You don't feed nearly entire vehicles into a furnace to melt them down. You feed them through a shredder to make metal bits first. The metal bits get fed into a furnace.
You really made me question this as I have no idea about it's validity. However, that was an enjoyable poke around the web and I came back with this.
A study was conducted to determine the most cost effective way to dispose of planes; it was determined that too many man-hours were required to dismantle planes for parts, and the cost for storage areas for the parts was too high.
So the method of "salvage and melt" was adopted. Main components such as engines, armament, instruments and radios were removed from each plane. The remainder of the aircraft was cut into pieces, and pushed in a large furnace, or smelter. Aluminum was the prime metal sought after, melted and poured into ingots for sale and shipping.
https://www.airplaneboneyards.com/post-wwii-military-airplane-boneyards.htm
This still does seem like an odd method, but I don't know anything about smelting airplanes lol. But that source does correlate with the removal of main components. And the other pics on that website are of substantially larger airplanes. So I can't really say for certain. However I do suspect that this picture is somewhat suspect as I can only really find it on an unverified tumblr post. And there seems to be some sort of filter on it.
What makes you say that?