This document summarizes recent (Fourth quarter 1926) research and development activities relevant to the Air Corps. Article listing: Airplanes: Huff-Daland XHB-1; Huff-Daland LB-5 recommended for procurement; Designs and bids for special observation type airplane; Findings of observation board; Procurement specifications; Thomas-Morse metal wings; Designation of amphibian changed; Thaden detachable metal wing covering; AT-4 and AT-5 airplanes ordered for service test; Airplane brake and wheel development; Airships and balloons: Change in power plant of RS-1 airship proposed; Helium tank car; All-metal airship cars; Armament: Airways flare installation (non-Bowden); Signal pistol and ammunition holders; Internal bomb racks; Gun sight, type C-3; Flexible gun mount, type E-2; Barrel type cross brace; Equipment: Motor vehicle development; Goggles with decentered lenses; Test of Tornblad (Swedish) parachute; Materials: Protection of magnesium alloys; Fatigue of metals; Power plants: Packard series 2A, 3A, and 4A engines; Wright J-5 engines; New carburetors for Packard engines; Supercharger development; Scintilla double magneto; Midget spark plugs; Fire hazard from ignition system; Vibration studies of engine crankshafts; Research and experiment: Resume of Materiel Division serial reports: Torsion tests and study of flutter in single spar panel (S-2649); Wind tunnel tests of six airfoils (S-2700); Design for steel engine mount for resisting vibration (S-2701); Critical loading of members under combined axial and transverse loads (S-2709); Study of torsion in wing framework (S-2712); Determination of power of supercharged engine at altitude from propeller characteristics (S-2723); General discussion of tailplane data from aerodynamic viewpoint (S-2715); Weight and performance study of XLB-2 airplane (S-2720); Test of Clark Y duralumin airfoil (S-2721); Wind tunnel test of N.A.C.A. 81 J airfoil (S-2727); Test of Harm Gun Camera (S-2718); Handbook of instructions for airdrome floodlight, type A-1 (S-2710); Manual for installation and maintenance of induction compass, type A-8 (S-2702); Test of Follmer-Clogg parachutes (S-2728); Performance of Douglas O-2 observation airplane (S-2713); Performance of Curtiss AT-4 pursuit-training airplane (S-2716); Test of water and exhaust heated manifolds on Packard engines (S-2707); New books and documents--Additions to Engineering Division technical files during fourth quarter, 1926: International aeronautics: International; Competitions, records, etc.; Aerial navigation; Instruction, Air Corps Engineering School, California Institute of Technology, Ordnance Dept.; Research; Aircraft--Heavier-than-air: [General]; Albatros; Albert; Armstrong-Whitworth; Avia; Bleindel; Handley-Page; Latecoere; Savoia; Sikorsky; Vasallo; Vickers; Wibault; Wright; Aircraft—Lighter-than-air; Armament; Equipment: [General]; Instruments; Parachutes; Wheels; Fuels and lubricants; Materials: Coatings, Paints, etc.; Fabric; Micarta; Metals; Wood; Photography; Power plants; [General]; Beardmore; Cirrus; Gatti; Model W-1A; Packard; Propellers; Accessions to Materiel Division Technical library;