pitch and at least make an effort to get to a runway. > > Any help would be greatly appreciated. > > For reference; > > -Stock KR2S; RAF48 airfoil. > > ~650 lbs empty > > -Revmaster 2100D; battery forward of firewall > > -CG is near the forward limit when completely empty. > > V/R > > Sam Spanovich > N6399U > 74S, Anacortes WA > _______________________________________________ > 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