A design method of moving the center of pressure backward for a reusable aerospace vehicle
By installing a rotatable pitch stabilizing plate at the tail section of the aerospace vehicle, the problem of insufficient pitch static stability margin caused by changes in the pressure center position is solved, and pitch stability adjustment and aerodynamic performance improvement are achieved under different flight conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CALCULATION AERODYNAMICS INST CHINA AERODYNAMICS RES & DEV CENT
- Filing Date
- 2019-11-12
- Publication Date
- 2026-07-21
Smart Images
Figure CN110775296B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a design method for shifting the center of gravity of a reusable aerospace vehicle, and more particularly to a design method for enhancing the pitch stability margin of a reusable aerospace vehicle based on a pitch stabilizing plate, belonging to the field of aircraft technology. Background Technology
[0002] Reusable spacecraft are a new type of aircraft that combines aviation and aerospace capabilities. They can maneuver flexibly in the atmosphere and low Earth orbit according to different mission requirements. Reusable spacecraft fly higher and faster than traditional aircraft, and are more flexible and reusable than conventional spacecraft. They not only meet the fundamental need for rapid and inexpensive access to space, but also enable instantaneous arrival on a global scale. Therefore, reusable spacecraft have become a strategic high ground for major spacefaring nations to compete for space dominance and space advantage.
[0003] Aside from the retired reusable space shuttles, the development of spaceplanes in various countries around the world is still in the research and verification stage. Currently, projects under development mainly include the US X-37B space orbital maneuvering vehicle and the XS-1 experimental spaceplane; the UK's Skylon; India's Reusable Vehicle Technology Demonstrator (RLV-TD); and China's Tengyun project. Among these, the X-37B experimental vehicle, as the US Air Force's newest and most advanced reentry vehicle, primarily serves to provide low-risk technologies for reusable spacecraft and to develop new experimental methods and unconventional operational concepts. It is considered a key component of maintaining the US's future space dominance. Since 2011, the X-37B has conducted five orbital flight missions (all completed, the most recent returning on October 27, 2019, after 780 days in orbit), and a sixth orbital flight mission is planned for November 2019.
[0004] For reusable spaceplanes, the unique requirements for lift-drag matching and handling-stability matching across a wide airspace and speed range pose significant challenges to their aerodynamic layout design. Spaceplanes like the US X-37B, during atmospheric reentry flights, operate at Mach numbers ranging from 0.2 to 25 and angles of attack from 5 to 40 degrees. This wide range of speeds and attitude adjustments leads to significant changes in the center of pressure position, making it difficult to simultaneously ensure longitudinal stability for both hypersonic and subsonic / transonic speeds when designing their aerodynamic layout. To guarantee aerodynamic performance and heat protection requirements at high Mach numbers, spaceplanes typically employ a wing-body configuration with a low-aspect-ratio swept wing and a V-tail. The wing is located in the mid-fuselage section, and body flaps, borrowed from the Space Shuttle design, are used for pitch trim control. Studies have shown that under low to medium Mach numbers and medium-angle flight conditions, the pressure center of this type of aerospace vehicle is relatively forward, and even with full optimization of the original aerodynamic layout, there may still be insufficient static stability margin. Summary of the Invention
[0005] The purpose of this invention is to address the aforementioned problems by providing a design method for reversing the center of gravity of a reusable aerospace vehicle. This invention can shift the center of gravity of the aerospace vehicle backward and adjust the pitch stability of the aerospace vehicle under different flight conditions.
[0006] The technical solution adopted in this invention is as follows:
[0007] A design method for a reusable aerospace vehicle with a rearward shifted pressure center involves symmetrically installing a pair of pitch stabilizing plates on both sides of the tail section of the aerospace vehicle fuselage. The pitch stabilizing plates are connected to the fuselage via rudder shafts, and the pitch stabilizing plates can rotate around the rudder shafts to switch between the open and retracted modes of the pitch stabilizing plates.
[0008] In the above scheme, the pitch stabilizing plate rotates around the rudder axis. When the pitch stabilizing plate is close to the side of the fuselage, it is in the retracted mode, which can maintain the basic aerodynamic layout of the spacecraft. When the pitch stabilizing plate rotates outward by 90° around the rudder axis and unfolds into a movable component similar to a stabilizing wing, it is in the open mode. Since the pitch stabilizing plate is perpendicular to the incoming flow, the drag generated can be used entirely to form a nose-down moment, so as to maximize the rearward displacement of the pressure center position, thereby improving the pitch static stability margin of the spacecraft.
[0009] Preferably, the mounting azimuth angle of the rudder shaft is selected based on the angle of attack during flight in the pitch stabilizer activation mode.
[0010] Preferably, the mounting azimuth angle of the rudder shaft is 20°-30°.
[0011] Preferably, during the reentry flight of the aerospace vehicle, when the flight Mach number is 3-5 and the flight angle of attack is 20±5°, the pitch stabilizer is in the open mode; in other flight states, the pitch stabilizer is in the retracted mode.
[0012] The pitch stabilizer is raised by a servo motor installed inside the fuselage, putting it in the open mode. In other flight conditions, the pitch stabilizer is in the retracted mode.
[0013] Preferably, the pitch stabilizing plate is aligned with the tail end of the aerospace vehicle in the retracted mode.
[0014] Preferably, the pitch stabilizing plate is trapezoidal.
[0015] Preferably, the pitch stabilizing plate is a right-angled pentagon.
[0016] Preferably, the basic aerodynamic layout of the spacecraft is generated parametrically using a type function and shape function-based (CST) method.
[0017] Preferably, the aerospace vehicle includes a head, fuselage, wings, flaps and ailerons, speed brakes, tail and body flaps; the wings are located on both sides of the fuselage, the flaps and ailerons are located at the trailing edge of the wings, the tail is located at the rear of the fuselage, the speed brakes are located between a pair of tails, and the body flaps are located at the rear of the aerospace vehicle.
[0018] Preferably, the head adopts a blunt spherical design, the fuselage adopts a semi-circular plus rounded square cross-section design, the wing is a double delta wing composed of a slender leading edge wing and a short delta wing, and the flaps and ailerons are full wingspan designs.
[0019] This invention discloses a reusable aerospace vehicle with a rearward-shifted pressure center design. To address the severe aerodynamic heating problem during high-speed reentry, the nose adopts a blunt spherical design, and the fuselage uses a semi-circular plus rounded square cross section, ensuring full volume utilization. The wings on both sides are double delta wings composed of slender leading-edge extensions and short delta wings, exhibiting good hypersonic lift-drag characteristics. Full-span flaps and ailerons are designed on the trailing edge of the wings for roll control. The speed brakes for terminal energy management and drag control during approach and landing are located between a pair of V-tails, which function as both rudders and elevators. Additionally, the vehicle has body flaps at the rear, primarily for pitch trim during high angle-of-attack flight.
[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0021] 1. In the pitch stabilizer activation mode, since the pitch stabilizer is perpendicular to the incoming flow when in use, the resulting drag can be used entirely to generate a nose-down moment, thereby maximizing the rearward shift of the pressure center position and improving the pitch static stability margin of the aerospace vehicle.
[0022] 2. Compared with conventional pitch stability enhancement schemes such as increasing body flaps, widening body flaps, and adding horizontal stabilizers, the pitch stabilizer can be retracted when not in use. At this time, it will not generate any additional aerodynamic forces, nor will it affect the aerodynamic characteristics and aerodynamic data of the original scheme. It is especially suitable for improving the aerodynamic performance of aircraft in specific flight phases. While achieving the same pitch stability enhancement effect, the design scale of the present invention is relatively small. Attached Figure Description
[0023] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:
[0024] Figure 1 This is a schematic diagram of the mechanism for aerospace vehicles based on the rearward movement of the pitch stabilizing plate's pressure center;
[0025] Figure 2 This is a schematic diagram of the pitch stabilizer's activation mode;
[0026] Figure 3 This is a schematic diagram of the pitch stabilizer plate in retracted mode;
[0027] Figure 4 This is a schematic diagram of the pitch stabilizing plate structure;
[0028] Figure 5 This is a schematic diagram of another structure of the pitch stabilizing plate;
[0029] Figure 6 This is a three-view drawing of an aerospace vehicle with a pitch stabilization plate.
[0030] The markings in the diagram are: 1-Head, 2-Fuse, 3-Wing, 4-Flap and aileron, 5-Speed brake, 6-Tail, 7-Body flap, 8-Pitch stabilizer, 9-Connection edge between the pitch stabilizer and the rudder shaft. Detailed Implementation
[0031] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.
[0032] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.
[0033] Example 1
[0034] The basic aerodynamic layout of the spacecraft in this embodiment is generated parametrically using a type function and shape function-based method (CST), with more than 50 design parameters. The basic parameters are as follows: overall fuselage length 8.9 meters, overall fuselage width 4.3 meters, overall fuselage height 2.9 meters, nose radius 0.3 meters; wing root length 3.5 meters, width 1.5 meters; V-tail overall length 1.6 meters, width 0.8 meters; body flaps length 0.8 meters, width 1.3 meters, thickness 0.2 meters.
[0035] A pair of trapezoidal pitch stabilizing plates are symmetrically installed on both sides of the tail section of the aerospace vehicle. The pitch stabilizing plates are connected to the fuselage via rudder shafts, with the connecting side of the pitch stabilizing plate and the rudder shaft forming the waist of the trapezoid. In the retracted mode, the pitch stabilizing plates are aligned with the tail end of the aerospace vehicle. The basic parameters of the trapezoidal pitch stabilizing plates are as follows: lower base L0 is 1.5 meters, upper base L1 is 0.3 meters, height H is 1.0 meter, rudder shaft installation azimuth angle θ is 30°, and effective wetted area is 1.8 square meters.
[0036] The reusable aerospace vehicle pressure center shifting design method of this embodiment allows the aerospace vehicle pressure center to be shifted back by 1% of the total fuselage length when the side pitch stabilizer changes from the retracted mode to the open mode under the conditions of a flight Mach number of 4 and a flight angle of attack of 25 degrees.
[0037] Example 2
[0038] The basic aerodynamic layout of the spacecraft in this embodiment is generated parametrically using a type function and shape function-based method (CST), with more than 50 design parameters. The basic parameters are as follows: overall fuselage length 8.9 meters, overall fuselage width 4.3 meters, overall fuselage height 2.9 meters, nose radius 0.3 meters; wing root length 3.5 meters, width 1.5 meters; V-tail overall length 1.6 meters, width 0.8 meters; body flaps length 0.8 meters, width 1.3 meters, thickness 0.2 meters.
[0039] A pair of right-angled pentagonal pitch stabilization plates are symmetrically installed on both sides of the tail section of the aerospace vehicle. The pitch stabilization plates are connected to the fuselage via rudder shafts, with the connecting side of the pitch stabilization plate and the rudder shaft being the hypotenuse of the right-angled pentagon. In the retracted mode, the pitch stabilization plates are aligned with the tail end of the aerospace vehicle. The basic parameters of the right-angled pentagonal pitch stabilization plates are as follows: the bottom edge L0 is 1.5 meters, the height H1 of the rudder shaft from the bottom edge is 0.5 meters, the total height H is 1.3 meters, the installation azimuth angle θ of the rudder shaft is 30°, and the effective wetted area is 3.0 square meters.
[0040] The reusable aerospace vehicle pressure center shifting design method of this embodiment allows the aerospace vehicle pressure center to shift back by about 2% of the total fuselage length when the side pitch stabilizer changes from the retracted mode to the open mode under the conditions of a flight Mach number of 4 and a flight angle of attack of 25 degrees.
[0041] In summary, by adopting the reusable aerospace vehicle center-shifting design method of the present invention, the center-shifting of the aerospace vehicle can be shifted backward, and the pitch stability of the aerospace vehicle under different flight conditions can be adjusted.
[0042] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.
Claims
1. A design method for shifting the pressure center of a reusable aerospace vehicle, characterized in that: A pair of pitch stabilizing plates are symmetrically arranged on both sides of the tail section of the aerospace vehicle. The pitch stabilizing plates are connected to the fuselage through a rudder shaft. The pitch stabilizing plates can rotate around the rudder shaft to realize the switching between the pitch stabilizing plate open mode and the retracted mode. When the pitch stabilizing plates are in the open mode, the center of gravity of the aerospace vehicle can be moved backward. When the pitch stabilizing plates are in the retracted mode, they are aligned with the tail end of the aerospace vehicle.
2. The design method for repositioning the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: The mounting azimuth angle of the rudder shaft is selected based on the angle of attack during flight in the pitch stabilizer activation mode.
3. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: The mounting azimuth angle of the rudder shaft is 20°-30°.
4. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: During the reentry flight of the aerospace vehicle, when the flight Mach number is 3-5 and the flight angle of attack is 20±5°, the pitch stabilization plate is in the open mode.
5. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: The pitch stabilizing plate is trapezoidal.
6. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: The pitch stabilizing plate is a right-angled pentagon.
7. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 1, characterized in that: The basic aerodynamic layout of the spacecraft is generated parametrically using a type function and shape function-based (CST) method.
8. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 7, characterized in that: The aerospace vehicle includes a nose, fuselage, wings, flaps and ailerons, speed brakes, tail and body flaps; the wings are located on both sides of the fuselage, the flaps and ailerons are located at the trailing edge of the wings, the tail is located at the rear of the fuselage, the speed brakes are located between a pair of tails, and the body flaps are located at the rear of the aerospace vehicle.
9. The design method for shifting the pressure center of a reusable aerospace vehicle as described in claim 8, characterized in that: The nose adopts a blunt spherical design, the fuselage adopts a semi-circular plus rounded square cross section design, the wing is a double delta wing composed of a slender leading edge wing and a short delta wing, and the flaps and ailerons are full wingspan designs.