Exclusion of Tethered Launches From Licensing Requirements
Federal Register, Volume 77 Issue 164 (Thursday, August 23, 2012)
Federal Register Volume 77, Number 164 (Thursday, August 23, 2012)
Proposed Rules
Pages 50956-50963
From the Federal Register Online via the Government Printing Office www.gpo.gov
FR Doc No: 2012-20686
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 400 and 401
Docket No.: FAA-2012-0045; Notice No. 12-05
RIN 2120-AJ90
Exclusion of Tethered Launches From Licensing Requirements
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to exclude tethered launches as defined in this proposal from the existing licensing requirements. This proposed rule would maintain public safety for these launches by providing launch vehicle operators with clear and simple criteria for a safe tethered launch. The FAA would not require a license, permit or waiver for tethered launches that satisfy the design and operational criteria proposed here.
DATES: Send comments on or before October 22, 2012.
ADDRESSES: Send comments identified by docket number FAA-2012-0045, using any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your comments electronically.
Mail: Send comments to Docket Operations, M-30; U.S. Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at (202) 493-2251.
Privacy: The FAA will post all comments it receives, without change, to http://www.regulations.gov, including any personal information the commenter provides. Using the search function of the docket Web site, anyone can find and read the electronic form of all comments received into any FAA dockets, including the name of the individual sending the comment (or signing the comment for an association, business, labor union, etc.). DOT's complete Privacy Act Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
Docket: Background documents or comments received may be read at http://www.regulations.gov at any time. Follow the online instructions for accessing the docket or Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: For technical questions concerning this proposed rule, contact Shirley McBride, Commercial Space Transportation, Federal Aviation Administration, 800 Independence Avenue SW., Washington, DC 20591; telephone (202) 267-7470; email Shirley.McBride@faa.gov.
For legal questions concerning this proposed rule, contact Sabrina Jawed, AGC-240, Office of the Chief Counsel, Federal Aviation Administration, 800 Independence Avenue SW., Washington, DC 20591; telephone (202) 267-8839; email Sabrina.Jawed@faa.gov.
SUPPLEMENTARY INFORMATION: See the ``Additional Information'' section for information on how to comment on this proposal and how the FAA will handle comments received. The ``Additional Information'' section also contains related information about the docket, privacy, and the handling of proprietary or confidential business information. In addition, there is information on obtaining copies of related rulemaking documents.
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Authority for This Rulemaking
The Commercial Space Launch Act of 1984, as amended and re-codified at 51 U.S.C. 50901-50923 (the Act), authorizes the Department of Transportation and thus the FAA, through delegations, to oversee, license, and regulate commercial launch and reentry activities, and the operation of launch and reentry sites as carried out by U.S. citizens or within the United States. 51 U.S.C. 50904, 50905. The Act directs the FAA to exercise this responsibility consistent with public health and safety, safety of property, and the national security and foreign policy interests of the United States. 51 U.S.C. 50905. Title 51 U.S.C. 50901(a)(7) directs the FAA to regulate only to the extent necessary, in relevant part, to protect the public health and safety and safety of property. The FAA is also responsible for encouraging, facilitating, and promoting commercial space launches by the private sector. 51 U.S.C. 50903.
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Background
The FAA's licensing and permitting requirements for commercial space launches are contained in 14 CFR chapter III. Section 400.2 specifies the requirements in chapter III apply to commercial space transportation activities conducted in the United States or by a U.S. citizen, but do not apply to amateur rocket activities or to space activities carried out by the United States Government on behalf of the United States Government.
The FAA began hearing of tethered launches around 2002, when launch operators tested relatively small vehicles tethered to the ground with engines that burned for short periods of time. Operators later tested larger, more developed and costly vehicles by attaching them to a tether and attaching the tether to a crane or forklift to prevent the vehicle from hitting the ground. Some of these tethered launches met the FAA's amateur rocket activity criteria,\1\ and thus were excluded from chapter III requirements. Those that did not meet the amateur rocket criteria should have been required to comply with chapter III. However, because these launches had a tether system that restrained the vehicle within a certain range, the FAA initially deemed them low risk and did not require operators to conduct tethered launches under chapter III. In 2008, the FAA reassessed this determination and found that launches that meet the applicability criteria of Sec. 400.2, regardless of whether the launch vehicle is restrained by a tether, must be conducted under chapter III. That is, operators must apply for a license, permit or waiver. That year, the FAA reviewed and granted five chapter III waiver requests to conduct tethered launches. The agency now seeks an approach to tethered launches that would maintain public safety and be less burdensome on launch operators and the FAA. That approach is the subject of this proposed rule.
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\1\ Prior to 2008, ``amateur rocket activities'' was defined in 14 CFR Sec. 401.5 as ``launch activities conducted at private sites involving rockets powered by a motor or motors having a total impulse of 200,000 pound-seconds or less and a total burning or operating time of less than 15 seconds, and a rocket having a ballistic coefficient--i.e., gross weight in pounds divided by frontal area of rocket vehicle--less than 12 pounds per square inch.'' In 2008, the FAA moved the definition to 14 CFR part 1, chapter I and revised it as follows: ``Amateur Rocket means an unmanned rocket that is propelled by a motor or motors having a combined total impulse of 889,600 Newton-seconds (200,000 pound-
seconds) or less; and cannot reach an altitude greater than 150 kilometers (93.2 statute miles) above the earth's surface.'' 14 CFR 1.1; Requirements for Amateur Rocket Activities, Final Rule, 73 FR 73781 (Dec. 4, 2008).
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Overview of Proposed Rule
Title 51 U.S.C. 50901(a)(7) directs the FAA to regulate only to the extent necessary, in relevant part, to protect the public health and safety and safety of property. Therefore, the FAA proposes to reduce the scope of chapter III by excluding tethered launches that meet the requirements of this proposed rule. This proposal would maintain public safety by creating threshold criteria to determine whether chapter III needs to apply. FAA oversight would no longer be required for these launches because of the comprehensive protection the proposed launch vehicle, tether system, and operational criteria would provide.
This rulemaking would not affect amateur rocket activities, regardless of whether they include a tether system, because chapter III regulations do not apply to the launch of amateur rockets. Those operators that conduct launches covered under chapter III and are not eligible for the exclusion proposed here, must continue to follow current requirements by applying for a license, permit or waiver.
The FAA is proposing a number of changes consistent with the goals of Executive Order 13610, Identifying and Reducing Regulatory Burdens, 77 FR 28469 (May 14, 2012). This proposal, if adopted, would require that the launch vehicle be unmanned, be powered by a liquid or hybrid engine, and carry no more than 5,000 pounds of propellant. It would also require that the tether system, including the points of attachment within the tether system, meet specified structural criteria, and that the tethered operations be carried out within specified separation distances from the public. The structural criteria would mitigate the hazards that can compromise the structural integrity of the tether system. The vehicle requirements and operational criteria would provide additional protection to the public by mitigating potential hazards posed by a tether system failure.
The proposed rule would alleviate burdens on both the vehicle operator and the FAA. The operator would no longer incur the costs associated with submitting a launch license application, permit application or petition for waiver under chapter III. In addition, the operator would not incur the costs associated with any delay in processing applications or waivers. Finally, the FAA would not have to evaluate applications, conduct independent analyses, or issue licenses, permits or waivers.
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Discussion of the Proposal
This proposal would amend two sections of part 400. It would revise Sec. 401.5 (Definitions) to add a definition for a tether system. It would also revise Sec. 400.2 (Scope) to add requirements for the launch vehicle and tether system, as well as separation distances from the public for the tethered launch operations.
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Proposed Definition (Sec. 401.5)
The FAA proposes to define tether system as a device that would contain launch vehicle hazards by physically constraining a launch vehicle in flight to a specified range from its launch point. A tether system includes all components, from the point of attachment to the vehicle to a solid base, that experience load during a tethered launch.
A tether system should prevent a vehicle from departing the launch site because the vehicle could pose a hazard to the public. Typically, a tether system is composed of at least three parts: one vehicle connection; one fixed connection; and at least one tether that has one end fastened to the vehicle connection and the other end fastened to a fixed connection to a solid base so as to limit the vehicle's range of movement. A vehicle connection consists of all mechanical components that attach a tether to a launch vehicle. These include, for example, metal frames, bolts that attach the vehicle and metal frame together, and shackles. A fixed connection attaches a tether to a solid base, such as a crane, a forklift or
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the ground, and it consists of all mechanical components that accomplish the attachment. Examples of these mechanical components include the component that attaches any crane to the rest of the system, such as shackles or a bolt that attaches a solid base and shackle together.
The FAA's proposed definition is broad enough to encompass all possible tether system configurations. This proposed definition would require operators, when determining if chapter III applies, to account for the effect of a tethered launch on every component from the point of attachment to the vehicle to a solid base, that experience load during a tethered launch. Accounting for a whole system would reduce the likelihood of a system failure caused by an overlooked component that was unable to withstand the maximum load exerted on it.
In devising a tether system, the operator should take into account the vehicle's structural integrity because if the tether were able to withstand the forces exerted on it, but the vehicle could not, then the vehicle could break free. If this were to happen and the vehicle exceeded the proposed flight limit of 75 feet above ground level (AGL), the operator would have failed to comply with the proposed requirement in Sec. 400.2(c)(2)(iii).
The FAA's proposed definition accounts for only one tether, regardless of any other tethers within the system. A tether system containing multiple tethers or multiple attachment points is not necessarily more reinforced or safer: all of the applied forces may not be evenly distributed among the tethers. For instance, for a tether system with four tethers, if an operator assumes that the maximum load is evenly distributed among all four tethers of the system and designs each tether to withstand one-fourth of the maximum load, the entire tether system could fail if the vehicle's position shifted and more than one-fourth of the maximum load was placed on a single tether. In other words, if one tether can fail, then all tethers within the system can fail. Accordingly, in order to reduce the likelihood of a tether system failure, the system must contain at least one tether capable of bearing the maximum force exerted on the tether system, regardless of the number of additional tethers within the system. Increasing the number of tethers within the system does not guarantee an increase in strength for the overall system.
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Proposed Launch Vehicle (Sec. 400.2 (c)(1))
In order to avoid the applicability of chapter III, the FAA proposes that a launch vehicle would have to be unmanned and meet the requirements proposed below.
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Engine Type
The FAA would require a launch vehicle excluded by tether from chapter III to have a liquid or hybrid motor; a solid rocket motor would not be permitted. Liquid or hybrid motors are composed of systems that require mixing of the propellants to combust, whereas solid motors consist of relatively simple systems where the propellants are already formulated with oxidizer dispersed in fuel. If a tethered vehicle were to lose control, the operator would rely on the tether system to constrain the vehicle and bring it to the ground. The fragile nature of liquid or hybrid motors ensures that ground impact would render them inoperable.
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Propellant Cap
The FAA would not permit a launch vehicle to carry more than 5,000 pounds of propellant. The FAA's records indicate that, historically, the most propellant that has been on board a launch vehicle for a tethered launch is approximately 1,000 pounds. Greater propellant amounts result in both a heavier launch vehicle and greater explosive energy.
To determine this proposed cap, the FAA assessed the weight capacity of cranes and forklifts from a random sampling and from data used during past tethered launches. The data from the past launches indicate that the average weight capacity of these crane or forklift tether systems was 6,000 pounds; however, there were gaps in the data because this information was voluntary and not all operators provided it. To fill in the gaps, the FAA randomly selected eleven crane and forklift models from several manufacturers.\2\ The data obtained from the random samples indicate that the average weight capacity of a crane or forklift is also approximately 6,000 pounds. For a tethered vehicle, the vehicle's dry weight uses a maximum of approximately 15 percent of the crane or forklift weight capacity.\3\ This leaves approximately 85 percent of the weight capacity available for the propellant. To compute the maximum propellant amount that a tethered vehicle can carry, the FAA took the 6,000-pound crane or forklift weight capacity and multiplied it by 85 percent. This computation resulted in a maximum propellant weight of 5,100 pounds. To provide a margin for the weight capacity of the crane or forklift, the FAA rounded this value down to 5,000 pounds.
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\2\ Models from the random sampling consisted of the Broderson IC20, Broderson IC35, Case 586G, JCB 930, John Deere 486E, Genie GTH5519, Genie GTH636, Genie GTH644, Gradall G6-42Z, Gradall G6-42P, Lull 644E-42.
\3\ Some operators provided voluntary information on their tether systems. The FAA looked at the different vehicles' dry weights relative to the crane or forklift weight capacity.
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Proposed Tether System (Sec. 400.2(c)(2))
The FAA proposes conservative technical and design criteria for an effective tether system. The FAA developed these criteria by determining what would prevent a tether from breaking and exposing the public to launch vehicle hazards. The FAA proposes five criteria as necessary to reduce the risk of a tether system failure: (1) Established strength properties, (2) minimum factor of safety, (3) launch vehicle constraint, (4) no damage displayed before launch, and (5) protection from launch vehicle exhaust plume.
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Established Strength Properties
The FAA would require that an eligible tether system have established strength properties that would not yield or fail under the maximum dynamic load on the system or under a load equivalent to two times the maximum potential engine thrust.
Because some operators may not readily know the maximum dynamic load for their tether systems, the FAA proposes an alternate means of determining whether the tether is of sufficient strength. If an operator does not know the maximum dynamic load, the operator may calculate the maximum load as follows: determine the maximum potential engine thrust of the tethered vehicle and then multiply the maximum engine thrust by a factor of two. Using the maximum potential engine thrust of two is an industry standard for estimating the dynamic load of any structural system.\4\
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\4\ See A.E.H. Love, A Treatise on the Mathematical Theory of Elasticity, 179-180, Cambridge University Press (2d ed. 1906).
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Minimum Factor of Safety
The FAA would require operators to multiply the maximum load by a minimum factor of safety \5\ of 3.0 for
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yield stress and 5.0 for ultimate stress. All components would have to have established strength properties that could withstand the maximum load multiplied by the factors of safety. The FAA chose the proposed factors of safety based on their successful history in a similar context.
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\5\ A factor of safety of 1.0 implies that the design meets minimum requirements, but is on the point of failure with design uncertainties and no margin for variation or error. A factor of safety less than 1.0 means the design does not meet the minimum requirements and is in a failed state. A factor of safety greater than 1.0 means the design exceeds the requirements by a multiple of that factor of safety and is in a safety state.
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The U.S. Air Force has used these same factors for similar operations. The U.S. Air Force conducts rocket operations at the Eastern and Western Ranges, including of tethered and ground-based systems. It recommends a minimum factor of safety of 3.0 for yield stress,\6\ and a factor of safety of 5.0 for ultimate stress,\7\ for the design of ground-based systems. This includes the tether and its attachments to launch facilities or ground equipment.\8\ This means that for a tether system, the components within the system would be able to endure three times the force required to permanently deform the components, and five times the force required to break the components. The U.S. Air Force has not experienced any tether failures, even for a Minuteman launch, using these factors.
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\6\ Yield stress is the elastic limit.
\7\ Ultimate stress is when breakage occurs.
\8\ Nicholas E. Martino, Design and Analysis Guidelines for Launch Vehicle Tether Systems, Aerospace Report No. ATR-2008 (5377)-
1, The Aerospace Corporation (Sept. 30, 2007). This report is available in the docket for this rulemaking (Docket No. FAA-2012-
0045).
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Launch Vehicle Constraint
The FAA proposes that the launch vehicle be constrained so that its flight cannot exceed 75 feet AGL. This altitude limit is based on the FAA's assessment of historical data on tether lengths and on the height of cranes and forklifts to determine a safe maximum altitude for tether systems. Based on this assessment, the FAA calculated an average crane or forklift height and an average tether length. The FAA then added these two values together to determine the launch vehicle's potential altitude.
Crane and forklift data from previous tethered launches and sampling indicate that the average height of the crane or forklift in a tether system is 43 feet. There were gaps in the data because the information was voluntary, and not all operators provided it. To fill the gaps, the FAA examined random samples of different crane and forklift heights, which indicated that operators typically use mid-
sized cranes and forklifts to conduct their tethered operations. The FAA then took samples of mid-sized cranes and forklifts and averaged their heights and weight capacities to determine their physical limitations. The FAA obtained the samples from online brochures of manufacturers of cranes and forklifts.\9\ The sample information also indicates that the average crane or forklift height is approximately 43 feet.
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\9\ These included Broderson Manufacturing Corp.; JCB; Genie; and Gradall Industries, Inc.
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A launch vehicle's potential altitude is a crucial element in determining how far debris can travel in the event of a crash or an explosion. Large tether lengths allow for high altitude flights, while short tether lengths limit the vehicle to low altitudes. This means that a tether system failure during flight can result in large vehicle ranges for long tethers and short vehicle ranges for short tethers, because altitude and range are proportional. In order to reduce the risk to the public during tethered launches, the tether length must not be too long. An appropriate length is also necessary to prevent hazardous events, such as the entanglement of the tether with launch support structures or other facilities. Moreover, an appropriate tether length would prevent a controlled airspace incursion.
The FAA assumed that the maximum tether length for the average crane or forklift tether system would not be greater than the crane or forklift height because such a tether length could allow a launch vehicle to hit the ground and possibly explode. The FAA also assumed that the tether must be given room to stretch, because a 43-foot tether attached to a 43-foot high crane could allow the launch vehicle to hit the ground when the length of the vehicle and the elasticity of the tether are taken into account. Based on these assumptions, the FAA concluded that the tether length should be less than 43 feet.
The FAA examined past tether waiver applications to determine the appropriate tether length. The tether waiver data showed that the maximum tether length operators typically use is approximately 32 feet. The FAA would use a tether length of 32 feet, which provides a margin of 11 feet to account for the tether's elasticity and the length of the vehicle, to calculate maximum altitude. This length is appropriate and reasonable for tethered flights because past tethered flights have demonstrated that the length allows the vehicle sufficient lateral movement for operators to conduct tethered activities, while limiting the vehicle to low altitudes and thereby reducing the risk to the public.
When the average crane or forklift height of 43 feet is added to an appropriate tether length of 32 feet, the result is a maximum potential altitude of approximately 75 feet for the tethered vehicle. Accordingly, the FAA proposes to require that the tether system physically constrain the launch vehicle within an altitude of 75 feet AGL. This altitude does not require operators to use 43-foot high cranes or 32-foot long tethers; those measurements were only used to calculate an appropriate maximum altitude for a tethered launch that would not require FAA oversight. The proposed maximum altitude would protect the public by limiting the launch vehicle's range.
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No Damage Displayed Before Launch (Sec. 400.2(c)(3))
The FAA would require that the tether system show no visual component damage before each launch. This requirement would reduce the risk of a tether system failure due to pre-existing damage. A visual check of the tether system before each launch could prevent failure by identifying signs of damage such as component fatigue, fracture, wear, creep, corrosion, yielding, or thermal shock. While the initial stages of some of these forms of damage may not be visible to the naked eye, they may eventually become visible. The FAA offers the following definitions of these terms as guidance in conducting the visual check:
ssquf Fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. Fatigue occurs when a material is stressed repeatedly.
ssquf Fracture is the local separation of an object or material into two or more pieces under the action of stress.
ssquf Wear is the erosion of material from a solid surface by the action of another surface. Wear is related to surface interactions and more specifically to the removal of material from a surface as a result of mechanical action.
ssquf Creep is the tendency of a solid material to move slowly or deform permanently under the influence of stresses.
ssquf Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings.
ssquf Yielding is when a material begins to deform plastically; when the yield point is passed, some fraction of the deformation will be permanent and non-reversible.
ssquf Thermal shock is cracking as a result of rapid temperature change.
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Protection From Launch Vehicle Exhaust Plume
The FAA would require an operator to insulate or locate the tether system such that it will not experience thermal damage due to a launch vehicle's exhaust. This requirement would mitigate the risk of a tether system failure due to thermal damage. Components exposed to the heat emitted from a launch vehicle's exhaust plume may be damaged or severely weakened. Metallic components, for example, that are exposed to a vehicle's exhaust plume may not visually show damage; however, all structural materials suffer significant strength degradation at elevated temperatures.
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Proposed Separation Distances (Sec. 400.2(c)(3))
The FAA proposes that tethered launches be conducted at a sufficient distance from the public and from property belonging to members of the public to mitigate the effects when a launch vehicle unintentionally separates from the tether system. A launch vehicle may transfer unanticipated loads into the tether system, resulting in tether system failure and vehicle separation. Although a properly designed and constructed tether system should not fail, adding distance between the launch point and members of the public is a prudent and relatively simple and inexpensive safety measure to implement.
The FAA computed its proposed separation distances by first calculating a conservative maximum range of a vehicle that broke free of the tether system, and then calculating the hazardous fragment distance from the point of impact based on the type and amount of propellants onboard. Table A--Separation Distances for Tethered Launches in proposed Sec. 400.2 would contain the separation distances required for a tethered launch that was excluded from chapter III. Each distance calculation in Table A is discussed below.
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The Maximum Range of the Vehicle Released From the Tether
To determine a launch vehicle's maximum range, the FAA used Newton's equations of motion to estimate the maximum possible distance a vehicle that broke free of a tether could travel. The FAA simulated the scenarios where a tether system failed, and the vehicle followed a ballistic trajectory to the ground. The analysis consisted of the following assumptions: (1) The vehicle would be non-propulsive upon release; (2) the initial release velocity of the vehicle was maximized; (3) the tether's pull would not reduce the vehicle's velocity; (4) the tether would fully extend upon release; (5) the release angle of the vehicle would be the angle that provided the maximum range; and (6) the vehicle would fly through a vacuum. Except for the non-propulsive nature of the vehicle, all assumptions are conservative from a public safety perspective. The non-propulsive assumption is reasonable because a vehicle that broke free of a tether would most likely be unstable and not able to sustain flight in any particular direction.
The FAA also conducted a computer simulation of the same scenarios, using a trajectory analysis tool to verify the validity of the FAA's maximum range calculations. The numerical results from the computer simulation were consistent with the results from the FAA's computational analysis.
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The Hazardous Fragment Distance Based on the Propellant Onboard
Upon impact at its maximum range, a launch vehicle with liquid propellants has the potential to explode, creating both overpressure and debris hazards. Explosive hazards associated with propellant quantities up to 5,000 pounds are driven by fragment hazards. The FAA used the formulas provided in Table 1 below to determine the hazardous fragment distance given a launch vehicle impact. This distance is a function of the net explosive weight (NEW), or the explosive equivalent of the propellants used on the launch vehicle.\10\ Depending on the type of propellant, the explosive equivalent may vary from 10 to 20 percent, in accordance with Table E-2 of part 420.\11\ For purposes of this rulemaking, the FAA applied a maximum NEW value of 20 percent for all propellant types. Using this conservative assumption simplifies the proposed rule.
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\10\ The definitions of NEW and explosive equivalent weight are provided in 14 CFR 420.5.
\11\ Explosive Siting Requirements, Notice of Proposed Rulemaking, 76 FR 8923 (Feb. 16, 2011).
Table 1--Hazardous Fragment Distance \12\
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Hazardous fragment distance
Net Explosive Weight (NEW) (d), feet
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