DUSTING COTTON FROM AIRPLANES. 39 
type, with the speed of the propellor ordinarily ranging from 1,480 
to 1,550 E. P. M. The main gasoline tank holds 78 gallons and the 
emergency tank holds 9. The gasoline consumed is from about 
20 to 25 gallons an hour, so that such a plane would have a dusting 
time of about 3-| hours on a single filling. The motor holds about 8 
gallons of oil and consumes practically 2 gallons per hour, and it 
also should be drained after every 5 hours of flying time and new 
oil added. The minimum safe ground speed of the D. H. plane 
is about 65 miles, and the maximum speed is about 120 miles per 
hour. The greater power and lift of this plane makes it possible 
to climb much more rapidly, and thus it could more easily avoid ob- 
structions than the Curtis. On the other hand in some flying its 
much larger size might prove a handicap. One decided advantage 
it would possess is the fact that it has a carrying capacity of be- 
tween 500 and 700 pounds, which would permit a much longer time 
in the air for dusting from each filling of the hopper. 
These two types of planes are the only ones studied. Other models 
should by all means be considered, since both of these were developed 
several years ago and the more recent models probably have more 
desirable characteristics for this type of flying. 
COST OF OPERATION. 
A few calculations relating to costs of operation are presented 
for what they are worth. 
Each plane should have one or more pilots and two mechanics. In 
fact, since a plane would find favorable flying conditions about 7 or 8 
hours a day, and it would be difficult for a pilot to stand more than 4 
hours of such flying each day, the most economical arrangement 
might be to provide two pilots for each plane. These pilots would 
cost at least $300 a month each, and the mechanics would cost $150 a 
month each. 
In the following computations a day's work of one pilot and a 
plane has been figured at 4 hours. The pilot would probably fly 
about 5 days a week, and in cotton dusting would have about 6 weeks 
to fly, or a total of 120 flying hours yearly on this particular assign- 
ment. It would of course be necessary to pay his salary for the 
entire } T ear. At $3,600 a year, this would make a charge of $30 per 
flying hour for the pilot. One mechanic would be charged to each 
pilot, and a three months' flying period only charged, because this 
mechanic could always be used on other duties the remainder of the 
year. Consequently, the charge is $450 for each season, or $3.75 per 
hour for each plane. 
Summarizing these figures, we have the following costs for a 
4-hour day operation of a Curtis plane : 
Pilot $120 
Mechanic 15 
40 gallons of gasoline at 25 cents 10 
8 gallons of oil at $1 8 
Total 153 
These figures would probably be reduced considerably if the opera- 
tion were placed on a commercial basis, but they compare very favor- 
ably with ordinary dusting machine figures. The figures available 
indicate that one plane operating 4 hours a day would take care of 
