NASA Office of Logic Design

NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

TABLE VIII

COMPARISON OF APOLLO AND SOYUZ PYROTECHNIC INITIATORS

CHARACTERISTIC

SOYUZ

 APOLLO
INITIATOR TYPES USE TWO TYPES OF INITATORS
  1. Dual bridgewire cartridges
  2. Pyrotechnic bolts
 USES STANDARD SINGLE BRIDGE-WIRE INITATOR FOR ALL FUNCTIONS (SBASI)
PYROTECHNIC MATERIALS UNKNOWN ZIRCONIUM AND POTASSIUM PERCHLORATE
DC SAFE POWER LEVEL
(NO-FIRE LEVEL)		 ~ 1.5 MILLIWATTS/50 MILLIAMPS ~ 1 WATT/1AMP FOR 5 MINUTES
DC FIRE LEVEL ~ 400 MILLIWATTS ~ 3.5 WATTS
RF FIRING LEVELS SAME AS FOR DC: PIN-TO-PIN MODE ONLY VARIES WITH FREQUENCY: PIN-TO-PIN AND PIN-TO-CASE MODES
CIRCUIT SHIELDING CONTINUOUS FROM FIRING RELAYS TO INITIATOR.  360º CONNECTION AT INITATOR BACKSHELL SHIELDING HAS DISCONTINUITIES AT BULKHEAD CONNECTORS.  360º CONNECTION AT INITIATOR BACKSHELL
TWISTED PAIR WIRING YES YES
CIRCUIT GROUNDING FLOATING FIRING CIRCUITS GROUNDED/SHORTED FIRING CIRCUITS WHEN SAFED

From "annual report to the nasa administrator by the aerospace safety advisory panel," part I - apollo soyuz test project, section 2 - summary of information developed in the panel's fact-finding activities.  february 1975.

soyuz_vs_apollo_pyros.jpg (119998 bytes)

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