We know that the stages of Saturn V were mounted to each other with explosive bolts. Separation was done by ignition of these pyrotechnics.

But we also know the control computer of the Saturn V was placed on top of the third stage and controlled the first and second stage too. So there were cables from third stage down to first stage.

To cut cables between Apollo CM and SM pyrotechnic guillotines were used. Also between first and second stage of the LM.

See this question and this.

So there should be also pyrotechnic guillotines within the stages of Saturn V.

Are there any reports about the pyrotechnic guillotines within Saturn V?

  • $\begingroup$ The most detailed documents I have - the "Flight Manuals" - just show linear shaped charges (LSC) in the separation systems. It may be that the cables were just severed by the LSCs. $\endgroup$ Feb 26 at 2:09
  • $\begingroup$ @OrganicMarble So cables may be cut by a guillotine or a LSC, but a LSC may damage other parts close to the LSC? A LSC in LM may damage the upper stage, but a LSC in the lower stage of the Saturn V is so far away from the upper stage that damages are impossible? $\endgroup$
    – Uwe
    Feb 26 at 11:07

There was no need for guillotines on the Saturn V. Signals between stages were passed through mated electrical connectors, which simply pulled apart during stage separation. There even were pins in the connectors to sense the continuity of the connection. (Sources for this answer are the Saturn V Flight Manual.)


In order for the Saturn V launch vehicle and Apollo spacecraft to accomplish their objectives, a continuous flow of data is necessary throughout the vehicle. Data flow is in both directions: from spacecraft to stages, and from stages to the spacecraft. The IU serves as a central data processor, and nearly all data flows through the IU.

Specific data has been categorized and tabulated to reflect, in figure 1-4, the type of data generated, its source and its flow. Each stage interface also includes a confidence loop, wired in series through interstage electrical connectors, which assures the Launch Vehicle Digital Computer (LVDC) in the IU that these connectors are mated satisfactorily.

p. 1-3

Each stage had its own batteries for power, and no fluids were passed between stages. Thus, explosive charges only needed to separate the structures of the stages; there was no need for guillotines.

The digital signals from the Launch Vehicle Digital Computer were routed to boxes on each stage, near its associated pyrotechnic, called "EBW (explosive bridgewire) firing units". These units generated electrical pulses with enough energy to detonate the explosive:

The storage capacitor in each of the EBW firing units is charged by 28 vdc power during the latter part of S-IC boost. The trigger signal causes the storage capacitor to discharge into an EBW detonator which explodes the bridgewire to release energy to detonate the explosive charge in the detonator.

p. 5-24


The EBW firing units are armed by charging their storage capacitors to 2300 volts about five seconds after the S-IVB ullage rockets have stopped firing. A trigger signal releases the high voltage pulse to explode the bridgewire in the EBW detonator. Either detonator will detonate both CDF assemblies (figure 6-26) through the detonator block.

p. 6-32

The ordnance systems on the Saturn V are as follows, in the order that they are ignited:

  • 8 retrorockets on the S-IC, ignited by a redundant pair of EBW firing units, to pull the first stage away from the rest of the rocket during separation.
  • A redundant pair of EBW firing units on the interstage ring, which detonate a linear-shaped charge to separate the S-IC first stage from the interstage ring.
  • 4 ullage rockets on the S-II second stage, ignited by a redundant pair of EBW firing units, to settle the propellants in their tanks and to help with the separation of the interstage ring.
  • Another redundant pair of EBW firing units on the interstage ring, which detonate a linear-shaped charge to separate the interstage ring from the S-II second stage. Note that this separation disconnects the signal that caused it (although it does not matter).
  • 4 retrorockets on the S-II, ignited by a redundant pair of EBW firing units, to pull the second stage away from the rest of the rocket during separation.
  • A redundant pair of EBW firing units on the interstage attached atop the second stage, which servers the tension straps between the S-II and S-IVB stages. This is another separation that disconnects the signal that causes it.
  • Two ullage rockets on the S-IVB third stage, ignited by a redundant pair of EBW units.
  • A redundant pair of EBW on the S-IVB to detonate four frangible nuts, to jettison the ullage motor assembly to save weight.

In addition, each stage has a redundant pair of self-destruct systems. These are controlled by a radio signal from the range safety officer, rather than the Launch Vehicle Digital Computer.

  • 2
    $\begingroup$ Guillotines were needed only to cut a tube for gases or liquids. For SM and LM, the guillotines needed for the tubes could be used for electric cabels too. The use of the guillotines for both the tubes and cabels helped to save weight of SM, LM and CM. No connectors in the module interface, only cabels. $\endgroup$
    – Uwe
    Jun 22 at 8:13
  • $\begingroup$ Any idea what the connectors looked like? $\endgroup$
    – gwally
    Jun 22 at 18:08
  • $\begingroup$ @gwally: Not specifically for the connectors between Saturn stages. However, there are lots of drawings showing wiring elsewhere in the Saturn; anything that isn't hardwired uses standard round MIL-type connectors. There is a drawing of the connection between the Saturn launch vehicle and Apollo payload; it uses round MIL connectors that simply pull apart. It's likely that the connections between stages did the same thing. $\endgroup$
    – DrSheldon
    Jun 22 at 22:34

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