Pitch Stability

[TroyBranch]

I can't do a whole lot of flight testing until I get the engine broke in but one item I always check is the over all stability in cruise. I trim the airplane out and have it fly on its own. Add a 1 pound of pressure on the stick and see what happens. To my surprised this was my results. Could others comment if their cub does the same?

Trimmed for high cruise (115 mph indicated)
One pound aft on the stick for a half second or so and release.
Plane pitches up and pitches increased, g load increases on its own. A substantial pitch up.
Plane slows down and the nose will slowly go through the horizon.
The nose accelerates through the horizon with no tendency to pitch up after passing the original trim speed.
You have to recover or there will be a soon sudden stop at ground level

Same set up but push forward.
Plane continues past trim speed with no pitch recovery of it's own.

Pull throttle by a 100rpm or so, plane pitches down and continues to pitch down after going through trim speed.

What I was expecting was for the plane to do was isolate a few times and recover. Not a chance. This no where near and aerobatic airplane and really though it would be very dynamically pitch stable. I sure isn't at higher cruise speeds at least.

I plan to try the same at lower speeds to see how it reacts.

Is this typical for a cub because of the trim able stab. I have very little cub experience and did not expect this test to have this outcome.

[TroyBranch]

So this morning I went out did the same test. It was blowing 20kts on the ground so I knew it was not going to be smooth for working the engine. I trimmed and set power for 95 indicated which is just over 100mph true at altitude. It recovered as I first expected it should. Once past trimmed speed buy about 20mph it would start nosing up. So clearly the cub does not like 130 mph true. This all makes sense though. You need to be quite trimmed down at those speeds and everything is too neutral per say. This is giving the instability in both directions. Not sure how it will be loaded up, we will learn that soon enough.