Preliminary Specifications for the Lockheed Model 49 Long-Range S ub-Stratosphere Transport Airplanes. Confidential Report No. 1536 , Sept 13, 1939. [Original report; not a photocopy or pdf]

Burbank: Lockheed Aircraft Corporation. Very good. 1939. Title Page: “Preliminary Detail Specification for the Lockheed ‘49’ [Model 49-47] Submitted Under Information for Approval o f Design - [Copy No] 14” ##### . in custom two-hole binder. 30 pp., consisting of 23 mimeographed pages of specifications, printed one side only and 7 photostatic plan sheets including 2 foldout plans of the cabin layout -- plu s From the foreword: “This detailed specification overs the gen eral requirements and design of the Lockheed ‘49’, a long ran ge, substratosphere, day or night transport airplane. …Upon th e negotiation of a contract for this airplane, a revised detail s pecification will be prepared describing as nearly as possible th e proposed airplane.” Specs prepared by Peter A. Beck and appr oved by Hall L. Hibbard, one of the plane’s design engineers, w hose mimeographed signatures are present. Condition: mimeographed pages are pristine; clean, bright, with no tears or marks. Cover s are very good with rubbed edges, some light rusting to the meta l fastener. ##### . ee years later, in January 1943, but commandeered as a military a ircraft (the C-69 military transport). It remained in production through 1946 when it entered civilian use with TWA. In modified iterations the Lockheed “Constellation” became the primary ai rliner used by TWA, PanAm, Western Airlines and other major carri ers for nearly three decades. ##### . driven, four-engine airliner with a triple-tail design and dolphi n-shaped fuselage. It introduced several technological advancemen ts such as electric de-icing, hydraulic assisted controls, revers ible pitch propellers and pressurization, which allowed the plane to fly above the clouds. This enabled large numbers of commercia l passengers to fly well above most bad weather for the first tim e, thus significantly improving the general safety and ease of ai r-travel. .