NO. 3 EUROPEAN AERONAUTICAL LABORATORIES ZAIIM \J 



resistance of the driving and recording gear, the resistance to rolling of the 

 carriage and the air resistance of its elements, will all be determined once for 

 all, so that the power actually absorbed l)y tlie surfaces or screws under test 

 may be readily determinable. 



Full-scale iiicasurcDiciits. — We saw a full-scale Bleriot monoplane 

 mounted on one of the electric carrja^^es in such manner that its lift, 

 drift and moment, or center of pressure, could be determined at one 

 time, as it speeds across the tield. The speed through the air is 

 measured by means of a presstire-tube anemometer whose pressure 

 collector is a A enturi tube, and has to be calibrated, since its readings 

 are larger than those of a standard instrument such as used bv Eiffel, 

 Prandtl and others. The relative importance of such large scale 

 experiments as compared with model tests, or full scale flights with 

 instruments mounted on the aero])lane, has yet to be determined. If 

 of new type, the full-scale machine may be tested more safely on a 

 car. The measurements of lift here are said to be in error about 

 5 per cent : the drift measurements are much less accurate. 



A runndhoHse, which measures 120 feet in diameter, shelters a 

 whirling- table, the extremity of whose whirling arm descriijes a 

 circle 300 feet in circumference, and carries the models subject to 

 aerodynamic study. This can be used in any weather, while the 

 electric road can be used only at sj^ecial times, and most effectively 

 only during fair and calm weather. The whirling table, however, 

 does not seem to be so popular in the leading^ aerotechnical labora- 

 tories as the wind-tunnel and large field track. It is not an indis- 

 pensable part of an aeronautical laboratory, except where studies in 

 circular motion are to be made. 



Ancillary huildiiv^s have been erected on the grounds near the main 

 laboratory, one for the director immediately in charge, another for 

 the caretaker, who is also a workman assisting in the experiments. 



The reports of the investigations are published in the Bulletin 

 de rinstitut Acrotechnique de rUniversite de Paris. The annual 

 issues for 1912 and 1913 are in the Smithsonian library. 



Other French aeronautical laboratories, operating- on a smaller 

 scale, are worth mentioning, though unvisited Ijy me for want of time. 



The military establishment at Chalais-Meudon, in charge of the 

 Engineer Corps, and under direction of Commandant Dorand, 

 resembles the English Royal Air Craft Factory, in developing ex- 

 perimental air craft and making full scale tests ; but it does not 

 manufacture air craft on such a large scale', and does not compete 

 with commercial tirms in building for the government, but rather 

 stimulates and helps them to do their best work. 



