Development and characteristics of translating horizontal tail assembly for supersonic aircraf

Spearman, M. L.

English

NASA Technical Reports Server

M. b. SPEARMAN 
TRANSLATING HORIZONTAL TAIJ, 
Filed March 5, 1968 
C 
c 
INVENTOR. 
MORRIS L. SPEARMAN 
BY q 4 L P  5 
d+* 
ATTORNEYS 
https://ntrs.nasa.gov/search.jsp?R=19710001568 2020-03-17T02:33:55+00:00Z
afente 
as contemplated by the p ent invention, involves me- 
chanical translation of the aft horizontal tail, in-flight, 
onis L. s ~ ~ ~ ~ ~ ~ ,  ~~.~~e N ~ ~ ,  vas, assigroor to the such that the tail is continuously used to provide lift, sta- 
kTnited States of America as represented by the Ad- bility, and control, but in varying amounts depending on 
ministrator of the National Aeronautics and Space 5 the tail longitudinal position. Thus, for low-speed flight, 
Administration and for takeo'ff and landing, the tail is translated rear- 
wardly to take maximum advantage of the tail moment 
arm in providing stabiiity and control. For transonic and US. C1.244-43 supersonic cruise flight, the tail i s  translated forward to a 
10 position directly behind the wing trailing edge. This tail 
ONTAL TAIL 
Filed Mar. , Ser. No. 710,533 
ht.  3/54,9/08 
translation brings the center of pressure forward in order 
to compensate for the increase in stability that occurs for 
An aircraft having both supersonic and subsonic flight fixed tail arrangements. 
capabilities which utilizes a translating horizontal tail to Accordingly, it is an object of the present invention to 
vary the aircraft geometry when changing from subsonic 15 provide a new and improved variable geometry c o d g -  
to supersonic speeds and vice versa. uration for supersonic aircraft. 
Another object of the present invention is the provision 
of a new and improved variable geometry aircraft with 
The invention described herein was made by an em- in-flight geometry Variation being accomplished without 
PloYee of the United States Government and may be 20 adversely affecting the control and stability character- 
manufactured and used by or for the Government of the istics of the aircraft. 
United States of America for governmental purposes with- Another object of the present invention is a variable 
out the payment of any royalties thereon or therefor, geometry aircraft of minimum mechanical complexity. 
This invention relates generally t o  aerial vehicles, and Another object of the present invention is a translating 
relates with particularity to supersonic aircraft having ex- 25 horizontal tail for supersonic aircraft. 
d e n t  subsonic flight capabilities and utilizing a translat- According to the present invention, the foregoing and 
ing horizontal tail to vary the aircraft geometry. One of other objects are attained by providing, in a powered air- 
the major problems associated with the design of super- craft having a conventional supersonic fuselage including 
sonic airplanes is the variation of longitudinal stability a swept fixed wing and fuselage carried propulsion engines, 
and control with Mach number. The purpose of the trans- 3o a translating horizontal tail movable from an aft to a 
lating horizontal tail of the present invention is to provide forward position. The translating horizontal tail of the 
a means of counteracting the variation of longitudinal present invention is designed to be located substantiaqy 
stability and control with Mach number that generally a t  the aft end of the aircraft fuselage during low-speed 
occurs with cruise or fighter-type aircraft and thereby tend flight and movable to a position just aft of the fixed 
to maximize the vehicle maneuver performance both at 35 swept wing trailing edge for high speed or supersonic 
subsonic and supersonic speeds. The variation generally flight. Suitable control mechanism is provided in the air- 
encountered consists of a substantial increase in longitu- craft fuselage for selectively translating the horizontal tail 
dinal stability in going from subsonic to supersonic speeds from its rearwardmost position to its forward position 
with an attendant loss in maneuvering capability. Factors 4o just aft of the aircraft wing. 
contfibuting to this increase in stability are (1) a rear- A more complete appreciation of the invention and 
ward shift of the wing center of pressure, ( 2 )  the carry- many of the attendant advantages thereof will be readily 
over lift from the wing to the afterbody, (3) the decrease apparent as the same becomes better understood by ref- 
in subsonic downwash induced at  the horizontal tail and erence to the following detailed description when consid- 
(4) the deployment of supersonic upwash. Possible a&- ered in connection with the accompanying drawings where- 
viation of the problem lies in minimization of the aero- 45 in: 
dynamic effects involved or in geometrically altering the FIG. 1 is a bottom plan view of the variable geometry 
aircraft as the Mach number is varied. Minimization of aircraft of the present invention with the horizontal tail 
the aerodynamic effects implies the use of low aspect ratio thereof disposed in an aft subsonic cruise attitude: 
lifting surfaces having inherently low values of lift curve 5o FIG. 2 is a bottom plan view of the aircraft of I?IG. 
slope and consequently little variation of lift with Mach 1 with the horizontal tail thereof disposed in a forward 
number. However, a reduction in Mach number effects supersonic cruise attitude; and 
by such means is obtained at the expense of desirable lift FIG. 3 is a-section taken along lines 3-3 of FIG. 2 
and drag characteristics. Various systems for alleviating illustrating the connection between the fixed wing and 
the Mach number effects by geometrically altering the air- 55 the translating horizontal tail. 
craft have been used previously and include (1) .folding Referring now more particularly to the . drawings 
wing tips of canard configuration, such as found in the wherein like reference numerals designate identical parts 
B-70, ( 2 )  folding or free-floating canard surfaces, and in each of the views, and more particularly in  PIG. 1, 
(3) variable wing sweep. there is shown a variable geometry planform aircraft gen- 
These prior art systems have been suitable for the pur- erally designated by the reference numeral 11. Aircraft 11 
poses intended but have generally resulted in a compro- is provided with a conventional fuselage 12 having a 
mise in a design whereby some components of the air- reaction propulsion motor system mounted therein, and 
craft are used efficiently only during a portion of the which is proportional to have a length to equivalent di- 
flight regime. A method of altering the aircraft geometry, ameter, or fineness ratio, suitable for supersonic flight. 
3,493,197 
3 
Aircraft 11 is provided with a fixed swept wing 13 pro- 
jecting outwardly from each side of fuselage 12. Each wing 
13 includes a straight leading edge 115 and a straight trail- 
7 which converge outwardly and rearwardly 
with respect to the adjacent side of the fuselage, toward 
a tip section 19 in a conventional manner. The empennage 
assembly of the present invention includes a horizontal 
tail 21 projecting from each side of fuselage 12. Hori- 
zontal tail 21 is provided with a straight leading edge 23 
and a straight trailing edge 25 which converge outwardIy 
and rearwardly, with respect to the adjacent side of the 
fuselage, toward a tip section 27. Suitable longitudinal 
control thps or elevators 29 are located along the trailing 
edge 2§ of tail 21. The tail leading edge 23 and the tail 
tip section 27 are constructed on the same angular arrange- 
ment as the wing trailing edge 17 and wing tip 19, re- 
spectively, so that when translating horizontal tail 21 
is moved to the forward high-speed position these edges 
will merge with each other to form a continuous straight 
surface for wing 13 and tail 21. Suitable lift and control 
flaps for wing 13 are also considered a necessary part of 
aircraft 111, but are not shown in the interest of clarity. 
Referring more particularly to FIG. 3, it is seen that 
tail 21 is adjacent to the blunt wing trailing edge 17 for 
supersonic flight and thus alleviates the wing base drag. 
The blunt trailing edge 17 provides sufficient strength 
and space for the installation of sophisticated high lift 
devices for low-speed flight. 
During takeoff and climb to  cruise altitude horizontal 
tail 21 would be in the aft position shown in FIG. 1. 
Upon the attainment of cruise altitude, tail 21 will be 
translated forwardly by suitable control mechanism, not 
shown, for acceleration of the aircraft through the tran- 
sonic speed range to the cruise Mach number and, upon 
attainment of the cruise Mach number, the tail 21 will 
have been moved to the position shown in FIG. 2 so that 
wing 13 and tail 21 constitute a substantially continuous 
lift surface The control mechanism for tail 21 may be 
either mechanical, electrical, hydraulic or any combina- 
tion of these as is conventional in movement of aero- 
dynamic controls for aircraft. The control mechanism 
effects selective translation of tail 21 along suitable slotted 
surfaces (not shown) provided in the side wall of fuse- 
lage 12. 
As mentioned hereinbefore, the primary purpose of the 
translating horizontal tail of the present invention is to  
counteract the variation of longitudinal stability and 
conrol with Mach number that generally occurs with 
cruise or fighter-type aircraft and thereby tend to maxi- 
mize the vehicle maneuver performance both a t  subsonic 
and supersonic speed. After the supersonic flight plan or 
portion of the flight is completed, and it is desired to land 
the aircraft, translating horizontal tail 21 will be moved 
to the aft position shown at FIG. 1 to provide a more 
stable aircraft suitable for subsonic cruise and landing 
capabilities. The position of the tail in the mid or aft 
positions results in an increase in minimum drag while 
the position of the tail in the forward position (FIG. 2) 
results in a reduction in minimum drag and provides the 
highest values of maximum lift-drag ratio at supersonic 
speeds. 
Obviously there are many modifications and variations 
of the present invention possible in the light of the above 
teachings. It is therefore to be understood that the inven- 
tion may be practiced otherwise than as specifically de- 
scribed. 
What is claimed as new and desired to be secured by 
Letters Patent of the United States is: 
I. An aircraft having both supersonic and subsonic 
flight capabilities comprising: 
a fuselage, 
propulsion means carried by said fuselage, 
a fixed wing connected to each side of said fuselage and 
projecting substantially horizontally and outwardly 
therefrom, 
4 
(a)  each said wing having a straight leading edge 
swept outwardly and reanvardly with respect to 
the adjacent side of said fuselage, 
(b) each said wing having a substantially straight 
tip section extending from the leading edge ex- 
tremity thereof inwardly and rearwardly with re- 
spect to the adjacent side of said fuselage, 
(c) each said wing having a substantially straight 
trailing edge swept outwardly and reanvardly 
with respect to the adjacent side of said fuselage 
and terminating at the rear extremity of said 
wing straight tip section, and 
a horizontal tail extending from each side of said 
(a)  each said horizontal tail having a straight lead- 
ing edge swept outwardly and rearwardly with 
respect to the adjacent side of said fuselage, 
(b) each said tail having a straight tip section ex- 
tending from the leading edge extremity thereof 
inwardly and reanvardly with respect to the ad- 
jacent side of said fuselage, 
(c) each said tail having a substantially straight 
trailing edge swept outwardly and rearwardly 
with respect to the adjacent side of said fuselage 
and terminating at the rear extremity of said tail 
tip section, 
each said tail being located in an aft position adjacent 
the aft end of said fuselage during aircraft takeoff 
and climb to cruise altitude, and 
means for translating each said tail forward as a unit 
for acceleration of the aircraft through the transonic 
speed range to the cruise Mach number so that upon 
attainment of the cruise Mach number said tail will 
have been moved forward to such position that the 
leading edge thereof is adjacent with said trailing 
edge of said wing to form a continuous lift surface. 
2. The aircraft of claim 1 wherein said wind straight 
trailing edge and said tail straight leading edge are swept 
outwardly and reanvardly, at the same angular relation- 
40 ship with respect to the adjacent side of said fuselage 
and the length of said wing straight trailing edge and said 
tail straight leading edge are substantially identical. 
3. The aircraft of claim 1 wherein when said tail is 
adjacent with said wing the straight tip sections of said 
45 tail and wing will also merge into a straight continuous 
tip section. 
4. The aircraft of claim 1 wherein said wing trailing 
edge is blunt to facilitate the installation of sophisticated 
high lift devices for low speed flight and said tail leading 
5o edge reduces the wing base drag when said tail is adjacent 
to said wing for flight of said aircraft a t  the design cruise 
Mach number. 
5. An aircraft having both supersonic and subsonic 
flight capabilities comprising: 
5 
10 
fuselage, 
15 
20 
25 
30 
35 
55 a fuselage, 
propulsion means carried by said fuselage, 
a fixed wing connected to each side of said fuselage 
and projecting substantially horizontally and out- 
wardly therefrom, 
a horizontal tail extending from each side of said fuse- 
lage, said horizontal tail being located in an aft posi- 
tion adjacent the aft end of said fuselage during air- 
craft takeoff and climb to cruise altitude, 
and means for translating said horizontal tail forward 
along said fuselage as a unit for acceleration of the 
aircraft through the transonic speed range to the 
cruise Mach number so that upon attainment of the 
cruise Mach number said tail will have been moved 
so that the leading edge of said tail contacts the trail- 
ing edge of said wing. 
4. The aircraft of claim 5 wherein said wing trailing 
edge is blunt along the length thereof and when said tail 
contacts said trailing edge a continuous lift surface is 
formed by said wing and said tail wherein the drag of the 
6o 
65 
70 
75 combination is reduced. 
3,493,197 
6 
FOREIGN PATENTS 
5 
7. The aircraft of claim 6 including lonigtudinal con- 
trol elevators positioned along the trailing edge of said 1,124,991 7/1956 France. 
tail. 
References Cited 
UNITED STATES PATENTS 
2,504,767 4/19501 Wallis _ _ _ _ _ _ _ _ _ _ _ _ _ _  244-46 
2,683,574 7/1954 Peterson _ _ _ _ _ _ _ _ _ _ _ _  244-46 
3,092,355 6/1963 Brown _ _ _ _ _ _ _ _ _ _ _ _ _ _  244-43 2 4 U 6 ,  87 
3,181,820 5/1965 Burnelli _ _ _ _ _ _ _ _ _ _ _ _ _  244-87 
MILTON BUCHLER, Primary Examiner 
J. L. FORMAN, Assistant Examiner 
U.S. C1. X.R. 


Translating horizontal tail Patent

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