How does a plane hold a beam for 30 seconds? Planes don't hover. Also that's 83 hours to destroy 10,000 homes. Too long to be feasible.
If the beam is wide enough to melt more than one wheel at once pthen they would need much more than that 2.5MW generator, beyond the payload capacity of any airplane.
Your welding rig appies current directly to the metal. The DEW requires RF or high frequencies like x-rays to transfer the energy and I assumed no losses. Welding hs no losses. Beams have losses.
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The beam is easily aimed with two swivel heads.
They are likely held constant digitally.
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X-ray lasers have far less losses than wire cables.
(but everything has losses)
My infra red laser EDMs shoot miles with hundredths of a watt of power.