It sounds to me like you might have a couple movies mixed up. The particle beam shooting at the giant flying monster was from "THE GIANT CLAW" the plane was a B-25--- They had to fire a special isotope from the tail... The flying wing -YB-49- was in "WAR of the WORLDS" and dropped a nuclear bomb on the unsuspecting Martians. Of coarse this did no good and they continued to pillage the Earth until the common cold took out the evil intruders. I suspect that at a later date they were cut into wafer thin slices and studied ! Well, there's your answer!
I haven't seen "The Giant Claw", but I recalled it being panned somewhere for its flying monster and its Plan 9 from Outer Space "quality" special effects. Here it is. LOL!:
[video=youtube;hOj0nXpRqX8]https://www.youtube.com/watch?v=hOj0nXpRqX8[/video]
The entire film:
[video=youtube;_rELLMQuUqY]https://www.youtube.com/watch?v=_rELLMQuUqY[/video]
A low budget one that's not bad is "The Lost Missile" because it is something slightly like what would have been experienced by anyone under the flight path of the supersonic, terrain following, nuclear powered ramjet using an -UNSHIELDED- reactor, the Project Pluto Supersonic Low Altitude Missile - SLAM cruise missile. Gamma ray exposure below its flight path even at speed would supposedly have provided a lethal dose but, hey, it's a doomsday weapon, right?
Testing a flight version was fully realized to be problematic... to say the least:
The SLAM Missile Would Have Been a Flying Chernobyl
The nuclear ramjet was crazy awesome, actually worked andthankfullynever deployed
https://medium.com/war-is-boring/the-slam-missile-would-have-been-a-flying-chernobyl-daa6066850af
In the movie, "The Lost Missile" is an extraterrestrial alien one orbiting the Earth in a high inclination orbit that caused it to gradually pass over every point on Earth, destroying everything it flew over, an interesting and unusual sci-fi concept.:
[video=youtube;eEzkx7gfTeU]https://www.youtube.com/watch?v=eEzkx7gfTeU[/video]
Back to the topic of the thread, here's a list of sci-fi flicks from the 50s that might be useful in finding the specific film:
https://en.wikipedia.org/wiki/List_of_science_fiction_films_of_the_1950s