Only 3,000 RPM? I seem to recall that mine was 3,200. When I changed to the new Sterba prop I believe it increased to 3,400. I vaguely seem to remember a 10MPH or so speed increase, but what I can't forget is the dramatic increase in climb rate.
-------- Original Message -------- Subject: KR> differences between the KR2 and KR2S From: "Mark Langford" <m...@n56ml.com> List-Post: krnet@list.krnet.org Date: Mon, September 03, 2012 7:55 pm To: "KRnet" <kr...@mylist.net> Stephen Teate wrote: >>I bet others have already asked, but given the difference in engines I >>would be interested to know if there are any performance differences in >>the two wing choices for the KR now that you have flown both.>> KR2S N56ML has the AS5046 airfoil, while KR2 N891JF has the RAF48 airfoil. I already knew this (having flown several KR2s before I flew my S), but there's a real difference in the feel of the ailerons between the two. N56ML requires probably half the force required to make a turn, partly because of the cusp on the bottom of the AS5046, which loads up the controls with upforce on the bottom of both ailerons and stiffens up the aileron control circuit. The KR2 rolls very quickly and easily by comparison. But another part of the equation is that N56ML has the ailerons on the outer half of the wing and they have probably twice the chord, so that's another contributing factor. The stall is different as well. The KR2 gives so much warning I felt as though somebody was back there shaking the horizontal stab up and down. I never did get it to actually break loose, and I had no doubt that it was technically stalled, given the decent rate. N56ML gave much more subtle indications that it was near stall, and eventually it would have a real break to it that would really get your attention, if you carried it that far into the stall, but it was technically stalled (losing lots of altitude) way before that. The RAF48 might do that to, but so far I haven't been there. That's not to say that I'm worried about the AS5048 sneaking up on me. You'd have to be stupid to not notice that it was getting a little squirrelly and that the airspeed was almost off the scale. I still highly recommend the AS504x airfoil, as it's a free lunch from the speed and endurance standpoint. The lack of turbulence might be specific to my airplane though, since my ailerons are out past the horizontal stabilizer, and there's no gap beneath the flaps to set up turbulence back at the stab. And what turbulence the tail sees on N891JF comes from the turbulent RAF48, which is probably more than you'd get from a more laminar AS5046. I've said many times that if I already had n RAF48 wing, I'd fly behind it and be happy about it. It's not worth the year of downtime to change an RAF48 to an AS5046, unless speed is your ultimate goal. As for other performance, the planes are too different to compare from a speed standpoint. N56ML is probably 40 mph faster (pending ASI calibration), so that's a significant number, and it's bigger, but it also has 70% more power. So far I haven't been able to get over 3000 rpm on the 2 in straight and level flight, so I suspect I need a little less propeller pitch to get it up in the horsepower range where I like to live. The GPASC 2180cc engine is supposed to be turning 3400 rpm to get 70 hp, and it's a long way from that now. N891JF is a little more sensitive to pilot input than N56ML. I find myself doing some minor PIOs when trying to feel for the ground sometimes when landing. No big deal though, and out of the 25 or so landings that I've done so far, I haven't done one I'd call "less than good" yet. I should probably find some wood to knock on though! I have a lot more to learn about the differences in the 2 and the 2S. Weather permitting, I hope to fly in some calm air Wednesday morning and do some calibration on the ASI, which I already know is reading high. I may fly down to my father's farm next weekend too... Mark Langford ML at N56ML.com website at http://www.N56ML.com ------------------------------------------------------- _______________________________________ Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
