I am using the thicker airfoil with the taper. The reason I hacked out the spar is because I am going to increase my center spar length to about 10'. I am doing that for a couple of reasons. One is because I want big flaps in the center section. The second reason is because I am doing away with the header tank and putting all my fuel in the stub wing tanks. One time hanging upside down from the seatbelt over a burning header tank is more than enough for me. It will also allow me to have a removable front deck to get to the avionics and rudder pedals easily, and maybe even a small forward baggage compartment. I wouldn't do away with the header tank with the VW, but since I will use a Corvair with a mechanical fuel pump and an electric boost pump I have no problem not having gravity feed.
I plan to have a pretty good amount of fuel in the stubs. I have done a 4.3 hour cross country in a KR before, and I can easily go 6 hours and I like to have reserves. I also like the idea of having my C.G. not moving way aft as I burn fuel like it did with the header tank. I realize that I could have had the fuel and the flaps in the outboard wings, but it seemed like it would be a lot easier in the stubs. If I keep the same tip chord and wing span I will be increasing the taper ratio of the wing a lot which does not help spin characteristics any. It also decreases the aspect ratio which hurts speed. I may decrease the chord in the stubs a little so I can keep a higher aspect ratio and not increase the wing area so much. Whatever I do, I will run the options by an aeronautical engineer first. I will probably increase the wing area a little. I will have more than enough speed with the Corvair and I don't mind trading off some of it for a higher gross weight. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of Mark Langford Sent: Friday, May 07, 2004 4:12 PM To: KRnet Subject: Re: KR> outboard spars for sale Brian Kraut wrote: > I tried to remove my center section forward spar today without damaging it, > but no luck. It does come out very easily though when you saw it off with a > sawzall and remove the remaining pieces with a wood chisel. Brian, I assume you're planning on using the thicker 18% AS 5048 airfoil tapering to the 15% AS5046. Otherwise, if you are simply swapping to the 16% AS5046, you don't need to change the main spar at all, or replace the outer spars. Just didn't want anybody to get the impression that changing to the new airfoil required hacking the main spar out. More info on the airfoil is at http://www.krnet.org/as504x/ , with installation instructions at http://www.krnet.org/as504x/ . The thicker airfoil gives you more room for fuel in the wing tanks, and the potential for a main spar that is either lighter or stronger than the plans version (due to it's extra height), whichever you decide to use. Mark Langford, Huntsville, Alabama N56ML "at" hiwaay.net see KR2S project at http://home.hiwaay.net/~langford _______________________________________ to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
