SCIENTIFIC - AIRCRAFT INSTRUMENTS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600230409-3
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: July 18, 2011
• Sequence Number: 409
• Publication Date: June 10, 1949
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3
CEN i RAL Ii`fVTEL IGENCE ` 't' REPORT
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS CD NO.
COUNTRY Poland
SUBJECT' Scientific - Aircraft instruments
HOW
PUBLISHED Monthly periodical
WHERE
PUBLISHED Poland
DATE
PUBLISHED Nov 1947
LANGUAGE. Polish.
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SOURCE
DATE OF 1947
INFORMATION
DATE GIST. /0 Jun 19119
NO. OF PAGES 3.
SUPPLEM'NT TO
REPORT NO.
THIS IS UNEVALUATED INFORMATION
Skieg d1et= Po sue, Vol nT, No 11. (30), 1947
19~ Per Abe 72T96 -- Trans3dtian requested.)
EuO.olph Urich, Halt!' I&ento mart
Aerial Observer
The altitude of an aircraft is still being determined by the traditional
barometric method.; howeTar, this met;iod has many faults. On the iaesmtive side
are errors resul'isg from the eetimatbd calculation of temperature and atmos-
pheric pressure on the earth's surface at the spot where the measunremsats are
taken, the Inability to determine precisely the altitude of topographic features
below the aircraft at various altitudes, etc.
In this connection, altimeters have been constructed to measure directly
the rblative altitude of the aircraft in flight, independently of pressure
mad other alaospheric conditions. In this class belong aoorstioal, opoical,
and ratio altimeters.
Tice most darycrtaat of these, from a flight standpoint, is the radio
altimeter for law a1litudes ranginC from sere to 1,200 asters (see appended
figure).
Principle of Oration of Radio Altisstier for *a , A.1titus
The basic slesents of the altii,ter arm the transmitter and the re-
eel'sar. The transmitter constantly snits eleotromagpetia .',`Iclees.at
trequeaeies varying continuously from 1s0O to 440 mesLoyoles.
Throughout the whole period of operation, the transmitter, by z. a
of the transmitting antenna, sirs to the ground signals of a definite
frequency. These signals are reflected from the gra and aM reach the
receiver via the receiving antesaa.
tt'ATS NAM
AM11f N[
CLASSIFICATION
INSas I
Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3
 Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3
Simultaneously, in addition to the signals reflected: by the eart1' the
tuned circuit of the receiver receives signals directly from the transmitter.
Because of the fact that the distance trateled by the reflected signal is
longer than that covered by the direct signal, the reflected signal reaches
the receiving antenna with a certain time lag, which causes a difference between
the frequencies of the two signals. When the 3irect signal and the reflected
signal are'conbined, beats result and a corresponding voltage is set up in the
antenna bf.the receiver.
The current corresponding to the beat frequency is then eapliled in
the saplifier of the receiver and conducted to tha`irequency aster, where it
is converted into direct currant having ? voltage directly proportional to the
beat frequency. The direct current is tranaitted to the indicator of the
altimeter and causes a displacea?nt of the indicator hand.
Inasaach as both the beat frequency and the voltage are directly propor-
tionsl to the altitude, the altimeter can be calibrated in asters.
The altimm"r consists of the trasmaitters, the transmitting antenna,
cockpit; the receiving and transaittin6 antennas are placed under the wings
of under the fuselage,-, 3isytn :ppatrt. The indicator is built into the
instrument panel.
To Increase the Wp?'eoision of altitude readings, two scales are used
on the indicator: frok 0 to 120 asters andifroa 0 to 1,200 asters. Co ..ta-
tibn frost am scale to the other is by asene of the commutator placed on the
indicator.
The altimeter takes its power fro>t the plane's 26-volt circuit. `1'he
weight of the ec.aipsosnt (without cables) is 12 kilogreas.
R i S of H& Altimeter AMWO
So radio altimeter alusys asavares the shortest distance between the
surfi.oe of the earth and the aircraft. When the airoraff I. of abing, the
indicator Land anves in the direction of the higher readl%s It conformity
with the increasing altitude. At en altitude of over 120 raters; it cease
to a stop at the right eat of the scale.
Men the aircraft continues to climb to an altitude exceeding 250 to
30r' Inters, the indicator hand starts to fall and any reach zero as a re-
sult of the feting of the reflected signal.
Although the equipment does not give faulty results at altitudes ex-
sedi g the Baits of the first scale, nevertheless, when the altitude
sm"Aw 120 asters, it ie necessary to pass over to the seoond,?scale.
When the aircraft is flying at an altitude exceeding the range of the sazond
scale,, at first the IMiuator hand st:~ps at the right end of th4o scale, cad
upon continued asosntddriUS a a result of the fading of the reflected signals.
Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3
 Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3
During long flights at alti lee ezeeeding the range of the second
scale, the altimeter should V disoemsedted. During flight over uneven
terrain, the indicator of-the altiseeter nay be observed to oscillate,
conforming to the altitude of.obaeotd on the terrain (elevations, ravines,
Mountains, buildings, etc.). During flight over, a forest,the instrument
indicated the Distance between the ground` nd the aircraft, If the forest
is very dense and leafy, the Instrwdnt.in..icaten the altitude not f'rcm,-the
ground. but from the lea`7,boughs.of the trees,
The instrument does not react to elevation ahead of the aircraft. In
fli ,ght over, esep;aountains with sharp peaks, the instrti at indicates the
altitude:'of the aircraft meaem?ed not frog the, euommit of the mountain, .
but from the el.ipe The readings of the inetruaont beccae faulty and cannot
be need.
In steep turns, the readings of the altimeter are unsteady and inaccurate.
Use of the radio altimeter at low altitudes in airforce Its of the
Soviet Arm had proved that, in conaunotion with other navigation and radio-
navigation instruments, 'it a= be applied successfully for instrument flying,
for penetrating a low ceiling and.for instrument landings.
ranea.tter reseiyor Og sgnbetor
9 sadniator Y I aatplifie
. I I
IEreaaaitt_ ode eotor frequen indicator
transaitting
autesaa
. '~ resolving
J antenna
sot signals
Sanitized Copy Approved for Release 2011/07/18: CIA-RDP80-00809A000600230409-3