Hi Stef, One issue to resolve for yourself before aerobatics in your KR would be spins.
There have been discussions about un-recoverable spins in the KR. I’m not sure they are well informed, or just fears of the monster under the bed. However there have been a couple of tragic incidents (https://www.flyingmag.com/technique/accidents/aftermath-his-last-selfie <https://www.flyingmag.com/technique/accidents/aftermath-his-last-selfie>) (http://www.kathrynsreport.com/2013/08/kr-2-plane-crash-near-cataldo-idaho.html <http://www.kathrynsreport.com/2013/08/kr-2-plane-crash-near-cataldo-idaho.html>), so that monster has to be taken seriously till someone takes a peek. "Essentially, the first part of the flight was uneventful with the pilot performing some turns and steep banked maneuvers. Upon reaching the geographical area where the accident occurred, the pilot initiated an intentional spin, throttling the engine to idle, pulling on the carburetor heat, and increasing the nose up attitude of the airplane until it stalled and entered a spin to the left. During the first few rotations the engine quit, and the propeller stopped turning. After several rotations the spin stabilized about 20 degrees nose down, and remained in the steady state until impact. During the descent the pilot was observed attempting various control inputs without effect." It is important to note that unrecoverable spins can happen in almost any airplane: https://www.flyingmag.com/safety/accident-investigations/unrecoverable-spins <https://www.flyingmag.com/safety/accident-investigations/unrecoverable-spins> "PARE (not CIGAR, ARROW or GUMP) summarizes the proper actions for spin recovery. Power to idle. Ailerons neutral. Rudder hard against the spin. Elevator sharply nose-down (or nose-up for an inverted spin)." This is from the design analysis of the KR (http://kr2seafury.com/resources/1988_01_05.pdf <http://kr2seafury.com/resources/1988_01_05.pdf>): "He believes that going to the aft end of this en- velope will guarantee an unstable KR. Worse, in a departure or approach stall situation, a flat spin is likely to quickly develop and recovery would not be easy if even possible. Piper experienced this on the Cherokee 140. There have been cases where the 140 has gone into an unrecoverable stall-spin with the loading close to but still within the aft CG limit. In the author's opinion, the KR design is very similar to the classical Cherokee, except for the stabilator. The author would never purposely spin his KR, but will, by the same token, never load the plane such that the final loaded CG is further aft than 2 inches to the rear of the main spar aft surface. It has been tried beyond there and the re- sults are not pleasant. Wallowing, undulating and general instability show up back there. The answer? Consider defining the CG envelope as being only 6 inches long, and drop off the last two inches of the advertised envelope." If you search KRnet for “spins" (https://www.mail-archive.com/search?q=spins&l=krnet%40list.krnet.org <https://www.mail-archive.com/search?q=spins&[email protected]>) you will find a lot of discussion. Importantly, some with direct experience say the KR performs and recovers perfectly well in spins. The take home lesson: If you are going to do aerobatics, make sure your plane is loaded for a forward CG, that you start your exploration of the envelopes with lots of altitude, and if it were me, I’d have a parachute (which are required here for aerobatics) (https://airfactsjournal.com/2016/06/aerobatics-need-parachute/). Cheers, Owen > On Oct 12, 2018, at 9:00 AM, [email protected] wrote: > > Message: 4 > Date: Fri, 12 Oct 2018 12:20:45 +0200 (CEST) > From: Stef den Boer <[email protected] <mailto:[email protected]>> > To: KRnet <[email protected] <mailto:[email protected]>> > Subject: KR> Aerobatics > Message-ID: <[email protected] > <mailto:[email protected]>> > Content-Type: text/plain; charset=UTF-8 > > Hi, > > Bussy to finalize the paperwork and my pilot operating handbook. > > I know we there is a lot spoken about aerobatics, but is there a official > document thats approve the light aerobatics? > > > Stef > > > > Steph and his dad are building the KR-2S see > http://www.masttotaalconcept.nl/kr2 > <http://www.masttotaalconcept.nl/kr2>http://www.masttotaalconcept.nl/kr2 > <http://www.masttotaalconcept.nl/kr2> _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/[email protected]/. 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 [email protected]
