A Decexxiai. Record 4.0 



and lightened as much as possible through the use of hghtening holes. 

 The proper selection of species and thicknesses of piles resulted in an 

 appreciable increase of strength without increase in weight. Similar 

 parts were designed for several Xavy planes. 



3Iuch attention was devoted to the use of thin plywood as a wing 

 co^'ering and a number of tests were made in the hope of developing a 

 satisfactory linen substitute. Several types of construction were tried 

 out, and interesting preliminary results secured. Xo covering or type 

 of construction was perfected, however, which was superior to the 

 standard wood and linen type. 



BcveJopmcnt of Waicr-rcHlstant Glues 



Closely associated with most of the aircraft problems upon which 

 the laboratory worked was the all-important one of glues and gluing. 

 A great deal of reliance is placed upon glue in tlie construction of the 

 ordinary plane, since many of tlie structural parts are glued together, 

 and it is essential that only the best glues and l)est gluing technique 

 be employed. The first request for help came from the Signal Corps 

 in the spring of 1917, asking for assistance in hide glue inspection. 

 Xo standard, usable system of grading and inspection was available, 

 but one Mas quickly developed at the laboratory by an inspector as- 

 signed to the work, and all hide glue used by tJie Army Air Service 

 as well as much of that used by the X^avy Air Service was inspected 

 and certified by liim and his assistants. 



Attention was then directed to the great desirability of using 

 Avater-resistant glue in aircraft construction, not alone on account of 

 exposure to the weather wlien in service, but also ])ecause of tlie severe 

 conditions during shipment and storage. It had been known for many 

 years that so-called "'water-proof" glues could be made from blood 

 albumin and from casein, and various secret formulas had been devel- 

 oped and were in use to a certain extent. In fact, it is well established 

 that the enemy was using casein glue in his aircraft ])efore our entrance 

 into the war. In tliis country there were se^'eral small manufacturers 

 of "waterproof" plywood glued with blood albumin. However, there 

 Avas not available for general use an appreciable amount of a suitable 

 water-resistant glue, for either plywood or joint work. Therefore, 

 the perfection of several types of Avater-resistant glues was immedi- 



