182 SYMPOSIUM ON AERONAUTICS 



both in surface and in number, so that the shaft may be 

 shielded from alternating flexure, a condition certain to result 

 in early rupture. 



6. Simplicity and directness of operation the valve gear. 



7. Simplicity and directness of drive for all auxiliary machinery 



such as magneto, water and oil pumps. 



In connection with the general problem of lubrication, one of 

 the great problems, perhaps the one most important problem in 

 connection with the aeroplane prime mover, relates to the possibility 

 of developing metals of such physical properties or relations that 

 they will operate in sliding relation without serious abrasion and 

 without the need of constant lubrication, at least in terms of the 

 practice found necessary with the materials now employed. 

 Whether any such metals in pairs can be developed or whether the 

 surfaces of metals will admit of treatment in any way which will 

 reduce in marked degree the amount of lubrication required, is of 

 course an open question ; but the march of scientific and engineering 

 progress is marked with many discoveries and developments seem- 

 ingly far more remote from possibility than is this. In any event 

 it is a field well worthy the most careful investigation, not alone for 

 its importance in connection with aeronautic prime movers but also 

 for the far-reaching influence which it would have throughout the 

 whole field of engineering design. It represents moreover a serious 

 need in the case of the aeronautic prime mover with reference to in- 

 creased safety, simplicity and decreased cost of operation. 



These problems, and others allied, all ofifer inviting fields for the 

 research engineer, the designer and the inventor. It is, further- 

 more, difificult to overestimate their importance. Thus the rupture 

 of a small oil pipe, perhaps Ys inch diameter, due to vibration result- 

 ing in a crystallization of the metal at a point of attachment, might 

 result in the failure of lubricant to reach some important element 

 of the engine, as a consequence of which the bearing heats, abrades, 

 perhaps seizes, the engine stops and possibly disaster comes swiftly 

 as a consequence. When safety of life may depend on continuous 

 operation of the engine, no item or element bearing on reliability is 

 too small to receive the most serious and earnest efforts on the part 



