INVENTION AND PRODUCTION OF NEW EXHAUST MUFFLER FOR AIRPLANES

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00810A006200420005-5
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 21, 2016
• Document Release Date: August 18, 2008
• Sequence Number: 5
• Publication Date: April 13, 1955
• Content Type: REPORT

Approved For Release 2008/08/18: CIA-RDP80-0081 OA006200420005-5
CENTRAL INTELLIGENCE AGENCY
INFORMATION REPORT
S-E-C-R-E-T
NOFORN
COUNTRY Czechoslovakia
DATE OF INFO.
PLACE ACQUIRED
This is UNEVALUATED
Information
NO. OF PAGES 3
REQUIREMENT NO. RD
REFERENCES
THE SOURCE EVALUATIONS IN THIS REPORT ARt DEFINITIVE
THE APPRAISAL OF CONTENT IS TENTATIVE.
(FOR KEY. SEE REVERSE)
1. The State Aeronautical Research Institue of Prague-
at the beginning of 1953 with the task of roducinga basis abnewstype as cexhaust
muffler for airplane engines that could be manufactured onamass-production
.
2. The task was summarized in the expression: "a good muffler of noises resulting
from exhaust gases in order to reduce to as little as possible the loss of
time for filling the cylinders of the engines with the mixture of fresh air
and vaporized gasoline." The muffling capacity of the new device must be
such that the noise generated by an engine in operation must not exceed 60
decibels at a distance of 150 meters. This means that at a height of about
500 meters an airplane should not be heard on the ground.
3. The problem was brilliantly resolved by means of a large column lined with
glass wool. In the cylinder of the column, the exhaust gases retain their
speed in accordance with Bernoullits equation: pressure and velocity remain
constant. The gases, when going through the column, lose their power to
develop noises without losing their velocity. In order to muffle any noises
that might be generated by the vibrations of the column itself, the column
is surrounded by a sheath, and the resulting space between this sheath and
the wall of the column is filled with compressed glass wool.
4. The first results of the experiment were satisfactory, of the new device was begun =`y, and as a result, mass
315 B (sic) of Radotin (N in January 1954. National Enterprise
was to complete by March 1954. allEt the preparation's formerly for the
5
mass produot~,' P. The
1954 plan called for the monthly production of 350 mufflers; this number
was to be stepped up to 500 in 1955. The glass wool, supplied in pre-cut
compressed sheets, is supplied by Podebrady Glass Works National Enterprise
S-XII-P-B.2
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NOFORN
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REPORT
Invention and Production of New Exhaust DATE DISTR.
Muffler for Airplanes 13 April 1955
Approved For Release 2008/08/18: CIA-RDP80-0081 OA006200420005-5
 Approved For Release 2008/08/18: CIA-RDP80-00810A006200420005-5
S-E-C-R E-T
NOFORN
2.1 Comment: The reference is presumably to the Podebrady Glass
Works (Podebradske sklarny) National Enterprise located at Jiraskova
trida 223 in Podebrady (N 50-09, E 15-08).
Legend to Annex
Noise Muffler for the Exhaust Gases of Airplane Engines
Scale: 1:15
A. Exhaust pipe from the engine
B. Exhaust pipe to the outside
C. Sheath with space filled with glass wool
D. Discs, disc-like screen
E. Rings, annular screen
F. Bell-shaped screen
G. Sheath (wall of column)
H. Outside sheath (of the outside container)
S-E-C-R-E-T
NOFORN
Approved For Release 2008/08/18: CIA-RDP80-00810A006200420005-5
 Approved For Release 2008/08/18: CIA-RDP80-0081 OA006200420005-5
S-E-C-R-E-T
NOFORN
-3-
Annex
Noise Muffler for the Exhaust Gases of Airplane Engines
Scale: 1:15
S-E-C-R_E-T
NOFORN
G
C
Approved For Release 2008/08/18: CIA-RDP80-0081 OA006200420005-5