6.8L rocket 190 psi launch, top flaps, airspeed trigger and flight logging

A beautiful day for a launch!, almost no wind and lots of sunshine. Plan for the launch today was a double test. First a test of the improved autoseal launcher and second a test with top fins that pop out released by an airflap trigger. The fins on top push the center re of pressure (CP) up and destabilize the rocket. Intention is to have a "backslider" like recovery. The launcher platform held out perfectly. Could not see a single drop that leaked out during pressurization. Pressurized the 6.8 liter rocket up to 190 psi (rocket was hydro tested with 200 psi). Launcher released the rocket with a little delay (less than 0.2 sec). Watch the video below to see the rocket launch.

The line you see running from the top down in the left of the picture is a rope / elastic band holding down the airflap before launch.
After the launch you hear the topflaps make a singing sound as the rocket disappears into the sky.
After apogee the rocket starts to tumble, mostly laying flat.
So the airflap must have triggered and the top flaps seem to work. But around half way down the rocket starts a nosedive. Where the flaps to small?, what has happened?. Below you see the measurement results from the altimeter. Speed is calculated as height difference / time. It shows the rocket impacted with about 40 m/sec or 140 km/hr!. Top speed on its way up is around 70 m/sec or 250 km/h

Rocket-simulator for this launch gives an apogee of 206 meter / top speed of 83 m/sec and apogee time of 6.1 sec.(water fill was 1.5 liter
So it looks like about of apogee 20 meter height was lost caused by the singing top flaps. And that they where just to small to destabilize the rocket all the way down.