Engineering Safety Factors

(Slightly Revised April 2024)

Project

Safety Factor

Reference

Unmanned Solid Rocket Motors (Minuteman)

1.1

[1]

Manned Solid Rocket Motors (Skybolt/Genie)

1.25

[1]

General Dynamics “Atlas Team” Safety Factor

1.25

[2]

Von Braun “Rocket Team” Safety Factor

1.35

[2]

References:

[1] Project Apollo, A Feasibility Study of an Advanced Manned Spacecraft and System: Final Report, Volume IV On-Board Propulsion, Book 2 – Appendix P-A, General Electric (15 May 1961)

“Chamber Wall thicknesses of solid motors are based on the determined yield pressure times the maximum expected operation pressure (MEOP) encountered during motor operation.

Solid motors used on manned systems such as Skybolt/Genie, have a Factor of 1.25 MEOP.

Solids used on unmanned systems such as Minuteman have a factor of 1.1 MEOP.”

[2] NASA-SP-2004-4230 Taming liquid hydrogen : the Centaur upper stage rocket, 1958-2002

“Asked at the hearing about the difference in design philosophy between General Dynamics and Huntsville, Hansen agreed that Huntsville’s was more conservative. In contrast to the 35-percent margin of safety the von Braun team specified in its contracts, the contract between General Dynamics and the Air Force [for Atlas] allowed a 25-percent margin.”