Evening star., 1928-03-18

tered. well, I guess we'll CO. Ex-
perts convinced him that a thin-bladed
metal propeller was the most efficient.
| So the Spirit OF st. Louis was equipped
| with propeller built according to sug-
| gestions made by the bureau. Lind
bergh had in his plane numerous other
! devices that the bureau helped to per-
| feet
| Aeronautical research Is concerned
with the testing Of engines under high
altitude conditions and the testing Of
model airplanes In wind tunnels where
gentle" breeZes blow 20 miles an hour.
These breezes are not blown" through
tunnels: their force Is suction. A four
biaded propeller at one end exhausts
the air at such rapid pace that new
air gushes In at rate OF about 10
miles an hour How an airplane wing
reacts under stress can here be meas
ured accurately. Recently the wind
tunnel has been used to test the
stanchness OF roof ventilators and
auto accessories exposed TO the wind.
The objection 10 airplane toy-riding
that Is voiced by many Is problem
In the hands OF the bureau The muf-
fling OF motor noises Is possible, but
not without sacrifice of some OF the
pay load. That Is the most recent
dictum. 1t was found that by piping
noises over the engine and TO the rear
OF the passengers a good part Of the
noise can be eliminated. Another way
Is 10 pad the cabins with insulating
material.
The solution that presents itself
now" said Hugh Dryden, In charge OF
the work, rs TO throw out one pas
senger for the benefit OF the three
others~that is. the weight Of the
fourth must be converted into piping
and insulating material"
In another laboratory high powered
airplane motors are being tested for
fuel consumption and fabrication. A
l0-gallon can Of gasoline on an accu-
rate scale and stop watch serve 10
tel the rate at which motor burns
'uel at certain speed. Then there
are endurance tests: In fact. any prob
iem That concerns the aviator Is faced
ana eventually solved at the bureau,
me navy has sponsored a good deal
oi work IN connection with instrtl-
niehts used In aeronautics
The viii Of the late Prof. II. M. Per-
Eins OF Ohio Wesleyan Uniyersity pro.
Vlded Tor an astronomical observatory
whose equipment was 10 be American
exclusively Came the problem of OBJ
tanning 70~inch optical disc for the
nbSfFvabory's rejecting telescope No
american hrm would undertake It's
manufacture. Before giving up, an APP
peal was made 10 the Bureau Of Stand |
ARDS, and A. ~ Finn. In charge OF the !
HlasS section. Immediately started his |
pots boiling
Up 10 that time. all the large teia- !
scope mirrors came from Europe. The !
largest In the world, the i00-inch re- |
hector In the Mount Wilson 0baeFva. !
tofy. wha made In France.
After four unsuccessful attempts, |
Fltln fused 900 pounds 6f high~grade !
optical glass With 1900 pounds of sand |
ana Chemicals, The melt was stirred |
Ior Alx hours, then tapped. The glass |
Io"ed INTO mold where IL c0ngealed !
slowly, for the mold itself was care
iuliy constructed c0ngeaiing furnace, In |
Whicn temperature could be controlled |
within degree. While the tampera- |
lure at The time OF pouring was 2.400 |
degrees r., one week later 1t had |
reached only Liza degrees r,
IN al, The cooling Of that disc re- |
aiiired nine solid months. When the |
glass was fnaiIy unveiled" II was |
found 10 be practically ftawlegs. IL |
such sihH had been made IN America,
The bureaus clear understanding Of
The method will soon be- transmitted |
10 American manufacturers, who will |
DE able tO compete with foreign prod |
ucfs.
The large Tefiectars produced abroad
are cast from ihe combined meIis nf |
several pots, The disc for the Ohla
school WsE made from the contents Of |
single pot, probably the largest auany
NY ssst Houted from one eontalnas.