I can't guarantee that all of this information is related to the same person, but here's what I dug up.
From NARA's Vietnam casualty list:
Charles Donald Roby
Birth date: 25 Sep 1928
Department of the Air Force, Regular
Service Occupation: Pilot, Tactical Fighter F-110 (USAF)
Date of death or casualty: 03/21/1979
Unit: 497 TAC FTR SQ
Home of Record: Iowa Park, TX
From the Social security Death Index:
Social Security Death Index:
Charles Roby, born 25 Sep 1928, died Mar 1967.SSN issued in Texas (Before 1951).SSN: 458-34-1715
This is the only Charles Roby of the appropriate age in Texas.There were several others in other places.
1930 United States Federal Census > Texas > Young > Precinct 4 > District 10 > Page 9B
Dwelling 165/Family 176
John C. Roby, head, rents ($10/month).owns a radio.white, 36, married, age 28 at first marriage, reads, writes, he and parents b OK, foreman at oil field, Veteran of World War I
Daisy M Roby, wife, white, 31, married, age 23 at first marriage, reads, writes, b TX, father b Alabama, mother b TN
Harold E., son, white, 7, attends school, b TX
James W., son, white, 2 yrs 9 months, b TX
Charles B, son white 1 yr 9 months, b TX
From World War I draft registrations:
John Charles Roby, age 23.Residence: Scroggin, TX.Born 9 Nov 1893 in Oklahoma.Natural-born citizen.Farmer.Single, Caucasian.Medium height, medium build, blue eyes, light hair, not balding.
Registered 5 Jun 1917 in Franklin County, TX (Precint 7). Form 55., No. 38.
Texas Death Index:
Daisy Mae Roby, died 7 Jul 1992 in Bexar County, TX (San Antonio area)
James W Roby, d 13 Nov 1972 in Harris County, TX.Married
For your next step, I would advise you to order the Social security Application for the SSN listed above.These usually list the names of the parents of the deceased, so it would confirm or disprove the 1930 census entry I found for you.
You can also try to order his military records -- they should list his next of kin.I'm not sure how easy that is if you can't prove descent, but you can certainly try.