Vented vectoring-nozzle has superior thrust coefficient and is lighter in weight because it does not require completely enclosed elbow duct ordinarily used to deflect nozzle flow. Improved nozzle has primary nozzle and three-sided elbow deflector

Esker, D. W.

English

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Primary Nozzle 
Flhrw Sir 
Outer Wall 
Fan Hub 
Center - 
Body
Elbow 
1^1
May 1974	 B74-10058 
NASA TECH BRIEF 
Ames Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Vented Vectoring-Nozzle for STOL and V/STOL Aircraft 
Station 1	 Station 2
Thrust-vectoring nozzles are utilized on many 
STOL and V/STOL aircraft to provide powered lift 
for takeoff, landing, and transition to horizontal flight; 
they are also used to provide aircraft side-force con-
trol in the low-speed flight mode, in hovering, and 
whenever there is insufficient aerodynamic control. 
Inasmuch as aircraft payload capacity is sharply 
dependent on the efficiency of thrust-vectoring noz-
zles, it is necessary to utilize nozzles which provide 
a large thrust coefficient (i.e., ratio of the actual thrust 
to the thrust theoretically obtained from isentropic 
flow in the nozzle). In actual vectored nozzles, 
differences between theoretical thrusts and available 
thrusts are directly related to total internal pressure 
losses within the nozzles which, in turn, are primarily 
a function of nozzle internal geometries and total 
pressure levels of exhaust flows. The effect of total 
pressure losses on thrust performance becomes in-
creasingly important as the nozzle total pressure ratio 
(total pressure to ambient pressure) decreases below 
a level of 2.0; clearly, losses are particularly great in 
the nozzles used in fan-powered aircraft because ex-
haust total pressure ratios are about 1.3. The vec-
toring-nozzles of some V/STOL fighter aircrafts cur-
rently operate at pressure ratios of 2.2 with a thrust 
coefficient of 0.95; thrust coefficients of about 0.93 
have been reported for experimental nozzles at pres-
sure ratios in the vicinity of 1.3, but coefficients of 
the order of 0.98 must be available (at pressure 
ratios about 1.3) for aircraft of adequate payload 
and range. 
A vented vectoring-nozzle has been developed 
which, in experimental thrust performance tests at 
90° thrust deflection and nozzle pressure ratio of 1.3, 
has been found to have a thrust coefficient of 0.971 
(about 4% higher than presently known devices). In 
(continued overleaf) 
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addition to the demonstrated superior thrust coeffi-
cient at 90 0 -deflection at pressure ratio ranges of 1.1 
to 1.5, the new vectoring-nozzle is lighter in weight 
because it does not require the completely enclosed 
elbow duct ordinarily used to deflect nozzle flow. 
As illustrated in the diagram, the improved vented 
vectoring-nozzle consists of a primary nozzle and a 
three-sided elbow deflector. Airflow enters the de-
flector by way of a primary nozzle that is mated to 
the fan by an appropriate axial shroud which sur-
rounds the centerbody of the fan hub. The entry 
cross-section of height-to-width ratio 0.65; the cross-
section is reduced by 5 percent over the length (LP) 
of the primary nozzle. The nozzle has a length which 
is 0.381 times the diameter of the entry-cross section. 
The airflow ducted into the deflector from the 
primary nozzle is rotated 90° from the centerline of 
the primary nozzle by the three-sided elbow deflector, 
which has a rectangular, U-shaped cross-section of 
width equal to 1.07 times the width of the exit port 
of the primary nozzle; the side walls of the deflector 
are of a circular-sector shape. The deflector's outer 
walls have a radius of curvature (R) which is 1.25 
times the width of the section W. 
The high performance of the nozzle is attributed
to the absence of structure in the inner corner (region 
J) of the elbow deflector. It is anticipated that small 
variations of the nozzle geometry and dimensional 
ratios will not produce large changes in nozzle per-
performance as long as the entry port of the deflector 
is maintained free of structures which can interfere 
with fluid flows in the vicinity of the exit of the 
primary nozzle. 
Note: 
No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B74-10058 
Patent status: 
NASA has decided not to apply for a patent. 
Source: Donald W. Esker of 
McDonnel Douglas Corporation
under contract to

Ames Research Center 
(ARC-10839)
. 
Category 06 S


Vented vectoring-nozzle for STOL and V/STOL aircraft

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