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
