4 YEARS OF AERONAUTICAL RESEARCH — ^HUNSAKER 259 



aircraft) were completed in 1931. The designer of the $900,000 "full- 

 scale" wind tunnel (then the world's largest) was Smith J. DeFrance, 

 who became director of the Committee's second research center, at 

 Moffett Field, Calif., when it was established in 1941. 



A somewhat later "depression baby" was the 500-mph. 8-foot wind 

 tunnel. For some time after its completion in 1936, it was known, 

 somewhat optimistically, as the "full-speed wind tunnel." Other novel 

 research equipment constructed at Langley in these years included a 

 free-spinning wind tunnel and a refrigerated wind tunnel (for study 

 of icing problems) . 



In this depression period NACA engineers first disclosed the ability 

 to use air more than once. Soon after the variable- density tunnel was 

 rebuilt following a fire in 1927, it was suggested that some use should 

 be made of the air released each time the tunnel was returned to atmos- 

 pheric pressure. ^¥hJ not discharge the pressurized air through an 

 appropriate nozzle and thus obtain a really high-speed air stream? 

 The result was a blow-down device, with a 12-inch test section in which 

 aerodynamic phenomena could be studied at speeds almost that of 

 sound (about 760 mph. at 60° F.). 



Thus far, the discussion of research by the NACA has been largely 

 concerned with aerodynamics where the greatest effort was made. 

 Nevertheless there was fruitful work on powerplants, loads, and struc- 

 tures, which will be noted later. In retrospect, one marvels that so 

 much could be accomplished. At the beginning of 1930, for example, 

 the total employment at the Langley Laboratory was only 181. 



By the mid-thirties, the work of the NACA had become interna- 

 tionally known and respected. Somewhat earlier the British journal 

 Aircraft Engineering had commented about the Committee: "They 

 were the first to establish, and indeed to visualize, a variable-density 

 tunnel ; they have led again with the construction of the 20-foot pro- 

 peller research tunnel ; and . . . [with] a 'full-scale' tunnel in which 

 complete aeroplanes up to 35-foot span can be tested. The present- 

 day American position in all branches of aeronautical knowledge can, 

 without doubt, be attributed mainly to this far-seeing policy and ex- 

 penditure on up-to-date laboratory equipment." 



Somewhat wryly, A. J. Sutton Pippard of the University of London 

 observed in 1935 "that many of our most capable design staffs prefer 

 to base their technical work upon the results of the American NACA." 



An important effort of the NACA was to make its research findings 

 fully available for use. First, there were Reports, comprehensive 

 presentations expected to have lasting value. Then there were Tech- 

 nical Notes, preliminary or narrower in scope. Technical Memoran- 

 dums were reprints, or translations, from the aeronautical literature 

 of other nations. Aircraft Circulars reported information about 

 foreign aircraft and engines. In later years Research Memorandums 



