The downward spike in the altitude data is the ejection charge pressurizing where the altimeter is (higher pressure, lower altitude). The rest is the kind of noise you get when the altimeter is out in the breeze and flopping around. Youāre not going to block the pressure sensor completely unless you manage to directly cover the tiny hole on the pressure sensor itself.
You posted the flight twice to the online logā¦.but with no description or other data.
Hereās the online version, with the acceleration trace squeezed to line up with the barometric trace. You can see the big acceleration spike from the ejection charge and that it limes up with the dip in the altitude trace.
View attachment 479799
Even here itās clear the delay isnāt long enough. I have no idea how Steve Krystal got one to over twice this high to set that 1/8A NAR record. I guess Iām just going to have to ask him.