There's published numbers and then there's reality. If the published empty weight, range and cruise numbers are anything to go by, the published stall speed might be suspect.
Having said that, there are several KRs on the recreational register here in Oz, and that requires a stall no greater than 45 kts (51.8 mph) in the landing configuration. So it can be done without getting too adventurous with mods. Cheers, Tony On 17 March 2016 at 13:50, Chris Prata via KRnet <krnet at list.krnet.org> wrote: > this is interesting. LSA specs say 51MPH max stall speed without using > flaps. > I looked up the specs, and the KR1 easily meets the stall speed specs at > 45MPH stall. (so with fixed gear, modest power and and a climb prop, I will > be all set to fly under LSA rule) > The KR2 is published as 52 MPH stall. Thats only one MPH. Couldnt you get > there with VG's? > Also, I dont see flaps mentioned one way or the other on the KR2 perf > spec. Maybe thats the catch? > > > To: krnet at list.krnet.org > > Date: Wed, 16 Mar 2016 20:56:18 -0500 > > Subject: Re: KR> Wing Extensions > > From: krnet at list.krnet.org > > CC: ml at n56ml.com > > > > > > Steve Goosic wrote: > > > > >>Since my wings are already built > > (RAF48), do I extend both wing spars or is it possible to add additional > > foam to the existing wing end and shape to form? Also, how much further > > do the wings need to be extended?<< > > > > See http://www.n56ml.com/900hour/ for how I extended my KR2S wings 14". > > Also, below is something I posted to KRnet at about the same > > timeregarding the same question. I fished this out of the archive, at > > http://tugantek.com/archmailv2-kr/search. There's plenty more on this > > subject there as well, but below is a pretty good summary. Bottom line > > is that the plane has to be very light (like same KR2 gross weight) to > > get away with adding only a few inches to each wing. > > > > Subject: Re: KR> longer wing panels, etc. > > From: Mark Langford <n56ml at hiwaay.net> > > Date: Sat Jul 10 19:37:54 MDT 2010 > > > > Tom Garner wrote: > > > > > My hope is that some young bright engineer will come up with a wing > > design > > > to make KR2-s comply with LSA requirements. Outer wing panels of > > > course, not a total rebuild. > > > > That's not as difficult as it sounds. You almost don't need any math to > get > > there. If you believe the stall speed numbers published for the KR2, > about > > all you have to do is increase wing area by the same percentage you want > to > > drop the stall speed to get under LSA requirements. Of course your gross > > weight may be higher, so you've got to do that twice. And if the > published > > numbers are optimistic, you might build in another fudge factor. > > > > And then there's just spending an evening doing homework by reading stuff > > like John Roncz's ""Designing Your Homebuilt" from Feb 1990 Sport > Aviation > > magazine or "Sizing Your Wings", or something similar. His spreadsheets > are > > floating around on the web also, which make it even easier. Coefficient > of > > lift is given in info on one of the links from the AS504x webpage at > > http://www.krnet.org/as504x/ . There are several variables involved in > > upsizing the wings for YOUR airplane, so rather than have somebody do the > > work for you, I'd recommend doing it yourself for your airplane. > > > > There's a basic equation the FAA might use to give your design a > > "reasonable > > test" for stall speed, and all you have to do is meet that (you'll find > it > > in the Roncz works). And I'd name the airplane something other than a KR > > also, because the KR2 and KR2S already have "hard" stall speed numbers > > published by the manufacturer, so to keep from muddying the water, call > > your plane something other than a KR. > > > > But the bottom line is that you could almost guess that an extra few > inches > > longer than the Diehl wing would get you into LSA territory. You just > > need to be able to whip out that calculation when the FAA guy asks for > it. > > But you might want to use the 18% AS5048 airfoil to get deeper and > > therefore > > stronger spars in the deal. > > > > And if the plane's already been registered as an experimental, it's too > > late > > to call it an LSA, although I believe it can still be flown as an LSA. > The > > other part of that is the max speed, so you'd need a small engine or a > > fine-pitched prop to keep from exceeding it. > > > > Gotta get back to the hangar for another round with the vinyl ester fuel > > tank... > > _________________________ > > > > Mark Langford > > ML at N56ML.com > > http://www.n56ml.com > > > > > > _______________________________________________ > > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > > please see other KRnet info at http://www.krnet.org/info.html > > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to > change options > > _______________________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options >
