DEPARTMENT OF THE AIR FORCE SMC REGULATION 80033
Headquarters Space and Missile Systems Center (AFMC)
Los Angeles Air Force Base, California 900092960
Performance Margins For Launch Vehicles
1. Policy: The following policy is applicable to all space launch vehicle programs including (a) multistage launch vehicles, (b) singlestage launch vehicles, and (c) upper stages. The policy provides standardization and control of performance margin for space launch vehicles during design, modification and operational phases.
2. Background: To minimize the risk of failure to deliver a payload to its required orbit within specified tolerances, a statistically determined performance margin needs to be reserved and controlled during design, modification and operational phases of space launch vehicles (LV). The performance margin analysis evaluates anticipated parametric dispersions and determines the nominal and 3-sigma propellant (or velocity) margin requirements. The LV contractor shall demonstrate that the LV has sufficient propellant to protect for the 3-sigma parametric variations.
While there is no single standard approach to perform this margin analysis, one of various known analytical approaches may be used by the LV contractor, and shall be subject to the approval of the SPO.
Performance margin usable performance capability reserved to protect mission injection conditions. Typically expressed in terms of propellant margin or velocity margin.
Margin contingency performance margin reserved for uncertainties in nominal vehicle parameters or their dispersions. Used to protect vehicle capability requirements for modifications or new design.
TAG Tested And Guaranteed parameters. Measured parameters and associated dispersions for specific hardware and/or software used on a specific launch vehicle.
Class generic parameters. Parameters and associated dispersions that include the hardware and/or software characteristics of all launch vehicles of a given configuration.
Analytical (bottomsup) performance margin requirement vehicle performance margin requirement determined using system dispersions. The system dispersions shall be consistent with the prediction methods used and based on implementation of appropriate TAG or class data. Examples of dispersions to be included are: (1) propulsion systems, (2) propellant utilization, (3) propellant weights, (4) mass properties, (5) aerodynamics, (6) environments, (7) guidance, navigation, control.
Track record (topsdown) performance margin requirement compilation of actual performance margin consumption determined for each flight, normalized to a consistent baseline, and calculated relative to analytical (bottomsup) margin. Statistical data from all applicable vehicles forms the topsdown margin track record requirement. The topsdown track record shall be periodically updated.
4. Responsibilities and Procedures: Each SMC launch vehicle program office shall obtain a performance margin analysis from their contractor.
a. For a mature launch vehicle program, the contractor shall justify and implement an approved 3sigma performance margin to protect mission injection conditions for flight dispersions. The performance margin shall be greater than or equal to the track record 3sigma margin requirement. Additional margin can be reserved by the program for performance protection associated with concerns such as hardware anomalies and biases.
b. For modification to a mature launch vehicle program, the same performance margin requirement shall apply as for a mature launch vehicle program plus margin contingency for the modification. The contractor shall justify and implement an approved margin contingency and depletion schedule for the modification including all parameters contributing to performance margin. The parameters shall include, but not be limited to contingencies for propulsion system, propellant utilization system, propellant weight, dry weight/mass properties, and aerodynamics. Major events in the depletion schedule of margin contingency shall include, but not be limited to (a) contract award, (b) Preliminary Design Review (PDR), (c) Critical Design Review (CDR), (d) first test, (e) final test, (f) first flight, (g) flight at which contingency is removed.
c. For a new launch vehicle program, the contractor shall justify and implement an approved 3sigma margin to protect mission injection conditions for fight dispersions. The performance margin shall be greater than or equal to the analytical (bottomsup) 3-sigma margin requirement. Additional protection shall be allocated for topsdown track record impacts.
The contractor shall justify and implement an approved margin contingency and depletion schedule. The margin contingency at contract award shall be greater than or equal to the larger of (a) derived contingency including all parameters contributing to performance margin, or (b) an allocated payload capability contingency requirement consistent with programmatics. Major events in the depletion schedule of margin contingency shall include, but not be limited to (a) contract award, (b) Preliminary Design Review (PDR), (c) Critical Design Review (CDR), (d) first test, (e) final test, (f) first flight, (g) flight at which contingency is removed.
Additional margin reserve shall be considered by the program for engine out or other flight anomalies protection.
d. The payload user program shall have the option of reserving launch vehicle performance margin in the space vehicle. The space vehicle delta velocity (V) capability must be sufficient to (a) protect mission injection conditions for launch vehicle dispersions and other launch vehicle performance margin requirements, (b) satisfy launch availability requirement. The payload user requirements shall be documented in the space vehicle-to-launch vehicle Interface Control Document (ICD).
e. Demonstration of generic vehicle compliance with specification capability requirements shall use performance margin requirements consistent with the launch vehicle development status (as defined in the above paragraphs) plus margin reserved for vehicletovehicle capability differences. The contractor shall justify and implement an approved margin reserve for vehicletovehicle capability differences including all parameters contributing to performance margin.
5. Instructions for applying and executing this regulation are provided by SMC Regulation 540-15 (Systems Engineering Policy). Any program director who does not apply and execute this regulation, as required by SMCR 540-15, shall immediately request a waiver from the Commander.
EDWARD P. BARRY, JR.
Lieutenant General, USAF, Commander