Mark,
First of all, CONGRATULATION ON THE 178 PILOT WEIGHT !!!! How did you accomplish that?
If 903 lbs with fuel is correct, your Empty weight looks reasonable for what is being built today. I would be inclined to verify each "station" measure. If they are correct, and I'm guessing they are, and the math is correct, I'd verify the KR level to obtain the weights and then *check the incidence of the horizontal stabilizer with aircraft level.* I can't imagine with proper c.g. as you have computed and correct H.S. incidence that the airplane pitched up like it did. My only other thought is the weight on the nose wheel. Seems a bit heavy. Did that necessitate more back stick to rotate and at the second of rotation, when the wing started flying, you had excessive back stick that caused the nose to pitch up abruptly? We're talking a 2 second interval here. Does the KR set near nose level in flying weight. If the KR sets nose low as it accelerates the wing has little if any angle of attack. That would also require more back stick to rotate and if the wing goes from very little lift to flying lift in a matter of seconds, a severe and sudden nose up could occur. All of this is of course, speculation. You've got enough KR time to know what you're doing. If all else is correct I'd start with a very slight back stick to start the takeoff roll to soften the rotation and see what happens.
Bottom line. If *all* your numbers are correct, I don't think you have a C.G. problem. Did you change the gear geometry at all? Does the airplane start to feel light at rotation or do you have to initiate rotation with back stick. The airplane should be telling you what its doing.
Of the several homebuilts I've made first flights on, two of them jumped off before I anticipated and needed a one or two second recovery to keep from breaking things. Those were the Zenith 701 with the 130 hp auto engine and a Murphy Rebel with an 0-320 Lycoming. My KR was the nicest flying airplane I've ever flown from first liftoff till it found a new home 800 hours and 20 years later. Another "first flight" nice flier was the Zenith 601 with the Harley Davidson engine with a motorcycle throttle on the Y stick.
You'll get it figured out. Good luck...................................... Larry Flesner +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ On 5/20/2026 4:29 PM, Adam Deem via KRnet wrote:
There, I fixed it for your fuel tank station. Didn't affect the result too much, and doesn't explain why you experienced what you did. I hope you figure it out. If I can help, let me know.Adam Date: 5/20/2026 A/C Type: KR2S Serial #: Registration #: N771MJ Owner Name: Mark Jones Address: Datum: Front edge of prop crush plate Allowable CG: 54.5"-60.5" Max Weight: EMPTY WEIGHT & CG Description Station Weight Moment Left Wheel 67.5 319.0 21532.5 Right Wheel 67.5 325.0 21937.5 Nosewheel 21.5 259.0 5568.5 Empty Wt/CG 54.31 903.0 49038.5 ADJUSTMENTS Description Station Weight Moment Full Fuel 64.0 -145.2 -9292.8 0.0 0.0 0.0 0.0 Adjusted Weight/CG 52.45 757.8 39745.7 OOPS FLIGHT CG 1/4 TANKS Description Station Weight Moment Empty Wt 52.4 757.8 39745.7 Pilot 65.0 178.0 11570.0 Passenger 65.0 0.0 0.0 Fuel 64.0 36.0 2304.0 Baggage 100.0 0.0 0.0 Loaded Wt/CG 55.2 971.8 53619.7 CG WITH PILOT & FULL TANKS Description Station Weight Moment Empty Wt 52.4 757.8 39745.7 Pilot 65.0 178.0 11570.0 Passenger 65.0 0.0 0.0 Fuel 64.0 145.2 9292.8 Baggage 100.0 0.0 0.0 Loaded Wt/CG 56.1 1081.0 60608.5 NOTES:CG range is listed as 8-16" aft of stub wing leading edge by Rand Robinson build manual, however flight testing has shown operation in the aft 2" is undesireable due to insufficient stability.The range listed on this sheet excludes the aft 2" as recommended.
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