A piece of artwork (almost certainly a negative, based on the shading and the national insignia) depicting the Kaman K-16 deflected slipstream tiltwing VTOL flying boat project. The K-16 was actually built in 1959, but never flew and was cancelled in 1962.
The airframe somehow managed to survive and is on display at the New England Air Museum in Windsor Locks, Connecticut. I visited there a couple times years ago and took a number of photos, posted HERE (2001 visit) and HERE (2007 visit). The full rez scan of the artwork has been made available at 300 DPI to all $4/month patrons/subscribers in the 2021-05 APR Extras folder at Dropbox. If you would like to help fund the acquisition and preservation of such things, along with getting high quality scans for yourself, please consider signing on either for the APR Patreon or the APR Monthly Historical Documents Program.
