My wings began flapping - scary - what was it?

[wildirishtime]

So here's the scenario, looking for feedback on what
I experienced:

Model 3, 90hours total time, I have 50 of those since I purchased it.
9am in Oregon
winds @ 800ft AGL: 10-15mph from the north.
Direction flying: South
Airspeed Indicated: 75mph
Thermals: Moderate to Heavy, it's a 100degree day now.
Engine: 582
RPM: 5000ish
Load: 950lbs gross

While minding my own business the wings suddenly
began oscillating up and down, both sides it appeared. Lasted
3-4 seconds. I was about a mile south of some rolling hills.

I pulled the power to 4000, pulled the nose back a touch to drop
it below 70mph... and waited. It stopped. Full inpsection shows
NOTHING loose etc... remainder of flight was normal (but quite
gusty, bumpy, and not much fun due to weather).

So please avoid wild speculations (I can do that on my own haha!)
if you've had this happen or KNOW what this was from experience
preferably in a model3 please let me know... just wanting to double
check this isn't a known issue of any kind and was truely just the
airflow/thermals that prevailed.

Thanks in advance!
~Wild

[cap01]

i have the long wings on my model IV and they will move up and down at the tips when i get into choppy air . it is a little unnerving at first , but you get used to it . ive been in some pretty rough air and they have really been flapping but nothing has happened .

[catz631]

Chuck,
I venture to say this is normal movement in the wing. My model 4 wings do that also. I was a little supprised in the beginning when I saw that much movement but it dosn't bother me at all now. Your eyes are almost level with the bottom of the wing and any flex in the wing you will see right away. The wings are just a couple of aluminum pipes with non rigid covering (unlike a metal aircraft) so really they should be expected to flex. Bottom line is there have been no inflight structural breakups of the Kitfox (see new Kitplanes mag) so I think you have nothing to worry about.
Flutter,on the other hand,is much more violent and a whole different ball game but that's not what it sounds like from your discription.
Talk about wing flex the B-737 I used to fly would flap its wings all over the place in rough air !
Dick

[Mnflyer]

HI dido on the previous posts, as Dick posted the main spars a alum tubes very strong and flexible, I've seen the flex on my plane also does get your attention the first few times.

[wildirishtime]

Well I'm not sure where "flex" ends and "flutter" begins. I've seen the wings flex a little, and that's ok.... but it was vibrating my control stick in my hand pretty hard - had to hold on pretty tight - It was the wings, not the flaperons.

It was harsh enough I thought I had a prop blade change pitch.... does that still match with 'flex' or would someone call that 'flutter'? and if it's flutter, was that still acceptible behavior for the model 3?

[cap01]

i have never felt anything in the stick that felt like a flutter so im just seeing flexing . they can be a wild ride in rough air .

[Dave F]

So here's the scenario, looking for feedback on what
I experienced:

Model 3, 90hours total time, I have 50 of those since I purchased it.
9am in Oregon
winds @ 800ft AGL: 10-15mph from the north.
Direction flying: South
Airspeed Indicated: 75mph
Thermals: Moderate to Heavy, it's a 100degree day now.
Engine: 582
RPM: 5000ish
Load: 950lbs gross

While minding my own business the wings suddenly
began oscillating up and down, both sides it appeared. Lasted
3-4 seconds. I was about a mile south of some rolling hills.

I pulled the power to 4000, pulled the nose back a touch to drop
it below 70mph... and waited. It stopped. Full inpsection shows
NOTHING loose etc... remainder of flight was normal (but quite
gusty, bumpy, and not much fun due to weather).

So please avoid wild speculations (I can do that on my own haha!)
if you've had this happen or KNOW what this was from experience
preferably in a model3 please let me know... just wanting to double
check this isn't a known issue of any kind and was truely just the
airflow/thermals that prevailed.

Thanks in advance!
~Wild

>>... just wanting to double
check this isn't a known issue of any kind and was truely just the
airflow/thermals that prevailed.<<


I am going to agree that is sounds like wing flexing .

Cheers