These are the programs I remember best, but I'll be happy to add your favorites if you'll just contact me or leave a message in the Message Forum. At this point we've got Tom Corbett, Captain Video, and Sky King.

Tom Corbett, Space Cadet

The Tom Corbett series was inspired by Robert Heinlein's novel Space Cadet, which was published in 1948. Tom Corbett—Space Cadet first appeared on television in 1950. The plots were initially largely based on scripts written for an unpublished newspaper comic strip named Tom Ranger, Space Cadet. Books, a newspaper comic strip, and comic books followed.

The television show ran on various networks until 1955. 

You can watch several complete episodes of the program on YouTube, but only if you have a relatively high tolerance for fuzzy pictures. Here's a clip of the show's opening (and a sample of the video quality):

 

Captain Video

The Captain Video series aired between 1949 and 1955. A separate 30-minute spinoff series called The Secret Files of Captain Video aired Saturday mornings, alternating with Tom Corbett, between September 1953 and May 1954.

As Wikipedia puts it, the Video Rangers, led by Captain Video, operated from a secret mountaintop base wearing uniforms that resembled U.S. Army surplus with lightning bolts sewn on.

It's a tribute to the show's creative staff that the series lasted as long as it did considering its crude, low-budget quality. The show was done live on the cash-strapped DuMont television network. Its prop budget was just $25 for five to six 30-minute episodes per week  (roughly equivalent to $250 today).

Until 1953, Captain Video's live adventures occupied only 20 minutes of each day's 30-minute program time. To fill out the rest and save money, about 10 minutes into each episode a "Video Ranger communication officer" popped in to show about seven minutes of old cowboy movies, described by officer "Ranger Rogers" as the adventures of Captain Video's "undercover agents" on earth.

The show's theme song was Richard Wagner's "Overture to The Flying Dutchman." Captain Video's "mountaintop headquarters" was a drawing on a 4' x 4' piece of cardboard on an easel.

Despite the show's obvious shortcomings, it attracted some first-rate writing talent, including Arthur C. Clarke and Isaac Asimov, and was popular with both children and adults throughout its six-year run.

Although most of the original kinescope recordings of the show were destroyed (following common studio practice) these movie theater shorts, Captain Video: Master of the Stratosphere (1951) part 1, and part 2, give us a feel for the television originals.

On Jackie Gleason's Honeymooners program, best friend and neighbor Ed Norton did a turn as a volunteer Video Ranger:

 

Sky King

Sky King represented a compromise of sorts between cowboys of the past and heroes of the future: he piloted a plane rather than a horse (though he was an Arizona rancher) or a rocket ship and solved problems in the present day.

The television program began in 1946 and was based on a story by Roy Winsor. The television series debuted in 1951 and ran until 1959.

The plots would often parallel such adventure series as the Adventures of Superman, with subordinate characters often finding themselves in dire peril with the hero rescuing them in the nick of time. 

Though the plot lines were simplistic and the acting often wooden, the writing was generally well above average. Villains and other characters were usually depicted as intelligent and believable, and many pilots, including American astronauts, grew up watching Sky King and named him as an influence.

Many episodes are available on YouTube. This is just one example.

The opening and closing credits for the show were remarkable feats of photography. Here's the opening:

And here's the closing: