Since she doesnt have an official height, we'll use this for scaling
Nonon is 1.36 m tall
1.36 / 112 = .0121 m/px
.0121 x 762 = 9.2202 m
.0121 x 1049 = 12.6929 m
12.6929 / 275 = 0.046156 m/px
0.046156 x 661 = 30.509116 m
0.046156 x 363 = 16.754628 / 2 = 8.377314 m
Plugging this into a cone gives us 2242.17 m^3
It has some hollowness to it but its mostly a solid block, so 25% hollowness should be okay. That gives us a volume of 1681.6275 m^3 for the body.
Next the fins. There are three of them so the result will be tripled.
0.046156 x 109 = 5.031004 / 2 = 2.515502 m
0.046156 x 257 = 11.862092 m
Plugging this into a cone gives us 78.6 m^3 x 3 = 235.8 m^3
Now for the part to remove.
0.046156 x 378 = 17.446968 / 2 = 8.723484 m
0.046156 x 147 = 6.784932 / 2 = 3.392466 m
0.046156 x 71 = 3.277076 m
Plugging this into an ellipsoid calculator gives us 406.24 m^3 / 2 (As its only half) gives us 203.12 m^3
So 2242.17 + 235.8 - 203.12 = 2274.85 m^3
Now, since we use silk as a density for Life Fibers, we'll use 1340 kg/m^3.
2274.85 x 1340 = 3048299 kg, Class M
First off, a nice little upgrade to Ryuko seeing as she pulled this thing out of the sky and swung it around.
Now then, for the KE of this thing.
As seen here, the Academy itself goes beyond Cumulus clouds but still has Cirrus clouds well above it. That would put Honnouji Academy at ~1000 meters high. Cirrus clouds appear at an average height of 12 kilometers, ot 12000 meters.
As seen here, it takes Nonon 2.5 seconds to fly from the cloud layer she and Ryuko were fighting in to the tower Satsuki was standing on. So she crossed 11000 meters in 2.5 seconds (I'd get a more precise measurement with a frame by frame but the only video i can find of this has that scene cut out).
11000 / 2.5 = 4400 m/s
KE = 1/2MxV^2
= 1/2(3048299)x(4400)^2
= 1524149.5 x 19360000
= 2.9507534e+13 Joules, 7 Kilotons of TNT, Town level
Ladies and gentlemen we have consistency.