For the rotorcraft historian or modeler, this photograph reveals Bell 47/H-13 center-frame and box-beam engineering test photograph. The reverse handwritten note reads “Bell 47/H13 Centerframe and Box Beam 1950.” The image shows the tubular center frame, cooling fan, drivetrain-area components and an instrumented box-beam/fixture inside a laboratory test structure.
The Bell 47/H-13 center frame carried the helicopter’s engine, transmission, rotor mast, landing gear and cabin attachment loads. Testing this central structure was critical because it concentrated many of the highest mechanical and flight loads in a compact welded-tube assembly. The visible cooling fan and structural members provide an unusually intimate view of the Bell 47’s internal architecture. The 1950 date places the image during rapid expansion of military H-13 and commercial Model 47 production.
From the Jeffrey C. Evans Helicopter Archive Estate. Jeffrey C. Evans (1945–2025) was a respected helicopter historian, researcher, photographer, and archive collector whose work helped preserve important rotorcraft history. He was a longtime member of the Vertical Flight Society and Vertical Aviation International, and he co-authored The Bell 47 Helicopter Story. This piece was preserved within his California aviation archive, giving it meaningful collector provenance and a direct connection to decades of helicopter research.
Good archive condition with clear mechanical detail. Light surface wear, handling marks and minor edge/corner wear may be present. The reverse bears handwritten identification. No major tear is visible. Review all images. Please review all photographs carefully for the exact surface, edges, reverse, and included details.
| Subject | Bell 47/H-13 center-frame and box-beam engineering test photograph |
| Date / Era | 1950 |
| Format | Black-and-white archive photograph / photographic image |
| Size | 8 x 10 inches |
| Identification | Confirmed By Reverse Caption; Precise Test Purpose Unconfirmed |
| Provenance | Jeffrey C. Evans Helicopter Archive Estate |
| Custom SKU | PHO-FLD64-YU2Q |
Free tracked shipping is included. Packed carefully with firm backing so the photograph travels safely to your collection.
The photos show the exact archive piece offered, including markings, edges, and visible wear.
Add this detailed internal-structure reference to your Bell 47 or H-13 research library.
A strong addition for Bell helicopter collectors, aviation historians, modelers, and technical-image archives.