Upper surface, external flow, jet-augmented flap configuration for high wing jet aircraft for noise reductio

Lowry, J. G.

Riebe, J. M.

Rogallo, F. M.

English

NASA Technical Reports Server

July 11, 1961 F. M. ROGALLQ =A1 
JET AIRCRAFT CONFIGURATION 
Filed May 6, 1959 
\ 
2,991,061 
2 Sheets-Sheet 1 
Fig. I 
Fig. 2 a  
Fig.  2 b  
'I 6 
W 
I NV ENTdRS 
FRANCIS M. ROGALLO 
JOHN M. RIEBE 
JOHN 0. LOWRY 
Y 
https://ntrs.nasa.gov/search.jsp?R=19700024021 2020-03-17T01:33:46+00:00Z
July 11, 1961 
Filed May 6, 1959 
F. M. ROGALLO E T A 1  2,991,961 
JET AIRCRAFT CONFIGURATION 
2 Sheets-Sheet 2 
Fig. 3 
19 
z 
Fib, 4 $=e DB. DB 
0" 30° 60" FLAP ANGLE 
Fig. 5 
INVENTORS 
FRANCIS M. ROGALLO 
JOHN M.RlEBE 
JOHN G,LOWRY 
BY 
2,991,961 
* Unired States Patent Q&CX patented July 11, 1961 
1 
2,991,961 
JET AIRCRAFT CONFIGURATION 
F’rnncle M. Rogallo and John M. Iuebe, Newport News, 
and John G. Lowry, HombyviUe, Va., assignors to the 
United States of America as represented by the Admin- 
istrator of the National Aeronautics and Space Ad- 
minishation 
Filed M a y  6, 1959, Ser. No. 811,509 
4 Claims. (CI. 244-12) 
(Granted under Title 35, U.S. Code (1952), sec. 266) 
The invention described herein may be manufactured 
and used by and for the Government of the United States 
for governmental purposes without the payment of any 
royalties thereon or therefor. 
This invention relates generally to a jet-augmented flap 
system for aircraft, and more particularly to an upper 
surface external flow jet-flap configuration for a high wing 
airplane having improved noise suppression character- 
istics. 
A jet-augmented flap may be defined in simple terms 
as an arrangement for simulating a flap by a jet sheet 
which augments the lift capabilities of an airfoil, or wing 
section, by inducing circulation of the stream around 
the wing. Although the advantage of these arrangements 
in providing higher lift and moment coefficients with the 
attendant reduction in the take-off and landing speed and 
distance of jet aircraft have been recognized by those 
skilled in the art, the arrangements heretofore proposed 
utilizing this principle have not been found to  be entirely 
satisfactory in all respects. In one presently used ex- 
ternal flow jet-flap arrangement, the engine nacelles are 
mounted on pods below the wing of the airplane and the 
jet exhaust thereof directed up through a slotted €lap and 
then down over the upper surface of the flap. Although 
an increase in lift is obtained from this prior art configura- 
tion, a considerable part of the lift is lost in wing inter- 
ference. This loss of lift has been determined to result 
from the forcing of the jet exhaust through the flap gap 
and the chordwise flow of the jet exhaust near the lower 
wing surface in a direction opposite to that necessary for 
circulation lift development. A further loss in lift is also 
experienced by this prior art low wing mounting position 
arrangement due to  the “ground effect” phenomenon, 
which occurs when a jet-flap is close to ground. More- 
over, this structural configuration lacks an inherent 
capability for effecting a reduction in the jet engine noise, 
and requires the utilization of separate jet noise supress- 
ing devices. An additional shortcoming in the low 
mounting position arrangement is its susceptilibity to 
operational malfunctioning or structural damage from 
“garbage inhalation.” 
Accordingly, it is a feature of this invention to provide 
a new and improved jet-augmented flap configuration for 
reducing the danger of “trash ingestion,“ diminishing the 
“ground effect” upon the lift, improve the slow-speed per- 
formance of jet aircraft, and effect substantial jet-noise 
suppression. 
It is an object of the present invention to provide a new 
and improved jet-flap aerodynamic configuration for 
blowing a jet stream over the trailihg edge flap of the 
wing section of a jet aircraft. 
Another object of the instant invention is the provision 
of a new and improved shielding flaptype jet engine 
noise suppressor. 
Still another object of this invention is to provide a 
high wing airplane having its engines externally mounted 
in a cluster in a forward location on the upper wing SUI- 
face and exhausting through a narrow rectangular slit 
along the surface of a flap. 
A further object of the present invention is to provide a 
new and improved jet-augmented shielding-flap arrange- 
ment for effecting a beneficial change in the noise radia- 
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tion pattern and spectrum, especially in the downward 
direction. 
Other objects and many of the attendant advantages of 
this invention will be readily appreciated as the same be- 
comes better understood by reference to the following de- 
tailed description when considered in connectbn with the 
accompanying drawings wherein: 
FIG. 1 is a fragmentary plan view of a jet-augmented 
flap configuration constructed according to  the instant in- 
vention; 
FIGS. 2A, 2B and 2C are cross-sectional side views 
of the jet-flap configuration of RG. 1 in different opera- 
tional positions; 
FIG. 3 is a graphical representation of the noise radia- 
tion patterns of divers exhaust nozzle configurations in 
the X Y  plane; 
FIG. 4 is a graphical representation of the noise radia- 
tion patterns of divers exhaust nozzle configurations in a 
plane parallel to the YZ plane, and, 
FIG. 5 is a graphical representation of the noise radia- 
tion pattern of the jet-flap configuration according t o  the 
present invention at  divers flap, angles. 
Referring now to the drawing wherein like reference 
characters designate the same or corresponding parts 
throughout the several views, and more particularly to 
FIG. 1 whereon a nacelle 11 enclosing a number of jet 
engines 12 in  a cluster is shown as being externally 
mounted at an inboard location upon a swept wing 13 of 
a high-wing aircraft having a fuselage 14. The inboard 
cluster arrangement of a number of jet engines in a single 
nacelle provides an advantage over an equal number of 
jet engines spatially positioned on a wing in that a con- 
siderable reduction in the diving moment is realized by 
this cluster arrangement, however it is to be understood 
that if additional thrust is required, it is within the scope 
of this invention to provide for additional clusters of en- 
gines on the wing. The jet engines 12 are preferably 
mounted in a forwardly position on the wing and exhaust 
through a narrow rectangular opening, or slit, 15 formed 
in the rear of the nacelle 11 onto the upper surface of an 
inboard trailing edge flap 16, when in an extended posi- 
tion. The exhaust sfit 15 is oriented on the wing in a 
manner to provide for the streamwise flow of the jet ex- 
haust thereby to increase the thrust during level flight of 
the aircraft. The nacelle 11 may be mounted entirely 
above the wing 13 or partially submerged in the upper 
surface thereof, as shown in the drawing. A trapdoor 
type of thrust reversal, or spoiler, vane 17 is provided in 
the nacelle 11 and normally forms a wall thereof, the 
operation of which will be more fully explained herein- 
after. 
It will be clear that without departing from the scope of 
the invention, the trailing edge flap 16 may either have a 
curved or plane configuration, and may either be of a 
partial or full span length. To provide the greatest lift 
during an allengines-out emergency condition, the flap 16 
is preferably of the slotted type. 
As shown in FIG. 2A of the drawing, during devel, or 
cruising, flight of the aircraft, the trapdoor vane 17 is in 
a retracted position and the trailing edge flap 16 in a 
flapzero $mise position thereby providing for the unde- 
flected rearward streamwise flow of the jet stream from 
the cluster of jet engines 12, as represented by the arrow- 
head 18. During slow flight of the aircraft, as in land- 
ing or takeaff, the lift capability of the wing 13 is in- 
creased by deflecting the flap 16 as shown in FIG. 2B, 
thereby deflecting the direction 18 of the jet stream down- 
wardly. For the $urpose of increasing the drag and re- 
ducing the lift, as on landing touchdown, the trapdoor 
vane 17 is moved into the path of travel of the jet stream 
thereby to deflect the jet stream upward and forward, as 
indicated by the arrowhead 18 in FIQ. 2C. 
a,eoi,eei 
3 4 
In addition to providing an increase in lift, the jet- causea the noise patterns to be rotated 811 approximately 
augmented flap configuration hereinbefore described also equal amount. Consequently, since the upper noise radi- 
has been found t o  provide a considerable suppression of ation lobe rotates downward the more the jet streamfs 
the jet engine noise during take-off and landing, par- deflected, care should be exercised in the use of large de- 
titularly in the downward direction. The nature of the ,j flection angles if the beneficial d u c t i o n s  in the down- 
noise suppression provided is of especial benefit to ground ward direction of the noise pattern are to be fully realized. 
observers as well as the occupants of the aircraft. Obviously many modifications and variations of the 
By way of comparison, FIG. 3 shows the overall noise present invention aye possible in the light of the above 
radiation patterns in the XY plane for a circular exhaust teachings. It is therefore to be understood that within. 
nozzle and a rectangular exhaust nozzle having a large 1 0  the scope of the appenddd claims the invention may be 
length to width ratio, both with and without a large flap. practiced otherwise than as spfifically described. 
Each of the nozzles is considered to have an equivalent What is claimed as new and desired to  be secured by 
exit area. The pattern for the circular jet 19 may be Letters Patent of the United States is: 
seen as being symmetrical about the exhaust axis and as 1. In an aircraft, a fuselage, a wing carried high by 
having its maximum radiation occurring about 40 de- 1; said fuselage, a plurality of jet engines arranged in a 
grees off the jet axis downstream of the nozzle. In the duster mounted on the upper surface of said wing, a 
case of the conventional rectangular slit exhaust nozzle nacelle enclosing said plurality of jet engines, a rectangu- 
21, a symmetrical noise pattern is also seen to occur, lar orifice formed in said nacelle for normally effecting 
but is somewhat diminished in the upstream direction. a rearward ejection of the jet exhaust developed by said 
When the jet exhaust from a rectangular nozzle attaches 20 plurality of jet engines, means adjacent said orifice for 
to and flows over a large flap, this configuration being selectively interrupting said rearward ejection and for de- 
represented by reference numeral 22, the noise pattern flecting the direction of flow of said jet exhaust, and a 
may be seen as being very unsymmetrical about the jet trailing edge flap over which said jet exhaust is directed 
exhaust axis. It therefore will be apparent that large to €low by said orifice when said flap is in an extended 
noise reductions result especially in the downward direc- 26 and deflected position. 
tion thereby benefitting both a ground observer as well 2. In an aircraft, a fuselage, a swept wing carried high 
as an occupant of the high-wing aircraft. Similar bene- by said fuselage, a preselected number of jet engines ar- 
ficial noise suppression occurs with the rectangular nozzle ranged in a cluster mounted inboard on the upper surface 
and attached flap configuration 22 in a plane parallel of said swept wing, a nacelle enclosing said jet engines, 
to the YZ plane, as shown in FIG. 4. 30 a slit having a narrow rectangular configuration formed 
In addition to the beneficial changes in the noise radi- in said nacelle for normally directing the jet exhaust de- 
ation pattern resulting from the rectangular nozzle-flap veloped by said jet engines in a rearward streamwise flow, 
configuration 22, equally beneficial changes in the noise a pivoted vane formed h the upper surface of said 
spectrum also result by reason of this configuration. Al- nacelle adjacent to said slit for selectively redirecting the 
though it has been heretofore recognized by those skilled 3,j normal rearward flow of said jet exhaust in an upward 
in the art that a change from a circular exhaust area to a and forwardly direction, and an inboard trailing edge flap 
rectangular slit exhaust area produces a shift in the acous- carried by said wing over which said jet exhaust is di- 
tic energy to the higher and less detectable frequencies, rected to flow by said slit when said flap is in an extended 
with sizable reductions in the low frequency end of the and defleoted poeition. 
spectrum, this shift was accompanied by an increase in 40 3. In an aircraft according to dah 2 wherein said 
the noise level at the higher frequencies. By the use of nacelle is mounted partially submerged in the upper 
the rectangular nozzle-flap configuration according to this surface of said swept wing. 
invention, large reductions at the high end of the acoustic 4. In an aircraft according to claim 3 wherein said 
spectrum also occur. This result is considered to result trailing edge flap is of a partial span in length. \ 
from the acoustic shielding effect provided by the upper 45 
surface of flap 16 and to the beneficial effects of flow 
attachment. 
FIG. 5 graphically illustrates the effect on the noise 
pattern resulting from the turning of the jet stream, as in 
FIG. 2B for lift augmentation. It will1 be noted from 60 
the noise patterns of FIG. 5 that turning the jet stream 
through the angles of 0 degree, 30 degrees, and 60 degrees 
References Cited in the Ale of this patent 
UNITED STATES PATENTS 
2,396,911 
1,178,843 
Anxionnaz et al. -_-_____ Mar. 19, 1946 
France ___-----------__ Dec. 15, 1958 
FOREIGN PATENTS 


Jet aircraft configuration Patent

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