> Sent: Sunday, March 15, 2020 at 2:41 AM > From: "Mike Stirewalt via KRnet" <krnet@list.krnet.org> > To: krnet@list.krnet.org > Cc: laser...@juno.com > Subject: KR> Dan Diehl's comment to Lee > > > > "With all that being said, Dan Diehl once told me that he would build > another KR2 and change the angle of attack of the RAF airfoil by 2 > degrees, so the speed of the plane would not make it Plow through the > air. And increase airspeed by the loss of drag." > > Interesting Lee. Without a clear idea of what I'm thinking on this > subject, that 2 degree "change" Dan is talking about must be calculated > based upon a particular indicated airspeed - probably a number he chose > as a "normal" cruise speed for he KR - somewhere around 150 MPH I'd > guess. > > Just thinking out loud here . . . but if angle of attack decreases with > an increase of indicated airspeed, and also with a decrease in air > density . . . cruising at higher altitudes lowers the AofA for a given > indicated airspeed, thus eliminating or minimizing that "plow" effect you > mention. Also, I think Dan was referring to angle of incidence (wing > chord in relatioship to level fuselage), and not angle of attack. AofA > can be all over the place depending on speed and also depending on the > angle of incidence and aerodynamic effect of a smaller or larger > horizontal stabilizer. > > ************************ > > Once I've got my ADS-B stuff installed and am flying again, I'm seriously > planning on adjusting my ailerons to trail in the neutral position with a > 2 or 3 degree up (negative) angle. Sailplains do it so it should work > for KR's too? I'll report on this someday. Surely somebody has played > with this idea after all these years? > > As long as one is playing with ailerons, it sould sure be nice to > incorporate the ailerons as flaps, ala the Robertson conversions and the > Helio Courier and a number of others. That's a bigger job than I'm going > to fool with but adjusting the ailerons to neutralize at 3% up when in > trail seems easy enough, at least in my head. Such as it is. > > Mike > KSEE
***************************** This goes back to the thing about many thinking the KRs are cruising with the nose down. I heard a lot of criticism of the KRs for that some 20+ years ago and that was part of the impetus for the creation of the new wing ws to correct the incidence of the wing. While it may be true that some of the KRs are flying a bit nose down, that really depends on the altitude and the speed of the aircraft. The faster they are flying, the more they are pitched down, so with the installation of bigger engines making for faster aircraft, especially at lower altitudes, some of them are pitched down a bit. But it was especially noticeable back in the 90s when a number of the guys were doing hot passes down the runway at the KR gatherings. I'm not sure it occurred to some of those observing that those nose down passes were being made at speeds well above cruise where the aircraft has to be pitched down to keep it from climbing. As Mike surmised, yes, reflexing the aileron adjustments up and down is something I experimented with a number of years ago. Reflexing the ailerons up a bit effectively reduced the overall angle of incidence of the wing, but too much of an adjustment put the ailerons out of trim from the rest of the wing, so they start to generate more parasitic drag. Additionally, reflexing the ailerons up opens up the aileron gap a bit and on my wings starts to drop the aileron counterweights out into the slipstream, both of which will generate a bit of drag. Reflexing the ailerons down had the opposite effect by adding a bit of overall incidence to the wing, but was also not beneficial to get the ailerons too far out of alignment from the rest of the air foil. For my KR, I found the best adjustment to be with the ailerons set to be consistent with rest of the wing airfoil. At the time, I was doing my testing at 8500'. In all likelihood, now that I'm living and flying at lower altitudes, my aircraft might actually benefit from reflexing the aileron adjustments up a turn or two. -Jeff Scott Arkansas Ozarks _______________________________________________ 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
