Weird Takeoff move...

19 Mar 2024 01:30 #1 by Brooks McNew
Replied by Brooks McNew on topic Weird Takeoff move...
The fact that the left vertical stabilizer is slightly higher while the left wing is slightly lower is interesting, but I wouldn't draw any final conclusions about the airframe if those measurements were made while resting on the landing gear.

I'd like to really level the aircraft. Get a 4ft level and a 2ft level. Get it level along one windowsill and across the two windowsills. You can roll the wheels onto small blocks or scraps of sheet metal, even stacks of printer paper. Just don't use corrugated cardboard because it'll compress while you're trying to work. You can fine tune (or maybe accomplish the whole levelling task) by adjusting tire pressure too.

Once you're truly level, get measurements at corresponding points of the wing tip, trailing edge, leading edge, and similar points on the horizontal stabilizer, elevator trailing edge, etc. Then you'll have a better idea if something is twisted or bent.

I feel sympathy here because my coupe came with a tail strike preinstalled so my tail cone is ever so slightly tweaked upwards, with a scuffed stinger & rudder bottoms. It's not a problem for my A&P but I just... know it's there. The only part I had to replace was the tail tiedown ring. It was bent and the tiny bracket it screws into needed a correspondingly teeny little doubler plate to make us happy.

The good news is, if I ever do a tail strike I won't be the first one to scuff perfect metal.
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10 Mar 2024 01:28 #2 by James Davis
Replied by James Davis on topic Weird Takeoff move...
Just to mention, nose sway to the left and drop of the right wing is very sudden and rapidly happens right after nose wheel leaves the runway.

But after the correction plane climbs at 80-85 mph like a bat out of hell...

Mystery ????

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10 Mar 2024 01:24 - 19 Mar 2024 02:14 #3 by James Davis
Weird Takeoff move... was created by James Davis
My newly purchased 415-C with Alon tail (STC) showing a weird characteristic ONLY during the takeoff...
This weird thing happens ONLY as soon as plane leaves the runway for the next 10-15 seconds and then it flies ok without any similar awkward move and lands ok too...
This is what's happening...

Conditions: Calm Winds, Airport Altitude 230', 1 pilot at 240 lbs and 21-22 gal/fuel, no passenger or
luggage of any kind.

Propellor McCauley 7148,  Static RPM 2200

- I hit the throttle to full and begin my takeoff roll,
- 30, 40, 50, 60 mph, plane follows the centerline with minimal effort
-at 60 mph I apply back pressure to yoke and at 65 we leave the ground...


Plane's nose moves to the left as if somebory was pushing the nose to that direction WHILE the right wing drops a foot or two momentarily.
Then I respond with a little right turn input on the yoke first then a little left input to level the wings and then steer the plane as I should and climb at 80-85mph.
Rest of the flight is uneventful and it's smooth actually. Level flight is straight and fast enough 100-105mph.
Descent is controlled and stable and landing is ok too...

Ferry pilot noticed first and we were thinking it may be due to crosswind. But it is consistently the same thing happening even when it is calm or no matter which side the crosswind is blowing from.

Plane was a little uneven when I measured. Left vertical stabilizer top was 74 3/8" and the right one was at 74 1/4"
But at the wingtips right wingtip is 1 1/4" higher than the left one...

Now within the light of all this info, does anybody have an idea what may cause this sudden nose sway to the lift at the same time dropping the right wing tendency????
Like I mentioned earlier, since the rest of the climb, level flight, landing is all perfectly acceptable without any weird movement like this one, what may be the cause of this...
Friends and I think if there was a certain setup problem it will show itself or effect the flight in other stages of flight too and NOT only during the takeoff for a few seconds... Right???
Any ideas? Any similar experiences? 
Last edit: 19 Mar 2024 02:14 by James Davis.

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