Steve plug the info you just quote into Aiplane PDQ and the program will do all the calculations, show boundary layer, separation points, drag figures as well as a the Reynolds numbers involved and can show what if any changes will occur prior to actual modification. It will also show what changes will occur as airfoils are changed and allow you to choose the most optimum foil for your intended use. The thing I enjoy most about the program however is the fact that it will show angles of attack where to expect stall and how violent they will tend to be as well as give the builder a realistic cruise and Vne for the engine installed. Any and all variable are dealt with and fully editable. From there it is simply a matter of feeding the information into X-Plane and you are able to get a feel for how the finished product will behave on completion. It is possible to rack up many hours of simulator time for your particular bird and therefore better prepare you for the flight testing stage. I have found that over my career that my personal dislike for surprises has kept me alive in more than one hairy situation that one would not otherwise think of. Doug Rupert Simcoe Ontario.
-----Original Message----- From: krnet-bounces+drupert=sympatico...@mylist.net [mailto:krnet-bounces+drupert=sympatico...@mylist.net] On Behalf Of Stephen Jacobs Sent: Sunday, April 18, 2004 5:10 AM To: 'KRnet' Subject: RE: KR> Stick angles/incidence angle/trim tab >> At 155 indicated my KR, standard wing built to plans, appears to fly >> with the nose down at a -2 degrees. >>> I did a quick check yesterday and found that my trim tab is "down" >>> (for nose up trim) at 155mph >>> My C.G. on that flight was probably about midpoint of the range >>> I tried to set my H.S. to zero degrees with the fuselage level and >>> that required a small shim under the forward spar Great stuff here, thanks Larry. I assume your KR is rigged with the standard +3.5 positive wing incidence at the root. We know the HS is zero (with a 24" longer moment) and you still need some of "up" trim in the cruise with a relatively neutral CG - I am really surprised and pleased to know this before I finalize anything. Assuming also that you used the typical 2 to 2.5 degrees washout that appears to be normal amongst builders - it looks like the relationship between the wing root and HS of +3.5 is about right (if not a little shy) - say 4 degrees decaulage should be pretty close. (For an RAF48) I would have expected this to be less - 2 to 2.5 degrees (with -2 washout). Maybe there is an influence from the other dimension - thrust line. I would imagine that your thrust line is pretty close to zero and thus effectively 2 degrees down thrust in the cruise. This may tell us why your bird is looking for a bit extra "up" in the cruise - to compensate for the engine pulling down. Interesting test would be to get the bird trimmed out in the cruise - let her settle down (everything balanced), then remove the thrust component by throttling back for a few seconds - my guess is that she will nose-up briefly before settling into a slower than expected glide. Your KR flies 2 degrees nose-down, so maybe the root should be at +1.5 for the best drag profile of the fuselage - and the stab <4 degrees. I wonder how this will change with: a) The newer Ashok wing sections b) A more deliberate airfoil section on the HS - 007) I think an airplane looks really cool in a nose down attitude - like the older Bonanza's - so mine will be rigged 1 degree up from whatever finally comes out here. Take care and enjoy. Steve J _______________________________________ to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
