A US National Defense Research Committee report on the history of the project explains in a footnote that the name "Yehudi" in then-contemporary slang meant "the little man who wasn't there".

Colonna continued the gag on later shows without Menuhin, turning "Yehudi" into a widely understood late 1930s slang reference for a mysteriously absent person.

[3] A Canadian professor, Edmund Godfrey Burr, had serendipitously stumbled upon the principle when he saw an aircraft coming in to land over snow suddenly vanish.

[3] An equivalent active camouflage strategy, known to zoologists as counter-illumination, is used by many marine organisms, including fish, shrimps, and cephalopods such as the midwater squid, Abralia veranyi.

They were further told that while "floodlighting"[1] the aircraft (in the manner of diffused lighting camouflage for ships) could in theory make it bright enough to match its background, that would require an impossibly large amount of electrical power: but a less power-hungry option was available, namely to use forward-facing lights, and to require the aircraft to fly within 3 degrees of the line directly towards the submarine, so that only its counter-illuminated front would face the enemy.

Since making the beams bright enough at such a wide angle was impracticable, pilots were instructed to keep the nose pointed directly towards the target at all times, resulting in a curving approach path.

During a test in the winter of 1943, selecting a day when the visibility was above 2 miles (3.2 km) and the wind not so strong as to destroy the prototype, the observers could clearly see the 1 inch (2.5 cm) thick cables used to hold up the model, but the silhouette itself was "completely invisible" with the lamps correctly adjusted.

[3] In 1945 a Grumman Avenger with Yehudi lights got within 3,000 yards (2,700 m) of a ship before being sighted, when under the same conditions an uncamouflaged plane was detected at a range of about 12 miles (19 km).

It was noted at the time that this would force the enemy either to give up radar silence, making submarines easy to locate but harder to approach, or for observers to use binoculars continually.

The Have Blue prototype was disruptively camouflaged to disguise its shape from casual onlookers, as well as being constructed of angled facets to reduce its radar cross-section.