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EP-4377208-B1 - SYSTEM AND METHOD FOR IMPROVED AIR-LAUNCH OF A LAUNCH VEHICLE FROM A TOWED AIRCRAFT

EP4377208B1EP 4377208 B1EP4377208 B1EP 4377208B1EP-4377208-B1

Inventors

  • COLE, GREGORY, M.
  • GALLO, MICHAEL, J.

Dates

Publication Date
20260506
Application Date
20220725

Claims (15)

  1. A launch system (20) for orbital or suborbital air-launch of a payload, the system comprising: a tow aircraft (30); a towed aircraft (50) selectively in tow behind the tow aircraft (30) at take-off and in flight via an interconnected tow cable (40), the towed aircraft (50) having a towed aircraft body (54) defining a towed aircraft central axis (68) and being selectively powered as by having a throttleable and restartable towed aircraft propulsion system (52) installed on or within the towed aircraft (50) for pull-up and climb upon release of the towed aircraft (50) from tow at a desired first altitude; a launch vehicle (70) releasably carried on the towed aircraft (50), the launch vehicle (70) having a launch vehicle body (74) defining a launch vehicle diameter (D) and a launch vehicle central axis (88) and being selectively powered as by having a launch vehicle propulsion system (72) installed on or within the launch vehicle (70) for propulsion upon release of the launch vehicle (70) from the towed aircraft (50) at a desired second altitude; and an articulatable carriage (90) releasably coupling the launch vehicle (70) with the towed aircraft (50), the towed aircraft (50), launch vehicle (70), and articulatable carriage (90) together defining an air-launch assembly (100), the articulatable carriage (90) configured for selectively shifting the launch vehicle (70) between a stowed position adjacent to the towed aircraft (50) and a deployed position spaced from the towed aircraft (50), thereby allowing for reduced drag with the launch vehicle (70) in the stowed position during tow and during pull-up and climb after release from tow and further allowing for reduced adverse aerodynamic effects between the towed aircraft (50) and the launch vehicle (70) with the launch vehicle (70) in the deployed position at release of the launch vehicle (70) from the towed aircraft (50), whereby upon release of the launch vehicle (70) from the towed aircraft (50) the towed aircraft flight path diverges from the launch vehicle flight path and the launch vehicle propulsion system (72) is activated to air-launch the launch vehicle (70) and deliver the payload (P) to higher altitude; wherein the articulatable carriage (90) comprises a rigid support (92) pivotally mounted between a rigid at least one forward arm (94) and a rigid at least one rearward arm (96), the support (92) providing axial, lateral, and rotational stability to the launch vehicle (70), and the arms (94, 96) pivotally engaged with the support (92) are configured for selective kinematic movement of the support (92) and thus of the launch vehicle (70) relative to the towed aircraft (50).
  2. The system (20) of claim 1 wherein in the deployed position of the air-launch assembly (100) the spacing of the launch vehicle body (74) from the towed aircraft (50) is a distance of approximately one-quarter the launch vehicle diameter (D) or more.
  3. The system (20) of claim 1 wherein in the deployed position of the air-launch assembly (100) the launch vehicle central axis (88) is at an inclined angle relative to the towed aircraft central axis (68), whereby in the deployed position the towed aircraft (50) has a negative angle of attack relative to the launch vehicle (70); and wherein optionally the negative angle of attack is in the range of one to ten degrees (1-10°), or wherein optionally the launch vehicle (70) in the deployed position of the air-launch assembly (100) is forward relative to the launch vehicle (70) in the stowed position of the air-launch assembly (100).
  4. The system (20) of claim 1 wherein a lengthwise trough (56) is formed on the towed aircraft body (54), and wherein optionally the articulatable carriage (90) is installed in the trough (56) such that in the stowed position of the air-launch assembly (100) the launch vehicle (70) is at least partially positioned within the trough (56).
  5. The system (20) of claim 1 wherein the articulatable carriage (90) is configured to be selectively free-standing to facilitate assembly of the launch vehicle (70) thereon prior to installation within the towed aircraft (50).
  6. The system (20) of claim 1 wherein the articulatable carriage (90) is installed on an upper side of the towed aircraft body (54) such that the air-launch assembly (100) involves a top-carry arrangement of the launch vehicle (70) on the towed aircraft (50).
  7. The system (20) of claim 1 wherein the launch vehicle (70) is selected from the group consisting of a propulsion system, an ordinance, an aero vehicle, a fairing, a projectile, a container, a carrier, and a cannister.
  8. The system (20) of claim 1 wherein the second altitude is more than 3048 m (10000 feet) greater than the first altitude.
  9. A method of employing a launch system (20) as defined in claim 1 for orbital or suborbital air-launch of a payload (P), the method comprising the steps of: releasably coupling the launch vehicle (70) with the towed aircraft (50) via the articulatable carriage (90) to form the air-launch assembly (100); configuring the air-launch assembly (100) in the stowed position with the launch vehicle (70) adjacent to the towed aircraft (50); towing the air-launch assembly (100) via the tow aircraft (30) and interconnected tow cable (40) to the first altitude; releasing the air-launch assembly (100) from tow at or above the first altitude; activating the towed aircraft propulsion system (52) and initiating a pull-up and climb maneuver of the towed aircraft (50) to the second altitude, the second altitude being more than 3048 m (10000 feet) greater than the first altitude; articulating the articulatable carriage (90) to shift the air-launch assembly (100) to the deployed position with the launch vehicle (70) spaced from the towed aircraft (50); releasing the launch vehicle (70) from the articulatable carriage (90) and thus from the towed aircraft (50); and powering the launch vehicle propulsion system (72) for further altitude gain or to meet specific mission requirements.
  10. The method of claim 9, prior to the step of towing the air-launch assembly (100), comprising the further step of activating the towed aircraft propulsion system (52) to provide take-off assist to the tow aircraft (30).
  11. The method of claim 9, prior to the step of releasing the air-launch assembly (100) from tow at or above the first altitude, comprising the further step of activating the towed aircraft propulsion system (52) to allow for recovery of the air-launch assembly (100) in the event of air-launch abortment.
  12. The method of claim 9 wherein the steps of articulating the articulatable carriage (90) and releasing the launch vehicle (70) from the articulatable carriage (90) occur substantially simultaneously; or wherein the step of articulating the articulatable carriage (90) comprises orienting the towed aircraft (50) at a negative angle of attack relative to the launch vehicle (70).
  13. The method of claim 9, after the step of releasing the launch vehicle (70) from the towed aircraft (50), comprising the further step of executing an aerodynamic maneuver, such as a bunt-over maneuver, of the towed aircraft (50) to further diverge the flight path of the towed aircraft (50) from the flight path of the launch vehicle (70).
  14. The method of claim 9 wherein one or more of the steps are achieved via control system automation.
  15. The method of claim 9, prior to the step of releasably coupling the launch vehicle (70) with the towed aircraft (50), further comprising the step of assembling the launch vehicle (70) on the articulatable carriage (90).

Description

RELATED APPLICATIONS This international patent application filed under the Patent Cooperation Treaty claims priority pursuant to PCT Article 8 to and is entitled to the filing date of U.S. Non-provisional Patent Application Ser. No. 17/386,189 filed July 27, 2021, and entitled "System and Method for Improved Air-Launch of a Launch Vehicle from a Towed Aircraft." BACKGROUND The subject of this patent application relates generally to launch vehicle air-launch employing a towed aircraft, and more particularly to launch systems and methods for selectively powering and operating the towed aircraft and selectively shifting the launch vehicle from a stowed position to a deployed position relative to the towed aircraft at or prior to launch vehicle release and launch. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. Despite early successes of tow-launch and some studies indicating that such may be a preferred alternative to ground-launch and conventional air-launch, and thus a preferred space launch approach generally, for satellite and other orbital deployment as well as suborbital applications, challenges have remained, including around the objective of optimizing such a modified air-launch approach wherein the launch vehicle is air-launched from a towed aircraft rather than a conventional aircraft. Key design, construction, assembly, and integration considerations for the safe, sound, and effective use of such tow-launch techniques involve, and in many respects hinge on, the means or methods of taking off with, carrying, deploying, and releasing or launching the launch vehicle and its payload relative to the towed aircraft. Numerous variables relate to weight and lift, energy requirements, altitude, airspeed, airflow and other aerodynamic influences, release angle, and other launch requirements and flight profile and/or launch sequence characteristics. A related and specific challenge is safely and effectively separating the launch vehicle from the towed aircraft at the desired altitude and orientation while avoiding any impact or recontact of the launch vehicle and towed aircraft, which could be catastrophic, as the two bodies are decoupled and move independently in relation to each other. Document US8727264B1 discloses, according to its abstract, an orbital launch system and its method of operation which use a maneuver to improve the launch condition of a booster rocket and payload. A towed launch aircraft, to which the booster rocket is mounted, is towed to a predetermined elevation and airspeed. The towed launch aircraft begins the maneuver by increasing its lift, thereby increasing the flight path angle, which increases the tension on the towline connecting the towed launch aircraft to a towing aircraft. The increased tension accelerates the towed launch aircraft and booster rocket, while decreasing the speed (and thus the kinetic energy) of the towing aircraft, while increasing kinetic energy of the towed launch aircraft and booster rocket by transferring energy from the towing aircraft. The potential energy of the towed launch aircraft and booster rocket is also increased, due to the increased lift. The booster rocket is released and ignited, completing the launch. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary. In the following description the following conversion is to be applied: 1 foot (ft) equals 0.3048 m. SUMMARY Aspects of the present invention teach certain benefits in construction and use which give rise to the exemplary advantages described below. The present invention solves the problems described above by providing a new and improved launch system and method for orbital or suborbital air-launch of a payload. In at least one embodiment, a launch system according to claim 1 is disclosed. In at least another embodiment, a method according to claim 9 is disclosed. Other objects, features, and advantages of aspects of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate the invention. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate aspects of the present invention. In such drawings: Figure 1 is a schematic view of an exemplary flight profile of a launch system, in accordance with at least one embodiment;Figure 2 is an enlarged schematic side view depicting an exemplary towed aircraft and launch vehicle as in Fig. 1 in tow behind a tow aircraft, in accordance with at least one embodiment;Figure 3 is a further schematic side view depicting the exemplary towed aircraft and launch vehicle as in Fig. 2 now released from tow behind the tow