APRIL 25, 1907] 
INA Gs 
URE 
609 
AERODYNAMICAL EXPERIMENTS 
OBSERVATIONS IN RUSSIA. 
HE results of an extensive series of experiments 
upon the resistance of various forms of bodies 
in a current of air, as well as the particulars relating 
to various balloon ascents and observations upon the 
AND 
Fic. 1.—Yhe Aérodynamic Institute at Koutchino. 
height of clouds, are given in two publications | 
recently received from the Institut aérodynamique 
de Koutchino.! The institute (Fig. 1) was founded | 
for the purpose of studying air resistance and for | 
the scientific exploration of different layers of the | 
atmosphere. Besides the director and | 
members of the staff, there are 
in all twenty-one men employed, 
of whom six are labourers. 
The buildings and equipments 
cost 100,000 roubles. There is a 
dwelling house for the staff, a 
honorary 
hall, too fect by 43 feet by 
28 feet, for experimental work, 
and suitable workshops and 
tools. 
The experiments upon air re- 
sistance were made in a long 
cylindrical tube 48 feet long and 
4 feet diameter, shown in Fig. 2 
(a piece of the tube is temporarily 
removed to show the position of 
a small screw inside). The air 
current in this tube is produced 
by an electric fan, the power 
coming in the first place from a 
thirty horse-power steam engine. 
It was found at first that the air 
current in the tube was not 
uniform, and was not even sym- 
metrical about the axis of the 
tube, since greater proximity to 
the floor and one wall of the 
building produced a_ disturbing 
effect. This ditficulty was over- 
come by inserting the end of the 
tube into a large cylinder 7 feet diameter and 
12 feet long. The velocity of the air in the tube 
was carefully measured for various speeds of the fan, 
1 Institut aérodynan ijue de Koutchino. (St. Petersburg, 1905.) Bulletin | 
de l'Institut aérodynamique de Koutchino, Fascicule I (St. Petersburg: 
Golicke and Wiliborg, 1903.) 
NO. 1956, VOL. 75] 
and subsequently the velocity for each experiment 
was obtained from the number of revolutions of the 
fan. 
The weak point of this method is that the body 
which is being experimented upon in the tube pre- 
sents an obstacle to the free motion of the air, and 
therefore reduces the velocity, and furthermore, the 
walls of the tube exert an un- 
known influence upon the result 
excepting for quite small bodies 
placed near the centre. With a 
similar arrangement at the 
National Physical Laboratory, 
Mr. Stanton found that, work- 
ing with a tube of 2 feet 
diameter, he could not experi- 
ment upon a pressure plate of 
more than 2 inches diameter 
without finding that his results 
were vitiated by the influence of 
the walls of the tube. 
It is impossible in a_ brief 
notice to give an account of all 
the experiments; perhaps the 
most important are those show- 
ing the increased lifting power 
which a screw possesses when a 
current of air made to blow 
at right angles to its axis. 
Thus the lifting power with a 
horizontal current of 20 feet per 
second was found to be more 
than twice as great as with still air, although the 
driving power required was not increased. 
Details of the methods and results of four ascents 
of unmanned balloons are given, and it is noteworthy 
that in a country like Russia the instruments should 
be so often recovered. 
is 
Fic. 2.—Tube for Experiments on Air Resistance at the Aérodynamic Institute, K sutchino. 
The observations on clouds depend on the use of an 
electric search-light, and the observation, by a theo- 
dolite in the neighbourhood, of the position of the 
patch of lighted cloud. Unfortunately, the method 
can only be pursued at night, when the type of cloud 
is not very easy to determine. 
