210 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1954 



lage gave considerable directional fin area, and the very earliest 

 enclosed-fuselage types like the Nieuport had a very low, small, bal- 

 anced rudder at the end, so that they still required a great deal of 

 coordinating of the lateral and directional controls. But as our 60 

 years progress, we find the combined rudder and fin area becoming 

 larger and higher, until finally in the modern airplane of today it is 

 so high that much lateral balance is obtained from the rudder and fin 

 alone, and the necessity for coordination has more or less ceased to 

 exist. We have excellent planes that turn very nicely on ailerons and 

 equally good ones that are corrected laterally on fin and rudder alone. 

 Tail structure has also gone through an ever-lengthening develop- 

 ment. The "Kitty Hawk" was very short-tailed. Of course, it had 

 the front elevator, a questionably stable layout, which was in short 

 order replaced by a horizontal tail in the rear with a much greater 

 lever arm. But as we come down through the years we find tails of 

 good aircraft becoming longer and longer, and larger and higher, and 

 as we are about to wonder when this will stop, along comes the Delta 

 plane design and brings us abruptly to a halt. Of course modern 

 wing sections have been developed that have a very much smaller and 

 more stable center- of -pressure movement. And this makes the shorter 

 Delta wing configuration much more feasible. The Delta wing still 

 looks as if it will continue to have large fin and rudder areas with con- 

 siderable leverage around the center of gravity. 



There have been two body configuration developments through 

 these years slightly different from the natural growth of the covered 

 fuselage into the enclosed cabin, and into the large, roomy interior 

 bodies of the airliners of today. One, of course, is the Burnelli and 

 Northrup project of carrying the loads in a very thick wing. In the 

 case of the Northrup, this was carried even further into the "flying 

 wing" type where there was no tail at all. But as the "flying wing" 

 developed, what amounted to tails began to be added to the wing 

 tips, giving lateral and directional control leverage around the center 

 of gravity, introducing the complication of added surfaces and weight 

 of controls and their stresses. Whether for this or other reasons, the 

 tailless airplane has not survived, and not even in the case of the Delta 

 wing can we consider that it has survived because the successful Deltas 

 have such large fin and rudder tails. The other differing configura- 

 tion is the twin-boom holding tail structures such as in the Fairchild 

 Packet and the new Nord Atlas in France. There is a sound rea- 

 son for this twin-boom design that has nothing to do with either con- 

 trols or stability. It is the excellent way in which this configuration 

 allows for a cargo-carrying body with accessible doors very conven- 

 iently arranged for loading or parachute load dropping. The excel- 

 lence of this configuration is all the more accentuated when one 



