I don't see where this equation came from since I can't see a link to the source, but whatever. For such important formulas, I always include the sources.
With the addition of the Weyl vector potential theory, the formula for the Biefeld-Brown effect can now be derived:
https://arxiv.org/pdf/gr-qc/0507082.pdf
Weyl electrovacuum solutions and gauge invariance
Dr. B.V. Ivanov
https://arxiv.org/pdf/gr-qc/0502047.pdf
On the gravitational field induced by static electromagnetic sources
Dr. B.V Ivanov
Using your numbers, for a plane at 9km, with a voltage of 20MV:
For some reason it's all in CGS units...
d=9e5 [cm]Brilliant.
d refers to the distance between the PLATES OF THE CAPACITOR.
And there are some 300 capacitors, if not more, on board the B-2 bomber (if they are not using the wings themselves as some huge capacitors to start with).
What we need is the dielectric constant for those capacitors, the distance between the plates, and the voltage applied for a single capacitor (that is, we also need to know the surface area of the plate of the capacitor).
So, any estimate must use at least these figures: d = 0.5 cm, e = 10,000 (if not more), surface area for a 45 cm diameter of the plate, and the voltage at least 60 Kv per capacitor.
To use the formula for the entire aircraft, in case just a single very large capacitor is utilized, we'd need to know how the 20,000,000 volts are distributed across the wings, the distance chosen between the upper and lower plate of the capacitor, the entire surface area underneath the wings used for the capacitor, the dielectric being used.