Barry, You are correct and keep in mind that on the stock KR-2S(with GPAS 2180) we did increase the H. Stabilizer by 15% already. Flight test with the original H. Stabilizer showed that with little fuel(header tank fwd of CG) an 2 crew aboard the KR did not return to trim Speed.
With the increase I have excellent return speeds flown solo (dynamic stability returns are less than 15 seconds). However the KR is still reluctant to return to a trim speed with 2 crew and minimum fuel. It shows that the Chris Heintz Stability line is wider (more an area) than just a line, as the CG moves back the tendency to depart from trim speed increases. This stability issue is of concern to our authority, but we do have a positive manouver stability from about 0,15kg control force at 1,3g we go up to about 0,6kg at 2,5g (its very little but still positive....). Christian OE-VPD (after 67 flight hours and 350 landings, applied for final certification...) -----Original Message----- Christian, great spreadsheet and thanks for sharing.The spreadsheet and the link http://exp-aircraft.com/library/heintz/stabilty.html (found in the spreadsheet) enable us to more accurately calculate the CofG ranges and determine the stable CofG range.In my opinion, using the calculations from the above link, if you increase the main wing area you must increase your horizontal stabilizer wing area OR move your horizontal stabilizer further back from the main wing. ELSE you will lessen the CofG range. (I was thinking of adding longer wing tips to decrease my stall speed, but not now without more investigation)I'll go to airport this weekend and measure my wings' accurately so I can apply the calculations to see what my CofG range is. This, as I see it, only gives me my rear CofG limit, or am I missing something. How do we calculate the forward CofG limit? Trial and error, too much forward CofG and we can't round out for landing, expensive and painful way to learn :-)The first of our monsoonal tropical rain depressions is here, so no flying for the last 2 days and the next few days :-(Time to finish of some of the things left to after first flight.RegardsBarry KruyssenCairns, AustraliaRAA 19-3873 [email protected]http://www.users.bigpond.com/kr2/kr2.htm ----- Original Message ----- From: Mark Langford See message below, and link to Christian's spreadsheet at http://www.krnet.org/misc/stability_kr-2s.xls . Any questions should be probably be directed at Christian, and through KRnet would be fine, since others might have the same questions. ----- Original Message ----- From: "Kogelmann Christian - OS TDA" <[email protected]> Subject: RE: KR> AS 504X CofG I have an MS Excel File to determine the C/G (RAF48) and the stability of my airplane. I could not put it on my web page yet so I thought you might want to publish it. I had to do this for our authorities and of course they moved the allowable aft C/G forward..... In the File: HLW = Horizontal Stabilizer (including Elevator) And other German Expressions should be self explanatory (if not I will prepare a full english version) I have an input page for fuel and crew and based on the input the C/G moves in the chart. We did increase our HLW but did not manage to move the stability line out of the c/g range, there the authority will limit us at 29,5% C/G. If you think it is useful, you are welcome to publish it._______________________________________Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jspto UNsubscribe from KRnet, send a message to [email protected] see other KRnet info at http://www.krnet.org/info.html
