Patent Application
20220119134
This disclosure relates generally to a novel Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) port small payload mounting system that permits maximum mass utilization of each ESPA port without regard to center of gravity constraints. In one or more embodiments, the apparatus and method include connecting, in the unused central volume of an ESPA ring, the adjacent faces of at least two payloads on opposing sides of an ESPA ring with a cross-reaching moment transmitting structure that reduces moments transmitted to the ESPA ring.
For the purposes of interpreting the disclosure made herein the terms “payload” and “satellite”, or derivations thereof, are used interchangeably and should be considered synonymous. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
An ESPA ring can be generally defined as a device that permits a single launch vehicle to carry a multiple number of individual payloads by mounting one or more cylindrical shaped ESPA rings on the top of the last stage of a launch vehicle and then attaching one or more payloads radially on each ESPA port. Many ESPA ports reside on the outside diameter of each the ESPA ring cylindrical structure and may contain multiple payloads that fit between the outer diameter of the ESPA ring and the inside diameter of the fairing of a launch vehicle. In some cases, one or more ESPA rings are located under a primary payload, where the primary payload is mounted on a traditional axial mounting structure on the top of the uppermost ESPA ring. In some cases, one or more ESPA rings are utilized to carry multiple satellites on a single launch vehicle without carrying a traditional axial mounted payload on the top of the uppermost ESPA ring. An example of such a compliment is used on SpaceX Rideshare missions.
The ESPA ring has provided many more launch opportunities for smaller payloads since its introduction but it has a serious flaw. The radial cantilevered mounting of the payloads on the ESPA mounting ports generates a tremendous moment on the ESPA ring when the launch vehicle is experiencing the largest acceleration load along the axial direction of the launch vehicle. The maximum moment imposed on the ESPA port is the product of the axial acceleration of the launch vehicle multiplied by the mass of the payload further multiplied by the distance of the center of gravity from the plane of the ESPA port. The maximum mass that can be tolerated by each ESPA port is reduced as the center of gravity distance of the payload is increased from the plane of the ESPA port.
In most cases, the available volume of a payload between the outer diameter of the ESPA ring and the inner diameter of the launch vehicle fairing determines a standard size of payload, generally this payload volume is called an “ESPA class” payload. In most cases, designing a payload with an offset center of gravity is not practical and as such, the center of gravity is generally located at approximately 50% of the radial length of the payload from the ESPA port plane. For example, in the case of a 24 inch diameter ESPA port on a SpaceX Rideshare mission this has the effect of reducing the maximum mass carrying capacity of an ESPA ring for the maximum CG distance (102 cm) from the ESPA port plane by a factor of (840 kg/250 kg) 3.36×. In fact, the maximum mass (800 kg) can only be accommodated with a center of gravity at 26 cm. This would generally limit the height of a maximum mass payload to only 52 cm. This is generally not practical.
To elaborate further on this problem, the volume available for payloads on an ESPA ring between the outer diameter of the ESPA ring and the inner diameter of the launch vehicle fairing increases in the radial direction as the ESPA payload volumes are generally “pie” shaped. Thus, there is more available volume for satellites at a distance farther away from the ESPA port plane which, as stated earlier, tends to reduce the available launch mass capability due to the large moment arm imposed on the ESPA port by the payload.
Additionally, the volume on the inside diameter of an ESPA ring is generally unused since the payloads are mounted on the outer diameter faces of the ESPA ring.
The disclosed subject matter helps to avoid these and other problems in a new and novel way.
This disclosure relates generally to a novel Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) port small payload mounting system that permits maximum mass utilization of each ESPA port without regard to center of gravity constraints. In one or more embodiments, the apparatus and method include connecting, in the unused central volume of an ESPA ring, the adjacent faces of at least two payloads on opposing sides of an ESPA ring with a cross-reaching moment transmitting structure that reduces moments transmitted to the ESPA ring.
A second disclosure relates to an alternate method of transmitting moments to a larger diameter cylindrical structure with its long axis oriented parallel and concentric with the launch vehicle and ESPA ring which lies between the ESPA ring and the fairing of the launch vehicle and is attached to the payloads surrounding the ESPA ring which distributes moments transmitted to the ESPA ring.
A third disclosure combines the two previous disclosures to ensure efficient load transfer to the ESPA ring.
According to the teachings of the present disclosures, there is here provided an ESPA payload mounting system that utilizes 1. a cross-reaching moment transmitting structure that connects adjacent faces of ESPA payloads on opposing sides of an ESPA ring or, 2. a larger diameter cylindrical structure with its long axis oriented parallel and concentric with the launch vehicle and ESPA ring which lies between the ESPA ring and the fairing of the launch vehicle and is attached to the payloads or, 3. A combination of the previous two methods.
In all the embodiments, for the payloads to separate and deploy from the ESPA ring after arrival of the launch vehicle to the deployment destination, the payloads are attached to their respective ESPA ports by well-known separation systems. This is easily accomplished by utilizing any well-known separation system known in the prior art (e.g. a separation nut, pyrotechnic nut, Marmon clamp, etc.) that fastens the payload to the ESPA port.
The moment transmitting structure must also permit the payloads to separate from the ESPA ring and from each other while still transmitting moments between the payloads while the moment transmitting structure is still connected (in the case of the cross-reaching moment transmitting structure) to the opposing located or (in the case of the outer cylindrical moment transmitting structure) to the adjacent payloads. This is also accomplished by utilizing any well-known separation system known in the prior art (e.g. a separation nut, pyrotechnic nut, Marmon clamp, etc.) that fastens the moment transmitting structure to the payload(s).
In the first and third embodiments the cross-reaching moment transmitting structure should be sized such that the outer diameter of the cross-reaching moment transmitting structure readily fits through the inner diameter of the ESPA port hole that pierces the ESPA ring. This permits the moment transmitting structure (if desired) to be ejected with the payload. As such, this normally unused volume in an ESPA ring can be utilized for additional extremely valuable payload volume. It should be noted that the moment transmitting structure could remain behind with the ESPA ring after the payload deployment event if desired.
In the second and third embodiments the larger diameter moment transmitting cylindrical structure generally should be sized such that the outer diameter of the moment transmitting cylindrical structure forms the base mounting diameter of the payloads. This provides the maximum bracing advantage to the payloads and contributes to efficient distribution of moments throughout the structure.
The main advantages of using the inventive mounting system is that it maximizes the mass utilization of each ESPA port without imposing the previously stated onerous center of gravity location constraints on the payloads.
Descriptions of certain illustrative aspects are described herein in connection with the figures. These aspects are indicative of various non-limiting ways in which the disclosed subject matter may be utilized, all of which are intended to be within the scope of the disclosed subject matter.
Other advantages, emerging properties, and features will become apparent from the following detailed disclosure when considered in conjunction with the associated figures that are also within the scope of the disclosure.
The present subject matter will now be described in detail with reference to the drawings, which are provided as illustrative examples of the subject matter to enable those skilled in the art to practice the subject matter. Notably, the figures and examples are not meant to limit the scope of the present subject matter to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements and, further, wherein:
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments in which the presently disclosed process can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for providing a thorough understanding of the presently disclosed method and system. However, it will be apparent to those skilled in the art that the presently disclosed process may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the presently disclosed method and system.
In the present specification, an embodiment showing a singular component should not be considered limiting. Rather, the subject matter preferably encompasses other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present subject matter encompasses present and future known equivalents to the known components referred to herein by way of illustration.
The figures herein provided, in conjunction with the written description here, clearly provide enablement of all claimed aspects of the disclosed subject matter. Accordingly, in
Deployment of the payload assemblies 300 occurs when separation systems 302 and 304 release the payload assemblies 300 and they may be radially ejected from ESPA ring 100 using well known means (e.g. separation springs). Note that central coupling device 305 remains attached to one of the payload assemblies 300 to prevent generation of additional space debris. It is also important that the diameters of moment transmitting structures 303 and central coupling device 305 are less than the diameter of ESPA port aperture 104 to permit ejection of the payload assemblies 100. It is also evident that moment transmitting structures 303 can be used for additional payload assembly 300 volume utilization.
Deployment of the payload assemblies 300 occurs when separation systems 302 and 501 release the payload assemblies 300 and they may be radially ejected from ESPA ring 100 using well known means (e.g. separation springs). It is also evident that moment transmitting structures 500 can be used for additional payload assembly 300 volume utilization.
Deployment of the payload assemblies 300 occurs when separation systems 302, 304 and 501 release the payload assemblies 300 and they may be radially ejected from ESPA ring 100 using well known means (e.g. separation springs). It is also evident that moment transmitting structures 303 and 500 can be used for additional payload assembly 300 volume utilization.
In summary, here has been shown an ESPA payload mounting system that utilizes 1. a cross-reaching moment transmitting structure 303 that connects adjacent faces of ESPA payloads 300 on opposing sides of ESPA ring 100 or, 2. a larger diameter cylindrical structure 500 with its long axis oriented parallel and concentric with the launch vehicle and ESPA ring 100 which lies between ESPA ring 100 and the fairing of the launch vehicle and is attached to the payloads 300 or, 3. A combination of the previous two methods that accomplishes the goal of maximum mass utilization of each ESPA port without regard to center of gravity constraints.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
The detailed description set forth here, in connection with the appended drawings, is intended as a description of exemplary embodiments in which the presently disclosed subject matter may be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments.
This detailed description of illustrative embodiments includes specific details for providing a thorough understanding of the presently disclosed subject matter. However, it will be apparent to those skilled in the art that the presently disclosed subject matter may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the presently disclosed method and system.
The foregoing description of embodiments is provided to enable any person skilled in the art to make and use the subject matter. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the novel principles and subject matter disclosed herein may be applied to other embodiments without the use of the innovative faculty. The claimed subject matter set forth in the claims is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. It is contemplated that additional embodiments are within the spirit and true scope of the disclosed subject matter.
The present application claims priority from U.S. Provisional Patent Application Ser. No. 63/094,702, filed on Oct. 21, 2020, which is incorporated herein by its entirety and referenced thereto.
| Number | Date | Country | |
|---|---|---|---|
| 63094702 | Oct 2020 | US |
