This is the description of the image which is written in HTML and may contain links, images, … .
The Hiller OH-23 Raven was a three-place, light observation helicopter based on the Hiller Model 360. The Model 360 was designated by the company as the UH-12, which was first flown in 1948. Wikipedia
By U.S. Army – U.S. Army photo from the official U.S. Department of the Army publication Vietnam Studies – Airmobility 1961-1971. Washington D.C. 1989  photo , Public Domain, https://commons.wikimedia.org/w/index.php?curid=191747