Andrew Angellotti founded spingarage, LLC to market disruptive flight test hardware. He uses a KR-2 for his test mule. I saw it at the Mohave Experimental Fly-in this year.
He's probably worth talking to regarding the KR's spin idiosyncrasies. Tristan > On Sep 13, 2017, at 7:28 AM, Jeff Scott via KRnet <krnet@list.krnet.org> > wrote: > > I don't know of anyone that has described slats or Vortex Generators (VGs) as > a spin prevention device. They may contribute in a small way by delaying > aerodynamic stall. However, if the plane can stall, it can also spin. > > Vortex Generators: There is a lot of debate an a lot of wild claims in the > STOL circles about the virtues of VGs on an aircraft. Many claim > significantly slower stall speeds, but in almost every case, actual testing > typically shows little to no difference in the actual stall speed. However, > what VGs do very well is to energize the airflow over the wing to delay the > detachment of the air flow. What that means to you as a pilot is that by > proper placement of VGs on the wing of your plane, the boundary layer has > more energy, and the ailerons will be much more effective through out the > slow flight regime right down to stall. Depending on the aircraft, there may > be a small reduction in stall speed. Nothing comes free, so there is a > penalty in drag that you will pay for installing VGs on your wing. > > I installed VGs on my extended wing SuperCub clone. On a plane as draggy as > the Cub, the drag penalty is unnoticeable, and I did indeed find that the > ailerons are much more effective in extreme slow flight and high angles of > attack. If they made any difference in stall speed, it wasn't really > measurable as my SuperCub Clone simply will not break into a clean stall from > slow flight. > > Slats: There's not much question that slats will delay aerodynamic stall at > high angles of attack. They capture a lot of air and direct it over the top > of the wing, creating an energetic air flow that will keep the flow attached > down to a lower speed. But there is a huge drag penalty to pay for this STOL > performance. The Zenith CH-750 is a good example of a plane with a fixed > slat. It will fly at extreme angles of attack, and incredibly slow. > However, cruise is also incredibly slow. Many of the Zenith owners are > removing the slats from their 750s as they are finding the plane is much > better mannered without the slats, cruises significantly faster, and looses > so little in slow flight/stall speed that they find the trade off to be > better without the flaps. > > Aerodynamic Slats: Aerodynamic slats are becoming all the rage with the STOL > crowd. Many of the Valdez competitors are now sporting aerodynamic slats. > The Cub style has a slat that pivots on the mounting standoffs, so they close > off relatively cleanly for cruise, and pop open at high angles of attack. > There is both a weight and drag penalty to be paid by adding these to your > wing, but they are an easy retrofit to install. The Pegazair style has a > slat that rolls straight out of the leading edge. I have flown with this > style and found them to be highly effective and clean for cruise flight, but > this type has to be designed into the wing before construction and also comes > with a weight penalty and some complexity added to the wing build. > > I wouldn't think VGs would be a good solution for a KR. They will not > prevent the wing from stalling, and are unlikely to noticeably lower the > stall speed. They will not prevent a spin. However, they will make the > ailerons more effective down into the stall. That's not something I have > really found a need to have, and I would not be willing to pay the drag > penalty on a clean plane like my KR. > > Regarding spins in a KR. I have spun my KR. It's been a number of years > ago, and I did not allow the plane to go past a single rotation, so didn't > allow the spin to fully develop. However, I did find my KR recovered the > same as the numerous other planes I have spun. An additional note about > spinning a KR. KRs are notoriously tail heavy. Mine was nose heavy enough > at the time that I spun it that it required a miniumu of a 110# pilot to get > it into the forward end of the CG, so I would expect it to recover quite > easily. Over the years, with the addition of equipment, weight gain by the > pilot and the replacement of heavy engine accessories with light accessories, > the CG has moved aft quite a bit. I would not intentionally spin my KR > today. However, I am still confident that if I did, it would still recover > from an undeveloped spin. > > If spins are something that concerns you, I would recommend getting some spin > training to the point where you become comfortable with spins. In the > process, you will also become confident that you can avoid the stall/spin > scenarios. > > -Jeff Scott > Los Alamos, NM > > > ---------------------------------------------- > > Found the link: > > http://www.stolspeed.com/slats-v-s-vgs > > Henni, > South Africa > > > -----Original Message----- > > Hi again all, > > After reading about the incident where a KR2 pilot was killed when he > deliberately put it into a spin, I searched everything on the web that I > could find about spin prevention. > > http://www.flyingmag.com/technique/accidents/aftermath-his-last-selfie[http://www.flyingmag.com/technique/accidents/aftermath-his-last-selfie] > > Must say, every single article lists vortex generators on the wings as a very > good method of preventing spins to some degree. This have been something that > I have always wanted to implement. > > I once read an article that the vortex generators worked so well on a certain > light aircraft that the manufacturer stopped producing it with slats in the > leading edge of the wing. The VGs achieved the exact same results without the > slats. > > I now from a lot of reading that one will only loose around 3mph due the > vortex generators. On the other hand, they will also reduce the stall speed > by same. Plus, they are so easy to install - just glue them on using double > sided adhesive strips > > This is something that I am definitely going to implement on my project. > There is no weight penalty at all, we're talking ounces only. > > Anyways, something to consider. > > Henni, > > South Africa > > > > _______________________________________________ > 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. 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