DUSTING COTTON FROM AIEPLANES. 37 
SUGGESTIONS FOR FUTURE INVESTIGATIONS. 
Before any attempt at commercial airplane dusting can be made 
various other problems must be considered. For example, the de- 
sign of the plane should permit a hopper of the maximum carrying 
capacity. The most efficient dust delivery must be determined. Pos- 
sibly this will not be through the bottom of the fuselage. As the 
velocity of the slip stream varies widely at different points around 
the plane, the propeller effect should be thoroughly charted and the 
most efficient point of delivery of the dust located. At a point as 
far forward as the observer's cockpit, where the dust is being de- 
livered, the air stream from the propeller is a comparatively few 
feet in diameter, so that when the dust is dropped into it, this dust 
has only a short distance to fall before it reaches quiet air. If this 
distance could be increased, the effect of the air on the powder would 
be greater, and probably more of the pellets of material adhering 
together could be broken up into individual particles. It might be 
possible to accomplish this by the use of conduits which would de- 
liver the dust into the air at a point near the tail of the plane, 
where the diameter of the stream is greater. Such questions can be 
answered only by experiment. 
Possibly the exhaust from either one or both banks of cylinders 
could be piped through a conduit which would not give back pressure 
on the motor and which would still connect with the dust outlet to 
break up and dry out the dust. A more efficient spread might be 
secured by using a bifurcated device, delivering the dust on both sides 
of the fuselage ; or stream-line conduits might be arranged along the 
trailing edges of the wings to carry the dust for delivery either at the 
wing tips or at intervals on the wings. All such work would require 
careful designing and the cooperation of skilled airplane engineers 
who could appreciate and measure the hazards involved. 
The type of plane most desirable for dusting is still to be deter- 
mined. One important item will be to increase, just as much as is 
safe, the dust load which can be carried at any time by the plane, 
in order to increase flying time and decrease ground time and thus 
correspondingly increase the acreage allotment of a plane. In the 
experiments conducted the pilot was concerned only with flying the 
plane, and the dust was delivered entirely by the hopper operator, 
who rode in the observer's cockpit. Equipment could be arranged, 
however, so that it would not be nesessary to carry this hopper opera- 
tor, and poison could be substituted for his weight. Automatically 
operated hoppers can be easily developed with a very simple control 
beside the pilot, and he could start and stop the flow of poison 
whenever desired. The pilot is in a better position to do this than 
the observer, because he is better protected from the blast of the 
propeller, and as his view is not obstructed by the lower wings he 
has a better view of the fields. The development of special dusts 
for airplane work depends entirely on the perfecting of a regular 
delivery. If it were found possible to deliver dust uniformly and 
under thorough control with comparatively light doses, the ideal 
poison would be a highly concentrated form, which might be slightly 
more expensive per pound than any other, but would more than 
compensate for this by the greater acreage handled by a single 
charge and a single flight of the plane. On the other hand, if it 
does not prove possible to perfect dust delivery to this degree, and 
