Larry, I used a set of aircraft scales to do my Static W&B. I made an aluminum plate bolted to the main gear leg with notches so I could adjust the location of the main axels forward 1/2" at a time until I got 15% the total aircraft and pilot weight on the nose wheel. All of this is with the longerons level. The 12# battery was on the firewall in the engine compartment. Relocating it behind the seat improved the aerodynamic CG. My goal was to be at 25% chord or 12" aft of the wing leading edge. My plans indicate that the firewall is at f.s. 30".
Ryan N81BP KR-2 Text 858-229-4875 -----Original Message----- From: Flesner [mailto:fles...@frontier.com] Sent: Tuesday, August 24, 2021 4:31 PM To: krnet@list.krnet.org Subject: KR>Re: KR flight characteristics On 8/24/2021 5:14 PM, Ryan wrote: > My standard KR2 with Tri-Gear was pitch sensitive at 25% chord. I moved the > 12# battery behind the seatback to get 22% chord and now it is not pitch > sensitive with 1 person aboard. I have flown with 160# of ballast with a > similar result. > Text me if you are in my area for some stick time. Copilot should be under > 200#. > Ryan +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Ryan, Thanks for your post. With your permission I will attempt to add some clarity to what you posted. The plans call for a CG range of 15%-35% of chord, 8-16 inches aft of the wing center section lead edge. You stated you were at 25% (12") and "move the battery behind behind the back seat". We can only assume you meant "from behind the back set forward" and that put you at 22% (10.56"). Moving the CG forward would certainly improve pitch stability but it seems 1.44" is not significant enough to make a major improvement. Can you give us an idea of how accurately your scales were and how close your measurements were? What was the distance forward you moved the battery? Is it again pitch sensitive with a passenger? It seems a passenger would have moved the CG back at least to the 25% where it was once pitch sensitive. Don't take my questions as disbelief in your results but as a means to determine accuracy so that others may benefit from your findings. I know it has been stated hundreds of times but I'll repeat once more. For standard KR2's, stay out of the last 2" of the published CG range. Ryan and others. If you have info to share, my all means do so. Just try to be as thorough and as detailed as possible. We'd like to hear from you. For those attending the Gathering I'm scheduled to give a Power Point presentation on W&B. We'll cover "what it is", "all the factors" , "why we care", and "how to determine the CG on YOUR airplane". How many more days? Larry Flesner ________________________________ -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html -Change list delivery options at https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board -Search recent KRnet Archives at https://list.krnet.org/empathy/list/krnet.list.krnet.org/ -Search John Bouyea's decades of archive at https://www.mail-archive.com/krnet@list.krnet.org/
